Power module and method for manufacturing power module

Abstract

A power module (100, 100A, 100B) is provided with a semi-finished module (60) and a printed circuit board (30). The semi-finished module comprises an insulating substrate (10) and a semiconductor element (20). The insulating substrate comprises an insulating portion (11) and a conductor portion (12) disposed on the upper surface of the insulating portion. The semiconductor element is disposed on the conductor portion. The printed circuit board is disposed so as to be stacked on the semi-finished module. A through hole (38) is formed in the printed circuit board. In the insulating substrate, a positioning shape (61) is formed at a position that can be observed through the through hole when viewed from the upper surface side of the printed circuit board. The semi-finished module and the printed circuit board are connected by a bonding material (41).

Description

Power module and method for manufacturing the power module

[0001] The present disclosure relates to a power module and a method for manufacturing the power module.

[0002] Japanese Patent Laid-Open Publication No. 2009-224534 (Patent Document 1) describes a power module. In the power module described in Patent Document 1, a control circuit board is disposed above a semiconductor element mounted on an insulating substrate. The control circuit board has a signal IC and a control circuit. In the semiconductor device described in Patent Document 2, anisotropic conductive rubber is used to connect the electrodes of the control circuit board and the semiconductor element.

[0003] Furthermore, Japanese Patent No. 5788585 (Patent Document 2) describes a power module, in which electrical and mechanical connections to a control circuit board are made using bonding materials and connecting parts.

[0004] JP 2009-224534 A Japanese Patent No. 5788585 A

[0005] In the power module described in Patent Document 1, the connection between the semiconductor element and the control circuit board is ensured by contact with the anisotropic conductive rubber, so electrical resistance is prone to fluctuate depending on the contact state. Furthermore, because anisotropic conductive rubber has no adhesive strength, it is necessary to sandwich the anisotropic conductive rubber between the insulating substrate and the control circuit board. In this case, to ensure electrical continuity of the anisotropic conductive rubber, it is necessary to apply force to correct any warping of the insulating substrate or the control circuit board, but such force can crack the insulating substrate or the control circuit board. As such, anisotropic conductive rubber is difficult to apply to applications that require high reliability and carry large currents.

[0006] In the power module described in Patent Document 2, the outer shape of the control circuit board is used to determine positioning when connecting to the control circuit board, but considering the processing accuracy of the outer shape of the control circuit board, there is a risk of misalignment of the same magnitude as the size of the signal electrodes of the semiconductor element. Therefore, the power module described in Patent Document 2 needs to be provided with a positioning mechanism to avoid misalignment. However, drilling holes in the insulating substrate for the positioning mechanism raises concerns about cracking of the insulating substrate, and mounting components for positioning increases the size of the power module.

[0007] The present disclosure has been made in view of the above-mentioned problems of the conventional technology. More specifically, the present disclosure provides a power module that allows for accurate positional alignment between a semi-complete module on which a semiconductor element is mounted and a printed circuit board.

[0008] The power module of the present disclosure includes a semi-complete module and a printed circuit board. The semi-complete module has an insulating substrate and a semiconductor element. The insulating substrate has an insulating portion and a conductor portion disposed on an upper surface of the insulating portion. The semiconductor element is disposed on the conductor portion. The printed circuit board is disposed on top of the semi-complete module. A through hole is formed in the printed circuit board. The insulating substrate has a positioning shape formed in a position that can be observed through the through hole when viewed from the top side of the printed circuit board. The semi-complete module and the printed circuit board are connected with a bonding material.

[0009] According to the power module of the present disclosure, it is possible to precisely align the positional relationship between the semi-complete module and the printed circuit board.

[0010] 1. A plan view of the power module 100. A schematic cross-sectional view taken along II-II in FIG. 1. A plan view of a semi-complete module 60 included in the power module 100. A plan view of a printed circuit board 30 included in the power module 100. An enlarged view of V in FIG. 3 as viewed through a through hole 38. A cross-sectional view of the power module 100 attached to a cooler 70. An example of a power conversion device 200 using the power module 100. A manufacturing process diagram of the power module 100. An explanatory diagram for a printed circuit board connection step S3. A first example of an image captured by the observation device 82. A second example of an image captured by the observation device 82. A third example of an image captured by the observation device 82. An explanatory diagram for a sealing step S4. An enlarged view of the vicinity of a positioning shape 61 as viewed through a through hole 38 in a power module 100 according to a first modification. An enlarged view of the vicinity of a positioning shape 61 as viewed through a through hole 38 in a power module 100 according to a second modification. 13A and 13B are enlarged views of the vicinity of a positioning shape 61 in a power module 100 according to Modification 3, as seen through a through hole 38; FIG. 14B is an enlarged view of the vicinity of a positioning shape 61 in a power module 100 according to Modification 4, as seen through a through hole 38; FIG. 15C is an enlarged view of the vicinity of a positioning shape 61 in a power module 100 according to Modification 5, as seen through a through hole 38; FIG. 16A is an enlarged view of a semi-completed module 60 included in the power module 100A; FIG. 17B is an enlarged view of a portion XV in FIG. 13A, as seen through a through hole 38A; FIG. 18B is an enlarged view of a portion XVI in FIG. 13A, as seen through a through hole 38B; FIG. 19A is an explanatory view of a printed circuit board connection step S3 in the manufacturing method of the power module 100A; FIG. 19C is a first example of an image captured by an observer 82A in the manufacturing method of the power module 100A; FIG. 20B is a first example of an image captured by an observer 82B in the manufacturing method of the power module 100A; and FIG. 21C is a second example of an image captured by an observer 82A in the manufacturing method of the power module 100A. 10A is a second example of an image captured by the observation device 82B in the manufacturing method of the power module 100A. FIG. 10B is an explanatory view of a sealing step S4 in the manufacturing method of the power module 100A. FIG. 10C is a plan view of a semi-complete module 60 included in the power module 100B.20A. FIG. 20B is a plan view of the printed circuit board 30 included in the power module 100B. FIG. 20C is an enlarged view of XXII in FIG. 20 seen through a through hole 38A. FIG. 20D is an enlarged view of XXIII in FIG. 20 seen through a through hole 38B. FIG. 20E is an explanatory view of a printed circuit board connecting step S3 in the manufacturing method of the power module 100B. FIG. 20F is a first example of an image taken by the imaging device 62A in the manufacturing method of the power module 100B. FIG. 20F is a first example of an image taken by the imaging device 62B in the manufacturing method of the power module 100B. FIG. 20G is an explanatory view of a sealing step S4 in the manufacturing method of the power module 100B.

[0011] The details of the embodiments of the present disclosure will be described with reference to the drawings. In the following drawings, the same or corresponding parts are designated by the same reference numerals, and redundant descriptions will not be repeated.

[0012] First Embodiment A power module according to a first embodiment will be described. The power module according to the first embodiment is designated as a power module 100.

[0013] (Configuration of Power Module 100) FIG. 1 is a plan view of the power module 100. FIG. 2 is a schematic cross-sectional view taken along line II-II in FIG. 1. The left-right direction in FIG. 2 is the X direction, the direction perpendicular to the paper surface in FIG. 2 is the Y direction, and the up-down direction in FIG. 2 is the Z direction. Furthermore, the output terminal 37c is not visible because it overlaps with the input terminal 37a in the cross section taken along line II-II in FIG. 1, but in FIG. 2, the output terminal 37c is schematically shown shifted in the Z direction. FIG. 3 is a plan view of a semi-complete module 60 included in the power module 100. FIG. 4 is a plan view of a printed circuit board 30 included in the power module 100. As shown in FIGS. 1 to 4, the power module 100 includes an insulating substrate 10, a semiconductor element 20, the printed circuit board 30, a resin 40, a bonding material 41, and a sealing material 50. The insulating substrate 10 and the semiconductor element 20 may be collectively referred to as a semi-complete module 60. The number of semiconductor elements 20 is, for example, four, but is not limited to this number. The power module 100 is used in electronic devices such as inverters, converters, and servo amplifiers.

[0014] The insulating substrate 10 is configured such that a conductor portion 12 and a conductor portion 13, which serve as electrical connections, are bonded to the upper and lower surfaces of an insulating portion 11, respectively. The insulating portion 11 is made of a material such as aluminum nitride (AlN), alumina (Al ２ O ３ ), silicon nitride (Si ３ N ４ The insulating portion 11 may be an organic component layer whose main component is a resin such as polyimide or epoxy. The longitudinal direction of the insulating substrate 10 is along the X direction.

[0015] The insulating substrate 10 has a first end face and a second end face in the longitudinal direction. The second end face is the face opposite to the first end face. The first end face is the end face of the insulating substrate 10 on the lower side in FIG. 3. The second end face is the end face of the insulating substrate 10 on the upper side in FIG. 3. The insulating substrate 10 has a central portion 10a, an end region 10b, and an end region 10c in the longitudinal direction. The central portion 10a is located in the center of the insulating substrate 10 in the longitudinal direction. The end region 10b is located closer to the first end face than the central portion 10a, and the end region 10c is located closer to the second end face than the central portion 10a.

[0016] The conductor portion 12 is disposed on the upper surface of the insulating substrate 10. The conductor portion 12 includes a conductor island 12a, a conductor island 12b, and a conductor island 12c. The conductor islands 12a, 12b, and 12c are electrically insulated from one another. Different potentials are applied to the conductor islands 12a and 12b, respectively. The conductor portion 13 is disposed on the lower surface of the insulating substrate 10. The conductor portions 12 and 13 are made of, for example, copper (Cu), aluminum (Al), nickel, etc. The conductor portions 12 and 13 may be formed of a single metal material, or may be plated with gold (Au), silver (Ag), etc.

[0017] The thickness of the insulating portion 11 and the thickness of the pattern electrodes are designed taking into consideration the heat dissipation, insulation, bonding reliability, etc. of the power module. The thickness of the insulating portion 11 is, for example, 0.001 mm or more and 3 mm or less. The thickness of the conductor portion 12 and the conductor portion 13 are 0.001 mm or more and 5 mm or less. In this embodiment, aluminum nitride having a thickness of 0.05 mm is used as the insulating portion 11, and copper having a thickness of 0.1 mm is used as the conductor portion 12 and the conductor portion 13.

[0018] However, it goes without saying that the effects of the power module 100 can be obtained even if the thicknesses of the insulating portion 11, the conductor portion 12, and the conductor portion 13 are different from those described above. The thicknesses of the conductor portion 12 and the conductor portion 13 may be the same as or different from each other.

[0019] The type of semiconductor element 20 is not particularly limited, but may be a metal oxide semiconductor field effect transistor (MOSFET), an insulated gate bipolar transistor (IGBT), a diode, or the like. The shape of the semiconductor element 20 in a plan view is, for example, a rectangle with a side length of, for example, 1 mm or more and 20 mm or less. The material of the semiconductor element 20 may be, for example, silicon (Si), silicon carbide (SiC), gallium nitride (GaN), diamond, or other so-called wide bandgap semiconductor materials having a wider bandgap than silicon. A semiconductor element 20 using a wide bandgap semiconductor material can achieve faster switching and lower on-resistance than a semiconductor element 20 using silicon. Because a semiconductor element 20 using a wide bandgap semiconductor material exhibits higher performance than a semiconductor element 20 using silicon, the size of the semiconductor element 20 can be made smaller than a semiconductor element 20 using silicon, and therefore the size of the power module 100 can also be made smaller.

[0020] The semiconductor element 20 has an electrode 21 and an electrode 22 on its upper surface. The electrode 21 is, for example, a source electrode. The electrode 22 is, for example, a gate electrode. A main circuit current flows through the electrode 21 (source electrode), while a weak signal current for driving the semiconductor element 20 flows through the electrode 22 (gate electrode). Therefore, the area of ​​the electrode 22 is smaller than the area of ​​the electrode 21. The size of the electrode 21 is, for example, 1 mm square or more and 10 mm square or less. The size of the electrode 22 is, for example, 0.1 mm square or more and 2 mm square or less.

[0021] The semiconductor element 20 is disposed on the conductor portion 12 via a bonding material 23. This bonds the underside of the semiconductor element 20 to the conductor portion 12. The bonding material 23 may be any of a variety of materials, including solder primarily composed of tin (Sn), sintered metal materials primarily composed of gold, silver, or copper, intermetallic compounds formed by alloying copper and tin, and conductive adhesives formed by mixing particles of silver, nickel, or the like into resin. The bonding material 23 may be supplied in a variety of forms, including paste, sheet, and powder. It goes without saying that the effects of the power module 100 can be achieved regardless of the form in which the bonding material 23 is supplied. In this embodiment, a silicon carbide MOSFET serving as the semiconductor element 20 is bonded to the conductor portion 12 using 0.1 mm-thick solder as the bonding material 23. It goes without saying that the effects of the power module 100 can be achieved even when other types of semiconductor elements and bonding materials are used.

[0022] The semiconductor elements 20 arranged on the conductor island 12a may be referred to as semiconductor elements 20A and 20C, and the semiconductor elements 20 arranged on the conductor island 12b may be referred to as semiconductor elements 20B and 20D.

[0023] The printed circuit board 30 is disposed above the insulating substrate 10 and the semiconductor element 20. The printed circuit board 30 is, for example, a single-layer or multi-layer printed circuit board. The type of printed circuit board 30 is, for example, a paper phenolic board, a paper epoxy board, a glass epoxy board, a ceramic board, a composite board, or the like. The printed circuit board 30 has a plurality of electrodes 31 on its underside. Of the plurality of electrodes 31, the one connected to the conductor island 12a or the conductor island 12b is referred to as electrode 31a. Of the plurality of electrodes 31, the one connected to electrode 21 is referred to as electrode 31b. Of the plurality of electrodes 31, the one connected to electrode 22 is referred to as electrode 31c. Of the plurality of electrodes 31, the one connected to electrode 22 is referred to as electrode 31d.

[0024] The printed circuit board 30 has a plurality of lands on its top surface. A driver IC 32 and electronic components 33 are connected to the lands with a bonding material 34. The bonding material 34 is, for example, solder, but may be other materials (e.g., sintered metal material, intermetallic compound, conductive adhesive, etc.). The position where the driver IC 32 is disposed is not particularly specified, but it is preferably vertically above the semiconductor element 20 from the viewpoint of reducing wiring resistance and wiring inductance.

[0025] The printed circuit board 30 includes a driver circuit. The driver circuit is a circuit section for generating signals directly input to the semiconductor element 20. The driver circuit includes a driver IC 32 and electronic components 33. In addition to the driver IC 32 and electronic components 33, the driver circuit also includes peripheral elements, such as gate resistors, diodes, and connectors. The peripheral elements are capacitors and pull-up / pull-down resistors for stabilizing the power supply of the driver IC 32. The gate resistors and diodes are part of the main circuit and are located in close proximity to the semiconductor element 20 to determine whether the gate of the semiconductor element 20 is turned on or off. The connectors are electrical connections for supplying power and signals to the driver IC 32. The driver circuit incorporates, for example, a pulse transformer or a photocoupler as an insulating section for insulating the high-voltage system potential, which is the potential of the main circuit, from the low-voltage system potential, which is the potential of the control section for controlling the main circuit. Note that the driver IC 32 may also include an insulating section such as a photocoupler. A signal buffer IC and electronic components constituting its peripheral circuit may also be mounted on the printed circuit board 30. The potential of the high voltage system and the potential of the low voltage system are insulated for safety. The drive circuit is a circuit part that serves as an interface between the two potentials of the high voltage system and the low voltage system.

[0026] The printed circuit board 30 may further include all or part of a control circuit and a power supply circuit. The control circuit is a circuit section that determines the signal to be sent to the drive IC 32 in response to device command values ​​and signals from various sensors. The power supply circuit is a circuit section that generates power supply power for the drive IC 32, power to drive the gates of the semiconductor elements 20, and power supply power for the microcontroller. The power supply circuit includes a power supply IC and peripheral elements of the power supply IC. The peripheral elements of the power supply IC include, for example, a transformer.

[0027] The control circuit includes a microcontroller, peripheral elements of the microcontroller, a connector, etc. The connector serves as an electrical connection with the drive circuit. The control circuit may include a protection circuit that shuts down the operation of the main circuit based on signals from various sensors. The printed circuit board 30 may also include a communication IC and peripheral circuits for the communication IC for communicating with the outside. The control circuit is a low-voltage system.

[0028] The printed circuit board 30 has a wiring pattern for connecting the semiconductor element 20 connected to the electrodes 31 and the components mounted on the lands. The electrodes 31, lands, and wiring pattern are made of, for example, copper or a copper alloy. The electrodes 31 and lands may be plated with a noble metal such as tin, gold, or silver to improve bonding strength.

[0029] The wiring pattern includes wiring patterns 36a, 36b, and 36c arranged inside the printed circuit board 30. The wiring pattern 36a is electrically connected to the electrode 31a connected to the conductor island 12a. The wiring pattern 36b is electrically connected to the electrode 31b connected to the electrode 21 of the semiconductor element 20A (semiconductor element 20C) and the electrode 31a connected to the conductor island 12b. The wiring pattern 36c is electrically connected to the electrode 31b and the electrode 31c connected to the electrode 21 of the semiconductor element 20B (semiconductor element 20D).

[0030] The wiring patterns 36a and 36c are arranged so that at least a portion of them overlap in the Z direction inside the printed circuit board 30. The larger the area over which the wiring patterns 36a and 36c overlap, the more preferable it is. Furthermore, it is preferable that the wiring patterns arranged inside the printed circuit board 30 are arranged so that at least a portion of them overlap with the conductor portion 12 in the Z direction.

[0031] The wiring pattern of the printed circuit board 30 is formed, for example, from copper or a copper alloy. The thickness of the wiring pattern of the printed circuit board 30 through which the main current flows is, for example, 105 μm or more. A current of 100 A or more may flow through the wiring pattern. If the wiring pattern is thin when a large current flows, the amount of heat generated increases, possibly exceeding the glass transition temperature of the resin material used in the printed circuit board 30, resulting in reduced connection reliability. In this embodiment, by setting the thickness of the wiring pattern of the printed circuit board 30 through which the main current flows to 500 μm, the amount of heat generated is reduced to less than one-tenth of that of a typical printed circuit board (approximately 35 μm thick). Note that a similar reduction in heat generation can also be achieved by stacking multiple thin wiring patterns. However, in this case, current distribution occurs, resulting in temperature differences between each layer. Therefore, considerations must be taken into account when using this method, such as the need to tightly connect each layer to suppress such current distribution.

[0032] The printed circuit board 30 has an input terminal 37a, an output terminal 37b, and an input terminal 37c. Main current flows through these terminals. The printed circuit board 30 has a signal terminal 37d. A signal for operating the driving IC 32 and a current for supplying power to the driving IC 32 flow through the signal terminal 37d. The input terminal 37a is electrically connected to the wiring pattern 36a. The output terminal 37b is electrically connected to the wiring pattern 36b. The input terminal 37c is electrically connected to the wiring pattern 36c. The input terminal 37a, the output terminal 37b, the input terminal 37c, and the signal terminal 37d protrude from the printed circuit board 30. The input terminal 37a, the output terminal 37b, the input terminal 37c, and the signal terminal 37d are used for external connection of the power module 100.

[0033] The input terminal 37a, the output terminal 37b, the input terminal 37c, and the signal terminal 37d are formed, for example, by fabricating the printed circuit board 30 and then removing a resin portion of the printed circuit board 30. The input terminal 37a, the output terminal 37b, the input terminal 37c, and the signal terminal 37d may be protruded from the printed circuit board 30 by mounting a copper plate on the upper or lower surface of the printed circuit board 30. Alternatively, the input terminal 37a, the output terminal 37b, the input terminal 37c, and the signal terminal 37d may be formed by mounting pins on the printed circuit board 30. Through holes may be formed in the input terminal 37a, the output terminal 37b, and the input terminal 37c, as necessary. A variety of connection methods can be used to connect the input terminal 37a, the output terminal 37b, the input terminal 37c, and the signal terminal 37d to external terminals such as a capacitor or a rotating electrical machine. Examples of connection methods include TIG (Tungsten Inert Gas) welding, laser welding, and screw fastening.

[0034] The resin 40 is disposed on the upper surface of the semiconductor element 20 and on the conductor portion 12. The upper surface of the resin 40 is in contact with the printed circuit board 30. The lower surface of the resin 40 is in contact with the upper surface (conductor portion 12) of the insulating substrate 10 or the upper surface of the semiconductor element 20. A through hole extending in the Z direction is formed in the resin 40. A bonding material 41 is disposed in this through hole. From another perspective, the periphery of the bonding material 41 is surrounded by the resin 40.

[0035] The bonding material 41 connects the electrode 31a to the conductor island 12a or the conductor island 12b, connects the electrode 31b to the electrode 21, connects the electrode 31c to the electrode 22, and connects the electrode 31d to the conductor island 12c. As with the bonding material 23, various materials such as solder, a sinterable metal material, an intermetallic compound, or a conductive adhesive are used for the bonding material 41.

[0036] By connecting the electrode 31, the electrode 21, and the conductor 12 with the bonding material 41, current flows as follows: Current supplied from the input terminal 37a passes through the wiring pattern 36a and flows to the semiconductor elements 20A and 20C via the electrode 31a, the bonding material 41, and the conductor island 12a. Next, the current that has flowed through the semiconductor elements 20A and 20C flows through the wiring pattern 36b via the electrode 21, the bonding material 41, and the electrode 31b. A portion of the current flowing through the wiring pattern 36b flows from the output terminal 37b to the outside of the power module 100, and the remainder of the current flowing through the wiring pattern 36b flows to the semiconductor elements 20B and 20D via the electrode 31a, the bonding material 41, and the conductor island 12b. The current that has flowed through the semiconductor elements 20B and 20D flows through the wiring pattern 36c via the electrode 21, the bonding material 41, and the electrode 31b, and then flows from the input terminal 37c to the outside of the power module 100.

[0037] Because of the current flow described above, semiconductor elements 20A and 20C are connected in parallel and function as a single element by performing the same switching operation. This is also true for semiconductor elements 20B and 20D. The parallel connection reduces the current flowing through each semiconductor element 20, thereby reducing heat generation. Furthermore, because of the current flow described above, the direction of current flowing through wiring pattern 36a is opposite to the direction of current flowing through wiring pattern 36c. Therefore, the overlapping portion of wiring pattern 36a and wiring pattern 36c functions as a parallel plate, making it difficult for magnetic flux to enter between wiring pattern 36a and wiring pattern 36c. As a result, inductance is reduced. The greater the overlap between wiring pattern 36a and wiring pattern 36c, the greater the inductance reduction effect. Note that the parallel plate structure described above does not need to be contained solely within the printed circuit board 30. That is, the effect of reducing inductance can be obtained by reversing the direction of the current flowing through the insulating substrate 10 and the direction of the current flowing through the conductor portion 12 .

[0038] The wiring pattern 36a is connected to the insulating substrate 10 (conductor island 12a) at a joint 12aa, and the wiring pattern 36b is connected to the insulating substrate 10 (conductor island 12b) at a joint 12ba. Therefore, the wiring patterns 36a and 36b are cooled via a cooler 70 connected to the conductor 13 by a joint material 71. The wiring pattern 36c does not need to be connected to the insulating substrate 10, and its temperature is likely to rise.

[0039] However, by connecting the wiring pattern 36c to the insulating substrate 10 (conductor island 12c) at the joint 12ca, the wiring pattern 36c is also cooled via the cooler 70. Because the wiring pattern is cooled efficiently in this manner, the thickness of the wiring pattern can be reduced, thereby making it possible to reduce the cost and weight of the power module 100. Note that the number of joints 12aa, 12ba, and 12ca is not particularly limited. Furthermore, because the wiring pattern can be cooled by thickening the terminals, etc., it is not essential that the wiring pattern (wiring pattern 36c) be connected to the insulating substrate 10 (conductor island 12c).

[0040] The resin 40 ensures a gap between the insulating substrate 10 (conductor portion 12) and the printed circuit board 30 and a gap between the semiconductor element 20 and the printed circuit board 30. The resin 40 prevents short circuits between the bonding materials 41 that connect different electrodes. The resin 40 provides insulation between locations where a high potential difference occurs (for example, between the printed circuit board 30 and the semiconductor element 20 or between the printed circuit board 30 and the insulating substrate 10). The resin 40 also relieves thermal stress applied to the bonding materials 41 when the power module 100 is operating. The thickness, shape, application position, etc. of the resin 40 are determined appropriately taking into account the required pressure resistance, etc.

[0041] The resin 40 may be any of various resins, such as PTFE (polytetrafluoroethylene), PI (polyimide), and PPS (polyphenylenesulfide). Other resins may also be used as the resin 40 as long as they provide similar effects. The resin 40 may be provided directly above the semiconductor element 20 by forming through holes in the resin 40 processed into a sheet shape that correspond to the electrodes 21 and 22. Alternatively, the resin 40 may be provided by applying a liquid resin 40 to the edges of the electrodes of the semiconductor element 20 and allowing it to harden, or by molding the resin 40 into a desired shape by injection molding, transfer molding, or the like and providing it between the insulating substrate 10 and the printed circuit board 30 and between the semiconductor element 20 and the printed circuit board 30. When a curable resin, such as epoxy resin, is used as the resin 40, the resin 40 may be provided in a semi-cured state on the semiconductor element 20, and then the bonding material 41 may be provided and heated, thereby simultaneously heating the resin 40 and bonding with the bonding material 41.

[0042] In this embodiment, through holes were formed in a 1 mm thick sheet of PTFE to serve as resin 40. In this case, the diameter of the through holes above electrode 21 was set to 5 mm, and the diameter of the through holes above electrode 22 was set to 1 mm. In addition, adhesive processing was performed on the upper and lower surfaces of the sheet of PTFE to prevent it from moving from above semiconductor element 20 and insulating substrate 10. The adhesive processing may be performed by supplying an adhesive, or may be performed using double-sided tape.

[0043] The electrode 31 is an electrode formed on the printed circuit board 30, and therefore can be easily enlarged in size. On the other hand, the electrode 22 is difficult to enlarge in size due to restrictions on the size of the semiconductor element 20, restrictions on the surface potential pattern, and the like, and the electrode 22 tends to be the smallest inside the power module 100. Therefore, alignment of the electrodes of the printed circuit board 30 and the electrodes of the semiconductor element 20 is important, and from this perspective, there are appropriate shapes for the resin 40 and the electrode 31.

[0044] The sealing material 50 serves to seal the power module 100. More specifically, the sealing material 50 seals the insulating substrate 10, the semiconductor element 20, the printed circuit board 30, and the resin 40 by surrounding them. This provides the power module 100 with moisture resistance, antifouling properties, a thermal stress relaxation function, and insulation properties. However, the input terminal 37a, the output terminal 37b, and the input terminal 37c protrude from the sealing material 50. Furthermore, the conductor portion 13 may be exposed from the sealing material 50.

[0045] The sealing material 50 is formed by, for example, transfer molding. The sealing material 50 may also be formed by a method other than transfer molding, for example, compression molding. Depending on the application of the power module 100, the power module 100 may not have the sealing material 50.

[0046] The components of the sealing material 50 are preferably different from the components of the resin 40. The sealing material 50 may contain an inorganic filler in order to reduce the linear expansion coefficient of the sealing material 50 and the amount of shrinkage during hardening. In this embodiment, the inorganic filler is, for example, silica (SiO ２ ) The linear expansion coefficient of epoxy resin is approximately 20 ppm / K to 40 ppm / K, while the linear expansion coefficient of the ceramic used in the insulating portion 11, such as aluminum nitride, is 4.5 ppm / K. Therefore, thermal stress caused by the difference in the linear expansion coefficients of the sealing material 50 and the insulating portion 11 may cause peeling between the sealing material 50 and the insulating portion 11. By including an inorganic filler in the sealing material 50, the linear expansion coefficient of the sealing material 50 is reduced, and the thermal stress is also reduced, thereby suppressing peeling between the sealing material 50 and the insulating portion 11.

[0047] By including an inorganic filler in the sealing material 50, the elastic modulus of the sealing material 50 increases, which may increase thermal stress. To address this situation, it is preferable to make the elastic modulus of the resin 40 smaller than that of the sealing material 50. By having a soft resin 40 interposed between the sealing material 50 and the bonding material 41, thermal stress caused by displacement of the sealing material 50 due to temperature changes is less likely to be transmitted to the bonding material 41.

[0048] A through hole 38 is formed in the printed circuit board 30. The through hole 38 penetrates the printed circuit board 30 in the thickness direction (Z direction). The through hole 38 is formed by cutting or laser processing so as to have a diameter of, for example, approximately 2 mm. The size of the through hole 38 is sufficient as long as it can be observed by the observation device 82 (described later) and is large enough to allow the sealing material 50 to flow through it. Therefore, as long as this requirement is satisfied, the diameter of the through hole 38 may be greater than 2 mm. The through hole 38 does not have to be a round hole, but may be a quadrangular hole such as a square or rectangular hole. The through hole 38 may also be a through hole, in which the inner wall surface of the hole is plated after drilling to ensure electrical conductivity between layers of the printed circuit board 30.

[0049] FIG. 5 is an enlarged view of V in FIG. 3 as viewed through the through hole 38. As shown in FIG. 5, the semi-complete module 60 has a positioning feature 61. The positioning feature 61 is, for example, a boundary line between a notch formed in the conductor island 12b and the insulating part 11. The positioning feature 61 has, for example, a first line 61a and a second line 61b. The first line 61a extends along the X direction. The second line 61b extends along the Y direction. The first line 61a and the second line 61b may extend in different directions. In the above example, the first line 61a and the second line 61b form a right angle, but they may also form an acute angle or an obtuse angle. The first line 61a does not have to be parallel to the X direction, and the second line 61b does not have to be parallel to the Y direction. The first line 61a and the second line 61b do not have to be straight lines.

[0050] The positioning shape 61 (notch) is formed, for example, when the conductor portion 12 is formed, and does not require additional processing. However, as long as it does not split the insulating portion 11, it may be formed by additional processing such as cutting the conductor portion 12. The positioning shape 61 is disposed, for example, in the central portion 10a, at a location where the conductor island 12a and the conductor island 12b are separated.

[0051] The positioning shape 61 is not limited to the boundary line between the conductor portion 12 and the insulating portion 11. The positioning shape 61 may be, for example, the boundary line between the conductor portion 12 and the semiconductor element 20 (the outline of the semiconductor element 20). The positioning shape 61 may be a marking formed on the insulating portion 11 or a marking formed on the conductor portion 12. The marking is formed, for example, with a laser. The marking may be a specific character, a shape such as a circle or a rectangle, a straight line, a curve, or a combination thereof.

[0052] Fig. 6 is a cross-sectional view of the power module 100 attached to a cooler 70. As shown in Fig. 6, the power module 100 may further include a cooler 70. The cooler 70 is connected to the conductor portion 13 by a bonding material 71. As with the bonding material 23, various materials such as solder, a sinterable metal material, an intermetallic compound, and a conductive adhesive are used for the bonding material 71.

[0053] FIG. 7 shows an example of a power conversion device 200 using the power module 100. As shown in FIG. 7, the power conversion device 200 has an inverter circuit 210. The inverter circuit 210 is mounted, for example, on an electric vehicle. The inverter circuit 210 has terminals 210a and 210b. The positive side (P potential) of an on-board battery 220 is connected to terminal 210a, and the negative side (N potential) of the on-board battery 220 is connected to terminal 210b. In addition, an input capacitor 230 that smooths the on-board battery 220 is connected to the input stage of the power conversion unit, i.e., between terminals 210b and 210b.

[0054] The inverter circuit 210 has three pairs of semiconductor elements 211 and 212 connected in series. These three pairs form a three-phase AC full-bridge circuit, constituting one three-phase AC. The power conversion device 200 has two inverter circuits 210, so that the three-phase AC is configured twice, making it a dual three-phase power conversion device. The semiconductor element 211 is an upper arm semiconductor element connected to the terminal 210a side, i.e., the positive side of the on-board battery 220. The semiconductor element 212 is a lower arm semiconductor element connected to the terminal 210b side, i.e., the negative side of the on-board battery 220. The potential at the point where the upper arm semiconductor elements and the lower arm semiconductor elements are connected is sometimes referred to as the AC potential.

[0055] The inverter circuit 210 is connected to the rotating electric machine 240 via AC wiring connected between the semiconductor elements 211 and 212. The inverter circuit 210 converts DC current from the on-board battery 220 into AC current by switching the semiconductor elements 211 and 212, and drives the rotating electric machine 240 through the AC wiring. Furthermore, AC current generated in the rotating electric machine 240 by regenerative braking or the like is supplied to the inverter circuit 210 via the AC wiring, converted into DC current in the inverter circuit 210, smoothed by the input capacitor 230, and stored in the on-board battery 220.

[0056] The power conversion device 200 includes a drive circuit 250, a control circuit 260, and a power supply circuit 270. The drive circuit 250 and the control circuit 260 output appropriate signals for switching the semiconductor elements 211 and 212, and perform control so that the target drive frequency and torque of the rotating electric machine 240 are obtained. Furthermore, when the drive circuit 250 and the control circuit 260 detect damage to the rotating electric machine 240 or an abnormal current, they perform control so as to stop the drive and power supply of the inverter circuit 210 in a safe manner. These controls are performed based on the current value detected by a current sensor and the signal voltage converted from the current value. The power supply circuit 270 generates power for the drive circuit 250 and the control circuit 260.

[0057] The power module 100 includes a semiconductor element 211, a semiconductor element 212, and a drive circuit 250. More specifically, the semiconductor element 211 is made up of semiconductor elements 20A and 20C, the semiconductor element 212 is made up of semiconductor elements 20B and 20C, and the drive circuit 250 is made up of a drive circuit. The semiconductor element 211 and terminal 210a are connected via an input terminal 37a, the semiconductor element 212 and terminal 210b are connected via an input terminal 37c, and the semiconductor elements 211 and 212 are connected to the AC wiring via an output terminal 37b. The power module 100 may further include a control circuit 260 and a power supply circuit 270.

[0058] (Manufacturing Method of Power Module 100) Fig. 8 is a manufacturing process diagram of the power module 100. As shown in Fig. 8, the manufacturing method of the power module 100 includes a semiconductor element connecting step S1 and a circuit component connecting step S2.

[0059] In the semiconductor element connecting step S1, the semiconductor element 20 is bonded to the conductor portions 12 (conductor islands 12a and 12b) with a bonding material 23. This prepares a semi-finished module 60. The circuit component connecting step S2 is performed in parallel with the semiconductor element connecting step S1. In the circuit component connecting step S2, the driver IC 32, electronic components 33, and other components are bonded to the printed circuit board 30 with a bonding material 34.

[0060] The manufacturing method of the power module 100 further includes a printed circuit board connecting step S3. When connecting the printed circuit board 30 to the semi-completed module 60, relative positional accuracy between the semi-completed module 60 and the printed circuit board 30 is important. FIG. 9 is an explanatory diagram of the printed circuit board connecting step S3. As shown in FIG. 9, in the printed circuit board connecting step S3, first, the semi-completed module 60 is attached to a fixing jig 80. The fixing jig 80 is made of a material such as aluminum, iron, copper, or ceramic. The fixing jig 80 is produced by cutting or casting, for example.

[0061] The fixing jig 80 has a groove 80a. The groove 80a is, for example, slightly larger than the outer shape of the semi-completed module 60. The semi-completed module 60 is placed on the bottom surface of the groove 80a. The fixing jig 80 may have a position restriction mechanism 80b. The position restriction mechanism 80b is provided, for example, on one of the side surfaces of the groove 80a parallel to the XZ plane and one of the side surfaces of the groove 80a parallel to the YZ plane. The position restriction mechanism 80b pushes the semi-completed module 60 toward the opposing side surface of the groove 80a. This allows misalignment of the semi-completed module 60 to be suppressed in advance to the manufacturing accuracy of the outer shape of the semi-completed module 60. A suction hole may be formed in the bottom surface of the groove 80a, and the semi-completed module 60 is adsorbed to the fixing jig 80 and fixed by sucking air through the hole.

[0062] In the printed circuit board connecting step S3, second, the bonding material 41 is supplied to the semi-completed module 60. In this embodiment, the resin 40 is used as the method for supplying the bonding material 41. However, only the bonding material 41 may be supplied. Alternatively, the resin 40 may be supplied after the bonding material 41 is supplied. In the printed circuit board connecting step S3, third, the printed circuit board 30 is transported to a predetermined temporary position by the transport arm 81. The predetermined temporary position is a position where, in design, the positioning shape 61 and the alignment lines (alignment lines 38a and 38b) of the observation device 82 coincide with each other. The transport arm 81 preferably transports the printed circuit board 30 by partially vacuum-adsorbing it. The transport arm 81 may also transport the printed circuit board 30 while gripping grippable components of the printed circuit board 30. In this state, the printed circuit board 30 does not come into contact with the bonding material 41 and waits at a position spaced a given height from the semi-completed module 60 in the Z direction. When the printed circuit board 30 is transported, the longitudinal and lateral directions of the printed circuit board 30 are adjusted to coincide with the alignment lines 38 a and 38 b, respectively. More specifically, the printed circuit board 30 is rotated so that the alignment lines 38 a and 38 b coincide with the directions of the outline of the printed circuit board 30 along the longitudinal and lateral directions, respectively. The printed circuit board 30 may be rotated so that the alignment lines 38 a and 38 b coincide with the directions of the wiring pattern extending in the longitudinal and lateral directions, respectively, of the printed circuit board 30. Alternatively, silk-screened lines may be provided on the printed circuit board 30 near the through-holes 38 along the longitudinal and lateral directions of the printed circuit board 30, and the printed circuit board 30 may be rotated so that the alignment lines 38 a and 38 b coincide with the silk-screened lines along the longitudinal and lateral directions of the printed circuit board 30, respectively.

[0063] In this standby state, the observer 82 observes the positioning feature 61 located below the through-hole 38 from the upper surface of the printed circuit board 30. The observer 82 is preferably an industrial digital camera, but may be any other camera, or may be a device for visual observation by a person, such as a microscope. In this example, the observer 82 is a digital camera. The observer 82 can grasp the relative positional relationship between the alignment lines 38a and 38b and the positioning feature 61 (first line 61a, second line 61b). In an ideal situation, the alignment lines 38a and 38b coincide with the first line 61a and second line 61b, respectively, as shown in FIG. 5 .

[0064] 10A is a first example of an image captured by the observer 82. FIG. 10B is a second example of an image captured by the observer 82. FIG. 10C is a third example of an image captured by the observer 82. As shown in FIGS. 10A to 10C , if the relative positions of the printed circuit board 30 and the semi-completed module 60 are misaligned, the alignment lines 38 a and 38 b will not coincide with the first line 61 a and the second line 61 b, respectively. In this case, the amount of misalignment, i.e., the direction and distance in which the printed circuit board 30 should be moved or the angle and direction in which the printed circuit board 30 should be rotated, can be determined based on how the positioning shape 61 is viewed by the observer 82. The controller 83 controls the transfer arm 81 based on this positioning amount to adjust the position of the printed circuit board 30.

[0065] In the printed circuit board connection step S3, fourthly, the printed circuit board 30 is lowered to bring the printed circuit board 30 into contact with the bonding material 41, and then the transfer arm 81 releases the printed circuit board 30 from the printed circuit board 30. Thereafter, pressure is applied from the upper surface of the printed circuit board 30 as needed, and heat is also applied as needed. As a result, after a predetermined time has passed, the printed circuit board 30 and the semi-completed module 60 are bonded together with the bonding material 41. It is also possible to apply pressure to the printed circuit board 30 with the transfer arm 81 without releasing the printed circuit board 30 from the transfer arm 81.

[0066] The manufacturing method of the power module 100 further includes an encapsulating step S4. FIG. 11 is an explanatory diagram of the encapsulating step S4. In FIG. 11, the flow of the encapsulating material 50 is indicated by arrows. As shown in FIG. 11, in the encapsulating step S4, for example, transfer molding is performed. In the encapsulating step S4, first, the printed circuit board 30 and the semi-completed module 60, which have been joined to each other with the joining material 41 in the printed circuit board connecting step S3, are placed inside a mold 84.

[0067] In the sealing step S4, secondly, the liquefied encapsulant 50 is poured into the mold 84 through the resin gate 84a. The resin gate 84a is provided, for example, at the upper part of the inner surface of the mold 84 in the X direction. The liquefied encapsulant 50 branches off toward the lower and upper surfaces of the printed circuit board 30 and flows along the X direction. In the power module 100, the gap between the printed circuit board 30 and the semi-finished module 60 is approximately 1 mm, which is the thickness of the resin 40. Therefore, the cross-sectional area of ​​the resin flow is relatively larger on the upper surface side of the printed circuit board 30, where the component height is 2 mm or more and a gap to the mold 84 is also secured. Therefore, in conjunction with the position of the resin gate 84a, the liquefied encapsulant 50 flows mainly along the upper surface side of the printed circuit board 30.

[0068] The liquefied sealant 50 flows mainly on the upper surface side of the printed circuit board 30, but part of the liquefied sealant 50 passes through the through holes 38 and flows from the upper surface side of the printed circuit board 30 to the lower surface side of the printed circuit board 30. Therefore, when the sealing step S4 is completed, the sealant 50 has filled the through holes 38, and the sealant 50 has filled the upper surface, lower surface and periphery of the printed circuit board 30.

[0069] The manufacturing method of the power module 100 further includes a cooler connecting step S5. In the cooler connecting step S5, the cooler 70 is joined to the conductor portion 13 by the joining material 71.

[0070] When solder is used for the bonding materials 23, 34, 41, and 71, the process temperature in each step is important. For example, when connecting the cooler 70 using the bonding material 71 in the cooler connecting step S5, the process temperature must be set so that the bonding materials 23, 34, and 41 do not melt. This is because if the bonding materials 23, 34, and 41 melt inside the sealing material 50, the volume expansion of the bonding materials 23, 34, and 41 due to the melting may cause the sealing material 50 to crack.

[0071] When connecting the semi-completed module 60 to the printed circuit board 30 in the printed circuit board connection step S3, it is preferable that the bonding materials 23 and 34 do not melt in order to prevent the semiconductor elements 20, the driver ICs 32, the electronic components 30, etc. from moving and becoming detached. Furthermore, when connecting the semi-completed module 60 to the printed circuit board 30 in the printed circuit board connection step S3, pressure may be applied to the semi-completed module 60 or the printed circuit board 30 to reduce warping. If the bonding materials 23 and 34 melt at this time, there is a risk that the bonding materials 23 and 34 will be expelled from the joint.

[0072] Considering these factors, the process temperature in each step is determined by the melting point of each bonding material, and it is preferable that the relationship of melting point of bonding material 71 < melting point of bonding material 41 ≦ melting point of bonding material 23 (bonding material 34) is satisfied. If a conductive adhesive or a sintered metal material is used for any of bonding materials 23, 34, 41, and 71, this relationship does not need to be satisfied. This is because the heat resistance temperature of the conductive adhesive or sintered metal material increases after the bonding process is completed, eliminating the concern of remelting in subsequent steps. In this embodiment, a sintered metal material (process temperature: 300°C) is used for bonding material 23, a high-temperature lead-free solder (process temperature: 250°C) is used for bonding material 34, a conductive adhesive (process temperature: 220°C) is used for bonding material 41, and a low-temperature lead-free solder (process temperature: 200°C) is used for bonding material 71.

[0073] (Effects of the power module 100) The power module 100 has a structure in which a printed circuit board 30 on which a drive circuit is mounted and an insulating substrate 10 (semi-completed module 60) on which semiconductor elements 20 driven by signals from the drive circuit are mounted are connected by a bonding material 41. When forming such a structure in the printed circuit board connection step S3, the through holes 38 and the positioning shapes 61 are used, so that the relative positions of the printed circuit board 30 and the semi-completed module 60 can be aligned with high precision.

[0074] More specifically, the amount of misalignment between the positioning shape 61 and the through-hole 38 at a predetermined temporary position is calculated, and the position of the printed circuit board 30 is fine-tuned by moving the transport arm 81 based on the amount of misalignment so that the X direction, Y direction, and θ direction (rotation direction within the XY plane) are positioned at the target relative position. By designing a digital camera (observation device 82) with an appropriate number of pixels and a transport arm 81 with repeatability, it is possible to reduce the amount of relative misalignment between the semi-completed module 60 and the printed circuit board 30 to, for example, 0.01 mm or less. If such high-precision alignment is possible, it will be possible to eliminate the possibility of the semi-completed module 60 and the printed circuit board 30 not being able to be joined due to misalignment during transport.

[0075] If the positioning shape 61 is a single straight line or multiple lines extending in one direction that is longer than the diameter of the through hole 38, it is not possible to detect misalignment in that direction with a single through hole 38. Also, if the positioning shape 61 is a circular point shape, it may be possible to position in the X and Y directions, but it is not possible to detect rotation in the θ direction. In the power module 100, the positioning shape 61 is two straight lines (first line 61a and second line 61b) that are oriented in different directions, and therefore positioning is possible with a single through hole 38. Therefore, when it is desired to miniaturize the printed circuit board 30, it is possible to minimize the area that cannot be used for component mounting.

[0076] The through holes 38 are also effective in the sealing process S4. Without the through holes 38, the sealing material 50 on the underside of the printed circuit board 30 would flow in from the resin gate 84a side in the X direction or from the opposite side. However, because the underside of the printed circuit board 30 contains the joint with the semi-completed module 60 and the resin 40, the sealing material 50 is less likely to flow and fill the central portion 10a. In the power module 100, the conductor islands 12a and 12b are separated in the central portion 10a. However, the insulation between these conductors with different potentials is designed based on the assumption that the sealing material 50 will be filled in order to achieve compactness. Therefore, if the sealing material 50 is not filled in the central portion 10a, insulation defects may occur. In the power module 100, part of the sealing material 50 flows to the underside of the printed circuit board 30 through the through holes 38, making it easier to fill the central portion 10a with the sealing material 50, thereby reducing the possibility of insulation defects.

[0077] As described above, in the power module 100, the through holes 38 and the positioning shapes 61 improve the relative positional accuracy of the printed circuit board 30 and the semi-finished module 60, thereby reducing joint defects and improving long-term reliability through stable joints. Furthermore, filling the sealant 50 using the through holes 38 reduces insulation defects, which also improves long-term reliability.

[0078] (Modifications) Fig. 12A is an enlarged view of the vicinity of a positioning shape 61 as seen through a through hole 38 in a power module 100 according to Modification 1. Fig. 12B is an enlarged view of the vicinity of the positioning shape 61 as seen through a through hole 38 in a power module 100 according to Modification 2. Fig. 12C is an enlarged view of the vicinity of the positioning shape 61 as seen through a through hole 38 in a power module 100 according to Modification 3.

[0079] Fig. 12D is an enlarged view of the vicinity of the positioning shape 61 as seen through the through hole 38 in the power module 100 according to Modification 4. Fig. 12E is an enlarged view of the vicinity of the positioning shape 61 as seen through the through hole 38 in the power module 100 according to Modification 5. As shown in Figs. 12A to 12E, the shapes of the through hole 38 and the positioning shape 61 are not limited to the example shown in Fig. 3.

[0080] As shown in Figures 12A to 12C, the positioning shape 61 is not limited to having a first line 61a and a second line 61b. For example, the positioning shape 61 may be a portion of the conductor island 12a (12b) that has been partially removed in an elliptical shape (see Figure 12A) or a rectangular shape (see Figure 12B), or a portion that has been removed in a curved shape (see Figure 12C). As shown in Figures 12D and 12E, the through hole 38 is not limited to being circular. For example, the through hole 38 may be rectangular (see Figure 12D) or oval (see Figure 12E).

[0081] In the examples shown in Figures 12A to 12C, the positioning shape 61 is formed by partially removing the conductor portion 12. In the examples shown in Figures 12D and 12E, the positioning shape 61 is formed by a portion of the conductor portion 12. The shapes shown in Figures 12A to 12E may be combined, or shapes other than those shown in Figures 12A to 12E may have different lengths, angles, and directions. In the examples shown in Figures 12D and 12E, the shape of the through hole 38 in a plan view does not match when the printed circuit board 30 is rotated or not. Therefore, in this case, the orientation of the printed circuit board 30 can be defined based on the shape of the through hole 38. Therefore, simply by observing the through hole 38, the orientations of the alignment lines 38a and 38b can be aligned with the longitudinal and lateral directions of the printed circuit board 30, respectively.

[0082] Second Embodiment A power module according to a second embodiment will be described. The power module according to the second embodiment is designated as power module 100A. Here, differences from power module 100 will be mainly described, and overlapping descriptions will not be repeated.

[0083] Fig. 13 is a plan view of a semi-complete module 60 included in the power module 100A. Fig. 14 is a plan view of a printed circuit board 30 included in the power module 100A. Fig. 15 is an enlarged view of XV in Fig. 13 as viewed through a through hole 38A. Fig. 16 is an enlarged view of XVI in Fig. 13 as viewed through a through hole 38B. As shown in Figs. 13 to 16, in the power module 100A, the semi-complete module 60 has two positioning shapes 61, and the printed circuit board 30 has two through holes 38.

[0084] One of the two positioning shapes 61 is referred to as a positioning shape 61A, and the other of the two positioning shapes 61 is referred to as a positioning shape 61B. One of the two through holes 38 for observing the positioning shape 61A is referred to as a through hole 38A, and the other of the two through holes 38 for observing the positioning shape 61B is referred to as a through hole 38B.

[0085] The positioning shapes 61A and 61B are located in the end regions 10b and 10c, respectively. More specifically, the positioning shape 61A is a side of the outline of the upper arm semiconductor (semiconductor element 20A) parallel to the Y direction that is closest to the outer edge of the insulating substrate 10. The positioning shape 61B is a side of the outline of the upper arm semiconductor (semiconductor element 20D) parallel to the X direction that is closest to the outer edge of the insulating substrate 10. The X and Y directions of the outlines of the positioning shapes 61A and 61B may be reversed. An outline other than the outline of the semiconductor element 20 may be visible through the through hole 38A (through hole 38B). The outlines of the upper arm semiconductor element and the lower arm semiconductor element arranged in parallel in the Y direction, other than those shown in the figure, may be used as the positioning shape 61. However, in the power module 100A, at least a portion of the semiconductor element 20 is visible through the through hole 38A and the through hole 38B.

[0086] 17 is an explanatory diagram of the printed circuit board connection step S3 in the manufacturing method of the power module 100A. As shown in FIG. 17, in the manufacturing method of the power module 100A, the number of observation devices 82 is two (these are referred to as observation devices 82A and 82B, respectively). However, the number of observation devices 82 may be one, and after observation of one through hole 38 is completed, the observation device 82 may be moved to observe another through hole 38.

[0087] The manufacturing method of the power module 100A differs in the observation of the positioning feature 61 in the printed circuit board connection step S3. FIG. 18A is a first example of an image captured by the observer 82A in the manufacturing method of the power module 100A. FIG. 18B is a first example of an image captured by the observer 82B in the manufacturing method of the power module 100A. FIG. 18C is a second example of an image captured by the observer 82A in the manufacturing method of the power module 100A. FIG. 18D is a second example of an image captured by the observer 82B in the manufacturing method of the power module 100A. As shown in FIGS. 18A to 18D, a straight line extending in the X direction (positioning feature 61B) or a straight line extending in the Y direction (positioning feature 61A) from one through-hole 38 can be observed from the observer 82A and the observer 82B.

[0088] The positioning shapes 61A and 61B look different when there is a misalignment in the X direction (see FIG. 18A ), when there is a misalignment in the Y direction (see FIG. 18B ), or when there is a misalignment in the θ direction (see FIGS. 18C and 18D ) between the semi-finished module 60 and the printed circuit board 30. In the manufacturing method of the power module 100A, fine adjustment of the position of the printed circuit board 30 is performed based on this difference in appearance.

[0089] The manufacturing method of the power module 100A differs with respect to the sealing step S4. FIG. 19 is an explanatory diagram of the sealing step S4 in the manufacturing method of the power module 100A. In FIG. 19, the resin flow of the sealing material 50 is indicated by arrows. As shown in FIG. 19, in the sealing step S4 in the manufacturing method of the power module 100A, in addition to the end portion on the resin gate 84a side and the opposite side, there are paths through which the sealing material 50 flows from the upper surface side to the lower surface side of the printed circuit board 30 in the through holes 38A on the end region 10b and the through holes 38B on the end region 10c. Furthermore, the semiconductor elements 20 are disposed directly below the through holes 38A and 38B.

[0090] The power module 100A has two through holes 38, and the positioning shapes 61A and 61B are straight lines extending in different directions. Therefore, even if these straight lines are long, misalignment in the X, Y, and θ directions can be finely adjusted by aligning the positioning shapes 61A and 61B with the positioning lines of the through holes 38A and 38B. The power module 100A makes it easy to use boundary lines and outlines in various locations as the positioning shapes 61 without having to create separate positioning shapes 61. Furthermore, because the power module 100A can use even long straight lines as the positioning shapes 61, it is also easy to use various boundary lines and outlines as positioning shapes. In this way, the power module 100A has a high degree of freedom in the positioning shapes 61 and the through holes 38 while achieving the same effects as the power module 100.

[0091] In the power module 100A, the through holes 38A and 38B are located on the end regions 10b and 10c, respectively, so the printed circuit board 30 is aligned at positions relatively far apart in the X direction. Therefore, just as the inclination of a straight line is closer to the ideal when a straight line is drawn by drawing a line passing through two distant points than when a line is drawn through two closely spaced points, the inclination error during alignment of the printed circuit board 30 can be reduced, thereby improving the relative positional accuracy of the semi-completed module 60 and the printed circuit board 30. Note that the number of through holes 38 and positioning shapes 61 in the power module 100A may be increased to three or more. In this case, more accurate positioning can be achieved by performing positioning at multiple locations, including locations where the relative positions of the semi-completed module 60 and the printed circuit board 30 must be reliably determined.

[0092] In the power module 100, if size expansion is permitted, insulation can also be achieved by increasing the distance between conductors with different potentials. In the semiconductor element 20, a potential difference of several hundred volts occurs over a Z-direction distance of about 0.1 mm to improve electrical characteristics. Even though an insulating member such as resin 40 is interposed, the semiconductor element 20 is disposed close to a printed circuit board 30 having wiring with various potentials.

[0093] In the power module 100A, the through holes 38A and 38B enable the semiconductor elements 20 to be more reliably sealed with the sealing material 50. In the example described above, the through holes 38A and 38B are located on positions close to diagonal positions on the insulating substrate 10, but by providing a positioning shape 61 at the center of the semiconductor elements 20 arranged in parallel in the Y direction and arranging the through holes 38 above it, it becomes easier to seal both adjacent semiconductor elements 20 with the sealing material 50. In this way, with the power module 100A, it is possible to provide the positioning shape 61 and the through holes 38 at locations where sealing with the sealing material 50 is desired to be more reliably performed.

[0094] Third Embodiment A power module according to a third embodiment will be described. The power module according to the second embodiment is designated as power module 100B. Here, differences from power module 100A will be mainly described, and overlapping descriptions will not be repeated.

[0095] FIG. 20 is a plan view of the semi-completed module 60 included in the power module 100B. FIG. 21 is a plan view of the printed circuit board 30 included in the power module 100B. Furthermore, FIG. 22 is an enlarged view of XXII in FIG. 20 as viewed through the through hole 38A. FIG. 23 is an enlarged view of XXIII in FIG. 20 as viewed through the through hole 38B. As shown in FIGS. 20 to 23, the positioning features 61A and 61B are round dots engraved by laser marking on the surface of the conductor portion 12. The positioning feature 61A is disposed between the semiconductor element 20A and the nearby joint 12aa. The positioning feature 61B is disposed between the semiconductor element 20B and the nearby joint 12ba.

[0096] 24 is an explanatory diagram of the printed circuit board connecting step S3 in the manufacturing method of the power module 100B. As shown in Fig. 24, in the printed circuit board connecting step S3 in the manufacturing method of the power module 100B as well, the positioning shape 61A and the positioning shape 61B are observed as a single round dot by the observation device 82A and the observation device 82B through the through hole 38A and the through hole 38B, respectively.

[0097] Fig. 25A is a first example of an image captured by the imaging device 62A in the manufacturing method of the power module 100B. Fig. 25B is a first example of an image captured by the imaging device 62B in the manufacturing method of the power module 100B. As shown in Figs. 25A and 25B, when there is a positional misalignment between the printed circuit board 30 and the semi-finished module 60 in the X direction (see Fig. 25A) or the Y direction (see Fig. 25B), the position of the printed circuit board 30 is fine-tuned using the positioning shapes 61A and 61B.

[0098] FIG. 25C is a second example of an image captured by the imaging device 62B in the manufacturing method of the power module 100B. As shown in FIG. 25C, even if the positioning feature 61A is aligned in the X and Y directions, there may be misalignment in the θ direction. In this case, the positioning feature 61B can be used to detect and adjust the misalignment (rotational misalignment) of the printed circuit board 30 in the θ direction. FIG. 26 is an explanatory diagram of the sealing step S4 in the manufacturing method of the power module 100B. As shown in FIG. 26, the sealing step S4 in the manufacturing method of the power module 100B differs from the sealing step S4 in the manufacturing method of the power module 100A in that there are paths through which the sealant 50 flows from the upper surface to the lower surface of the printed circuit board 30 through the through hole 38A located above the joint 12aa and the through hole 38B located above the joint 12ba.

[0099] In the power module 100B, similarly to the power module 100A, it is possible to improve the relative positional accuracy between the semi-completed module 60 and the printed circuit board 30.

[0100] The distance between the joint 12aa (joint 12ba) and the semiconductor element 20A (semiconductor element 20D) is a design factor, but it is preferable to make it short from the perspective of miniaturization. Furthermore, forming a notch in the conductor 12 and using the boundary between the notch and the insulating portion 11 as the positioning shape 61 reduces the cross-sectional area of ​​the current path, which is disadvantageous in terms of heat generation and heat dissipation, because the conductor 12 is the main current path between the joint 12aa (joint 12ba) and the semiconductor element 20A (semiconductor element 20D).

[0101] In the power module 100B, the markings made by laser marking are used as the positioning shapes 61, so it is possible to provide the positioning shapes 61 without reducing the current path area of ​​the conductor portion 12. Furthermore, since the positioning shapes 61 are formed by laser marking, they can be formed in an instant by laser irradiation. Furthermore, because the positioning shapes 61 are round dots, it is possible to observe the positioning shapes 61 even if the diameter of the through-holes 38 is reduced.

[0102] The potential near the joint 12aa is a P potential, and the potential near the joint 12ba is an AC potential. On the other hand, the potentials of the electrode surface of the semiconductor element 20A, the electrode surface of the printed circuit board 30 connected to the electrode surface of the semiconductor element 20A, and the wiring pattern of the printed circuit board 30 connected thereto are an AC potential or the potential of the drive signal. The potentials of the electrode surface of the semiconductor element 20D, the electrode surface of the printed circuit board 30 connected to the electrode surface of the semiconductor element 20D, and the wiring pattern of the printed circuit board 30 connected thereto are an N potential or the potential of the drive signal. In the power module 100B, the through holes 38A and 38B are respectively disposed above the location between the joint 12aa and the semiconductor element 20A and above the location between the joint 12ba and the semiconductor element 20B, so that the different potentials described above can be more reliably sealed and insulated with the sealing material 50.

[0103] In the sealing step S4 in the manufacturing method of the power module 100 and the power module 100A, the main direction of resin flow of the sealing material 50 is the X direction. Therefore, the semiconductor element 20A (semiconductor element 20D) and the resin 40 and bonding material 41 thereon act as a wall against the resin flow between the joint 12aa and the semiconductor element 20A (between the joint 12ba and the semiconductor element 20D), making it difficult for the sealing material 50 to fill the space between the joint 12aa and the semiconductor element 20A (between the joint 12ba and the semiconductor element 20D). In the power module 100B, a flow path for resin flow in the Y direction can be provided through the through hole 38A (through hole 38B) toward the space between the joint 12aa and the semiconductor element 20A (between the joint 12ba and the semiconductor element 20D). This allows the sealing material 50 to reliably seal the narrow portion between the joint 12aa and the semiconductor element 20A (between the joint 12ba and the semiconductor element 20D).

[0104] The embodiments disclosed herein should be considered to be illustrative in all respects and not restrictive. The scope of this application is defined by the claims, not the above description, and is intended to include all modifications within the meaning and scope of the claims.

[0105] 10 insulating substrate, 10a central portion, 10b edge region, 10c edge region, 11 insulating portion, 12 conductor portion, 12a, 12b, 12c conductor island, 12aa, 12ba, 12ca joint portion, 13 conductor portion, 20, 20A, 20B, 20C, 20D semiconductor element, 21, 22 electrode, 23 joint material, 30 printed circuit board, 31 electrode, 31a, 31b, 31c, 31d electrode, 32 driving IC, 33 electronic component, 34 joint material, 36a, 36b, 36c wiring pattern, 37a, 37c input terminal, 37b output terminal, 37d signal terminal, 38 through hole, 38A, 38B through hole, 38a, 38b alignment line, 40 resin, 41 joint material, 50 Sealant, 60 Semi-completed module, 61 Positioning shape, 61A, 61B Positioning shape, 61a First wire, 61b Second wire, 62A, 62B Imaging device, 70 Cooler, 71 Bonding material, 80 Fixing jig, 80a Groove, 80b Position restriction mechanism, 81 Transfer arm, 82 Observation device, 82A Observation device, 82B Observation device, 83 Controller, 84 Mold, 84a Resin gate, 100, 100A, 100B Power module, 200 Power conversion device, 210 Inverter circuit, 210a, 210b Terminal, 211, 212 Semiconductor element, 220 On-board battery, 230 Input capacitor, 240 Rotating electric machine, 250 Drive circuit, 260 Control circuit, 270 Power supply circuit, IC power supply, S1 Semiconductor element connection process, S2 Circuit component connection process, S3 Printed circuit board connection process, S4 sealing process, S5 cooler connection process.

Claims

1. A power module comprising: a semi-complete module; a printed circuit board; and a bonding material, wherein the semi-complete module has an insulating substrate and a semiconductor element, the insulating substrate has an insulating portion and a conductor portion arranged on an upper surface of the insulating portion, the semiconductor element is arranged on the conductor portion, the printed circuit board is arranged on top of the semi-complete module, a through hole is formed in the printed circuit board, and a positioning shape is formed in the insulating substrate at a position that can be observed through the through hole when viewed from the top side of the printed circuit board, and the semi-complete module and the printed circuit board are connected with the bonding material.

2. The power module according to claim 1, wherein the semiconductor element has a first electrode on an upper surface of the semiconductor element, the printed circuit board has a second electrode on a lower surface of the printed circuit board, and the second electrode is joined to the first electrode or the conductor portion by the joining material.

3. The power module according to claim 2, wherein the printed circuit board has at least a drive circuit on an upper surface thereof that generates a drive signal for the semiconductor element, the first electrode has a first main electrode and a first signal electrode, the second electrode has a second main electrode and a second signal electrode, the second main electrode is joined to the first main electrode or the conductor portion with the joining material, the second signal electrode is joined to the first signal electrode with the joining material, a main circuit current flows through the first main electrode and the second main electrode, a drive signal for the semiconductor element flows through the first signal electrode and the second signal electrode, and the second signal electrode is connected to the drive circuit by a wiring pattern in the printed circuit board.

4. A power module according to any one of claims 1 to 3, further comprising a sealing material, the sealing material filling part or all of the gap between the semi-complete module and the printed circuit board.

5. A power module according to any one of claims 1 to 4, wherein the number of the through holes is one, and the positioning shape is a first line and a second line extending in a direction different from that of the first line.

6. A power module according to any one of claims 1 to 4, wherein the through holes include a first through hole and a second through hole, and the positioning features include a first positioning feature located in a position observable through the first through hole, and a second positioning feature located in a position observable through the second through hole.

7. The power module according to claim 6, wherein the first positioning feature is a first line, and the second positioning feature is a second line extending in a different direction from the first line.

8. The power module of claim 6, wherein the first positioning feature and the second positioning feature are points.

9. The power module according to claim 4, wherein the through hole is located at the center in the longitudinal direction of the semi-complete module when viewed from the top surface side of the printed circuit board.

10. The power module according to claim 4, wherein the insulating substrate has, in the longitudinal direction of the insulating substrate, a first end face and a second end face that is the opposite surface to the first end face, the insulating substrate has, in the longitudinal direction of the insulating substrate, a central portion, a first end region that is closer to the first end face than the central portion, and a second end region that is closer to the second end face than the central portion, the through holes have first through holes and second through holes, and when viewed from the top side of the printed circuit board, the first through holes and the second through holes are arranged in positions that allow the first end region and the second end region to be seen, respectively.

11. A power module as described in claim 4, wherein the conductor portion has a first conductor portion island and a second conductor portion island, the first conductor portion island has a different potential from the second conductor portion island, and when viewed from the top surface of the printed circuit board, the through hole is positioned so that the insulating portion between the first conductor portion island and the second conductor portion island can be seen.

12. The power module according to claim 4, wherein the through-hole is arranged at a position where a part of the semiconductor element is visible when viewed from above the printed circuit board.

13. A method for manufacturing a power module, comprising the steps of: preparing a semi-completed module and a printed circuit board; the semi-completed module having an insulating substrate and a semiconductor element; the insulating substrate having an insulating portion and a conductor portion disposed on an upper surface of the insulating portion; the semiconductor element being disposed on the conductor portion; the semi-completed module having a positioning shape; the printed circuit board being disposed on top of the semi-completed module; and a through hole being formed in the printed circuit board; transporting the printed circuit board to a temporary position above the semi-completed module; observing the positioning shape through the through hole using an observation device and determining the amount of misalignment between the semi-completed module and the printed circuit board; adjusting the position of the printed circuit board based on the amount of misalignment; and joining the semi-completed module and the printed circuit board.

14. The method for manufacturing a power module according to claim 13, further comprising the step of sealing the semi-completed module and the printed circuit board with a sealing material after the step of joining the semi-completed module and the printed circuit board.

Images