Semiconductor device, and method for manufacturing semiconductor device

Abstract

To reduce inductance.SOLUTION: A semiconductor device includes: a lead frame mounted with a semiconductor element; a DC terminal that is connected to the lead frame, of which a part is covered with a sealing resin and the balance projects from the sealing resin, and a metal plate which faces the DC terminal and is covered with the sealing resin.SELECTED DRAWING: Figure 3

Description

[Technical field]

[0001] The present invention relates to a semiconductor device and a method for manufacturing a semiconductor device. [Background technology]

[0002] Semiconductor devices including power modules are used in various industrial fields. There are many requirements for semiconductor devices, such as small size, low heat generation, low power consumption, and low inductance. Patent Document 1 discloses a power conversion device including a power semiconductor module having a plurality of input / output terminals arranged on one surface, a terminal cover having a partition formed of an insulating material and disposed between the input / output terminals, a circuit board for controlling the power semiconductor module, and a board support member for supporting the circuit board, the terminal cover being integrally provided on the board support member. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] JP 2017-112656 A Summary of the Invention [Problem to be solved by the invention]

[0004] The invention described in Patent Document 1 leaves room for improvement in terms of reducing inductance. [Means for solving the problem]

[0005] A semiconductor device according to a first aspect of the present invention comprises a lead frame on which a semiconductor element is mounted, a DC terminal connected to the lead frame and partially covered by sealing resin with the remainder protruding from the sealing resin, and a metal plate facing the DC terminal and covered by the sealing resin. A manufacturing method for a semiconductor device according to a second aspect of the present invention includes a preparation step of preparing a lead base in which a DC terminal to be connected to a lead frame and a metal plate are connected to each other by a tie bar; a bending step of bending the metal plate so that it faces the DC terminal; an arrangement step of arranging a semiconductor element and a conductive member connected to the semiconductor element on the lead frame; a covering step of covering the semiconductor element, the conductive member, and a portion of the DC terminal with a sealing resin; and a cutting step of cutting the tie bar, wherein the order of the bending step and the arrangement step can be reversed. Effect of the Invention

[0006] According to the present invention, the inductance can be reduced. [Brief description of the drawings]

[0007] [Figure 1] External perspective view of the power module [Diagram 2] Internal perspective view of the power module [Diagram 3] Front and side views of the power module [Figure 4] An enlarged view of the area circled by the dashed line in Figure 3. [Diagram 5] Three-dimensional view of metal plate [Figure 6] A close-up of the side view of the power module shown in Figure 3. [Figure 7] Diagram showing lead frame before processing [Figure 8] Diagram showing the manufacturing process of a power module [Figure 9] Diagram showing the effect of the power module DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0008] --Embodiment-- Hereinafter, an embodiment of a power module, which is a semiconductor device, will be described with reference to Figures 1 to 9. In this embodiment, for convenience of explanation, mutually orthogonal X, Y and Z axes are depicted in the drawings.

[0009] (composition) Fig. 1 is an external perspective view of a power module 100. The outer periphery of the power module 100 is covered by a case 400, and a part of the case 400 serves as a heat dissipation section 300 for dissipating heat. Although Fig. 1 only shows the heat dissipation section 300 arranged on the surface of the case 400 on the negative side of the Y axis, a heat dissipation section 300 is also arranged on the surface of the case 400 on the positive side of the Y axis.

[0010] The power module 100 includes a DC terminal 210, an AC terminal 220, a first control terminal 230, and a second control terminal 240. The DC terminal 210, the AC terminal 220, the first control terminal 230, and the second control terminal 240 are aligned in the X-axis direction and extend in the Z-axis direction. The DC terminal 210 is disposed between the first control terminal 230 and the second control terminal 240. A sealing resin 500 is disposed on the surface of the case 400 on the positive side of the Z-axis, and the negative sides of the DC terminal 210, the AC terminal 220, the first control terminal 230, and the second control terminal 240 are sealed by this sealing resin 500. The first control terminal 230 and the second control terminal 240 protrude more from the sealing resin 500 to the positive side of the Z-axis than the DC terminal 210.

[0011] FIG. 2 is an internal perspective view of the power module 100. The viewpoint of this figure is the same as that of FIG. 1, and the heat dissipation unit 300, the case 400, and the sealing resin 500 are removed. The DC terminal 210, the first control terminal 230, and the second control terminal 240 are formed by a part of the lead frame 200. The first semiconductor element 900-1, the second semiconductor element 900-2, the second conductive member 600, and the first conductive member 700 are arranged on the lead frame. The second conductive member 600 is also called an "AC lead", and the first conductive member 700 is also called an "N lead". In the following, the first semiconductor element 900-1 and the second semiconductor element 900-2 may be collectively called a "semiconductor element" 900.

[0012] The second conductive member 600 is connected to the AC terminal of the first semiconductor element 900-1, and the first conductive member 700 is connected to the negative terminal of the second semiconductor element 900-2. The DC terminals 210 are classified into a positive terminal 210P and a negative terminal 210N. The number and arrangement of the positive terminals 210P and the negative terminals 210N are not particularly limited, but for example, they are arranged in the order of the positive terminal 210P, the negative terminal 210N, the positive terminal 210P, and the negative terminal 210N. The potential of the negative terminal 210N is equal to the potential of the first conductive member 700. The potential of the AC terminal 220 is equal to the potential of the second conductive member 600.

[0013] 3 is a front view and a side view from a different perspective than FIG. 2. However, in this figure, the metal plate 800 is shown by hatching. The DC terminal 210 and the metal plate 800 are disposed facing each other in the Y-axis direction. In the front view in which the Y-axis positive side is the depth direction, the DC terminal 210 and the metal plate 800 overlap. In the side view in which the Y-axis positive side is to the right, it can be seen that there is a gap between the DC terminal 210 and the metal plate 800. Although not shown in FIG. 4, the first control terminal 230 and the second control terminal 240 are connected to the signal terminal of the semiconductor element 900 by, for example, wire bonding.

[0014] Fig. 4 is an enlarged view of the area circled by a dashed line in Fig. 3. However, in this figure, for convenience of explanation, the joint between the sealing resin 500 and the DC terminal 210 is highlighted by a dashed line. Note that in Fig. 4, the tip portion of the first control terminal 230 on the positive side of the Z axis is not shown for convenience of drawing. The joint between the sealing resin 500 and the DC terminal 210 has unevenness in the sealing resin 500 so that the creepage distance between adjacent terminals is long. Note that unevenness may be provided on a part of the end portion on the positive side of the Z axis of the metal plate 800 so as to roughly match this unevenness.

[0015] 5 is a three-view diagram of the metal plate 800. The metal plate 800 has, at the end on the positive side of the Z axis, a tie bar mark 810 which is a mark of the tie bar cut generated when the metal plate 800 is separated from the lead frame 200.

[0016] Fig. 6 is an enlarged side view of the power module 100 shown in Fig. 3. However, Fig. 6 also shows the heat dissipation unit 300. The metal plate 800 is electrically insulated from the lead frame 200 and the heat dissipation unit 300 by the sealing resin 500. The metal plate 800, like the second conductive member 600 and the first conductive member 700, is disposed on the negative side of the Y axis with respect to the lead frame 200.

[0017] If the metal plate 800 were arranged on the opposite side of the lead frame 200 to the second conductive member 600 and the first conductive member 700, i.e., on the positive side of the Y axis, the heat dissipation section 300 on the positive side of the Y axis would have to move to the positive side of the Y axis from its current state. Therefore, in the configuration shown in Fig. 6, it can be said that the size of the power module 100 in the Y axis direction can be reduced by having the metal plate 800, the second conductive member 600, and the first conductive member 700 on the same side of the lead frame 200. The metal plate 800 is embedded in the sealing resin 500 between the lead frame 200 and the heat dissipation section 300.

[0018] (Manufacturing method) A method for manufacturing the power module 100 will be described with reference to Figs. 7 and 8. Fig. 7 is a diagram showing a lead base 200B which is the lead frame 200 before processing. The lead base 200B is formed by pressing or laser processing a conductive metal plate. The lead base 200B includes an unprocessed DC terminal 210B, an unprocessed AC terminal 220B, an unprocessed first control terminal 230B, an unprocessed second control terminal 240B, and an unprocessed metal plate 800B which are portions which become the DC terminal 210, the AC terminal 220, the first control terminal 230, the second control terminal 240, and the metal plate 800.

[0019] The hatched areas indicate the unprocessed metal plate 800B, and the areas hatched mainly with dots are areas not required for the power module 100. The areas connected to the unprocessed metal plate 800B and the unprocessed DC terminals 210B are tie bars 850.

[0020] 8 is a diagram showing the manufacturing process of the power module 100. First, in a preparation step, the lead base 200B shown in FIG. 7 is prepared. In the first step, the tie bar 850 is bent in a predetermined direction, for example, toward the front side in the figure, so that the unprocessed metal plate 800B overlaps with the unprocessed DC terminal 210B. The first step is also called a bending step.

[0021] In the second step, the semiconductor element 900, the second conductive member 600, and the first conductive member 700 are mounted on the lead base 200B. The second conductive member 600 and the first conductive member 700 are mounted on the surface of the lead base 200B that faces the same direction as the unprocessed metal plate 800B, for example, the surface on the front side in the figure. A joining material such as solder is used for mounting them. Before proceeding to the next third step, unnecessary parts of the lead base 200B, that is, the areas indicated by hatching with dots, are removed. This removal may be included in the first step or the second step. The second step is also called a placement step.

[0022] In the third step, the sealing resin 500 is filled and hardened. This fixes the relative positions of the unprocessed metal plate 800B and the unprocessed DC terminal 210B. However, the tie bar 850 still exists at this stage. The third step is also called a covering step. In the fourth step, the tie bar 850 is cut. This fourth step forms the tie bar mark 810 shown in FIG. 5. The fourth step is also called a cutting step. After the fourth step, the sealing resin 500 is covered with the case 400 in which the heat dissipation part 300 is arranged, thereby completing the power module 100. Note that the first and second steps, i.e., the bending step and the arrangement step, may be performed in the reverse order.

[0023] (effect) 9 is a diagram showing the effect of the power module 100. Since the DC terminal 210 includes a positive electrode and a negative electrode, an eddy current E is generated in the metal plate 800 disposed opposite the DC terminal 210. Therefore, the power module 100 has an effect that the inductance of the DC terminal 210 is reduced by the metal plate 800, thereby reducing the surge voltage and loss.

[0024] Incidentally, the unprocessed metal plate 800B before processing the metal plate 800 was a region sandwiched between the unprocessed first control terminal 230B and the unprocessed second control terminal 240B as shown in FIG. 7. In order to form the lead frame 200 and each terminal from a rectangular plate material, the region of the unprocessed metal plate 800B must also be cut out. Therefore, it can be said that the unprocessed metal plate 800B would have been a region that would have been discarded if the inventors of the present application had not carefully considered it. Therefore, the power module 100 achieves a reduction in inductance by using a region that would have been discarded in the past.

[0025] According to the above-described embodiment, the following advantageous effects can be obtained. (1) The power module 100 includes a lead frame 200 on which a first semiconductor element 900-1 is mounted, a DC terminal 210 connected to the lead frame 200 and partially covered with a sealing resin 500 with the remaining portion protruding from the sealing resin 500, and a metal plate 800 facing the DC terminal 210 and covered with the sealing resin 500. Therefore, an eddy current E is generated as shown in FIG. 9, and the inductance can be reduced.

[0026] (2) Metal plate 800 has tie bar marks 810 that are marks left by cutting off tie bar 850 of lead frame 200. Therefore, it is possible to reduce the inductance of power module 100 by using areas that would have been wasted in the past.

[0027] (3) A plate-shaped conductive member is connected to the first semiconductor element 900-1. The first conductive member 700, the second conductive member 600, and the metal plate 800 are arranged on the same side of the lead frame, i.e., on the negative side of the Y axis. Therefore, as described with reference to FIG. 6, the size of the power module 100 in the Y axis direction can be reduced.

[0028] (4) The semiconductor elements 900 are a first semiconductor element 900-1 constituting an upper arm and a second semiconductor element 900-2 constituting a lower arm. The conductive members are a second conductive member 600 connected to an AC terminal of the first semiconductor element 900-1 and a first conductive member 700 connected to a negative terminal of the second semiconductor element 900-2. As shown in Fig. 6, the first conductive member 700, the second conductive member 600, and the metal plate 800 are arranged on the same side of the lead frame 200.

[0029] (5) The manufacturing method of the power module 100 includes a preparation step, a bending step, an arrangement step, a covering step, and a cutting step. In the preparation step, a lead base 200B is prepared in which a DC terminal 210 and a metal plate 800 connected to a lead frame 200 are connected to each other by a tie bar 850. In the bending step, the metal plate 800 is bent so as to face the DC terminal 210. In the arrangement step, a semiconductor element 900, a first conductive member 700, and a second conductive member 600 are arranged on the lead frame 200. In the covering step, the semiconductor element 900, the first conductive member 700, the second conductive member 600, and a part of the DC terminal 210 are covered with a sealing resin 500. In the cutting step, the tie bar 850 is cut. Note that the order of the bending step and the arrangement step can be reversed. Therefore, a power module 100 with reduced inductance can be manufactured.

[0030] (6) The lead base 200B includes the first control terminal 230 and the second control terminal 240. The DC terminal 210 is shorter than the first control terminal 230 and the second control terminal 240, and is disposed between the first control terminal 230 and the second control terminal 240. The metal plate 800 is surrounded by the DC terminal 210, the first control terminal 230, and the second control terminal 240. Therefore, it is possible to reduce the inductance of the power module 100 by using a region that was conventionally wasted.

[0031] (Variation 1) In the above-described embodiment, as shown in Fig. 6, the metal plate 800, the first conductive member 700, and the second conductive member 600 are all arranged on the same side of the lead frame 200, i.e., on the negative side of the Y axis. However, it is not an essential component that these three are on the same side, and they may be arranged separately. For example, the metal plate 800 may be arranged on the negative side of the Y axis from the lead frame 200, and the first conductive member 700 and the second conductive member 600 may be arranged on the positive side of the Y axis from the lead frame 200.

[0032] The present invention is not limited to the above-described embodiment and modifications, and other aspects that are conceivable within the scope of the technical concept of the present invention are also included within the scope of the present invention. [Explanation of symbols]

[0033] 100: Power module 200: Lead frame 200B: Lead bass 210: DC terminal 220: AC terminal 220B: AC terminal before processing 230: First control terminal 240: Second control terminal 500: Sealing resin 600: Second conductive member 700: First conductive member 800: Metal plate 800B:Metal plate before processing 810: Tie bar mark 850: Tie bar

Claims

1. A lead frame on which a semiconductor element is mounted; a DC terminal connected to the lead frame, a portion of which is covered with a sealing resin and a remaining portion of which protrudes from the sealing resin; a metal plate facing the DC terminal and covered with the sealing resin.

2. 2. The semiconductor device according to claim 1, The metal plate has a tie bar mark, which is a mark left by cutting off a tie bar of the lead frame.

3. 3. The semiconductor device according to claim 2, a plate-shaped conductive member is connected to the semiconductor element; The semiconductor device, wherein the conductive member and the metal plate are arranged on the same side of the lead frame.

4. 4. The semiconductor device according to claim 3, the semiconductor element is a first semiconductor element constituting an upper arm and a second semiconductor element constituting a lower arm, the conductive member is a second conductive member connected to an AC terminal of the first semiconductor element, and a first conductive member connected to a negative terminal of the second semiconductor element, a semiconductor device, wherein the first conductive member, the second conductive member, and the metal plate are arranged on the same side of the lead frame.

5. a preparation step of preparing a lead base in which a DC terminal to be connected to a lead frame and a metal plate are connected to each other by a tie bar; a bending step of bending the metal plate so as to face the DC terminal; a placement step of placing a semiconductor element and a conductive member connected to the semiconductor element on the lead frame; a covering step of covering the semiconductor element, the conductive member, and a portion of the DC terminal with a sealing resin; A cutting step of cutting the tie bar, The method for manufacturing a semiconductor device, wherein the bending step and the placement step are interchangeable in order.

6. 6. The method for manufacturing a semiconductor device according to claim 5, the lead base further includes a control terminal; The DC terminal is shorter than the control terminal and is disposed between the control terminals, The metal plate is surrounded by the DC terminal and the control terminal.

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