阅读说明：本技术 提升大面积焊接可靠性的igbt功率模块散热结构及其方法 (IGBT power module heat dissipation structure and method for improving large-area welding reliability ) 是由 尚敬 罗海辉 康强 常桂钦 董国忠 彭勇殿 曾雄 杨进峰 于 2020-12-16 设计创作，主要内容包括：本发明提供一种提升大面积焊接可靠性的IGBT功率模块散热结构及其方法,包括由上向下依次连接的：半导体芯片元件、第一覆盖层、衬底、第二覆盖层、第一接合材料层、缓冲材料层、第二接合材料层及散热器底板。缓冲材料层的热膨胀系数介于衬底与散热器底板的热膨胀系数之间。本发明在衬板与散热器底板之间添加一种缓冲材料,并引入第二接合材料,缓冲材料层的热膨胀系数介于衬板衬底材质和散热底板材质热膨胀系数之间,在极限工况热冲击循环时可以缓解液冷散热底板与双面金属包覆衬底之间因热膨胀系数大而对冲的问题,降低材质与材质之间热膨胀系数差距,提高了两者之间抗拉伸和抗挤压的能力,提升IGBT器件大面积焊接的可靠性,从而提升模块性能。(The invention provides an IGBT power module heat radiation structure for improving large-area welding reliability and a method thereof, wherein the IGBT power module heat radiation structure comprises the following components which are connected from top to bottom in sequence: the semiconductor device includes a semiconductor chip element, a first cover layer, a substrate, a second cover layer, a first bonding material layer, a buffer material layer, a second bonding material layer, and a heat spreader base plate. The buffer material layer has a coefficient of thermal expansion between that of the substrate and the heat spreader base plate. According to the invention, a buffer material is added between the lining plate and the bottom plate of the radiator, and a second bonding material is introduced, wherein the thermal expansion coefficient of the buffer material layer is between that of the lining plate substrate and that of the heat dissipation bottom plate, so that the problem of hedging between the liquid cooling heat dissipation bottom plate and the double-sided metal cladding substrate due to large thermal expansion coefficient can be relieved during thermal shock circulation under extreme working conditions, the difference of the thermal expansion coefficients between the materials is reduced, the stretching resistance and extrusion resistance between the materials are improved, the reliability of large-area welding of the IGBT device is improved, and the performance of the module is improved.)

1. The utility model provides a promote IGBT power module heat radiation structure of large tracts of land welding reliability which characterized in that, includes from top to bottom and connects gradually: a semiconductor chip element, a first cover layer, a substrate, a second cover layer, a first bonding material layer, a buffer material layer, a second bonding material layer, and a heat spreader base plate.

2. The IGBT power module heat dissipation structure of claim 1, wherein the buffer material layer has a coefficient of thermal expansion between that of the substrate and that of the heat sink base plate.

3. The IGBT power module heat dissipation structure of claim 1, wherein a coefficient of thermal expansion of the first bonding material layer is between a coefficient of thermal expansion of the substrate and a coefficient of thermal expansion of the buffer material layer.

4. The IGBT power module heat dissipation structure of claim 1, wherein the second bonding material layer has a coefficient of thermal expansion between that of the buffer material layer and that of the heat sink base plate.

5. The IGBT power module heat dissipation structure of any one of claims 1 to 4, wherein the heat sink base plate is a base plate adopting a liquid cooling, air cooling or heat pipe heat dissipation manner, and is made of a material with heat conductivity.

6. The IGBT power module heat dissipation structure of claim 5, wherein the substrate is made of a non-metallic material with insulating properties.

7. The IGBT power module heat dissipation structure of claim 6, wherein the buffer material layer is selected from a metal or composite material with a thermal expansion coefficient between the material of the heat sink base plate and the material of the substrate.

8. A method for improving the large-area welding reliability of the heat dissipation structure of the IGBT power module as claimed in any one of claims 1 to 7, characterized by comprising the following steps:

(1) connecting a semiconductor chip element to the first cover layer;

(2) connecting the lower side of the first covering layer with a substrate and a second covering layer in sequence;

(3) connecting the lower side of the second covering layer with the upper side of the buffer material layer through the first bonding material layer;

(4) the underside of the layer of cushioning material is connected to the heat spreader baseplate by a layer of second bonding material.

9. The method of claim 8, wherein the layer of buffer material has a coefficient of thermal expansion that is between the coefficient of thermal expansion of the substrate and the coefficient of thermal expansion of the heat spreader base plate.

10. The method according to claim 8 or 9, wherein the coefficient of thermal expansion of the first bonding material layer is between the coefficient of thermal expansion of the substrate and the coefficient of thermal expansion of the buffer material layer; the thermal expansion coefficient of the second bonding material layer is between that of the buffer material layer and that of the radiator bottom plate.

Technical Field

The invention relates to the field of IGBT device manufacturing, in particular to an IGBT power module heat dissipation structure and method for improving large-area welding reliability.

Background

For power modules, a substrate with a double-sided metal coating, i.e., a "backing plate" (hereinafter referred to as "backing plate"), is typically attached to a base plate by a bonding material, most commonly by soldering or sintering, and the soldered or sintered module is attached to a heat sink by a thermally conductive silicone grease, which together form a power semiconductor assembly.

On the surface of the heat-conducting silicone grease, compared with a metal piece, the heat-conducting silicone grease has lower heat conductivity, after the heat-conducting silicone grease is used for a long time, the distance between partial molecules is increased, the acting force between the molecules is weakened, and the long-term reliability of the interface has problems.

At the module level, the difference between the thermal expansion coefficients of the substrate material of the lining plate and the bottom plate material of the module is not large. If the difference between the substrate material of the lining plate and the bottom plate material of the module is large, the lining plate substrate and the bottom plate material of the module are connected together through the bonding material in a welding or sintering mode, under the application of thermal shock circulation under the limit working condition, the degradation of the bonding material under the lining plate is accelerated, the thermal resistance of the power module is increased, the junction temperature of a chip is increased, and the reliability of the power module is also reduced.

As shown in fig. 1, it is a conventional heat dissipation structure of an IGBT power module. The semiconductor chip component 1 is connected to the first cover layer 3 of the double-sided metal-clad substrate by means of a third bonding material layer 2 in a soldered or sintered manner. The substrate 4 and the second cover layer 5 are connected to the lower side of the first cover layer 3 in sequence, and the first cover layer 3, the substrate 4 and the second cover layer 5 are integrated. The underside of the second cover layer 5 is connected to the heat sink base plate 7 by means of a first bonding material layer 6 by means of soldering or sintering. The material of the substrate 4 and the material of the heat sink base plate 7 have thermal expansion coefficients equivalent to each other, and when a large amount of heat is generated in the semiconductor chip element 1, the heat is transferred to the cover layer 3 through the third bonding material layer 2. The first cover layer 3 transfers heat to the substrate 4 and the second cover layer 5, the second cover layer 5 transfers heat to the first bonding material layer 6 and the heat spreader base plate 7, and the heat spreader base plate 7 transfers heat out.

If the thermal expansion coefficients of the materials of the adjacent layers are equivalent in the process of heat transfer, the Young modulus is not greatly different, so that the adjacent layers or the adjacent layers contract or expand simultaneously, and the whole set of heat dissipation system of the power module is maintained in a balanced state. If the coefficients of thermal expansion of adjacent or adjoining layers are very different and the young's modulus is very different, the structure cannot be balanced any more and the reliability of the power module is greatly reduced.

In view of the above, the present invention provides a heat dissipation structure of an IGBT power module and a method thereof for improving reliability of large area soldering, so as to solve the above technical problems.

Disclosure of Invention

The invention aims to solve the problem that when the thermal expansion coefficient of a lining plate substrate material of a power module is greatly different from that of a bottom radiator bottom plate, the reliability of the power module is low under the thermal shock circulation of the extreme working condition.

In order to achieve the above object, the present invention provides a heat dissipation structure of an IGBT power module for improving reliability of large area welding, which comprises, from top to bottom: a semiconductor chip element, a first cover layer, a substrate, a second cover layer, a first bonding material layer, a buffer material layer, a second bonding material layer, and a heat spreader base plate.

The IGBT power module heat radiation structure is characterized in that the thermal expansion coefficient of the buffer material layer is between the thermal expansion coefficient of the substrate and the thermal expansion coefficient of the radiator bottom plate.

The heat dissipation structure of the IGBT power module is characterized in that the thermal expansion coefficient of the first bonding material layer is between that of the substrate and that of the buffer material layer.

The heat dissipation structure of the IGBT power module is characterized in that the thermal expansion coefficient of the second bonding material layer is between the thermal expansion coefficient of the buffer material layer and the thermal expansion coefficient of the radiator base plate.

The heat dissipation structure of the IGBT power module is characterized in that the base plate of the radiator adopts a liquid cooling, air cooling or heat pipe heat dissipation mode and is made of a material with heat conduction performance.

The IGBT power module heat radiation structure, wherein, the substrate adopts the material that has insulating properties.

The IGBT power module heat radiation structure is characterized in that the buffer material layer is made of metal or composite material with the thermal expansion coefficient between the material of the radiator bottom plate and the material of the substrate.

The invention also provides a method for improving the large-area welding reliability of the heat dissipation structure of the IGBT power module, which comprises the following steps:

(1) connecting a semiconductor chip element to the first cover layer;

(2) connecting the lower side of the first covering layer with a substrate and a second covering layer in sequence;

(3) connecting the lower side of the second covering layer with the upper side of the buffer material layer through the first bonding material layer;

(4) the underside of the layer of cushioning material is connected to the heat spreader baseplate by a layer of second bonding material.

The method of (1), wherein the thermal expansion coefficient of the buffer material layer is between the thermal expansion coefficient of the substrate and the thermal expansion coefficient of the heat sink base plate.

The method of (a), wherein the first bonding material layer has a coefficient of thermal expansion between that of the substrate and that of the buffer material layer; the thermal expansion coefficient of the second bonding material layer is between that of the buffer material layer and that of the radiator bottom plate.

The invention has the beneficial effects that: the buffer material is added between the lining plate and the bottom plate of the radiator, the second bonding material is introduced, the thermal expansion coefficient of the buffer material layer is between the thermal expansion coefficients of the lining plate substrate and the heat dissipation bottom plate, the problem of offset between the liquid cooling heat dissipation bottom plate and the double-sided metal cladding substrate due to large thermal expansion coefficient can be solved during thermal shock circulation under extreme working conditions, the difference of the thermal expansion coefficients between the materials is reduced, the stretching resistance and extrusion resistance between the materials are improved, the integrated module generated by the structure has the characteristics of strong outflow capacity, high interface reliability and the like, the reliability of large-area welding of an IGBT device is improved, and therefore the performance of the module is improved. The buffer material is simple in material selection and is between the thermal expansion coefficients of the two adjacent layers; the cost is low; the assembly is simple, the processing difficulty is low, and the buffering material and the jointing material are bonded together only by welding or sintering.

Drawings

Fig. 1 is a schematic diagram of a conventional heat dissipation structure of an IGBT power module;

fig. 2 is a schematic diagram of a heat dissipation structure of an IGBT power module according to the present invention;

fig. 3 is a schematic perspective view of an embodiment of a heat dissipation structure of an IGBT power module according to the present invention.

Detailed Description

In order to clearly illustrate the inventive content of the present invention, the present invention will be described below with reference to examples.

In the description of the present invention, it should be noted that the terms "upper", "lower", "horizontal", "vertical", "top", "bottom", and the like indicate orientations or positional relationships based on those shown in the drawings, and are only for convenience of description and simplification of description, but do not indicate or imply that the referred device or element must have a specific orientation, be constructed and operated in a specific orientation, and thus, should not be construed as limiting the present invention. Furthermore, the terms "first" and "second" are used for descriptive purposes only and are not to be construed as indicating or implying relative importance.

As shown in fig. 2, the present invention provides a heat dissipation structure of an IGBT power module for improving reliability of large area welding, which comprises, from top to bottom: a semiconductor chip element 1, a third bonding material layer 2, a first cover layer 3, a substrate 4, a second cover layer 5, a first bonding material layer 6, a buffer material layer 8, a second bonding material layer 9, and a heat spreader base plate 7.

Wherein the semiconductor chip component 1 is connected to the first cover layer 3 of the double-sided metal-clad substrate by means of a third bonding material layer 2 in a soldered or sintered manner.

The substrate 4 and the second cover layer 5 are connected to the lower side of the first cover layer 3 in sequence, and the first cover layer 3, the substrate 4 and the second cover layer 5 are integrated.

The lower side of the second cover layer 5 is connected to the buffer material layer 8 by the first bonding material layer 6 by welding or sintering, and the buffer material layer 8 is connected to the radiator support 7 by the second bonding material layer 9 by welding or sintering.

In order to realize high reliability between the radiator bottom plate and the lining plate with larger difference of thermal expansion coefficients and ensure that the power module can have higher reliability under the condition of extreme working condition and high temperature impact cycle, the improvement of the invention is mainly that a buffer material layer 8 is inserted between the first bonding material layer 6 and the radiator bottom plate 7 for stress buffering, and meanwhile, the buffer material layer 8 and the radiator bottom plate 7 are connected through a second bonding material layer 9 in order to ensure the connectivity between the buffer material layer 8 and the radiator bottom plate 7. The second bonding material layer 9 functions to bond the radiator support plate 7 and the cushion material layer 8.

Preferably, the thermal expansion coefficient of the buffer material layer 8 is between the thermal expansion coefficients of the upper and lower layers (the substrate 4 and the heat sink bottom plate 7), and the structure is used for buffering the thermal stress of the materials with different thermal expansion coefficients of the upper and lower layers.

Further, the thermal expansion coefficient of the first bonding material layer 6 is between that of the substrate 4 and that of the buffer material layer 8. Further, the thermal expansion coefficient of the second bonding material layer 9 is between the thermal expansion coefficients of the cushion material layer 8 and the radiator bottom plate 7.

When the material of the substrate 4 thermally expands, the generated thermal stress is transmitted to the buffer material layer 8 through the first bonding material layer 6, because the thermal expansion coefficient difference between the materials of the buffer material layer 8 and the substrate 4 is not large, the thermal deformation amount of the buffer material 8 is small, the force of the first bonding material layer 6 being squeezed or pulled is small, and the degradation speed is reduced.

Similarly, the buffer material layer 8 is thermally expanded, and the generated thermal stress is transmitted to the heat sink base plate 7 through the second bonding material layer 9, because the difference between the thermal expansion coefficients of the materials of the buffer material layer 8 and the heat sink base plate 9 is not large, and the thermal deformation amount of the heat sink base plate 7 is small, the force of extruding or pulling the second bonding material layer 9 is small, the degradation speed of the second bonding material layer 9 is reduced, and the reliability is improved.

Fig. 3 is a schematic perspective view of an embodiment of a heat dissipation structure of an IGBT power module according to the present invention. The base plate of the radiator adopts liquid cooling, air cooling or heat pipe and other heat dissipation modes, and adopts materials with heat conduction performance. The substrate is made of non-metal material with insulating property, such as aluminum nitride, silicon nitride, aluminum oxide, ceramic, and the like. In this embodiment, the radiator bottom plate 7 is a liquid cooling flow channel radiator bottom plate, and is made of aluminum, the thermal expansion coefficient of which is about 23, the substrate 4 is made of aluminum nitride, and the thermal expansion coefficient of aluminum nitride is about 4.5, which has a large difference.

If the double-sided metal-clad substrate 4 is directly welded to the heat sink base plate 7 in the currently common welding manner, a large thermal stress is generated when the substrate is heated, which promotes rapid degradation of the first bonding material layer 6.

However, in the embodiment, the buffer material layer is made of a metal or composite material having a thermal expansion coefficient between that of aluminum and aluminum nitride, such as copper-molybdenum alloy, which has different contents of copper and molybdenum, and the thermal expansion coefficient is adjustable within a certain range. The buffer material layer 8 is used as a blender of the radiator bottom plate 7 and the double-sided metal-coated substrate 4, so that the thermal stress mutation is prevented, the degradation of a joint material is effectively slowed down, and the reliability of the power module is improved. In addition, the buffer material layer 8 is used for connecting the radiator bottom plate 7 and the double-sided metal-coated substrate 4 material, and plays a key role in the process of transferring thermal stress.

The invention also provides a method for improving the large-area welding reliability of the heat dissipation structure of the IGBT power module, which mainly comprises the following steps:

(1) connecting the semiconductor chip element 1 on the first covering layer 3 of the double-sided metal-clad substrate through the third bonding material layer 2 in a welding or sintering mode;

(2) connecting the lower side of the first covering layer 3 with a substrate 4 and a second covering layer 5 in sequence;

(3) the lower side of the second covering layer 5 is connected with the upper side of the buffer material layer 8 through the first bonding material layer 6 in a welding or sintering mode;

(4) the lower side of the cushion material layer 8 is connected to the radiator support 7 by welding or sintering via the second bonding material layer 9.

Preferably, the thermal expansion coefficient of the buffer material layer 8 is between the thermal expansion coefficients of the upper and lower layers (the substrate 4 and the heat sink bottom plate 7), and the structure is used for buffering the thermal stress of the materials with different thermal expansion coefficients of the upper and lower layers.

Further, the thermal expansion coefficient of the first bonding material layer 6 is between that of the substrate 4 and that of the buffer material layer 8. Further, the thermal expansion coefficient of the second bonding material layer 9 is between the thermal expansion coefficient of the cushion material layer 8 and the thermal expansion coefficient of the heat sink base plate 7.

In conclusion, the beneficial effects of the invention are as follows: the buffer material is added between the lining plate and the bottom plate of the radiator, the second bonding material is introduced, the thermal expansion coefficient of the buffer material layer is between the thermal expansion coefficients of the lining plate substrate and the heat dissipation bottom plate, the problem of offset between the liquid cooling heat dissipation bottom plate and the double-sided metal cladding substrate due to large thermal expansion coefficient can be solved during thermal shock circulation under extreme working conditions, the difference of the thermal expansion coefficients between the materials is reduced, the stretching resistance and extrusion resistance between the materials are improved, the integrated module generated by the structure has the characteristics of strong outflow capacity, high interface reliability and the like, the reliability of large-area welding of an IGBT device is improved, and therefore the performance of the module is improved. The buffer material is simple in material selection and is between the thermal expansion coefficients of the two adjacent layers; the cost is low; the assembly is simple, the processing difficulty is low, and the buffering material and the jointing material are bonded together only by welding or sintering.

While the invention has been described with reference to a preferred embodiment, various modifications may be made and equivalents may be substituted for elements thereof without departing from the scope of the invention. In particular, the technical features mentioned in the embodiments can be combined in any way as long as there is no structural conflict. It is intended that the invention not be limited to the particular embodiments disclosed, but that the invention will include all embodiments falling within the scope of the appended claims.