Performance module

Abstract

Power module (100) which includes the following: - an insulating substrate (2) on the first surface of which a semiconductor element (3) is formed; - a base plate (1) connected to a second surface of the insulating substrate (2); - a housing element (6) that surrounds the insulating substrate (2) and is in contact with a surface of the base plate (1) that is connected to the second surface of the insulating substrate (2); - a sealing resin (8) that fills an area surrounded by the base plate (1) and the housing element (6) to seal the insulating substrate (2); - a pressure plate (9) which is arranged in close contact with an opposite surface of the sealing resin (8) with respect to the first surface of the insulating substrate (2); and - a cover element (7) which faces an opposite surface of the pressure plate (9) with respect to its surface in close contact with the sealing resin (8), and which is attached to the housing element (6) in a position which prevents the pressure plate (9) from moving further upwards towards the cover element (7) when it touches the cover element (7), wherein there is a gap between the cover element (7) and a surface of the sealing resin (8) at normal temperature, and wherein a change in height of the sealing resin (8) at an operating temperature of the power module (100) of 150°C corresponds to this gap, and wherein when the operating temperature of the power module (100) is 150°C or higher, the pressure plate (9) reaches the cover element (7).

Description

Technical field

[0001] The present invention relates to a sealing structure of a power module in which power semiconductor elements are sealed with resin. State of the art

[0002] A semiconductor element of a specific type, whose electrical path runs vertically to allow it to handle high voltage and current, is generally referred to as a power semiconductor element (for example, IGBT (insulated-gate bipolar transistor), MOSFET (metal-oxide-semiconductor field-effect transistor), bipolar transistor, and diode). Power semiconductor elements are mounted on a circuit substrate and encapsulated with a sealing resin to form a power module, which is used in a wide range of applications, such as industrial machinery, vehicles, and railway equipment.

[0003] With the improved performance of the equipment fitted with power modules, there has recently been an increased demand for a high-performance power module that has a higher rated voltage, a larger rated current, or an extended operating temperature range (higher temperature, lower temperature).

[0004] Regarding the packaging structure or housing structure of the power modules, a structure primarily used is referred to as a package-type design. A package-type power module has a structure in which the power semiconductor elements are mounted on a heat-dissipating base plate with an insulating substrate in between, and in which the housing is connected to the base plate. The semiconductor elements contained in the power module are connected to a main electrode.

[0005] Bonding wires are used to connect the power semiconductor element and the main electrode. Generally, an insulating gel-like filler, represented by silicone gel, is used as a sealing resin for the power module to prevent insulation failure when a high voltage is applied.

[0006] A conventional power module is known (see, for example, patent document 1) in which, in order to prevent the bonding wires from breaking as a result of shaking the silicone gel, a press cap is inserted to come into close contact with the upper surface of the silicone gel, and projections are formed on the sides of the press cap to engage movably in the upward and downward direction with the inner wall of the outer circumferential housing.

[0007] Furthermore, another power module is known (see, for example, patent document 2) which has a lid for covering the upper surface of the silicone gel, wherein the end regions of the lid are attached to the housing, and at least 80% of the upper surface is in contact with the lid in a usable temperature range.

[0008] Patent document 3 discloses a semiconductor device comprising a semiconductor element in a housing, a bonding wire, a sealing resin element covering the semiconductor element and the bonding wire, and a foil element. The foil element is fixed within the housing and positioned outside of contact with the bonding wire, and is furthermore embedded in the sealing resin element. Because the foil element dampens the vibrations of the sealing resin, the bonding wire is connected with improved reliability. A column element mounted on an insulating substrate can also be used instead of the foil element. The semiconductor device is suitable for use on a mobile body, such as a vehicle, that is subject to vibrations.

[0009] Patent document 4 discloses a semiconductor device in which the air within a gel resin can be effectively and thoroughly cleaned. The device comprises a housing, a semiconductor device electrically connected by bond wires, and a gel resin filled into the housing, serving as an insulating cover for the semiconductor device and the bond wire. The device further includes a plate-shaped vibration damper in contact with the gel resin, provided with a plurality of perforations, each having an air inlet and an air outlet for the purpose of air extraction during the filling of the gel resin. The cross-sectional area of ​​the perforations is tapered and larger at the inlet than at the outlet, so that the perforations as a whole have the shape of a substantially conical trapezoid.

[0010] Patent document 5 discloses a technology that maintains insulation against the outside air, thereby preventing deterioration of quality, and which continuously utilizes the current external shape and basic structure to enable simple implementation in a power module. Such a power module comprises: a housing; a base plate arranged at a lower end of the housing; a chip arranged on the base plate and serving as a power element; a silicone gel sealing the chip; a thin film element covering a surface of the silicone gel and having a thickness such that the film element flexes to accommodate the movement of the silicone gel; and a cover element arranged at an upper end of the housing.

[0011] Patent document 6 discloses a power semiconductor module comprising a power semiconductor chip having an electrical contact surface on its upper side to which a bond wire is bonded. At least when the power semiconductor module is attached to a heat sink, a clamping element generates a clamping force acting on a portion of the bond wire formed between two adjacent bond points. This clamping force presses the power semiconductor chip and any underlying substrate against the heat sink. State of the art patent document Patent document 1: JP 2000 - 311 970 A (page 3, Fig. 1) Patent document 2: JP 2014 - 130 875 A (page 4, Fig. 1) Patent document 3: US 2003 / 0 011 057 A1 Patent document 4: US 6,791,174 B2 Patent document 5: JP 2014 - 150 204 A Patent document 6: DE 10 2009 002 191 A1 Summary of the invention Problem to be solved with the invention

[0012] Generally, the amount of gas that can be dissolved in the silicone gel decreases as the temperature increases. Therefore, an expansion of the operating temperature range of power modules results in a higher operating temperature for the silicone gel, which means that gas-formed bubbles can no longer be dissolved within the gel. At the points where the bubbles are formed, separation occurs between the silicone gel and the insulating substrate (wiring pattern), rendering the insulating seal provided by the silicone gel ineffective and degrading the insulating performance of the power module.

[0013] To prevent the formation of bubbles and detachments in the silicone gel, the internal stress on the silicone gel should be applied as a compressive load. This is because tensile stress acts as a driving force to create and expand the bubbles and detachments.

[0014] However, with regard to the power module specified in patent document 1, the following applies: Even when the press-fit lid is inserted to come into close contact with the upper surface of the sealing resin, the thermally expanded sealing resin can easily push the press-fit lid upwards when the power semiconductor elements are operated at a high temperature, as the press-fit lid is movable up and down along the inner wall of the outer perimeter housing. Therefore, no pressure load is generated to prevent the formation of bubbles. This impairs the insulating properties of the power module.

[0015] Regarding the power module described in patent document 2, the following applies: Since the end regions of the lid are attached to the housing, the thermally expanded silicone gel cannot push the pressure plate upwards at high temperatures, and the internal stress on the silicone gel becomes a pressure load to prevent bubble formation. However, at low temperatures, the following applies: Since the lid end sections are attached to the housing, the thermally shrunk silicone gel is pulled away from the lid, resulting in a tensile stress. This internal tensile stress in the silicone gel expands any microbubbles contained within it. The tensile stress also causes delamination, or leads to delamination, at interfaces if there is an area of ​​reduced adhesion at the interface between the silicone gel and the insulating substrate, the interface between the silicone gel and the power semiconductor elements, or the interface between the gel and the wire. At the points where bubbles are generated or delamination occurs, the insulating seal provided by the silicone gel is weakened. This degrades the insulating performance of the power module.

[0016] At higher operating temperatures of the power module, smaller bubbles or minor delaminations can also cause dielectric breakdown. This leads to a deterioration of the insulation performance in the power module.

[0017] As explained above, the following applies: If conventional power modules are used at a higher temperature or a lower temperature as a result of the expansion of the operating temperature range of the power modules, or if conventional power modules are used at a high operating voltage, then the insulation performance of the conventional power modules is deteriorated.

[0018] The present invention was designed to solve the problem described above. The object of the invention is to provide a power module that ensures insulating performance when used at high temperature, low temperature, or high operating voltage, and in which the formation of bubbles and delamination between a silicone gel and an insulating substrate is prevented. Ways to solve the problem

[0019] The problem underlying the invention is solved by a power module with the features of independent claim 1. Advantageous embodiments of the power module according to the invention are specified in dependent claims 2 to 6. Effect of the invention

[0020] According to the present invention, the pressure plate is arranged between the sealing resin in the module and the cover therein, so that it is in close contact with the sealing resin. This can mitigate thermal stresses generated during the thermal cycles in the sealing resin that is filled into the housing and the insulating substrate, which can improve the reliability of the module during thermal cycles. Brief description of the drawings Fig. Figure 1 is a schematic cross-sectional view of the structure of a power module according to embodiment 1 of the present invention. Fig. Figure 2 is a schematic cross-sectional view of the structure of the power module according to embodiment 1 of the present invention, the temperature of which is low. Fig. Figure 3 is a schematic cross-sectional view of the structure of the power module according to embodiment 1 of the present invention, the temperature of which is high. Fig. Figure 4 is a schematic cross-sectional view of the structure of a power module according to embodiment 2 of the present invention. Fig. Figure 5 is a schematic cross-sectional view of the structure of the power module according to embodiment 2 of the present invention, the temperature of which is low. Fig. Figure 6 is a schematic cross-sectional view of the structure of the power module according to embodiment 2 of the present invention, the temperature of which is high. Fig. Figure 7 is a schematic top view of the structure of a cover of the power module according to embodiment 2 of the present invention. Fig. Figure 8 is a schematic top view of the structure of a further cover of the power module according to embodiment 2 of the present invention. Fig. Figure 9 is a schematic top view of the structure of a further cover of the power module according to embodiment 2 of the present invention. Fig. Figure 10 is a schematic top view of the structure of a further cover of the power module according to embodiment 2 of the present invention. Fig. Figure 11 is a schematic top view of the structure of a further cover of the power module according to embodiment 2 of the present invention. Fig. Figure 12 is a schematic top view of the structure of a further cover of the power module according to embodiment 2 of the present invention. Fig. Figure 13 is a schematic top view of the structure of a further cover of the power module according to embodiment 2 of the present invention. Fig. Figure 14 is a schematic cross-sectional view of the structure of a power module according to embodiment 3 of the present invention. Fig. Figure 15 is a schematic top view of the structure of a press plate of the power module according to embodiment 3 of the present invention. Fig. Figure 16 is a schematic top view of the structure of a further press plate of the power module according to embodiment 3 of the present invention. Fig. Figure 17 is a schematic cross-sectional view of the structure of a power module according to embodiment 4 of the present invention. Fig. Figure 18 is a schematic cross-sectional view of the structure of a further cover and a further press plate of the power module according to embodiment 4 of the present invention. Fig. Figure 19 is a schematic cross-sectional view of the structure of a further cover and a further press plate of the power module according to embodiment 4 of the present invention. Fig. Figure 20 is a schematic cross-sectional view of the structure of a further cover and a further press plate of the power module according to embodiment 4 of the present invention. Fig. Figure 21 is a schematic cross-sectional view of the structure of a power module according to embodiment 5 of the present invention. Fig. Figure 22 is a schematic cross-sectional view of the structure of a further cover and of pressure plates of the power module according to embodiment 5 of the present invention. Fig. Figure 23 is a schematic cross-sectional view of the structure of a power module according to embodiment 6 of the present invention. Embodiments for carrying out the invention

[0021] The following section describes in detail embodiments of semiconductor devices according to the present invention with reference to the figures.

[0022] It should be noted that the present invention is not limited to what is described below, and that it can be suitably modified within the essential scope of the present invention. Design 1

[0023] Fig. Figure 1 is a schematic cross-sectional view of the structure of a power module according to embodiment 1 of the present invention. As shown in Fig. As shown in Figure 1, a power module 100 comprises the following: a base plate 1, an insulating substrate 2, power semiconductor elements 3, each functioning as a semiconductor element, bonding wires 4, terminals 5, a housing 6, which functions as a housing element, a cover 7, which functions as a cover element, silicone gel 8, which is a sealing resin, a press plate 9, and solder 11 and 12.

[0024] The lower side surface (“the other surface”) of the insulating substrate 2 is soldered to the base plate 1 with solder 12. The insulating substrate 2 has an insulating layer 21 and metal plates 22 and 23. The insulating substrate 2 has a structure in which the metal plates 22 and 23, which are made of copper, aluminum, or the like, are bonded to the two respective surfaces of the insulating layer 21, which is made of aluminum oxide, aluminum nitride, a ceramic such as silicon nitride, epoxy resin, or the like.

[0025] A wiring pattern is formed on the metal plate 23, which corresponds to the upper side surface (“the one surface”) of the insulating substrate 2. The power semiconductor elements 3 are soldered to the metal plate 22 of the upper side surface using solder 11. Here, solder is used as the bonding material. However, the bonding material to be used is not limited to solder. Other materials or techniques, such as sintered silver, a conductive adhesive, or a liquid-phase diffusion bonding technique, can also be used.

[0026] The power semiconductor elements 3 comprise MOSFETs (metal oxide semiconductor field-effect transistors), power control semiconductor elements such as IGBTs (insulated-gate bipolar transistors), freewheeling diodes, and the like. The power semiconductor elements 3 and the terminals 5 are electrically connected by means of bonding wires 4, each with a wire diameter of 0.1 mm to 0.5 mm and made of an aluminum alloy or a copper alloy. In embodiment 1, the bonding wires 4 are used.

[0027] Bonding tapes can also be used. The terminals 5 are plate-like electrodes made of copper. The terminals 5 are formed on the housing 6 by insert molding or outsert molding and are intended for a current or voltage input or output from the outside of the power module 100. The housing 6 is bonded to the base plate 1 by means of an adhesive (not shown). Generally, the housing 6 is made of a material such as PPS (polyphenylene sulfide) resin or PBT (polybutylene terephthalate) resin.

[0028] The silicone gel 8 fills the area surrounded by the housing 6 and the base plate 1 to ensure the insulating properties within the power module 100. The silicone gel 8 fills the area to a level at which the power semiconductor elements 3 and the bonding wires 4 are completely immersed in the silicone gel 8.

[0029] The pressure plate 9 is in close contact with an upper surface of the filled silicone gel 8. Furthermore, the cover 7 is arranged on an upper region of the housing 6. The cover 7 separates the interior of the power module 100 from the exterior to prevent dust and the like from entering the power module 100. The cover 7 is attached to the housing 6 by means of an adhesive (not shown) or by means of screws (not shown). It should be noted that the upper surface of the silicone gel 8 here refers to the surface of the silicone gel 8 opposite its surface in contact with the surface of the insulating substrate 2.

[0030] Fig. Figure 2 is a schematic cross-sectional view of the structure of the power module according to embodiment 1 of the present invention, the temperature of which is low. Fig. Figure 3 is a schematic cross-sectional view of the structure of the power module according to embodiment 1 of the present invention, the temperature of which is high. Fig. Figure 2 is a schematic cross-sectional view of the internal structure of module 100 when the temperature of the module is normal temperature or lower. Fig. Figure 3 is a schematic cross-sectional view of the internal structure of module 100 when the temperature of module 100 is the curing temperature of silicone gel 8 or higher.

[0031] The curing temperature of the silicone gel 8, used for the insulating seal of the power module, is typically 60°C to 80°C. The coefficient of linear expansion of the silicone gel 8 used for the insulating seal of the power module is typically 300 to 400 ppm / K. In contrast, the coefficient of linear expansion of the other components used in the power module 100 is 3 to 25 ppm / K. This means that the coefficient of linear expansion of the silicone gel 8 is several tens to hundreds of times greater than that of the other components used in the power module 100.

[0032] When the temperature of the power module 100 drops to normal temperature after the sealing process for curing the silicone gel 8, with which the housing 6 has been filled, is complete, the silicone gel 8 therefore shrinks more than other components. At this point, the surface level of the silicone gel 8 is lower than when it is cured (see Fig. 1).

[0033] As in Fig. As shown in Figure 2, the following applies: If the temperature of the power module becomes 100 lower than the normal temperature, the surface level of the silicone gel 8 will become even lower.

[0034] If, in turn, the temperature of the power module becomes 100 higher than the curing temperature, the silicone gel 8 expands thermally more than other components, so that the surface level of the silicone gel 8, as in Fig. As shown in section 3, it will be higher than the position when it has hardened.

[0035] Let ΔL be the value of the change in height of the silicone gel 8 due to the temperature change, S the surface area of ​​the silicone gel 8, V the volume of the silicone gel 8, β the volume-expansion ratio of the silicone gel 8, and ΔT the value of the temperature change. Then the ratio ΔL = V × β × ΔT × 1 / S holds.

[0036] If the gap between the lid 7 and the surface of the silicone gel 8 on the side of the lid 7 is made smaller than ΔL, the pressure plate 9 will reach the lid 7 during operation in which the power module 100 is operated at a temperature higher than the curing temperature, so that the internal stress on the silicone gel 8 becomes a pressure stress. Therefore, the gap (the distance) between the lid 7 and the pressure plate 9 must be smaller than ΔL. For example, ΔL is set so that the pressure plate 9 reaches the lid 7 when the operating temperature of the power module 100 is 150 °C or higher.

[0037] The following is a more specific example: In a power module 100, in which silicone gel 8 is used, whose curing temperature is 60 °C, whose linear coefficient of expansion is 400 ppm / K, and whose height is 10 mm, V / S = 10 mm and β = 3 × 400 ppm / K are given. For the internal stress on the silicone gel 8 to become a pressure stress when the temperature of the power module is higher than 150 °C, it is sufficient that the gap between the surface of the silicone gel 8 on the side of the cover 7 and the cover 7 is of the following relation: ΔL ≤ (10 mm) × (400 × 10 -6 K -1 ) × ((150 - 60) °C) = 1.08 mm is sufficient.

[0038] The following applies to the power module 100 described above: When the temperature of the power module 100 decreases, the pressure plate 9 is pulled downwards towards the base plate 1 due to the thermal shrinkage of the silicone gel 8. At this time, the following applies: Because it is not attached to either the housing 6 or the cover 7, the pressure plate 9 can curve in a convex shape towards the bottom (the side of the base plate 1) according to the thermal shrinkage of the silicone gel 8.

[0039] As a result, the silicone gel 8 generates virtually no thermal stress, preventing the internal stress of the silicone gel 8 from becoming a tensile stress. Even if the temperature of the power module 100 drops below this level, the growth of bubbles and delamination can be inhibited, thus preventing the insulating substrate 2 from separating from the silicone gel 8 and consequently preventing any deterioration of the power module's insulation.

[0040] When the temperature of the power module 100 increases, the pressure plate 9 is pushed upwards towards the cover 7 by the thermal expansion of the silicone gel 8. In this situation, the following applies: When the pressure plate 9 is pushed upwards so that it touches the cover 7, the cover 7 is attached to the housing 6, preventing the pressure plate 9 from moving further towards the cover 7, thus fixing its position. In this state, the silicone gel 8 can no longer expand thermally, and the internal stress on the silicone gel 8 becomes a pressure stress.

[0041] Since the internal stress on the silicone gel 8 becomes a pressure stress, the following applies: Even if the temperature of the power module 100 increases, the growth of bubbles and detachments can be prevented, thus preventing the insulating substrate 2 from detaching from the silicone gel 8. As a result, deterioration of the insulation of the power module is prevented.

[0042] It is desirable that the press plate 9 is smaller than the lid 7 in the housing 6, and that, according to the transformation of the silicone gel 8 as a result of a temperature change, the press plate is transformable (curvable) in the upward-downward direction in the sectional view of the housing 6, and that it has a size that allows it to move itself in the upward-downward direction.

[0043] In the Power Module 100, configured as described above, the pressure plate is positioned between the sealing resin and the cover, ensuring close contact with the resin. This prevents the growth of bubbles and delamination caused by stress changes resulting from the expansion and contraction of the sealing resin due to temperature fluctuations within the Power Module 100. Consequently, separation between the sealing resin and the insulating substrate is prevented, leading to improved insulation reliability of the Power Module. Design 2

[0044] Embodiment 2 differs from embodiment 1 in that projections 10 are formed on the surface of the cover 7 facing the pressure plate 9. Even with the projections 10 on the surface of the cover 7 facing the pressure plate 9, it is still possible to prevent the growth of blisters and delamination caused by changes in stress due to the expansion and contraction of the sealing resin. As a result, delamination between the sealing resin and the insulating substrate can be prevented, leading to an improvement in the insulation reliability of the power module.

[0045] Fig. Figure 4 is a schematic cross-sectional view of the structure of a power module according to embodiment 2 of the present invention. As shown in Fig. As shown in Figure 4, the power module 200 comprises the following: a base plate 1, an insulating substrate 2, power semiconductor elements 3, each functioning as a semiconductor element, bonding wires 4, terminals 5, a housing 6, which functions as a housing element, a cover 7, which functions as a cover element, silicone gel 8, which is a sealing resin, a press plate 9, projections 10, which are the first projections, and solder 11 and 12.

[0046] The pressure plate 9 is in close contact with an upper surface of the silicone gel 8. Furthermore, the lid 7 is arranged on an upper area of ​​the housing 6. The lid 7 is attached to the housing 6 by means of an adhesive (not shown) or by means of screws (not shown).

[0047] The several projections 10 are formed on the surface of the lid 7 that faces the press plate 9, so that they protrude in the direction of the press plate 9.

[0048] The configuration of the remaining components is the same as in embodiment 1.

[0049] Fig. Figure 5 is a schematic cross-sectional view of the structure of the power module according to embodiment 2 of the present invention, the temperature of which is low. Fig. Figure 6 is a schematic cross-sectional view of the structure of the power module according to embodiment 2 of the present invention, the temperature of which is high. More precisely: Fig. Figure 5 is a schematic cross-sectional view of the internal structure of module 200, whose temperature is lower than normal temperature. Fig. Figure 6 is a schematic cross-sectional view of the internal structure of module 200, whose temperature is higher than the curing temperature of the silicone gel 8.

[0050] The curing temperature of the silicone gel 8, used for the insulating seal of the power module, is typically 60°C to 80°C. The coefficient of linear expansion of the silicone gel 8 used for the insulating seal of the power module is typically 300 to 400 ppm / K. In contrast, the coefficient of linear expansion of the other components used in the power module 200 is 3 to 25 ppm / K. This means that the coefficient of linear expansion of the silicone gel 8 is several tens to several hundred times greater than that of the other components used in the power module 200.

[0051] When the temperature of the power module 200 drops to normal temperature after the silicone gel 8, with which the housing 6 has been filled, has cured to complete the sealing process, the silicone gel 8 shrinks more than other components. At this time, the surface level of the silicone gel 8 is lower than when it is cured.

[0052] As in Fig. As shown in Figure 5, the following applies: If the temperature of the power module 200 becomes lower than the normal temperature, the surface level of the silicone gel 8 will become even lower.

[0053] If, in turn, the temperature of the power module 200 becomes higher than the curing temperature, the silicone gel 8 expands thermally more than other components, so that the surface level of the silicone gel 8, as in Fig. As shown in section 6, it will be higher than the position when it has hardened.

[0054] The following applies to the power module 200 described above: When the temperature of the power module 200 decreases, the pressure plate 9 is pulled downwards towards the base plate 1 due to the thermal shrinkage of the silicone gel 8. At this time, the following applies: Because it is not attached to either the housing 6 or the cover 7, the pressure plate 9 can curve in a convex shape towards the bottom (the side of the base plate 1) according to the thermal shrinkage of the silicone gel 8.

[0055] As a result, the silicone gel 8 generates virtually no thermal stress, preventing the internal stress of the silicone gel 8 from becoming a tensile stress. Even if the temperature of the power module 200 decreases, the growth of bubbles and delamination can be inhibited, thus preventing the insulating substrate 2 from separating from the silicone gel 8 and consequently preventing any deterioration of the insulation of the power module.

[0056] When the temperature of the power module 200 increases, the pressure plate 9 is pushed upwards towards the cover 7 by the thermal expansion of the silicone gel 8. In this situation, the following applies: When the pressure plate 9 is pushed upwards so that it touches the projections 10 formed on the cover 7, the pressure plate 9 cannot move further towards the cover 7 because the cover 7 is attached to the housing 6, thus fixing the position of the pressure plate 9 there.

[0057] In this state, the silicone gel 8 can no longer expand thermally, and the internal stress of the silicone gel 8 becomes a pressure stress. Since the internal stress of the silicone gel 8 becomes a pressure stress, the following applies: Even if the temperature of the power module 200 increases, the growth of bubbles and detachments can be prevented, thus preventing the insulating substrate 2 from separating from the silicone gel 8. As a result, a deterioration of the insulation of the power module is prevented.

[0058] Fig. Figure 7 is a schematic top view of the structure of the cover of the power module according to embodiment 2 of the present invention. Fig. 7 is a projection 10 formed on the surface of the lid 7 which faces the press plate 9 in module 200. Fig. Figure 8 is a schematic top view of the structure of a further cover of the power module according to embodiment 2 of the present invention. Fig. Figure 9 is a schematic top view of the structure of a further cover of the power module according to embodiment 2 of the present invention.

[0059] Fig. Figure 10 is a schematic top view of the structure of a further cover of the power module according to embodiment 2 of the present invention. Fig. Figure 11 is a schematic top view of the structure of a further cover of the power module according to embodiment 2 of the present invention. Fig. Figure 12 is a schematic top view of the structure of a further cover of the power module according to embodiment 2 of the present invention. Fig. Figure 13 is a schematic top view of the structure of a further cover of the power module according to embodiment 2 of the present invention.

[0060] As in the Fig. As shown in Figures 7 to 13, the projection 10 or projections 10 are formed on the surface of the cover 7 that faces the pressure plate 9 in module 200. In the Fig. The shapes of the projections 10 formed on the lid 7 are different in sections 7 to 13. The projections 10 that are in Fig. 7, Fig. 10 and Fig. Figures 11 are shown in a lattice structure. The projection 10, which is in Fig. Figure 7 is formed as a combination of several stripes. The projection 10, which is in Fig. Figure 10 is formed in a cross shape.

[0061] The lead of 10, which in Fig. The projection 10 shown in Figure 11 is formed in a shape that extends radially from the center of the lid 7. Fig. 8, Fig. 12 and Fig. The 13 projections shown are formed in a dot pattern. Each of the 10 projections shown in Fig. Figure 8 is rectangular. Each of the protrusions 10, which are shown in Fig. 12 and Fig. The 13 shown are a circle. The lead is 10 in Fig. 9 has a honeycomb structure with hexagons.

[0062] In the cutaway structure of the performance module 200, which is in Fig. As shown in Figure 4, several projections 10 are formed. However, the number of projections 10 can also be one if a single projection 10 can prevent the pressure plate 9 from moving upwards. A pressure plate 9 with a large flat surface and a small thickness tends to have low stiffness, so the pressure plate 9 can easily warp when pressed against the projection 10. The warped pressure plate 9 has a lower compressive effect, and consequently, the silicone gel 8 is subjected to lower compressive loads.

[0063] In such a case, a formation of several projections 10 with narrower intervals between them, as in Fig. Figures 7 to 13 show how warping of the pressure plate 9 is prevented when it is pressed against the projections 10. The number of projections 10 and their spacing are appropriately determined so that warping of the pressure plate 9 does not pose a problem.

[0064] Even if the fill level of the silicone gel 8 varies, the projections 10 formed on the lid 7 come into contact with the pressure plate 9, allowing the silicone gel 8 to be pressed evenly. The projections 10 on the lid 7 improve its rigidity, thus preventing warping.

[0065] The projections 10 can assume any shape, provided that when pressed against the projections 10, the press plate 9 neither moves nor warps.

[0066] The projections 10 can be formed integrally with the cover 7, or the projections 10 can be formed as separate components, so that they are arranged at positions on the cover 7 that do not pose a warping or distortion problem in the press plate 9.

[0067] In the Power Module 200, configured as described above, the pressure plate is positioned between the sealing resin and the cover, ensuring close contact with the resin. This prevents the growth of bubbles and delamination caused by stress changes resulting from the expansion and contraction of the sealing resin due to temperature fluctuations within the Power Module 200. Consequently, separation between the sealing resin and the insulating substrate is prevented, leading to improved insulation reliability of the Power Module.

[0068] Even if the fill level of the silicone gel 8 in the housing 6 is not uniform, the formation of the protrusions 10 on the lid 7 can prevent partial contact of the pressure plate 9, so that a uniform pressure load against the silicone gel 8 is generated.

[0069] Furthermore, forming the projections 10 into burr shapes on the lid 7 can prevent the lid 7 from bending in order to improve its stiffness. embodiment 3

[0070] Embodiment 3 differs from embodiment 2 in that the projections 10, which in embodiment 2 are formed on the cover 7, are formed on the surface of the pressure plate 9 facing the cover 7. Even if the projections 13 are formed on the surface of the pressure plate 9 facing the cover 7, it is still possible to prevent the growth of bubbles and delamination caused by changes in load due to the expansion and contraction of the sealing resin. As a result, delamination between the sealing resin and the insulating substrate can be prevented, leading to an improvement in the insulation reliability of the power module.

[0071] Fig. Figure 14 is a schematic cross-sectional view of the structure of a power module according to embodiment 3 of the present invention. As shown in Fig. As shown in Figure 14, the power module 300 comprises: a base plate 1, an insulating substrate 2, power semiconductor elements 3, each functioning as a semiconductor element, bonding wires 4, terminals 5, a housing 6, which functions as a housing element, a cover 7, which functions as a cover element, silicone gel 8, which is a sealing resin, a press plate 9, projections 13, which are secondary projections, and solder 11 and 12.

[0072] The pressure plate 9 is in close contact with an upper surface of the silicone gel 8. Furthermore, the lid 7 is arranged on an upper area of ​​the housing 6. The lid 7 is attached to the housing 6 by means of an adhesive (not shown) or by means of screws (not shown).

[0073] The multiple projections 13 are formed on the top of the press plate 9, so that they protrude towards the lid 7.

[0074] The configuration of the remaining components is the same as in embodiment 1.

[0075] The following applies to the power module 300 described above: If the temperature of the power module 300 decreases, the pressure plate 9 is pulled downwards towards the base plate 1 due to the thermal shrinkage of the silicone gel 8. At this time, the following applies: Because it is not attached to either the housing 6 or the cover 7, the pressure plate 9 can curve in a convex shape towards the bottom (the side of the base plate 1) according to the thermal shrinkage of the silicone gel 8.

[0076] As a result, the silicone gel 8 generates virtually no thermal stress, preventing the internal stress of the silicone gel 8 from becoming a tensile stress. Even if the temperature of the power module 300 drops below this level, the growth of bubbles and delamination can be inhibited, thus preventing the insulating substrate 2 from separating from the silicone gel 8 and consequently preventing any deterioration of the power module's insulation.

[0077] When the temperature of the power module 300 increases, the pressure plate 9 is pushed upwards towards the cover 7 by the thermal expansion of the silicone gel 8. In this situation, the following applies: When the pressure plate 9 is pushed upwards until the projections 13 formed on the pressure plate 9 touch the cover 7, the pressure plate 9 cannot move further towards the cover 7 because the cover 7 is attached to the housing 6, thus fixing its position. In this state, the silicone gel 8 can no longer expand thermally, and the internal stress on the silicone gel 8 becomes a pressure stress.

[0078] Since the internal stress on the silicone gel 8 becomes a pressure stress, the following applies: Even if the temperature of the power module 300 increases, the growth of bubbles and detachments can be prevented, thus preventing the insulating substrate 2 from separating from the silicone gel 8. As a result, deterioration of the insulation of the power module is prevented.

[0079] Fig. Figure 15 is a schematic top view of the structure of a press plate of the power module according to embodiment 3 of the present invention. Fig. Figure 16 is a schematic top view of the structure of another press plate of the power module according to embodiment 3 of the present invention. The shapes of the projections 13, which are arranged on the press plates 9, differ between Fig. 15 and Fig. 16.

[0080] In embodiment 3, several projections 13 are formed. However, the number of projections 13 can also be one if a single projection 13 can prevent the press plate 9 from moving upwards. The number of projections 13 and their intervals are suitably determined so that warping of the press plate 9 does not pose a problem.

[0081] The projections 13 can assume any shape, provided that when the projections 13 are pressed against the cover 7, the pressure plate 9 neither moves nor warps. Even if the projections 13 are formed in the same shapes as those used for the projections 10 of the cover 7 shown in embodiment 2, the same effect can be achieved compared with the projections 13 shown in Fig. 15 and Fig. 16 are shown.

[0082] If the number of protrusions 13 is increased and the area given to them is enlarged, the stiffness of the press plate 9 can be increased to prevent warping of the press plate 9. Even if the temperature of the power module 300 increases, the growth of blisters and delamination can therefore be prevented to prevent deterioration of the insulation of the power module.

[0083] The projections 13 can be formed integrally with the press plate 9, or the projections 13 can be formed as separate components, so that they are arranged in positions that do not pose a distortion problem of the press plate 9.

[0084] In the Power Module 300, configured as described above, the pressure plate is positioned between the sealing resin and the cover, ensuring close contact with the resin. This prevents the growth of bubbles and delamination caused by stress changes resulting from the expansion and contraction of the sealing resin due to temperature fluctuations within the Power Module 300. Consequently, separation between the sealing resin and the insulating substrate is prevented, leading to improved insulation reliability of the Power Module.

[0085] Even if the fill level of the silicone gel 8 in the housing 6 is not uniform, the formation of the protrusions 13 on the pressure plate 9 can prevent partial contact of the pressure plate 9 with the lid 7, so that a uniform pressure load against the silicone gel 8 is generated.

[0086] Furthermore, the formation of the projections 13 in rib form on the press plate 9 can prevent bending of the press plate 9 in order to improve its stiffness. Design 4

[0087] Embodiment 4 differs from embodiments 2 or 3 in that the projections, which in embodiments 2 and 3 are formed either on the cover 7 or on the pressure plate 9, are formed on both the cover 7 and the pressure plate 9, and in positions facing each other. Even if the projections 13 are formed on the surface of the pressure plate 9 facing the cover 7, it is still possible to prevent the growth of bubbles and delamination caused by changes in load due to the expansion and contraction of the sealing resin. As a result, delamination between the sealing resin and the insulating substrate can be prevented, leading to an improvement in the insulation reliability of the power module.

[0088] Fig. Figure 17 is a schematic cross-sectional view of the structure of a power module according to embodiment 4 of the present invention. As shown in Fig. As shown in Figure 17, a power module 400 comprises the following: a base plate 1, an insulating substrate 2, power semiconductor elements 3, each functioning as a semiconductor element, bonding wires 4, terminals 5, a housing 6, which functions as a housing element, a cover 7, which functions as a cover element, silicone gel 8, which is a sealing resin, a press plate 9, projections 10, which are first projections, solder 11 and 12, and projections 13, which are second projections.

[0089] Fig. Figure 18 is a schematic cross-sectional view of the structure of a further cover and a further press plate of the power module according to embodiment 4 of the present invention. As in Fig. As shown in Figure 18, a projection 10 is formed on the surface of the cover 7, which faces the pressure plate 9 in module 400. Likewise, a projection 13 is formed on the surface of the pressure plate 9, which faces the cover 7. Fig. Figure 19 is a schematic cross-sectional view of the structure of a further cover and a further press plate of the power module according to embodiment 4 of the present invention.

[0090] Fig. Figure 20 is a schematic cross-sectional view of the structure of a further cover and a further pressure plate of the power module according to embodiment 4 of the present invention. The shapes of the projections 10 and 13 formed on the covers 7 and the pressure plate 9 differ between the Fig. 18 and Fig. 20. Any combination of the lids 7 and the press plates 9 in Fig. 18, Fig. 19 and Fig. 20 is possible as long as the projections 10 and the projections 13 are arranged at the positions where the projections 13 face the respective projections 10.

[0091] The pressure plate 9 is in close contact with an upper surface of the silicone gel 8. Furthermore, the lid 7 is arranged on an upper area of ​​the housing 6. The lid 7 is attached to the housing by means of an adhesive (not shown) or by means of screws (not shown).

[0092] The multiple projections 13 are formed on the upper side of the pressure plate 9, such that they project towards the cover 7. Furthermore, the multiple projections 10 are formed on the lower side of the cover 7 at the positions where they face the respective multiple projections 13 formed on the pressure plate 9.

[0093] The configuration of the remaining components is the same as in embodiment 1.

[0094] The following applies to the power module 400 described above: When the temperature of the power module 400 decreases, the pressure plate 9 is pulled downwards towards the base plate 1 due to the thermal shrinkage of the silicone gel 8. At this time, the following applies: Because it is not attached to either the housing 6 or the cover 7, the pressure plate 9 can curve in a convex shape towards the bottom (the side of the base plate 1) according to the thermal shrinkage of the silicone gel 8.

[0095] As a result, the silicone gel 8 generates virtually no thermal stress, preventing the internal stress of the silicone gel 8 from becoming a tensile stress. Even if the temperature of the power module 400 drops, the growth of bubbles and delamination can be inhibited, thus preventing the insulating substrate 2 from separating from the silicone gel 8 and consequently preventing any deterioration of the insulation of the power module.

[0096] When the temperature of the power module 400 increases, the pressure plate 9 is pushed upwards towards the cover 7 by the thermal expansion of the silicone gel 8. In this situation, the following applies: When the pressure plate 9 is pushed upwards until it touches the projections 10 formed on the cover 7, the pressure plate 9 cannot move further towards the cover 7 because the cover 7 is attached to the housing 6, thus fixing its position there.

[0097] In this state, the silicone gel 8 can no longer expand thermally, and the internal stress of the silicone gel 8 becomes a pressure stress. Since the internal stress of the silicone gel 8 becomes a pressure stress, the following applies: Even if the temperature of the power module 400 increases, the growth of bubbles and detachments can be prevented, thus preventing the insulating substrate 2 from separating from the silicone gel 8. As a result, a deterioration of the insulation of the power module is prevented.

[0098] In embodiment 4, several projections 10 and 13 are formed. However, the respective number of projections 10 and 13 can also be one if only a single set of a single projection 13 and a single projection 10 can prevent the press plate 9 from moving upwards. The number of projections 10 and 13, as well as the intervals between them, are suitably determined so that warping of the press plate 9 does not pose a problem. The projections 10 and 13 can assume any desired shape, provided that when the projections 10 are pressed against the projections 13, the press plate 9 neither moves nor warps.

[0099] If the sizes of the projections 10 and the projections 13 are different from each other, this can take into account the case in which a positional deviation between the projections 10 and the projections 13 is generated when the press plate 9 moves upwards towards the lid 7 as a result of the thermal expansion of the silicone gel 8.

[0100] If the number of protrusions 13 is increased and the area given to them is enlarged, the stiffness of the press plate 9 can be increased to prevent warping of the press plate 9. Therefore, even if the temperature of the power module 400 increases, the growth of blisters and delamination can be prevented to prevent deterioration of the insulation of the power module.

[0101] The projections 10 can be formed integrally with the cover 7, or the projections 10 can be formed as separate components so that they are arranged in positions that do not pose a distortion problem of the press plate 9.

[0102] Likewise, the projections 13 can be formed integrally with the press plate 9, or the projections 13 can be formed as individual components, so that they are arranged in positions that do not pose a distortion problem of the press plate 9.

[0103] In the Power Module 400, configured as described above, the pressure plate is positioned between the sealing resin and the cover, ensuring close contact with the resin. This prevents the growth of bubbles and delamination caused by stress changes resulting from the expansion and contraction of the sealing resin due to temperature fluctuations within the Power Module 400. Consequently, separation between the sealing resin and the insulating substrate is prevented, leading to improved insulation reliability of the Power Module.

[0104] Even if the fill level of the silicone gel 8 in the housing 6 is not uniform, the formation of the protrusions 10 on the lid 7 and the formation of the protrusions 13 on the pressure plate 9 can prevent partial contact of the pressure plate 9 with the lid 7, so that a uniform pressure load against the silicone gel 8 is generated.

[0105] Furthermore, forming the projections 10 in rib form on the cover 7 can prevent bending of the cover 7, thus improving its rigidity. Additionally, forming the projections 13 in burr forms on the press plate 9 can prevent bending of the press plate 9, thus improving its rigidity. Design 5

[0106] Embodiment 5 differs from embodiment 2 in that several pressure plates 9 are arranged on the silicone gel 8, whereas in embodiment 2 a single pressure plate 9 is arranged on it. Even in the case where the multiple pressure plates 9 are formed and the projections 10 are formed on the surface of the cover 7 facing the pressure plates 9, it is still possible to prevent the growth of bubbles and delamination caused by changes in stress due to the expansion and contraction of the sealing resin. As a result, delamination between the sealing resin and the insulating substrate can be prevented, leading to an improvement in the insulation reliability of the power module.

[0107] Fig. Figure 21 is a schematic cross-sectional view of the structure of a power module according to embodiment 5 of the present invention. As shown in Fig. As shown in Figure 21, the power module 500 comprises the following: a base plate 1, an insulating substrate 2, power semiconductor elements 3, each functioning as a semiconductor element, bonding wires 4, terminals 5, a housing 6, which functions as a housing element, a cover 7, which functions as a cover element, silicone gel 8, which is a sealing resin, press plates 9, projections 10, which are the first projections, and solder 11 and 12.

[0108] The multiple pressure plates 9 are arranged in close contact with an upper surface of the silicone gel 8. The pressure plates 9, consisting of several segments, are arranged such that they correspond, via the silicone gel 8, to the wiring patterns formed on a metal plate 22 on the insulating substrate 2. The cover 7 is located on an upper region of the housing 6. The cover 7 is attached to the housing by means of an adhesive (not shown) or by means of screws (not shown). The projections 10 are formed on the cover 7 at the positions corresponding to the respective multiple pressure plates 9.

[0109] The configuration of the remaining components is the same as in embodiment 1.

[0110] The following applies to the power module 500 described above: When the temperature of the power module 500 decreases, the pressure plates 9 are pulled downwards towards the base plate 1 due to the thermal shrinkage of the silicone gel 8. At this time, the following applies: Because they are not attached to either the housing 6 or the cover 7, the pressure plates 9 can curve in a convex shape towards the bottom (the side of the base plate 1) according to the thermal shrinkage of the silicone gel 8.

[0111] As a result, the silicone gel 8 generates virtually no thermal stress, which prevents the internal stress of the silicone gel 8 from becoming a tensile stress. Even if the temperature of the power module 500 drops below this level, the growth of bubbles and delamination can be inhibited, thus preventing the insulating substrate 2 from separating from the silicone gel 8 and consequently preventing any deterioration of the insulation of the power module.

[0112] When the temperature of the power module 500 increases, the pressure plate 9 is pushed upwards towards the cover 7 by the thermal expansion of the silicone gel 8. In this situation, the following applies: When the pressure plates 9 are pushed upwards so that they contact the projections 10 formed on the cover 7, the cover 7 is attached to the housing 6, preventing the pressure plates 9 from moving further towards the cover 7, thus fixing their positions. In this state, the silicone gel 8 can no longer expand thermally, and the internal stress on the silicone gel 8 becomes a pressure stress.

[0113] Since the internal stress on the silicone gel 8 becomes a pressure stress, the following applies: Even if the temperature of the power module increases by 500, the growth of bubbles and detachments can be prevented, thus preventing the separation of the insulating substrate 2 from the silicone gel 8. As a result, deterioration of the insulation of the power module is prevented.

[0114] Fig. Figure 22 is a schematic cross-sectional view of the structure of a further cover and a further press plate of the power module according to embodiment 5 of the present invention. As in Fig. As shown in Figure 22, the lid 7 has the projections 10 on the side facing the multiple press plates 9 arranged in module 500, at the positions corresponding to the respective press plates 9.

[0115] In the Power Module 500, configured as described above, the pressure plates are positioned between the sealing resin and the cover, ensuring close contact with the resin. This prevents the growth of bubbles and delamination caused by stress changes resulting from the expansion and contraction of the sealing resin due to temperature fluctuations within the Power Module 500. Consequently, separation between the sealing resin and the insulating substrate is prevented, leading to improved insulation reliability of the Power Module.

[0116] Even if the fill level of the silicone gel 8 in the housing 6 is not uniform, the formation of the protrusions 10 on the lid 7 can prevent partial contact of the pressure plates 9, so that a uniform pressure load against the silicone gel 8 is generated.

[0117] Furthermore, forming the projections 10 into burr shapes on the lid 7 can prevent the lid 7 from bending in order to improve its stiffness.

[0118] The pressure load generated in the silicone gel 8 can be controlled by dividing a pressure plate 9 into several parts to position them where bubbles and detachments need to be prevented. Design 6

[0119] Embodiment 6 differs from embodiment 2 in that springs 14 are designed as replacements for the projections 10 formed on the cover 7 in embodiment 2. The springs 14, which replace the projections 10, can prevent the growth of blisters and delamination caused by changes in load due to the expansion and contraction of the sealing resin. As a result, delamination between the sealing resin and the insulating substrate can be prevented, leading to an improvement in the insulation reliability of the power module.

[0120] Fig. Figure 23 is a schematic cross-sectional view of the structure of a power module according to embodiment 6 of the present invention. As shown in Fig.As shown in Figure 23, the power module 600 comprises the following: a base plate 1, an insulating substrate 2, power semiconductor elements 3, each functioning as a semiconductor element, bonding wires 4, terminals 5, a housing 6, which functions as a housing element, a cover 7, which functions as a cover element, silicone gel 8, which is a sealing resin, a press plate 9, springs 14, which function as an elastic element, and solder 11 and 12.

[0121] The pressure plate 9 is in close contact with an upper surface of the silicone gel 8. Furthermore, the lid 7 is arranged on an upper area of ​​the housing 6. The lid 7 is attached to the housing by means of an adhesive (not shown) or by means of screws (not shown).

[0122] The multiple springs 14 are attached to the underside of the cover 7, facing the pressure plate 9. S-shaped springs are used here as springs 14.

[0123] The configuration of the remaining components is the same as in embodiment 1.

[0124] The following applies to the power module 600 described above: When the temperature of the power module 600 decreases, the pressure plate 9 is pulled downwards towards the base plate 1 due to the thermal shrinkage of the silicone gel 8. At this time, the following applies: Because it is not attached to either the housing 6 or the cover 7, the pressure plate 9 can curve in a convex shape towards the bottom (the side of the base plate 1) according to the thermal shrinkage of the silicone gel 8.

[0125] As a result, the silicone gel 8 generates virtually no thermal stress, preventing the internal stress of the silicone gel 8 from becoming a tensile stress. Even if the temperature of the power module 600 drops, the growth of bubbles and delamination can be inhibited, thus preventing the insulating substrate 2 from separating from the silicone gel 8 and consequently preventing any deterioration of the power module's insulation.

[0126] When the temperature of the power module 600 increases, the pressure plate 9 is pushed upwards towards the cover 7 by the thermal expansion of the silicone gel 8. In this situation, the following applies: When the pressure plate 9 contacts the springs 14 located on the cover 7 and is pushed upwards until the restoring force of the springs exceeds the expansion force of the gel, the pressure plate 9 cannot move further towards the cover 7 because the cover 7 is attached to the housing 6, thus fixing its position there. The silicone gel 8 can then no longer expand thermally, and the internal stress on the silicone gel 8 becomes a compressive stress.

[0127] Since the internal stress of the silicone gel 8 becomes a pressure load, the following applies: Even if the temperature of the power module 600 increases, the growth of bubbles and delamination can be prevented. As a result, a deterioration of the insulation of the power module is prevented.

[0128] In embodiment 6, several springs 14 are arranged. However, the number of springs 14 can also be one if a single spring 14 is sufficient to prevent the pressure plate 9 from moving upwards. The number of springs 14 and their spacing are suitably determined so that warping of the pressure plate 9 does not pose a problem.

[0129] Although S-shaped springs are used as springs 14 in embodiment 6, the type of spring is not limited to S-shaped springs. Another spring with a restoring force, such as a coil spring or a leaf spring, can also be used.

[0130] In embodiment 6, the springs 14 are attached to the cover 7. Alternatively, the springs 14 can also be attached to the top of the pressure plate so that they point towards the cover 7. The same effect can be achieved if the springs 14 are arranged between the cover 7 and the pressure plate 9.

[0131] In the Power Module 600, configured as described above, the pressure plate is positioned between the sealing resin and the cover, ensuring close contact with the resin. This prevents the growth of bubbles and delamination caused by stress changes resulting from the expansion and contraction of the sealing resin due to temperature fluctuations within the Power Module 600. Consequently, separation between the sealing resin and the insulating substrate is prevented, leading to improved insulation reliability of the Power Module.

[0132] Since the springs 14 are arranged on the lid 7, a uniform pressure load against the silicone gel 8 can be generated by means of the elasticity of the springs 14. Model 7

[0133] Embodiment 7 differs from embodiments 1 to 6 in that the pressure plate 9 is a heavy object. Even with the heavy pressure plate 9, it is therefore possible to prevent the growth of blisters and delamination caused by changes in load due to the expansion and contraction of the sealing resin. As a result, delamination between the sealing resin and the insulating substrate can be prevented, leading to an improvement in the insulation reliability of the power module.

[0134] The heavy press plate 9 is made of copper or a copper alloy. The configuration of the other components is the same as in embodiment 1.

[0135] In this configuration, the downward pressure force constantly exerted on the upper surface of the silicone gel 8 by the heavy pressure plate 9 further increases the internal pressure load of the silicone gel 8. Even if the temperature of the power module 100 increases, the generation of pressure load in the silicone gel 8 continues, thus preventing the growth of bubbles and detachments and preventing the insulating substrate 2 from separating from the silicone gel 8. As a result, deterioration of the power module's insulation is prevented.

[0136] It should be noted that a heavy object here is an object (a pressure plate 9) made of a suitable quality material which, when placed on the upper surface of the silicone gel 8, can exert a pressure load in the silicone gel 8 towards the insulating substrate 2 with its own weight.

[0137] The press plate 9 described above is made of copper or a copper alloy. However, the material is not limited to this. Materials with a higher density than the silicone gel 8 can be used. Metals such as aluminum, an aluminum alloy, iron, or an iron alloy are suitable. A composite element made of these metals, or of these metals and a resin, can also be used.

[0138] In the Power Module 100, configured as described above, the heavy pressure plate is positioned between the sealing resin and the cover, ensuring close contact with the resin. This prevents the growth of bubbles and delamination caused by stress changes resulting from the expansion and contraction of the sealing resin due to temperature fluctuations within the Power Module 100. Consequently, separation between the sealing resin and the insulating substrate is prevented, leading to improved insulation reliability of the Power Module.

[0139] Even if the heavy press plate is applied to any structure of the power modules 200, 300, 400, 500 and 600, the same effect can be achieved. Description of the reference symbols 1 Base plate 2 Insulating substrate 3 Power semiconductor element 4 bonding wire 5 connection 6 cases 7 lids 8 silicone gel 9 Press plate 10 lead 13 lead 11 Lot 12 Lot 14 springs 21 Insulating layer 22 metal plate 23 metal plates 100 power module 200 power module 300 power module 400 power module 500 power module 600 power module

Claims

[1] Power module (100) comprising the following: - an insulating substrate (2) on the first surface of which a semiconductor element (3) is formed; - a base plate (1) connected to a second surface of the insulating substrate (2); - a housing element (6) that surrounds the insulating substrate (2) and is in contact with a surface of the base plate (1) that is connected to the second surface of the insulating substrate (2); - a sealing resin (8) that fills an area surrounded by the base plate (1) and the housing element (6) to seal the insulating substrate (2); - a pressure plate (9) which is arranged in close contact with an opposite surface of the sealing resin (8) with respect to the first surface of the insulating substrate (2); and - a cover element (7) which faces an opposite surface of the pressure plate (9) with respect to its surface in close contact with the sealing resin (8), and which is attached to the housing element (6) in a position which prevents the pressure plate (9) from moving further upwards towards the cover element (7) when it touches the cover element (7), wherein there is a gap between the cover element (7) and a surface of the sealing resin (8) at normal temperature, and wherein a change in height of the sealing resin (8) at an operating temperature of the power module (100) of 150°C corresponds to this gap, and wherein when the operating temperature of the power module (100) is 150°C or higher, the pressure plate (9) reaches the cover element (7). [2] Power module (100) according to claim 1, wherein the cover element (7) has a first projection (10) on its surface opposite the press plate (9). [3] Power module (100) according to claim 1 or 2, wherein the press plate (9) has a second projection (13) on its surface opposite the cover element (7). [4] Power module (100) according to claim 2, wherein the press plate (9) has a second projection (13) on its surface opposite the cover element (7), and wherein the second projection (13) and the first projection (10) are arranged opposite each other. [5] Power module (100) according to claim 2, wherein the first projection (10) is a spring. [6] Power module (100) according to one of claims 1 to 5, wherein the press plate (9) is a heavy object.

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