US 3874075 A
A method for producing an inductive component element in which a magnetic core is covered at least partially with a non-magnetic, metallic layer which is thereafter impacted with a laser beam to partially sever selected portions of the metallic layer from other portions thereof to the finally generally helically shaped inductive coil, a layer of insulating material being interposed between the metallic layer and the magnetic core if the latter is constructed of a magnetic material having insufficient insulating properties.
Description (OCR text may contain errors)
United States Patent 11 1 1111 3,874,075 Lohse Apr. 1, 1975 METHOD FOR THE PRODUCTION OF AN 3,123,787 3/1964 Shifrin 29/602 x INDUCTIVE COMPONENT ELEMENT 3,293,587 12/1966 Robinson 219/121 L 3,319,207 5/1967 Davis 336/229 Inventor: Hartwlg L9hse, Regensburg, 3,530,573 9/1970 Helgeland 219/121 LM Germany 3,534,472 10/1970 De Jong eta] 219/121 LM  Assignee: Siemens Aktiengesellschaft, Berlin and Munich, Germany Primary Examiner-Carl E. Hall Attorney, Agent, or Firm-Hill, Gross, Simpson, Van  1973 Santen, Steadman, Chiara & Simpson  Appl. No.: 410,237
 Foreign Application Priority Data  ABSTRACT Oct. 31, 1972 Germany 2253412 A method for producing an inductive component element in which a magnetic core is covered at least par-  US. Cl 29/602, 29/625, 117/212, tially with a non-magnetic, metallic layer which is 117/234, 219/121 LM, 336/200, 336/229 thereafter impacted with a laser beam to partially  Int. Cl. H0lf 7/06 sever selected portions of the metallic layer from  Field of Search 29/602, 625, 605; 336/200, other portions thereof to the finally generally helically 336/221, 223, 233, 229; 219/121 L, 121 LM; shaped inductive coil, a layer of insulating material 117/45, 212, 234 being interposed between the metallic layer and the magnetic core if the latter is constructed of a magnetic  References Cited material having insufficient insulating properties. UNITED STATES PATENTS 6 Cl 2 D 1,994,767 3/1935 Heintz 29/602 x rawmg 'gures EATENTED APR 1 I975 SHEET 2 OF 2 METHOD FOR THE PRODUCTION OF AN INDUCTIVE COMPONENT ELEMENT- BACKGROUND OF THE INVENTION The invention is directed to a method of producing an inductive component element, particularly a miniature coil, electrical choke, or transformer.
With the continual demands for reduction in size of electronic components, and miniaturization of equipment, at strong need arises for the production of extremely small inductive elements. It will be apparent that with the greater and greater reduction in size of such components physical winding of such components becomes wholly impractical and the present invention is therefore directed to the problem of achieving a method by means of which inductive component elements of even extremely small dimensions can be produced with relatively simple procedures without the necessity of effecting one or more physical windings on a ring core or similar structure.
SUMMARY OF THE INVENTION The present invention achieves the desired results by the utilization of a magnetic core of suitable size and shape, at least partially covered with a non-magnetic metallic layer, which, for example, may be readily formed by chemical precipitation, vapor deposition or similar method, with such metallic layer being impacted by a laser beam to partially sever selected portions of the layer from other portions thereof and thereby define a generally helically shaped inductive coil.
If the magnetic material employed for the core structure possess adequate insulating characteristics, the metallic layer may be directly applied to such core structure. However, if the insulating characteristics of a magnetic material employed are unsuitable for direct application of the metallic layer thereto, the core structure may be provided with a suitable layer of organic or inorganic insulating material upon which the metallic layer is subsequently applied.
If desired, in the production of transformers, following the formation of a first coil or winding by means of a metallic layer, such coil may have super-imposed thereon an insulating layer upon which a subsequent metallic layer is applied and by means of a laser beam partially divided or severed into one or more additional coils or windings. A suitable magnetic core for this purpose may, for example, be in the form of a magnetic ring core, advantageously of rectangular configuration which is covered with a non-magnetic metallic layer and is severed into a coil or winding by means of laser beam incident at an inclination, i.e., an angle less than 90.
The mctallically covered ring core, comprising longitudinally and transversely extending connecting side portions or sections, can, for example, be impacted by a laser beam, while relative advancing movement is effected therebetween in the direction of the longitudinal portions (y-direction) by an amount equal to a single spiral pitch and can be advanced in a direction of its transverse portions (,\'-direction) by an amount which is somewhat greater than the width of the longitudinal portions, following which the ring core may be rotated through 180, and the advancing operations repeated, whereby the metallic layer is severed or divided into a helical or coil formation.
Advantageously, the laser beam may impact upon the metallic layer at an angle of about 45 with respect to the .ry-plane and at an angle with respect to the .r and y axes in dependence upon-the ring core thickness and the desired spiral pitch.
The method of the invention is also suitable for the simultaneous production of a plurality of ring cores, each of which is provided with a helically shaped metallic layer and by means of the method a miniature inductance of extremely small dimensions can be produced, which can be processed either in the form of chips, or, by means of stacking, formed into an assembly of cores to form a unit with relatively high inductivity. Advanta geously, the beginning and end portions of the helical winding of the ring core may be so positioned that a desired series connection of the individual inductances will automatically occur as a result of such stacking or arranging in layers of the individual inductive components.
The invention is also applicable to the production of inductances employing rod-shaped magnetic cores which can be rotationally symmetrical or nonsymmetrical, and which can be covered with a nonmagnetic layer and severed or divided into helicalshaped coil by the impact of the laser beam which may be incident at an inclination. The magnetic core and the laser beam may be advantageously rotated relatively to one another and longitudinal advancement effected in longitudinal direction of the core, to provide a coil of desired configuration.
In the event the coils or windings of either the rodshaped magnetic cores or the ring cores are to be traversed by greater eurrent intensities, for example, during interference elimination, the metallic layer applied upon the core can be built-up or reinforced galvanically, i.e., by an electro-plating operation which can take place either prior to or subsequent to the severance or division of the metallic layer into a helically shaped coil. Any necessary balancing or adjustment of the inductance or a component so formed may be readily achieved by the use of generally known soldered areas or sections, by means of which one or more turns of a coil may be short-circuited or left free of solder until the desired inductivity is achieved. Likewise, assemblies of several rectangularly shaped flat ring cores may be suitably balanced as to inductivity by means of short-circuiting of desired turns by a suitable contact piece or member disposed, for example, in the rectangular opening or perforation of the ring core.
A balancing or desire shifting of the inductivity of the magnetic flow in the ring core can also be achieved by the formation of a groove or a notch in a section or portion of a core which does not carry a winding. In this case, it is unimportant whether the groove is created by means of a laser beam, electronic beam, sandblasting, grinding or other suitable method. The groove can extend on one side or on several sides and can reach a defined depth which may even lead to a complete separation thereat.
BRIEF DESCRIPTION OF THE DRAWINGS In the drawings, wherein like reference characters indicate like or corresponding parts:
FIG. 1 is a simplified perspective view of an inductive component element constructed in accordance with the present invention, and illustrating in simplified schematic manner the method of production; and
FIG. 2 is a similar figure illustrating in schematic form the manner in which the method of the invention is applicable to mass production.
DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS Referring to FIG. 1, there is illustrated a small rectangular plate-like magnetic ring core 1 which is covered with a metallic layer 2 and includes contact areas 3 and 4. The core 1 is suitably advanced by a reciprocating movement in the direction of the arrow B in Y direction by an amount corresponding to the desired spiral pitch, and is suitably advanced by reciprocation in the direction of arrow A, i.e., X direction, by an amount which is somewhat greater than the width of the longitudinal sections or longer leg portions of the ring core. The metallic layer 2 is suitably severed or divided into winding turns 5 under the action of a sharply focused beam 7 of a laser device 8, only schematically represented in these FIGS. The laser beam 7 is preferably inclined to the XY plane at an angle of 45 with the component of the laser beam 7 projected on the XY plane being inclined to the X or Y axes respectively at an angle which is determined by the thickness of the ring core 1 and the desired spiral pitch. After completion of the separating operation of the lateral areas of the metallic layer 2, as illustrated in FIG. 1, the ring core may be rotated 180 and the advancing and severing operations repeated. As illustrated in FIG. 1, one or more winding turns of the coil can be short-circuited by a soldered section or area 6, illustrated as disposed on an edge portion of the core, to enable balance or adjustment of the inductivity. Such balancing or adjustment may also be achieved by the utilization of a suitable contact piece or member which bridges portions one or more winding turns of the coil.
As illustrated in FIG. 2, the invention is applicable to the mass production of inductances. In this case a plurality of ring cores may be fabricated as an integral structure with adjacent cores being separated from one another by respective grooves or notches 10 at which the cores may be broken or separated from one another. The severing or division of the respective metalized areas into respective winding turns 5 may be performed for one side of all of the cores, in a manner previously described, following which the connected cores may be rotated and the operations performed on the opposite sides thereof in the manner previously described. Likewise, the openings or perforations 11 can also be constructed as so-called breaking slots or the like.
It will be appreciated that by the use of the present method, employing a sharply defined laser beam, extremely fine coils or windings can be produced whereby the resulting inductance may have exceedingly small dimensions, and by the use of a stacking operation coils of greater inductivity may be produced.
Having thus described my invention it is obvious that although minor modifications might be suggested by those skilled in the art, it should be understood that I wish to embody within the scope of the patent warranted hereon all such modifications as reasonably come within the scope of my contribution to the art.
I claim as my invention:
1. A method for the production of an inductive component element, comprising the steps of applying a non-magnetic layer to and at least partially covering a magnetic core of rectangular, ring-shaped configuration having generally oppositely disposed faces connected by respective edge portions, and impacting the layer with a laser beam, incident at an angle of less than to partially sever selected portions of the layer from other portions thereof on both the faces and adjoining edge portions, and thereby define a generally helically shaped inductive coil.
2.. A method according to claim 1, comprising the further step of applying an insulating intermediate layer directly upon the magnetic core prior to the application of said metallic layer.
3. A method according to claim 1, wherein a selected base and edge portions are initially impacted, the core rotated through about an axis operative to correspondingly dispose the other face of the core and corresponding edge portions for beam impact, and thereafter impacting the last-mentioned face and edge portions with said laser beam.
4. A method for the production of an inductive component element, comprising the steps of applying a non-magnetic metallic layer to and at least partially covering a magnetic core of ring-like configuration, comprising a pair of spaced longitudinally extending side portions connected at their ends by respective transversely extending side portions, impacting the layer with a laser beam to partially sever selected portions of the layer from other portions thereof, while advancing the core in the direction of the longitudinal side portions (Y-direction) by an amount to provide a desired spiral pitch, and reciprocating back and forth in the direction of its transverse side portions (X- direction) by an amount which is greater than the width of the longitudinal side portions, subsequently rotating the ring core 180 about an axis in the X-Y plane, and repeating such advancing and reciprocating steps while impacting the core, whereby the metallic layer is divided into a generally helically shaped inductive coil by the action of said laser beam.
5. A method according to claim 4, comprising impacting the metallic layer with such laser beam at an angle of approximately 45 with respect to the XY- plane and at an angle with respect to the X- or Y-axis, respectively, at an angle determined by the ring core thickness and the desired spiral pitch.
6. A method according to claim 5, comprising the further step of applying an insulating intermediate layer directly upon the magnetic core piror to the application of said metallic layer.
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