JPH0846099A - Equipment and method for uniting electric conduction and heat conduction - Google Patents

Abstract

PROBLEM TO BE SOLVED: To form an electrically and thermally conductive joint between a diode and a structural part, i.e., a sheet sink, by jointing the diode and the structural part through ultrasonic welding using the hone of an ultrasonic welder. SOLUTION: A diode 12 has a base 16 to be bonded with a diode chip 20 through a brazing filler metal 18. Contact range 32 of a hone 30 is positioned at the fringe part 34 projecting over the diode chip 20 from the base 16 thereof. The positioned hone 30 transmits a mechanical vibration in the ultrasonic frequency range generated by an ultrasonic welder to the diode 12 welded to the heat sink 14 or the base 16 thereof thus jointing the base 16 of the diode 12 and the structural part, i.e., the heat sink 14, through ultrasonic welding. Consequently, electrically and thermally conductive jointing between the diode 12 and the sheet sink 14 can be effected easily.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The invention relates to a conductive and heat-conducting connection between a diode for a three-phase alternator, in particular used in motor vehicles, in particular an output diode of a rectifier and a structural part. Apparatus and method.

[0002]

2. Description of the Prior Art It is known to use three-phase alternators for powering on-board power sources in motor vehicles (Bos).
ch Technische Unterrichtu
ng; Drehstrom-Generatoren
6/82; see pages 8 and 9). A rectifier is assigned to the three-phase alternator because the three-phase alternating current formed in the three-phase alternator must be rectified for the battery charging required in the motor vehicle.
This rectifying device has a semiconductor output diode, which is incorporated in a three-phase AC bridge circuit. In this case, since one output diode corresponds to each half-wave of each phase, in the case of full-wave rectification, a three-phase AC bridge circuit including a total of six output diodes is formed. In this case, the three positive side diodes are connected to the positive side and the three negative side diodes are connected to the negative side. As is known, the output diode is formed as a press fit diode. In this case, the output diodes of the same magnetic pole are pressed into one heat sink. The press-fitting base of the press-fitting diode is at the same time the heat conduction with good durability between the output diode and the heat sink.
It also takes on conductive coupling. Such a three-phase AC bridge circuit consisting of a press-fitting diode can only be manufactured at a relatively high cost and effort.

[0003]

SUMMARY OF THE INVENTION It is an object of the invention to improve the device for forming a conductive-heat-conducting coupling mentioned at the beginning to simplify the conductive-heat-conducting coupling between a diode and a heat sink. It is to provide a device that can be formed.

A further object of the present invention is to achieve such conductivity.
The object is to provide an advantageous method for easily forming a heat-conducting bond.

[0005]

In order to solve this problem, in the structure of the present invention, the diode is loaded by the horn of the ultrasonic welding apparatus, and the horn separates the diode from the structure. The ultrasonic welding connection between them was performed.

In order to solve the above-mentioned problems, in the method of the present invention, the conductive / heat conductive coupling is formed by ultrasonic welding between a base supporting the diode chip and a heat sink formed as a structural body part. I decided to do it.

[0007]

According to the present invention, it is possible to easily form the conductive / heat conductive coupling between the diode and the heat sink as compared with the conventional one. The diode is loaded by the horn of the ultrasonic welding device,
On the basis of the ultrasonic welding connection between the diode and the heat sink by means of this horn, the diode is subjected to an excessively large load during the formation of said connection, for example an overload which has hitherto been caused by the force input. It is very advantageous because it is possible to achieve a very tightly adhered welded joint between the diode and the heat sink without it. Due to the fact that the bond is formed by ultrasonic welding, the diode is only exposed to very small pressing forces, so that practically no deformation of the diode is possible. Thus, overall, the proportion of diodes that are no longer functional after contacting can be minimized. Furthermore, the ultrasonic welding connection between the diode and the heat sink can be carried out without special preparation of the surfaces to be contacted. This is because ultrasonic welding does not require surface cleaning and does not require the use of flux.

In an advantageous configuration of the invention, the horn of the ultrasonic welding device is designed for form-fitting engagement with the base of the diode. This is very advantageous as it allows the horn to be positioned very accurately with respect to the diode. Therefore, the formation of the ultrasonic weld bond can be integrated very well into the assembly process which is carried out in an automated manner, and in mass production the same reliable ultrasonic weld bond between the diode and the heat sink is always accurate. You will get it.

[0009]

Embodiments of the present invention will now be described in detail with reference to the drawings.

FIG. 1 illustrates an apparatus, generally designated 10, for forming a conductive and heat conductive connection between a diode 12 and a heat sink 14. The diode 12 has a base 16, which includes
A diode chip 20 is attached via the braze 18. A head plate 24 is attached to the diode chip 20 via another solder 22. This head plate 24 is only mentioned by way of example and can be used to connect a diode to a voltage source, for example the three-phase alternating current phases U, V, W formed by a three-phase alternating current generator of a motor vehicle. Appropriate alternative connection means may be provided. Both the head plate 24 and the base 16 are made of a conductive material such as copper. The heat sink 14 preferably has a circular recess 25. Inside the recess 25, a welded ridge 26 formed as a collar extends annularly. The shape of the weld ridge 26 is adapted to the base 16. That is, the base 16 rests partially, preferably annularly, on the weld ridge 26 at its surface 28 facing the heat sink 14. Due to the formation of the weld ridges 26, the surfaces of the base 16 and heat sink 14 that contact one another are reduced relative to the entire surface 28 of the base 16. The weld ridge 26 may be provided on the base 16 in another embodiment (not shown), in which case
The heat sink 14 is formed flat, that is, without the recess 25. Further, the base 16 also has a heat sink 14
However, it is also conceivable to have one weld ridge which contacts each other vertically.

Further, FIG. 1 shows a horn 30 of an ultrasonic welding apparatus (not shown in detail). The horn 30 serves to transfer mechanical vibrations generated by the ultrasonic welding device within the ultrasonic frequency range to the diode 12 or its base 16 to be welded to the heat sink 14. To this end, the horn 30 forms a contact area 32. This contact area 32 is positionable on an edge 34 projecting from the base 16 beyond the diode chip 20. To this end, the contact area 32 has an annular shoulder 3
Formed by 6. At the same time, the annular shoulder portion 36 also forms a cutout 38, and the diode chip 20 and the head plate 24 of the diode chip 20 are located inside the cutout 38. In another embodiment (not shown), the notch 38 may be connected to a passageway or the like. In that case, the cooling medium can be introduced into the notch 38 via this passage. The annular shoulder 36 forming the contact area 32 may be variously configured. In the means illustrated on the left side of FIG. 1, the annular shoulder 36 extends beyond the base 16 to form an annular step 40. The annular shoulder 36 is in shape-contact with the base 16 via the annular step 40. The end section 41 covering the base 16 has an oblique chamfer 43, which facilitates the positioning of the horn 30 on the base 16. In another embodiment shown on the right side of FIG.
An annular shoulder 36 is directly on the end surface 42 directly on the edge 34 of the base 16.
It is placed on. This end surface 42 is preferably additionally scored for the purpose of improving surface adhesion between the base 16 and the horn 30. The horn 30 may be of a mixed configuration of the illustrated annular shoulder 36 configuration.
That is, the horn 30 may alternately have, for example, a range provided with the annular shoulder portion 40 and a range provided with the end face 42 over the entire circumference thereof. Furthermore, the annular step 40 may also be provided with additional notches.

The device 10 shown in FIG. 1 for forming a conductive and heat conductive coupling between the diode 12 and the heat sink 14 performs the following functions.

The horn 30 is brought closer to the base 16 after the diode 12 is aligned with its base 16 and positioned on the weld ridge 26 of the heat sink 14. Due to the formation of the annular step 40, a very accurate positioning of the horn 30 with respect to the diode 12 is possible without great effort. In particular, this ensures that the diode chip 20 is located in the cutout 38 of the horn 30 when the horn 30 is mounted.
After the horn 30 is positioned on the base 16, the horn 30 is exposed to mechanical vibrations having a frequency in the ultrasonic range by a given device (not described in detail). By the notch provided selectively on the end surface 42,
The transmission of mechanical ultrasonic vibrations to the base 16 can be improved. Due to the ultrasonic vibration, the base 16 and the welded ridge 26 of the heat sink 14 are cold-welded at the same time as the pressing force is applied. In this case, the mass inertia of the fixed heat sink 14 is used together, which in turn creates shear stress, which causes cold welding. Due to the ultrasonic vibrations, the grid structure is exchanged between the base 16 and the heat sink 14 in a manner known per se, so that a solid welded connection results. Welding ridge 26
Based on the annular configuration of the base 16 and the heat sink 14.
The process of ultrasonic welding between and is significantly improved. Because the energy that is formed is passed through the horn 30,
This is because the reduced contact surface between the base 16 and the heat sink 14 is transmitted. In this case, the welding ridge 2
An annular weld seam extending between the heat sink 14 and the base 16 is formed corresponding to the configuration of FIG.

Since the ultrasonic welding method results in very little heating of the base 16, the diode chips 20 arranged on the base 16 are not overheated. In some cases, the diode chip 20 may be cooled by the means for supplying the cooling medium to the notch 38 as described above. Torsional vibration occurs because the horn 30 oscillates along the surface 28 of the base 16 or the horn 30 oscillates about its own longitudinal axis, depending on the configuration of the ultrasonic welding apparatus. Irrespective of the vibration mode of the horn 30, ultrasonic welding ensures a reliable and durable operation even when an unavoidable load occurs on the welded joint between the diode 12 and the heat sink 14 while the vehicle is operating. A good stable bond can easily be obtained.

Referring to FIG. 2, the use of ultrasonically welded joints is illustrated in a specific embodiment.

FIG. 2 shows the rectifying device 44 which has been assembled.
A cross-sectional view of a partial area of is shown. The basic idea of the present invention will be clarified with reference to FIG. FIG. 2 shows one negative side diode 46 and one positive side diode 48 of the three-phase AC bridge circuit. The minus diode 46 is arranged in the minus heat sink 50 so as to be thermally conductive and conductive. The plus-side diode 48 is also arranged in the plus-side heat sink 52 in a heat conductive and conductive manner. To do this, both heat sinks 5
0 and 52 have a pedestal-shaped welded ridge 26 to which diodes 48 and 46 are ultrasonically welded and contact-connected as described with reference to FIG. To expand the effective cooling surface, the heat sink 5
As shown in FIG. 2, cooling pins 5 and
May have 4.

Since the connection plate 56 is arranged between the two heat sinks 50 and 52, the sandwich structure of the rectifying device 44 as a whole, that is, the minus side heat sink 50, the connection plate 56, and the plus side heat sink 52.
A sandwich structure consisting of and is obtained. The connection plate 56 has a punched grid 58. The punched grid 58 is covered with an insulating material 60. This insulating material 60 is used for the conductive connection between the minus side heat sink 50 and the plus side heat sink 52 and for the punching grid 58.
And the conductive connection between the heat sinks 50 and 52. In the region of the negative diode 46, the connection plate 56 has a notch 62, so that a hollow chamber 64 is created at this location. Positive diode 4
In the range of 8, the connecting plate 56 has a further notch 66, so that a hollow chamber 68 is created at this location.

The punched grid 58 forms, inside the hollow chambers 64, 68, one spring 70, 72, each extending in a meandering fashion. The spring 70 has a negative diode 46.
The spring 72 is preloaded to make a contact connection with the positive diode 48. The contact connection between the springs 70; 72 and the diodes 46; 48 is the springs 70, 72.
Of the diode 4 or both springs 70, 72 are additionally provided.
6; 48, for example also by ultrasonic welding. The punched grid 58 is composed of both springs 70 and 7.
2, a conductive path is further formed. This electrically conductive path is provided with a connection terminal to which one of the phases U, V or W of the three-phase alternator can be connected.
Therefore, a part of the rectifying device shown in FIG. 2 forms a device for rectifying one of the three-phase alternating current phases of the three-phase alternator. That is, the entire rectifying device 44 has a total of three ranges shown in FIG. 2, which are formed in the same manner.

The assembling of the rectifying device 44 is performed as follows. The individual parts of the rectifying device 44 are prepared separately. That is, the minus side heat sink 50 and the plus side heat sink 52 can have desired shapes by, for example, die casting and cutting. The negative heat sink 50 is in this case advantageously also simultaneously formed as a slip ring bearing shield for the three-phase alternator. Therefore, it is possible to eliminate the additional arrangement of the negative heat sink. Further, the stamped grid 58 is stamped and shaped to the desired contour and then embedded in the insulating material by injection molding of the insulating material to form the connecting plate 56. After the production of the connecting plate 56 by injection molding, the springs 70, 72 are correspondingly plastically deformed.

In the first assembling step, the negative diode 46, which is formed as a diode chip, is its base 16 provided on the negative heat sink 50 in a conductive and conductive manner by the ultrasonic welding process described with reference to FIG. To be Similarly, the base 16 of the plus diode 48, which is also formed as a diode chip, is similarly fixed to the plus heat sink 52. Then
The pre-manufactured connection plate 56 is adjusted in position, and the minus side heat sink 5 is attached by, for example, rivets.
It is fixed at 0. Since the spring 70 is pressed against the negative diode 46 by the preload of the connection plate 56, a sufficiently large contact pressure is applied according to the set preload. In addition, the spring 70 can be welded to the negative diode 46, for example by ultrasonic waves.

In the next step, the plus side heat sink 5
2 is adjusted in position by an assembly composed of the minus side heat sink 50 and the connection plate 56, and is fixed by, for example, a screw. As a result, the positive diode 48 is located in the hollow chamber 68 and presses the preloaded spring 72, so that a sufficiently large contact pressure is generated between the positive diode 48 and the spring 72. The spring 72 also has an additional positive diode 48.
It can also be ultrasonically welded. To do this,
Assembly opening 7 provided on the minus side heat sink 50
4 helps. Through this mounting opening 74, a corresponding contact connection between the spring 72 and the positive diode 48 can be made, for example by the introduction of a correspondingly formed horn. After the contact connection is made, the mounting opening 74
Is closed airtight by a cover 76. Hollow chamber 6
4,68 can additionally be additionally filled with a sealing compound.

FIG. 3 shows a plan view of the heat sink. In this case, the heat sink may be the plus side heat sink 52 or the minus side heat sink 50. As can be seen from the drawing, the heat sink extends in an arch and is therefore adapted to the contours of the three-phase alternator. The recess 25 is visible in this plan view. A weld protrusion 26 is formed in the recess 25. The welded ridge 26 extends annularly, and in this case, the annular shape does not necessarily have to be circular. The shape of the weld ridge 26 is formed in relation to the shape of the base 16 of the diode 12 (46; 48). The weld ridge 26 may be circular, for example. In some cases, the circular weld ridge 26 has a square or rectangular base 16
May correspond to. Overall, the heat sink has weld ridges 2 for each of the rectifier phases U, V, W.
It is clear that it has at least three recesses 25 with 6. An additional recess 25 with a welding ridge 26 may be provided for the additional diode connected to the neutral point Y of the rectifier.

In summary, a rectifying device which is robust and can be manufactured easily and at low cost by means of an ultrasonic welding connection between the diode and the heat sink. Based on the extremely highly loadable ultrasonic welding connection between the diode and the heat sink or the spring and the head plate of the diode chip, the commutation is carried out over the entire expected operating time of the rectifier or the three-phase alternator with the rectifier. Chemical fatigue, mechanical fatigue and thermal fatigue in the contact area of the device can be sufficiently avoided.

[Brief description of drawings]

1 is a cross-sectional view of an apparatus for forming a conductive and heat conductive bond according to the present invention.

FIG. 2 is a sectional view showing a range of the rectifying device in a final assembled state.

FIG. 3 is a plan view of a heat sink.

[Explanation of symbols]

10 Device for forming a conductive / thermally conductive bond, 12
Diode, 14 heat sink, 16 base,
18 braze, 20 diode chip, 22 braze, 24 head plate, 26 weld ridge,
28 surface, 30 horn, 32 contact area, 34
Edge, 36 annular shoulder, 38 notch, 40 annular step, 41 end section, 42 end face, 43 diagonal chamfer, 44 rectifying device, 46 negative diode, 48 positive diode, 50 negative heat sink, 52 positive Side heat sink,
54 cooling pin, 56 connection plate, 58 punched grid, 60 insulating material, 62 notch, 64
Hollow chamber, 66 Notch, 68 Hollow chamber, 70 Spring, 72 Spring, 74 Assembly opening, 76 Cover

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Gerhard Pfruger Germany Mark Markingengen Schiller Strasse 23 (72) Inventor Arno Altopaeter Germany Sindelfingen Spitzholz Strasse 15 (72) Inventor Jörg Streller Germany Federal Republic Affalterbach Lindenstraße 66 (72) Inventor Ludwig Boltz Germany Weiblingen The Lillestraße 57 (72) Inventor Manfred Wrestler Germany Federal Republic of Stuttgart Indau Au 9 (72) Inventor Richard Spitz Germany Federal Republic of Reutlingen Leh Masteinstra 56 (72) Inventor Herbert Goebel Reutlingen Spitz Eckerweg, Germany 27 (72) Inventor Vesna Bialas Federal Republic of Germany Reutlingen Reingoldstraße 25 (72) Inventor Henning Stilke United States California Gee-Landwitt Major Shakespeare Drive 10 (72) Inventor Godehard Schmitz Germany 15 Germany (Selsheim Friedrichstrasse) 15-1 (72) Inventor Reiner Blachelt Germany Freudenthal Am Königstraße 8 (72) Inventor Thomas Richard Germany Republic Heilbronn Helbert Hoover Strasse 13 (72) Inventor Siegfried Schuler Germany Engstingen Martin Yutorase 17 (72) inventor Holger Hausmann Federal Republic of Germany Metzingen rate mer Strasse 11-1

Claims (16)

[Claims] 1. A device for forming a conductive and heat conducting connection between a diode and a structural part, wherein the diode (12) is loaded by a horn (30) of an ultrasonic welding device, Device for forming an electrically conductive and thermally conductive bond, characterized in that the horn (30) provides an ultrasonic weld bond between the diode (12) and the structural part. 2. A device according to claim 1, wherein the structural part is a heat sink (14) of a rectifying device. 3. A diode (12) is formed as a diode chip (20), said diode chip (20) comprising a base (1) made of an electrically conductive and thermally conductive material.
6) The device according to claim 1 or 2, which is arranged above. 4. The base (16) has an annular edge (34) extending around the diode chip (20).
A device according to any one of claims 1 to 3, forming a. 5. The contact area (32) of the horn (30).
And the contact area (32) has the base (1
Device according to any one of the preceding claims, which is positionable on the edge (34) of 6). 6. The contact area (32) is formed by an annular shoulder (36) of the horn (30) adapted to the shape of the base (16), the annular shoulder (36). The device according to any one of claims 1 to 5, wherein the device annularly surrounds the diode chip (20). 7. The notch (38) in the annular shoulder (36).
A device according to any one of the preceding claims, wherein the device forms a groove and a diode chip (20) is located inside the notch (38) during the ultrasonic welding process. 8. A device according to claim 1, wherein a cooling medium can be supplied to the cutout (38). 9. The annular shoulder (36) has an annular step (40) for form-formally engaging the horn (30) with the edge (34) of the base (16). 9. A device according to any one of claims 1 to 8, which is 10. The annular shoulder (36) has a score on the end surface (42) facing the base (16),
Device according to any one of claims 1-9. 11. A device according to any one of claims 1 to 10, wherein the annular shoulder (36) comprises the annular step (40) and the notch (42). 12. An ultrasonic welding connection between the diode (12) and the heat sink (14) comprises a weld ridge (2).
Device according to any one of claims 1 to 11, which is carried out via 6). 13. A device according to claim 1, wherein the weld ridges (26) are arranged on the heat sink (14) and / or the base (16). 14. The weld ridge (26) is formed by an annular collar arranged in a recess (25) provided in the heat sink (14). The described device. 15. A method for forming a conductive / thermally conductive bond between a diode and a structure part using the device according to claim 1, wherein the conductive / thermally conductive bond is formed. Is formed by ultrasonic welding between a base (16) supporting a diode chip (20) and a heat sink (14) formed as a structural part, forming a conductive / thermal conductive bond. Way to do. 16. In a rectifying device having a conductive and heat-conducting coupling between each one diode and a structural part formed as a heat sink, a diode (12), each base supporting a diode chip (20). (1
A rectifying device according to claim 6), which is fixed to the heat sink (14) by ultrasonic welding using the method according to claim 15.