Power module filled with gel material and having circuit carrier

Abstract

The invention relates to a power module having a circuit carrier, which comprises a carrier substrate and an electrically insulating layer, said circuit carrier having a first conductor structure with an outer contact region and at least one second conductor structure with at least one outer contact region, and having a further third conductor structure comprising at least one outer contact area; the invention relates to a power module having semiconductor elements arranged individually or in groups, which power module is associated with a multifunctional frame and a frame, the groups of semiconductor elements being arranged in a first plane which is spatially separated from a second plane in the multifunctional frame, the semiconductor elements are electrically connected to one another by means of a first sintered connection, which introduces at least one first spacer, or by means of a bonding connection, which introduces at least one bonding wire, and the second plane is at least partially surrounded laterally by the frame and is filled with a gel material.

Description

Technical Field

[0001] The present invention relates to a power module having a circuit carrier comprising a carrier substrate and an electrically insulating layer. The circuit carrier has a first conductor structure with an external contact region, at least one second conductor structure with at least one external contact region, and a further third conductor structure including at least one external contact region. Background Art

[0002] In the prior art, power modules, for example, mounted in a power module bridge, are additionally molded and encapsulated. During the molding process, the power modules are embedded in a robust protective housing, for example, made of plastic (molding material). The molding material serves to encase and protect the interior of the power module. However, this encapsulation of the power module with the molding material is not particularly resistant to cracking.

[0003] DE 11 2017 004 390 T5 discloses a power module having the following features: an insulating substrate with a front side, to which a power semiconductor element is attached; a base plate, which is connected to the back side of the insulating substrate; a housing, which is attached to the base plate and surrounds the insulating substrate; a cover, which is attached to the housing and forms a sealing area; and a silicone gel, which serves as a filling element, fills the entire sealing area and has an internal stress that acts as a compressive stress.

[0004] DE 10 2014 219 998 B4 discloses a power module, in particular for providing phase current for an electric motor. The power module includes a circuit carrier having a surface, at least two first contact surfaces on the surface, and at least two first power transistors, each of which has a ground contact surface. Each of the at least two first power transistors is directly arranged on a first contact surface of the first contact surfaces and is directly and electrically conductively connected to the corresponding first contact surface via its ground contact surface. The power module also includes a second contact surface on the surface and at least two second power transistors, each of which has a ground contact surface. The at least two second power transistors are directly arranged on the second contact surface and are directly and electrically conductively connected to the second contact surface via their respective ground contact surfaces. The power module also includes at least two third contact surfaces on the surface, wherein the at least two second power transistors each have a further contact surface on a side facing away from the surface of the circuit carrier, and each of the at least two second power transistors is electrically conductively connected to a respective one of the at least two third contact surfaces via its further contact surface. The at least two first contact surfaces and the at least two third contact surfaces are arranged alternately in a row along the length of the power module, and the second contact surface is arranged adjacent to the at least two first contact surfaces and the at least two third contact surfaces. The second contact surface has at least two contact regions, wherein each of the at least two contact regions is located adjacent to a respective first power transistor of the at least two first power transistors. The at least two first power transistors each have an additional contact surface on a side facing away from the circuit carrier surface, and each of the at least two first power transistors is electrically conductively connected to a contact region of the at least two contact regions located adjacent to it via its additional contact surface. The at least two contact regions of the second contact surface and the at least two second power transistors are arranged alternately in a row along the length.

[0005] EP 2 418 925 B1 discloses an electrical connection between a flexible foil having at least one conductor and at least one electrical contact of a sensor or controller. In this case, the end region of the flexible foil is contacted at a contact point via a heat-input electrical contact, wherein the end region of the flexible foil abuts against a preformed electrical contact at the contact point. The end region of the flexible foil is embodied in a corrugated, in particular, bent, manner. Summary of the Invention

[0006] According to the present invention, a power module is proposed having a circuit carrier, which includes a carrier substrate and an electrically insulating layer, wherein the circuit carrier has a first conductor structure with an external contact area, at least one second conductor structure with at least one external contact area, and a further third conductor structure with at least one external contact area; the power module also includes semiconductor elements arranged individually or in groups, so that the power module is equipped with a multifunctional frame and a frame, wherein the semiconductor element group is arranged in a first plane, which is spatially separated from a second plane in the multifunctional frame, wherein the semiconductor elements are electrically connected to each other by sintered connections introduced into at least one first spacer or by bonding connections introduced into at least one bonding wire, wherein the second plane is at least partially surrounded by the frame from the side and filled with a gel material.

[0007] The solution according to the invention achieves a particularly advantageous design by filling the power modules with a gel material. In this case, the power module or modules are typically not encased in a molding material, but are fixed to the cooling surface without molding material, wherein a frame is fixed to the cooling surface around the power modules, wherein the volume enclosed by the frame is filled with gel material so that the power module or modules are covered with gel. Silicone gel is a semi-solid substance that contains a network of silicone polymers suspended in a liquid or viscous medium. Silicone gel is heat-resistant and does not change its structure. Compared to potting materials (e.g. casting materials), gel has high elasticity and flexibility and is therefore able to absorb and distribute thermal stresses without cracking or breaking. In addition, silicone gel has a lower thermal conductivity, which improves the insulation and can better limit local temperature differences.

[0008] In another advantageous embodiment of the power module proposed according to the invention, the semiconductor elements are arranged individually or in groups on the base of the power module.

[0009] In the power module proposed according to the present invention, spacers are arranged in the joining area between the lower side of the multifunctional frame and the upper side of the power module. By arranging at least one spacer in at least one sintered connection, component tolerances and / or manufacturing tolerances generated when joining related components can be compensated. By installing spacers in the power module, short circuits can also be avoided. In addition, the installation of the spacers provides optimized heat conduction, which leads to improved performance and reliability of the power module. In addition, the spacers are coupled to the semiconductor switches and the printed circuit board, for example, via the sintered connection. The advantage of the sintered connection is, for example, that additional connecting elements such as screws, adhesives or welds are eliminated, thereby eliminating weak points or sources of failure caused by the use of these connecting elements. In addition, the sintered connection achieves a uniform stress distribution on the components of the power module because the stress is evenly distributed over the entire joining surface. Therefore, stress concentration can be reduced and the overall stability of the connection can be improved.

[0010] In another advantageous embodiment of the power module proposed according to the invention, the spacer is arranged in the joining region between the bottom side of the multifunctional frame and the top side of the power module.

[0011] In a further advantageous embodiment of the power module proposed according to the invention, the sintered connection comprises a first sintered layer, a second sintered layer and a third sintered layer.

[0012] In another advantageous embodiment of the power module according to the invention, the first sintered connection can be replaced by a first welded connection or a first soldered connection, wherein in both cases a structural unit is formed having the first, second and third layers.

[0013] In a further advantageous embodiment of the power module proposed according to the invention, the power module has a second sintered connection.

[0014] In a further advantageous embodiment of the power module proposed according to the invention, the second sintered connection comprises a fourth sintered layer and a fifth sintered layer.

[0015] In a further advantageous embodiment of the power module according to the invention, the second sintered connection can be replaced by a second welded connection or a second soldered connection, wherein in both cases a structural unit is formed having the first layer and the second layer.

[0016] In a further advantageous embodiment of the power module proposed according to the invention, the power module is connected to the cooling surface via a third soldered connection, an adhesive connection or a third sintered connection.

[0017] In another advantageous embodiment of the power module according to the present invention, the multifunctional frame is arranged above or below the power module as viewed in the Z direction.

[0018] In another advantageous embodiment of the power module proposed according to the invention, the electrically conductive components, in particular T+ bridges and T- bridges, are arranged one above the other or next to one another in the multifunctional frame, thereby forming a low-inductance connection.

[0019] In the power module according to the present invention, the multifunctional frame and the power module are separated from each other and electrically connected in the Z direction by a material-locked connection that is preferably configured as a solder connection and a weld connection. The conductive contact surface preferably extends in a multifunctional frame that can be placed above or below the power module, and the semiconductor elements arranged individually or in groups on the lower side of the power module are placed therein. The cooling surface is placed in such a way that the areas with the highest heat loss, in particular the lower side of the power module, obtain the necessary cooling. This ensures that the cooling surface remains thermally connected throughout the entire process. In addition, the solder connection enables effective unevenness compensation to compensate for any unevenness and / or irregularities that may exist between the surface of the power module and the cooling surface, thereby achieving an improved contact surface and thus optimizing heat transfer. In addition, compared to some other connection materials, the solder connection has a lower electrical conductivity, which advantageously avoids short circuits in electrically insulating connections.

[0020] The introduction of the spacers advantageously ensures effective alignment and placement of the power module components while optimizing heat conduction. The power module according to the present invention is characterized by optimized structural strength between the power module components and the multifunctional frame achieved through the sintered connections of the spacers, effectively damping vibrations, shocks, and / or other mechanical loads. Furthermore, the sintered connections enable precise shaping of the connections, ensuring correct alignment and positioning, thereby compensating for component or manufacturing tolerances.

[0021] According to the present invention, the power module is advantageously connected to the multifunctional frame via a bonded connection, a first welded connection, a first sintered connection or a first soldered connection. Here, an effective connection is achieved by means of the soldered connection, the bonded connection and the soldered connection, so that, for example, surface irregularities of the power module and / or the multifunctional frame can be compensated for by these connection methods. In addition, a mechanically strong connection can be ensured by means of the soldered connection and the soldered connection. In addition, thermal expansion differences between the power module and the multifunctional frame can be compensated by means of the soldered connection, thereby effectively avoiding stresses and cracks that may occur due to temperature fluctuations. The alternative bonded connection minimizes adverse effects such as inductance and capacitance, thereby ensuring optimized signal integrity and performance. The bonded connection also has good mechanical stability, wherein vibrations, shock loads and other mechanical stresses are effectively compensated.

[0022] Thanks to the advantageously low-inductance conduction path, a significant reduction in switching losses can be achieved. Furthermore, the low-inductance path helps minimize voltage spikes to protect the integrity of semiconductor elements and other electronic components, especially in power modules with fast switching processes. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] The embodiments of the present invention will be further described in detail by the accompanying drawings and the following description.

[0024] Figure 1 A plan view of a first circuit carrier of a power module, the circuit carrier consisting of an assembly of a carrier substrate and semiconductor elements;

[0025] Figure 2 A top view of a power module with separate cooling and layout surfaces, with areas for press-in pins provided on the side.

[0026] Figure 3 Exploded view of the arrangement of the power module, multifunctional frame, gel material, and cooling surface;

[0027] Figure 4 an enlarged view of the first sintered connection;

[0028] Figure 5 an enlarged view of the second sintered connection;

[0029] Figure 6 Magnified view of the bonded connection. DETAILED DESCRIPTION

[0030] In the following description of the embodiments of the present invention, identical or similar elements are denoted by identical reference numerals, and repeated description of these elements will be omitted in individual cases. The accompanying drawings merely schematically illustrate the subject matter of the present invention.

[0031] Figure 1 A plan view of a power module 12 is shown, in particular of its circuit carrier 14 .

[0032] From the basis Figure 1As can be seen from the top view, the carrier substrate 40 of the circuit carrier 14 is provided with a plurality of conductor structures 18, 20A, 20B, 22. The circuit carrier 14 extends in the X, Y plane 10, wherein the circuit carrier 14 is formed with an electrically insulating layer 16. On this electrically insulating layer, first conductor structures 18 are arranged, separated from one another by slot-shaped interruptions, and each has an external contact region 18.2. Furthermore, on the circuit carrier 14, second conductor structures 20A, 20B are located symmetrically relative to one another with respect to the longitudinal center axis 24 of the power module 12. Each of the two second conductor structures 20A, 20B includes an external contact region 20A.2, 20B.2. Finally, a third conductor structure 22 is applied to the circuit carrier 14, or to its electrically insulating layer 16, and has at least one external contact region 22.2.

[0033] The conductor structures 18, 20A, 20B, 22 mentioned are electrically isolated from one another and are applied to the circuit carrier 14 substantially symmetrically about the longitudinal center axis 24. AMB (active metal brazing, (oxygen-free copper / Si3N4 / oxygen-free copper)) is advantageously selected as the carrier substrate 40 of the circuit carrier 14.

[0034] according to Figure 2 The diagram of FIG shows a top view of the power module 12. In this schematic diagram, semiconductor elements 42 are arranged on the active surface 36. The semiconductor elements can be, for example, transistors, MOSFETs, IGBTs, diodes or other semiconductor elements that can be used as semiconductor switches. Figure 2 As can be seen in the figure, a first group 64 of semiconductor elements 42 is accommodated on the active surface 36. The individual semiconductor elements 42 can be constructed as MOSFETs, for example, and have control terminals 34 on their outer sides, via which the individual semiconductor elements 42 of the first group 64 of semiconductor elements 42 can be controlled, not shown in detail. Similar to the first group 64, a second group 66 of semiconductor elements 42 is arranged, which can also be MOSFETs, each of which has a control terminal 34 in its outer region. The arrangement of the semiconductor elements 42 in groups 64, 66 is not necessary and, depending on the size, the semiconductor elements can also be arranged individually, i.e. not in groups 64, 66. The semiconductor elements 42 of the second group 66 of semiconductor elements 42 can be controlled from the outside via the control terminals 34, but this is not necessary in the figure. Figure 2 Not shown in detail in the diagram.

[0035] In addition, according to Figure 2 From the top view, it can be seen that Figure 2 In the X, Y plane 10 shown, regions are arranged at the long sides of the circuit carrier 14 in the form of a carrier substrate 40, in which the press-in pins 76-94 project to the longitudinal edges according to the embodiment of the present invention. Figure 2 . Specifically, there are first and second press-in pins 76, 78, as well as third and fourth press-in pins 80, 82, and fifth and sixth press-in pins 84, 86 arranged opposite one another. Seventh and eighth press-in pins 88, 90 as well as ninth and tenth press-in pins 92, 94 are arranged in the region of the opposite end faces of the circuit carrier 14.

[0036] Figure 3 The arrangement of the power module 12, the multifunctional frame 50, the gel material 112 and the cooling surface 106 with the frame 56 is shown, wherein the frame 56 is made of plastic, for example. Figure 3 5 shows three power modules 12 positioned within a frame 56 , wherein a multifunctional frame 50 is assigned to each power module 12 . Figure 3 Also shown is an area 113 to be filled with gel material 112. Area 113 to be filled with gel material is located within the volume enclosed by frame 56. The enclosed volume can be influenced, for example, by correspondingly dimensioning frame 56. This can be done, for example, by determining the length, width, and depth dimensions of power module 12 to be implemented within frame 56.

[0037] Figure 4 An enlarged view of the first sintered connection 130 is shown. Figure 4 The first sintered connection 130 shown in FIG has a first sintered layer 122, via which the semiconductor element 42 is connected to the base 96 of the power module 12. Furthermore, the first sintered connection 130 has a second sintered layer 124, via which the semiconductor element 42 is connected to the first spacer 100.1, and a third sintered layer 126, which connects the first spacer 100.1 to a contact strip 146 of the multifunctional frame 50, so that heat from the contact strip 146 can be dissipated via the third soldered connection 110, the adhesive connection 110 or the third sintered connection 133 via the base 96 to the cooling surface 106. Figure 4The first sintered connection 130 shown in the figure advantageously ensures effective thermal conductivity and electrical reliability. Here, the first, second and third sintered layers 122, 124, 126 of the first sintered connection 130 are made, for example, using a conductive metal powder (such as silver or copper) as the sintering material, wherein excellent electrical and thermal conductivity are achieved by using the first sintered connection 130 according to the present invention with a conductive material. For example, the first, second and third sintered layers 122, 124, 126 of the first sintered connection 130 can be applied by applying conductive metal powder to the surfaces of the components to be connected to each other of the power module 12 or the multifunctional frame 50. In addition, for example, the sintered particles of the sintered material (especially the metal powder) can be fused to each other and to the surface by controlled heating to a suitable temperature to form a strong thermal connection. Alternatively, the first sintered connection 130 can be replaced by a first welded connection 134 or a first soldered connection 108.

[0038] exist Figure 4 The connection of the base 96 of the power module 12 shown in FIG. 1 to the cooling surface 106 can be realized by a second soldered connection 110 (adhesive connection 110 or third sintered connection 133), which can be variably realized. In this case, all connections of the base 96 of the power module 12 to the cooling surface 106 are characterized by effective heat conduction of the heat dissipated by the contact strips 146 through the base 96. These connection methods also provide for optimal adaptation to the tolerances of the surface of the power module 12 that is to come into contact with the cooling surface 106, since the heat dissipated by the contact strips 146 is effectively conducted through the base 96. Figure 4 The connection shown in provides uniform surface contact.

[0039] In addition, Figure 4 , the arrangement of the first plane 60, the second plane 62, and the cooling surface 106 is shown, wherein the second plane 62 is arranged on the cooling surface 106, and the first plane is arranged on the second plane 62. Also shown is the frame 56. The frame 56 laterally surrounds the power module 12. The frame 56 is also shown with the area 113 to be filled with the gel material 112.

[0040] Figure 5 An enlarged view of the second sintered connection 132 is shown.

[0041] exist Figure 5The second sintered connection 132 shown in FIG comprises a fifth sintered layer 129, via which the second spacer 100.2 is connected to the underside of the phase bridge 136, and a fourth sintered layer 128, via which the second spacer 100.2 is connected to the bottom 96 of the power module 12. The second spacer 100.2 is located on the bottom 96 of the power module 12 so that the heat of the phase bridge 136 can be dissipated via the bottom surface 96 via the third sintered connection 133 or the soldered or adhesive connection 110 to the cooling surface 106. Alternatively, the second sintered connection 132 can be replaced by a second welded connection 136 or a second soldered connection 109. Figure 5 Also shown is the filling of the second plane 62 with a gel material 112 .

[0042] Figure 6 An enlarged view of the bond connection 142 is shown.

[0043] exist Figure 6 The bond connections 142 shown in FIG. 1 include an electrical connection between the semiconductor components 42 of the power module 12 and the multifunctional frame 50 via bond wires 140, wherein, for the introduction of the spacers 100.1, 100.2, the bond wires 140 are instead attached to the contact surfaces 102 of the semiconductor components 42 of the power module 12 and the connection pads 138 of the multifunctional frame 50. Alternatively, the electrical connection between the semiconductor components 42 of the power module 12 and the multifunctional frame 50 can also be achieved by introducing a printed circuit board and the bond connections 142.

[0044] The present invention is not limited to the embodiments described herein and the aspects highlighted therein. On the contrary, within the scope defined by the claims, there are numerous possible modifications, which are within the ordinary course of operation of a person skilled in the art.

Claims

1. A power module (12) comprising a circuit carrier (14) comprising a carrier substrate (40) and an electrically insulating layer (16), wherein: The circuit carrier (14) has a first conductor structure (18) with an external contact area (18.2) and at least one second conductor structure (20A, 20B) with at least one external contact area (20A.2, 20B.2), as well as a further third conductor structure (22) with at least one external contact area (22.2); the power module has semiconductor elements (42) arranged individually or in groups (64, 66), characterized in that the power module (12) is equipped with a multifunctional frame (50) and a frame (56), wherein the semiconductor The groups (64, 66) of elements (42) are arranged in a first plane (60) which is spatially separated from a second plane (62) in the multifunctional frame (50), wherein the semiconductor elements (42) are electrically connected to one another via first sintered connections (130) introduced by at least one first spacer (100.1) or via bonding connections (142) introduced by at least one bonding wire (140), wherein the second plane (62) is at least partially surrounded by the frame (56) from the side and is filled with a gel material (112).

2. The power module (12) according to claim 1, characterized in that The semiconductor elements (42) are arranged individually or in groups (64, 66) on a bottom (96) of the power module (12).

3. The power module (12) according to claim 1 and 2, characterized in that The spacers (100.1, 100.2) are arranged in a joining region between the bottom side (120) of the multifunctional frame (50) and the top side of the power module (12).

4. The power module (12) according to any one of claims 1 to 3, characterized in that The first sintered connection (130) comprises a first sintered layer (122), a second sintered layer (124) and a third sintered layer (126).

5. The power module (12) according to any one of claims 1 to 4, characterized in that The first sintered connection (130) can be replaced by a first welded connection (134) or a first soldered connection (108), wherein in both cases a structural unit is formed having a first layer, a second layer and a third layer.

6. The power module (12) according to any one of claims 1 to 5, characterized in that The power module (12) has a second sintered connection (132).

7. The power module (12) according to any one of claims 1 to 6, characterized in that The second sintered connection (132) has a fourth sintered layer (128) and a fifth sintered layer (129).

8. The power module (12) according to any one of claims 1 to 7, characterized in that The second sintered connection (132) can be replaced by a second welded connection (136) or a second soldered connection (109), wherein in both cases a structural unit is formed having a first layer and a second layer.

9. The power module (12) according to any one of claims 1 to 6, characterized in that The power module (12) is connected to the cooling surface (106) via a third solder connection, an adhesive connection (110) or a third sintered connection (133).

10. The power module (12) according to any one of claims 1 to 7, characterized in that Viewed from the Z direction (54), the multifunctional frame (50) is arranged above or below the power module (12).

11. The power module (12) according to any one of claims 1 to 8, characterized in that In the multifunctional frame (50), the conductive components, in particular T+ bridges and T- bridges, are constructed one above the other or side by side, thereby forming a low-inductance connection.

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