Power semiconductor mounting structure

Abstract

To provide a power semiconductor mounting structure capable of suppressing temperature rise and achieving high output.SOLUTION: A component is produced with a cell stud attached to a heat sink, mounting holes are provided in a power semiconductor and a substrate, the power semiconductor is installed on the heat sink by inserting the cell stud into the mounting hole of the power semiconductor, the substrate is installed on the power semiconductor by inserting the cell stud into the mounting hole of the substrate, and a nut is screwed onto the cell stud protruding from the mounting hole of the substrate to secure it in place.SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] The present invention relates to a mounting structure for power semiconductors used, for example, in high-output chargers, DC / DC converters, etc., and specialized for power control and conversion, and in particular to a mounting structure devised to suppress temperature rise and achieve high output. [Background technology]

[0002] For example, there are two types of mounting structures for power semiconductors specialized for power control and conversion: insertion mounting and surface mounting. With insertion mounting, an insertion type (TO-247, etc.) power semiconductor is used, and its lead terminal is inserted into a through hole in the board and soldered. On the other hand, with surface mounting, a surface mount type (TO-263, etc.) power semiconductor is used, and its lead terminal is soldered to a pad provided on the surface of the board.

[0003] When comparing through-hole mounting and surface mounting under the condition of contacting a reference surface, through-hole mounting has the advantage of having a larger surface area and therefore lower thermal resistance, but on the other hand, it has the disadvantage of occupying a large area of ​​the board. On the other hand, surface mounting has the advantage that it can be easily mounted in a small area, which is convenient for achieving miniaturization and high density.

[0004] An example of a power semiconductor of an insertion mount type (TO-247, etc.) mounted on a board is shown in Fig. 19. As shown in Fig. 19(a), a power semiconductor 101 is arranged vertically on a board (not shown). A plurality of (e.g., three) lead terminals 103 are taken out from the power semiconductor 101, and these lead terminals 103 are inserted into through holes (not shown) provided in the board and soldered. The power semiconductor 101 is fixed to a heat sink 107 by a screw member 109 via a heat dissipation sheet 105.

[0005] The mounting structure shown in Fig. 19(b) is roughly the same as the mounting structure shown in Fig. 19(a), but differs in that no heat dissipation sheet 105 is interposed between the power semiconductor 101 and the heat sink 107. This is easily applicable when the power semiconductor 101 is fully molded.

[0006] Also, as shown in Fig. 20, an insertion mount type (TO-247, etc.) power semiconductor 101 may be attached in a surface mount manner. Fig. 21 shows a state where a substrate 111 is placed on a plurality of power semiconductors 101 shown in Fig. 20. Lead terminals 103 taken out from the power semiconductor 101 are inserted into through holes in the substrate 111 and soldered.

[0007] On the other hand, when a surface mount type (TO-263, etc.) power semiconductor 113 is selected, the mounting structure is as shown in FIG. 22, for example. First, the power semiconductor 113 is mounted on a substrate 115. Lead terminals 117 taken out from the power semiconductor 113 are soldered to pads (not shown) on the surface of the substrate 115. The substrate 115 is provided with thermal vias (through holes) (not shown). The substrate 115 is placed on a mounting base 123 of a heat sink 121 via a soft heat dissipation sheet 119. The base end of the lead terminal 117 serves as a heat generation center 125. FIG. 23 is a perspective view of the power semiconductor 113 and the substrate 115 in FIG. 22, viewed obliquely from above.

[0008] FIG. 24 shows an example in which a surface mount type (TO-263 or the like) power semiconductor 113 is mounted between a substrate 115 and a soft heat dissipation sheet 119. FIG. 25 is a perspective view of the power semiconductor 113 and the heat dissipation sheet 119 in FIG. 24, viewed obliquely from below. When the thickness of the power semiconductor 113 is thin and wide, or when the thermal resistance between the junction and the case of the power semiconductor 113 (θ jc ) is low, the heat dissipation is improved.

[0009] Prior art documents disclosing mounting structures for power semiconductors include, for example, Patent Document 1 and Patent Document 2. [Prior art documents] [Patent documents]

[0010] [Patent Document 1] JP 2020-145420 A [Patent Document 2] JP 2020-124008 A Summary of the Invention [Problem to be solved by the invention]

[0011] The above conventional configuration has the following problems. First, in the mounting structure shown in FIG. 19 using an insertion-mount type (TO-247, etc.) power semiconductor 101, the power semiconductor 101 stands vertically on the substrate and is mounted on a heat sink 107, which causes problems such as loss of miniaturization and increased costs. In addition, in the case of the mounting structure shown in Figures 20 and 21 using a power semiconductor 101 of an insertion mounting type (TO-247, etc.), it becomes difficult to route the circuit pattern, and the lead terminals of the power semiconductor 101 are bent, making it difficult to insert the power semiconductor 101 into the board. Furthermore, due to poor insertion properties, there are problems such as unstable contact between the heat sink 107 and the power semiconductor 101 and stress on the power semiconductor 101 after mounting. Furthermore, the assembly process requires more man-hours and requires specialized jigs, which increases assembly costs. In the worst case, variations in assembly can lead to the problems mentioned above. Furthermore, if the contact becomes unstable, the thermal resistance increases, causing a problem of temperature rise.

[0012] Furthermore, in the conventional mounting structure shown in Figs. 22 to 25 using surface mount type (TO-263, etc.) power semiconductor 111, there are cases where the thermal resistance increases and the temperature is prone to rise. Incidentally, thermal resistance is calculated using the following formula (I). Thermal resistance = thickness / (contact area x thermal conductivity)---(I) In the case of a surface-mount type (TO-263, etc.) power semiconductor 111, the distance from the heat generation center 125 to the outside air surface (the outer surface of the heat sink 121) is long, so the "thickness" in the above formula (I) increases, resulting in an increase in thermal resistance and a rise in temperature. In addition, the small surface area results in a small contact area, which increases thermal resistance and causes a rise in temperature.

[0013] The present invention has been made based on these points, and its object is to provide a mounting structure for power semiconductors that can be finished into a small module package by combining existing power semiconductors with sheet metal processed parts using a general-purpose method without creating a dedicated module package type, thereby suppressing temperature rise and achieving high output. [Means for solving the problem]

[0014] In order to solve the above problem, the mounting structure for a power semiconductor according to claim 1 of the present invention comprises generating a component with a cell stud attached to a heat sink, providing mounting holes in a power semiconductor and a substrate having mounting holes, inserting the cell stud into the mounting hole of the power semiconductor to install the power semiconductor on the heat sink, inserting the cell stud into the mounting hole of the substrate to install the substrate on the power semiconductor, and screwing a nut onto the cell stud protruding from the mounting hole of the substrate to fix the cell stud in place. The power semiconductor mounting structure according to claim 2 is the power semiconductor mounting structure according to claim 1, characterized in that mounting holes are provided in a rubber heat dissipation sheet, the cell studs are inserted into the mounting holes in the rubber heat dissipation sheet, the rubber heat dissipation sheet is placed on the heat dissipation plate, and the power semiconductor is placed on top of the rubber heat dissipation sheet. The mounting structure for a power semiconductor according to claim 3 is characterized in that in the mounting structure for a power semiconductor according to claim 1, the part is a sheet metal part formed by pressing the cell stud made of metal into a mounting hole provided in the heat sink made of aluminum or copper. Furthermore, the power semiconductor mounting structure according to claim 4 is the power semiconductor mounting structure according to claim 1, characterized in that the heat sink is installed on a mounting base of a housing or a heat sink. Furthermore, the power semiconductor mounting structure according to claim 5 is the power semiconductor mounting structure according to claim 4, characterized in that a soft heat dissipation sheet is interposed between the heat sink and the mounting base. Further, the mounting structure for a power semiconductor according to claim 6 is characterized in that, in the mounting structure for a power semiconductor according to claim 1, the power semiconductor is an insertion-mount type power semiconductor, a lead terminal is taken out from the power semiconductor, and the lead terminal is bent and inserted into a through hole of the board. Furthermore, the power semiconductor mounting structure according to claim 7 is characterized in that, in the power semiconductor mounting structure according to claim 1, a nut seating stabilization member for suppressing loosening of the nut is interposed between the nut and the substrate. Moreover, the mounting structure for a power semiconductor according to claim 8 is the mounting structure for a power semiconductor according to claim 1, characterized in that the nut is a flanged nut. The power semiconductor mounting structure according to claim 9 is the power semiconductor mounting structure according to claim 4, characterized in that a board fixing boss is protruding from the housing or heat sink, the board is fixed to the board fixing boss with a fixing screw, and a board support member is interposed between the board and the heat sink on the outer periphery of the board fixing boss. Further, the mounting structure for a power semiconductor according to claim 10 is characterized in that, in the mounting structure for a power semiconductor according to claim 4, a board support member is interposed on the board below the nut and the fixing screw so as to straddle the nut and the fixing screw. The power semiconductor mounting structure according to claim 11 is the power semiconductor mounting structure according to claim 4, characterized in that a board fixing boss is protruding from the housing or heat sink, the board is fixed to the board fixing boss with a fixing screw, and a plurality of dummy patterns are stacked and connected via through holes so as to straddle the mounting holes of the cell studs and the mounting holes of the fixing screws on the board. The power semiconductor mounting structure according to claim 12 is characterized in that in the power semiconductor mounting structure according to claim 11, a slit-shaped through hole is provided in the substrate near the dummy pattern. The power semiconductor mounting structure according to claim 13 is characterized in that, in the power semiconductor mounting structure according to claim 1, when a space is formed between the mounting hole of the power semiconductor and the mounting hole of the board, a board support member is inserted into the space. Effect of the Invention

[0015] As described above, according to the power semiconductor mounting structure of claim 1 of the present invention, a component with a cell stud attached to a heat sink is prepared, mounting holes are provided in a power semiconductor and a board with mounting holes, the cell stud is inserted into the mounting hole of the power semiconductor to install the power semiconductor on the heat sink, the board is installed on the power semiconductor by inserting the cell stud into the mounting hole of the board, and a nut is screwed onto the cell stud protruding from the mounting hole of the board to fix them in place, so that an air gap is unlikely to form and a tightly sealed state can be obtained, thereby suppressing temperature rise. Also, the positioning of the power semiconductor and the board can be facilitated, thereby improving assembly. The power semiconductor mounting structure according to claim 2 is the power semiconductor mounting structure according to claim 1, in which mounting holes are provided in the rubber heat dissipation sheet, the cell studs are inserted into the mounting holes in the rubber heat dissipation sheet, the rubber heat dissipation sheet is placed on the heat dissipation plate, and the power semiconductor is placed on top of the rubber heat dissipation sheet, so that the heat conducted to the heat dissipation plate can be efficiently conducted to the housing or heat sink side via the rubber heat dissipation sheet. Also, low thermal resistance due to insulation and thinness is guaranteed, and heat conduction to the heat dissipation plate side is promoted. According to the power semiconductor mounting structure of claim 3, in the power semiconductor mounting structure of claim 1, the part is a sheet metal part formed by pressing a cell stud into an aluminum or copper sheet metal plate, so it has high thermal conductivity and can efficiently dissipate heat generated by the power semiconductor to the heat sink side via the rubber heat dissipation sheet. Also, because it is a sheet metal part, it is possible to reduce costs during mass production. According to the power semiconductor mounting structure of claim 4, in the power semiconductor mounting structure of claim 1, the heat sink is installed on the mounting base of the housing or heat sink, so that the heat conducted to the heat sink can be thermally conducted to the housing or heat sink side via the mounting base. According to the power semiconductor mounting structure of claim 5, since a soft heat dissipation sheet is interposed between the heat sink and the mounting base in the power semiconductor mounting structure of claim 4, the heat conducted to the heat sink can be conducted to the housing or heat sink side via the soft heat dissipation sheet. Also, the soft heat dissipation sheet is compressed to absorb tolerances and increase the degree of adhesion, thereby enhancing the above-mentioned effect. According to the power semiconductor mounting structure of claim 6, in the power semiconductor mounting structure of claim 1, the power semiconductor is an insertion-mount type power semiconductor, and lead terminals are taken out from the power semiconductor and the lead terminals are bent and inserted into the through holes of the board. Therefore, the contact area of ​​the insertion-mount type power semiconductor is larger than that of a surface-mount type power semiconductor, thereby reducing the contact thermal resistance and suppressing the temperature rise. According to the power semiconductor mounting structure of claim 7, in the power semiconductor mounting structure of claim 1, a nut seating stabilization member that suppresses loosening of the nut is interposed between the nut and the board, so that loosening of the nut can be suppressed and a strong mounting state of the power semiconductor can be maintained. According to the power semiconductor mounting structure of claim 8, in the power semiconductor mounting structure of claim 1, the nut is a flanged nut, so that loosening of the nut can be suppressed and a firm mounting state of the power semiconductor can be maintained. According to the power semiconductor mounting structure of claim 9, in the power semiconductor mounting structure of claim 4, a board fixing boss is protruded from the housing or heat sink, the board is fixed to the board fixing boss with a fixing screw, and a board support member is interposed between the board and the heat sink on the outer periphery of the board fixing boss, thereby making it possible to suppress the occurrence of distortion due to warping in the board. According to the power semiconductor mounting structure of claim 10, in the power semiconductor mounting structure of claim 4, a board support member is inserted on the board below the nut and the fixing screw so as to straddle the nut and the fixing screw, so that it is possible to suppress the occurrence of distortion due to warping in the board. Furthermore, according to the power semiconductor mounting structure of claim 11, in the power semiconductor mounting structure of claim 4, a board fixing boss is protruded from the housing or heat sink, and the board is fixed to the board fixing boss with a fixing screw, and a plurality of dummy patterns are connected via through holes and stacked on the board so as to straddle the mounting holes of the cell stud and the mounting holes of the fixing screws, thereby making it possible to suppress the occurrence of distortion due to warping in the board. Furthermore, according to the power semiconductor mounting structure of claim 12, in the power semiconductor mounting structure described in claim 11, a slit-shaped through hole is provided in the substrate near the dummy pattern, so that the occurrence of distortion due to warping in the substrate can be suppressed. Furthermore, according to the power semiconductor mounting structure of claim 13, in the power semiconductor mounting structure described in claim 1, when a space is formed between the mounting hole of the power semiconductor and the mounting hole of the board, a board support member is inserted into the space, thereby making it possible to suppress the occurrence of distortion due to warping in the board. [Brief description of the drawings]

[0016] [Figure 1] FIG. 1 is a cross-sectional view showing a mounting structure for an insertion-mount type (TO-247, etc.) power semiconductor according to a first embodiment of the present invention. [Diagram 2] FIG. 1 is a diagram showing a first embodiment of the present invention, and is a perspective view showing a mounting structure for an insertion-mount type (TO-247, etc.) power semiconductor. [Diagram 3] FIG. 1 is a diagram showing a first embodiment of the present invention, and is a perspective view showing a mounting structure for an insertion-mount type (TO-247, etc.) power semiconductor. [Figure 4] FIG. 13 is a diagram for explaining the operation of the comparative example, showing the temperature rise when a surface mount type (TO-263 or the like) power semiconductor is used. [Diagram 5] FIG. 1 illustrates the first embodiment of the present invention, and is a diagram showing a temperature rise when a through-hole mounting type (TO-247, etc.) power semiconductor is used. [Figure 6] FIG. 1 is a diagram showing a first embodiment of the present invention, illustrating the relationship between an actual device model and a thermal analysis model. [Figure 7] FIG. 1 is a diagram showing a first embodiment of the present invention, illustrating the relationship between an actual device model and a thermal analysis model. [Figure 8] FIG. 1 is a diagram showing the first embodiment of the present invention, and is a graph showing the coefficient of ON resistance of a power semiconductor. [Figure 9] FIG. 11 is a perspective view showing a mounting portion of a power semiconductor as viewed through a substrate, showing a second embodiment of the present invention. [Figure 10] FIG. 11 is a perspective view showing a mounting portion of a power semiconductor as viewed through a substrate, showing a third embodiment of the present invention. [Figure 11]FIG. 13 is a perspective view showing a mounting portion of a power semiconductor as viewed through a substrate, showing a fourth embodiment of the present invention. [Figure 12] 12A and 12B are diagrams showing a fifth embodiment of the present invention, in which FIG. 12A is a plan view of a mounting hole portion of a substrate, and FIG. 12B is a cross-sectional view taken along line bb of FIG. 12A. [Figure 13] 13A and 13B are diagrams showing a sixth embodiment of the present invention, in which FIG. 13A is a plan view of a mounting portion of a power semiconductor seen through a substrate, and FIG. 13B is a cross-sectional view taken along line bb of FIG. 13A. [Figure 14] 14A and 14B are diagrams showing a sixth embodiment of the present invention, in which FIG. 14A is a cross-sectional view of a mounting portion for a power semiconductor, and FIG. 14B is a perspective view of the mounting portion for the power semiconductor with the substrate removed. [Figure 15] 15A and 15B are diagrams showing a seventh embodiment of the present invention, in which FIG. 15A is a cross-sectional view of a mounting portion for a power semiconductor, and FIG. 15B is a perspective view showing a mounting structure for the power semiconductor. [Figure 16] 16A and 16B are diagrams showing an eighth embodiment of the present invention, in which FIG. 16A is a plan view showing a part of a substrate, and FIG. 16B is a cross-sectional view taken along line bb of FIG. 16A. [Figure 17] FIG. 13 is a diagram showing a ninth embodiment of the present invention, and is a plan view of a mounting portion for a power semiconductor as viewed through a substrate. [Figure 18] FIG. 23 is a cross-sectional view showing a mounting structure for a power semiconductor according to a tenth embodiment of the present invention. [Figure 19] These figures show conventional examples. FIG. 19(a) is a perspective view showing an attachment structure for a through-hole mounting type (TO-247, etc.) power semiconductor, and FIG. 19(b) is a perspective view showing an attachment structure for a through-hole mounting type (TO-220, etc.) power semiconductor. [Figure 20] FIG. 13 is a perspective view showing a conventional example, illustrating a structure in a state where a substrate is removed from a mounting portion of an insertion-mount type (TO-247, etc.) power semiconductor. [Figure 21] FIG. 1 is a perspective view showing a mounting structure for a insertion-mount type (TO-247, etc.) power semiconductor, according to a conventional example. [Figure 22] FIG. 1 is a cross-sectional view showing a mounting structure for a surface-mount type (TO-263, etc.) power semiconductor, showing a conventional example. [Figure 23] FIG. 1 is a perspective view showing a conventional example, illustrating an actual model of a surface mount type (TO-263, etc.) power semiconductor. [Figure 24] FIG. 1 is a cross-sectional view showing a mounting structure for a surface mount type (TO-263, etc.) power semiconductor, showing a conventional example. [Diagram 25] FIG. 1 is a perspective view showing a mounting structure for a surface mount type (TO-263, etc.) power semiconductor, showing a conventional example. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0017] A first embodiment of the present invention will be described below with reference to Figs. 1 to 8. Fig. 1 is a cross-sectional view showing a mounting structure for a power semiconductor according to this embodiment, and first there is a housing 1. A mounting base 3 is installed inside this housing 1. A heat sink 5 is installed on the mounting base 3 via a soft heat sink sheet 7. The heat sink 5 is made of a non-ferrous metal with high thermal conductivity, and a cell stud 9 is press-fitted and fixed into this heat sink 5 by a press, and is prepared in advance as a sheet metal part. Examples of the non-ferrous metal having high thermal conductivity include aluminum and copper. The material of the soft heat dissipating sheet 7 may be silicone, acrylic, or urethane.

[0018] There is a rubber heat dissipation sheet 15, which is provided with mounting holes 16. The heat dissipation sheet 15 is placed on the heat dissipation plate 5 with the cell studs 9 inserted into the mounting holes 16. There is a power semiconductor 11 of an insertion mount type (TO-247, etc.), which has a larger contact area than a surface mount type (TO-263, etc.) power semiconductor. This power semiconductor 11 is provided with a mounting hole 13. The power semiconductor 11 is placed on the rubber heat dissipation sheet 15 with the cell stud 9 inserted through the mounting hole 13.

[0019] There is a substrate 17, which is also provided with a mounting hole 19. The substrate 17 is placed on the power semiconductor 11 with the cell stud 9 inserted through the mounting hole 19. A nut 21 is screwed onto the tip of the cell stud 9 that protrudes upward from the mounting hole 19 of the substrate 17, thereby fixing the heat sink 5, heat sink sheet 15, power semiconductor 11, and substrate 17.

[0020] A lead terminal 23 is taken out from the power semiconductor 11 in a direction parallel to the substrate 17, and the lead terminal 23 is bent by 90 degrees and inserted into a through hole 25 provided in the substrate 17. The tip of the lead terminal 23 passes through the through hole 25 and protrudes upward. The part of the lead terminal 23 protruding from the through hole 25 is soldered to the substrate 17. By performing this soldering last, solder stress can be reduced. Incidentally, performing the soldering last means that after the lead terminals 23 of the power semiconductor 11 are inserted into the through holes 25 of the substrate 17, the cell studs 9 of the heat sink 5 are inserted through the mounting holes 13 and 19, and the nuts 21 are screwed on before soldering. The base end of the lead terminal 23 serves as a heat generating center portion 27 , and the heat generating center portion 27 is disposed at a position biased toward the heat sink 5 side in the power semiconductor 11 .

[0021] FIG. 2 is a perspective view of the state before the substrate 17 is placed on the power semiconductor 11, as viewed obliquely from above. FIG. 3 is a perspective view of the state after the substrate 17 is placed on the power semiconductor 11, as viewed obliquely from above.

[0022] The above configuration can provide the following functions and effects. First, the contact area of ​​the insertion-mount type (TO-247, etc.) power semiconductor 11 is larger than that of the surface-mount type (TO-263, etc.) power semiconductor, so that the contact thermal resistance is reduced and the temperature rise can be suppressed, thereby enabling higher output.

[0023] This point has been confirmed through thermal analysis, and will now be explained. The power semiconductor used in the secondary circuit of the high-power DC / DC converter is a power MOSFET made of SiC (silicon carbide), and an experimental example of thermal analysis for this is explained below. In the thermal analysis verification, the ambient temperature was 60°C, and a forced air-cooling structure was used.

[0024] Figure 4 shows verification by thermal analysis using a comparative example, showing the case where four surface-mount type (TO-263, etc.) power semiconductors are arranged side by side, with a loss of 8.3 W per semiconductor, resulting in a temperature exceeding 110°C. In contrast, FIG. 5 shows the case where three power semiconductors 11 of the insertion mounting type (TO-247, etc.) adopted in this embodiment are arranged side by side, with a loss of 18.5 W per semiconductor, resulting in a temperature of 100° C. or less.

[0025] This is because surface mount type (TO-263, etc.) power semiconductors have a small size (contact area), which increases the contact thermal resistance, and when this is combined with an increase in ON resistance, the temperature rise becomes significant, so in order to suppress this, if low loss per unit is assumed, the number will be increased, which results in a wider mounting area. In contrast, in the case of insertion mount type (TO-247, etc.) power semiconductor 11, even if the size (contact area) is large, the contact thermal resistance decreases, and when this is combined with a decrease in ON resistance, the temperature rise is difficult, so even if the loss per unit is high, the number does not increase and the mounting area becomes narrower. The ON resistance is as shown in Fig. 8. Fig. 8 shows the change in junction temperature on the horizontal axis and ON resistance on the vertical axis. Incidentally, there was not much difference in cost between the surface mount type (TO-263, etc.) and the insertion mount type (TO-247, etc.) selected in this case, so the cost reduction effect of reducing one unit is significant.

[0026] The conditions for this thermal analysis verification are as follows: 1. The thermal conductivity of the board is defined as a constant value for the entire board, so heat is transferred more easily than with the board pattern of an actual device. 2. The effects of contact instability that occurred in the actual device are not included, and the analysis assumes contact stability. The contact surface definition in the analysis is based on boundary conditions or material properties. 3. As shown in Figs. 6 and 7, the power MOSFET model has a rectangular one-block structure, which differs from the actual device model in that the temperature difference inside the power MOSFET in the analysis is easily mitigated. 4. Losses in a power MOSFET are calculated as "current squared" x "ON resistance" (generally "I 2 There is a relationship between the on-resistance and the junction temperature (called "on-resistance coefficient" and "ratio") of the target power MOSFET, where when the junction temperature is 25°C the on-resistance is 1, and as the junction temperature rises the on-resistance increases by a specific coefficient (multiplication factor). Therefore, at the verification stage, estimates are taken into account and so temperature differences with the actual device are likely to occur. Although temperature differences with the actual device do occur in this way, the verification using thermal analysis in this case is to quantitatively judge the comparison between "surface mount type" and "insertion mount type", and does not seek absolute temperature values.

[0027] In addition, because each power semiconductor has good heat dissipation properties, there is little effect of mutual temperature interference even if the pitch of the power semiconductors 11 of the insertion mounting type (TO-247, etc.) is narrowed. In addition, since not only surface mount type (TO-263, etc.) power semiconductors but also insertion mount type (TO-247, etc.) power semiconductors 11 are available as options, the selection variations of power semiconductors are expanded. Furthermore, even if the size of the power semiconductor 11 of the insertion mounting type (TO-247, etc.) is large, only a small number of them are required, so that miniaturization can be considered. Moreover, the heat sink 5 is made of aluminum, which has a high thermal conductivity, and is made by sheet metal processing, which allows for reduction in costs during mass production.

[0028] In addition, since the distance between the heat generating center 27 and the outside air surface is short, the thermal resistance in the thickness direction is reduced, which also makes it possible to suppress the temperature rise. In addition, the power semiconductor 11 is sandwiched between the heat sink 5 and the substrate 17 and fastened by the cell stud 9 and nut 21, so that an air gap is unlikely to form and a tightly sealed state can be obtained, thereby suppressing temperature rise. Furthermore, since the power semiconductor 11 of the insertion mounting type (TO-247, etc.) is disposed on the underside of the substrate 17, the wiring loss of the circuit pattern is reduced, and as a result, the size can be reduced. In addition, the cell studs 9 are press-fitted into the heat sink 5 and then inserted into the mounting holes 13 of the power semiconductors 11 for installation, which facilitates positioning of the power semiconductors 11 and improves assembly. Moreover, the heat generated in the power semiconductor 11 is thermally conducted to the heat sink 5, whereby the heat is diffused, making it possible to suppress the occurrence of heat concentration (hot spots). In addition, since the heat sink 5 is installed on the mounting base 3 of the housing 1 via the soft heat dissipation sheet 7, the heat conducted to the heat sink 5 can be efficiently conducted to the housing 1 side via the soft heat dissipation sheet 7. Furthermore, the soft heat dissipation sheet 7 is compressed to ensure adhesion, and heat conduction to the housing 1 side is promoted. In addition, since a rubber heat dissipation sheet 15 is inserted between the power semiconductor 11 and the heat sink 5, it is necessary to ensure insulation, and a sheet as thin as possible is selected to reduce thermal resistance and promote thermal conduction to the heat sink 5 side.

[0029] Next, a second embodiment of the present invention will be described with reference to Fig. 9. In the fastening structure using the cell stud 9 and nut 21, there is a concern that loosening may occur due to vibration and thermal cycles. Therefore, in the case of the second embodiment, a board mounting earth terminal 31 is inserted between the nut 21 and the board 17. The other configurations are the same as those of the first embodiment, and the same parts in the drawings are given the same reference numerals and their explanation is omitted. By inserting the above-mentioned circuit board mounting ground terminal 31, the seating of the nut 21 can be stabilized, and the occurrence of loosening due to vibration and thermal cycles can be suppressed. If the loosening cannot be prevented, it is advisable to add a spring washer. In that case, if the length of the cell stud 9 is insufficient, change the length.

[0030] Next, a third embodiment of the present invention will be described with reference to Fig. 10. In the third embodiment, a flat washer 43 is interposed between the nut 21 and the base plate 17. The other configurations are the same as those of the first embodiment, and the same parts in the drawings are given the same reference numerals and their explanation is omitted. By inserting the flat washer 43, loosening caused by vibration and thermal cycles can be suppressed. By inserting the flat washer 43, the seating of the nut 21 can be stabilized, and loosening caused by vibration and thermal cycles can be suppressed. If the occurrence of loosening cannot be prevented, a spring washer may be added between the flat washer 43 and the nut 21. In that case, if the length of the cell stud 9 is insufficient, change the length.

[0031] Next, a fourth embodiment of the present invention will be described with reference to Fig. 11. In this fourth embodiment, the nut 21 is a flanged nut 21'. The other configurations are the same as those of the first embodiment, and the same parts in the drawings are given the same reference numerals and their explanation is omitted. By inserting the flanged nut 21' instead of the nut 21, the seating can be stabilized and loosening caused by vibration and thermal cycles can be suppressed.

[0032] Next, a fifth embodiment of the present invention will be described with reference to Fig. 12. In the fifth embodiment, ring-shaped lands 51, 53 are provided on the front and back sides around mounting hole 19 of substrate 17, and a plurality of through holes 55 are provided between these lands 51, 53. The mounting hole 19 is a non-through hole. The other configurations are the same as those of the first embodiment, and the same parts in the drawings are given the same reference numerals and their explanation is omitted. By providing the lands 51, 53 and through hole 55, the seating of the nut 21 or flanged nut 21' can be stabilized, and loosening caused by vibration and thermal cycles can be suppressed. When the occurrence of loosening cannot be prevented by the nut 21 alone, a spring washer and a flat washer may be added between the nut 21. In that case, if the length of the cell stud 9 is insufficient, the length is changed.

[0033] Next, a sixth embodiment of the present invention will be described with reference to Figures 13 and 14. Figure 13(a) is a plan view of a state in which a plurality of (four in this case) power semiconductors 11 are installed, as seen through a substrate 17, and Figure 13(b) is a cross-sectional view taken along line bb of Figure 13(a). A boss 61 for fixing the substrate 17 is protrudingly provided on the housing 1, and the substrate 17 is fixed to the housing 1 by screwing a fixing screw 63 through the substrate 17 into a female threaded portion 65 provided on the boss 61. Incidentally, the fixing screws 63 are not shown in FIG.

[0034] In the structure shown in FIG. 13, the mounting hole 19 of the board 17 provided on the female screw portion 65 is a non-through hole, and the seating surface of the fixing screw 63 is the insulating layer (glass cloth fiber) of the board 17. There is a concern that the board 17 may be warped and distorted by the compression of the heat dissipation sheet 7 before the fixing screw 63 is seated on the board 17. This is also due to the presence of a space between the boss 61 and the power semiconductor 11 .

[0035] To prevent this, in the present embodiment, a heat-resistant resin molded product 71 is inserted between the substrate 17 and the heat sink 5 as shown in FIG. The other configurations are the same as those of the first embodiment, and the same parts in the drawings are given the same reference numerals and their explanation is omitted. By inserting the molded product 71, the occurrence of distortion due to warping of the substrate 17 can be suppressed.

[0036] Next, a seventh embodiment of the present invention will be described with reference to Fig. 15. In the seventh embodiment, a metal terminal 81 is provided so as to straddle two nuts 21, 21 and a fixing screw 63. The other configurations are the same as those of the first embodiment, and the same parts in the drawings are given the same reference numerals and their explanation is omitted. By providing the metal terminals 81, the occurrence of distortion due to warping of the substrate 17 can be suppressed.

[0037] Next, an eighth embodiment of the present invention will be described with reference to Fig. 16. In the eighth embodiment, dummy patterns 91 for predetermined display are provided across multiple layers (four layers in this embodiment) on the substrate 17. Through holes 93 are provided between the dummy patterns 91. The other configurations are the same as those of the first embodiment, and the same parts in the drawings are given the same reference numerals and their explanation is omitted. By providing the dummy pattern 91, the occurrence of distortion due to warping of the substrate 17 can be suppressed.

[0038] Next, a ninth embodiment of the present invention will be described with reference to Fig. 17. In the case of this ninth embodiment, a slit-shaped through hole 95 is provided in the configuration of the eighth embodiment. The other configurations are the same as those of the eighth embodiment, so the same parts in the drawings are given the same reference numerals and their explanations are omitted. By providing the slit-like through-holes 95, the occurrence of distortion due to warping of the substrate 17 can be suppressed.

[0039] Next, a tenth embodiment of the present invention will be described with reference to Fig. 18. In this case, a fully molded package "TO-220F" is selected as the power semiconductor. In this case, a space is generated between the mounting hole 13 of the power semiconductor 11 and the mounting hole 19 of the substrate 17. Therefore, when the cell stud 9 is inserted and the nut 21 is screwed, the substrate 17 may be distorted and buckled at the seating surface, which may cause problems with fixing. Therefore, it is conceivable to insert a collar (spacer) 95 made of metal or heat-resistant resin into the above-mentioned space. In addition, when the non-molded package "TO-220AB" is selected, a collar (spacer) 95 that can provide insulation is inserted into the mounting hole 13 of the power semiconductor 11. However, if the heat sink 5 and the cell stud 9 have the same potential and insulation is not required, metal may be used.

[0040] Incidentally, the present invention is not limited to the first to ninth embodiments. First, the case has been described as an example, but the present invention can also be applied to a heat sink. Additionally, the configurations shown in the drawings are merely examples. [Industrial Applicability]

[0041] The present invention relates to a mounting structure for power semiconductors, and in particular to one that is devised to suppress temperature rise and achieve high output, and is suitable for example for a mounting structure for power semiconductors in a vehicle control device. [Explanation of symbols]

[0042] 1 Case 5 Heat sink 7 Soft heat dissipation sheet 9 Cell Stud 11 Power Semiconductors 13 Mounting hole 15 Rubber heat dissipation sheet 16 Mounting holes 17 Substrate 19 Mounting hole 21 Nut 21´ Flange Nut 23 Lead terminal 25 through hole 27 Heat Center 31 Ground terminal for circuit board mounting (nut seating stabilizing member) 43 Flat washer (nut seating stabilization part) 51 Land (nut seating stabilizing member) 53 Land (nut seating stabilization member) 71 Molded products (substrate support members) 81 Metal terminal (substrate support member) 91 Dummy pattern (substrate support member)

Claims

1. Generate a part with a heat sink and a cell stud attached, Provide mounting holes on the power semiconductor and board, The power semiconductor is placed on the heat sink by inserting the cell stud into the mounting hole of the power semiconductor; The cell stud is inserted into the mounting hole of the substrate, and the substrate is placed on the power semiconductor. A mounting structure for a power semiconductor, characterized in that a nut is screwed onto the cell stud protruding from the mounting hole of the substrate to fix the cell stud in place.

2. The mounting structure for a power semiconductor according to claim 1, Mounting holes are provided in the rubber heat dissipation sheet, the cell stud is inserted through the mounting hole of the rubber heat dissipation sheet, and the rubber heat dissipation sheet is placed on the heat dissipation plate; A power semiconductor mounting structure, on which the power semiconductor is mounted.

3. The mounting structure for a power semiconductor according to claim 1, A mounting structure for power semiconductors, characterized in that the part is a sheet metal part formed by pressing the metal cell stud into a mounting hole provided in the heat sink made of aluminum or copper.

4. The mounting structure for a power semiconductor according to claim 1, A mounting structure for a power semiconductor, characterized in that the heat sink is installed on a mounting base of a housing or a heat sink.

5. The power semiconductor mounting structure according to claim 4, A power semiconductor mounting structure, characterized in that a soft heat dissipation sheet is interposed between the heat sink and the mounting base.

6. The mounting structure for a power semiconductor according to claim 1, The power semiconductor is an insertion-mount type power semiconductor, and a lead terminal is taken out from the power semiconductor, and the lead terminal is bent and inserted into a through hole of the substrate.

7. The mounting structure for a power semiconductor according to claim 1, A power semiconductor mounting structure, characterized in that a nut seating stabilization member is interposed between the nut and the board to prevent the nut from loosening.

8. The mounting structure for a power semiconductor according to claim 1, The mounting structure for a power semiconductor, wherein the nut is a flanged nut.

9. The power semiconductor mounting structure according to claim 4, The housing or the heat sink has bosses for fixing the substrate protruding therefrom, The substrate is fixed to the substrate fixing boss by a fixing screw, a substrate support member is interposed between the substrate and the heat sink on an outer periphery of the substrate fixing boss, the substrate support member being disposed on the outer periphery of the substrate fixing boss and the heat sink;

10. The power semiconductor mounting structure according to claim 4, A mounting structure for a power semiconductor, characterized in that a board support member is interposed on the board below the nut and the fixing screw so as to straddle the nut and the fixing screw.

11. The power semiconductor mounting structure according to claim 4, The housing or the heat sink has bosses for fixing the substrate protruding therefrom, The substrate is fixed to the substrate fixing boss by a fixing screw, A mounting structure for a power semiconductor, characterized in that a plurality of dummy patterns are stacked and connected via through holes in the substrate so as to straddle the mounting holes of the cell studs and the mounting holes of the fixing screws.

12. The power semiconductor mounting structure according to claim 11, A mounting structure for a power semiconductor, characterized in that a slit-shaped through hole is provided in the substrate near the dummy pattern.

13. The power semiconductor mounting structure according to claim 1, A power semiconductor mounting structure, characterized in that when a space is formed between the mounting hole of the power semiconductor and the mounting hole of the board, a board support member is inserted into the space.

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