Electronic module and production method for electronic module

Abstract

This electronic module 1 comprises a substrate 10, electronic elements 20a–20h that are provided on the substrate 10, an outer lead frame 70 that is provided above the substrate 10 so as to be separated from the substrate 10 and has external terminals T1–T4 formed at end parts, and an inner lead frame 60 that is provided between the substrate 10 and the outer lead frame 70. The inner lead frame 60 is thinner than the outer lead frame 70.　This electronic module makes it possible to use a lead frame to form fine internal wiring.

Description

Electronic Module and Method for Manufacturing Electronic Module

[0001] The present invention relates to an electronic module and a method for manufacturing an electronic module.

[0002] Conventionally, there has been known an electronic module including a lead frame spaced apart from a substrate and disposed above the substrate (see, for example, Patent Document 1).

[0003] For example, as shown in FIG. 12, an electronic module 900 described in Patent Document 1 includes a substrate 910, an electronic element 920 disposed on the substrate 910, and a lead frame 960 spaced apart from the substrate 910 and disposed above the substrate 910. Pin terminals are erected on the substrate 910 so as to penetrate through the lead frame 960.

[0004] International Publication No. 2020 / 208741

[0005] Incidentally, in the conventional electronic module 900, it is conceivable to configure the end portion of the lead frame as an external terminal. In this case, however, the lead frame needs to be relatively thick, which poses a problem that it is difficult to form fine internal wiring using the lead frame.

[0006] Accordingly, the present invention has been made to solve the above problem, and an object of the present invention is to provide an electronic module capable of forming fine internal wiring using a lead frame. Another object of the present invention is to provide a method for manufacturing an electronic module that manufactures such an electronic module.

[0007] The electronic module of the present invention includes: a substrate; an electronic element disposed on the substrate; an outer lead frame spaced apart from the substrate and disposed above the substrate, an end of the outer lead frame constituting an external terminal; and an inner lead frame disposed between the substrate and the outer lead frame, wherein the inner lead frame is thinner than the outer lead frame.

[0008] The present invention relates to a method for manufacturing an electronic module, comprising: a substrate preparation step of preparing a substrate on which electronic elements are arranged; an inner lead frame arrangement step of arranging an inner lead frame connected to a frame above the substrate; an outer lead frame arrangement step of arranging an outer lead frame connected to a frame above the inner lead frame, spaced apart from the substrate and the inner lead frame; further comprising a pin terminal press-fitting step of press-fitting pin terminals into through holes formed in a part of the inner lead frame; and further comprising a frame separation step of separating the inner lead frame from the frame after the inner lead frame arrangement step.

[0009] According to the electronic module of the present invention, it comprises an outer lead frame whose ends constitute external terminals, and an inner lead frame disposed between the substrate and the outer lead frame. Since the inner lead frame is thinner than the outer lead frame, it is possible to form a thicker outer lead frame that constitutes the external terminals, while using the thin inner lead frame to form fine internal wiring.

[0010] The electronic module manufacturing method of the present invention makes it possible to manufacture the electronic module described above. Furthermore, the electronic module manufacturing method of the present invention includes a pin terminal press-fitting step in which pin terminals are press-fitted into through holes formed in a part of the inner lead frame so that their tips reach the substrate, thereby allowing the pin terminals to be stably positioned by the inner lead frame. Moreover, the electronic module manufacturing method of the present invention includes a frame separation step in which the inner lead frame is separated from the frame, so that the inner lead frame can be stably fixed using the frame during the manufacturing process, and by stably fixing the inner lead frame, it becomes easier to press-fit the pin terminals into the through holes.

[0011] This is a perspective view showing an electronic module 1 according to an embodiment. This is a diagram illustrating the outer lead frame 70. This is a cross-sectional view illustrating the electronic module 1 according to an embodiment. This is a diagram illustrating the inner lead frame 60. This is a diagram illustrating semiconductor elements 20a to 20h, signal substrates 30a to 30d, gate pin terminals 40a to 40h, and sense pin terminals 50a to 50d. This is a diagram illustrating gate wiring sections 34a to 34h and sense wiring sections 36a to 36d. This is a cross-sectional view illustrating the long connector 62. This is a plan view illustrating the inner lead frame arrangement process. This is a plan view illustrating the outer lead frame arrangement process. This is a plan view illustrating the frame separation process. This is a plan view illustrating the resin encapsulation process. This is a cross-sectional view illustrating a conventional electronic module 900.

[0012] The electronic module and method for manufacturing the electronic module of the present invention will be described below based on the embodiments shown in the figures. Note that the embodiments described below do not limit the invention as defined in the claims. Furthermore, not all of the elements and combinations thereof described in the embodiments are necessarily essential to the solution of the present invention.

[0013] [Embodiment] 1. Configuration of the Electronic Module 1 According to the Embodiment As shown in Figure 1, the electronic module 1 according to the embodiment is resin-sealed with molded resin 90, with external terminals T1, T2, and T3 protruding from one side surface, and external terminal T4 protruding from the other side surface opposite to the first side surface. In addition, gate pin terminals 40a to 40h, sense pin terminals 50a to 50d, and other pin terminals 46 protrude from one main surface.

[0014] To simplify the explanation below, the direction from the side with external terminal T1 to the side with external terminal T3 (among the sides without external terminals T1 to T4) will be defined as the +X direction, the direction from the side with external terminal T4 to the side with external terminals T1 to T3 will be defined as the +Y direction, and the direction from the opposite main surface of one main surface to the main surface on which the pin terminals are located will be defined as the +Z direction.

[0015] As shown in Figures 2 to 6, the electronic module 1 according to this embodiment comprises a substrate 10, semiconductor elements 20a to 20h as electronic elements, signal boards 30a to 30d, gate pin terminals 40a to 40h, sense pin terminals 50a to 50d, an inner lead frame 60, an outer lead frame 70, and connecting members 80 and 81. In the electronic module 1 according to this embodiment, semiconductor elements 20a to 20d are connected in parallel, and semiconductor elements 20e to 20h are also connected in parallel, forming a half-bridge circuit in which semiconductor elements 20a to 20d and semiconductor elements 20e to 20h are connected in series.

[0016] In the electronic module 1 according to this embodiment, the main current is connected from the external terminal T2 to the power wiring section 14b of the substrate 10 via the internal connection terminal 75, as shown by the dashed line in Figure 3, passes below the signal substrates 30c and 30d, and flows to the drain electrodes of the semiconductor elements 20e to 20h. The main current then passes through the inside of the semiconductor elements 20e to 20h, from the source electrode through the inner lead section 61, the internal connection terminal 64, the power wiring section 14a, the semiconductor elements 20a to 20d, the long connector 62, the internal connection terminal 72, and the first outer lead section 71, and flows to the external terminals T1 and T3. The external terminal T4 is connected to the power wiring section 14a and is configured as the midpoint terminal between the semiconductor elements 20e to 20h and the semiconductor elements 20a to 20d.

[0017] As shown in Figures 3, 5, and 6, the substrate 10 is a DCB substrate (Direct Copper Bonding substrate) having an insulating substrate 12 (ceramic substrate), power wiring sections 14a and 14b made of metal plates (for example, copper plates) formed on one side (top surface) of the insulating substrate 12, and a heat dissipation metal plate 16 formed on the other side (bottom surface) of the insulating substrate 12. In this embodiment, a DCB substrate was used as the substrate 10, but any suitable substrate such as a printed circuit board may be used.

[0018] As shown in Figure 6, the two power wiring sections 14a and 14b are arranged side by side in the Y direction. Semiconductor elements 20a to 20d are arranged on power wiring section 14a along the -X direction, and rectangular signal boards 30a and 30b are arranged side by side in the X direction on the external terminal T4 side (-Y direction side) of the semiconductor elements 20a to 20d. Semiconductor elements 20e to 20h are arranged on power wiring section 14b along the -X direction, and rectangular signal boards 30c and 30d are arranged side by side in the X direction on the external terminal T2 side (+Y direction side) of the semiconductor elements 20e to 20h.

[0019] As shown in Figures 3, 5, and 6, each semiconductor element 20a to 20h is a vertical MOSFET (Metal-Oxide-Semiconductor Field-Effect Transistor) with source electrode portions 22a to 22h (main electrodes), gate electrode portions 24a to 24h, and sense electrode portions 26a to 26h formed on the front surface (the side opposite to the substrate 10), and a drain electrode (not shown) formed across the entire back surface (the side facing the substrate 10).

[0020] The source electrode portions 22a to 22h occupy most of the surface of the semiconductor elements 20a to 20h, and as shown in Figures 5 and 6, they are divided into two parts along the shorter direction (+X direction) when viewed from above.

[0021] In semiconductor elements 20a to 20d, gate electrode portions 24a to 24d and sense electrode portions 26a to 26d are arranged side by side along the outer edge on the -Y direction side of source electrode portions 22a to 22d, that is, on the signal substrate 30a and 30b side. The gate electrode portions 24a to 24d are formed near the center of the outer edge. There are two sense electrode portions 26a to 26d, and they are arranged side by side so as to sandwich the gate electrode portions 24a to 24d.

[0022] In the semiconductor elements 20e to 20h, the gate electrode portions 24e to 24h and the sense electrode portions 26e to 26h are arranged side by side along the outer edge on the +Y direction side of the source electrode portions 22e to 22h, that is, on the signal substrate 30c and 30d side. The gate electrode portions 24e to 24h are formed near the center of the outer edge, and there are two sense electrode portions 26e to 26h, which are arranged side by side so as to sandwich the gate electrode portions 24e to 24h.

[0023] The signal boards 30a to 30d are substantially rectangular substrates having insulating substrates 32a to 32d, gate wiring sections 34a to 34h and sense wiring sections 36a to 36d formed on one side (top surface) of the insulating substrates 32a to 32d, and a back metal 38 formed on the other side (bottom surface) of the insulating substrate 32. The signal boards 30a to 30d only need to be able to insulate one side from the other, and for example, glass epoxy substrates can be used. The signal boards 30a to 30d have a rectangular shape and are arranged so that their longitudinal direction is along the X direction, with signal boards 30a and 30b arranged alongside semiconductor elements 20a to 20d, and signal boards 30c and 30d arranged alongside semiconductor elements 20e to 20h. The signal boards 30a and 30b are placed on the power wiring section 14a, and the signal boards 30c and 30d are placed on the power wiring section 14b.

[0024] As shown in Figures 5 and 6, the sense wiring sections 36a to 36d extend from near the center of each signal board 30a to 30d to the vicinity of the sense electrode sections 26a to 26d of each semiconductor element, and are connected to one of the sense electrode sections 26a and 26b via a connecting member 81. Sense pin terminals 50a to 50d are erected near the center of each of the sense wiring sections 36a to 36d.

[0025] The gate wiring sections 34a to 34h are arranged in pairs on each signal board, and are positioned opposite the sense wiring sections 36a to 36d. The gate wiring sections 34a to 34h extend to the vicinity of the gate electrode sections 24a to 24h of the semiconductor elements 20a to 20d and are connected to the gate electrode sections 24a to 24h via connecting members 80. In addition, gate pin terminals 40a to 40h are erected at predetermined positions on the gate wiring sections 34a to 34h.

[0026] The gate pin terminals 40a to 40h and the sense pin terminals 50a to 50d are columnar members made of a conductive material (e.g., a metal material), with their tips exposed to the outside of the molded resin 90, thus forming terminals. Each of the gate pin terminals 40a to 40h (and the sense pin terminals 50a to 50d) has a main body portion 41 (51) and a ring-shaped flange portion 42 (52) provided at an intermediate position in the height direction, as shown in Figure 3. Below each flange portion 42 (52), a pin terminal fixing portion 63, which is part of the lead frame, is positioned, and the gate pin terminals 40a to 40h (and the sense pin terminals 50a to 50d) are joined to the pin terminal fixing portion 63 via the flange portion 42 (52).

[0027] The wiring length from each gate pin terminal to the gate electrode of the semiconductor element via the gate wiring section and connecting member 80 is the same in all cases. Furthermore, each gate wiring section is arranged symmetrically with respect to a straight line passing through the sense pin terminal (a straight line passing through the center of the signal board 30).

[0028] The wiring length from each sense pin terminal to the sense electrode portion of the semiconductor element via the sense wiring section and connecting member 81 is the same in all cases. Furthermore, each sense wiring section is arranged symmetrically with respect to a straight line passing through the sense pin terminal (a straight line passing through the center of the signal board 30). As shown in Figure 6, there is a region between each sense pin terminal and the connecting member 81 where the sense wiring section 36 is separated, and this separated region is connected via a resistor R.

[0029] In the electronic module according to this embodiment, one semiconductor element group is formed by two semiconductor elements, one signal board, two gate pin terminals, one sense pin terminal, and connecting members 80 and 81. In this embodiment, four semiconductor element groups are formed: semiconductor element group G1 related to semiconductor elements 20a and 20b, semiconductor element group G2 related to semiconductor elements 20c and 20d, semiconductor element group G3 related to semiconductor elements 20e and 20f, and semiconductor element group G4 related to semiconductor elements 20g and 20h. Groups G1 to G4 all have the same shape and are configured to be symmetrical with respect to a line passing through the sense pin terminals 50a to 50d.

[0030] Groups G1 to G4 are positioned symmetrically with respect to a line passing through the center of the substrate 10. Specifically, Group G1 and Group G2, and Group G3 and Group G4 are positioned symmetrically with respect to a line passing through the center of the substrate 10 and extending vertically in Figure 5; Group G1 and Group G3, and Group G2 and Group G4 are positioned symmetrically with respect to a line passing through the center of the substrate 10 and extending horizontally in Figure 7; and Group G1 and Group G4, and Group G2 and Group G3 are positioned symmetrically with respect to the center of the substrate 10.

[0031] As shown in Figures 3 and 4, an inner lead frame 60 is positioned above the substrate 10. The inner lead frame 60 has an inner lead portion 61, a long connector 62, and a pin terminal fixing portion 63, and the inner lead portion 61, the long connector 62, and the pin terminal fixing portion 63 are formed at the same height. The inner lead frame 60 is thinner than the outer lead frame 70, which will be described later.

[0032] Each component of the inner lead frame 60 is provided with a lead portion L extending in either the +X direction or the -X direction. During the manufacturing process, the lead portions L constituted suspension leads that connected to the frame portion 65 (see Figure 8). The tips of the lead portions L are all located inside the molded resin 90.

[0033] As shown in Figures 3 and 4, the inner lead portion 61 is connected to the source electrode portions 22e to 22h of the semiconductor elements 20e to 20h. The inner lead portion 61 extends toward the power wiring portion 14a and is connected to the power wiring portion 14a via the internal connection terminal 64.

[0034] As shown in Figures 4 and 7, the elongated connector 62 is connected to the source electrode portions 22a to 22d of the semiconductor elements 20a to 20d. The elongated connector 62 extends along the X direction when viewed in plan, and has a shape that protrudes in the -Z direction at the position where it overlaps with the semiconductor elements 20a to 20d.

[0035] The first outer lead portion 71 and the long connector 62, which will be described later, are connected by an internal connection terminal 72. The internal connection terminal 72 is located in a position that does not overlap with the positions of the semiconductor elements 20a to 20d when viewed in plan view. Specifically, it is located midway between the electrodes of adjacent semiconductor elements 20a and 20b, and 20c and 20d when viewed in plan view.

[0036] The pin terminal fixing portion 63 is positioned at an intermediate position between each gate pin terminal 40a to 40h and each sense pin terminal 50a to 50d. Each pin terminal fixing portion 63 has a through hole through which the pin terminal passes.

[0037] As shown in Figure 2, an outer lead frame 70 is positioned above the substrate 10 and the inner lead frame 60. The outer lead frame 70 has a first outer lead portion 71, a second outer lead portion 73 (external terminal T2), and a third outer lead portion 74 (external terminal T4), each formed at the same height. The first outer lead portion 71 of the outer lead frame 70 overlaps with the inner lead frame 60 (specifically, the inner lead portion 61) in a planar view, and as shown in Figure 3, current flows in opposite directions (in the -Y direction for the inner lead portion 61 and in the +Y direction for the first outer lead portion 71) at relatively close positions.

[0038] The first outer lead portion 71 is a flat, roughly U-shaped member, with an elongated hole formed in the region where the internal connection terminal 64 is formed (the region where the inner lead portion 61 and the power wiring portion 14a are connected). The first outer lead portion 71 extends in the +Y direction on both the +X and -X sides, and extends to the outside of the molded resin 90. The portions extending to the outside of the molded resin 90 constitute the external terminals T1 and T3, respectively (see Figure 1).

[0039] The second outer lead portion 73 is connected to the power wiring portion 14a via an internal connection terminal 75, extends in the +Y direction, and extends to the outside of the molded resin 90. The portion extending to the outside of the molded resin 90 constitutes the external terminal T2.

[0040] The third outer lead portion 74 is connected to the power wiring portion 14b via an internal connection terminal 76, extends in the -Y direction, and extends to the outside of the molded resin 90. The portion extending to the outside of the molded resin 90 constitutes the external terminal T4.

[0041] The connecting members 80 and 81 are formed by cutting and bending a plate-shaped conductive member.

[0042] 2. Method for Manufacturing the Electronic Module 1 According to the Embodiment Next, a method for manufacturing the electronic module 1 according to the embodiment will be described. The method for manufacturing the electronic module 1 according to the embodiment includes a substrate preparation step, an inner lead frame placement step, a pin terminal press-fitting step, an outer lead frame placement step, a frame separation step, and a resin sealing step.

[0043] (1) Substrate preparation process First, prepare the substrate 10 on which the semiconductor elements 20a to 20h are arranged. Specifically, prepare the substrate 10 on which the semiconductor elements 20a to 20d are arranged on the power wiring section 14a and the semiconductor elements 20e to 20h are arranged on the power wiring section 14b (see Figure 6).

[0044] (2) Inner lead frame arranging step Next, the inner lead frame 60 connected to the frame portion 65 is arranged above the substrate 10 in a state where the frame portion 65 is supported by a predetermined jig (see FIG. 8). Then, the inner lead frame 60 is positioned such that the inner lead portions 61 are arranged on the source electrodes of the semiconductor elements 20e to 20h via a conductive bonding material, and the elongated connectors 62 are arranged on the source electrodes of the semiconductor elements 20a to 20d via the conductive bonding material.

[0045] At this time, as shown in the region surrounded by the broken line L in FIG. 8, the frame portion 65 and each component of the inner lead frame 60 (the inner lead portion 61, the elongated connector 62, the pin terminal fixing portion 63, etc.) are connected to the frame portion 65 via suspension pins (lead portions).

[0046] Next, pin terminals (gate pin terminals 40a to 40h and sense pin terminals 50a to 50d) are press-fitted into through holes formed in a part of the inner lead frame 60. Further, the internal connection terminal 64 is also press-fitted. At this time, the tips of the pin terminals and the internal connection terminal 64 are connected to the substrate 10 via the conductive bonding material. Note that the inner lead frame 60 with the pin terminals and the internal connection terminal 64 press-fitted in advance may be arranged above the substrate 10.

[0047] (3) Outer lead frame arranging step Next, as shown in FIG. 9, the outer lead frame 70 connected to the frame portion 77 is spaced apart from the substrate 10 and the inner lead frame 60 above the inner lead frame 60, and arranged in a state where the frame portion 77 is supported by a predetermined jig. Specifically, the outer lead frame 70 is arranged such that the internal connection terminals 72 are respectively located at an intermediate position between the semiconductor element 20a and the semiconductor element 20b and at an intermediate position between the semiconductor element 20c and the semiconductor element 20d on the elongated connector 62, and the outer lead frame 70 is at a predetermined position where it does not come into contact with each pin terminal.

[0048] (4) Frame separating step Next, the hanging pins connecting the frame portion 65 of the inner lead frame 60 to each constituent component are cut, and each constituent component of the inner lead frame 60 is separated from the frame portion 65 (see region A in FIG. 10). The cut hanging pins form the lead portions L. Next, these members are heated to melt the conductive bonding material, bond each member, and form an assembly.

[0049] (5) Resin sealing step Next, the assembly is placed in a resin sealing mold (not shown) and filled with molding resin 90 to perform resin sealing (see FIG. 11). The resin sealing mold has an upper mold and a lower mold, and a resin sealing cavity is formed by a recess provided in the upper mold and a recess provided in the lower mold. Further, the upper mold has pin terminal accommodation holes for accommodating pin terminals, and a slide core provided on the inner circumferential surface of the pin terminal accommodation holes. Before resin sealing, the slide core is moved to block the portion that becomes the external terminal of the pin terminal from the resin sealing cavity, thereby preventing the pin terminal from being sealed with resin.

[0050] In the resin sealing step, the substrate 10 is placed in the recess of the lower mold, and the upper mold is placed on the lower mold while accommodating each pin terminal in the corresponding pin terminal accommodation hole. This allows the assembly to be accommodated in the resin sealing cavity. Next, after moving the slide core to block the portion that becomes the external terminal of the pin terminal from the resin sealing cavity before resin sealing, the cavity is filled with resin. Thus, the assembly is resin-sealed. Next, the hanging pins connecting the frame portion 77 of the outer lead frame 70 to each constituent component are cut, and each constituent component of the outer lead frame 70 is separated from the frame portion 77. In this way, the electronic module 1 can be manufactured.

[0051] 3. Effects of the Electronic Module 1 According to the electronic module 1 according to the embodiment, it comprises an outer lead frame 70 whose ends constitute external terminals T1 to T4, and an inner lead frame 60 disposed between the substrate 10 and the outer lead frame 70. Since the inner lead frame 60 is thinner than the outer lead frame 70, it is possible to form a thicker outer lead frame 70 that constitutes the external terminals, while using the thin inner lead frame 60 to form fine internal wiring.

[0052] Incidentally, it is generally known that when two conductive plates are placed in close proximity facing each other so as to overlap, and current is passed through the two conductive plates in opposite directions, mutual inductance is generated, canceling out the inductance of the conductive plates. In the electronic module 1 according to this embodiment, the outer lead frame 70 and the inner lead frame 60 overlap when viewed in plan, so the inductance can be canceled out by passing current in opposite directions through the outer lead frame 70 and the inner lead frame 60.

[0053] Furthermore, according to the embodiment of the electronic module 1, it is equipped with pin terminals (gate pin terminals 40a to 40h and sense pin terminals 50a to 50d) erected on a substrate, and a pin terminal fixing portion 63 having a through hole through which the pin terminals pass is formed in a part of the inner lead frame 60, and since the pin terminal fixing portion 63 is positioned at the same height as the inner lead frame 60, the pin terminals can be fixed to the inner lead frame 60 (pin terminal fixing portion 63), and the pin terminals can be erected stably.

[0054] Furthermore, according to the electronic module 1 of this embodiment, the end portion (lead portion L) of the inner lead frame 60 is located inside the molded resin 90, and internal wiring such as the inner lead portion 61 and the pin terminal fixing portion 63 can be formed using the lead frame, so that each component can be arranged relatively easily as a whole.

[0055] Furthermore, according to the electronic module 1 of this embodiment, multiple semiconductor elements 20e to 20h are arranged side by side and connected in parallel to each other. This reduces the current flowing through each semiconductor element and the amount of heat generated. As a result, it is possible to create an electronic module that can use high currents and an electronic module with a relatively long lifespan due to the reduced burden on the semiconductor elements.

[0056] Furthermore, according to the electronic module 1 of this embodiment, the outer lead frame 70 and the long connector 62 are connected by an internal connection terminal 72. The internal connection terminal 72 is positioned midway between adjacent semiconductor elements 20a, 20b (and 20c, 20d) when viewed in plan. As a result, current from each semiconductor element flows evenly to the long connector 62 and the first outer lead portion 71, preventing localized current concentration and thus preventing localized heat generation.

[0057] Furthermore, according to the electronic module 1 of this embodiment, the electronic module 1 constitutes a half-bridge circuit, and the outer lead frame 70 and inner lead frame 60 constitute the current path through which the main current of the half-bridge circuit flows. Therefore, reverse current can be passed through the outer lead frame 70 and inner lead frame 60, thereby reducing impedance.

[0058] According to the manufacturing method of the electronic module according to the embodiment, the electronic module 1 according to the embodiment can be manufactured. Furthermore, the manufacturing method of the electronic module according to the embodiment includes a pin terminal press-fitting step in which pin terminals are press-fitted into through holes formed in a part of the inner lead frame 60 so that their tips reach the substrate 10, so that the pin terminals can be stably positioned by the inner lead frame 60. Moreover, the manufacturing method of the electronic module according to the embodiment includes a frame portion separation step in which the inner lead frame 60 is separated from the frame portion 65, so that the inner lead frame 60 can be stably fixed using the frame portion 65 during the manufacturing process, and by stably fixing the inner lead frame 60, it becomes easier to press-fit the pin terminals into the through holes.

[0059] Although the present invention has been described above based on the embodiments described above, the present invention is not limited to the embodiments described above. It can be implemented in various forms without departing from the spirit of the invention, and for example, the following modifications are also possible.

[0060] (1) The positions, connections, number, circuit configuration, terminals, etc. described in the above embodiments are illustrative examples and can be changed within the scope that does not impair the effects of the present invention.

[0061] (2) In the above embodiment, an inner lead frame 60 having an inner lead portion 61, a long connector 62, and a pin terminal fixing portion 63 was used, but the present invention is not limited thereto. An inner lead frame without any of the inner lead portion 61, the long connector 62, and the pin terminal fixing portion 63 may be used, or an inner lead having other components may be used.

[0062] (3) In the above embodiment, an inner lead frame 60 thinner than the outer lead frame 70 was used, but the present invention is not limited thereto. If an internal circuit can be constructed, an inner lead frame 60 having the same thickness as the outer lead frame 70 may be used.

[0063] (4) In the above embodiments, semiconductor elements, particularly vertical MOSFETs, were used as electronic elements, but the present invention is not limited thereto. Horizontal MOSFETs, that is, horizontal MOSFETs with drain electrodes formed on the side opposite to the substrate, may also be used. Furthermore, in addition to MOSFETs, transistors other than MOSFETs, such as IGBTs, thyristors, and triacs, may also be used. Moreover, electronic elements other than semiconductors (for example, capacitors, inductors, etc.) may also be used.

[0064] (5) In the above embodiment, one sense pin terminal and two gate pin terminals are provided on one signal board, but the present invention is not limited thereto. There may be two sense pin terminals or one gate pin terminal.

[0065] (6) In each of the above embodiments, two semiconductor elements are connected to one signal board, but the present invention is not limited thereto. Three or more semiconductor elements may be connected to one signal board. In order to make the wiring length between the gate pin terminal and the gate electrode portion of each semiconductor element equal, it is preferable that the number of semiconductor elements be even.

[0066] (7) In each of the above embodiments, two of the four parallel-connected semiconductor elements are connected to one signal board, but the present invention is not limited thereto. All four parallel-connected semiconductor elements may be connected to one signal board.

[0067] (8) In the above embodiments, all of the multiple electronic elements were the same electronic element (semiconductor element), but the present invention is not limited thereto. Different types of electronic elements may be used as the multiple electronic elements.

[0068] 1...Electronic module, 10...Substrate, 20a-20h...Semiconductor element, 40a-40h...Gate pin terminals, 46...Pin terminal, 50a-50d...Sense pin terminals, 60...Inner lead frame, 62...Long connector, 63...Pin terminal fixing part, 65...Frame part (of inner lead frame), 70...Outer lead frame, 77...Frame part (of outer lead frame), 90...Molded resin

Claims

1. An electronic module comprising: a substrate; electronic elements disposed on the substrate; an outer lead frame disposed above the substrate and spaced apart from the substrate, with its ends constituting external terminals; and an inner lead frame disposed between the substrate and the outer lead frame, wherein the inner lead frame is thinner than the outer lead frame.

2. The electronic module according to claim 1, characterized in that the outer lead frame and the inner lead frame overlap when viewed in plan.

3. The electronic module according to claim 1 or 2, further comprising pin terminals erected on the substrate, wherein a part of the inner lead frame has a pin terminal fixing portion having a through hole through which the pin terminals pass, and the pin terminal fixing portion is positioned at the same height as the inner lead frame.

4. The electronic module according to claim 1 or 2, characterized in that the substrate, the electronic element, the outer lead frame, and the inner lead frame are sealed in a molded resin, and the ends of the inner lead frame are located within the molded resin.

5. The electronic module according to claim 1 or 2, characterized in that a plurality of the electronic elements are arranged in a row and connected in parallel to one another.

6. The electronic module according to claim 1 or 2, characterized in that a plurality of electronic elements connected in parallel to each other are connected by long connectors, the outer lead frame and the long connectors are connected by internal connection terminals, and the internal connection terminals are positioned at an intermediate position between adjacent electronic elements when viewed in plan.

7. The electronic module according to claim 1 or 2, wherein the electronic module constitutes a half-bridge circuit, and the outer lead frame and the inner lead frame constitute a current path through which the main current of the half-bridge circuit flows.

8. A method for manufacturing an electronic module according to claim 1 or 2, comprising: a substrate preparation step of preparing a substrate on which electronic elements are arranged; an inner lead frame arrangement step of arranging an inner lead frame connected to a frame above the substrate; an outer lead frame arrangement step of arranging an outer lead frame connected to a frame above the inner lead frame, spaced apart from the substrate and the inner lead frame; further comprising a pin terminal press-fitting step of press-fitting pin terminals into through holes formed in a part of the inner lead frame; and further comprising a frame separation step of separating the inner lead frame from the frame after the inner lead frame arrangement step.

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