Power module, method for manufacturing same, and power conversion device

Abstract

This power module (1) comprises a circuit board (12), a semiconductor element (30), a terminal (40), and a conductive connection member (52). The circuit board (12) includes an insulating layer (13) having a main surface (13b), and a conductive circuit pattern (15) provided on the main surface (13b). The semiconductor element (30) is joined to the conductive circuit pattern (15). The conductive circuit pattern (15) includes a conductive pattern (20). The terminal (40) includes a first end part (41). The first end part (41) of the terminal (40) includes a first surface (42) joined to the conductive pattern (20), and a second surface (43) on the opposite side of the first surface (42). The conductive connection member (52) is bridged between the second surface (43) of the terminal (40) and the conductive pattern (20).

Description

Power module, its manufacturing method, and power conversion device

[0001] The present disclosure relates to a power module, a manufacturing method thereof, and a power conversion device.

[0002] Japanese Patent Laid-Open Publication No. 2001-237359 (Patent Document 1) discloses a power semiconductor device including a semiconductor chip, a terminal fitting, and a resin case frame to which the terminal fitting is fixed. The terminal fitting includes a first electrode and a second electrode disposed at the tip of the terminal fitting relative to the first electrode. In this power semiconductor device, the electrical connection between the semiconductor chip and the terminal fitting can be selected between soldering between the second electrode and the semiconductor chip and bonding wire between the first electrode and the semiconductor chip.

[0003] Japanese Patent Application Laid-Open No. 2001-237359

[0004] An object of the present disclosure is to provide a power module and a power conversion device with improved reliability.

[0005] The power module of the present disclosure includes a circuit board, a semiconductor element, a terminal, and a first conductive connecting member. The circuit board includes an insulating layer having a main surface and a conductive circuit pattern provided on the main surface. The semiconductor element is bonded to the conductive circuit pattern. The conductive circuit pattern includes a first conductive pattern. The terminal includes a first end. The first end of the terminal includes a first surface bonded to the first conductive pattern and a second surface opposite the first surface. The first conductive connecting member bridges between the second surface and the first conductive pattern.

[0006] A method for manufacturing a power module according to the present disclosure includes preparing a circuit board. The circuit board includes an insulating layer having a main surface and a conductive circuit pattern provided on the main surface. The conductive circuit pattern includes a first conductive pattern. A method for manufacturing a power module according to the present embodiment includes joining a semiconductor element to the conductive circuit pattern and joining a terminal to the first conductive pattern. The terminal includes a first end. The first end of the terminal includes a first surface joined to the first conductive pattern and a second surface opposite the first surface. A method for manufacturing a power module according to the present embodiment includes bridging a first conductive connecting member between the second surface and the first conductive pattern.

[0007] The power conversion device of the present disclosure includes a main conversion circuit that has the power module of the present disclosure and converts and outputs input power, and a control circuit that outputs a control signal to the main conversion circuit to control the main conversion circuit.

[0008] The terminal is electrically connected to the first conductive pattern not only by the joint between the first surface of the terminal and the first conductive pattern but also by the first conductive connection member. Therefore, even if the joint is peeled off from the first conductive pattern, the terminal remains electrically connected to the first conductive pattern through the first conductive connection member. The power module and power conversion device of the present disclosure have improved reliability.

[0009] FIG. 1 is a schematic cross-sectional view of a power module of embodiment 1. FIG. 2 is a schematic partially enlarged perspective view of the power module of embodiment 1. FIG. 3 is a schematic partially enlarged plan view of the power module of embodiment 1. FIG. 4 is a diagram showing a flowchart of a method for manufacturing the power module of embodiment 1. FIG. 5 is a schematic partially enlarged perspective view of a power module of a modified example of embodiment 1. FIG. 6 is a schematic partially enlarged plan view of a power module of a modified example of embodiment 1. FIG. 7 is a schematic partially enlarged plan view of a power module of embodiment 2. FIG. 8 is a schematic partially enlarged plan view of a power module of a first modified example of embodiment 2. FIG. 9 is a schematic partially enlarged plan view of a power module of a second modified example of embodiment 2. FIG. 10 is a schematic partially enlarged plan view of a power module of embodiment 3. FIG. 11 is a schematic partially enlarged perspective view of the power module of embodiment 3. FIG. 12 is a block diagram showing the configuration of a power conversion system of embodiment 4.

[0010] Hereinafter, embodiments of the present disclosure will be described. Note that the same reference numerals are used to designate the same components, and the description thereof will not be repeated.

[0011] 1 to 3, a power module 1 according to a first embodiment will be described. The power module 1 includes a circuit board 12, semiconductor elements 30 and 31, terminals 40, and conductive connecting members 50, 51, and 52. The power module 1 may further include a base plate 10, a case 60, and a sealing member 61.

[0012] The base plate 10 supports the circuit board 12. The base plate 10 dissipates heat generated in the power module 1 to the outside of the power module 1. The base plate 10 is formed of, for example, copper (Cu) or a silicon carbide particle reinforced aluminum composite (AlSiC). The base plate 10 may be provided with cooling fins (not shown).

[0013] The circuit board 12 includes an insulating layer 13 and a conductive circuit pattern 15. The circuit board 12 may further include a conductor pattern 14.

[0014] The insulating layer 13 is made of, for example, alumina (Al ２ O ３ The insulating layer 13 is made of an insulating material such as aluminum nitride (AlN), resin, or filler-containing resin. The insulating layer 13 has a main surface 13a and a main surface 13b opposite to the main surface 13a.

[0015] The conductor pattern 14 is provided on the main surface 13a. The conductive circuit pattern 15 is provided on the main surface 13b. The conductive circuit pattern 15 includes a conductive pattern 20. The conductive pattern 20 is, for example, a conductive bonding pad to which the terminal 40 is bonded. The conductive pattern 20 may be spaced apart from the portion of the conductive circuit pattern 15 to which the semiconductor elements 30 and 31 are bonded. The conductor pattern 14 and the conductive circuit pattern 15 are formed of a conductive material such as copper (Cu) or aluminum (Al). The conductor pattern 14 and the conductive circuit pattern 15 may have a two-layer structure including an aluminum (Al) layer in contact with the insulating layer 13 and a copper (Cu) layer provided on the aluminum (Al) layer. The surface of the conductive circuit pattern 15 may be provided with an uneven structure or coating to improve adhesion between the conductive circuit pattern 15 and the sealing member 61.

[0016] The circuit board 12 is fixed to the base plate 10 at a joint 11. Specifically, the conductor pattern 14 is joined to the base plate 10 at the joint 11. The joint 11 may be formed of, for example, solder, a metal microparticle sintered body such as a silver microparticle sintered body, or a resin containing a conductive filler, or may be liquid phase diffusion bonding between the conductor pattern 14 and the base plate 10.

[0017] The semiconductor elements 30 and 31 are, for example, power semiconductor elements. Specifically, the semiconductor elements 30 and 31 are switching elements such as insulated gate bipolar transistors (IGBTs) or metal oxide semiconductor field effect transistors (MOSFETs), or rectifying elements such as Schottky barrier diodes. The semiconductor elements 30 and 31 are formed of silicon (Si) or a wide-bandgap semiconductor material having a bandgap larger than that of silicon (Si). Examples of wide-bandgap semiconductor materials include silicon carbide (SiC), gallium nitride (GaN)-based materials, and diamond. By forming the semiconductor elements 30 and 31 from a wide-bandgap semiconductor material, the allowable current density of the semiconductor elements 30 and 31 is improved and the power loss in the semiconductor elements 30 and 31 is reduced. As a result, the power module 1 can be miniaturized.

[0018] The semiconductor elements 30 and 31 have electrodes. The electrodes of the semiconductor elements 30 and 31 are formed of, for example, aluminum (Al) or an aluminum alloy with added silicon (Si). A coating layer such as a nickel (Ni) layer or a gold (Au) layer may be provided on the electrodes of the semiconductor elements 30 and 31.

[0019] The semiconductor element 30 is bonded to the conductive circuit pattern 15 at a bonding portion 33. The semiconductor element 31 is bonded to the conductive circuit pattern 15 at a bonding portion 34. The bonding portions 33 and 34 may be formed of, for example, solder, a metal microparticle sintered body such as a silver microparticle sintered body, or a resin containing a conductive filler, or may be liquid phase diffusion bonding between the electrodes of the semiconductor elements 30 and 31 and the conductive circuit pattern 15.

[0020] The terminals 40 extend to the outside of the case 60. Current from the power module 1 is extracted to the outside of the power module 1 through the terminals 40. The terminals 40 are formed of a conductive material such as copper (Cu) or aluminum (Al). A coating layer (not shown) such as a nickel (Ni) layer or a gold (Au) layer may be provided on the surface of the terminals 40.

[0021] The terminal 40 includes a first end 41. The first end 41 is an end of the terminal 40 that is closer to the circuit board 12. The first end 41 includes a first surface 42 and a second surface 43 opposite the first surface 42. The first surface 42 of the terminal 40 is joined to the conductive pattern 20 at a joint 45. The joint 45 may be formed, for example, from solder, a metal microparticle sintered body such as a silver microparticle sintered body, or a resin containing a conductive filler, or may be liquid phase diffusion bonding between the first surface 42 of the terminal 40 and the conductive pattern 20.

[0022] 1, in this embodiment, the terminal 40 is an outsert-type terminal that can be easily separated from the case 60. The terminal 40 may also be an insert-type terminal that is integrated with the case 60.

[0023] The conductive connection members 50, 51, and 52 are formed of a conductive material such as aluminum (Al) or copper (Cu). The conductive connection member 50 bridges the semiconductor element 30 and the conductive pattern 20. The conductive connection member 50 is, for example, a conductive wire bonded to an electrode of the semiconductor element 30 and the conductive pattern 20. The conductive connection member 50 may be a conductive plate bonded to the electrode of the semiconductor element 30 and the conductive pattern 20 using a bonding material such as solder. The conductive connection member 51 bridges the semiconductor elements 30 and 31. The conductive connection member 51 is, for example, a conductive wire bonded to an electrode of the semiconductor element 30 and an electrode of the semiconductor element 31.

[0024] The conductive connection member 52 bridges between the conductive pattern 20 and the second surface 43 of the first end 41 of the terminal 40. The conductive connection member 52 is, for example, a conductive wire bonded to the conductive pattern 20 and the second surface 43 of the first end 41 of the terminal 40.

[0025] The case 60 protects the circuit board 12 and the semiconductor elements 30 and 31. The case 60 is fixed to the base plate 10 using an adhesive (not shown). The case 60 is made of an insulating resin such as an epoxy resin or a polyphenylene sulfide resin.

[0026] The sealing member 61 seals the semiconductor elements 30, 31. The sealing member 61 is formed of, for example, a thermosetting resin such as epoxy resin, silicone gel, or an insulating resin containing a metal or filler. The semiconductor elements 30, 31, which are made of a wide bandgap semiconductor material, can reach high temperatures of approximately 200°C during operation. By using an insulating resin containing a metal or filler as the material for the sealing member 61, the sealing member 61 is prevented from softening or deteriorating even at such high temperatures. This can prevent a decrease in the reliability of the joints of the conductive connecting members 50, 51, 52.

[0027] The sealing member 61 may have a multi-layer structure including a first sealing layer (not shown) that covers the joints between the semiconductor elements 30, 31 and the conductive connecting members 50, 51, and a second sealing layer (not shown) that is provided on the first sealing layer, the circuit board 12, the semiconductor elements 30, 31, and the base plate 10. The first sealing layer is formed of a material harder than the second sealing layer, and reinforces the joints between the semiconductor elements 30, 31 and the conductive connecting members 50, 51. For example, the first sealing layer is formed of an epoxy resin, and the second sealing layer is formed of a gel or the like.

[0028] An example of a method for manufacturing the power module 1 of this embodiment will be described with reference to Fig. 4. The method for manufacturing the power module 1 of this embodiment includes preparing a circuit board 12 (S1). The circuit board 12 includes an insulating layer 13 and a conductive circuit pattern 15. The insulating layer 13 has a main surface 13b. The conductive circuit pattern 15 is provided on the main surface 13b. The conductive circuit pattern 15 includes a conductive pattern 20. The circuit board 12 may further include a conductor pattern 14.

[0029] The method for manufacturing the power module 1 of this embodiment includes joining (S2) the semiconductor elements 30, 31 to the circuit board 12. The semiconductor elements 30, 31 are joined to the conductive circuit pattern 15 at joints 33, .

[0030] The method for manufacturing the power module 1 of this embodiment includes fixing the circuit board 12 to the base plate 10 (S3). The conductor patterns 14 of the circuit board 12 are joined to the base plate 10 at the joints 11.

[0031] The manufacturing method of the power module 1 of the present embodiment includes joining the terminal 40 to the conductive pattern 20 (S4). The terminal 40 includes a first end 41. The first end 41 of the terminal 40 includes a first surface 42 and a second surface 43 opposite to the first surface 42. The first surface 42 is joined to the conductive pattern 20. A joint 45 between the terminal 40 and the conductive pattern 20 may be formed, for example, from solder, a metal microparticle sintered body such as a silver microparticle sintered body, or a resin containing a conductive filler, or may be liquid phase diffusion bonding between the first surface 42 of the terminal 40 and the conductive pattern 20.

[0032] The manufacturing method of the power module 1 of this embodiment includes attaching (S5) the case 60 to the base plate 10. The case 60 is fixed to the base plate 10 using an adhesive (not shown).

[0033] The manufacturing method of the power module 1 of this embodiment includes providing conductive connection members 50, 51 (S6). The conductive connection member 50 bridges the conductive pattern 20 and the semiconductor element 30. The conductive connection member 50 is connected to the conductive pattern 20 and the semiconductor element 30. If the conductive connection member 50 is a conductive wire, the conductive wire is bonded to the conductive pattern 20 and the semiconductor element 30. The conductive connection member 50 bridges the semiconductor element 30 and the semiconductor element 31. The conductive connection member 51 is connected to the semiconductor element 30 and the semiconductor element 31. If the conductive connection member 51 is a conductive wire, the conductive wire is bonded to the semiconductor element 30 and the semiconductor element 31.

[0034] The manufacturing method of the power module 1 of the present embodiment includes bridging the conductive connection member 52 between the second surface 43 of the terminal 40 and the conductive pattern 20 (S7). The conductive connection member 52 is connected to the second surface 43 of the terminal 40 and the conductive pattern 20. If the conductive connection member 52 is a conductive wire, the conductive wire is bonded to the second surface 43 of the terminal 40 and the conductive pattern 20.

[0035] The manufacturing method of the power module 1 of the present embodiment includes providing (S8) the sealing member 61. For example, the sealing member 61 is provided by applying a sealing material to the space surrounded by the case 60 and the base plate 10.

[0036] As already mentioned, the sealing member 61 may have a multi-layer structure including a first sealing layer (not shown) and a second sealing layer (not shown). For example, the sealing member 61 having a multi-layer structure may be formed by applying a first sealing material to the connection portions between the semiconductor elements 30, 31 and the conductive connecting members 50, 51, and then applying a second sealing material onto the first sealing material, the circuit board 12, the semiconductor elements 30, 31, and the base plate 10.

[0037] A modified example of the manufacturing method of the power module 1 of this embodiment will be described. Steps S2 and S3 may be performed simultaneously. Step S3 may be performed before step S2. When the conductive connection members 50, 51, and 52 are the same conductive connection member, steps S6 and S7 may be performed simultaneously.

[0038] The operation of the power module 1 of this embodiment will be described. During operation of the power module 1, heat is generated from the semiconductor elements 30 and 31, and the semiconductor elements 30 and 31, terminals 40, and joints 45 become hot. In contrast, during operation of the power module 1, no heat is generated from the semiconductor elements 30 and 31, and the semiconductor elements 30 and 31, terminals 40, and joints 45 become cold. Due to such temperature cycles, thermal stress is repeatedly applied to the joints 45. Cracks occur at the ends of the joints 45, and these cracks propagate into the joints 45. This can cause the joints 45 to peel off from the conductive pattern 20.

[0039] However, in the power module 1, the terminals 40 are electrically connected to the conductive pattern 20 not only by the joints 45 but also by the conductive connection members 52. The conductive connection members 52 are bridged between the second surfaces 43 of the terminals 40 and the conductive pattern 20 and are deformable. Because the conductive connection members 52 deform in response to temperature cycles, thermal stress acting on the joints between the conductive connection members 52 and the terminals 40 and the joints between the conductive connection members 52 and the conductive pattern 20 is reduced. The joints between the conductive connection members 52 and the terminals 40 and the joints between the conductive connection members 52 and the conductive pattern 20 have higher durability against temperature cycles than the joints 45. Therefore, even if the joints 45 are peeled off from the conductive pattern 20, the terminals 40 remain electrically connected to the conductive pattern 20 through the conductive connection members 52. This can prevent the power module 1 from failing.

[0040] Furthermore, a portion of the current flowing through the power module 1 flows through the conductive connection member 52, reducing the current flowing through the joint 45. This suppresses a temperature rise in the joint 45 during operation of the power module 1, making the joint 45 less likely to peel off from the conductive pattern 20. This can suppress breakdowns in the power module 1.

[0041] When the terminals 40, the conductive patterns 20, and the conductive connection members 52 are made of the same material, the thermal stress acting on the joints between the conductive connection members 52 and the terminals 40 and the joints between the conductive connection members 52 and the conductive patterns 20 is further reduced. Therefore, even if the joints 45 are peeled off from the conductive patterns 20, the terminals 40 remain electrically connected to the conductive patterns 20 through the conductive connection members 52. This can prevent the power module 1 from failing.

[0042] When the terminals 40, the conductive patterns 20, and the conductive connecting members 52 are made of copper (Cu), the terminals 40, the conductive patterns 20, and the conductive connecting members 52 have the same hardness. Therefore, even when the conductive connecting members 52 are joined to the terminals 40 and the conductive patterns 20 by ultrasonic bonding, the terminals 40 and the conductive patterns 20 are not gouged out by the conductive connecting members 52, and the conductive connecting members 52 are well joined to the terminals 40 and the conductive patterns 20. This improves the reliability of the joints between the conductive connecting members 52 and the terminals 40 and the joints between the conductive connecting members 52 and the conductive patterns 20. This improves the reliability of the power module 1.

[0043] The bonding area of ​​the joint 45 is larger than the bonding area between the terminal 40 and the conductive connection member 52 and the bonding area between the conductive connection member 52 and the conductive pattern 20. When there is no crack in the joint 45, the electrical resistance between the terminal 40 and the conductive pattern 20 via the joint 45 is smaller than the electrical resistance between the terminal 40 and the conductive pattern 20 via the conductive connection member 52. Therefore, when a crack propagates in the joint 45, the electrical resistance between the terminal 40 and the conductive pattern 20 increases. Furthermore, when the joint 45 peels off from the conductive pattern 20, the electrical resistance between the terminal 40 and the conductive pattern 20 increases rapidly. For example, deterioration of the joint 45 can be detected by monitoring the electrical resistance between the conductive pattern 20 and the portion of the terminal 40 that extends outside the case 60.

[0044] A power module 1 according to a modification of the present embodiment will now be described. As shown in Figures 5 and 6, the conductive connection member 52 may be a conductive ribbon. Alternatively, the base plate 10 and the joints 11 may be omitted, and the conductor pattern 14 may function as the base plate 10.

[0045] The effects of the power module 1 of this embodiment will be described. The power module 1 of this embodiment includes a circuit board 12, a semiconductor element 30, a terminal 40, and a first conductive connecting member (conductive connecting member 52). The circuit board 12 includes an insulating layer 13 having a main surface 13b and a conductive circuit pattern 15 provided on the main surface 13b. The semiconductor element 30 is bonded to the conductive circuit pattern 15. The conductive circuit pattern 15 includes a first conductive pattern (conductive pattern 20). The terminal 40 includes a first end 41. The first end 41 of the terminal 40 includes a first surface 42 bonded to the first conductive pattern and a second surface 43 opposite the first surface 42. The first conductive connecting member bridges between the second surface 43 of the terminal 40 and the first conductive pattern.

[0046] In the power module 1, the terminal 40 is electrically connected to the first conductive pattern (the conductive pattern 20) not only by the joint 45 between the first surface 42 of the terminal 40 and the first conductive pattern, but also by the first conductive connecting member (the conductive connecting member 52). Therefore, even if the joint 45 is peeled off from the first conductive pattern, the terminal 40 remains electrically connected to the first conductive pattern through the first conductive connecting member. This improves the reliability of the power module 1.

[0047] The terminals 40 are bonded to the first conductive pattern (the conductive pattern 20) rather than to the semiconductor elements 30. Therefore, even if the number of semiconductor elements 30 is increased to increase the capacity of the power module 1, it is possible to suppress an increase in the manufacturing effort related to bonding the terminals 40. This improves the manufacturing efficiency of the power module 1.

[0048] The first conductive connection member (conductive connection member 52) is joined to the terminal 40 on a second surface 43 of the terminal 40 opposite to the first surface 42 of the terminal 40 joined to the first conductive pattern (conductive pattern 20). Therefore, the terminal 40 can be made smaller, and the power module 1 can be made smaller.

[0049] In the power module 1 of this embodiment, the first conductive connection member (conductive connection member 52) is a conductive wire or a conductive ribbon.

[0050] Therefore, even if the joint 45 between the first surface 42 of the terminal 40 and the first conductive pattern (the conductive pattern 20) is peeled off from the first conductive pattern (the conductive pattern 20), the terminal 40 remains electrically connected to the first conductive pattern through the first conductive connecting member (the conductive connecting member 52), thereby improving the reliability of the power module 1.

[0051] In the power module 1 of this embodiment, the first conductive pattern (conductive pattern 20), the terminal 40, and the first conductive connecting member (conductive connecting member 52) are made of copper (Cu).

[0052] Because the first conductive pattern (conductive pattern 20) and the terminal 40 are made of copper (Cu), even if the first conductive connection member (conductive connection member 52) is made of copper (Cu), which has a higher strength than aluminum, the first conductive connection member can be well joined or bonded to the first conductive pattern and the terminal 40. Because a material with higher strength and higher reliability can be used as the material for the first conductive connection member, the reliability of the power module 1 is improved.

[0053] The method for manufacturing a power module 1 according to the present embodiment includes preparing a circuit board 12 (S1). The circuit board 12 includes an insulating layer 13 having a main surface 13b and a conductive circuit pattern 15 provided on the main surface 13b. The conductive circuit pattern 15 includes a first conductive pattern (conductive pattern 20). The method for manufacturing a power module 1 according to the present embodiment includes joining a semiconductor element 30 to the conductive circuit pattern 15 (S2) and joining a terminal 40 to the first conductive pattern (S4). The terminal 40 includes a first end 41. The first end 41 of the terminal 40 includes a first surface 42 joined to the first conductive pattern and a second surface 43 opposite the first surface 42. The method for manufacturing a power module 1 according to the present embodiment includes bridging a first conductive connecting member between the second surface 43 of the terminal 40 and the first conductive pattern (S7).

[0054] Therefore, even if the joint 45 between the first surface 42 of the terminal 40 and the first conductive pattern (the conductive pattern 20) is peeled off from the first conductive pattern (the conductive pattern 20), the terminal 40 remains electrically connected to the first conductive pattern through the first conductive connecting member (the conductive connecting member 52), thereby improving the reliability of the power module 1.

[0055] Second Embodiment A power module 1 according to a second embodiment will be described with reference to Fig. 7. The power module 1 according to this embodiment has the same configuration as the power module 1 according to the first embodiment and achieves the same effects, but differs mainly in the following respects.

[0056] The conductive circuit pattern 15 further includes a conductive pattern 21 and a conductive pattern 22. The conductive patterns 20, 21, and 22 are spaced apart from one another. The conductive patterns 21 and 22 may be spaced apart from portions of the conductive circuit pattern 15 to which the semiconductor elements 30 and 31 are bonded. The conductive pattern 20 is, for example, a bonding conductive pad to which a terminal 40 is bonded. The conductive patterns 21 and 22 are, for example, conductive pads for testing.

[0057] The power module 1 of this embodiment further includes conductive connection members 53, 54. The conductive connection member 53 bridges between the conductive pattern 21 and the second surface 43 of the first end 41 of the terminal 40. The conductive connection member 53 is, for example, a conductive wire bonded to the conductive pattern 21 and the second surface 43 of the first end 41 of the terminal 40. The conductive connection member 54 bridges between the conductive pattern 20 and the conductive pattern 22. The conductive connection member 54 is, for example, a conductive wire bonded to the conductive pattern 20 and the conductive pattern 22.

[0058] The operation of the power module 1 of this embodiment will be described. The bonding area of ​​the joint 45 is larger than the bonding area between the terminal 40 and the conductive connection member 52 and the bonding area between the conductive connection member 52 and the conductive pattern 20. When there is no crack in the joint 45, the electrical resistance between the terminal 40 and the conductive pattern 20 via the joint 45 is smaller than the electrical resistance between the terminal 40 and the conductive pattern 20 via the conductive connection member 52. The conductive pattern 20 is electrically connected to the conductive pattern 21 through the joint 45, the conductive connection member 52, the first end 41 of the terminal 40, and the conductive connection member 53. Therefore, when a crack propagates in the joint 45, the electrical resistance between the conductive pattern 20 and the conductive pattern 21 increases. By monitoring the electrical resistance between the conductive pattern 20 and the conductive pattern 21, deterioration of the joint 45 (the extent of crack propagation) can be detected.

[0059] Furthermore, the conductive pattern 21 is electrically connected to the conductive pattern 22 through the conductive connection member 53, the first end 41 of the terminal 40, the joint 45, the conductive pattern 20, and the conductive connection member 54. Therefore, when a crack propagates in the joint 45, the electrical resistance between the conductive pattern 21 and the conductive pattern 22 also increases. By monitoring the electrical resistance between the conductive pattern 21 and the conductive pattern 22, it is possible to detect deterioration of the joint 45 (the extent of crack propagation).

[0060] In a variation of this embodiment, at least one of the conductive connection members 52, 53, 54 may be a conductive ribbon. For example, as shown in Fig. 8, the conductive connection members 52, 53 may be conductive ribbons, and the conductive connection member 54 may be a conductive wire. As shown in Fig. 9, the conductive connection member 52 may be a conductive ribbon, and the conductive connection members 53, 54 may be conductive wires. The conductive connection members 52, 53, 54 may be conductive ribbons.

[0061] The power module 1 of this embodiment has the following advantages in addition to the advantages of the power module 1 of the first embodiment.

[0062] The power module 1 of this embodiment further includes a second conductive connection member (conductive connection member 53). The conductive circuit pattern 15 includes a second conductive pattern (conductive pattern 21) spaced apart from the first conductive pattern (conductive pattern 20). The second conductive connection member bridges between the second surface 43 of the terminal 40 and the second conductive pattern.

[0063] By monitoring the electrical resistance between the first conductive pattern (conductive pattern 20) and the second conductive pattern (conductive pattern 21), deterioration of the joint 45 (the extent of crack propagation) can be detected.

[0064] The power module 1 of this embodiment further includes a third conductive connecting member (conductive connecting member 54). The conductive circuit pattern 15 includes a third conductive pattern (conductive pattern 22) spaced apart from the first conductive pattern (conductive pattern 20) and the second conductive pattern (conductive pattern 21). The third conductive connecting member bridges between the first conductive pattern and the third conductive pattern.

[0065] By monitoring the electrical resistance between the second conductive pattern (conductive pattern 21) and the third conductive pattern (conductive pattern 22), it is possible to detect deterioration (degree of crack propagation) of the joint 45 between the first surface 42 of the terminal 40 and the first conductive pattern (conductive pattern 20).

[0066] Third Embodiment A power module 1 according to a third embodiment will be described with reference to Figures 10 and 11. The power module 1 according to this embodiment has the same configuration as the power module 1 according to the first embodiment and achieves the same effects, but differs mainly in the following respects.

[0067] The conductive circuit pattern 15 further includes a conductive pattern 20b, a conductive pattern 21, and a conductive pattern 22. The conductive patterns 20, 20b, 21, and 22 are spaced apart from one another. The conductive patterns 20b, 21, and 22 may be spaced apart from portions of the conductive circuit pattern 15 to which the semiconductor elements 30 and 31 are bonded. The conductive patterns 20 and 20b are, for example, conductive bonding pads to which the terminals 40 are bonded. The conductive patterns 21 and 22 are, for example, conductive testing pads.

[0068] The terminal 40 further includes a second end 41b. The second end 41b is spaced apart from and adjacent to the first end 41. The first end 41 and the second end 41b are ends of the terminal 40 that are closest to the circuit board 12. The second end 41b of the terminal 40 includes a third surface 42b and a fourth surface 43b opposite the third surface 42b. The third surface 42b of the terminal 40 is joined to the conductive pattern 20b at a joint 45b. The joint 45b may be formed, for example, from solder, a metal microparticle sintered body such as a silver microparticle sintered body, or a resin containing a conductive filler, or may be liquid phase diffusion bonding between the third surface 42b of the terminal 40 and the conductive pattern 20b. The joint 45b may be the same as the joint 45.

[0069] The power module 1 of this embodiment further includes conductive connection members 53, 54. The conductive connection member 53 bridges between the conductive pattern 21 and the fourth surface 43b of the second end 41b of the terminal 40. The conductive connection member 53 is, for example, a conductive wire bonded to the conductive pattern 21 and the fourth surface 43b of the second end 41b of the terminal 40. The conductive connection member 54 bridges between the conductive pattern 20b and the conductive pattern 22. The conductive connection member 54 is, for example, a conductive wire bonded to the conductive pattern 20b and the conductive pattern 22.

[0070] The operation of the power module 1 of this embodiment will be described. In this embodiment, by monitoring the electrical resistance between two of the conductive patterns 20, 21, and 22, it is possible to detect deterioration of the joint 45 (degree of crack propagation) or deterioration of the joint 45b (degree of crack propagation).

[0071] Specifically, the bonding area of ​​the joint 45 is larger than the bonding area between the terminal 40 and the conductive connecting member 52 and the bonding area between the conductive connecting member 52 and the conductive pattern 20. When there is no crack in the joint 45, the electrical resistance between the terminal 40 and the conductive pattern 20 via the joint 45 is smaller than the electrical resistance between the terminal 40 and the conductive pattern 20 via the conductive connecting member 52. The conductive pattern 20 is electrically connected to the conductive pattern 21 through the joint 45, the conductive connecting member 52, the first end 41 of the terminal 40, the second end 41b of the terminal 40, and the conductive connecting member 53. Therefore, when a crack propagates in the joint 45, the electrical resistance between the conductive pattern 20 and the conductive pattern 21 increases. By monitoring the electrical resistance between the conductive pattern 20 and the conductive pattern 21, deterioration of the joint 45 (the extent of crack propagation) can be detected.

[0072] Furthermore, the conductive pattern 20 is electrically connected to the conductive pattern 22 through the joint 45, the conductive connection member 52, the first end 41 of the terminal 40, the second end 41b of the terminal 40, the joint 45b, the conductor pattern 20b, and the conductive connection member 54. Therefore, when a crack propagates in at least one of the joints 45 or 45b, the electrical resistance between the conductive pattern 20 and the conductive pattern 22 increases. By monitoring the electrical resistance between the conductive pattern 20 and the conductive pattern 22, it is possible to detect deterioration (the extent of crack propagation) of at least one of the joints 45 or 45b.

[0073] The conductive pattern 21 is electrically connected to the conductive pattern 22 through the conductive connection member 53, the second end 41b of the terminal 40, the joint 45b, the conductor pattern 20b, and the conductive connection member 54. Therefore, when a crack propagates in the joint 45b, the electrical resistance between the conductive pattern 21 and the conductive pattern 22 increases. By monitoring the electrical resistance between the conductive pattern 21 and the conductive pattern 22, it is possible to detect deterioration of the joint 45b (the extent of crack propagation).

[0074] In a modification of this embodiment, at least one of the conductive connection members 52, 53, 54 may be a conductive ribbon.

[0075] The power module 1 of this embodiment has the following advantages in addition to the advantages of the power module 1 of the first embodiment.

[0076] The power module 1 of this embodiment further includes a second conductive connecting member (conductive connecting member 53) and a third conductive connecting member (conductive connecting member 54). The conductive circuit pattern 15 includes a second conductive pattern (conductive pattern 20b), a third conductive pattern (conductive pattern 21), and a fourth conductive pattern (conductive pattern 22). The first conductive pattern (conductive pattern 20), the second conductive pattern, the third conductive pattern, and the fourth conductive pattern are spaced apart from one another. The terminal 40 includes a second end 41b spaced apart from the first end 41 and adjacent to the first end 41. The second end 41b of the terminal 40 includes a third surface 42b joined to the second conductive pattern and a fourth surface 43b opposite the third surface 42b. The second conductive connecting member bridges between the fourth surface 43b and the third conductive pattern. The third conductive connecting member bridges between the second conductive pattern and the fourth conductive pattern.

[0077] Therefore, by monitoring the electrical resistance between two of the first conductive pattern (conductive pattern 20), the third conductive pattern (conductive pattern 21), and the fourth conductive pattern (conductive pattern 22), it is possible to detect deterioration (degree of crack progression) of the joint 45 between the first surface 42 of the terminal 40 and the first conductive pattern (conductive pattern 20), or deterioration (degree of crack progression) of the joint 45b between the third surface 42b of the terminal 40 and the second conductive pattern (conductive pattern 20b).

[0078] Fourth Embodiment In this embodiment, any one of the power modules 1 according to the first to third embodiments and their modifications is applied to a power conversion device. Although the present disclosure is not limited to a specific power conversion device, the following will describe, as the fourth embodiment, a case in which any one of the power modules 1 according to the first to third embodiments and their modifications is applied to a three-phase inverter.

[0079] The power conversion system shown in Fig. 12 is composed of a power supply 100, a power conversion device 200, and a load 300. The power supply 100 is a DC power supply and supplies DC power to the power conversion device 200. The power supply 100 is not particularly limited, and may be composed of, for example, a DC system, a solar cell, or a storage battery, or may be composed of a rectifier circuit or an AC / DC converter connected to an AC system. The power supply 100 may be composed of a DC / DC converter that converts DC power output from the DC system into a predetermined power.

[0080] The power conversion device 200 is a three-phase inverter connected between the power source 100 and the load 300, and converts DC power supplied from the power source 100 into AC power and supplies the AC power to the load 300. As shown in Fig. 12 , the power conversion device 200 includes a main conversion circuit 201 that converts DC power into AC power and outputs it, and a control circuit 203 that outputs a control signal to the main conversion circuit 201 to control the main conversion circuit 201.

[0081] The load 300 is a three-phase electric motor driven by AC power supplied from the power conversion device 200. The load 300 is not limited to a specific application, but is an electric motor mounted on various electrical devices, and is used as an electric motor for, for example, a hybrid vehicle, an electric vehicle, a railroad car, an elevator, or an air conditioning device.

[0082] The power conversion device 200 will be described in detail below. The main conversion circuit 201 includes a switching element (not shown) and a freewheeling diode (not shown). The switching element switches the voltage supplied from the power supply 100, thereby converting DC power supplied from the power supply 100 into AC power and supplying it to the load 300. The main conversion circuit 201 may have a variety of specific circuit configurations. The main conversion circuit 201 of this embodiment is a two-level, three-phase full-bridge circuit, and may include six switching elements and six freewheeling diodes connected in anti-parallel to each switching element. The semiconductor elements 30 and 31 included in any of the power modules 1 of the first to third embodiments and their modifications may be used as the switching elements and freewheeling diodes of the main conversion circuit 201. The power module 202 constituting the main conversion circuit 201 may be any of the power modules 1 of the first to third embodiments and their modifications. The six switching elements are connected in series in pairs to form upper and lower arms, and each upper and lower arm constitutes one phase (U phase, V phase, and W phase) of the full-bridge circuit. The output terminals of each upper and lower arm, i.e., the three output terminals of the main conversion circuit 201, are connected to the load 300.

[0083] The main conversion circuit 201 also includes a drive circuit (not shown) that drives each switching element. The drive circuit may be built into the power module 202 or provided externally to the power module 202. The drive circuit generates drive signals that drive the switching elements included in the main conversion circuit 201 and supplies the drive signals to the control electrodes of the switching elements of the main conversion circuit 201. Specifically, in accordance with a control signal from the control circuit 203, the drive circuit outputs a drive signal that turns the switching element on and a drive signal that turns the switching element off to the control electrodes of each switching element.

[0084] The control circuit 203 controls the switching elements of the main conversion circuit 201 so that power is supplied to the load 300. Specifically, it calculates the time (on time) that each switching element of the main conversion circuit 201 should be in the on state based on the power to be supplied to the load 300. For example, the main conversion circuit 201 can be controlled by PWM control, which modulates the on time of the switching elements according to the voltage to be output to the load 300. The control circuit 203 then outputs a control command (control signal) to a drive circuit included in the main conversion circuit 201 so that an on signal is output to a switching element that should be in the on state at each time point, and an off signal is output to a switching element that should be in the off state at each time point. In accordance with this control signal, the drive circuit outputs an on signal or an off signal as a drive signal to the control electrode of each switching element.

[0085] In the power conversion device 200 of this embodiment, any of the power modules 1 of the first to third embodiments and their modifications is applied as the power module 202 included in the main conversion circuit 201. Therefore, the power conversion device 200 of this embodiment has improved reliability.

[0086] In the present embodiment, an example in which the present disclosure is applied to a two-level three-phase inverter has been described, but the present disclosure is not limited to this and can be applied to various power conversion devices. Although the present embodiment describes a two-level power conversion device, the present disclosure may be applied to a three-level power conversion device or a multi-level power conversion device. When the power conversion device supplies power to a single-phase load, the present disclosure may be applied to a single-phase inverter. When the power conversion device supplies power to a DC load or the like, the present disclosure may be applied to a DC / DC converter or an AC / DC converter.

[0087] The power conversion device to which the present disclosure is applied is not limited to cases where the load is an electric motor, and may be incorporated, for example, into a power supply device for an electric discharge machine or a laser processing machine, or a power supply device for an induction heating cooker or a contactless power supply system. The power conversion device to which the present disclosure is applied may also be used as a power conditioner for a solar power generation system, a power storage system, or the like.

[0088] The presently disclosed embodiments 1 to 4 and their modifications should be considered to be illustrative in all respects and not restrictive. Unless there is a contradiction, at least two of the presently disclosed embodiments 1 to 4 and their modifications may be combined. The scope of the present disclosure is defined by the claims, not the above description, and is intended to include all modifications within the meaning and scope of the claims.

[0089] 1 Power module, 10 Base plate, 11, 33, 34, 45, 45b Joint portion, 12 Circuit board, 13 Insulating layer, 13a, 13b Main surface, 14, 20b Conductive pattern, 15 Conductive circuit pattern, 20, 20b, 21, 22 Conductive pattern, 30, 31 Semiconductor element, 40 Terminal, 41 First end, 41b Second end, 42 First surface, 42b Third surface, 43 Second surface, 43b Fourth surface, 50, 51, 52, 53, 54 Conductive connecting member, 60 Case, 61 Sealing member, 100 Power supply, 200 Power conversion device, 201 Main conversion circuit, 202 Power module, 203 Control circuit, 300 Load.

Claims

1. a circuit board including an insulating layer having a main surface and a conductive circuit pattern provided on the main surface; a semiconductor element bonded to the conductive circuit pattern; a terminal including a first end; a first conductive connection member; the conductive circuit pattern includes a first conductive pattern; the first end of the terminal includes a first surface bonded to the first conductive pattern and a second surface opposite the first surface; The first conductive connection member bridges between the second surface and the first conductive pattern.

2. Further provided with a second conductive connection member, the conductive circuit pattern includes a second conductive pattern spaced apart from the first conductive pattern; The power module according to claim 1 , wherein the second conductive connection member bridges between the second surface and the second conductive pattern.

3. Further provided with a third conductive connection member, the conductive circuit pattern includes a third conductive pattern spaced apart from the first conductive pattern and the second conductive pattern; The power module according to claim 2 , wherein the third conductive connection member is bridged between the first conductive pattern and the third conductive pattern.

4. a second conductive connection member; a third conductive connection member; the conductive circuit pattern includes a second conductive pattern, a third conductive pattern, and a fourth conductive pattern, and the first conductive pattern, the second conductive pattern, the third conductive pattern, and the fourth conductive pattern are spaced apart from each other; the terminal includes a second end spaced from and adjacent to the first end; the second end of the terminal includes a third surface joined to the second conductive pattern and a fourth surface opposite the third surface; the second conductive connection member bridges between the fourth surface and the third conductive pattern, The power module according to claim 1 , wherein the third conductive connection member bridges between the second conductive pattern and the fourth conductive pattern.

5. The power module according to claim 1 , wherein the first conductive connection member is a conductive wire or a conductive ribbon.

6. The power module according to claim 1 , wherein the first conductive pattern, the terminal, and the first conductive connecting member are made of copper.

7. providing a circuit board including an insulating layer having a major surface and a conductive circuit pattern disposed on the major surface, the conductive circuit pattern including a first conductive pattern; bonding a semiconductor element to the conductive circuit pattern; and bonding a terminal to the first conductive pattern, the terminal including a first end, the first end of the terminal including a first surface bonded to the first conductive pattern and a second surface opposite to the first surface; a first conductive connection member extending between the second surface and the first conductive pattern;

8. a main conversion circuit including the power module according to any one of claims 1 to 6, which converts input power and outputs the converted power; a control circuit that outputs a control signal to the main conversion circuit to control the main conversion circuit.