Power module

Abstract

Power module (100), comprising: a base plate (10) having a first surface; a plurality of electrode plates (21, 22) provided on the first surface; a semiconductor chip (30) provided on the first surface; a wire (40) connected to the semiconductor chip (30) and one of the electrode plates (21, 22); a metal element (50) connected to one of the electrode plates (21, 22); a terminal plate (61) having a bonding part (61a), a curved part (61b), a first intermediate part (61c), a second intermediate part (61d), a third intermediate part (61e), and a lead-out part (61e), wherein the bonding part (61a) is in contact with and extends along an upper surface of the metal member (50), the curved part (61b) is curved upward from the bonding part (61a), the first intermediate part (61c) extends upward from the curved part (61b), the second intermediate part (61d) extends from the first intermediate part (61c) in a direction parallel to the first surface, the third intermediate part (61e) extends upward from the second intermediate part (61d), and the lead-out part (61e) is led outward from the third intermediate part (61e); a first resin layer (71), wherein a connecting part (40b) of the wire (40) and the semiconductor chip (30) are arranged inside the first resin layer (71); and a second resin layer (72) provided on the first resin layer (71), wherein the curved part (61b) is arranged inside the second resin layer (72), wherein an elastic modulus of the second resin layer (72) is lower than an elastic modulus of the first resin layer (71), wherein a length between the first surface and a bottom of the bonding part (61a) is greater than a length between the first surface and the connecting part (40b), wherein a thermal expansion coefficient of the first resin layer (71) is smaller than a thermal expansion coefficient of the second resin layer (72), the connecting plate (61) is formed by bending a plate, and where a wedge-shaped gap is formed between the underside of the curved part (61b) of the connecting plate (61) and the upper side of the metal element (50), and the second resin layer (72) enters the gap.

Description

FIELD OF THE INVENTION

[0001] One embodiment relates to a power module. BACKGROUND

[0002] A power module has been developed in which a semiconductor chip for power control is provided in a package, and electrical power is input and output from and to the outside of the package by connecting terminal boards to the semiconductor chip. In such a power module, the package is filled with an insulating gel material to maintain the insulated state of the internal circuitry, terminal boards, etc. It is expected that the conduction amount of power modules will further increase thereafter, and countermeasures for heat generation due to conduction will be difficult. Such power modules are shown and described, for example, in DE 11 2008 003 425 T5, US 10 304 788 B1, DE 10 2011 084 803 A1, and DE 10 2017 115 879 A1. BRIEF DESCRIPTION OF THE DRAWINGS Fig. 1 is a perspective view showing a power module according to an embodiment; Fig. 2A is a partial cross-sectional view showing the power module according to the embodiment; Fig. Figure 2B is a partially enlarged cross-sectional view of Fig. 2A; Fig. 3A is a partially enlarged cross-sectional view showing a power module according to Comparative Example 1; and Fig. 3B is a partial cross-sectional view showing a power module according to Comparative Example 2. DETAILED DESCRIPTION

[0003] A power module according to the invention has the features of patent claim 1. Advantageous further developments are described in the further claims.

[0004] The embodiment is described below with reference to the accompanying drawings.

[0005] The drawings are schematic and conceptual, and the relationships between the thickness and width of parts, the proportions between parts, etc., are not necessarily the same as the actual values. Dimensions and proportions may be represented differently among the drawings, even for identical parts. In the description and drawings, components similar to those already described or shown in a previous drawing are marked with the same reference symbols, and detailed descriptions are omitted where appropriate. (Embodiment)

[0006] Fig. Fig. 1 is a perspective view showing a power module according to the embodiment. A top part 11c of a housing 11 described below is shown in Fig. 1 not shown. Fig. 2A is a partial cross-sectional view showing the power module according to the embodiment. Fig. Figure 2B is a partially enlarged cross-sectional view of Fig. 2A.

[0007] As in Fig. As shown in Figure 1, the general shape of the power module 100 of the embodiment is a substantially rectangular parallelepiped. The housing 11 is provided in the power module 100. The housing 11 essentially forms the outer shape of the power module 100.

[0008] As in Fig. 1 and the Fig. 2A and Fig. 2B, the power module 100 mainly includes a base plate 10 inserted into a bottom side part 11a of the case 11, a plurality of electrode plates 21 and 22 provided in a plane on a top surface 10A which is a first surface of the base plate 10, a plurality of semiconductor chips 30 having top surface electrodes 30b, a first resin layer 71 and a second resin layer 72 filling the interior of the power module 100, a plurality of terminal plates 61, 62 and 63 for external connection, and a plurality of internal wiring terminal plates (hereinafter also generally referred to simply as the “terminal plate 60”).

[0009] In the power module 100, electric power flows in from an external power supply through the terminal boards 62 and 63 for input, the electric power is converted by the plurality of semiconductor chips 30, and the converted electric power is output to the outside of the power module 100 through the terminal board 61 for output.

[0010] For the sake of simplicity of description, a direction along the long side of the first surface 10A is used in the Fig. 2A and Fig. 2B is taken as an X direction. A direction perpendicular to the X direction and along the short side of the first surface 10A is taken as a Y direction. A direction perpendicular to the XY plane is taken as a Z direction. Although the direction from the base plate 10 to the first resin layer 71 and the second resin layer 72 in the Z direction is taken as upward, and the reverse direction is taken as downward, "upward" and "downward" are used in the description for convenience and do not always coincide with the direction of gravity.

[0011] The power module 100 further includes a metal member 50 disposed between the electrode plate 22 and the external terminal plate 61 and connecting the electrode plate 22 and the external terminal plate 61, a bonding member 80 connecting the metal member 50 and the electrode plate 22, and a wire 40 connecting the electrode plate 22 and the top electrode 30b of the semiconductor chip 30.

[0012] The external output terminal plate 61, the semiconductor chip 30 that outputs power to the terminal plate 61, the metal member 50 that connects the terminal plate 61 and the semiconductor chip 30, the electrode plate 22, and the wire 40 will now be described in detail. The external output terminal plate 61 is described in the description below, and this is the same for the other terminal plates 60.

[0013] The casing 11 is made of, for example, a heat-insulating resin material and is formed by combining, for example, the bottom side part 11a forming the lower surface, a side wall part 11b forming the side surface, and the top side part 11c forming the upper surface. The casing 11 is hollow inside.

[0014] The semiconductor chip 30 is arranged with another semiconductor chip 30 on the first surface 10A of the base plate 10. The semiconductor chip 30 is, for example, a rectangular parallelepiped whose length in the X-direction and Y-direction is greater than the length in the Z-direction. The semiconductor chip 30 has a bottom electrode 30a connected to an end portion 21a of the electrode plate 21 at the bottom of the semiconductor chip 30, and a top electrode 30b connected to a chip connection portion 40b of the wire 40 at the top of the semiconductor chip 30.

[0015] For example, the base plate 10 is made of insulating ceramic and is substantially plate-shaped and parallel to the XY plane. The electrode plates 21 and 22 are bonded to the first surface 10A of the base plate 10 and provided so as to be substantially parallel to the first surface 10A. For example, electrode plates 21 and 22 are formed by punching a copper sheet into the desired wiring configuration. The electrode plates 21 and 22 extend near the terminal plates 60 and the plurality of semiconductor chips 30, respectively, and are connected to the terminal plates 60 and the semiconductor chips 30 by soldering, ultrasonic bonding, silver sintering, etc. Specifically, the end portion 21a of the electrode plate 21 is disposed below the semiconductor chip 30 and is connected to the bottom electrode 30a of the semiconductor chip 30, for example, by soldering.

[0016] The electrode plate 22 connects the terminal plate 61 and the top electrode 30b of the semiconductor chip 30.

[0017] A first connecting part 22a, which is a part of the electrode plate 22, is arranged on the periphery of the semiconductor chip 30, and a second connecting part 22b, which is another part of the electrode plate 22, is arranged under the terminal plate 61. The first connecting part 22a is connected to an electrode plate connecting part 40a, which is the end part of the wire 40 connected to the top electrode 30b of the semiconductor chip 30.

[0018] The metal member 50 is disposed on the second connecting part 22b. The second connecting part 22b is connected to a bottom surface 50c of the metal member 50 by the bonding member 80, which is, for example, solder, etc.; therefore, as viewed from above, the outer edge of the electrode plate 22 is located outside the outer edge of the bottom surface 50c of the metal member 50, so that the bonding member 80 does not fall off the electrode plate 22. The electrode plate 22 is connected to the terminal plate 61 via the metal member 50 because the second connecting part 22b is connected to the metal member 50, which is connected to the terminal plate 61.

[0019] The metal member 50 comprises a metal, such as copper, and has, for example, a rectangular parallelepiped shape; the surfaces of the metal member 50 include an upper surface 50a, a lower surface 50c, and four side surfaces 50b. However, the configuration is not limited to this; it is sufficient that the metal member 50 has the upper surface 50a and the lower surface 50c. The upper surface 50a is, for example, rectangular and parallel to the lower surface of a bonding part 61a of the terminal plate 61. For example, the lower surface 50c is also rectangular and parallel to the second connecting part 22b of the electrode plate 22. The side surfaces 50b protrude upward from the four sides of the lower surface 50c in the Z direction and are attached to the four sides of the upper surface 50a.

[0020] The bottom surface 50c occupies a narrower area than the second connecting part 22b because the bottom surface 50c is connected to the second connecting part 22b of the electrode plate 22. The top surface 50a occupies a wider area than the bonding part 61a because the top surface 50a is attached to the bonding part 61a of the terminal plate 61.

[0021] For example, the bonding member 80 is made of solder or the like, is in contact with the metal member 50 and the second connecting part 22b, and fixes and connects the metal member 50 and the second connecting part 22b by self-hardening. Specifically, the bonding member 80 is in contact with the four side surfaces 50b of the metal member 50 and the second connecting part 22b at the edge of the side surfaces 50b and extends downward.

[0022] The terminal plate 61 includes the bonding part 61a in contact with the bottom surface 50a of the metal member 50, a curved part 61b curved upward from the bonding part 61a, a first intermediate part 61c extending upward in the Z direction from the curved part 61b, a second intermediate part 61d extending further along the XY plane from the first intermediate part 61c, a third intermediate part 61e extending further upward in the Z direction from the second intermediate part 61d, and a lead-out part 61f extending further along the XY plane by bending from the third intermediate part 61e and led out of the housing 11. The bonding part 61a, the curved part 61b, the first intermediate part 61c, the second intermediate part 61d, the third intermediate part 61e and the lead-out part 61f are designed to have a continuous body and are arranged in this order.The terminal plate 61 comprises copper and is manufactured, for example, by punching and bending a copper sheet. The terminal plate 61 is aligned inside the housing 11 by fixing the bonding part 61a by bonding the metal member 50 and fixing the lead-out part 61f by clamping between the top part 11c and the side wall part 11b of the housing 11.

[0023] The bonding portion 61a is parallel to the top surface 50a of the metal member 50 and extends along the top surface 50a. The bonding portion 61a is in contact with the top surface 50a and is joined to the top surface 50a, for example, by ultrasonic bonding. The bottom surface of the bonding portion 61a is smaller than the top surface 50a. The curved portion 61b is curved upward to join the bonding portion 61a parallel to the XY plane and the first intermediate portion 61c extending in the Z direction. The curved portion 61b separates from the top surface 50a of the metal member 50 as it curves upward; thereby, a wedge-shaped gap 90 is formed between the bottom surface of the curved portion 61b and the top surface 50a of the metal member 50. The second resin layer 72 enters the gap 90.The lead-out part 61f is led out from the curved part 61b via the first intermediate part 61c, the second intermediate part 61d and the third intermediate part 61e and has a part exposed outside the power module 100.

[0024] The wire 40 connects the electrode plate 22 and the top electrode 30b of the semiconductor chip 30. The wire 40 is, for example, wire-shaped and made of aluminum, etc. One end of the wire 40 is the chip connecting part 40b connected to the semiconductor chip 30 and is connected to the top electrode 30b of the semiconductor chip 30, for example, by ultrasonic bonding. The other end of the wire 40 is the electrode plate connecting part 40a connected to the electrode plate 22 and is connected to the first connecting part 22a of the electrode plate 22, for example, by ultrasonic bonding, etc. There are also cases where the electrode plate connecting part 40a and the chip connecting part 40b are constrained by bonding, hardened by alloying, and have bulged spherical shapes.

[0025] The length in the Z direction of the metal member 50 and the length in the Z direction of the terminal plate 61 are set such that a length L1 from the first surface 10A of the base plate 10 to the chip connecting part 40b of the wire 40 is smaller than a length L2 from the first surface 10A to the bonding part 61a of the terminal plate 61.

[0026] When a crowned shape is formed in the chip connecting part 40b, it is preferable to set the length from the first surface 10A to the top end of the crowned shape of the chip connecting part 40b of the wire 40 to be smaller than the length L2.

[0027] Regarding the hardening of the wire 40 due to the bonding of the chip connection part 40b, it is preferable to set the length from the first surface 10A to the top end of a connection effect part 40bb to be smaller than L2 for the connection effect part 40bb formed at the end part of the wire 40 on the chip connection part 40b side. The connection effect part 40bb is a part where bendability is reduced due to, for example, a change in the crystal structure of the wire 40 due to the heat effect when connecting the chip connection part 40b and the top electrode 30b of the semiconductor chip 30. The length of the connection effect part 40bb in the Z direction is taken as C. It is preferable that the value of C is, for example, 0.2 to 1 mm.

[0028] For an upper part 40c of the wire 40, which is the highest part of the wire 40, it is advantageous that the length from the first surface 19A to the upper part 40c is less than L2.

[0029] The first resin layer 71 and the second resin layer 72 fill the internal space surrounded by the base plate 10 and the housing 11 and ensure insulation between the plurality of terminal plates 61, 62 and 63, the semiconductor chip 30, the electrode plates 21 and 22, the wire 40, etc. The second resin layer 72 is arranged on the first resin layer 71.

[0030] The elastic modulus of the first resin layer 71 is greater than the elastic modulus of the second resin layer 72. The thermal expansion coefficient of the first resin layer 71 is smaller than the thermal expansion coefficient of the second resin layer 72. The first resin layer 71 comprises, for example, an epoxy resin. The second resin layer 72 comprises, for example, polymer silicone and is an insulating gel resin.

[0031] The first resin layer 71 is provided on the first surface 10A. A bottom surface of the first resin layer 71 is in contact with the first surface 10A and the electrode plates 21 and 22.

[0032] A position Z0 on the Z-axis of a top surface 71A of the first resin layer 71 is positioned higher than a position Zt on the Z-axis of the chip connecting part 40b of the wire 40 and lower than a position Zc on the Z-axis of the bottom surface of the bonding part 61a of the terminal board 61. With respect to the length from the first surface 10A, a length L of the top surface 71A of the first resin layer 71 is greater than the length L1 of the chip connecting part 40b of the wire 40 and smaller than the length L2 to the bonding part 61a of the terminal board 61. In such a case, the chip connecting part 40b of the wire 40, the semiconductor chip 30, and the electrode plates 21 and 22 lower than the position Zt on the Z-axis, and the parts of the metal member 50, the bonding member 80, and the wire 40 lower than the top surface 71A of the first resin layer 71 are arranged inside the first resin layer 71.

[0033] When the chip connecting part 40b has a spherical shape, it is more advantageous to use the upper end of the spherical shape of the chip connecting part 40b as the Z-axis position Zt. Regarding the length from the first surface 10A, it is more advantageous that the length L1 be the length to the upper end of the spherical shape of the chip connecting part 40b. In such a case, the spherical chip connecting part 40b of the wire 40, the semiconductor chip 30, and the electrode plates 21 and 22 that are lower than the Z-axis position Zt, and the parts of the metal member 50, the bonding member 80, and the wire 40 that are lower than the top surface 71A of the first resin layer 71 are arranged inside the first resin layer 71.

[0034] Regarding the hardening of the wire 40 due to the bonding of the chip connection part 40b, it is more advantageous to use the position on the Z-axis of the upper end of the connection effect part 40bb as Zt. Regarding the length from the first surface 10A, it is more advantageous that the length L1 be the length to the upper end of the connection effect part 40bb. In such a case, the connection effect part 40bb of the wire 40, the semiconductor chip 30, and the electrode plates 21 and 22 that are lower than the position Zt on the Z-axis, and the parts of the metal member 50, the bonding member 80, and the wire 40 that are lower than the upper surface 71A of the first resin layer 71 are arranged inside the first resin layer 71.

[0035] It is more advantageous to use the position of the upper part 40c on the Z-axis, which is the highest part of the wire 40, as Zt. Regarding the length from the first surface 10A, it is more advantageous to use the length to the upper part 40c as L1. In such a case, the wire 40, the semiconductor chip 30, and the electrode plates 21 and 22 that are lower than the position Zt on the Z-axis, and the parts of the metal member 50, the bonding member 80, and the wire 40 that are lower than the top surface 71A of the first resin layer 71 are arranged inside the first resin layer 71.

[0036] The terminal plate 61 is not disposed inside the first resin layer 71, regardless of which of the chip connection part 40b, the top end of the spherical shape, the top end of the connection effect part 40bb, or the top part 40c is used as a reference for Zt and L1. The electrode plates 21 and 22, the semiconductor chip 30, and the parts of the metal member 50, the bonding member 80, and the wire 40 that are lower than the top surface 71A of the first resin layer 71 are disposed inside the first resin layer 71 and insulated by the first resin layer 71.

[0037] The second resin layer 72 is provided on the first resin layer 71, and the entire surface of a bottom surface 72B of the second resin layer 72 is closely adhered to the entire surface of the top surface 71A of the first resin layer 71. Accordingly, the Z-axis position Z0 of the bottom surface 72B of the second resin layer 72 is positioned higher than the Z-axis position Zt of the chip connection part 40b of the wire 40 and lower than the Z-axis position Zc of the bottom surface of the bonding part 61a of the terminal board 61. Thereby, the chip connection part 40b of the wire 40 is not disposed inside the second resin layer 72.

[0038] When forming the spherical shape in the chip connecting part 40b, it is more preferable that the position on the Z-axis of the top end of the spherical shape be used as Zt. Regarding the length from the first surface 10A, it is more preferable that the length L1 be the length to the top end of the spherical shape. This prevents the spherical shape of the chip connecting part 40b of the wire 40 from being located inside the second resin layer 72.

[0039] Regarding the connection effect part 40bb, it is more preferable to use the position on the Z-axis of the upper end of the connection effect part 40bb as Zt. Regarding the length from the first surface 10A, it is more preferable that the length L1 be the length to the upper end of the connection effect part 40bb. This prevents the connection effect part 40bb of the wire 40 from being disposed inside the second resin layer 72.

[0040] It is more advantageous to use the position on the Z-axis of the upper part 40c of the wire 40 as Zt. Regarding the length from the first surface 10A, it is more advantageous that the length L1 be the length to the upper part 40c. In such a case, not all of the wire 40 is disposed inside the second resin layer 72.

[0041] Regardless of which of the chip connection part 40b, the top end of the spherical shape, the top end of the connection effect part 40bb, or the top part 40c is used as the reference for Zt and L1, the electrode plate connection part 40a and the chip connection part 40b of the wire 40 are not arranged inside the second resin layer 72. Furthermore, the terminal plate 61, except for the part of the lead-out part 61f exposed to the outside and the part of the metal member 50 having at least the top surface 50a higher than the bottom surface 72B of the second resin layer 72, are arranged inside the second resin layer 72.

[0042] The following describes the functionality based on the line of the power module 100. Fig. 2A schematically shows the deformation when thermal expansion of the first resin layer 71 and the second resin layer 72 occurs due to heat generation due to conduction. The position on the Z-axis of a top surface 72A of the second resin layer 72 before heat generation is taken as Za, and the position on the Z-axis of the top surface 72A of the second resin layer 72 after heat generation due to conduction is taken as Zb. Compared with the second resin layer 72, the thermal expansion of the first resin layer 71 is small because the first resin layer 71 has a lower thermal expansion coefficient than the second resin layer 72; therefore, for the sake of simplicity of description, the position of the top surface 71A of the first resin layer 71 is taken as Z0 and does not change before and after conduction.

[0043] When heat generation occurs due to conduction, the position of the upper surface 71A of the first resin layer 71 remains at Z0; therefore, the lower surface 72B of the second resin layer 72, which is in contact with the upper surface 71A of the first resin layer 71, is substantially not displaced and remains at Z0. The upper surface 72A of the second resin layer 72 expands upward, the stress inside the second resin layer 72 is applied upward, and the terminal plates 60 and the wire 40 arranged inside the second resin layer 72 are stressed upward.

[0044] Even when an upward load is applied to the second resin layer 72, the second resin layer 72, which has a low elastic modulus and low thermal stress, does not easily separate from the surface of the terminal plate 61. Therefore, the second resin layer 72 does not easily separate at the wedge gap 90 between the bottom surface of the curved part 61b and the top surface 50a of the metal member 50 and remains tightly adhered. Therefore, the second resin layer 72 continues to maintain the insulating properties for the terminal plate 61 even during heat generation due to conduction.

[0045] Furthermore, the parts of the wire 40 other than the electrode plate connecting part 40a and the chip connecting part 40b have excellent bendability, etc., and are therefore not easily damaged by breakage, etc. due to the upward stress of the second resin layer 72 undergoing thermal expansion, even when they are disposed inside the second resin layer 72. Furthermore, the second resin layer 72 maintains the insulation properties for the wire 40 disposed inside the second resin layer 72 without separating from the wire 40.

[0046] The electrode plate connecting part 40a and the chip connecting part 40b of the wire 40, which have low bendability because they are bonded by ultrasonic bonding, are fixed and arranged within the first resin layer 71, which has a high elastic modulus and a low thermal expansion coefficient. Therefore, the electrode plate connecting part 40a and the chip connecting part 40b are not easily subjected to upward stress and are difficult to break.

[0047] When the spherical shape is formed in the chip connection part 40b by bonding, by using the upper end of the spherical shape as Zt, the part up to the upper end of the spherical shape is fixed and arranged inside the resin layer 71, and the effects of the upward stress due to heat generation can be further reduced. Regarding the connection effect part 40bb hardened by bonding, by using the upper end of the connection effect part 40bb as Zt, the part up to the connection effect part 40bb is also fixed and arranged inside the first resin layer 71, and the effects of the upward stress can be further reduced. When the upper part 40c of the wire 40 is used as Zt, the entire wire 40 is fixed and arranged inside the first resin layer 71, and the effects of the upward stress can be further reduced.

[0048] The following describes the effects of the embodiment. In the embodiment, the electrode plate connecting part 40a and the chip connecting part 40b of the wire 40, which have reduced bendability due to bonding, are fixed and arranged inside the first resin layer 71, which has a low elastic modulus and a low thermal expansion coefficient; therefore, fatigue fracture does not easily occur even when external electrical energy flows in and generates heat. Also, even if the chip connecting part 40b is formed into a spherical shape due to bonding, the entire chip connecting part 40b can be protected with the spherical shape if the part up to the top of the spherical shape is fixed and arranged inside the first resin layer 71.Furthermore, if the parts up to the top of the connection effect part 40bb, which have been hardened by bonding the chip connection part 40b, are fixed and arranged inside the first resin layer 71, the connection effect part 40bb can also be protected by the first resin layer 71. Furthermore, if the entire wire 40 is fixed and arranged inside the first resin layer 71, the entire wire 40 can be protected by the first resin layer 71.

[0049] In the embodiment, the gel-like second resin layer 72 enters the wedge-shaped gap 90. Therefore, even if the curved part 61b of the terminal plate 61 has a micro-displacement due to the upward load due to the expansion of the second resin layer 72 due to heat generation during conduction, the gel-like second resin layer 72 disposed in the gap 90 can deform with the micro-displacement of the curved part 61b; therefore, the second resin layer 72 does not easily separate from the bottom of the curved part 61b. Therefore, the reliability of the power module 100 according to the embodiment is high.

[0050] The bonding member 80 spreads and adheres to cover the side surfaces 50b of the metal member 50 and the surface of the second connecting part 22b of the electrode plate 22, which have a substantially orthogonal relationship; therefore, an angle α between the second connecting part 22b of the electrode plate 22 and the surface of the bonding member 80 and an angle β between the surface of the side surface 50b and the surface of the bonding member 80 can be obtuse; therefore, the separation of the first resin layer 71 from the electrode plate 22, the metal member 50, and the bonding member 80 can be suppressed even when the upward stress of the second resin layer 72 is transmitted via the terminal plate 61.

[0051] Therefore, in the power module 100 according to the embodiment, even when the amount of heat generation increases with the increase in the conduction amount and the thermal expansion of the second resin layer 72 occurs, vibration fracture of the wire 40 can be suppressed. Furthermore, even when the terminal plate 61 is stressed by the expansion of the second resin layer 72, separation of the second resin layer 72 from the bottom surface of the curved part 61b can be suppressed, and the insulation properties can be ensured. Accordingly, the reliability of the power module 100 can be increased.

[0052] Although the external output terminal plate 61 is described in the embodiment, the embodiments are not limited to this. For example, when used for the input terminal plates 62 and 63 and the internal wiring terminal plates, which are other terminal plates of the power module 100, and for the semiconductor chips 30 connected to the terminal plates, similar effects can be provided.

[0053] Although the semiconductor chip 30 and the external output terminal plate 61 connected to the semiconductor chip 30 are described in the embodiment, the embodiment is not limited thereto. The same effects are also provided for the relationship between another semiconductor chip 30 and the terminal plate 60 not directly connected to the semiconductor chip 30.

[0054] The operation of a power module 200 of a comparative example 1 and a power module 300 of a comparative example 2 in which the structure of the embodiment is not used will now be described. Fig. 3A is a partial cross-sectional view showing the power module according to Comparative Example 1. Only the gel-like second resin layer 72 is filled as the resin layer in the power module 200.

[0055] As in Fig. As shown in Figure 3A, the top surface 10A of the base plate 10 is taken as the Z-axis 0. The position of the top surface 72A of the second resin layer 72 in front of the conduction is Za1. When heat is generated inside the power module 200 through the conduction, thermal expansion of the second resin layer 72 occurs, and the top surface 72A of the second resin layer 72 is displaced toward Zb1. As the second resin layer 72 expands, an upward thermal stress is generated inside the second resin layer 72; therefore, for example, an upward stress is applied to the wire 40, etc. When the conduction ends and the heat decreases, the second resin layer 72 contracts to the original volume, and the top surface of the second resin layer 72 returns to Za1. Because the thermal stress disappears when the second resin layer 72 contracts, the upward stress on the wire 40 disappears, etc.Repeating this movement may cause vibration fracture of the electrode plate connecting part 40a and / or the chip connecting part 40b of the wire 40.

[0056] Fig. 3B is a partial cross-sectional view showing the power module according to Comparative Example 2. The power module 300 has the structure of Comparative Example 1, in which the first resin layer 71 is also used. In order to prevent fatigue fracture of the electrode plate connecting part 40a and the chip connecting part 40b of the wire 40, with respect to Fig.To prevent the thermal expansion described in FIG. 3A, the first resin layer 71, which has a high elastic modulus and a low thermal expansion coefficient, is disposed under the second resin layer 72, and the electrode plate connecting part 40a and the chip connecting part 40b of the wire 40 are disposed inside the first resin layer 71. When the second resin layer 72 undergoes thermal expansion due to heat generation due to conduction, the upper surface 72A of the second resin layer 72 is displaced from Za2 to Zb2. Compared with the second resin layer 72, the thermal expansion of the first resin layer 71 is small; therefore, the position of the upper surface of the first resin layer 71 is noted as Z02 for convenience in the present form.

[0057] The fatigue cracking due to thermal expansion of the second resin layer 72 can be suppressed because the electrode plate connecting part 40a and the chip connecting part 40b of the wire 40 are disposed inside the first resin layer 71. The first intermediate part 61c, the second intermediate part 61d, and the third intermediate part 61e of the terminal plate 61, which are disposed inside the second resin layer 72, are subjected to upward stress from the second resin layer 72; therefore, the entire output terminal plate 61 is subjected to upward stress.In such a case, there is a risk that the first resin layer 71, which enters a wedge gap 99 between the underside of the curved part 61b and the second connecting part 22b of the electrode plate 22, may not deform with the micro-displacement of the curved part 61b subjected to the upward load due to the high elastic modulus of the first resin layer 71, and the first resin layer 71 may separate from the curved part 61b. If both the terminal plate 61 and the electrode plate 22 are made of copper for bonding using ultrasonic bonding, the first resin layer 71, made of, for example, an epoxy resin, undesirably separates even more easily from the underside of the curved part 61b.

[0058] Conversely, according to the above-described embodiment, the electrode plate connecting part 40a of the wire 40 can be protected by the first resin layer 71 having the high elastic modulus, and the gel-like second resin layer 72 enters the wedge gap 90 and therefore does not easily separate from the curved part 61b of the terminal plate 61. Therefore, the reliability of the power module 100 according to the embodiment is high compared with Comparative Example 1 and Comparative Example 2.

[0059] According to the embodiments described above, a power module with high reliability can be realized.

[0060] In the foregoing, an embodiment of the invention is described with reference to specific examples. However, the embodiment of the invention as defined in the claims is not limited to these specific examples. For example, a person skilled in the art can similarly implement the invention by appropriately selecting specific configurations of the shapes, materials, and arrangements of the electrode plate, the metal element, the terminal plate, and the semiconductor chip included in the power module from the known art, and such an implementation is within the scope of the invention to the extent that similar effects can be achieved. In particular, the materials of the electrode plate, the terminal plate, and the wire are not limited to copper or aluminum, and may be another metal or metals different from each other.Combinations of two or more components of the specific examples to the extent of technical feasibility are also within the scope of the invention to the extent that the spirit of this invention is included.

Claims

[1] Power module (100), comprising: a base plate (10) having a first surface; a plurality of electrode plates (21, 22) provided on the first surface; a semiconductor chip (30) provided on the first surface; a wire (40) connected to the semiconductor chip (30) and one of the electrode plates (21, 22); a metal element (50) connected to one of the electrode plates (21, 22); a terminal plate (61) having a bonding part (61a), a curved part (61b), a first intermediate part (61c), a second intermediate part (61d), a third intermediate part (61e), and a lead-out part (61e), wherein the bonding part (61a) is in contact with an upper surface of the metal element (50) and extends along the upper surface, the curved part (61b) is curved upwards from the bonding part (61a), the first intermediate part (61c) extends upwards from the curved part (61b), the second intermediate part (61d) extends from the first intermediate part (61c) in a direction parallel to the first surface, the third intermediate part (61e) extends upwards from the second intermediate part (61d), and the lead-out part (61e) is led outwards from the third intermediate part (61e); a first resin layer (71), wherein a connecting part (40b) of the wire (40) and the semiconductor chip (30) are arranged inside the first resin layer (71); and a second resin layer (72) provided on the first resin layer (71), wherein the curved part (61b) is arranged inside the second resin layer (72), wherein an elastic modulus of the second resin layer (72) is lower than an elastic modulus of the first resin layer (71), wherein a length between the first surface and a bottom of the bonding part (61a) is greater than a length between the first surface and the connecting part (40b), wherein a thermal expansion coefficient of the first resin layer (71) is smaller than a thermal expansion coefficient of the second resin layer (72), the connecting plate (61) is formed by bending a plate, and where a wedge-shaped gap is formed between the underside of the curved part (61b) of the connecting plate (61) and the upper side of the metal element (50), and the second resin layer (72) enters the gap. [2] The module (100) according to claim 1, wherein an upper surface of the first resin layer (71) is positioned higher than the connecting part (40b) and lower than the bonding part (61a). [3] Module (100) according to claim 1 or 2, wherein a connection effect part (40bb) has a reduced bendability and is formed at an end part of the wire (40) on the side of the connection part (40b) by connecting the connection part (40b) and the semiconductor chip (30), and the length between the first surface and the bottom of the bonding part (61a) is greater than a length between the first surface and an upper end of the connection effect part (40bb). [4] The module (100) according to claim 3, wherein the upper surface of the first resin layer (71) is positioned higher than the upper end of the connection effect part (40bb). [5] The module (100) according to any one of claims 1 to 4, further comprising a bonding element (80) in contact with the metal element (50) and the one of the electrode plates (21, 22). [6] Module (100) according to one of claims 1 to 5, wherein the first resin layer (71) comprises an epoxy resin. [7] Module (100) according to one of claims 1 to 6, wherein the second resin layer (72) is a gel.

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