DE102014224588A1 - Method for producing metallized ceramic substrates - Google Patents

Abstract

Disclosed is a method of manufacturing a metallized ceramic substrate in which the ceramic substrate and the metal layers are tilted during manufacture.

Description

The present invention relates to a method for producing a metallized ceramic substrate, to the metallized ceramic substrates obtainable by this method and to carriers used in the method according to the invention for producing the metallized ceramic substrates.

Metallized ceramic substrates are used in the field of power semiconductor modules. In this case, a ceramic substrate is provided on the upper side and possibly on the underside with a metallization, wherein usually at least one metallized side later has a circuit-technical structure, for example, produced by etching processes. The known method for producing such metallized ceramic substrates is by eutectic bonding and is commonly referred to as a direct-bonding process.

Basic descriptions of methods of making metallized ceramic substrates by bonding processes can be found in the references US 3,744,120 . US 3,994,430 . EP 0 085 914 A or the DE 23 19 854 A are taken from, the corresponding disclosure of which is incorporated by reference into the present invention. This known production method is common, for example in the context of the direct copper bonding process (DCB process), that a copper foil is first oxidized in such a way that a substantially uniform copper oxide layer results. The resulting copper foil is then positioned on a ceramic substrate and the ceramic substrate / copper foil composite is heated to a bonding temperature between about 1025-1083 ° C, thereby forming a metallized ceramic substrate. Finally, the resulting metallized ceramic substrate is cooled.

The bonding of the ceramic substrate and the metal foil is carried out in an oven, so-called bonding furnaces generally being used. Corresponding bonding ovens, often referred to as tunnel ovens include, inter alia, an elongated tunnel-like furnace chamber (also called muffle) and a transport device with a transport element, for example in the form of a flexible and heat-resistant conveyor belt for transporting the material to be treated by the heated furnace with a heater chamber. The ceramic substrates are positioned together with the metal foil on a carrier on the conveyor belt and then passed through in the bonding oven by the conveyor belt driven a heating area in which the required bonding temperature is reached. At the end of the bonding process, the resulting composite of ceramic substrate and metal foil is cooled again.

This method can be used in principle for the production of single-sidedly metallized ceramic substrates as well as for the production of double-sided metallized substrates. In this case, the production of double-sided metallized substrates usually takes place via a two-stage bonding process.

In this two-step bonding process for making double-sided metallized ceramic substrates, the ceramic is bonded in two furnace passes to the metal layers on opposite sides of the ceramic substrate. For this purpose, a ceramic substrate is first positioned on a support and then placed on the overhead, d. H. on the side facing away from the carrier, covered with a metal foil. By the action of heat, this side of the ceramic substrate is connected to the metal layer and subsequently the resulting assembly is cooled. Subsequently, the substrate is turned over and in a second bonding step, the other side of the substrate is provided in the same way with a metal layer. In the case of the coating of the second substrate side, the metal layer already formed on the ceramic substrate in the first bonding step would rest on the carrier, whereby due to the required bond heat for the second metallization, this already formed first metal layer may also be melted. This would result in misalignments in the initially formed metal layer on the ceramic substrate, since there are interactions between the partially melted first metal layer and the carrier on which the first formed metal layer is located with the substrate. Corresponding misalignments can result, for example, from residues of the carrier material or other foreign bodies which adhere to the molten metal layer after removal from the carrier. Moreover, when the one-sided bonding process is carried out, for example due to the bimetallic effect of the single-sidedly bonded substrate, during the heating in the bonding furnace, bending of the metallized substrates on one side may occur.

To reduce such impairments of the metallized substrate surfaces by interactions with the carrier material, for example, describes the DE 10 2004 056 879 A a method of making double sided metallized ceramic substrates using the direct bonding process wherein an array of at least two metal layers and a ceramic substrate disposed between the metal layers is positioned on a carrier provided with a release layer and then the device is heated to a temperature at which the two metal layers bond to the ceramic substrate , The use of a corresponding separating layer should not lead to a connection of the carrier to the adjacent metal layer of the arrangement.

Nevertheless, even with the use of such separating layers, at least one of the already metallized layers has a large area on a contact surface, and it is desirable to avoid such an additional contact surface with the metallized substrate sides as far as possible.

On the other hand, for example, describes the DE 10 2010 023 637 A a method for producing double-sided metallized substrates in a single method step, wherein a first metal layer, a substrate and a second metal layer are sequentially positioned in a given order on a support, wherein the carrier at the top, that of the arrangement of the first and second Metal plate and facing the substrate, having a plurality of projecting lugs, which taper in the direction of the arrangement of the first and second metal plate and the substrate. These projecting lugs are preferably distributed over the entire top of the carrier. According to the statement DE 10 2010 023 637 A Due to the structuring of the carrier with tips, it is achieved that the composite of metal plates and ceramic substrate can be detached from the carrier without residue after the two-sided bonding process. This is intended to prevent damage to the metal layer which rests on the carrier during the bonding process. Nevertheless, there are still numerous points of contact between the projecting lugs and the surface of the metal layer to be bonded, which still creates detrimental interactions between the metal surface and support and, in particular, when using supports based on nitridic ceramics, e.g. B. AlN it comes to a superficial oxidation and thus possibly to a compound with the metal foil to be bonded.

The WO 2014/049414 relates to a direct-bonding method wherein the substrates are positioned on a planar support having grooves or grooves passing over the support surface of the support. Similarly describes the US 2007/261778 a direct bonding process using a planar support, the bearing surface of which is formed by grooves or columnar support points. However, even with these methods, numerous contact points still remain between the metal layer to be bonded and the carrier, which is disadvantageous for the said reasons.

In order to avoid the aforementioned disadvantages of the known methods for producing double-sided metallized substrates, it has furthermore been proposed to use carriers in which the substrates are fixed on carriers in such a way that the ceramic surfaces have as little as possible direct contact with other surfaces , such as the carrier or conveyor belt comes. This is on the one hand relevant to avoid the aforementioned adverse interactions of an already metallized surface with the carrier, but also to avoid a possible contamination of the ceramic surface to be metallized in a second bonding step by contact with the carrier or the transport chain. This is done for example by the use of carriers in which the substrates to be bonded rest only on the edges on a support or are supported on narrow supports on the short sides of the substrates. Corresponding carriers - also called Bond boats - are in the 1a and 1b shown.

However, the double-sided metallized substrates produced with the aid of these so-called bond boats also have disadvantages. For example, when using bond boats according to 1a with sloping supports 2 to the problem that already twisted substrates 1 slip into a position of the lowest center of gravity and thus further amplifies the already resulting from the ceramic substrate or first process step torsion. Also, by supporting the substrates over the long edges, as in 1a shown in the bonding process due to the higher bending moment over the longer edge, the deflection of the substrates are reinforced in the longitudinal direction. This results in substrates that suffer undesirable losses in their flatness. Both undesirable strengthening of the torsion and undesirable enhancement of the deflection of the substrates to be bonded affect the flatness of the resulting metallized substrates.

At the in 1b illustrated embodiment of bond carriers, in which the substrate 1 on edges 3 rests, is again disadvantageous that the substrates on the bottom can come in contact with, for example, the transport chain on which they are supported by the furnace, which will also result in quality losses. Here, too, by supporting the substrates via the short edges, as in 1b shown in the bonding process due to the higher bending moment over the shorter edge, the deflection of the substrates are reinforced in the transverse direction, thereby resulting in an undesirable loss of flatness.

The WO 2004/032593 describes a carrier for Dünnstsubstrate, wherein the support member for the substrate to be placed is designed as a frame member, so that here also takes place a contact between the carrier and substrate only in the edge region of the circumference of the substrates. The substrate is placed rigidly on these marginally positioned frame members and these are designed so that a deflection of the substrate is substantially completely avoided. These are the thinnest substrates of the WO2004 / 032593 However, glass or polymer films with thicknesses of less than 0.3 mm, which are bendable due to their small thickness, but thereby do not have a self-supporting structure, whereby these bend in the processing process due to their own weight and can be easily damaged in the processing process. Also due to their tendency to self-oscillation such substrates are easily damaged. Therefore, according to the statement WO2004 / 032593 for the substrate carriers described therein, it is essential that the surfaces of the substrates to be processed are held rigidly in one plane by them, and that any deflections are substantially completely avoided. This is achieved by firmly fixing the thinnest substrates to the carrier elements by gluing, clamping or covering. Thus, however, the method described therein is not suitable for the ceramic substrates of the present invention, since a rigid fixing of the ceramic substrates according to the invention on such a planar support would suppress the material bending and / or torsion tendencies occurring in the bonding process, on the one hand may lead to damage of the material and on the other hand would counteract the inventively desired oriented orientation and torsional reduction by the material bending occurring in the bonding process.

Similarly describes the WO2011 / 104222 a multi-layered substrate holder wherein the substrates are held over a peripheral frame. This application is primarily directed to glass substrates for the production of solar modules. Here, too, it is provided that the surfaces of the substrates to be processed are held in one plane and a possible bending or buckling of the substrates under the action of high process temperatures is intended according to US Pat WO2011 / 104222 be counteracted by cross struts with additional support points for the substrate surfaces. However, such cross struts with additional contact points for the substrate surfaces would, when used in the method according to the invention, again bring about additional points of contact between the metal layer to be bonded and the carrier, which should be avoided for the abovementioned reasons. Also, in the context of the present invention, a curvature or bending of the substrates occurring in the bonding process should not be counteracted mechanically for the reasons stated above.

Furthermore, the methods described above have the already mentioned problem of reinforcing a tendency to torsion already existing in the substrate.

In addition to these problems of unwanted deflection and possible reinforcement of an existing torsion, the hitherto insufficient positioning accuracy of the metal layer and the ceramic substrate relative to one another, in particular in the second bonding step of a two-stage bonding method, is disadvantageous in the above-mentioned prior art methods. Industrial fabrication of single-sided or double-sided metallized ceramic substrates according to the above-mentioned prior art methods does not involve a step of aligning the metal layers and the substrate with each other. If, for example, the metal layers are not positioned exactly flush on the substrate, arrangements of the respective methods result, for example, in which the metal layers extend beyond the edge of the ceramic substrate. These excess metal residues, which lead to further problems in the downstream process steps, then have to be removed, for example, by etching again and can also lead to an unnecessary material waste. If, for example, the metal layers extend beyond two edges of the ceramic substrate, such imprecise metallized ceramic substrates can usually no longer be processed further, so that this leads to a reduction in the production yield.

The variations in the specifications of the resulting metallized ceramic substrates resulting from these problems of the prior art, in particular impairment of the metallized layers by contact surfaces with the carrier, undesired torsion, insufficient flatness and inaccurate positioning of the metallizations, can be considerable in the subsequent processes as well as the processing negative effects and should therefore preferably be avoided.

On the basis of this prior art, the present invention thus first of all sets itself the general task of remedying the disadvantages of the prior art discussed above.

In particular, the present invention has the object to provide an improved method for producing single-sided metallized ceramic substrates, with which two-sided metallized ceramic substrates can be obtained by a two-step procedure.

Furthermore, the present invention has the object to provide a method for producing single-sided metallized ceramic substrates, with which two-sided metallized ceramic substrates can be obtained by a two-stage procedure and in which preferably the position accuracy of metal layer to ceramic is improved.

Furthermore, the present invention has the object to provide a method for producing single-sided metallized ceramic substrates, with which two-sided metallized ceramic substrates can be obtained by a two-step procedure and in which the resulting metallized ceramic substrates improved flatness, especially in thin ceramic substrates having a thickness ≤ 0.4 mm, and having a reduced torsion, which plays a role in particular in a subsequent system soldering or when using in a bottomless module.

method

• (1) Positionieren von einer Anordnung, umfassend zumindest eine erste Metallschicht und ein Keramik-Substrat, auf einem Träger;
• (2) Erhitzen der aus dem Verfahrensschritt (1) resultierenden Anordnung auf eine Temperatur, so dass es zu einem Verbund aus dem Keramik-Substrat und der anliegenden zumindest einen Metallschicht durch Bonden unter Ausbildung eines metallisierten Keramik-Substrats kommt.

These objects are achieved by a method for producing a metallized ceramic substrate, comprising the following method steps:

• (1) positioning an assembly comprising at least a first metal layer and a ceramic substrate on a support;
• (2) heating the assembly resulting from the process step (1) to a temperature such that bonding of the ceramic substrate and the adjacent at least one metal layer occurs by bonding to form a metallized ceramic substrate.

• – der Träger in Verfahrensschritt (1) an mindestens einer seiner randseitigen Kanten mindestens eine Auflage aufweist, auf der die Anordnung aus Verfahrensschritt (1) in mindestens einem randseitigen Teilbereich der Anordnung mit mindestens einer ihrer Außenkanten aufliegt, und
• – die mindestens eine Auflage auf dem Träger so angeordnet ist, dass die Anordnung beim Positionieren auf der Auflage des Trägers geneigt ist und/oder
• – der Träger mit der mindestens einen Auflage in Verfahrensschritt (1) nach dem Positionieren der Anordnung auf der mindestens einen Auflage des Trägers und/oder während des Verfahrensschritts (2) geneigt wird,
• – und worin der Träger an mindestens einer seiner randseitigen Kanten mindestens eine Begrenzung in der Form von mindestens einem Anschlag oder mindestens einer Kante aufweist.

The inventive method is then characterized in that

• - The carrier in step (1) on at least one edge edges thereof has at least one support on which rests the arrangement of step (1) in at least one edge portion of the arrangement with at least one of its outer edges, and
• - The at least one support on the support is arranged so that the arrangement is inclined during positioning on the support of the wearer and / or
• - the carrier with the at least one support in process step (1) is tilted after the positioning of the arrangement on the at least one support of the support and / or during the process step (2),
• - And wherein the carrier has on at least one of its edge edges at least one boundary in the form of at least one stop or at least one edge.

The inclination of the carrier can be achieved by a pivoting movement up to a zero slope or there is also a tendency to a negative angle in question.

In the context of the present invention, metal layers are, for example, metal foils or metal sheets made of copper, of a copper alloy or of a copper-containing alloy or of aluminum, of an aluminum alloy or of an aluminum-containing alloy.

"Ceramic substrates" in the context of the present invention are made of a ceramic material, preferably plate-shaped elements, which are provided on two of their surface sides with a metallization or are.

In the context of the present invention, an arrangement is understood as meaning a composite of at least one metal layer which is provided on a ceramic substrate, wherein the arrangement may be present before, during or after the bonding. In the context of the present invention, the arrangement is preferably substantially rectangular, including a substantially square arrangement. In this case, a substantially rectangular arrangement has two opposite substantially equal long longitudinal edges (long edges) and two mutually opposite substantially equally long transverse edges (short edges). A square arrangement has four edges of substantially equal length.

The term "essentially" in the context of the invention means deviations from the respective exact value by +/- 10%, preferably by +/- 5% and / or deviations in the form of changes insignificant for the function.

Further developments, advantages and applications of the invention will become apparent from the following description of exemplary embodiments and from the figures. In this case, all described and / or illustrated features alone or in any combination are fundamentally the subject of the invention, regardless of their summary in the claims or their dependency. Also, the content of the claims is made an integral part of the description.

The inventive method provides that the arrangement comprising the at least one metal layer and the ceramic substrate, in at least one peripheral portion of the arrangement with at least one of its outer edges on at least one support, which is arranged on at least one of the edge edges of the carrier , rests, and the arrangement comprising the at least one metal layer and the ceramic substrate, before or during the actual bonding in step (2) is inclined.

This inclination of the arrangement can be achieved by positioning the support with the at least one support arranged thereon on which the arrangement comprising the at least one metal layer and the ceramic substrate is either mechanically inclined after the positioning of the arrangement or at the time in which the arrangement comprising the at least one metal layer and the ceramic substrate on which at least one support of the carrier is positioned is already inclined.

The inclination of the arrangement can also be effected by positioning the at least one support or one or more of the supports arranged on the support itself, on which the arrangement comprising the at least one metal layer and the ceramic substrate is positioned, after positioning Arrangement is either mechanically inclined or at the time at which the arrangement comprising the at least one metal layer and the ceramic substrate is positioned on the at least one support of the carrier is already inclined.

In addition, it is possible that the inclination of the arrangement is effected in that both the carrier and at least one of the supports arranged thereon is correspondingly inclined or already inclined after the positioning of the arrangement.

In principle, therefore, the inclination of the arrangement, comprising the at least one metal layer and the ceramic substrate, can be effected by inclining the entire carrier, comprising the at least one support, and / or by the inclination of the at least one support.

Should it be provided that the carrier with the at least one support arranged thereon and / or the at least one support or one or more supports arranged on the support itself is tilted after the positioning of the arrangement, tilting can be carried out both in method step (1 ) and / or optionally in process step (4), d. H. in each case before the heating of the arrangement, or in process step (2) and / or optionally in process step (5), d. H. each time during the heating of the arrangement, take place.

Due to the inclination of the arrangement on the carrier, there is a defined orientation of the at least one metal layer and the ceramic substrate with each other: The at least one metal layer and the ceramic substrate slip through the inclination of the carrier itself or by the inclination, on the on the carrier is suitably arranged at least one support is effected, in a predetermined position, so that their arrangement is considered to each other as defined.

In addition, a fixation of the at least one metal layer and the ceramic substrate is achieved by the inclination of the carrier or at least one support such that slipping in the subsequent process steps is avoided.

In addition, with the method according to the invention on one side, as well as in a two-step procedure also double-sided metallized ceramic substrates produced in their entirety have a defined and constant orientation of the two metal layers and the ceramic substrate to each other.

In the production of only one-side metallized ceramic substrates, the above-described bonding process with the method steps (1) and (2) is carried out only once. This is in the Process step (1) the arrangement, comprising at least a first metal layer and a ceramic substrate, positioned on the support according to the invention that the ceramic substrate rests on the mounted on the support at least one support and the at least one metal layer on the support of Support side facing away from the ceramic substrate is applied. The thus positioned arrangement is then bonded in step (2).

• (3) Drehen des metallisierten Keramik-Substrats aus Verfahrensschritt (2) um eine parallel zu seiner Längs- oder Querkante verlaufende Drehachse;
• (4) Positionieren der Anordnung aus Verfahrensschritt (3) und zumindest einer weiteren Metallschicht, auf einem Träger, wie vorstehend definiert;
• (5) Erhitzen der aus dem Verfahrensschritt (4) resultierenden Anordnung wie in vorstehend beschriebenem Verfahrensschritt (2) definiert

durchgeführt.The production of double-sided metallized ceramic substrates is possible in a two-stage bonding process, wherein first a one-sided metallized ceramic substrate according to the above-described process steps (1) and (2) is produced. Subsequently, the additional process steps, comprising

• (3) rotating the metallized ceramic substrate from step (2) about a rotational axis parallel to its longitudinal or transverse edge;
• (4) positioning the assembly of step (3) and at least one further metal layer on a support as defined above;
• (5) heating the assembly resulting from the process step (4) as defined in the above-described process step (2)

carried out.

In this case, subsequent to method step (2), the ceramic substrate metallized on the side of the ceramic substrate facing away from the carrier is rotated such that a further metal layer is applied in the same way on the previously unmetallized ceramic substrate side in a next method step can. In this case, the first metallized side of the ceramic substrate is located on the side facing the carrier. Usually, the turning of the metallized ceramic substrate from method step (2) takes place by rotating about an axis of rotation parallel to the longest edge (longitudinal edge) or shortest edge (transverse edge) of the one-sided metallized substrate, corresponding to tilting about the longitudinal or transverse edge.

In addition to the method steps (1) to (5), in principle further method steps can be carried out. For example, the positioning in method step (1) and / or optionally in method step (4) can be carried out by mechanical alignment of ceramic substrate and metal layer manually or by means of a suitable alignment device. It is also possible, if necessary, for the one-sidedly metallized ceramic substrates resulting from process step (2) to be additionally aligned by suitable measures and, for example, to reduce bending of the metallised substrates on one side by suitable steps in the first bonding step becomes.

In the second bonding step according to method steps (4) and (5), in embodiments in which the ceramic substrate was not metallized symmetrically on the surface, using the identical carrier as in method steps (1) and (2), the already one-sided metallized substrate be struck in the second step on the opposite longitudinal edge. As a result, in the second bonding step, the alignment of the metal layer on the ceramic substrate which has already been metallized on one side would take place asymmetrically with respect to the opposite metal layer during positioning on the inclined support. In order to prevent this, different carriers are usually used in the first and second bonding step. The use of a second different carrier makes it possible, in particular, to strike the same edges in the first and in the second bonding step and thus to define the positioning of the second metal layer with the first metal layer on the ceramic substrate as accurately as possible.

Preferably, in the second bonding step after method step (4) and (5), a carrier is used which corresponds in construction to the carrier of the first bonding step from method steps (1) and (2) and is mirrored with respect to same by the same edge, on the one side metallized substrate from step (2) was rotated.

A rotation of the one-sided metallized substrate about the longitudinal edge (long edge) is preferably carried out when using carriers according to the invention, in which the supports are attached to the long edges of the carrier.

A rotation of the one-sidedly metallized substrate about the transverse edge (short edge) is preferably carried out when using carriers according to the invention, in which the supports are attached to the short edges of the carrier.

The use of an identical carrier in process step (1) and in process step (4) is possible if the dimensions of the metal layers and the ceramic substrate are coordinated so that the metal layer during the bonding process in step (2) and (5) respectively extends to the opposite ceramic edge and connects completely with the ceramic, so on the top and bottom symmetrically metallized ceramic substrates result.

In addition, an embodiment of a two-stage bonding method is possible in which the metal layer and the ceramic substrate are dimensioned or the position and size of the usable area on the substrate are designed so that the striking of the metallized substrate to the support in Method step (4) after rotating according to method step (3) for the resulting two-sided metallized product has no negative effects, for example in the form of damage to the metal layer in the edge region of the metallized substrate has. For example, embodiments are conceivable in which a metallization is provided, which leaves a protruding ceramic region in the edge region in which the arrangements rest on the at least one support of the support. In such cases, it is also conceivable to use a carrier with identical configuration in the first and second bonding step.

In the context of the present invention, it is particularly preferred that the arrangement according to the invention, both the arrangement of method step (1) and, if appropriate, the arrangement of method step (4), in each case rests exclusively in at least one peripheral portion of the arrangement with at least one of its outer edges. This means that, according to the invention, it is particularly preferred that the arrangements according to the invention, except in the outer edge region, have no further contact with the support or with supports and / or stops attached thereto. According to the invention, this exclusive edge-side subarea of the arrangements according to the invention designates the region of the circumference in which the arrangements according to the invention rest on the supports according to the invention during the bonding process. As a result of the subsequently defined size of the supports according to the invention, the size of this edge-side portion of the arrangements according to the invention accordingly results.

The ceramic substrates used in the method according to the invention can, before the actual bonding process is carried out in process step (2) and, if appropriate, before carrying out the second bonding process in process step (4), have per se a torsion as well as a certain intrinsic bending. In general, the ceramic substrates used in the process according to the invention are not completely flat. An existing self-bending and / or torsion of the substrate may change, ie amplify and / or reduce, during the subsequent bonding process in method step (2), and optionally in method step (5), under the action of corresponding bonding temperatures. In particular, a formation or reinforcement of such a bend due to the so-called bimetallic effect of the metallized substrates should be mentioned. The degree of flexure may also be effected by the inherent weight of the ceramic-metal composite in some combinations of materials and may be selectively affected by appropriate selection of the lateral support pads which reduce sagging of the ceramic substrate assembly and the at least one metal layer.

By means of the method according to the invention, in which the arrangement, comprising at least one first metal layer and one ceramic substrate, is positioned on one or more supports arranged on the carrier, the arrangement only has at least one edge-side partial area only with at least one of its outer edges rests on the support of the carrier, on the one hand, a reduction of a possibly existing torsion is achieved. In addition, the bending of the metallized ceramic substrates can also be influenced in a targeted manner by taking into account the material properties and a suitable choice of supporting supports

In the presence of a bent or twisted ceramic substrate, which rests only on a few points on the supports according to the invention while the other supports are not touched by the twisted or bent ceramic substrate due to the bending or torsion, heating occurs Reduction of torsion. The excessively high points of the ceramic substrate approach when heating on the pads, as the ceramic substrate is soft and, so to speak, "flows down". Another effect, which causes the reduction of torsion, is that only a few points, for example two or three, of the points of the substrate resting on the supports according to the invention are loaded by contact with the respective support and in comparison to the others freestanding or high-ranking points that have no contact with an edition, are pushed upward. On the freestanding points of the arrangement thereby a lesser or no pressure is exerted, whereby a bending moment arises. By this bending moment and the above-mentioned plastic flow the ceramic at bond temperature, the torsion of the substrate is reduced, or not further increased by preventing the slipping in the deepest center of gravity of the arrangement.

This effect of reducing the torsion is preferably achieved when the twisted ceramic substrate rests on at least two, preferably three, points on at least two, preferably three, of the supports according to the invention.

The inventive method, it is thus possible to produce reproducible one-sided and / or double-sided metallized ceramic substrates in series, which have a low torsion.

This makes it possible to produce ceramic substrates which are one-sidedly and / or double-sidedly metallized in series and which have constant characteristics, in particular with regard to torsion, flatness and orientation of the individual layers, as well as the quality of the metallic surfaces.

The present invention therefore relates in particular to a method according to the invention which has a large number of one-sided and / or double-sided metallized ceramic substrates with substantially constant properties of torsion, flatness, layer orientation and quality of the metallic surfaces.

In the following, the carrier used in the method according to the invention will first be discussed.

carrier

The method according to the invention for producing metallized ceramic substrates uses a carrier (also called a bond boat or bond ship). In this context, in the context of the present invention, a carrier denotes the entirety for accommodating the arrangements according to the invention. In particular, a carrier according to the present invention comprises at least one skeleton, hereinafter referred to as a support frame, which may optionally be provided with an insert plate, as well as at least one support for receiving the inventive arrangement (the Bond-Guts) and optionally at least one stop as a boundary ,

The elements of the carrier according to the invention are described in detail below.

The support frame forms the basic framework of the support according to the invention, on or on which the further support elements according to the invention are attached. In this case, the support frame can be configured for example in the form of a frame or interconnected struts.

The carrier according to the invention comprises at least one support for receiving a substrate or an arrangement, comprising at least a first metal layer and a ceramic substrate, the so-called bond good.

In a variant of the invention, the at least one support is arranged on the carrier so that the arrangement is inclined during positioning on the support of the carrier.

Therein, the at least one overlay is provided on at least one of the edge edges of the carrier and configured and arranged on the carrier such that an arrangement positioned thereon, comprising at least a first metal layer and a ceramic substrate, or a bond material to be positioned thereon, can be tilted is and / or is inclined. The inclination of the bond material or the arrangement can be achieved by the design of the mounted on the support at least one support and / or by the nature of their arrangement on the support, for example by their number, height and / or positioning on the support.

The attached to the support at least one support is designed such that the bond material to be positioned thereon is inclined. This can be achieved, for example, by the design or geometric design of the at least one support but also by the selected number, height and / or positioning of the at least one support on the support. This is preferably chosen such that an inclined plane is formed which is intended to correspond to the inclination of the bond material or the arrangement to be positioned thereon comprising at least a first metal layer and a ceramic substrate in such a way that it leads to a targeted alignment of the position comes from ceramic substrate and metal layer to each other.

In a further variant of the invention, the at least one support is arranged on the carrier such that the arrangement by inclining the entire carrier in process step (1) after positioning the assembly on the at least one support of the carrier and / or by inclining the carrier during of the process step (2) is inclined.

A combination of both variants is possible, namely tilting the arrangement by placing on at least one suitably arranged and designed edition and tilting of the entire carrier.

Furthermore, the at least one support provided on the support is dimensioned such that, on the one hand, the smallest possible contact surface and thus contact surface with the bond material or the components of the arrangement positioned thereon is impaired by interactions between the support and the ceramic substrate or metallized Keep substrate as low as possible. On the other hand, however, the dimensioning of the at least one overlay must be selected such that possible substrate size fluctuations during the bonding process and / or differences in the expansion coefficients between the support and the arrangement (ceramic substrate and metal layer) positioned thereon can be absorbed.

The supports according to the invention are preferably dimensioned so that the length of the respective support which extends at right angles to the outer edge with which the arrangement is positioned on the corresponding support (ie towards the middle of the bonding material) is not more than 10 mm, more preferably not more than 5 mm, more preferably not more than 3 mm.

Corresponding to this preferred maximum dimensioning of the supports, a preferred edge-side subregion of the arrangements according to the invention results, which extends up to 10 mm, preferably up to 5 mm, more preferably up to 3 mm at right angles from the outer edge of the arrangement (ie towards the center of the arrangement) ,

When using more than one overlay on a carrier according to the invention, the individual pads can each be the same or different dimensions.

In addition, the design of the at least one support is preferably to be chosen so that the arrangement positioned thereon before or during bonding slips into the desired position and the intended alignment of the individual components of the arrangement is made possible with each other. This is particularly preferred in the variants in which the inclination of the arrangement is achieved and / or assisted by the inclination of the at least one support.

At least one support for receiving the arrangement to be positioned thereon is provided on the support according to the invention. However, it is also possible to provide two, three, four, five, six or more identical or differently configured supports on the support. Preferably, two, three, four or five identical or differently configured pads are provided. More preferably, three, four or five identical or differently designed pads are provided. In an embodiment having only a single support for receiving the assembly to be positioned thereon, the positioned assembly must necessarily be supported by at least one further edge. It is conceivable here that the arrangement rests with the edge, which lies opposite the edge resting on the one support, on the support, for example on its insert plate and / or on at least one stop positioned on this opposite edge of the support. Such an embodiment is less preferred according to the invention.

A preferred embodiment is characterized in that the carrier at the edge comprises at least two supports on which the arrangement, comprising at least a first metal layer and a ceramic substrate, rests in at least two edge-side portions with two of its outer edges. In such an embodiment, therefore, two supports are preferably provided on two outer edges of the carrier. These two requirements may be the same or different. The two pads may be provided at opposite outer edges or adjacent outer edges of the carrier.

A further preferred embodiment is characterized in that the carrier comprises at least three editions on the edge, on which the arrangement, comprising at least a first metal layer and a ceramic substrate, rests in at least three peripheral partial areas with at least two of its outer edges. In such an embodiment, therefore, two supports are preferably provided on an outer edge of the support, in the case of substantially rectangular arrangements, preferably on one of the long edges (Longitudinal edges) of the carrier, and a further support is on an opposite edge, preferably also long edge, or on an adjacent outer edge of the carrier, in substantially rectangular arrangements preferably on one of the short edges (transverse edges) of the carrier provided. In this case, these three requirements may be the same or different.

If twisted substrates occur, embodiments are preferred in which the support according to the invention has at least four supports. By positioning per se already before the bonding process of twisted ceramic substrates and at least one metal layer on, for example, three of the at least four supports, in such an embodiment, a stable contact of the twisted substrate over three points on three of the supports is achieved. In this case, only the three resting on the supports points of the substrate are charged by the contact to the respective support and compared to the fourth freestanding, usually torsionally upstanding point that has no contact with a support, pushed up. On the freestanding point of the arrangement thereby a lesser or no pressure is exerted, whereby a bending moment arises. By this bending moment and the plastic flow of the ceramic at bonding temperature, the torsion of the substrate is reduced, or not further increased by preventing the slippage in the deepest center of gravity of the arrangement.

A further preferred embodiment is characterized in that the carrier comprises at least four supports on the edge, on which the arrangement, comprising at least a first metal layer and a ceramic substrate, rests in at least four edge-side partial areas with at least two of its outer edges. In such an embodiment, two supports are preferably provided on two opposite outer edges of the carrier, in the case of substantially rectangular arrangements, preferably on the two long edges (longitudinal edges). In this case, these four requirements may each be the same or different. It is also conceivable that two pads are each provided on two adjacent outer edges of the carrier.

A further preferred embodiment is characterized in that the carrier comprises at least five editions on the edge, on which the arrangement, comprising at least a first metal layer and a ceramic substrate, rests in at least five peripheral partial areas with at least three of its outer edges. In such an embodiment, two supports are preferably each provided on two opposite outer edges of the carrier, in the case of essentially rectangular arrangements preferably on the two long edges (longitudinal edges), and a further support is placed on a further outer edge of the carrier, with essentially rectangular arrangements preferably on one of the short edges (transverse edges), provided. These five editions can each be the same or different.

The following table shows by way of example possible arrangements of the at least one support on the support, without the invention being limited thereto: Number of copies Number of edges on which the pads are intended Selection of the edges on which the pads are intended * 1 1 long or short ₂ 1 long or short 2 2 long and short (one overlay each on adjacent edges) 2 2 long and long or short and short (one overlay each on opposite edges) 3 1 long or short long (2 editions) and 3 2 long (1 edition) (on opposite edges) 3 2 short (2 editions) and short (1 edition) (on opposite edges) 3 2 long (1 edition) and short (2 editions) (on adjacent edges) 3 2 long (2 editions) and short (1 edition) (on adjacent edges) 3 3 long (1 edition) and long (1 edition) and short (1 edition) 3 3 long (1 edition) and short (1 edition) and short (1 edition) 4 1 long or short 4 2 long and short (two overlays each on two adjacent edges) 4 2 long and long or short and short (two overlays each on two opposite edges) 4 2 long and short (three editions on one long edge and one edgeband on a short edge) 4 2 long and short (one overlay on one long edge and three overlays on a short edge) 4 3 long (2 editions) and long (1 edition) and short (1 edition) 4 3 long (1 edition) and long (1 edition) and short (2 editions) 4 3 long (2 editions) and short (1 edition) and short (1 edition) 4 3 long (1 edition) and short (1 edition) and short (2 editions) 4 4 long (1 edition) and long (1 edition) and short (1 edition) and short (1 edition) 5 1 long or short 5 2 1 and 4 pads on two long or two short edges (opposite edges) 5 2 long (4 editions) and short (1 edition) (adjacent edges) 5 2 long (1 edition) and short (4 editions) (adjacent edges) 5 2 2 and 3 pads on two long or two short edges (opposite edges) 5 2 long (3 editions) and short (2 editions) (adjacent edges) 5 2 long (2 editions) and short (3 editions) (adjacent edges) 5 3 long (2 editions) and long (2 editions) and short (1 edition) 5 3 long (2 editions) and long (1 edition) and short (2 editions) 5 3 short (2 editions) and short (2 editions) and long (1 edition) 5 3 short (1 edition) and short (1 edition) and long (3 editions) 5 3 long (1 edition) and long (1 edition) and short (3 editions) 5 4 long (2 editions) and long (1 edition) and short (1 edition) and short (1 edition) 5 4 long (1 edition) and long (1 edition) and short (2 editions) and short (1 edition) 6 2 long or short in each case 3 supports (opposite edges) 6 2 long and short in each case 3 pads (adjacent edges) 6 3 long (2 editions) and long (2 editions) and short (2 editions) 6 3 long (2 editions) and long (2 editions) and short (1 edition) and short (1 edition) * In a substantially square arrangement, all edges are substantially equal in length, so that a distinction between long and short edge here serves the distinction between opposite and adjacent edges.

Corresponding exemplary possibilities for arrangement also result for the at least one stop provided on the carrier. In addition, embodiments of the supports and stops according to the invention may also be provided in each case, which at the same time fulfill the function of support and stop, as explained below and by way of example in FIG 4 shown. In addition, it is possible that the exemplary positions shown in the above table are not limited to editions or But to provide an appropriate combination of constraints and attacks each without double function (or even in combination with such dual-function pads / stops).

Other combinations and arrangements are possible and also encompassed by the present invention.

Basically, in a first variant of the carrier due to the design, number, height and / or positioning of the attached at least one edition already predetermine the inclination of the arrangement to be positioned on it, whereby it in the positioning of the individual components of the arrangement to their orientation the carrier comes.

In principle, however, the at least one support arranged on the support for receiving the components of the arrangement can also be inclined only after the positioning of the individual components of the arrangement, for example by adjusting the height and / or position (inclination) of the at least one support, so that it comes to a positioning of the individual components of the arrangement.

In a second variant, the arrangement undergoes an inclination after positioning on the at least one support of the support by tilting the entire support, as already described above.

Preferably, the arrangement undergoes, after being positioned on the at least one support of the support, an inclination by the supports and by the inclination of the entire support.

So that the spatial height of the support for the passage in the bonding furnace is not too large, the inclined support and / or the attached thereto at least one inclined support can be approximated to a horizontal position after positioning and aligning the components of the arrangement.

In this case, the inclination and the choice of materials of the wearer are to be chosen so that it does not come to a slipping of the individual components of the arrangement in the case where the intended approach of the carrier to a horizontal position.

In principle, the shape and size of the at least one support is to be designed so that the arrangement positioned thereon does not come into contact with other components of the support due to a bending, in particular a bimetallic deflection occurring, for example, due to the bonding process.

A bimetallic deflection usually occurs in the second bonding step. Therefore, it is particularly important to precisely align the ceramic substrate and metal layer with each other before and during the second bonding step, i. H. in the process step (4) according to the invention.

Examples of possible embodiments of provided on the carriers according to the invention at least one edition shows 3 ,

In the variant according to the invention in which the inclination of the arrangement is effected by the at least one support attached to the support, the provided at least one support is attached to the support in such a way that an inclination of the arrangement positioned thereon is effected or can be effected. Due to the inclination, during or after the positioning of the ceramic substrate layer and the metal layer, the individual layers are positioned relative to one another.

So that the arrangement remains fixed on the at least one support of the carrier, it is provided that the carrier has at least one boundary in the form of at least one stop or at least one edge as boundary on the edge. Such a limitation is provided on at least one of the edge of the carrier lying in each case by the inclination to which the arrangement slips due to the inclination of the carrier or the supports. If the arrangement comprising the at least one metal layer and the ceramic substrate is then positioned on the at least one support of the support, the individual layers of the arrangement can slip following the inclination caused by the supports and thus abut the boundary of the support. As a result, a clearly defined positioning of the individual layers of the arrangement is achieved, which thus also have a clearly defined positioning relative to one another.

In principle, it is possible that the carrier according to the invention has at least one stop for limiting the carrier. However, it is also possible to have two, three, four, five, six or more each provided identically or differently designed attacks on the carrier. Preferably, one, two or three identically or differently configured stops are provided. More preferably, two or three identically or differently configured stops are provided. More preferably, one, two or three identically designed stops are provided. Even more preferably, two or three identically configured stops are provided.

A preferred embodiment is characterized in that the carrier at the edge has at least one stop on at least one of the edges located below by the inclination of the positioned arrangement. At least two stops are preferably provided on at least one of the edges located below by the inclination of the positioned arrangement. More preferably, two stops are provided on one of the lower edges of the positioned arrangement, preferably on the long lower edge (longitudinal edge). In this case, these two attacks can be the same or different.

In a further preferred embodiment, at least two stops are provided on at least two of the edges located below by the inclination of the positioned arrangement, a stop on the long underlying edge (longitudinal edge) of the positioned arrangement is preferably provided, and a second stop is on the short underlying one Edge (transverse edge) of the positioned arrangement provided. In this case, these two stops can each be the same or different.

In a further preferred embodiment, at least three stops are provided on at least two of the edges located below by the inclination of the positioned arrangement, two stops on the long underlying edge (longitudinal edge) of the positioned arrangement are preferably provided, and a third stop is on the short one below Edge (transverse edge) of the positioned arrangement provided. In this case, these three stops can each be the same or different.

In this case, acting as a boundary of the carrier stops with respect to their shape, dimension and positioning at the edge edges of the carrier can be configured almost arbitrarily, as long as they are able, the inclined arrangement comprising at least a first metal layer and a ceramic substrate after To fix the inclination of the arrangement on the supports of the wearer. Conceivable are various geometric surfaces such. As rectangular, round, triangular, etc. Typically, these are projected upwards or extruded, so that there are columns with the respective base area.

In general, the boundary is designed so that it is provided in the sense of a projection or stop on the support side of the arrangement to be positioned on the edge of the carrier and protrudes vertically beyond the carrier. In this case, the height of the boundary or of the at least one stop is to be selected such that the arrangements positioned on the at least one support do not have the stops and thus of the at least one support due to a deflection, for example a bimetallic deflection resulting from the bonding process slip. However, the stops are preferably designed as narrow as possible, so that they have a small contact area to the bond Good.

In principle, it is possible in all of the embodiments described above that the stops are designed so that they simultaneously fulfill the function of the support or the supports are designed so that they simultaneously act as a limiting stop. Examples of such embodiments, which represent a combination of stop and support, shows by way of example 4 ,

In particular, an embodiment is preferred in which at least one, preferably two stops on the long underlying edge (longitudinal edge) of the positioned arrangement are provided and wherein a further stop on the short underlying edge (transverse edge) of the positioned arrangement is provided, and wherein at the At least one, preferably two pads are provided at the long underlying edge opposite long edge, and wherein the at least one, preferably the two stops on the long lower edge are simultaneously formed as a support. A corresponding embodiment is exemplary in FIG 2c and 2d shown. The respective conditions, stops and the combination of support and stop can each be the same or different. An embodiment wherein both a longitudinal and a transverse edge by inclination will form a lower edge in FIG 2 B and 2d outlined.

In comparison with the method according to the invention using the carriers according to the invention, positioning of the individual layers of the arrangement relative to one another is not achieved in the prior art methods in which no inclination of the carrier is provided. In the production of metallized ceramic substrates, therefore, either very precise positioning of the individual metal layers and of the ceramic layer must be realized in the prior art methods, or the resulting metallized ceramic substrates have an inaccuracy in the positioning of the individual layers relative to one another, which is for example can lead supernatant metal layers in relation to the ceramic substrate. Such metallized ceramic substrates are then rejected after their production or have a wide unusable technical edge.

Assuming a substantially rectangular bonding material, there are several possibilities for realizing an inclination of the bonding material positioned on the support in the sense of the present invention.

The 2 shows a possible rectangular geometry of the bond material, wherein the inclination of the same about the edge 5 (see. 2a and 2c ) or around the edges 8th and 9 (see. 2 B and 2d ) possible are.

In the first in 2a and 2c In the embodiment shown, the substantially rectangular plane of the bonding material only becomes over an edge 5 tilted, so that according to the inclination of the same two corners 6 and 7 located on a substantially identical lower level.

In the in 2 B and 2d In the illustrated embodiment, the substantially rectangular plane of the bond material becomes two edges 8th and 9 tilted so that in total only one corner 10 same at the lowest level.

In the context of the present invention, the in 2 B and 2d embodiment shown preferred because it allows a more accurate positioning of the individual components of the arrangement to each other due to the two-sided inclination.

According to the invention, the term "level" is preferably understood to mean the lateral plane in which the substantially rectangular plane of the bond material positioned on the carrier can at least partially be located. Here, the "initial level" (the so-called zero level), to which all other information is relatively related, the level (ie the level), which is spanned by the bond good in un-inclined form, in which thus the in Substantially rectangular plane of the material positioned on the carrier first extends (horizontally) (step (1) and (4)) before it undergoes a tilt, and which usually runs at the level of the highest edition. All other terms of the "level" are to be understood relative to this initial level. Thus, in particular a "lower level" is understood to mean a lateral plane (ie a horizontally mounted plane) which is displaced in the vertical direction parallel to the plane of the initial level. Preferably, the lower level is thus lowered vertically relative to the starting level. Furthermore, in particular, a "lowest level" is understood to mean the lateral plane (ie the horizontally mounted plane) which is displaced in the vertical direction parallel to the plane of the output level and has the highest, ie greatest, relative (vertical) shift relative to the starting level , in which there is still a corner of the material positioned on the carrier Bond. Preferably, the lowest level is thus also lowered relative to the starting level vertically. In this case, the lowest level always has a greater vertical displacement relative to the initial level than the lower level (according to the invention, the cases where there is only a relative vertical displacement is referred to as a case of a lower level, in which case the lower level equal to the lowest level). That from this around the axes of rotation 8th and 9 inclined bond good then exhibits an inclination, which by the in 5 illustrated angle α, β and γ will be described.

Depending on the choice of the angle α and β, an angle γ, which is generally 0.5 to 45 °, preferably 0.5 to 40 °, more preferably 0.5 to 35 °, more preferably 1 to 30 °, further preferably 1 and 25 °. The resulting angle γ must be large enough that alignment by slipping of at least one metal layer and the ceramic substrate is possible, but again should not be too large, otherwise the height of the carrier used is too large and in turn the height of the used furnace, such as in particular a tunnel oven, would have to be increased.

Due to the present inclination of the bonding material positioned on the carrier, after the positioning of the ceramic substrate and the at least one metal layer on the supports of the carrier according to the invention, the individual metal layers or the ceramic substrate become aligned with slippage, so that a with regard to the alignment of metal layers and ceramic substrate to each other defined arrangement is achieved. Preferably, the individual layers or the substrate slip the Following the inclination of the supports placed on the support following until they hit a boundary (eg in the form of the stops according to the invention).

In the in 2a illustrated embodiment, in which the positioned on the carrier bond Good over the edge 5 tilting, a boundary may be sufficient at the downwardly sloping edge to fix the assembly comprising at least a first metal layer and a ceramic substrate.

The boundary can be formed from a projecting over the carrier in the direction of the arrangement projection or stop, which is either integrally formed and therefore continuous, or is interrupted and thus from a plurality of individualized, d. H. at least two individual projections or stops.

In the case of the embodiment of the 2 B the corresponding boundary can also be formed by a projecting projection or stop which is located on the two adjacent inclined edges of the carrier and on the point below 10 hinläuft. Optionally, it is also possible that the limitation in the embodiment according to 2 B is formed of two or more, for example two, three, four, five or six, short and separate projections or stops, wherein the projections or stops are provided on the two downwardly inclined, adjacent edges of the carrier.

The carrier, which is used in the method according to the invention, may have an insert plate, which can be inserted into the support frame of the carrier. The insert plate preferably has a thickness of in particular 0.1 to 10 mm, preferably 0.15 to 5 mm, more preferably 0.25 to 3 mm. In this case, the insert plate can be designed so that the surface is completely closed or partially open below the positioned on the carrier assembly. If no insert plate is inserted into the support frame, the surface is open below the positioned on the carrier assembly. For example, a completely closed insert plate can be provided, or a type of perforated plate or a bottom grid. An open embodiment without insert plate is less preferred.

A closed or partially open embodiment of the carrier can be obtained either by forming a correspondingly shaped support frame from the corresponding solid material or by inserting a corresponding insert plate or a grid into a support frame in the form of a frame or linkage.

The insert plate of the carrier according to the invention preferably consists of a high-temperature-resistant material, which is inert and / or not wettable at the applied temperatures of the bonding process. Here, basically the same materials can be used, as defined below for the carrier according to the invention. However, it is also possible to use another high temperature resistant material, such as a ceramic material. Preferably, an oxide ceramic material such. As alumina, or a carbide, nitridic, silicic or metallic material used.

The carrier according to the present invention comprises as main components the support framework, at least one support attached to the support, as defined above, and optionally at least one stop, as defined above, and optionally an insert plate, as defined above.

Corresponding carriers are also generally referred to as bond boats, bond ships or the like in the field of direct metal bonding.

The supports of the present invention can be formed by individual, independent components and variably assembled. However, they can also be firmly joined together to form a quasi-"one-piece" carrier which has the functional elements of the at least one overlay and the at least one stop defined herein.

The support used in the method according to the invention is preferably made of a material having high heat resistance, which is inert and / or non-wettable at the applied temperatures of the bonding process. Materials for the support according to the invention are, in particular, materials selected from the group consisting of graphite, mullite, steatite, cordierite, ZrO ₂ , Al ₂ O ₃ , AlN, BN, ZrN, Si ₃ N ₄ , SiC and mixtures thereof Question.

Also for the individual support elements according to the invention, such as support frame, insert plate, the at least one support and the at least one stop, these materials are suitable. The individual elements can each be formed from the same or different materials.

Also, the carrier itself or the - next to the insert plate - provided various support elements may be formed in addition to the aforementioned materials also from another high temperature resistant material, such as a ceramic material such. B. preferably from an oxide ceramic material such. As alumina, or a carbide, nitridic, silicic or metallic material.

Furthermore, high-temperature-resistant metals, in particular for the support or the support framework, the stops and the bearing surfaces, in particular alloyed steel, preferably Inconel, or an alloy comprising a constituent selected from the group consisting of molybdenum, titanium, chromium, nickel , Tungsten or mixtures thereof, in question.

In the case of using SiC for the at least one overlay of the carrier according to the invention, which is particularly preferred in the context of the present invention, recrystallized SiC, nitride-bonded SiC, isostatically pressed SiC, Si-filtered SiC, pressure-sintered SiC or liquid-phase sintered SiC come into question.

It is further preferred if the at least one support and / or the at least one stop of the support can optionally be reused after cleaning.

The dimension of the support can be chosen within wide ranges and depends on the orders of magnitude of the metallized ceramic substrates to be produced and the bonding furnaces used. Suitable dimensions of the carrier are between 20 × 20 mm ² and 300 × 350 mm ² , wherein the shape of the carrier is preferably either substantially square or substantially rectangular.

In the bonding furnace, which is generally a tunnel kiln or continuous furnace, are basically one- or multi-storey and single or multi-row constructions of the carrier conceivable.

In the context of the present invention, embodiments are therefore also provided in which carriers are used which are designed for the simultaneous bonding of a plurality of arrangements. With such a combination of a plurality of mounting areas, the size described above increases according to the number of layouts. These carriers then have a plurality of support structures arranged one above the other and / or next to one another with the support and stop elements mounted thereon, on each of which an arrangement to be bonded is positioned.

A one-story construction is preferred.

In the bonding furnace, the assembly, which rests on the supports of the carrier, is usually passed through the furnace at a constant transport speed and thus brought to a temperature at which joining of metal foil and ceramic substrate takes place, and subsequently after passing through the heating zones of the furnace cooled again.

In the bonding furnace, the lowest point of the carriers used according to the invention, which is formed by the inclination, can be in the transport direction both at the front and at the rear.

Engobe / release agent

During the bonding process, the metal layer disposed on the ceramic substrate melts superficially. If contact occurs at this time with other surfaces, such as the carrier or the supports and / or stops attached to the carrier, there is a possibility that defects in the generated metal coating on the ceramic substrate will occur.

In order to avoid such defects on the metal surface, it is known from the prior art to provide so-called release agents on the support.

Therefore, in a preferred embodiment of the present invention, a carrier is used, which at the coming into contact with the bond Good surfaces, for. B. the surfaces of the pads and / or the attacks, is provided with a release layer such that during bonding a connection of the metal layer possibly adjacent to this separation layer with the carrier or the supports and / or attacks does not occur.

The separating layer optionally provided on the carrier elements may comprise a material which is selected from the group consisting of oxidic, nitridic, silicidal or carbide ceramics and salts.

In particular, the release layer comprises a material selected from the group consisting of mullite, steatite, cordierite, Al ₂ O ₃ , TiO ₃ , ZrO ₂ , MgO, CaO, yttria, SnO ₂ , CaCO ₃ , BN, ZrN, graphite , Zirconia-reinforced alumina (ZTA), BeO, Al ₂ TiO ₅ , CaSO ₄ , MgSO ₄ , BaSO ₄ and mixture of the aforementioned materials.

Furthermore, it is preferred that the separating layer comprises a material which is selected from the group consisting of mullite, steatite, cordierite, Al ₂ O ₃ , ZrO ₂ , MgO, Al ₂ TiO ₅ , SnO ₂ , yttrium oxide, BaSO ₄ , MgSO ₄ and mixture of the aforementioned materials.

The separating layer optionally used on the carrier elements has in particular a thickness of 10 to 1000 .mu.m, preferably 25 to 750 .mu.m, more preferably 50 to 500 .mu.m, more preferably 75 to 400 .mu.m, more preferably 100 to 350 .mu.m. Furthermore, it is preferred if the release layer has a porosity, i. H. a ratio of the pore volume to the volume of solids of greater than 10%, more preferably greater than 15%, more preferably greater than 20%. The particle size of the particles forming the separating layer is generally less than 50 μm, preferably less than 40 μm, more preferably less than 35 μm, more preferably less than 30 μm.

The separating layer provided according to the invention may, for example, also be provided with a colored additive. The use of such a colored additive has the advantage that it is easy to see visually whether the release layer has a defect and is thus to be replaced if necessary. The colored additive may, for example, be chromium oxide.

If, after the bonding process and after removal of the assembly from the support, particles of the release layer still adhere to the metal layer, they can then be removed by a suitable method, for example by a mechanical process (eg brushing) or by a chemical process (eg, etching a thin surface layer).

Further embodiments of the separation layer can the DE 10 2004 056 879 A are taken from the relevant disclosure by reference in the present invention.

In order to avoid a possible adhesion of the metal layer and supports, the position of the at least one support of the support according to the invention can be chosen such that in combination with a correspondingly adapted metal punching image (eg copper punched image) in the region the respective requirements no metal (eg Kuper) is present. This can z. For example, the metal (eg, copper) may be unlatched during punching / chopping so that there is no metal (eg at the corners of the metal layer) at the locations where the metal layer contacts the pads of the substrate (e.g. eg copper) is more present. As a result, there is no contact between the supports of the carrier and the metal surface during bonding. The substrates can no longer bond. This is particularly important in the automation of loading and unloading at the inlet and outlet of the bonding furnace.

arrangement

The inventive method is suitable for producing metallized ceramic substrates, which are also the subject of the present invention. The arrangements according to the invention may have, in addition to the at least one metal layer and the ceramic substrate, further layers, such as a solder layer.

The ceramic substrate may, for example, be substrates of aluminum oxide, aluminum nitride, silicon nitride or silicon carbide. For the ceramic layer, for example, an alumina ceramic (Al ₂ O ₃ ) with a content of zirconium oxide (ZrO ₂ ) in the order of about 2-30% is suitable. or an aluminum nitride ceramic, for example with yttrium oxide as additive, or a silicon nitride ceramic, wherein the aluminum nitride ceramic and / or the silicon nitride ceramic, for example, may have an oxidic surface layer, for example a surface layer of aluminum oxide. The thickness of the ceramic layer is preferably in the range between 0.2 and 1.5 mm.

The at least one metal layer on the ceramic substrate may be formed starting from metal sheets or metal foils having a thickness of generally 100 to 1000 μm, preferably 125 to 750 μm, more preferably 150 to 700 μm, more preferably 175 to 600 before the bonding step have μm.

Before the process according to the invention, the metal foils or sheets can be oxidized on both sides in a known manner.

The method according to the invention is suitable for the production of metal-ceramic substrates (MCS) and substrates which are produced by means of direct copper bonding (DCB), direct aluminum bonding (DAB) or active metal bonding (AMB).

The resulting arrangements differ from those of the prior art in an improved positional accuracy of the metal layers and the ceramic substrate to each other and / or in improved flatness, as well as a reduced torsion.

Another object of the present invention is a support for producing a metallized ceramic substrate, which is used in the method described above. With regard to the specific embodiments of the carrier according to the invention, reference is therefore made to the above statements.

In particular, the support according to the invention is used in an oven, preferably in a tunnel kiln or continuous furnace, for the production of metallized ceramic substrates, wherein the furnace, in particular the tunnel kiln or continuous furnace, for a heat treatment of treated with at least one tunnel-like furnace chamber and at least one Heating device is provided for heating the at least one furnace chamber and has a transport unit which transports the carrier according to the invention through the furnace chamber.

The carrier may comprise at least two parts, wherein the carrier comprises at least one support for receiving the at least one metal layer and the ceramic substrate and a tool carrier. About the tool carrier, the carrier is attached to the mounted thereon at least one support with a transport unit, which allows transport of the carrier through the tunnel kiln.

Embodiments of carriers according to the present invention are also encompassed by the present invention, which are designed for a plurality of substrates, for example two, three, four, five or six arrangements, wherein different arrangement possibilities of individual carriers in the oven in the 8th are shown.

Description of the figures

The present invention will now be explained in more detail with reference to the following description of the figures.

The reference numerals used in the description of the figures have the following meaning:

LIST OF REFERENCE NUMBERS

1

Arrangement comprising at least a first metal layer and a ceramic substrate or bonding material,

2, 3

Carrier of the prior art,

4

Carrier (according to the invention),

5, 8, 9

Axes of rotation

6, 7, 10, 11

Corner points of a substantially rectangular arrangement, comprising at least a first metal layer and a ceramic substrate / a substantially rectangular Bond Guts 1 .

12 ', 12' ', 12' '', 12 '' ''

by inclination formed height difference to zero level,

13 ', 13'',13''', 13 '''', 13 ''''',13''''''

Pads,

14 ', 14' ', 14' '', 14 '' '', 14 '' '', 14 '' '' ''

Stops / limits

15 ', 15' '

height adjustable feet and

16 ', 16' '

Combination of stop and support

It shows the 1 two conventional prior art designed as bond boats carrier, with which two-sided metallized substrates are prepared in a two-stage process. The already one-sided bonded substrates 1 become so on carriers 2 . 3 fixes that there is no direct contact of the already bonded copper or ceramic surface with other surfaces, such as the conveyor belt, in the second bonding step. This is done for example by the use of carriers in which the one-side bonded substrates 1 only at the edges 2 resting on a support (cf. 1a ) or over narrow runs 3 on the short sides of the substrates 1 be carried (cf. 1b ).

Furthermore, the shows 2 a carrier 4 , on which at least at one of its edge edges at least one support 13 ' . 13 '' . 13 ''' . 13 '''' . 13 ''''' . 13 '''''' is provided, on which the arrangement of method step ( 1 ) or the bond good 1 in at least one edge-side portion rests with at least one of its outer edges and wherein in the embodiment shown here, the substantially rectangular inclined Bond-Good 1 in the 2a over an edge 5 is inclined so the vertices 6 and 7 of the bond material are in a level below the initial level (zero level) of the bond material. In the 2 B is the bond good 1 on the at least one edition 13 ' . 13 '' . 13 ''' . 13 '''' . 13 ''''' . 13 '''''' of the carrier 4 a total of two edges 8th and 9 inclined so the vertices 10 and 11 the Bond good 1 below the initial level (the zero level) of the bond good 1 to find oneself. The arrows shown 12 ' . 12 '' . 12 ''' and 12 '''' show the slope of the bond good 1 at. It can also be on the edge of the carrier 4 at least one stop 14 ' . 14 '' . 14 ''' . 14 '''' . 14 ''''' . 14 '''''' be provided. It is also conceivable that at least one of the positions 13 ' . 13 '' . 13 ''' . 13 '''' . 13 ''''' . 13 '''''' respectively. 14 ' . 14 '' . 14 ''' . 14 '''' . 14 ''''' . 14 '''''' a pad is provided, which simultaneously fulfills the function of a stop.

It is both in 2a as well as in 2 B the number and positioning of the pads shown here 13 ' . 13 '' . 13 ''' . 13 '''' . 13 ''''' . 13 '''''' , as well as the attacks 14 ' . 14 '' . 14 ''' . 14 '''' . 14 ''''' . 14 '''''' to be understood merely as an example illustration. The exact positioning at the edges and the respective total number and distribution of supports and / or attacks can be varied in a suitable manner.

2c and 2d show a further embodiment, wherein at the position 16 ' and 16 '' a stop is provided, which simultaneously fulfills the function of a support.

In the context of the present invention, a zero level is understood to mean the plane which is spanned by the bond material in an un tilted form.

The 3 shows possible geometrical configurations of editions 13 ' . 13 '' . 13 ''' . 13 '''' . 13 ''''' . 13 '''''' without being limited thereto.

The 4 shows possible geometrical configurations of supports that simultaneously fulfill the function of a stop, 16 ' . 16 '' without being limited thereto.

The 5 shows an inclined arrangement, comprising at least a first metal layer and a ceramic substrate (Bond-Gut) 1 in which the inclination of the bond good 1 through the illustrated angles α, β and γ results. By selecting suitable angles α and β results in an angle γ, which is a measure of the deviation of the inclined bond material 1 from the zero level represents. The angle γ in the context of the present invention may be 0.5 to 40 °, preferably 0.5 to 35 °, more preferably 0.5 to 30 °, more preferably 1 to 25 °, further preferably 1 and 5 °.

Furthermore, the shows 6 an embodiment of a carrier 4 that is designed to be the Bond Good 1 inclined, the inclination of the bond good 1 through at the corners of the substantially rectangular bond material 1 located height-adjustable feet 15 ' . 15 '' and 15 ''' is supported.

The 7 shows an embodiment of a carrier 4 that is designed to be the Bond Good 1 inclined, the three stops 14 ' . 14 '' . 14 ''' having, at the long edge lying down through the inclination (Longitudinal edge) two boundaries 14 ' and 14 ''' and at the short edge lying by the inclination (transverse edge) a stop 14 '' is provided.

The 8th shows a variety of possible arrangements of the support in the oven, in particular in a tunnel oven.

The inventive method makes it possible to connect at least one ceramic substrate at the top and / or top and bottom in a single-stage or two-stage process run, each with a metal layer. In this case, a high positional accuracy of the layers is achieved to each other and achieves a reproducible improved flatness of the resulting arrangement and reduces the torsional tendency of the substrates.

QUOTES INCLUDE IN THE DESCRIPTION

This list of the documents listed by the applicant has been generated automatically and is included solely for the better information of the reader. The list is not part of the German patent or utility model application. The DPMA assumes no liability for any errors or omissions.

Cited patent literature

• US 3744120 [0003]
• US 3994430 [0003]
• EP 0085914 A [0003]
• DE 2319854 A [0003]
• DE 102004056879 A [0007, 0140]
• DE 102010023637 A [0009, 0009]
• WO 2014/049414 [0010]
• US 2007/261778 [0010]
• WO 2004/032593 [0014, 0014, 0014]
• WO 2011/104222 [0015, 0015]

Claims (11)

A method for producing a metallized ceramic substrate, comprising the following method steps: (1) positioning an assembly comprising at least a first metal layer and a ceramic substrate on a support; (2) heating the from the process step ( 1 ) to a temperature, so that it comes to a composite of the ceramic substrate and the adjacent at least one metal layer by bonding to form a metallized ceramic substrate, characterized in that - the carrier in step (1) at least one its edge edges has at least one support on which the arrangement of method step (1) rests in at least one peripheral portion of the arrangement with at least one of its outer edges, and - the at least one support is arranged on the carrier so that the arrangement during positioning the support of the support is inclined and / or - the support with the at least one support in process step (1) is tilted after the positioning of the arrangement on the at least one support of the support and / or during the process step (2), - and wherein the Carrier on at least one of its edge edges at least one Be Having boundary in the form of at least one stop or at least one edge. The method of claim 1, comprising the additional method steps (3) rotating the metallized ceramic substrate from step (2) about a rotational axis parallel to its longitudinal or transverse edge; (4) positioning an assembly comprising the rotated metallized ceramic substrate of step (3) and at least one further metal layer on a support as defined in claim 1; (5) heating the assembly resulting from process step (4) as defined in process step (2) of claim 1. A method according to claim 1 or 2, characterized in that the carrier is substantially rectangular in shape and has at least one support which is arranged such that when positioning a substantially rectangularly shaped arrangement on the support of the carrier, the arrangement over an edge 5 is tilted, giving a total of two corners of the rectangular arrangement 6 and 7 result, which are located after the inclination on a substantially identical lower level. Method according to one of claims 1 to 3, characterized in that the carrier is substantially rectangular in shape and has at least two supports, which are arranged such that when positioning a substantially rectangular arrangement on the supports of the support, the arrangement over two edges 8th and 9 is tilted, leaving a total of only one corner of the right-angled arrangement 10 is at the lowest level. Method according to one of claims 1 to 4, characterized in that in the process steps (1) and / or (2), and optionally (4) and / or (5), provided for the inclination of the arrangement is designed so that it an alignment of the arrangement comes and / or arrange the individual components of the arrangement comprising at least one metal layer and the ceramic substrate to each other. Method according to one of claims 1 to 5, characterized in that the carrier edge-side comprises at least two pads on which the arrangement of step (1), and optionally (4) rests in at least two edge-side portions with at least two of its outer edges. Method according to one of claims 1 to 6, wherein at least one of the stops at the same time as a support for the arrangement of step (1), and optionally (4) is formed. Arrangement comprising at least one metal layer and a ceramic substrate, obtainable by the method according to one of claims 1 to 7. A carrier for producing a metallized ceramic substrate, characterized in that - the carrier on at least one of its edge edges at least one support for an arrangement comprising at least a first metal layer and a ceramic substrate substrate, wherein the at least one support such is arranged on the support, that the arrangement is inclined and / or tilted when positioning on the support of the carrier, and / or - The support is inclined and / is tilted, - and wherein the carrier has at least one edge edge in the form of at least one stop or at least one edge. Carrier according to claim 9, characterized in that the carrier in an oven, in particular in a tunnel kiln or continuous furnace, is used for the production of metallized ceramic substrates, wherein the furnace for a heat treatment of treated with at least one tunnel-like furnace chamber and at least one Heating device is provided for heating the at least one furnace chamber and has a transport unit which transports the carrier through the furnace chamber. Carrier according to one of claims 9 or 10, characterized in that the carrier edge-side comprises at least two pads on which the arrangement comprising at least a first metal layer and a ceramic substrate rests in at least two edge-side portions with at least two of its outer edges and wherein the individual components of the arrangement at the at least one edge-side boundary of the carrier, in the form of at least one stop or at least one edge, to each other.

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