Double-sided water-cooled power module with plural power semiconductor elements

Abstract

The utility model discloses a double-sided water-cooled power module with a plurality of power semiconductor elements, which mainly comprises a watertight shell and a power element package, and the power element package mainly comprises a lower side ceramic mainboard, the power semiconductor elements, a copper saddle-shaped upper guide pillar, an upper side ceramic cover plate, a shunt support pillar and a resin insulation package. Wherein the bottom surface electrode of the power semiconductor element is correspondingly pressure-welded with the silver film layer, and the top surface electrode is pressure-welded with the interface silver film layer, and finally is insulated and packaged by resin; the power semiconductor element is connected with the lower side ceramic main board in a pressing mode through the silver thin film layer, the copper saddle-shaped upper guide column is welded to the power semiconductor element in a pressing mode through the interface silver thin film layer, then a conductive loop is completed, and meanwhile the watertight shell is matched to achieve the double-face heat dissipation effect.

Description

Technical Field

[0001] The utility model relates to a double-sided water-cooled power module with a plurality of power semiconductor elements. Background Art

[0002] As countries around the world formulate strategies for energy transitions in the automotive industry, vehicles previously powered by fossil fuels are gradually being replaced by electric vehicles powered by electricity. Because electric vehicles rely on high-power electric motors for propulsion, market demand for high-power power modules is growing significantly and rapidly. Of course, high-power power modules consume a lot of energy, and some of that energy is inevitably converted into heat. When operating in a small space, the heat generated by some high-power components can reach even higher temperatures. Therefore, controlling the heat temperature within a certain range and ensuring environmental stability are crucial.

[0003] Ceramic materials, used as insulating materials in circuit substrates, have a thermal expansion coefficient and high heat resistance similar to those of semiconductors. Their thermal conductivity is particularly superior to that of resin substrates, which can provide complex multilayer structures. Therefore, ceramic materials are currently the primary substrate material for high-power power modules. However, as ceramic substrates increase in size, they inevitably experience irregular warping during the sintering process, resulting in an uneven surface. Consequently, circuit components mounted on the substrates will also experience slight height variations, such as unevenness and unevenness after installation. In typical circuit configurations, these tolerances are not a problem.

[0004] As the currents carried by power components and power modules increase, heating and heat dissipation issues in power modules are becoming increasingly serious. The original structure that relied solely on a single-sided ceramic substrate for heat dissipation is no longer sufficient. Therefore, a dual-ceramic substrate architecture has emerged, which requires heat dissipation from both the top and bottom surfaces of the power components. High-power power modules use two ceramic substrates on the top and bottom sides as a heat dissipation structure to improve thermal conductivity and heat dissipation efficiency.

[0005] According to current technology, power semiconductor components are soldered to the pads of a ceramic substrate using nanosilver paste as a wet, or soft, adhesive. Reflowing the nanosilver paste creates a silver bond between the ceramic substrate's pads and the chip's input / output electrodes, providing both electrical and thermal conductivity, and compensating for poor connections caused by dimensional tolerances. However, because this nanosilver paste contains other materials, its overall electrical and thermal conductivity after curing is inferior to that of a solid metal connection. Using nanosilver paste exclusively would inevitably limit these electrical and thermal conductivity levels. Even a slight increase in resistance can significantly increase thermal resistance under high-current operating conditions, further hindering heat dissipation. This not only affects performance, wastes the electric vehicle's limited stored energy, reduces vehicle range, and even shortens the lifespan of the electronic control system, but also reduces the overall thermal and electrical conductivity of the power semiconductor components. The challenge in this field is to simultaneously improve the thermal and electrical conductivity of the power semiconductor components, while also addressing the height differences between multiple power semiconductor components caused by ceramic substrate warping and preventing damage caused by excessive stress. Utility Model Content

[0006] In view of the above-mentioned deficiencies of the prior art, according to an embodiment of the present invention, it is hoped to provide a double-sided water-cooled power module with multiple power semiconductor elements, aiming to achieve the following purposes: (1) by using a silver film as a linking structure between the lower electrode of the power semiconductor element and the mounting pad, the heat conduction and electrical conduction efficiency below the power semiconductor is greatly improved, thereby ensuring the heat dissipation capacity of the operating environment; (2) through the copper saddle-shaped upper guide column, the heat energy generated on the upper side of the power semiconductor element can also be effectively transferred from the upper ceramic cover plate to the upper heat-conducting shell; (3) by using the silver glue welding between the shunt support column and the upper ceramic cover plate, compensation for the warping of the ceramic substrate is provided, the risk of damage to the power semiconductor caused by upper and lower pressure welding is reduced, and the module yield is improved; (4) the power semiconductor element is transferred to the lower heat-conducting shell through the lower ceramic main board, and the cooling liquid channels formed in the upper heat-conducting shell and the lower heat-conducting shell respectively achieve double-sided heat removal, thereby improving the heat dissipation effect of the overall power semiconductor element.

[0007] To achieve the above-mentioned object, the present invention provides a double-sided water-cooled power module with a plurality of power semiconductor elements, comprising: a watertight housing, the watertight housing comprising an upper heat-conducting shell and a lower heat-conducting shell, the upper heat-conducting shell and the lower heat-conducting shell each having at least one cooling liquid channel formed therein; and a plurality of power element packages, each of which is heat-conductingly sandwiched between the upper heat-conducting shell and the lower heat-conducting shell, each of which comprises a lower ceramic motherboard having an upper surface and a bottom surface abutting against the lower heat-conducting shell; a plurality of metal pad blocks formed on the upper surface, and a plurality of power semiconductor mounting pads insulated from each other and from the metal pad blocks, wherein each of the power semiconductor mounting pads is press-welded with a silver film layer; and a plurality of power semiconductor elements corresponding to the number of the power semiconductor mounting pads, each of which is heat-conductingly sandwiched between the upper heat-conducting shell and the lower heat-conducting shell. Each of the power semiconductor elements has a bottom electrode, two top electrodes spaced apart from each other, and at least one top gate insulated from the top electrodes; wherein the bottom electrode of each power semiconductor element is respectively press-welded to the silver film layer, and an interfacing silver film layer is press-welded to each top electrode; a plurality of copper saddle-shaped upper guide pillars corresponding to the number of the power semiconductor elements have two feet respectively press-welded to the interfacing silver film layer; an upper ceramic cover plate has a heat-conducting top surface and a bottom surface, and a plurality of bottom pads press-welded to the copper saddle-shaped upper guide pillars are formed below the bottom surface; a plurality of shunt support pillars, one end of the shunt support pillars is welded to the metal pad block, and the other end opposite to the end is welded to the bottom pad by silver glue; and a resin insulation package that completely covers the power semiconductor element, the copper saddle-shaped upper guide pillar, and the shunt support pillars.

[0008] Compared to existing technologies, the present invention utilizes a pressure-welded silver film for conductive connection, resulting in excellent electrical and thermal conductivity between the power semiconductor element and the power semiconductor mounting pads on the lower ceramic motherboard. The silver film itself far outperforms traditional nanosilver paste in both electrical and thermal conductivity. In particular, its thickness can be as thin as approximately 20 microns (μm) and its high uniformity ensures that even large-area ceramic substrates experience significant warping and height differences. However, the relatively small size of the power semiconductor reduces this warping, resulting in a very good fit at the joint. Furthermore, the tight pressure welding process eliminates microscopic air gaps at the joint interface, ensuring a stable and ideal joint. This structural design allows the heat generated by the power semiconductor element, the primary heat source, to be efficiently transferred downward to the lower ceramic motherboard.

[0009] Secondly, above the power semiconductor components, a silver film is similarly bonded to the copper saddle-shaped upper guide post. This allows heat generated by the power semiconductor components to be efficiently transferred to the upper guide post and then toward the upper ceramic cover. Because the lower ceramic mainboard and upper ceramic cover abut the lower and upper thermally conductive housings, respectively, heat from the power semiconductor components can be dissipated in both directions. In particular, the lower conductor path is short, the conductor interface is tightly sealed, and the thermal resistance of the conductor path is low, effectively improving existing technology in terms of ensuring heat dissipation efficiency.

[0010] Furthermore, compared to the large surface area of the lower ceramic mainboard and upper ceramic cover, the height difference caused by warping becomes significant. If silver film were used to completely replace the existing silver glue, unexpected structural pressure would be applied to any undefined protruding parts. If the pressure happened to be on a power semiconductor component, microcracks would result, leading to damage. Even worse, the performance would fluctuate, and the impact after passing quality control and being installed on the vehicle would be even more difficult to estimate. Therefore, the present invention retains the use of silver glue between the multiple external shunt support columns and the bottom pads of the upper ceramic cover. Even at the expense of some thermal conductivity, it still provides good mechanical cushioning. The soft properties of the silver glue before curing provide a good cushioning effect when the upper ceramic cover is pressed down. This softness also allows for a wider range of dimensional errors. Furthermore, the multiple shunt support columns effectively limit the height of the upper ceramic cover, thereby preventing overpressure on the copper saddle-shaped upper guide column and damaging the power semiconductor components. BRIEF DESCRIPTION OF THE DRAWINGS

[0011] Figure 1 This is a side view schematic diagram of the structure of the power component package assembled in the watertight housing of the present invention.

[0012] Figure 2 This is a schematic diagram of the distribution position of the cooling liquid channels of the present invention.

[0013] Figure 3 A three-dimensional schematic diagram of a power component package.

[0014] Figure 4 A schematic diagram of a three-dimensional exploded view of the power component package.

[0015] Figure 5 This is a three-dimensional diagram of the bottom surface of the upper ceramic mainboard.

[0016] Figure 6 This is a three-dimensional schematic diagram of the distribution structure of the metal pad block and power semiconductor mounting pads in the lower ceramic motherboard.

[0017] Figure 7 A three-dimensional schematic diagram of the structure of the silver thin film layer bonded to the power semiconductor mounting pad.

[0018] Figure 8 A three-dimensional schematic diagram of the structure of a power semiconductor element bonded to a silver thin film layer.

[0019] Figure 9 This is a three-dimensional schematic diagram of the pressure welding of the copper saddle-shaped upper guide column and the diversion support column.

[0020] Figure 10 for Figure 9 An enlarged view of part A (stereoscopic diagram of the copper saddle-shaped upper guide column).

[0021] Figure 11 for Figure 9 An enlarged view of part B (a three-dimensional schematic diagram of the pressure welding of the diversion support column).

[0022] Among them: 1 is a watertight shell; 10 is an upper heat-conducting shell; 12 is a lower heat-conducting shell; 14 is a cooling liquid channel; 2 is a power component package; 20 is a lower ceramic motherboard; 200 is an upper surface; 202 is a bottom surface; 21 is a power semiconductor component; 210 is a bottom electrode; 212 is a top electrode; 214 is a top gate; 22 is a copper saddle-shaped upper guide column; 220 is a foot; 23 is an upper ceramic cover; 230 is a heat-conducting top surface; 232 is a lower surface; 234 is a bottom pad; 24 is a shunt support column; 25 is a resin insulation package; 26 is a metal pad block; 27 is a power semiconductor mounting pad; 28 is a silver film layer; 29 is an interfacing silver film layer; 3 is a driving component. DETAILED DESCRIPTION

[0023] The following describes the implementation of the present invention through specific embodiments. People skilled in the art can easily understand other advantages and effects of the present invention from the contents disclosed in this specification.

[0024] The structures, proportions, sizes, etc. illustrated in the drawings of this specification are only used to match the contents disclosed in this specification for the understanding and reading of those familiar with this technology. They are not used to limit the conditions for the implementation of this utility model and therefore have no substantial technical significance. Any structural modifications, changes in proportional relationships, or adjustments in size, without affecting the effects and objectives that can be achieved by this utility model, should still fall within the scope of the technical content disclosed by this utility model. At the same time, terms such as "one", "two", "on", etc. quoted in this specification are only for the convenience of description and are not used to limit the scope of the implementation of this utility model. Changes or adjustments in their relative relationships, without substantially changing the technical content, should also be considered as the scope of the implementation of this utility model.

[0025] like Figure 1-4As shown, a preferred embodiment of the present invention provides a double-sided water-cooled power module with multiple power semiconductor elements, which mainly includes a watertight housing 1 and a power element package 2. The watertight housing 1 includes an upper heat-conducting shell 10 and a lower heat-conducting shell 12, and at least one cooling liquid channel 14 is formed in each of the upper heat-conducting shell 10 and the lower heat-conducting shell 12. The power element package 2 is heat-conductingly sandwiched between the upper heat-conducting shell 10 and the lower heat-conducting shell 12. The power element package 2 mainly includes a lower ceramic mainboard 20, a power semiconductor element 21, a copper saddle-shaped upper guide column 22, an upper ceramic cover plate 23, a shunt support column 24 and a resin insulation package 25.

[0026] For reference Figure 5-11 It can be clearly understood that in the aforementioned power device package 2 , the upper ceramic cover 23 has a heat-conducting top surface 230 and a lower surface 232 , and a plurality of bottom pads 234 are formed below the lower surface 232 .

[0027] The lower ceramic mainboard 20 has an upper surface 200 and a bottom surface 202 that abuts the lower heat-conducting housing 12. A plurality of metal pad blocks 26 and power semiconductor mounting pads 27 are formed on the upper surface 200. Each metal pad block 26 and power semiconductor mounting pad 27 is insulated from each other. Silver film layers 28 are press-welded onto the power semiconductor mounting pads 27. Each silver film layer 28 is press-bonded to a power semiconductor element 21. Therefore, the number of power semiconductor mounting pads 27 corresponds to the number of power semiconductor elements 21.

[0028] Each power semiconductor element 21 comprises a bottom electrode 210, two spaced-apart top electrodes 212, and at least one top gate 214 insulated from the top electrodes 212. The bottom electrode 210 of each power semiconductor element 21 is bonded to the aforementioned silver thin film layer 28, and an interfacing silver thin film layer 29 is bonded to each top electrode 212. As mentioned above, while the lower ceramic motherboard may experience significant warping during mass production, the height difference caused by this warping is negligible within a small range, considering the corresponding dimensions of any power semiconductor element. Therefore, even with bonded welding, there is no concern about damage to the power semiconductor element. The bottom electrodes of the power semiconductor elements are securely and firmly bonded to the power semiconductor mounting pads through the silver thin friction layer. Furthermore, heat generated by the bottom of the power semiconductor element can be effectively conducted to the lower ceramic motherboard and carried away by cooling water. Furthermore, considering that the overall thickness of the silver film layer and the power semiconductor mounting pad is extremely thin, the temperature gradient between the power semiconductor element and the lower heat-conducting housing below is very large. According to the heat transfer formula, the heat energy conduction efficiency will be particularly excellent.

[0029] Each power semiconductor element 21 is provided with a corresponding copper saddle-shaped upper guide pin 22. Each of these copper saddle-shaped upper guide pins 22 has two legs 220, each of which is press-welded to an interposing silver film layer 29. The other side of the copper saddle-shaped upper guide pin 22 is press-welded to a bottom pad 234 of the upper ceramic cover plate 23. This ensures that the top electrode above the power semiconductor element is effectively connected to the copper saddle-shaped upper guide pin via the interposing silver film layer. Because the height of the copper saddle-shaped upper guide pin is approximately 2 mm, the temperature gradient on the upper side is relatively small compared to the height gradient on the lower side, making it only a minor heat dissipation pathway. Therefore, a silver film or silver glue can be used between the copper saddle-shaped upper guide pin and the bottom pad of the upper ceramic cover plate, depending on the application.

[0030] Each of the numerous shunt support pillars 24 has one end welded to any location within the metal pad block 26, and the other end soldered to the bottom pad 234 of the upper ceramic cover plate using silver glue. Because the shunt support pillars 24 are made of all-metal, they are more resistant to pressure than semiconductor components. The silver glue is relatively soft before curing, providing a buffering effect. Furthermore, the shunt support pillars 24 are not located in the primary heat dissipation path of the power semiconductor components. Even if a slight gap is created during the soldering process, creating some thermal resistance, it will not cause significant overheating for the entire module. This allows the shunt support pillars to fulfill their inherent conductive function while also providing support for the downward pressure of the upper ceramic cover plate, preventing damage to the power semiconductor components from excessive compression. Furthermore, the silver glue bonding provides a buffering effect, compensating for the warpage height difference between the upper ceramic cover plate and the lower ceramic main plate. Finally, a resin insulation package 25 completely encapsulates the power semiconductor components 21, the copper saddle-shaped upper guide pillars 22, and the shunt support pillars 24.

[0031] As can be seen from the above, the complete conductive circuit is mainly through the power semiconductor element 21 in the power element package 2, through the bottom electrode 210 corresponding to the silver film layer 28 press-welded to the lower ceramic motherboard 20, the top electrode 212 press-welded with the intermediate silver film layer 29 is set on the upper ceramic cover 23 through the copper saddle-shaped upper guide 22, and the top gate 214 is connected to the driving element 3. Each power semiconductor element 21 in each power element package 2 is driven by the driving element 3 to Figure 2In the embodiment, three groups of power element packages 2 are taken as an example. Each power element package 2 is divided into a plurality of power semiconductor elements 21 in the left half and a plurality of power semiconductor elements 21 in the right half. The plurality of power semiconductor elements 21 in the left half and the right half of each power element package 2 are driven in turn or not driven at all. When the three groups of power element packages 2 are used as packages, the driving method is that two of the three groups will select half of the power semiconductor elements 21 to drive, and the other group will not drive at all. In short, the three groups of power element packages 2 are divided into six halves of power semiconductor elements 21, and only two halves are driven and used.

[0032] The driven power element package 2 has a conductive circuit in which electrical energy is transmitted primarily through the conductive terminals to the lower ceramic mainboard 20, then to the power semiconductor element 21 via the power semiconductor mounting pads 27 and the silver film layer 28. The electrical energy is then transmitted via the intervening silver film layer 29 on the power semiconductor element 21 to the copper saddle-shaped upper guide post 22, then through the upper ceramic cover plate 23 to the shunt support post 24, and finally output through the planar terminals, thereby completing the overall conductive circuit.

[0033] On the other hand, to dissipate heat generated by each power semiconductor element 21 within the power device package 2 through double-sided heat conduction through the watertight housing 1, the power device package 2 is mounted and abutted between an upper heat-conducting housing 10 and a lower heat-conducting housing 12, each of which has cooling liquid channels 14. The multiple power semiconductor elements 21 within the power device package 2 are mounted on a lower ceramic motherboard 20 with power semiconductor mounting pads 27 through a silver film layer 28. Heat is transferred through the cooling liquid channels 14 on the lower ceramic motherboard 20. The spaced-apart top electrodes 212 on the power semiconductor elements 21 are bonded to the feet 220 of the copper saddle-shaped upper guide posts 22 via respective pressure-welded intermediate silver film layers 29. The other side of the copper saddle-shaped upper guide posts 22 is bonded to the bottom pads 234 of the upper ceramic cover plate 23. This allows heat to be transferred from the copper saddle-shaped upper guide posts 22 to the upper ceramic cover plate 23 and then through the cooling liquid channels 14. Furthermore, the silver film layer 28 and the interfacing silver film layer 29 are both made of dry silver, which can effectively eliminate air gaps through high-temperature welding while having good flat contact, thereby improving the overall heat conduction effect.

[0034] In addition, since the power semiconductor element 21 is press-welded with the interfacing silver film layer 29 and the silver film layer 28 on the upper and lower sides respectively, and both the interfacing silver film layer 29 and the silver film layer 28 are dry conductive materials, in order to prevent the copper saddle-shaped upper guide post 22 from causing damage to the power semiconductor element 21 due to overpressure, multiple shunt support posts 24 are used to effectively limit the height to which the upper ceramic cover plate is pressed down. Furthermore, the other end of the shunt support post 24 is welded to the bottom surface pad 234 of the upper ceramic cover plate 23 using silver glue. The soft properties of the silver glue itself can achieve a good buffering effect when the upper ceramic cover plate 23 is pressed down, thereby preventing overpressure on the copper saddle-shaped upper guide post from causing damage to the power semiconductor element.

Claims

1. A double-sided water-cooled power module having a plurality of power semiconductor elements, characterized in that: include: a watertight housing, the watertight housing comprising an upper heat-conducting shell and a lower heat-conducting shell, at least one cooling liquid channel being formed in each of the upper heat-conducting shell and the lower heat-conducting shell; as well as A plurality of power component packages are placed between the upper heat-conducting housing and the lower heat-conducting housing by heat-conducting clips, each of which includes a lower ceramic mainboard having an upper surface and abutting against the bottom surface of the lower heat-conducting housing; a plurality of metal pad blocks formed on the upper surface, and a plurality of power semiconductor mounting pads insulated from each other and from the metal pad blocks, wherein a silver film layer is press-welded onto each of the power semiconductor mounting pads; A plurality of power semiconductor elements corresponding in number to the power semiconductor mounting pads, each of the power semiconductor elements comprising a bottom electrode, two top electrodes spaced apart from each other, and at least one top gate insulated from the top electrodes; The bottom electrodes of each of the power semiconductor elements are respectively connected to the silver thin film layer by pressure welding, and an interfacing silver thin film layer is respectively pressure welded to each of the top electrodes; A plurality of copper saddle-shaped upper guide pillars corresponding to the number of the aforementioned power semiconductor elements, each having two feet respectively press-welded to the aforementioned interfacing silver film layer; An upper ceramic cover plate having a heat-conducting top surface and a lower surface, wherein a plurality of bottom pads are formed below the lower surface and are press-welded to the copper saddle-shaped upper guide pillars; A plurality of shunt support columns, one end of each shunt support column being welded to the metal pad block, and the other end opposite to the end being welded to the bottom pad with silver glue; as well as A resin insulation package completely covers the power semiconductor element, the copper saddle-shaped upper guide column, and the shunt support column.

2. The double-sided water-cooled power module having a plurality of power semiconductor elements according to claim 1, wherein: A silver film is respectively press-welded between each of the aforementioned shunt support pillars and the aforementioned metal pad block.

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