Power module and method for manufacturing a power module

Abstract

The invention relates to a power module (1) and to a method for producing a power module (1), comprising at least one printed circuit board (6) with at least one power semiconductor (7), a housing (2), an insulating filler material (5) and an insulating film (9), at least one solderable contact (10) being embedded in the insulating film (9), the contacts project laterally from the insulating film (9) and are soldered to the printed circuit board (6).

Description

Technical Field

[0001] The invention relates to a power module and a method for producing a power module. Background Art

[0002] The power module comprises at least one printed circuit board with at least one power semiconductor, a housing and an insulating filling material. The insulating filling material is also referred to as a gap filler. The gap filler is a soft, elastic, relatively thick thermally conductive pad with thermally conductive properties and compensates for height differences between the components through its material thickness and elasticity. In order to increase the dielectric strength, a combination of a gap filler and a thin insulating film is also known. Such an insulating film is known, for example, under the brand Kapton-MT film and is, for example, 25 μm thick.

[0003] The power semiconductors in such power modules generate relatively high power losses in the watt range. Another problem is that they are usually switched at high frequencies. This leads to EMC problems, so that the housing is conductive for shielding. For example, housings made of aluminum die castings are known. Since voltages in the high voltage range (e.g. 400 V) may be present on the printed circuit board, the components with voltage must have a minimum distance relative to the housing. This is specified, for example, in IEC standards. Here, the air distance is specified.

[0004] The problem with gap fillers is that, although resistance values ​​are specified for the gap fillers, no guarantees can be given for the dielectric strength, since defects and inclusions in the material cannot be excluded. This can be partially compensated, for example, by selecting the thickness of the gap filler to be thicker than that specified in the standard. In addition, the insulating films described above can be used. However, the processing of such films has proven to be difficult. For example, these films must be bonded to the gap filler and the housing by means of acrylic or polysiloxane adhesives. In terms of process technology, such bonding processes with very thin films are difficult and can only be automated with difficulty. Another problem is that the surface of the housing is rough, which further makes the bonding process difficult, so that the housing must be processed accordingly.

[0005] DE 10 2007 057 533 B4 discloses a printed circuit board with a heat sink, wherein the printed circuit board has through-holes, ie holes or metallized through-holes, from the upper side to the lower side of the printed circuit board for better thermal connection. Summary of the invention

[0006] The present invention is based on the following technical problem: to create a power module that can be manufactured in a simplified manner, and to provide a corresponding manufacturing method for use.

[0007] The solution to this problem is achieved by a power module having the features of claim 1 and a method having the features of claim 9. Further advantageous embodiments of the invention are disclosed in the dependent claims.

[0008] The power module comprises at least one printed circuit board with at least one power semiconductor, a housing, an insulating filling material and an insulating film, wherein at least one solderable contact is embedded in the insulating film, and the contact accordingly extends laterally from the insulating film and is soldered to the printed circuit board. As a result, the film no longer has to be bonded, wherein the soldering process can preferably be integrated into the remaining soldering process of the printed circuit board. Therefore, the soldering of the contacts is mainly used for mechanical connection. Another advantage is that the solderable contacts can also conduct heat away from the printed circuit board. The housing is preferably electrically conductive and further preferably consists of metal. The insulating filling material (gap filler) preferably has a thermal conductivity greater than / equal to 10. 6 Here, it should be noted that the gap filler should also include the gap spacer in concept. The insulating film preferably has a breakdown voltage greater than 5 kV.

[0009] In one embodiment, the insulating film is configured as a printed circuit board connector. Such printed circuit board connectors are actually used to connect two printed circuit boards and are suitable for SMT (surface mount technology). Currently, it is now fully utilized that these printed circuit board connectors already have an insulating layer with embedded contacts, so that they can be used as cost-effective standard components. For example, such printed circuit board connectors are provided by SUMIDA under the product name PANTA.

[0010] In a further embodiment, the power module has at least one heat sink, which improves heat dissipation.

[0011] In this case, in one embodiment, the heat sink may be arranged below the printed circuit board.

[0012] In an alternative embodiment, at least one heat sink is arranged on at least one power semiconductor. Embodiments in which both variants are combined are also possible.

[0013] In another embodiment, the printed circuit board has through holes to improve thermal bonding.

[0014] In another embodiment, the insulating film is arranged between the heat sink and the insulating filler material, wherein the insulating film completely covers the heat sink and the insulating filler material, thereby reliably avoiding voltage breakdown. Another advantage is that the insulating film is not in direct contact with the housing, so that the housing does not need to be additionally processed.

[0015] In another embodiment, the housing has a projection on the bottom or cover that projects into the interior of the housing. Thus, a defined support surface is present, wherein the spacing of the circuit board relative to the housing is additionally increased, which spacing is not covered by the insulating film.

[0016] The power semiconductors are preferably power transistors of a pulse-controlled inverter.

[0017] A method for producing a power module, wherein the power module has at least one printed circuit board with at least one power semiconductor, a housing, an insulating filling material and an insulating film, wherein at least one solderable contact is embedded in the insulating film and protrudes laterally from the insulating film, comprising the method step of soldering at least one contact to the printed circuit board.

[0018] For other design solutions, please refer to the previous implementation plans in detail. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] The present invention will be explained in more detail below based on preferred embodiments. In the accompanying drawings:

[0020] Figure 1 A partial diagram of a power module in a first embodiment is shown,

[0021] Figure 2 A partial view of a power module in a second embodiment is shown, and

[0022] Figure 3 A perspective view of a printed circuit board connector (prior art) is shown. DETAILED DESCRIPTION

[0023] exist Figure 1, a partial view of a power module 1 is shown, wherein the power module 1 has a housing 2 with a bottom 3. The side walls and the cover are not shown. In addition, the housing has a protrusion 4, which extends into the interior of the housing 2. An insulating filling material 5, a so-called gap filler or gap pad, is arranged on the protrusion 4. The insulating filling material 5 here slightly extends beyond the protrusion 4, but can also just end with the protrusion. Due to the elasticity of the insulating filling material 5, the insulating filling material compensates for possible unevenness of the protrusion 4. The thickness D of the insulating filling material 5 is slightly greater than the required air spacing according to the IEC standard. In addition, the power module 1 has a printed circuit board 6 with at least one power semiconductor 7, wherein a heat sink 8 is arranged at the bottom of the printed circuit board 6. In addition, between the heat sink 8 and the insulating filling material 5 is an insulating film 9, which has at least one embedded solderable contact 10, which contacts each extend laterally from the insulating film 9 and are soldered to the printed circuit board 6. The film 9 completely covers the heat sink 8 and the insulating filling material 5 here. Furthermore, a through-hole 11 is shown in order to better dissipate heat from the top side of the printed circuit board 6 to the bottom side.

[0024] To produce the power module 1, the printed circuit board 6 can then be connected to the power semiconductor 7, the cooling body 8 and the film 9 with the contacts 10 in a soldering process. However, the cooling body 8 can also be connected to the printed circuit board 6 by other methods (for example by means of an adhesive connection or a sintering connection). The insulating filling material 5 can then be positioned on the protrusion 5, wherein the assembly consisting of the printed circuit board 6, the power semiconductor 7, the cooling body 8 and the film 9 is then subsequently positioned on the insulating filling material 5. The connection between the film 9 and the filling material 5 can be an adhesive connection, wherein the insulating filling material can also be designed with a self-adhesive top side for this purpose.

[0025] exist Figure 2 An alternative embodiment of the power module 1 is shown in FIG. Figure 1 The same elements are provided with the same reference numerals. Figure 1 Instead, the fixing takes place at the cover 12 of the housing 2. Another difference is that the cooling body 8 is arranged on at least one power semiconductor 7. Then, the printed circuit board 6, the power semiconductor 7, the cooling body 8 and the insulating film 9 can be prefabricated into an assembly again in a soldering process, and then the assembly is placed on the insulating filling material 5, wherein the filling material 5 is previously positioned on the protrusion 4. Then, the cover 11 is subsequently placed on the remaining housing 2. The housing 2 is preferably an aluminum housing.

[0026] exist Figure 31 shows a perspective view of a printed circuit board connector 12. The printed circuit board connector has a plurality of contacts 10 embedded in an insulating layer. For example, such a printed circuit board connector 13 can be produced by means of a punched grid for the contacts 10, wherein the insulating film is respectively stretched out in the middle from above and below and compressed. Such a printed circuit board connector 13 can now be used as an insulating film 9 with embedded, solderable contacts 10 for a power module.

[0027] Reference numerals list

[0028] 1 Power Module

[0029] 2 Housing

[0030] 3 Bottom

[0031] 4 Protrusions

[0032] 5 Filling materials

[0033] 6. Printed Circuit Board

[0034] 7 Power Semiconductors

[0035] 8 cooling body

[0036] 9 films

[0037] 10 Contacts

[0038] 11 Through hole

[0039] 12. Lid

[0040] 13 PCB connector

Claims

1. A power module (1), comprising at least one printed circuit board (6) with at least one power semiconductor (7), a housing (2), an insulating filling material (5) and an insulating film (9), It is characterized in that At least one solderable contact (10) is embedded in the insulating film (9), each of which protrudes laterally from the insulating film (9) and is soldered to the printed circuit board (6).

2. The power module according to claim 1, characterized in that: The insulating film (9) is configured as a printed circuit board connector (13).

3. The power module according to claim 1 or 2, characterized in that: The power module (1) has at least one heat sink (8).

4. The power module according to claim 3, characterized in that: The cooling body (8) is arranged below the printed circuit board (6).

5. The power module according to claim 3, characterized in that: The heat sink (8) is arranged on the at least one power semiconductor (7).

6. The power module according to any one of claims 3 to 5, characterized in that: The printed circuit board (6) has a through hole (11).

7. The power module according to any one of claims 3 to 6, characterized in that: The insulating film (9) is arranged between the cooling body (8) and the insulating filling material (5), wherein the insulating film completely covers the cooling body (8) and the insulating filling material (5).

8. The power module according to any one of the preceding claims, characterized in that The housing (2) has a projection (4) on the bottom (3) or the cover (12) which projects into the interior of the housing (2).

9. A method for manufacturing a power module (1), wherein: The power module (1) comprises at least one printed circuit board (6) with at least one power semiconductor (7), a housing (2) and an insulating filling material (5). It is characterized in that At least one solderable contact (10) is embedded in the insulating film (9), each of which protrudes laterally from the insulating film (9), wherein the at least one contact (10) is soldered to the printed circuit board (6).

10. The method according to claim 9, characterized in that The insulating film (9) is designed as a printed circuit board connector (13) with a plurality of contacts (10), wherein at least a plurality of contacts (10) are soldered to the printed circuit board (6).

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