Power module

Abstract

In a power module (100), a substrate on which semiconductor components including a bridge-forming component (5) are mounted is sealed with a mold resin. The bridge-forming component (5) includes a first bridge (bridge (31)) that bridges a first semiconductor component (1) and a second semiconductor component (2). On the surface of the mold resin after sealing at least a portion in the vicinity (34) of a projection surface of the first bridge, a recess is provided between a gate-side boundary (35) and an opposite-to-gate-side boundary (36) of the first bridge between the first semiconductor component (1) and the second semiconductor component (2).

Description

Power Module

[0001] The present invention relates to a power module for transfer molding.

[0002] The mold encapsulation process for power modules is a manufacturing method in which components to be encapsulated, such as substrates, are placed in a mold cavity, and then molded with molding resin to integrally encapsulate the components. Power modules manufactured using this process are widely used as power modules for various applications.

[0003] This mold encapsulation process requires replacing the air in the mold cavity with the molding resin. However, because the leading edge of the resin flow comes into contact with the air in the mold cavity, the flow is prone to turbulence, making it easy for voids to form due to air entrapment. Furthermore, when the components to be encapsulated are stacked with multiple substrates or components, with gaps between them, voids are likely to form due to air entrapment between the substrates or between the substrates and components. These voids can cause problems such as poor insulation and poor appearance.

[0004] Manufacturing methods to prevent these voids include specifying the spacing between substrates and installing a restriction in the mold to control the flow of molding resin, thereby increasing the amount of resin between the components to be sealed.

[0005] For example, Patent Document 1 discloses a specification of the spacing between substrates for molding a power module.

[0006] 9, paragraph 0056, 11, and paragraph 0060 of Patent Document 1 state that "the relationship between the distance A between the upper surface of the mold resin and the topmost substrate, the distance B between the substrates, and the distance C between the lower surface of the mold resin and the bottommost substrate is A=B=C, which has the effect of preventing voids from being generated between the substrates," and "the relationship between the distance A between the upper surface of the mold resin and the topmost substrate, the distance B between the substrates, and the distance C between the lower surface of the mold resin and the bottommost substrate is A, C≦B, which has the effect of preventing voids from being generated between the substrates." In other words, Patent Document 1 states that specifying the distance relationship between each substrate has the effect of suppressing voids from being generated between the substrates.

[0007] Furthermore, for example, Patent Document 2 discloses the provision of a throttle portion for controlling the flow of molding resin into a mold.

[0008] FIG. 1 and the abstract of Patent Document 2 state that the problem is to "improve the injectability of resin into the insulating layer portion immediately below the heat spreader in transfer molding of a resin-packaged semiconductor device," and as a solution to this problem, they state that "a frame processed portion is formed in advance on the lead frame by bending upward the tip end of the inner lead portion of the lead frame located between both chips and both wiring wires. Resin is then injected into the cavity of the molding die to perform molding. In this case, the frame processed portion functions as a restrictor that restricts the amount of resin injected that attempts to flow to the top of the lead frame, and the amount of resin that flows from the bottom of the lead frame into the portion where the insulating layer is formed immediately below the heat spreader increases."

[0009] More specifically, in Figure 3 and paragraphs 0021 and 0022 of Patent Document 2, it is stated that "Figure 3 is a vertical cross-sectional view showing the internal structure of a resin-packaged semiconductor device according to this embodiment after transfer molding is completed," and "A feature of this embodiment is that a protrusion (not shown) corresponding to the shape of the groove is provided in advance on the upper die of a pair of molding dies so that a groove is formed after transfer molding is completed between the chips lined up in the resin injection direction, i.e., in the portion of the resin package located between both wiring wires, and this protrusion is used to perform transfer molding." In other words, Patent Document 2 describes providing a groove-shaped drawn portion in the die so as to prevent an unfilled portion from being formed in the insulating layer portion, which is much thinner than the thickness of the upper part of the chip.

[0010] JP 2010-56355 A JP 2003-115505 A

[0011] Patent Document 1 specifies the distance between substrates and the distance between the top surface of the molding resin and the topmost substrate. However, when semiconductor components are mounted on a substrate, particularly components that form bridges, voids may occur due to air entrapment below the bridges.

[0012] In addition, in Patent Document 2, for example, a mold with a protrusion on the corresponding portion of the upper mold may be used to form a groove on the upper surface of the mold resin. In this case, unlike the entire upper portion of the substrate or the entire insulating layer to be filled, voids due to air entrapment may occur below the bridge in components that form bridges on the substrate. In this case, if voids remain, moisture may accumulate in the void, resulting in performance problems such as reduced insulation. Furthermore, because the resin thickness in the groove is thin, there is a concern that the strength of the module may be reduced.

[0013] Here, Patent Documents 1 and 2 are intended for use with large-area substrates such as substrates on which semiconductor chips are mounted or heat spreaders, and therefore do not take into consideration filling the lower parts of bridges of components that form multiple bridges mounted on a substrate during a mold sealing process. Therefore, they do not take into consideration the structure of a mold suitable for filling the lower parts of the bridges with resin or the structure of the components that form the bridges.

[0014] The problem to be solved by the present invention is to provide a power module that can suppress the generation of voids below the bridge of a component that forms a bridge when semiconductor components including the component that forms a bridge on a substrate are sealed with a mold resin.

[0015] In order to solve the above-mentioned problems, the power module of the present invention is a power module in which a substrate on which semiconductor components including bridge-forming components that form a bridge are mounted is sealed with a mold resin, and is characterized in that a first bridge among the bridge-forming components that bridges a first semiconductor component and a second semiconductor component has a recess on at least a part of the surface of the mold resin after sealing in the vicinity of a projection plane of the first bridge, the first bridge having a gate-side boundary and a gate-opposite boundary, and between the first semiconductor component and the second semiconductor component. Other aspects of the present invention will be described in the embodiments described later.

[0016] According to the present invention, when a substrate on which semiconductor components including bridge-forming components are mounted is sealed with molding resin, it is possible to prevent voids from remaining under the bridge formed by the bridge-forming components, thereby preventing a decrease in insulation performance.

[0017] 8A , 8B , 8C , 8D , 8E , 8F , 8G , 8H , 8H , 8G ...

[0018] Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. In each drawing and each embodiment, the same or similar components are designated by the same reference numerals, and redundant explanations will be omitted.

[0019] <First Embodiment> Fig. 1 is a top view 1A and a D-D cross-sectional view 1B illustrating the schematic configuration of a power module before encapsulation manufactured by a power module manufacturing method according to a first embodiment. As shown in top view 1A in Fig. 1, first, a first semiconductor component 1 and a second semiconductor component 2 are mounted on a substrate 3. Furthermore, bonding portions 18 of bridge-forming component 5 are bonded to first semiconductor component 1 and second semiconductor component 2, and bonding portions 19 and 19B are bonded to bonding member 21. Although the mold resin is not shown in top view 1A because the top view is before encapsulation, the mold resin is poured in the direction indicated by the arrow in resin flow direction 8, and the power module is encapsulated by the mold resin.

[0020] As shown in the D-D cross-sectional view 1B of FIG. 1 , the bridge 31 serves as a bridge from the first semiconductor component 1 to the second semiconductor component 2 via the bridge-forming component 5. The first semiconductor component 1 and the second semiconductor component 2 require electrical conduction, so they are connected by the bridge 31. In particular, because a high voltage is applied to the bridge 31, the space below the bridge 31 must be highly insulating and must be free of voids. The bridge 32 serves as a bridge from the bonding member 21 to the first semiconductor component 1 via the bridge-forming component 5. The bridge 33 serves as a bridge from the second semiconductor component 2 to the bonding member 21 via the bridge-forming component 5. When the power module is operating, the first semiconductor component 1 and the second semiconductor component 2 generate heat, which is then dissipated to the substrate 3 via the bridge 32 and bridge 33 (and further via the bonding members 21, 21).

[0021] As shown in the top view 1A of FIG. 1, the connected structure is sealed with mold resin in the resin flow direction 8. The vicinity 34 of the projection surface of the bridge 31 in the top view 1A will be described. In the bridge-forming component 5, the end of the bridge 31 to which the mold resin flows first in relation to the resin flow direction 8 is designated as the gate-side boundary 35 (see gate 14 in FIG. 4). In the bridge-forming component 5, the end of the bridge 31 to which the mold resin flows last is designated as the gate-side boundary 36. The vicinity 37 of the projection surface of the entire bridge-forming component 5 is also shown in the top view 1A. In the D-D cross-sectional view 1B of FIG. 1, the upper surface portions of the bridge-forming component 5 corresponding to the joints 18, 19, and 19B of the bridge-forming component 5 are recessed, but they may also have a flat structure.

[0022] The projection surface is the portion of the molded resin where the bridge 31 is located when the power module sealed with the molded resin is viewed from above as in Top View 1A, in other words, the portion of the molded resin that covers the bridge 31. The vicinity of the projection surface is the projection surface and its peripheral portion (the peripheral portion including the projection surface), and is the portion surrounded by a dashed line in Top View 1A (proximity of the projection surface 34).

[0023] 2 is a top view illustrating the schematic configuration of a power module manufactured by the power module manufacturing method of the first embodiment. The power module 15 according to this embodiment is manufactured by sealing a substrate 3 on which a first semiconductor component 1 and a second semiconductor component 2, including a bridge-forming component 5, are mounted with a molding resin 4. The power module 15 is also called a semiconductor device.

[0024] The substrate 3 may be, for example, a DBC (Direct Bonded Copper) substrate in which a wiring pattern is formed on an insulating substrate. Note that the wiring pattern is not shown in Fig. 2. Any insulating substrate such as a glass epoxy substrate or a paper phenol substrate may be used as the insulating substrate of the substrate 3. The wiring pattern of the substrate 3 may be made of, for example, copper.

[0025] The first semiconductor component 1 is, for example, a semiconductor chip. The first semiconductor component 1 is joined to a wiring pattern formed on the substrate 3 via a joining member such as solder. The bridge-forming component 5 is, for example, a small lead frame piece. The bridge-forming component 5 is joined to the first semiconductor component 1 and the wiring pattern formed on the substrate 3 via a joining member (joint member 21) such as solder.

[0026] Although not shown, electrical signals can be transmitted to the outside by a wiring pattern formed on the back side of the substrate 3, which side does not have the first semiconductor component 1 mounted thereon. Note that the configuration is not limited to this, and for example, a wiring member such as a lead frame may be electrically connected to the wiring pattern of the substrate 3 or the first semiconductor component 1 by a connecting member such as gold wire or aluminum wire, thereby transmitting electrical signals to the outside.

[0027] The mold resin 4 that seals the substrate 3 on which the first semiconductor component 1 and the second semiconductor component 2, including the bridge-forming component 5, are mounted can be, for example, a thermosetting resin whose main component is epoxy resin, phenol resin, or polyester resin. The thermosetting resin of the mold resin 4 can be filled with a filler. Examples of fillers that can be used include inorganic materials containing components such as silica, mica, and talc; organic materials containing components such as carbon and polymeric materials; and metal materials containing components such as copper, aluminum, gold, silver, and iron.

[0028] Although not shown, wiring patterns or wiring members for transmitting electrical signals to the outside are exposed from the molding resin 4 .

[0029] Furthermore, a recess 6 is formed on the surface of the molded resin 4 of the power module 15. This recess 6 is formed on the surface of the molded resin 4 using a mold 22 (see FIG. 4 ) having a mold protrusion 7 (described later) in a mold sealing process. The recess 6 is formed in the vicinity 34 of the projection plane of the bridge 31, between a portion including a gate-side boundary 35 of the bridge 31 and an opposite-side boundary 36 of the gate, and between the first semiconductor component 1 and the second semiconductor component 2, i.e., near a position of the bridge-forming component 5 corresponding to the bridge 31. The recess 6 may be formed with a draft angle to facilitate removal of the molded resin 4 after molding. Although not shown, a cooling member may be provided on the back side of the substrate 3.

[0030] Fig. 3 is a top view illustrating a method for manufacturing a power module according to the first embodiment and a schematic configuration of a mold 22 used therein. Fig. 4 is a cross-sectional view taken along the line A-A in Fig. 3. The method for manufacturing a power module according to this embodiment includes a substrate placement step in which a substrate 3 on which semiconductor components including a bridge-forming component 5 are mounted is placed in a cavity 11 (gap) in the mold 22, and a resin sealing step in which mold resin 4 is filled into the cavity 11 to resin-seal the substrate 3 on which a first semiconductor component 1 is mounted. Figs. 3 and 4 show the state after the substrate placement step has ended and before the next resin sealing step is performed.

[0031] Here, the mold 22 includes a cavity 11 in which the substrate 3 on which semiconductor components including the bridge-forming component 5 are mounted is placed, a flow cavity (not shown in FIG. 3) that accommodates the molding resin 4 that overflows from the cavity 11, a flow path (not shown in FIG. 3) for guiding a portion of the molding resin 4 to the flow cavity, and mold protrusions 7 that are arranged between the first semiconductor component 1 and the second semiconductor component 2, i.e., in correspondence with each bridge 31 (see FIG. 1) of the bridge-forming component 5, in order to form recesses 6 on the surface of the molding resin 4 after sealing. Details of the recesses 6 and the bridge-forming component 5 will be described later.

[0032] The mold 22 has a structure in which the upper mold 12 and the lower mold 13 are sandwiched from above and below in the Z direction by clamps of a molding device (not shown). As shown in Figure 4, a substrate 3 on which semiconductor components including a bridge-forming component 5 are mounted is placed in a cavity 11, which is a space formed at the boundary between the upper mold 12 and the lower mold 13. The temperature of the mold 22 is adjusted by a heater or the like, and the molding resin 4 inserted into the pot portion 10 is heated and melted. After that, a load is applied from the positive direction in the Z direction by the molding device, and the molding resin 4 is filled into the cavity 11 through a runner 9, which is a flow path for the molding resin 4 in the mold 22, and a gate 14, which is an entrance to the cavity 11, and the substrate 3 on which semiconductor components including a bridge-forming component are mounted is sealed with the molding resin 4.

[0033] The molded resin 4 overflowing from the cavity 11 is received in the flow cavity via the flow path, and after the molded resin 4 is cooled and hardened, the molded resin 4 that has filled the runner 9, the flow path, and the flow cavity is separated from the power module 15 and discarded. Note that the runner 9 portion is thinner than the gate 14, making it easier to separate the molded resin 4 from the runner 9. In addition, since the molded resin 4 does not flow into the area where the mold protrusion 7 is located, a depression 6 can be formed.

[0034] The cavity 11 of the mold 22 can be depressurized before filling with the molding resin 4, and an air vent, which is a minute space communicating with the outside of the mold 22 and through which air can flow but not the molding resin 4, is partially provided at the boundary between the upper mold 12 and the lower mold 13. Although not shown, the mold 22 may have a structure including a fixing mechanism or a fixing groove for the substrate 3 in order to fix the substrate 3 in the cavity 11.

[0035] 5 is a cross-sectional view illustrating the schematic configuration and problems of an electronic control device of a mold 22 of a comparative example. State 5B shows a state after State 5A. A is the distance between the upper surface of the molding resin and the top substrate, B is the distance between the substrates, and C is the distance between the lower surface of the molding resin and the bottom substrate. The two upper and lower substrates 3 are supported by in-plane support parts 16, and a lead frame 17 is provided on the lower substrate.

[0036] The comparative example has a structure in which multiple substrates 3 are stacked and molded. In the mold sealing process, it is necessary to replace the air in the cavity 11 of the mold 22 with the mold resin 4. However, since the leading edge of the flow of the mold resin 4 comes into contact with the air in the cavity 11, the flow is prone to become turbulent, and voids 20 are likely to occur due to the entrainment of air. These voids 20 at the leading edge of the flow gather near the final filling portion, and the mold resin 4 hardens and solidifies. As a result, the voids 20 are exposed on the surface of the mold resin 4 of the power module 15 near the final filling portion, causing a problem of poor appearance.

[0037] To prevent this void 20 from remaining in the molded resin 4 of the power module 15 and causing problems with poor appearance, a flow cavity (not shown) is installed near the final filling section to pour the void 20 together with the molded resin 4 through a flow path (not shown).

[0038] However, when multiple substrates 3 are stacked, voids 20 may be formed between the substrates, and the voids 20 may remain, causing problems such as peeling off of the substrates 3 or poor insulation.

[0039] 5, it is conceivable to install the substrates so that the relationship between the distance A between the upper surface of the mold resin and the uppermost substrate, the distance B between the substrates, and the distance C between the lower surface of the mold resin and the lowermost substrate satisfies A, C ≤ B. This relationship has the effect of preventing voids from being introduced into the space above the various components mounted on the substrates.

[0040] However, when bridge-forming components 5 are present on substrate 3, the narrow gap below the bridge slows the flow rate of the molded resin below the bridge. As a result, the flow rate of the molded resin above the bridge becomes relatively faster, and the molded resin 4 flowing above the bridge flows down from the top of the bridge onto substrate 3 first, trapping air below the bridge and leaving voids 20 below the bridge. As shown in state 5B, voids 20 remain below each bridge, causing the problem of poor insulation.

[0041] Fig. 6 is a top view of part B in Fig. 3. Fig. 7 is a cross-sectional view of part B along line A-A in Fig. 3. A schematic configuration of the vicinity of the mold protrusion 7 of the mold of the first embodiment will be described with reference to Fig. 6 and Fig. 7. State 7B in Fig. 7 shows a state subsequent to state 7A.

[0042] In order to solve the problems of the comparative example, the mold 22 of this example is configured to have a mold protrusion 7 corresponding to the bridge portion near the projection plane 34 of the bridge 31 of the bridge-forming component 5, so that the distance H1 between the underside of the bridge portion of the bridge-forming component 5 and the substrate and the thickness H2 of the molded resin at the upper part of the bridge portion satisfy the relationship H1 > H2, as shown in Figures 6 and 7. This makes the flow rate of the molded resin 4 flowing below the bridge portion relatively faster than that of the upper part of the bridge portion, allowing the molded resin 4 to fill the lower part of the bridge portion first. This makes it possible to prevent voids 20 from remaining below the bridge, which is directly below the bridge portion to which a high voltage is applied, and thus prevent poor insulation.

[0043] A thicker bridge portion thickness H3 is preferable for dissipating heat from semiconductor components, but power modules are required to be smaller and thinner, and while increasing the distance H1 would be sufficient to suppress voids, the larger H1 increases the total thickness of the module. Therefore, to reduce the total thickness of the module, it is desirable that the distance H1 between the underside of the bridge portion of the bridge-forming component 5 and the substrate and the bridge portion thickness H3 satisfy the relationship H3 > H1.

[0044] 8A is a cross-sectional view taken along CC in FIG. 6 , illustrating a schematic configuration of the vicinity of die protrusion 7 of the die according to the first embodiment. Bridge 31 is a bridging structure extending from first semiconductor component 1 to second semiconductor component 2 via bridge-forming component 5. Bridge 32 is a bridging structure extending from bonding member 21 to first semiconductor component 1 via bridge-forming component 5. Bridge 33 is a bridging structure extending from second semiconductor component 2 to bonding member 21 via bridge-forming component 5.

[0045] Figure 8B is a cross-sectional view showing a modified example of Figure 8A, with the mold convex area enlarged. The area where the mold convex area 7 is formed relative to the bridge-forming component 5 is preferably the same depth (horizontal in the figure) as the entire length of the bridge-forming component 5, as shown by the mold convex area (maximum depth) 7L in Figure 8B. This is because if the depth of the mold convex area 7 is within the range of the bridge 31, air will be trapped in the bridges 32 and 33 at the ends of the bridge-forming component 5, increasing the likelihood of voids 20 remaining. While the voids 20 do not directly lead to insulation failure, moisture accumulated in the voids may cause corrosion of the joint. To remove the voids 20 from below the bridges 32 and 33, additional molding resin 4 can be introduced through the gate 14 even after the cavity 11 is completely filled. However, the flow below the bridges is slow, resulting in a large amount of resin waste.

[0046] Furthermore, a power module may be manufactured by forming the shape of the mold protrusion 7 of the upper mold 12 on a mold release film (not shown) used in the mold for transfer molding.

[0047] Second Embodiment The second embodiment is a modification of the first embodiment, and will be described with reference to Fig. 9. Fig. 9 is a cross-sectional view illustrating a schematic configuration of a bridge portion of a bridge-forming component 5 of a power module according to the second embodiment. Fig. 9 shows an example of the shape of a recess 6.

[0048] Shape 9A has a significantly narrower recess width. The recess width is set between the portion including the gate-side boundary 35 and the gate-opposite boundary 36 in the vicinity 34 of the projection plane of the bridge 31. This makes it suitable for resins with little difference in fluidity between the upper and lower portions of the bridge.

[0049] The shape 9B has a widened V-shape, which is suitable for resins with high viscosity and low fluidity.

[0050] Shape 9C has an asymmetric recess. This allows the height of the recess to gradually decrease after it protrudes, further suppressing the generation of voids. Similarly, the structure in which the thickness of the molding resin gradually increases maintains the strength of the molded package.

[0051] The shape 9D has curved corners of the shape 9A, which can reduce stress on the corners that occurs after the molding resin 4 hardens.

[0052] Third Embodiment The third embodiment is a modification of the first embodiment and will be described with reference to Fig. 10. Fig. 10 is a top view illustrating a schematic configuration of a joint between a bridge-forming component 5 and a substrate of a power module according to the third embodiment. Fig. 10 shows an example of the joint shape between the bridge-forming component 5 and the substrate.

[0053] In shape 10A, the upper surface of the bridge-forming component 5 is flat all the way to the edge. The cross-sectional shape of the bridge 38 is the same as the cross-sectional shape of the bridge 33. This ensures a wide gap below the bridge 38, making it possible to suppress voids remaining below the bridge 38.

[0054] In shape 10B, the upper surface of the bridge-forming component 5 is flat all the way to the upper end. At the lower end of the bridge-forming component 5, the joint with the substrate is inclined, and the joint is closer to the substrate. The cross-sectional shape of bridge 38 is the same as the cross-sectional shape of bridge 33. This ensures a wide gap below bridge 38, making it possible to suppress voids remaining below bridge 38. The cross-sectional shape of bridge 39 is the same as the cross-sectional shape of bridge 32. Bridge 39 is closer to the substrate, making heat dissipation from the semiconductor component more efficient.

[0055] In shape 10C, the upper surface of the bridge-forming component 5 is inclined at both the upper and lower ends, and is joined at a position closer to the substrate. The cross-sectional shape of bridge 39 is the same as the cross-sectional shape of bridge 32. This brings both the upper and lower ends closer to the substrate, making heat dissipation from the first semiconductor component 1 even more efficient.

[0056] The shapes 10D, 10E, and 10F are examples of the shapes 10A, 10B, and 10C configured as one chip.

[0057] <Fourth Embodiment> The fourth embodiment is a modification of the first embodiment, and will be described with reference to Fig. 11. Fig. 11 is a top view illustrating a schematic configuration of the shape in which the bridge-forming components 5 of the power module according to the fourth embodiment are routed to the substrate 3. Fig. 11 shows an example of the shape in which the bridge-forming components 5 are routed to the substrate 3.

[0058] In the shape 11A, the bridge-forming component 5 is I-shaped, which makes it possible to reduce the mounting area.

[0059] In shape 11B, the bridge-forming components 5 are C-shaped. The width of the bridge-forming components 5 of bridges 40 and 41 is wider than in shape 11A. This allows for more efficient heat dissipation from the first semiconductor component 1 and the second semiconductor component 2. The cross-sectional shape of bridge 40 is the same as the cross-sectional shape of bridge 32. The cross-sectional shape of bridge 41 is the same as the cross-sectional shape of bridge 33.

[0060] In the shape 11C, the bridge-forming component 5 is L-shaped. The cross section of the bridge 42 has the same shape as the cross section of the bridge 32. This allows heat to be dissipated from the first semiconductor component 1 with priority.

[0061] In shape 11D, the bridge-forming component 5 is S-shaped. This allows for efficient heat dissipation from the first semiconductor component 1 and the second semiconductor component 2. The cross-sectional shape of the bridge 43 is the same as the cross-sectional shape of the bridge 33. This ensures a wide gap below the bridge 43, potentially reducing voids. The corners of the above shape may also be curved.

[0062] Fifth Embodiment The fifth embodiment is a modification of the first embodiment, and will be described with reference to Fig. 12. Fig. 12 is a cross-sectional view illustrating a schematic configuration of a bridge portion of a bridge-forming component 5 of a power module according to the fifth embodiment. Fig. 12 shows an example of the shape of an end portion of a cross-sectional portion of the bridge portion of the bridge-forming component 5.

[0063] In the shape 12A, the end of the cross section of the bridge portion is formed into a vertical surface shape, which allows the bridge-forming component 5 to be produced at low cost.

[0064] In the shape 12B, the end of the cross section of the bridge portion is formed into a tapered surface shape, which allows the amount of molding resin 4 to be filled in the lower part of the bridge portion to be increased.

[0065] Shape 12C has a protruding surface at the end of the cross section of the bridge portion. This, combined with the shape of the recess 6, allows for smooth resin flow to the upper and lower parts of the bridge portion, further suppressing the occurrence of voids. The corners of the above shape may also be curved.

[0066] The method for manufacturing a power module of this embodiment is, for example, a method for manufacturing a power module in which a substrate on which semiconductor components including bridge-forming components are mounted is sealed with mold resin, and includes a substrate placement step of placing the substrate on which semiconductor components are mounted in a cavity in a mold, and a resin sealing step of filling the cavity with mold resin to resin-seal the substrate on which the semiconductor components are mounted, and the mold includes mold convex portions 7 arranged corresponding to the bridge portion projection plane in order to form depressions 6 on the surface of the mold resin after sealing. The new structure of partial depressions on the mold resin surface makes the gap between the lower surface of the bridge portion of the bridge-forming component and the substrate larger than the gap between the upper surface of the bridge portion and the inner surface of the mold, thereby increasing the resin flow rate below the bridge, and the resin below the bridge flows before the upper bridge, thereby suppressing voids below the bridge.

[0067] Furthermore, the mold of the embodiment is, for example, a mold used in manufacturing a power module in which a substrate mounted with semiconductor components including a bridge-forming component is sealed with mold resin, and includes a cavity in which the substrate mounted with the semiconductor components is placed, and mold protrusions 7 arranged on the projection surface of the bridge portion of the component to form depressions in the surface of the mold resin after sealing. The mold is characterized by a new structure of partial depressions 6 on the mold resin surface, which makes the gap between the lower surface of the bridge portion of the bridge-forming component and the substrate larger than the gap between the upper surface of the bridge portion and the inner surface of the mold, thereby increasing the resin flow rate below the bridge, and causing the resin below the bridge to flow before the resin above the bridge, thereby suppressing voids below the bridge.

[0068] According to the power module manufacturing method and mold of this embodiment, when a substrate on which semiconductor components including bridge-forming components are mounted is sealed with a mold resin, it is possible to prevent voids from remaining below the bridge of the bridge-forming components, thereby preventing a decrease in insulation performance.

[0069] As described above, the power module of this embodiment has the following features: (1) A power module 100 in which a substrate 3 on which semiconductor components including a bridge-forming component 5 are mounted is sealed with a mold resin, and a first bridge (bridge 31) of the bridge-forming component 5 that bridges the first semiconductor component 1 and the second semiconductor component 2 has a recess 6 on at least a portion of the surface of the mold resin after sealing in the vicinity 34 of the projection plane of the first bridge (bridge 31), between a gate-side boundary 35 of the first bridge and an opposite-side boundary 36 of the gate, and between the first semiconductor component 1 and the second semiconductor component 2 (see FIGS. 1 and 2 ). This makes it possible to prevent voids from remaining below the bridge of the bridge-forming component, which would otherwise reduce insulation performance, when the substrate on which semiconductor components including the bridge-forming component are mounted is sealed with the mold resin.

[0070] The projection surface is the resin molded portion that covers the bridge when the resin-molded power module (semiconductor device) is viewed from above, with the bridge located below it.

[0071] (2) In the power module 100 of (1) above, in the first bridge of the bridge-forming component 5, the distance H1 between the underside of the bridge portion of the bridge-forming component 5 and the substrate 3 and the thickness H2 of the molded resin at the top of the bridge portion have a relationship of H1 > H2, and the bridge portion thickness H3 has a relationship of H1 < H3 (see FIG. 7 ). According to this, by making the distance between the underside of the bridge portion of the bridge-forming component 5 and the substrate larger than the distance between the top of the bridge portion and the inner surface of the mold, the resin flow rate at the bottom of the bridge becomes faster, and the resin at the bottom of the bridge flows before the resin at the top of the bridge, which has the effect of suppressing voids at the bottom of the bridge.

[0072] (3) The power module 100 of (1) has a recess 6 in the vicinity 34 of the projection plane of the first bridge of the bridge-forming component 5, between a portion including the gate-side boundary 35 of the first bridge and not exceeding the opposite-side boundary 36 of the gate, and between the first semiconductor component 1 and the second semiconductor component 2 (see FIG. 7). This has the effect of suppressing voids on the underside of the bridge portion.

[0073] (4) In the power module 100 of (1) above, in the vicinity 37 of the projection surface of the entire bridge-forming component 5, a recess corresponding to the entire vicinity 37 of the projection surface is formed on the surface of the molded resin after sealing (see FIG. 8B ). This has the effect of suppressing voids in a wide area under the bridge portion.

[0074] (5) In the power module 100 of (1), a recess having an asymmetric cross-sectional shape is formed on the surface of the molded resin after sealing in the vicinity 34 of the projection plane of the first bridge of the bridge-forming component 5 (see shape 9C in Figure 9).

[0075] (6) The power module 100 of (1) has a curved recess without corners on the surface of the molded resin after sealing in the vicinity 34 of the projection surface of the first bridge of the bridge-forming component 5 (see shape 9D in Figure 9).

[0076] (7) In the power module 100 of (1) above, in the first bridge of the bridge-forming component 5, the second bridge (bridge 32) bridging the first semiconductor component 1 and the substrate 3, and the third bridge (bridge 33) bridging the second semiconductor component 2 and the substrate 3, the end of the gate-side boundary 35 of each bridge cross section has a tapered or protruding surface shape (see shapes 12B and 12C in FIG. 12). This has the effect of suppressing voids on the underside of the bridge portion.

[0077] Although the embodiments of the present invention have been described above, the present invention is not limited to the configurations described in the embodiments, and various modifications are possible within the scope of the technical concept of the present invention. In addition, some or all of the configurations described in each embodiment may be combined and applied.

[0078] 1 First semiconductor component 2 Second semiconductor component 3 Substrate 4 Molded resin 5 Bridge-forming component 6 Depression 7 Mold protrusion 7L Mold protrusion (maximum depth) 8 Resin flow direction 9 Runner 10 Pot portion 11 Cavity (hollow) 12 Upper mold 13 Lower mold 14 Gate 15 Power module 16 In-plane support component 17 Lead frame 18 Joint portion (joint portion between bridge-forming component and semiconductor component) 19 Joint portion (joint portion between bridge-forming component and substrate) 19B Joint portion (joint portion between bridge-forming component and substrate) 20 Void 21 Joint member 22 Mold 31 Bridge (first bridge) 32 Bridge (second bridge) 33 Bridge (third bridge) 34 Near the projection surface 35 Gate-side boundary 36 Opposite boundary of gate 37 Near the projection surface 38 Bridge 39 Bridge 40 Bridge 41 Bridge 42 Bridge 43 Bridge

Claims

1. A power module in which a substrate on which semiconductor components including bridge-forming components that form a bridge are mounted is sealed with molded resin, wherein the bridge-forming components include a first bridge that bridges a first semiconductor component and a second semiconductor component, and at least a portion of the surface of the molded resin after sealing has a recess between the gate-side boundary of the first bridge and the gate-opposite boundary thereof, and between the first semiconductor component and the second semiconductor component.

2. A power module as claimed in claim 1, characterized in that in the first bridge of said bridge forming component, the distance H1 between the underside of the bridge portion of said bridge forming component and the substrate and the thickness H2 of the molded resin at the upper part of the bridge portion have a relationship of H1 > H2, and the thickness H3 of the bridge portion has a relationship of H1 < H3.

3. A power module as claimed in claim 1, characterized in that in the projection plane of the first bridge of the bridge forming component, a recess is provided between a portion including the gate side boundary of the first bridge and not exceeding the opposite boundary of the gate, and between the first semiconductor component and the second semiconductor component.

4. A power module as claimed in claim 1, characterized in that in the vicinity of the projection surface of the entire bridge forming component, the surface of the molded resin after sealing has a recess corresponding to the entire surface in the vicinity of the projection surface.

5. A power module as claimed in claim 1, characterized in that a depression having an asymmetric cross-sectional shape is formed on the surface of said molded resin after sealing in the vicinity of the projection surface of said first bridge of said bridge forming component.

6. A power module as claimed in claim 1, characterized in that the surface of the molded resin after sealing has a curved recess without corners in the vicinity of the projection surface of the first bridge of the bridge forming part.

7. A power module as claimed in claim 1, characterized in that in the first bridge of the bridge forming components, the second bridge bridging the first semiconductor component and the substrate, and the third bridge bridging the second semiconductor component and the substrate, the end of the gate side boundary of each bridge cross section has a tapered surface or a protruding surface shape.

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