WO2000006333A1 - Method for brazing by solder reflow electronic components and brazing device therefor - Google Patents

Method for brazing by solder reflow electronic components and brazing device therefor Download PDF

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Publication number
WO2000006333A1
WO2000006333A1 PCT/FR1999/001657 FR9901657W WO0006333A1 WO 2000006333 A1 WO2000006333 A1 WO 2000006333A1 FR 9901657 W FR9901657 W FR 9901657W WO 0006333 A1 WO0006333 A1 WO 0006333A1
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WO
WIPO (PCT)
Prior art keywords
support
components
brazing
fluxing
atmosphere
Prior art date
Application number
PCT/FR1999/001657
Other languages
French (fr)
Inventor
Claude Carsac
Gilles Conor
Thierry Sindzingre
Denis Verbockhaven
Original Assignee
L'air Liquide, Societe Anonyme Pour L'etude Et L'exploitation Des Procedes Georges Claude
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by L'air Liquide, Societe Anonyme Pour L'etude Et L'exploitation Des Procedes Georges Claude filed Critical L'air Liquide, Societe Anonyme Pour L'etude Et L'exploitation Des Procedes Georges Claude
Priority to CA002338157A priority Critical patent/CA2338157A1/en
Priority to JP2000562170A priority patent/JP2002521207A/en
Priority to BR9912560-9A priority patent/BR9912560A/en
Priority to KR1020017001258A priority patent/KR20010053616A/en
Priority to EP99929437A priority patent/EP1100644A1/en
Priority to AU46253/99A priority patent/AU4625399A/en
Publication of WO2000006333A1 publication Critical patent/WO2000006333A1/en

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Classifications

    • HELECTRICITY
    • H05ELECTRIC TECHNIQUES NOT OTHERWISE PROVIDED FOR
    • H05KPRINTED CIRCUITS; CASINGS OR CONSTRUCTIONAL DETAILS OF ELECTRIC APPARATUS; MANUFACTURE OF ASSEMBLAGES OF ELECTRICAL COMPONENTS
    • H05K3/00Apparatus or processes for manufacturing printed circuits
    • H05K3/30Assembling printed circuits with electric components, e.g. with resistor
    • H05K3/32Assembling printed circuits with electric components, e.g. with resistor electrically connecting electric components or wires to printed circuits
    • H05K3/34Assembling printed circuits with electric components, e.g. with resistor electrically connecting electric components or wires to printed circuits by soldering
    • H05K3/3494Heating methods for reflowing of solder
    • BPERFORMING OPERATIONS; TRANSPORTING
    • B23MACHINE TOOLS; METAL-WORKING NOT OTHERWISE PROVIDED FOR
    • B23KSOLDERING OR UNSOLDERING; WELDING; CLADDING OR PLATING BY SOLDERING OR WELDING; CUTTING BY APPLYING HEAT LOCALLY, e.g. FLAME CUTTING; WORKING BY LASER BEAM
    • B23K1/00Soldering, e.g. brazing, or unsoldering
    • B23K1/012Soldering with the use of hot gas
    • HELECTRICITY
    • H05ELECTRIC TECHNIQUES NOT OTHERWISE PROVIDED FOR
    • H05KPRINTED CIRCUITS; CASINGS OR CONSTRUCTIONAL DETAILS OF ELECTRIC APPARATUS; MANUFACTURE OF ASSEMBLAGES OF ELECTRICAL COMPONENTS
    • H05K2203/00Indexing scheme relating to apparatus or processes for manufacturing printed circuits covered by H05K3/00
    • H05K2203/08Treatments involving gases
    • H05K2203/087Using a reactive gas
    • HELECTRICITY
    • H05ELECTRIC TECHNIQUES NOT OTHERWISE PROVIDED FOR
    • H05KPRINTED CIRCUITS; CASINGS OR CONSTRUCTIONAL DETAILS OF ELECTRIC APPARATUS; MANUFACTURE OF ASSEMBLAGES OF ELECTRICAL COMPONENTS
    • H05K2203/00Indexing scheme relating to apparatus or processes for manufacturing printed circuits covered by H05K3/00
    • H05K2203/09Treatments involving charged particles
    • H05K2203/095Plasma, e.g. for treating a substrate to improve adhesion with a conductor or for cleaning holes
    • HELECTRICITY
    • H05ELECTRIC TECHNIQUES NOT OTHERWISE PROVIDED FOR
    • H05KPRINTED CIRCUITS; CASINGS OR CONSTRUCTIONAL DETAILS OF ELECTRIC APPARATUS; MANUFACTURE OF ASSEMBLAGES OF ELECTRICAL COMPONENTS
    • H05K2203/00Indexing scheme relating to apparatus or processes for manufacturing printed circuits covered by H05K3/00
    • H05K2203/11Treatments characterised by their effect, e.g. heating, cooling, roughening
    • H05K2203/1157Using means for chemical reduction

Definitions

  • the present invention relates to a soldering method by reflow of electronic components on a support such as a printed circuit board, and also relates to a soldering device for the implementation of such a method.
  • soldering consists in bringing the wafers carrying the electronic components to be soldered into contact with one or more waves of liquid solder alloy obtained by circulation of a solder bath contained in a tank, by means of a nozzle.
  • the wafers are previously fluxed in an upstream zone, using a flux spray or a flow foam, then preheated so as to activate the fluxes previously deposited, in order to clean the surfaces to be brazed, to elimination of oxides, organic contaminants, etc ...
  • brazing alloy there is a quantity of brazing alloy at the connection locations of the components on the circuit, for example by screen printing a solder paste containing a mixture of metallic alloy and flux on the printed circuit before depositing the components to be soldered on.
  • brazing alloy had been the object of pre-deposit (s) on the support, on locations of connection of the components, pre-deposit (s) remelt (s) ("reflow "), this being generally followed by an operation of planarizing the surface of the previously remelted pre-deposits (formation of" bumps "in English, we will refer to the SIPAD TM processes or still commercially available OPTIPAD TM), or even by the fact that the brazing alloy has been pre-deposited for certain components on the terminations of the components themselves. It is only then that the components are positioned on the support.
  • the support provided with the components is then inserted into a reflow oven so as to provide the amount of heat necessary to allow the melting of the metal alloy, as well as the activation of the fluxing element contained in the paste or pre-deposit.
  • the object of the invention is to provide a technical answer to the problems mentioned above.
  • the components are placed on support connection locations, and
  • an actual brazing operation of the components is carried out using the said brazing alloy, by heat treatment of the support, and is characterized in that said heat treatment of the support is carried out in order to perform the brazing of the components using using the brazing alloy, by bringing the support into contact, at a pressure close to atmospheric pressure, with a treatment atmosphere comprising excited or unstable chemical species, and substantially free of electrically charged species, the atmosphere being obtained by passing an initial treatment gas through an electrical discharge, and the heat treatment of the support being obtained by means of the chemical species thus heated under the action of the discharge.
  • the process according to the invention can also include one or more of the following steps:
  • polymerizable glue is deposited on the bonding locations of the support, and the said adhesive is polymerized in order to bond the components to the support at the bonding locations ;
  • brazing alloy is available by screen printing brazing paste on the support at the connection locations of the components;
  • the brazing alloy is available by the fact that the brazing alloy had been the object on the pre-deposition support (s), on the or the connection locations of the components, pre-deposition (s) then having undergone a reflow operation, then having then advantageously undergone an operation of planarizing their surface;
  • the brazing alloy is available by the fact that the brazing alloy had been pre-deposited (s) on locations / terminations of the components themselves, pre-deposit (s) having then undergone reflow operation; before or after the step of depositing adhesive on the bonding locations of the support, or even after depositing the components on the support, a fluxing operation is carried out prior to the support by treatment of the latter, at a pressure close to atmospheric pressure, by means of a fluxing atmosphere comprising excited or unstable chemical species and substantially free of electrically charged species; -
  • the fluxing atmosphere of the support is obtained by passing an initial fluxing gas through an electric discharge, the initial fluxing gas advantageously comprising a reducing gas mixture comprising hydrogen.
  • the initial treatment gas comprises a reducing gas mixture comprising hydrogen; the treatment atmosphere is obtained at a gas outlet from an apparatus for forming excited or unstable species, into which the initial treatment gas has been transformed;
  • the fluxing atmosphere is obtained at a gas outlet from an apparatus for forming excited or unstable species, in which the initial fluxing gas has been transformed; the component placement and soldering steps are carried out on the two large faces of the support, said treatment operation being carried out by means of two apparatuses for forming excited or unstable chemical species, each arranged opposite one of the faces support; the method further comprises a step of cooling the support, after said treatment, by passing the latter through a cooling atmosphere comprising a neutral gas.
  • the invention also relates to a device for brazing by reflow of electronic components on a support, for example a printed circuit board, for implementing a method as defined above, characterized in that comprises a device for conveying the supports carrying, on at least one of their faces the components to be brazed on connection locations, locations on which a brazing alloy is available, the conveying member ensuring the transfer of the supports opposite first means allowing the polymerization of glue dots present on the bonding locations of the support, and opposite the second means comprising at least one apparatus for forming a treatment atmosphere comprising excited or unstable chemical species and being substantially devoid of electrically charged species, treatment atmosphere the temperature of which makes it usable for producing, at a pressure close to the pressure atmospheric, heat treatment of the support, for the actual soldering of the components.
  • the device advantageously comprises, interposed along the conveyor upstream of the first means or between the first means and the second means, at least one apparatus for forming a fluxing atmosphere comprising excited or unstable chemical species and being substantially devoid of electrically charged species, fluxing atmosphere usable for carrying out gas phase fluxing of the support.
  • pressure close to atmospheric pressure is understood to mean a pressure advantageously situated in the range [0.1 ⁇ 10 ⁇ Pa, 3 ⁇
  • the "support” on which the components according to the invention are soldered can be very varied in nature, depending on the different supports used in the industry, as well on the electronic components to be soldered. By way of illustration, it may be supports of the printed circuit type (whatever their surface finish or finish), or even, for example, metallized ceramic supports such as hybrid circuits, or even housing bottoms on which must be soldered. circuits in a global encapsulation process.
  • the components concerned can be extremely varied, from traditional passive or active electronic components to more complex and delicate components for handling, whether they are encapsulated or bare chips (BGA, MCM, Flip Chips, etc.).
  • the “components” according to the invention may also consist of circuits which must be soldered on another support or on a bottom of the housing before encapsulation.
  • FIG. 1 is a diagrammatic view of a brazing device for implementing the method according to the invention.
  • FIG. 1 is shown a general view of a device brazing by reflow suitable for implementing the method according to the invention.
  • This device comprises a conveyor member 10 comprising a belt 12, shown in phantom, disposed in an enclosure 14 and extending between two guide rollers, 16 and 18, at least one of which is motor.
  • a set of printed circuit boards such as 20, on at least one of the large faces of which are arranged a set of electronic components, such as 22, which should be brazed.
  • the electronic components are arranged at connection locations to which solder paste, for example an alloy of tin and lead, is applied. Furthermore, points of a polymerizable adhesive suitable for the intended use have been deposited on suitable bonding points of the board (for example on polymeric surfaces of the printed circuit board, between two connection locations), ensuring keeping the components in place during their brazing.
  • solder paste for example an alloy of tin and lead
  • the mat 12 ensures the transfer of the printed circuit boards 20 carrying the components 22 opposite a first station 24 allowing, by thermal transfer, the polymerization of the adhesive deposited (for example by radiation), then through a second station 28 for heat treatment, at the level of which the actual soldering of the components 22 is carried out.
  • the belt 12 ensures the transfer of the wafers 20, downstream from the second heat treatment station 28 to a cooling station 30 at the level of which the wafers are arranged in a nitrogen atmosphere.
  • the second heat treatment station 28 can be considered to be confused with a fluxing station 26, both constituted by a module 32 for forming a treatment and fluxing gas comprising species excited or unstable chemicals and substantially free of electrically charged species.
  • the device can comprise two modules 32 for forming excited or unstable chemical species arranged each facing one of the large faces of the plate 20.
  • module 32 The function of module 32 is to pass an initial treatment gas, advantageously comprising a reducing gas mixture, for example based on nitrogen and hydrogen, supplemented, if necessary with water vapor, through an electric discharge , inside which the initial gas is transformed, so as to generate, at the gas outlet of the module, the treatment gas which comprises the excited or unstable gaseous species and which is substantially devoid of electrically charged species (situation of post-discharge).
  • the temperature of the species leaving the discharge will generally be directly sufficient (> 190 ° C.). However, in certain particular cases (certain metallic eutectics for example), it may be envisaged to preheat the initial gas somewhat before it enters the landfill.
  • FIG. 2 There is shown in Figure 2 a sectional view of an example of module 32 capable of generating such chemical species.
  • the module 32 comprises a first tubular electrode 34, formed for example by an internal face of a metal block 36, and in which is concentrically disposed an assembly formed of a tube made of dielectric material 38, for example made of ceramic, on the internal face of which is deposited, by metallization, a second electrode 40, excessively thickened in FIG. 2, in order to improve clarity.
  • the dielectric tube 38 and the second electrode 40 define, with the first electrode 34, a tubular gas passage 42, and, internally, an internal volume 44 in which a refrigerant is circulated.
  • the block 36 comprises, diametrically opposite, two longitudinal slots 46 and 48, respectively forming the inlet of the initial treatment gas to be transformed (excited) in the passage 42 and the outlet of the treatment atmosphere stream comprising the excited gaseous species or unstable but substantially devoid of electrically charged species.
  • the slots 46 and 48 extend over the entire axial length of the cavity 42.
  • the block 36 also advantageously comprises, at the periphery of the first electrode 34, a plurality of conduits, such as 50, for the passage of a cooling fluid, for example water.
  • a cooling fluid for example water.
  • the gas inlet slot 6 communicates with a homogenization chamber 52 formed in a housing 54 attached to the block 36 and comprising a pipe 56 for supplying initial gas.
  • the module is completed by an electric generator 58 at high voltage and high frequency intended to generate a discharge in the gas mixture circulating in the gas passage 42 so as to cause, by ionization, an excitation of the gas molecules entering into its constitution and to thus generating excited or unstable chemical species, in particular H * or H 2 " radicals, which deoxidize and decontaminate the external surface of the printed circuit boards 20 (FIG. 1).
  • the method of soldering electronic components on a wafer circuit board is done here as follows.
  • wafers 20 are used on which solder paste has been screen printed, at connection locations of the components. It would also have been possible to use a brazing alloy which has been the subject of pre-deposits on the wafer on locations for connection of the components, and of a pre-reflow, in general followed by an operation of flattening of the surface. pre-deposits thus obtained (industrially available processes well known to those skilled in the art of microelectronics). It could also be components having themselves locations / terminations on which a pre-deposit of brazing alloy has been carried out.
  • the latter transfers the wafers from the loading station to the first adhesive polymerization station 24, and the circuit is thus preheated.
  • the platelets are transferred to the module 32 for the formation of excited or unstable chemical species, described previously with reference to FIG. 3, at which level the platelets, on the one hand, undergo an operation of fluxing, under the action of the chemical species delivered by the module 32 and, on the other hand and at the same time, under the action of the heat transmitted to these excited species under the effect of the discharge, the components are brazed on the brochure.
  • the process is continued here by a step of cooling the wafers, under the action of a flow of nitrogen supplied at the level of the cooling station.
  • the first step of thermal treatment of polymerization and preheating of the wafer is carried out by means of a specific station 24.
  • the actual heat treatment for reflow is carried out with active species (cleaning, deoxidation, etc.) making it possible to avoid any oxidation phenomenon and therefore to substantially improve the wetting performance;
  • the method according to the invention makes it possible to combine completely satisfactory brazing performance, while making it possible to avoid the subsequent cleaning operation of the supports.
  • the invention has been particularly exemplified in the foregoing by positioning a module for forming the treatment or fluxing atmosphere on the path of the supports (or even one module per side), it is of course possible to envisage the presence of several modules in series and / or in parallel making it possible to obtain the required effect, but one can also consider (depending on the case of each user site) the fact of not installing, facing one or each face support, that a module (whether processing or fluxing), by performing successive ironings next to the module to obtain the desired effect.

Abstract

The invention concerns a method for brazing by solder reflow electronic components (22) on a support, for example a printed circuit wafer (20) which consists in: arranging a solder alloy on the support (20) in sites for connecting the components (22); placing the components on the connection sites and brazing the components (22) properly speaking by a thermal treatment of the support, by contacting it, at a pressure close to atmospheric pressure, with a treating atmosphere comprising excited or unstable species substantially free from electrically charged species, the atmosphere being obtained by passing an initial treating gas in an electrical discharge, and the thermal treatment of the support being obtained by using the species thus heated by the action of the discharge.

Description

PROCEDE DE BRASAGE PAR REFUSION REFUSION BRAZING PROCESS
DE COMPOSANTS ELECTRONIQUES ET DISPOSITIFOF ELECTRONIC COMPONENTS AND DEVICE
DE BRASAGE POUR LA MISE EN OEUVRE D'UN TEL PROCEDEOF BRAZING FOR THE IMPLEMENTATION OF SUCH A PROCESS
La présente invention est relative à un procédé de brasage par refusion de composants électroniques sur un support tel qu'une plaquette de circuit imprimé, et se rapporte également à un dispositif de brasage pour la mise en oeuvre d'un tel procédé.The present invention relates to a soldering method by reflow of electronic components on a support such as a printed circuit board, and also relates to a soldering device for the implementation of such a method.
Les deux méthodes les plus couramment utilisées pour effectuer une opération de brasage, sont le "brasage à la vague" (wave soldering an anglais) et le "brasage par refusion" (reflow soldering en anglais) .The two most commonly used methods of performing a soldering operation are "wave soldering" and "reflow soldering".
Dans le premier cas, c'est-à-dire le brasage à la vague, le brasage consiste à amener les plaquettes portant les composants électroniques à braser en contact avec une ou plusieurs vagues d'alliage de soudure liquide obtenues par circulation d'un bain de soudure contenu dans un bac, au moyen d'une buse.In the first case, that is to say wave soldering, soldering consists in bringing the wafers carrying the electronic components to be soldered into contact with one or more waves of liquid solder alloy obtained by circulation of a solder bath contained in a tank, by means of a nozzle.
Généralement, les plaquettes sont préalablement fluxées dans une zone amont, à l'aide d'un spray de flux ou d'une mousse de flux, puis préchauffés de manière à activer les flux précédemment déposés, afin de nettoyer les surfaces à braser, pour l'élimination des oxydes, des contaminants organiques, etc...Generally, the wafers are previously fluxed in an upstream zone, using a flux spray or a flow foam, then preheated so as to activate the fluxes previously deposited, in order to clean the surfaces to be brazed, to elimination of oxides, organic contaminants, etc ...
Dans la seconde technique de brasage "par refusion", on dispose d'une quantité d'alliage de brasure en des emplacements de connexion des composants sur le circuit, par exemple en sérigraphiant une pâte à braser contenant un mélange d'alliage métallique et de flux sur le circuit imprimé avant d'y déposer les composants à braser. Une autre technologie récente consiste en ce que l'alliage de brasure avait fait l'objet de pré-dépôt (s) sur le support, sur des emplacements de connexion des composants, pré-dépôt (s) refondu(s) ("refusion"), ceci étant en général suivi d'une opération d' aplanissement de la surface des pré-dépôts précédemment refondus (formation de "bumps" en anglais, on se reportera aux procédés SIPAD™ ou encore OPTIPAD™ industriellement disponibles), voire par le fait que l'alliage de brasure à fait l'objet pour certains composants d' un pré-dépôt sur des terminaisons des composants proprement dits. Ce n'est qu'ensuite que l'on procède au positionnement des composants sur le support.In the second "reflow" brazing technique, there is a quantity of brazing alloy at the connection locations of the components on the circuit, for example by screen printing a solder paste containing a mixture of metallic alloy and flux on the printed circuit before depositing the components to be soldered on. Another recent technology consists in that the brazing alloy had been the object of pre-deposit (s) on the support, on locations of connection of the components, pre-deposit (s) remelt (s) ("reflow "), this being generally followed by an operation of planarizing the surface of the previously remelted pre-deposits (formation of" bumps "in English, we will refer to the SIPAD ™ processes or still commercially available OPTIPAD ™), or even by the fact that the brazing alloy has been pre-deposited for certain components on the terminations of the components themselves. It is only then that the components are positioned on the support.
Le support muni des composants est ensuite inséré dans un four à refusion de manière à apporter la quantité de chaleur nécessaire pour permettre d'obtenir la fusion de l'alliage métallique, ainsi que l'activation de l'élément fluxant contenu dans la pâte ou le pré-dépôt.The support provided with the components is then inserted into a reflow oven so as to provide the amount of heat necessary to allow the melting of the metal alloy, as well as the activation of the fluxing element contained in the paste or pre-deposit.
Comme dans le cas du brasage à la vague, cette technique nécessite l'utilisation de flux afin de nettoyer les surfaces à braser. L'utilisation de ces flux présente un certain nombre d'inconvénients, notamment en raison de leur coût, et des résidus qu'ils laissent sur les cartes, ce qui tend à générer des problèmes de fiabilité des cartes électroniques ainsi conçues. Il est donc nécessaire, avec ces techniques, de prévoir une étape supplémentaire de nettoyage des cartes après brasage, qui utilise le plus souvent des solvants chlorés, dont l'utilisation tend à être fortement limitée par les réglementations en vigueur. En outre, cette étape de nettoyage supplémentaire tend à augmenter de façon sensible le coût de fabrication des circuits.As in the case of wave soldering, this technique requires the use of flux in order to clean the surfaces to be brazed. The use of these flows has a certain number of drawbacks, in particular because of their cost, and of the residues that they leave on the cards, which tends to generate problems of reliability of the electronic cards thus designed. It is therefore necessary, with these techniques, to provide an additional step of cleaning the cards after soldering, which most often uses chlorinated solvents, the use of which tends to be greatly limited by the regulations in force. In addition, this additional cleaning step tends to significantly increase the cost of manufacturing the circuits.
Par ailleurs, on constate une forte tendance de l'industrie de la microélectronique à aller vers une miniaturisation et un taux d' intégration sur les circuits extrêmement élevés (nombre d'entrées/sorties des composants), avec en particulier l'apparition de nouveaux types de composants à nombre de connexions très élevé et à géométries de liaisons sur le circuit complexes, tels les composants appelés dans ce métier BGA, ou encore Flip Chip.In addition, there is a strong tendency in the microelectronics industry to go towards miniaturization and an integration rate on extremely high circuits (number of inputs / outputs of components), with in particular the appearance of new types of components with very high number of connections and complex connection geometries on the circuit, such as components called in this trade BGA, or even Flip Chip.
On sait par exemple que les composants BGA présentent des performances extrêmement attractives pour l'industrie, mais également un certain nombre d'inconvénients, liés notamment au fait que les connexions et joints de soudure ne sont pas latérales au composant mais situés sous le composant, rendant très difficiles tant le nettoyage que les réparations éventuelles.We know for example that BGA components offer extremely attractive performance for industry, but also a certain number of drawbacks, notably linked to the fact that the connections and solder joints are not lateral to the component but located under the component, making cleaning and possible repairs very difficult.
On se reportera, sur ces questions de nouveaux composants, et de nouvelles technologies de dépôt de brasure, aux différents articles de la revue "Advanced Packaging", July/August 1997.We will refer, on these questions of new components, and new brazing deposition technologies, to the various articles of the review "Advanced Packaging", July / August 1997.
Les documents EP-658391 et EP-747159 au nom de la Demanderesse avaient proposé des procédés et installations de fluxage par voie sèche, avant brasage ou étamage, à l'aide de mélanges gazeux comportant des espèces chimiques excitées ou instables et substantiellement dépourvus d'espèces électriquement chargées.Documents EP-658391 and EP-747159 in the name of the Applicant had proposed processes and installations for dry fluxing, before brazing or tinning, using gaseous mixtures comprising excited or unstable chemical species and substantially free of electrically charged cash.
Les travaux menés à bien par la Demanderesse ont montré que ces procédés devaient encore être améliorés dans le cas du brasage par refusion, non seulement pour améliorer les conditions de brasage des composants spéciaux mais également de façon générale les conditions de fluxage permettant d'éviter l'opération de nettoyage des supports en aval.The work carried out by the Applicant has shown that these processes still need to be improved in the case of reflow soldering, not only to improve the soldering conditions of the special components but also generally the fluxing conditions making it possible to avoid 'downstream support cleaning operation.
Le but de l'invention est d'apporter une réponse technique aux problèmes ci-dessus mentionnés.The object of the invention is to provide a technical answer to the problems mentioned above.
Elle a donc pour objet un procédé de brasage par refusion de composants électroniques sur un support, au cours duquel :It therefore relates to a soldering process by reflow of electronic components on a support, during which:
- on dispose d'une quantité d'alliage de brasure,- there is a quantity of brazing alloy,
- on place les composants sur des emplacements de connexion du support, etthe components are placed on support connection locations, and
- on effectue une opération de brasage proprement dite des composants à l'aide du dit alliage de brasure, par traitement thermique du support, et se caractérise en ce qu' on procède audit traitement thermique du support pour réaliser le brasage des composants à l'aide de l'alliage de brasure, par mise en contact du support, à une pression voisine de la pression atmosphérique, avec une atmosphère de traitement comportant des espèces chimiques excitées ou instables et substantiellement dépourvue d'espèces électriquement chargées, l'atmosphère étant obtenue par passage d'un gaz initial de traitement dans une décharge électrique, et le traitement thermique du support étant obtenu au moyen des espèces chimiques ainsi chauffées sous l'action de la décharge.- an actual brazing operation of the components is carried out using the said brazing alloy, by heat treatment of the support, and is characterized in that said heat treatment of the support is carried out in order to perform the brazing of the components using using the brazing alloy, by bringing the support into contact, at a pressure close to atmospheric pressure, with a treatment atmosphere comprising excited or unstable chemical species, and substantially free of electrically charged species, the atmosphere being obtained by passing an initial treatment gas through an electrical discharge, and the heat treatment of the support being obtained by means of the chemical species thus heated under the action of the discharge.
Le procédé suivant 1 ' invention peut en outre comporter une ou plusieurs des étapes suivantes :The process according to the invention can also include one or more of the following steps:
- préalablement à l'étape de dépôt des composants, on dépose de la colle polymérisable sur des emplacements de collage du support, et l'on procède à la polymérisation de ladite colle afin de coller les composants sur le support au niveau des emplacements de collage ;- prior to the component deposition step, polymerizable glue is deposited on the bonding locations of the support, and the said adhesive is polymerized in order to bond the components to the support at the bonding locations ;
- on dispose de l'alliage de brasure en procédant à une sérigraphie de pâte à braser sur le support en des emplacements de connexion des composants ;- the brazing alloy is available by screen printing brazing paste on the support at the connection locations of the components;
- on dispose de l'alliage de brasure par le fait que l'alliage de brasure avait fait l'objet sur le support de pré-dépôt (s) , sur les ou des emplacements de connexion des composants, pré-dépôt (s) ayant ensuite subi une opération de refusion , puis ayant ensuite avantageusement fait l'objet d'une opération d' aplanissement de leur surface ;- the brazing alloy is available by the fact that the brazing alloy had been the object on the pre-deposition support (s), on the or the connection locations of the components, pre-deposition (s) then having undergone a reflow operation, then having then advantageously undergone an operation of planarizing their surface;
- on dispose de l'alliage de brasure par le fait que l'alliage de brasure avait fait l'objet de pré-dépôt (s) sur des emplacements/terminaisons des composants proprement dits, pré-dépôt (s) ayant ensuite subi une opération de refusion ; préalablement ou postérieurement à l'étape de dépôt de colle sur les emplacements de collage du support, ou encore après dépôt des composants sur le support, on procède à une opération de fluxage préalable du support par traitement de ce dernier, à une pression voisine de la pression atmosphérique, au moyen d'une atmosphère de fluxage comportant des espèces chimiques excitées ou instables et substantiellement dépourvue d'espèces électriquement chargées ; - l'atmosphère de fluxage du support est obtenue par passage d'un gaz initial de fluxage dans une décharge électrique, le gaz initial de fluxage comportant avantageusement un mélange gazeux réducteur comportant de 1 ' ydrogène ;- the brazing alloy is available by the fact that the brazing alloy had been pre-deposited (s) on locations / terminations of the components themselves, pre-deposit (s) having then undergone reflow operation; before or after the step of depositing adhesive on the bonding locations of the support, or even after depositing the components on the support, a fluxing operation is carried out prior to the support by treatment of the latter, at a pressure close to atmospheric pressure, by means of a fluxing atmosphere comprising excited or unstable chemical species and substantially free of electrically charged species; - The fluxing atmosphere of the support is obtained by passing an initial fluxing gas through an electric discharge, the initial fluxing gas advantageously comprising a reducing gas mixture comprising hydrogen.
- le gaz initial de traitement comporte un mélange gazeux réducteur comportant de l'hydrogène ; l'atmosphère de traitement est obtenue à une sortie de gaz d'un appareil de formation d'espèces excitées ou instables, dans lequel a été transformé le gaz initial de traitement ;- The initial treatment gas comprises a reducing gas mixture comprising hydrogen; the treatment atmosphere is obtained at a gas outlet from an apparatus for forming excited or unstable species, into which the initial treatment gas has been transformed;
- l'atmosphère de fluxage est obtenue à une sortie de gaz d'un appareil de formation d'espèces excitées ou instables, dans lequel a été transformé le gaz initial de fluxage ; les étapes de placement des composants et de brasage sont effectuées sur les deux grandes faces du support, ladite opération de traitement étant effectuée au moyen de deux appareils de formation d'espèces chimiques excitées ou instables, disposés chacun en regard de l'une des faces du support ; le procédé comporte en outre une étape de refroidissement du support, postérieure au dit traitement, par passage de cette dernière dans une atmosphère de refroidissement comportant un gaz neutre.the fluxing atmosphere is obtained at a gas outlet from an apparatus for forming excited or unstable species, in which the initial fluxing gas has been transformed; the component placement and soldering steps are carried out on the two large faces of the support, said treatment operation being carried out by means of two apparatuses for forming excited or unstable chemical species, each arranged opposite one of the faces support; the method further comprises a step of cooling the support, after said treatment, by passing the latter through a cooling atmosphere comprising a neutral gas.
L'invention a également pour objet un dispositif de brasage par refusion de composants électroniques sur un support, par exemple une plaquette de circuit imprimé, pour la mise en oeuvre d'un procédé tel que défini ci-dessus, caractérisé en ce qu'il comporte un organe de convoyage des supports portant, sur au moins une de leur face les composants à braser sur des emplacements de connexion, emplacements sur lesquels on dispose d'un alliage de brasure, l'organe de convoyage assurant le transfert des supports en regard de premiers moyens permettant la polymérisation de points de colle présents sur des emplacements de collage du support, et en regard de seconds moyens comportant au moins un appareil de formation d'une atmosphère de traitement comportant des espèces chimiques excitées ou instables et étant substantiellement dépourvue d'espèces électriquement chargées, atmosphère de traitement dont la température la rend utilisable pour réaliser, à une pression voisine de la pression atmosphérique, un traitement thermique du support, en vue du brasage proprement dit des composants .The invention also relates to a device for brazing by reflow of electronic components on a support, for example a printed circuit board, for implementing a method as defined above, characterized in that comprises a device for conveying the supports carrying, on at least one of their faces the components to be brazed on connection locations, locations on which a brazing alloy is available, the conveying member ensuring the transfer of the supports opposite first means allowing the polymerization of glue dots present on the bonding locations of the support, and opposite the second means comprising at least one apparatus for forming a treatment atmosphere comprising excited or unstable chemical species and being substantially devoid of electrically charged species, treatment atmosphere the temperature of which makes it usable for producing, at a pressure close to the pressure atmospheric, heat treatment of the support, for the actual soldering of the components.
Le dispositif comporte avantageusement, intercalé le long du convoyeur en amont des premiers moyens ou entre les premiers moyens et les seconds moyens, au moins un appareil de formation d'une atmosphère de fluxage comportant des espèces chimiques excitées ou instables et étant substantiellement dépourvue d' espèces électriquement chargées, atmosphère de fluxage utilisable pour réaliser un fluxage en phase gazeuse du support.The device advantageously comprises, interposed along the conveyor upstream of the first means or between the first means and the second means, at least one apparatus for forming a fluxing atmosphere comprising excited or unstable chemical species and being substantially devoid of electrically charged species, fluxing atmosphere usable for carrying out gas phase fluxing of the support.
On entend par l'expression "pression voisine de la pression atmosphérique" selon l'invention, une pression se situant avantageusement dans l'intervalle [0,1 x 10^ Pa, 3 xThe expression "pressure close to atmospheric pressure" according to the invention is understood to mean a pressure advantageously situated in the range [0.1 × 10 ^ Pa, 3 ×
105 Pa].10 5 Pa].
Comme on l'aura compris à la lecture de ce qui précède, le "support" sur lequel sont brasés les composants selon l'invention peut être de nature très variée, suivant en cela les différents supports utilisés dans l'industrie, tout comme bien sur les composants électroniques à braser. A titre illustratif, il pourra s'agir de supports du type circuits imprimés (quel que soit leur état de surface ou finition) , ou encore par exemple de supports céramiques métallisés tels les circuits hybrides, voire de fonds de boîtiers sur lesquels doivent être brasés des circuits dans un procédé global d' encapsulation.As will be understood from reading the above, the "support" on which the components according to the invention are soldered can be very varied in nature, depending on the different supports used in the industry, as well on the electronic components to be soldered. By way of illustration, it may be supports of the printed circuit type (whatever their surface finish or finish), or even, for example, metallized ceramic supports such as hybrid circuits, or even housing bottoms on which must be soldered. circuits in a global encapsulation process.
De même les composants concernés pourront être extrêmement variés, depuis les composants électroniques traditionnels passifs ou actifs jusque des composants plus complexes et délicats de manipulation, qu'ils soient encapsulés ou puces nues (BGA, MCM, Flip Chips etc..) . Les "composants" selon l'invention pourront également consister en des circuits qu'il faut braser sur un autre support ou encore sur un fond de boîtier avant encapsulation.Likewise, the components concerned can be extremely varied, from traditional passive or active electronic components to more complex and delicate components for handling, whether they are encapsulated or bare chips (BGA, MCM, Flip Chips, etc.). The "components" according to the invention may also consist of circuits which must be soldered on another support or on a bottom of the housing before encapsulation.
D'autres caractéristiques et avantages ressortiront de la description suivante, donnée uniquement à titre d'exemple, et faite en référence aux dessins annexés sur lesquels : la figure 1 est une vue schématique d'un dispositif de brasage pour la mise en oeuvre du procédé selon l'invention ; etOther characteristics and advantages will emerge from the following description, given solely by way of example, and made with reference to the appended drawings in which: FIG. 1 is a diagrammatic view of a brazing device for implementing the method according to the invention; and
- la figure 2 est une vue schématique en coupe d'un exemple de module de formation d'espèces chimiques excitées ou instables entrant dans la constitution du dispositif de la figure 1. Sur la figure 1 on a représenté une vue générale d'un dispositif de brasage par refusion convenant pour la mise en oeuvre du procédé selon l'invention. Ce dispositif comporte un organe de convoyage 10 comportant un tapis 12, représenté en traits mixtes, disposé dans une enceinte 14 et s ' étendant entre deux rouleaux de guidage, 16 et 18, dont au moins l'un est moteur.- Figure 2 is a schematic sectional view of an example of a module for forming excited or unstable chemical species forming part of the device of Figure 1. In Figure 1 is shown a general view of a device brazing by reflow suitable for implementing the method according to the invention. This device comprises a conveyor member 10 comprising a belt 12, shown in phantom, disposed in an enclosure 14 and extending between two guide rollers, 16 and 18, at least one of which is motor.
Comme on le voit sur cette figure, sur le tapis 12 sont disposées ici un ensemble de plaquettes de circuit imprimé, tel que 20, sur au moins une des grandes faces desquelles sont disposés un ensemble de composants électroniques, tel que 22, qu'il convient de braser.As can be seen in this figure, on the carpet 12 are arranged here a set of printed circuit boards, such as 20, on at least one of the large faces of which are arranged a set of electronic components, such as 22, which should be brazed.
Les composants électroniques sont disposés au niveau d'emplacements de connexion sur lesquels est appliquée de la pâte à braser, par exemple un alliage d'étain et de plomb. Par ailleurs des points d'une colle polymérisable appropriée pour l'utilisation envisagée, ont été déposés sur des points de collage adéquats de la plaquette (par exemple sur des surfaces polymères de la plaquette de circuit imprimé, entre deux emplacements de connexion) , assurant le maintien des composants en place au cours de leur brasage.The electronic components are arranged at connection locations to which solder paste, for example an alloy of tin and lead, is applied. Furthermore, points of a polymerizable adhesive suitable for the intended use have been deposited on suitable bonding points of the board (for example on polymeric surfaces of the printed circuit board, between two connection locations), ensuring keeping the components in place during their brazing.
Le tapis 12 assure le transfert des plaquettes de circuit imprimé 20 portant les composants 22 en regard d'un premier poste 24 permettant par transfert thermique la polymérisation de la colle déposée (par exemple par rayonnement) , puis à travers un deuxième poste 28 de traitement thermique, au niveau duquel le brasage proprement dit des composants 22 est effectué.The mat 12 ensures the transfer of the printed circuit boards 20 carrying the components 22 opposite a first station 24 allowing, by thermal transfer, the polymerization of the adhesive deposited (for example by radiation), then through a second station 28 for heat treatment, at the level of which the actual soldering of the components 22 is carried out.
Enfin, le tapis 12 assure le transfert des plaquettes 20, en aval du deuxième poste 28 de traitement thermique vers un poste 30 de refroidissement au niveau duquel les plaquettes sont disposées dans une atmosphère azotée.Finally, the belt 12 ensures the transfer of the wafers 20, downstream from the second heat treatment station 28 to a cooling station 30 at the level of which the wafers are arranged in a nitrogen atmosphere.
Comme on le voit sur cette figure 1, le deuxième poste de traitement thermique 28, peut être considéré comme confondu avec un poste de fluxage 26, tous deux constitués par un module 32 de formation d'un gaz de traitement et de fluxage comportant des espèces chimiques excitées ou instables et substantiellement dépourvu d'espèces électriquement chargées.As can be seen in this FIG. 1, the second heat treatment station 28 can be considered to be confused with a fluxing station 26, both constituted by a module 32 for forming a treatment and fluxing gas comprising species excited or unstable chemicals and substantially free of electrically charged species.
Sur cette figure 1, on a considéré que les composants 22 sont disposés sur l'une des grandes faces de la plaquette 20, le module 32 de formation d'espèces excitées ou instables étant tourné vers cette face. Mais comme il apparaîtra clairement à l'homme du métier, dans le cas où les composants 22 sont disposés sur les deux grandes faces mutuellement opposées de chaque plaquette 20, le dispositif peut comporter deux modules 32 de formation d'espèces chimiques excitées ou instables disposés chacun en regard de l'une des grandes faces de la plaquette 20.In this FIG. 1, it has been considered that the components 22 are arranged on one of the large faces of the wafer 20, the module 32 for forming excited or unstable species being turned towards this face. But as will be clear to a person skilled in the art, in the case where the components 22 are arranged on the two large mutually opposite faces of each wafer 20, the device can comprise two modules 32 for forming excited or unstable chemical species arranged each facing one of the large faces of the plate 20.
Le module 32 a pour fonction de faire passer un gaz initial de traitement, comportant avantageusement un mélange gazeux réducteur, par exemple à base d'azote et d'hydrogène, complété, le cas échéant de vapeur d'eau, à travers une décharge électrique, à l'intérieur de laquelle le gaz initial est transformé, de manière à générer, en sortie de gaz du module, le gaz de traitement qui comporte les espèces gazeuses excitées ou instables et qui est substantiellement dépourvu d'espèces électriquement chargées (situation de post-décharge) . Comme on l'aura compris à la lecture de ce qui précède, selon les circuits à braser, et selon l'alliage de brasure considéré, la température des espèces en sortie de décharge sera en général directement suffisante (> 190°C) . Cependant dans certains cas particuliers (certains eutectiques métalliques par exemple) , on pourra envisager de préchauffer quelque peu le gaz initial avant son entrée dans la décharge.The function of module 32 is to pass an initial treatment gas, advantageously comprising a reducing gas mixture, for example based on nitrogen and hydrogen, supplemented, if necessary with water vapor, through an electric discharge , inside which the initial gas is transformed, so as to generate, at the gas outlet of the module, the treatment gas which comprises the excited or unstable gaseous species and which is substantially devoid of electrically charged species (situation of post-discharge). As will be understood from reading the above, depending on the circuits to be brazed, and according to the solder alloy considered, the temperature of the species leaving the discharge will generally be directly sufficient (> 190 ° C.). However, in certain particular cases (certain metallic eutectics for example), it may be envisaged to preheat the initial gas somewhat before it enters the landfill.
On a représenté sur la figure 2 une vue en coupe d'un exemple de module 32 capable de générer de telles espèces chimiques.There is shown in Figure 2 a sectional view of an example of module 32 capable of generating such chemical species.
On voit sur cette figure que le module 32 comprend une première électrode tubulaire 34, formée par exemple par une face interne d'un bloc métallique 36, et dans laquelle est disposé concentriquement un ensemble formé d'un tube en matériau diélectrique 38, par exemple en céramique, sur la face interne duquel est déposée, par métallisation, une deuxième électrode 40, exagérément épaissie sur la figure 2, afin d'améliorer la clarté. Le tube diélectrique 38 et la deuxième électrode 40 définissent, avec la première électrode 34, un passage tubulaire de gaz 42, et, intérieurement, un volume interne 44 dans lequel on fait circuler un fluide réfrigérant.It can be seen in this figure that the module 32 comprises a first tubular electrode 34, formed for example by an internal face of a metal block 36, and in which is concentrically disposed an assembly formed of a tube made of dielectric material 38, for example made of ceramic, on the internal face of which is deposited, by metallization, a second electrode 40, excessively thickened in FIG. 2, in order to improve clarity. The dielectric tube 38 and the second electrode 40 define, with the first electrode 34, a tubular gas passage 42, and, internally, an internal volume 44 in which a refrigerant is circulated.
Le bloc 36 comporte, diamétralement opposées, deux fentes longitudinales 46 et 48, formant respectivement l'entrée du gaz initial de traitement à transformer (exciter) dans le passage 42 et la sortie de flux d' atmosphère de traitement comportant les espèces gazeuses excitées ou instables mais substantiellement dépourvue d'espèces électriquement chargées.The block 36 comprises, diametrically opposite, two longitudinal slots 46 and 48, respectively forming the inlet of the initial treatment gas to be transformed (excited) in the passage 42 and the outlet of the treatment atmosphere stream comprising the excited gaseous species or unstable but substantially devoid of electrically charged species.
Les fentes 46 et 48 s'étendent sur toute la longueur axiale de la cavité 42.The slots 46 and 48 extend over the entire axial length of the cavity 42.
Par ailleurs, le bloc 36 comporte en outre, avantageusement, à la périphérie de la première électrode 34, une pluralité de conduits, tels que 50, pour le passage d'un fluide réfrigérant, par exemple de l'eau. On voit par ailleurs sur la figure 2 que la fente 6 d'entrée de gaz communique avec une chambre d'homogénéisation 52 formée dans un boîtier 54 accolée au bloc 36 et comportant une tubulure 56 d'amenée de gaz initial.Furthermore, the block 36 also advantageously comprises, at the periphery of the first electrode 34, a plurality of conduits, such as 50, for the passage of a cooling fluid, for example water. It can also be seen in FIG. 2 that the gas inlet slot 6 communicates with a homogenization chamber 52 formed in a housing 54 attached to the block 36 and comprising a pipe 56 for supplying initial gas.
Le module est complété par un générateur électrique 58 à haute tension et haute fréquence destiné à engendrer une décharge dans le mélange gazeux circulant dans le passage de gaz 42 de manière à provoquer, par ionisation, une excitation des molécules gazeuses entrant dans sa constitution et à générer ainsi des espèces chimiques excitées ou instables, en particulier des radicaux H* ou H2 ", qui viennent désoxyder et décontaminer la surface externe des plaquettes de circuit imprimé 20 (figure 1) . Le procédé de brasage de composants électroniques sur une plaquette de circuit imprimé s'effectue ici de la façon suivante.The module is completed by an electric generator 58 at high voltage and high frequency intended to generate a discharge in the gas mixture circulating in the gas passage 42 so as to cause, by ionization, an excitation of the gas molecules entering into its constitution and to thus generating excited or unstable chemical species, in particular H * or H 2 " radicals, which deoxidize and decontaminate the external surface of the printed circuit boards 20 (FIG. 1). The method of soldering electronic components on a wafer circuit board is done here as follows.
On considérera par la suite que l'on utilise des plaquettes 20 sur lesquelles de la pâte à braser a été sérigraphiée, en des emplacements de connexion des composants. On aurait également pu utiliser un alliage de brasure ayant fait l'objet de pré-dépôts sur la plaquette sur des emplacements de connexion des composants, et d'une pré-refusion, en général suivie d'une opération d' aplanissement de la surface des pré-dépôts ainsi obtenus (procédés industriellement disponibles bien connus de l'homme du métier de la microélectronique). Il pourrait également s'agir de composants possédant eux même des emplacements/terminaisons sur lesquels un pré-dépôt d'alliage de brasure a été effectué.It will subsequently be considered that wafers 20 are used on which solder paste has been screen printed, at connection locations of the components. It would also have been possible to use a brazing alloy which has been the subject of pre-deposits on the wafer on locations for connection of the components, and of a pre-reflow, in general followed by an operation of flattening of the surface. pre-deposits thus obtained (industrially available processes well known to those skilled in the art of microelectronics). It could also be components having themselves locations / terminations on which a pre-deposit of brazing alloy has been carried out.
On dépose selon l'invention comme décrit plus haut, sur des emplacements de collage, des points de colle de manière à assurer un maintien des composants au cours du brasage. On place ensuite les composants sur les emplacements de connexion puis l'on dispose les plaquettes ainsi préparées sur l'organe de convoyage, en particulier sur le tapis 12.Is deposited according to the invention as described above, on bonding locations, glue dots so as to ensure maintenance of the components during brazing. The components are then placed on the connection locations and then the pads are placed as prepared on the conveyor, in particular on the belt 12.
Celui-ci procède au transfert des plaquettes du poste de chargement vers le premier poste 24 de polymérisation de la colle, et le circuit est ainsi préchauffé.The latter transfers the wafers from the loading station to the first adhesive polymerization station 24, and the circuit is thus preheated.
Au cours de la phase suivante, les plaquettes sont transférées jusqu'au module 32 de formation d'espèces chimiques excitées ou instables, décrit précédemment en référence à la figure 3, au niveau duquel les plaquettes, d'une part, subissent une opération de fluxage, sous l'action des espèces chimiques délivrées par le module 32 et, d'autre part et en même temps, sous l'action de la chaleur transmise à ces espèces excitées sous l'effet de la décharge, les composants sont brasés sur la plaquette.During the following phase, the platelets are transferred to the module 32 for the formation of excited or unstable chemical species, described previously with reference to FIG. 3, at which level the platelets, on the one hand, undergo an operation of fluxing, under the action of the chemical species delivered by the module 32 and, on the other hand and at the same time, under the action of the heat transmitted to these excited species under the effect of the discharge, the components are brazed on the brochure.
Le procédé se poursuit ici par une étape de refroidissement des plaquettes, sous l'action d'un flux d'azote fourni au niveau du poste 30 de refroidissement.The process is continued here by a step of cooling the wafers, under the action of a flow of nitrogen supplied at the level of the cooling station.
Dans l'exemple de réalisation décrit en référence à la figure 1, on a considéré que la première étape de traitement thermique de polymérisation et de préchauffage de la plaquette est effectuée au moyen d'un poste 24 spécifique.In the embodiment described with reference to FIG. 1, it has been considered that the first step of thermal treatment of polymerization and preheating of the wafer is carried out by means of a specific station 24.
Il serait toutefois possible, en variante, d'effectuer ce chauffage préalable au moyen du gaz chauffé délivré en sortie d'un module 32 de production d'espèces chimiques excitées.It would however be possible, as a variant, to carry out this preliminary heating by means of the heated gas delivered at the outlet of a module 32 for producing excited chemical species.
Il serait par ailleurs possible de prévoir une étape de fluxage préalable des plaquettes 20 au moyen d'espèces chimiques excitées ou instables délivrées par un module identique au module 32, avant l'enduction des emplacements de collage au moyen de colle.It would also be possible to provide a step of prior fluxing of the wafers 20 by means of excited or unstable chemical species delivered by a module identical to module 32, before the coating of the bonding locations by means of glue.
Enfin, et selon un mode de réalisation non représenté, il serait également possible de réaliser le fluxage des supports et le traitement thermique de brasage non pas au moyen d'un seul et unique module mais au moyen de deux modules 32 distincts. On conçoit que l'invention qui vient d'être décrite, utilisant une étape de refusion/traitement thermique utilisant les espèces chimiques excitées ou instables et substantiellement dépourvue d'espèces électriquement chargées, chauffées sous l'action d'une décharge permet d'améliorer considérablement la qualité des brasures ainsi obtenues, tout en évitant un décapage ultérieur par solvant chloré :Finally, and according to an embodiment not shown, it would also be possible to carry out the fluxing of the supports and the brazing heat treatment not by means of a single module but by means of two distinct modules 32. It will be appreciated that the invention which has just been described, using a reflow / heat treatment step using excited or unstable chemical species and substantially free of electrically charged species, heated under the action of a discharge, makes it possible to improve considerably the quality of the solders thus obtained, while avoiding subsequent etching by chlorinated solvent:
- le traitement thermique proprement dit de refusion est réalisé avec des espèces actives (nettoyage, désoxydation.. ) permettant d'éviter tout phénomène d'oxydation et donc d'améliorer substantiellement les performances de mouillage ;- the actual heat treatment for reflow is carried out with active species (cleaning, deoxidation, etc.) making it possible to avoid any oxidation phenomenon and therefore to substantially improve the wetting performance;
- on conçoit d'autre part qu'en utilisation avec des pâtes à braser faiblement fluxées (faible activité/faible taux de résidus sur le support après brasage) ou mieux encore en utilisant des systèmes de pré-dépôt d' alliage de brasure sans flux sur des emplacements adéquats du support ou des terminaisons de composants, le procédé selon l'invention permet d'allier des performances de brasage tout à fait satisfaisantes, tout en permettant d'éviter l'opération de nettoyage ultérieure des supports.- it is also understood that in use with low flux solder paste (low activity / low residue rate on the support after brazing) or better still using pre-deposition systems of brazing alloy without flux at suitable locations of the support or of the component terminations, the method according to the invention makes it possible to combine completely satisfactory brazing performance, while making it possible to avoid the subsequent cleaning operation of the supports.
Quoique la présente invention ait été décrite en relation avec des modes de réalisation particuliers, elle ne s'en trouve pas limitée pour autant mais est au contraire susceptible de modifications et de variantes qui apparaîtront à 1 ' homme de 1 ' art dans le cadre des revendications ci-après.Although the present invention has been described in relation to particular embodiments, it is not limited thereby, but is on the contrary subject to modifications and variants which will appear to one skilled in the art in the context of claims below.
Ainsi, si l'invention a été tout particulièrement exemplifiée dans ce qui précède en positionnant sur le trajet des supports un module de formation de l'atmosphère de traitement ou de fluxage (voire un module par face) , on peut bien entendu envisager la présence de plusieurs modules en série et /ou en parallèle permettant d'obtenir l'effet requis, mais on peut également envisager (selon le cas de chaque site utilisateur) le fait de ne mettre en place, en regard d'une ou de chaque face du support, qu'un module (qu'il soit de traitement ou de fluxage), en effectuant des repassages successifs en regard du module pour obtenir l'effet voulu. Thus, if the invention has been particularly exemplified in the foregoing by positioning a module for forming the treatment or fluxing atmosphere on the path of the supports (or even one module per side), it is of course possible to envisage the presence of several modules in series and / or in parallel making it possible to obtain the required effect, but one can also consider (depending on the case of each user site) the fact of not installing, facing one or each face support, that a module (whether processing or fluxing), by performing successive ironings next to the module to obtain the desired effect.

Claims

REVENDICATIONS
1. Procédé de brasage par refusion de composants électroniques (22) sur un support (20), au cours duquel :1. A method of brazing by reflow of electronic components (22) on a support (20), during which:
- on dispose d'une quantité d'alliage de brasure, - on place les composants (22) sur des emplacements de connexion du support, et on effectue une opération de brasage des composants (22) à l'aide dudit alliage de brasure par traitement thermique du support (20) , caractérisé en ce que l'on procède audit traitement thermique du support pour réaliser ledit brasage des composants à l'aide dudit alliage de brasure, par mise en contact du support, à une pression voisine de la pression atmosphérique, avec une atmosphère de traitement comportant des espèces chimiques excitées ou instables et substantiellement dépourvue d'espèces électriquement chargées, l'atmosphère étant obtenue par passage d'un gaz initial de traitement dans une décharge électrique, et le traitement thermique du support étant obtenu au moyen des espèces chimiques ainsi chauffées sous l'action de la décharge.- a quantity of brazing alloy is available, - the components (22) are placed on the support connection locations, and a brazing operation of the components (22) is carried out using said brazing alloy by heat treatment of the support (20), characterized in that said heat treatment of the support is carried out to carry out said brazing of the components using said brazing alloy, by bringing the support into contact, at a pressure close to the pressure atmospheric, with a treatment atmosphere comprising excited or unstable chemical species and substantially devoid of electrically charged species, the atmosphere being obtained by passing an initial treatment gas through an electric discharge, and the heat treatment of the support being obtained by means of the chemical species thus heated under the action of the discharge.
2. Procédé selon la revendication 1, caractérisé en ce que préalablement à l'étape de dépôt des composants, on dépose de la colle polymérisable sur des emplacements de collage du support (20) et l'on procède à la polymérisation de ladite colle afin de coller les composants sur le support au niveau des emplacements de collage.2. Method according to claim 1, characterized in that prior to the component deposition step, polymerizable adhesive is deposited on the bonding locations of the support (20) and the said adhesive is polymerized so as to glue the components to the support at the gluing locations.
3. Procédé selon la revendication 1 ou 2, caractérisé en ce que l'on dispose du dit alliage de brasure par l'une ou plusieurs des méthodes suivantes : i) en procédant à une sérigraphie de pâte à braser sur le support (20) en des emplacements de connexion des composants ; j) l'alliage de brasure avait fait l'objet de pré- dépôt (s) sur le support en les ou des emplacements de connexion des composants, pré-dépôt (s) ayant ensuite subi une opération de refusion ; k) l'alliage de brasure avait fait l'objet de prédépôt (s) sur des emplacements/terminaisons des composants proprement dits, pré-dépôt (s) ayant ensuite subi une opération de refusion . 3. Method according to claim 1 or 2, characterized in that said solder alloy is available by one or more of the following methods: i) by screen printing brazing paste on the support (20) in connection locations of the components; j) the brazing alloy was pre-deposited on the support at the connection locations of the components, pre-deposit (s) then having undergone a reflow operation; k) the brazing alloy had been the subject of pre-deposit (s) on locations / terminations of the components proper, pre-deposit (s) having then undergone a reflow operation.
4. Procédé selon la revendication 3, caractérisé en ce que ledit pré-dépôt (s) avait ensuite fait l'objet d'une opération d' aplanissement de sa surface.4. Method according to claim 3, characterized in that said pre-deposit (s) was then subjected to an operation of planarizing its surface.
5. Procédé selon l'une des revendications précédentes, caractérisé en ce que, préalablement ou postérieurement à l'étape de dépôt de colle sur les emplacements de collage du support, on procède à une opération de fluxage du support (20) par traitement de ce dernier, à une pression voisine de la pression atmosphérique, au moyen d'une atmosphère de fluxage comportant des espèces chimiques excitées ou instables et substantiellement dépourvue d' espèces électriquement chargées .5. Method according to one of the preceding claims, characterized in that, before or after the step of depositing glue on the bonding locations of the support, a process of fluxing the support (20) is carried out by treatment of the latter, at a pressure close to atmospheric pressure, by means of a fluxing atmosphere comprising excited or unstable chemical species and substantially free of electrically charged species.
6. Procédé selon l'une des revendications 1 à 4, caractérisé en ce que, après l'étape de dépôt des composants sur le support, on procède à une opération de fluxage du support (20) par traitement de ce dernier, à une pression voisine de la pression atmosphérique, au moyen d'une atmosphère de fluxage comportant des espèces chimiques excitées ou instables et substantiellement dépourvue d'espèces électriquement chargées.6. Method according to one of claims 1 to 4, characterized in that, after the step of depositing the components on the support, a process of fluxing the support (20) is carried out by treatment of the latter, at a pressure close to atmospheric pressure, by means of a fluxing atmosphere comprising excited or unstable chemical species and substantially free of electrically charged species.
7. Procédé selon la revendication 5 ou 6, caractérisé en ce que l'atmosphère de fluxage est obtenue par passage d'un gaz initial de fluxage dans une décharge électrique. 7. Method according to claim 5 or 6, characterized in that the fluxing atmosphere is obtained by passing an initial fluxing gas through an electrical discharge.
8. Procédé selon la revendication 7, caractérisé en ce que le gaz initial de fluxage comporte un mélange gazeux réducteur comportant de l'hydrogène.8. Method according to claim 7, characterized in that the initial fluxing gas comprises a reducing gas mixture comprising hydrogen.
9. Procédé selon l'une quelconque des revendications précédentes, caractérisé en ce que le gaz initial de traitement comporte un mélange gazeux réducteur comportant de l'hydrogène. 9. Method according to any one of the preceding claims, characterized in that the initial treatment gas comprises a reducing gas mixture comprising hydrogen.
10. Procédé selon l'une quelconque des revendications précédentes, caractérisé en ce que l'atmosphère de traitement est obtenue à une sortie de gaz d'un appareil de formation d'espèces excitées ou instables, dans lequel a été transformé le gaz initial de traitement.10. Method according to any one of the preceding claims, characterized in that the treatment atmosphere is obtained at a gas outlet from an apparatus for forming excited or unstable species, in which the initial gas has been transformed. treatment.
11. Procédé selon l'une quelconque des revendications 5 à 8, caractérisé en ce que l'atmosphère de fluxage est obtenue à une sortie de gaz d'un appareil de formation d'espèces excitées ou instables, dans lequel a été transformé le gaz initial de fluxage.11. Method according to any one of claims 5 to 8, characterized in that the fluxing atmosphere is obtained at a gas outlet of an apparatus for forming excited or unstable species, in which the gas has been transformed initial fluxing.
12. Procédé selon la revendication 10, caractérisé en ce que les étapes de placement des composants et de brasage sont effectuées sur les deux grandes faces du support (20) , ladite opération de traitement thermique étant effectuée au moyen de deux appareils (32) de formation d'espèces chimiques excitées ou instables, disposés chacun en regard de l'une des faces du support.12. Method according to claim 10, characterized in that the steps of placing the components and soldering are carried out on the two large faces of the support (20), said heat treatment operation being carried out by means of two devices (32) of formation of excited or unstable chemical species, each arranged opposite one of the faces of the support.
13. Procédé selon l'une quelconque des revendications précédentes, caractérisé en ce qu'il comporte en outre une étape de refroidissement du support, postérieure au dit traitement thermique, par passage du support dans une atmosphère de refroidissement comportant un gaz neutre.13. Method according to any one of the preceding claims, characterized in that it further comprises a step of cooling the support, after said heat treatment, by passing the support through a cooling atmosphere comprising a neutral gas.
14. Dispositif de brasage par refusion de composants électroniques (22) sur un support (20) à l'aide d'un alliage de brasure, pour la mise en oeuvre du procédé selon l'une quelconque des revendications 1 à 13, caractérisé en ce qu'il comporte un organe (10) de convoyage de supports (20) portant, sur au moins une de leurs faces, les composants (22) à braser sur des emplacements de connexion, l'organe (10) de convoyage assurant le transfert des supports en regard de premiers moyens (24) permettant la polymérisation de points de colle présents sur des emplacements de collage du support (20) , et en regard de seconds moyens comportant au moins un appareil (28) de formation d'une atmosphère de traitement comportant des espèces chimiques excitées ou instables et étant substantiellement dépourvue d' espèces électriquement chargées, atmosphère de traitement dont la température la rend utilisable pour réaliser, à pression voisine de la pression atmosphérique, un traitement thermique du support, en vue du brasage proprement dit des composants .14. Brazing device by remelting electronic components (22) on a support (20) using a solder alloy, for implementing the method according to any one of claims 1 to 13, characterized in what it comprises a member (10) for conveying supports (20) carrying, on at least one of their faces, the components (22) to be brazed on connection locations, the member (10) for conveying ensuring transfer of the supports opposite the first means (24) allowing the polymerization of glue dots present on the bonding locations of the support (20), and opposite the second means comprising at least one device (28) for forming an atmosphere of treatment comprising excited or unstable chemical species and being substantially devoid of species electrically charged, treatment atmosphere the temperature of which makes it usable for carrying out, at pressure close to atmospheric pressure, heat treatment of the support, with a view to the actual soldering of the components.
15. Dispositif selon la revendication 14, caractérisé en ce qu'il comporte, intercalé le long de l'organe de convoyage, en amont des premiers moyens ou entre les premiers moyens et les seconds moyens, au moins un appareil (28) de formation d'une atmosphère de fluxage comportant des espèces chimiques excitées ou instables et étant substantiellement dépourvue d' espèces électriquement chargées, atmosphère de fluxage utilisable pour réaliser un fluxage en phase gazeuse du support (20) . 15. Device according to claim 14, characterized in that it comprises, interposed along the conveying member, upstream of the first means or between the first means and the second means, at least one device (28) for forming a fluxing atmosphere comprising excited or unstable chemical species and being substantially devoid of electrically charged species, fluxing atmosphere usable for carrying out fluxing in the gas phase of the support (20).
PCT/FR1999/001657 1998-07-30 1999-07-08 Method for brazing by solder reflow electronic components and brazing device therefor WO2000006333A1 (en)

Priority Applications (6)

Application Number Priority Date Filing Date Title
CA002338157A CA2338157A1 (en) 1998-07-30 1999-07-08 Method for brazing by solder reflow electronic components and brazing device therefor
JP2000562170A JP2002521207A (en) 1998-07-30 1999-07-08 Method for brazing electronic components by solder reflow and brazing device therefor
BR9912560-9A BR9912560A (en) 1998-07-30 1999-07-08 Electronic components reflow soldering process, and welding device for the application of this process
KR1020017001258A KR20010053616A (en) 1998-07-30 1999-07-08 Method for brazing by solder reflow electronic components and brazing device therefor
EP99929437A EP1100644A1 (en) 1998-07-30 1999-07-08 Method for brazing by solder reflow electronic components and brazing device therefor
AU46253/99A AU4625399A (en) 1998-07-30 1999-07-08 Method for brazing by solder reflow electronic components and brazing device therefor

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FR98/09773 1998-07-30
FR9809773A FR2781706B1 (en) 1998-07-30 1998-07-30 METHOD OF BRAZING BY REFUSION OF ELECTRONIC COMPONENTS AND BRAZING DEVICE FOR CARRYING OUT SUCH A METHOD

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EP1100644A1 (en) 2001-05-23
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TW416881B (en) 2001-01-01
BR9912560A (en) 2001-05-02
CA2338157A1 (en) 2000-02-10
KR20010053616A (en) 2001-06-25
FR2781706B1 (en) 2000-08-25
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HUP0104961A2 (en) 2002-05-29
CN1307508A (en) 2001-08-08

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