Semiconductor module, power conversion device, and manufacturing method of semiconductor module

A semiconductor module includes a semiconductor device that includes first and second fin bases having first and second connecting portions and a resin for sealing the outer peripheral side surfaces of first to fourth conductors, and a flow path forming body connected to the first and second connecting portions of the first and second fin bases. A first elastically deformed portion, which is elastically deformed, is provided such that a distance in a thickness direction between the outer peripheral ends of the first and second connecting portions becomes smaller than a distance in a thickness direction between intermediate portions of the first and second connecting portions. The resin is filled between the first and second connecting portions of the first and second fin bases are filled with the resin therebetween.

TECHNICAL FIELD

The present invention relates to a semiconductor module, a power conversion device, and a manufacturing method of the semiconductor module.

BACKGROUND ART

A semiconductor module containing a power semiconductor element that performs a switching operation has high conversion efficiency, and is widely used for consumer use, in-vehicle use, railway use, substation equipment, and the like. Since the power semiconductor element generates heat when energized, high heat dissipation is required for the semiconductor module. In particular, for in-vehicle applications, a highly efficient cooling system using a liquid refrigerant such as water for cooling the semiconductor module is adopted in order to reduce the size and weight.

An example of the structure and manufacturing method of such a semiconductor module is illustrated below.

A pair of upper and lower cases that sandwich the power module having a power semiconductor element therebetween and have a U-shaped cross section in which the peripheral wall portions are bent substantially vertically are arranged so that the side end faces of the peripheral wall portions of each case face each other. The pair of upper and lower cases are pressurized from the outside, and the peripheral wall portions of the cases are deformed so that the distance between them becomes smaller so that the side end faces of the pair of upper and lower cases come into contact with each other. In this state, the contact portions on the side end faces are bonded by welding or the like. In such a process, the power module is fixed in the case. (See, for example, PTL 1).

CITATION LIST

Patent Literature

SUMMARY OF INVENTION

Technical Problem

The semiconductor module of PTL 1 requires a procedure of crimping the power module to the case and then a procedure of welding the bonding surface of the case, and the productivity is low. Further, PTL 1 does not describe a semiconductor module capable of cooling with a refrigerant.

Solution to Problem

A semiconductor module according to one aspect of the invention includes: a semiconductor device, which includes a semiconductor element, a pair of conductors that is arranged so as to sandwich the semiconductor element and face each other in a thickness direction, and connected to the semiconductor element, respectively, a first heat dissipation member that is arranged on a surface of a side opposite to the semiconductor element of one conductor of the pair of conductors via an insulating member, and includes a first connecting portion extending outward from an outer peripheral side surface of the one conductor, a second heat dissipation member that is arranged on a surface of a side opposite to the semiconductor element of the other conductor of the pair of conductors via an insulating member, and includes a second connecting portion extending outward from an outer peripheral side surface of the other conductor, and a resin for sealing the outer peripheral side surfaces of the pair of conductors; and a flow path forming body that is connected to the first connecting portion of the first heat dissipation member and the second connecting portion of the second heat dissipation member of the semiconductor device. A first elastically deformed portion which is elastically deformed is provided such that a distance in a thickness direction between an outer peripheral end of the first connecting portion of the first heat dissipation member and an outer peripheral end of the second connecting portion of the second heat dissipation member becomes smaller than a distance in a thickness direction between an intermediate portion of the first connecting portion of the first heat dissipation member and an intermediate portion of the second connecting portion of the second heat dissipation member. The resin is filled between first connecting portion of the first heat dissipation member and the second connecting portion of the second heat dissipation member.

Advantageous Effects of Invention

According to the invention, the productivity of a semiconductor module having a flow path forming body can be improved.

DESCRIPTION OF EMBODIMENTS

First Embodiment

Hereinafter, embodiments of the invention will be described with reference to the drawings. The following description and drawings are exemplifications for describing the invention, and are omitted and simplified as appropriate for clarification of the description. The invention can be implemented in other various forms. Unless otherwise limited, each component may be singular or plural.

The position, size, shape, range, and the like of each component illustrated in the drawings may not necessarily represent the actual position, size, shape, range, and the like, in order to facilitate understanding of the invention. For this reason, the invention is not necessarily limited to the position, size, shape, range, and the like disclosed in the drawings.

FIG.1is an external perspective view of an embodiment of a semiconductor device constituting the semiconductor module of the invention.

In the following description, the X direction, the Y direction, and the Z direction are as illustrated in the drawings.

FIG.1is an external perspective view of an embodiment of the semiconductor device according to the invention.

The semiconductor device300includes a device body301which is a resin package in which internal electronic components are sealed with a resin850, a fin base800, a plurality of power terminals for inputting/outputting a large current, and a plurality of signal terminals for inputting/outputting signals. The device body301has a substantially rectangular parallelepiped shape, in other words, a substantially rectangular shape when a main surface302having the largest area is in a plan view from the vertical direction. The plurality of power terminals and the plurality of signal terminals project from one side301ain the length direction (X direction) of the device body301and the other side301bfacing the one side. The fin base800having a large number of fins800ais provided on each of the main surface302of the device body301and a back surface303which is the facing surface of the main surface302. On the outer peripheral edge of each fin base800, the connecting portion810with a flow path forming body600(seeFIG.10) forming a space for arranging the refrigerant is provided.

Power terminals such as a positive electrode side terminal315B and a negative electrode side terminal319B project from the other side301bof the device body301. An AC side terminal320B projects as a power terminal from one side301aof the device body301.

Signal terminals such as a lower-arm gate signal terminal325L, a mirror emitter signal terminal325M, a Kelvin emitter signal terminal325K, and a collector sense signal terminal325C project from the other side301bof the device body301. Signal terminals such as an upper-arm gate signal terminal325U, a temperature sense signal terminal325S, the mirror emitter signal terminal325M, the Kelvin emitter signal terminal325K, and the collector sense signal terminal325C project from one side301aof the device body301. When these signal terminals are comprehensively described, a signal terminal325is used.

As illustrated inFIG.1, the positive electrode side terminal315B and the negative electrode side terminal319B, which are power terminals, and the AC side terminal320B are provided so as to face each other on the other side301band one side301aof the device body301.

The plurality of power terminals and the plurality of signal terminals project in the longitudinal direction (+X direction and −X direction), and the tip is vertically bent and extended in the height direction (+Z direction). By directing the plurality of signal terminals in the same +Z direction, it becomes easy to connect to the control circuit and driver circuit. Further, since the control terminal is divided into two sides, one side301aand the other side301bof the device body301and projects, the creepage distance and the space distance between the terminals are secured.

The positive electrode side terminal315B and the negative electrode side terminal319B are arranged adjacent to each other on the other side301bside of the device body301in the Y direction. Further, the positive electrode side terminal315B and the negative electrode side terminal319B are arranged so that the side surfaces, which are small areas refracted in an L shape, face each other, so that the input/output currents are brought close to each other to reduce the inductance. In addition, since the positive electrode side terminal315B and the negative electrode side terminal319B, which are DC terminals, are connected to the capacitor module500(seeFIG.12) connected to a battery, the terminals project from the same other side301bside, so that the effect of simplifying the inverter layout is obtained. The AC side terminal320B protrudes from the facing surface opposite to the surface on which the DC-side terminal protrudes. After connecting to a current sensor180(seeFIG.12), the AC side terminal320B protrudes from the power conversion device and is connected to motor generators192and194(seeFIG.12). Therefore, there is an effect that the inverter layout can be simplified by projecting in a direction different from the DC terminal connected to the capacitor module500.

FIG.2(a)is a cross-sectional view taken along line II-II of the semiconductor device illustrated inFIG.1,FIG.2(b)is an enlarged view of the connecting portion810illustrated inFIG.2(a), andFIG.3is a circuit diagram illustrating an example of the circuit of the semiconductor device illustrated inFIG.1.

The semiconductor device300includes an upper arm circuit having a switching function including an active element155and a diode156, and a lower arm circuit having a switching function including an active element157and a diode158. The active elements155and157and the diodes156and158are called semiconductor elements. This semiconductor element is not particularly limited as long as it has a switching function, but transistors such as IGBT (Insulated Gate Bipolar Transistor) and MOSFET (Metal-Oxide-Semiconductor Field-Effect Transistor) are used as the active elements155and157. As the diodes156and158, SBD (Schottky Diode), FRD (Fast Recovery Diode) and the like are used. Si is often used as a material for constituting the semiconductor element, but SiC, GaN, GaO, or the like can also be used.

As illustrated inFIG.3, the positive electrode side terminal315B is connected to a third conductor412. The collector electrode of the active element155and the cathode electrode of the diode156constituting the switching element of the upper arm circuit are electrically connected by the third conductor412. The emitter electrode of the active element155and the anode electrode of the diode156are electrically connected by the second conductor411.

The negative electrode side terminal319B is electrically connected to a fourth conductor413. The emitter electrode of the active element157and the anode electrode of the diode158constituting the switching element of the lower arm circuit are electrically connected by the fourth conductor413. The collector electrode of the active element157and the cathode electrode of the diode158are electrically connected by a first conductor410. The first conductor410and the second conductor411are electrically connected via an intermediate electrode portion414. The AC side terminal320B is electrically connected to the first conductor410. The Kelvin emitter signal terminal325K is connected to the emitter electrode of each of the upper arm circuit and the lower arm circuit. The collector sense signal terminal325C of the upper arm circuit is electrically connected to the third conductor412, and the collector sense signal terminal325C of the lower arm circuit is connected to the first conductor410.

The active elements155and157may be configured to include a plurality of active elements155and157, respectively.

As illustrated inFIG.2(a), the collector electrode of the active element155and the anode electrode of the diode156are bonded to the third conductor412via a metal bonding member51such as solder or sintered metal. The emitter electrode of the active element155and the cathode electrode of the diode156are bonded to the second conductor411via the metal bonding member51such as solder or sintered metal. The collector electrode of the active element157and the diode158(anode electrode (not illustrated inFIG.2)) are bonded to the first conductor410via the metal bonding member51such as solder or sintered metal. The emitter electrode of the active element157(not illustrated inFIG.2) and the cathode electrode of the diode158are bonded to the fourth conductor413by the metal bonding member51such as solder or sintered metal. The first conductor410is bonded to the intermediate electrode portion414(see alsoFIG.6(a)) integrally formed with the second conductor411by the metal bonding member51. As a result, the first conductor410and the second conductor411are electrically connected.

The entire lower surface of the active elements155and157is a collector electrode, the entire lower surface of the diodes156and158is an anode electrode, and the active area of the upper surface is a cathode electrode.

The first to fourth conductors410to413are formed of copper or aluminum, but other materials may be used as long as they are materials having a high electrical conductivity. A collector-side wiring board423is arranged on the lower surface (+Z direction) of the first conductor410and the third conductor412. The collector-side wiring board423is bonded to the first conductor410and the third conductor412by a metal bonding member51such as solder or sintered metal. The collector-side wiring board423is configured by forming a wiring452made of copper or aluminum on the front and back surfaces of an insulating plate451made of ceramic or the like. The first conductor410and the third conductor412are bonded to the wiring452by the metal bonding member51. The conductors and wirings to be metal-bonded may be plated or provided with fine irregularities in order to increase the bonding strength. The electrodes of the active elements155and157each are connected to the wiring formed on the collector-side wiring board423by a wire840, and are connected to the signal terminal325exposed to the outside of the resin850by a wire841. The wires840and841may be formed of continuous wires depending on the connection layout. The connection between the electrodes of the active elements155and157and the wiring will be described later.

An emitter-side wiring board422is arranged on a surface of the upper side (−Z direction) of the second conductor411and the fourth conductor413. The emitter-side wiring board422is bonded to the second conductor411and the fourth conductor413by a metal bonding member51such as solder or sintered metal. The emitter-side wiring board422is configured by forming a wiring454made of copper or aluminum on the front and back surfaces of an insulating plate453made of ceramic or the like. The second conductor411and the fourth conductor413are bonded to the wiring454formed on the emitter-side wiring board422by the metal bonding member51.

InFIG.2(a), the fin bases800are bonded to the lower surface of the collector-side wiring board423and the upper surface of the emitter-side wiring board422, respectively. The collector-side wiring board423or the emitter-side wiring board422and the fin base800are bonded by a metal bonding member51such as solder or sintered metal.

The upper and lower fin bases800are sealed with the resin850. The resin850is formed by, for example, molding such as a transfer mold.

The fin base800having a large number of fins800ais a heat dissipation member, and has the connecting portion810extending outward from an outer peripheral end422aof the emitter-side wiring board422or an outer peripheral end423aof the collector-side wiring board423. The connecting portion810has low rigidity formed to a thickness substantially equal to or thinner than the thickness (length in the Z direction) from the bottom surface of the fin base800to the base of the fin800a.

As illustrated inFIG.2(b), the connecting portion810has a flat intermediate portion804approximately parallel to the XY plane. Further, the connecting portion810has first to third elastically deformed portions801to803. The first elastically deformed portion801is formed on an outer peripheral end810aside of the connecting portion810. The second elastically deformed portion802is formed in a region corresponding to the outer peripheral end422aof the emitter-side wiring board422or the outer peripheral end423aof the collector-side wiring board423, which is the root side of the connecting portion810. The third elastically deformed portion803is formed on the side opposite to the first elastically deformed portion801side in the intermediate portion804. The distance in the thickness direction (Z direction) between the outer peripheral ends810aof the upper and lower fin bases800is smaller than the distance in the thickness direction (Z direction) between the intermediate portions804of the upper and lower fin bases800.

The resin850that covers the outer peripheral side surfaces of the first to fourth conductors410to413is filled between the connecting portions810of the upper and lower fin bases800. The first to third elastically deformed portions801to803of the connecting portion810are formed at the time of the molding when a pre-sealing semiconductor device configuration304(seeFIG.5(a)) is installed in a mold852(seeFIG.8(a)), and a resin material850S (seeFIG.8(a)) is injected into the mold852. This has the effect of reducing the variation in the spacing between the intermediate portions804of the connecting portions810in the upper and lower fin bases800. This will be described later.

The shape of the connecting portion810protruding from the left and right of the fin base800inFIG.2(b)is the shape after being sealed with resin. The connecting portion810of the fin base800before resin sealing has the shape of a thin flat plate extending in the X direction. Then, as will be described later, when loaded into the mold for molding, as illustrated inFIGS.8(a) and8(b), the connecting portion810of the pair of upper and lower fin bases800is pressed between the upper and lower molds852aand852band elastically deformed, and becomes the shape illustrated inFIG.2(b)in the molding process for filling resin.

FIGS.4(a) to4(c)are cross-sectional views in each step for explaining the manufacturing method of the semiconductor device illustrated inFIG.1, andFIGS.5(a)to5(b) are cross-sectional views in each process for explaining the manufacturing method of the semiconductor device subsequent toFIGS.4(a)to4(c).FIGS.6(a) to6(c)are perspective views of the processes corresponding toFIGS.4(a)to4(c), respectively, andFIGS.7(a) to7(b)illustrate perspective views of the processes corresponding toFIGS.5(a)to5(b), respectively.

With reference toFIGS.4(a) to4(c),5(a) to5(b),6(a) to6(c) and7(a)to7(b), the manufacturing method of the semiconductor device300illustrated inFIG.1will be described.

As illustrated inFIGS.4(a) and6(a), the collector electrode of the active element155and the cathode electrode of the diode156are bonded to the third conductor412by the metal bonding member51. Similarly, the collector electrode of the active element157and the cathode electrode of the diode158are bonded to the first conductor410by the metal bonding member51.

Further, the emitter electrode of the active element155and the anode electrode of the diode156are bonded to the second conductor411by the metal bonding member51. Similarly, the emitter electrode of the active element157and the anode electrode of the diode158are bonded to the fourth conductor413by the metal bonding member51.

InFIGS.4(a) to4(c),5(a), and5(b), the AC side terminal320B is integrally formed in the first conductor410in order to increase productivity, but the AC side terminal320B may be formed separately from the first conductor410.

Next, as illustrated inFIGS.4(b) and6(b), the collector side wiring board423is bonded to the lower surfaces of the first conductor410and the third conductor412by the metal bonding member51, and the electrodes of the active elements155and157each are electrically connected to the wiring452of the collector-side wiring board423by the wire840. Further, each wiring452and all the signal terminals illustrated inFIG.1are connected by the wire841.

Subsequent processes are illustrated inFIGS.4(c) and6(c). As illustrated in these drawings, the wiring454on the lower side (Z direction side) of the emitter-side wiring board422is bonded to the upper surfaces of the second conductor411and the fourth conductor413by the metal bonding member51.

In this embodiment, the first conductor410and the third conductor412, which are collector-side conductors, and the collector-side wiring board423are separated from each other. Although the thickness of the wiring452of the collector-side wiring board423is thin, the thickness of the first conductor410and the third conductor412is thick, so that heat can be diffused in the plane direction. By reducing the thickness of the wiring452of the collector-side wiring board423, the collector-side wiring board423can be made cheaper, and since the thickness of the wiring452is thin, the wiring pattern can be miniaturized, and the area of the collector-side wiring board423is reduced, and miniaturization becomes possible.

The same applies to the emitter side, and the second conductor411and the fourth conductor413, which are the emitter-side conductors, and the emitter-side wiring board422are separated from each other, whereby heat can be diffused through the second conductor411and the fourth conductor413in the plane direction, and the emitter-side wiring board422can be made inexpensive and miniaturized.

The fin bases800are provided on the front and back surfaces of the intermediate obtained in the process ofFIG.4(c). That is, as illustrated inFIGS.5(a) and7(a), the fin base800is bonded to the lower surface of the collector-side wiring board423and the upper surface of the emitter-side wiring board422by the metal bonding member51, respectively. The fin base800is made of, for example, aluminum. When the wiring452of the collector-side wiring board423and the wiring454of the emitter-side wiring board422are formed of copper, the fin base800is warped due to the difference in thermal expansion between aluminum and copper. However, in this embodiment, the fin base800is bonded by the metal bonding member51to each of the collector-side wiring board423bonded to the first conductor410and the third conductor412, and the emitter-side wiring board422bonded to the second conductor411and the fourth conductor413, respectively. Therefore, it is possible to reduce the warp when bonding the fin base800. Therefore, the bonding process of the fin base800can be a low pressure or no pressure bonding process instead of the pressure bonding process. As a result, the cost of the production equipment can be reduced.

The bonding surface of the fin base800may be nickel-plated.

Further, the collector-side wiring board423and the emitter-side wiring board422may be bonded to the fin base800in advance by a metal bonding member51or the like.

The semiconductor device300before being sealed with the resin850illustrated inFIGS.5(a) and7(a)is referred to as a pre-sealing semiconductor device configuration304.

The pre-sealing semiconductor device configuration304obtained in the process ofFIGS.5(a) and7(a)is resin-sealed. That is, as illustrated inFIGS.5(b) and7(b), the pre-sealing semiconductor device configuration304provided between the pair of upper and lower fin bases800is sealed with the resin850. Sealing with the resin850is performed by transfer mold molding. Before the resin molding, the pre-sealing semiconductor device configuration304may be coated with a resin thin film.

FIG.8(a)is a cross-sectional view of the process of installing the pre-sealing semiconductor device configuration in a mold and performing resin molding, andFIG.8(b)is an enlarged view of a region VIIIb ofFIG.8(a), andFIG.8(c)is a side view illustrating the shape of the connecting portion810of the fin base800before the pre-sealing semiconductor device configuration is resin-molded.

With reference toFIG.8(c), the connecting portion810of the fin base800before the resin molding has the shape of a thin flat plate extending parallel to the X direction. Then, referring toFIG.8(b), when the pre-sealing semiconductor device configuration is loaded in the mold for resin molding, the pair of upper and lower connecting portions810are pressed in the Z direction at stepped portions855of the upper and lower molds852aand852b, and deformed as illustrated inFIG.8(b). The details will be described below.

As illustrated inFIG.8(a), the pre-sealing semiconductor device configuration304illustrated inFIG.5(a)is installed in the cavity of the mold852composed of a lower mold852aand an upper mold852b. As described with reference toFIG.8(c), each fin base800is formed with a low-rigidity connecting portion810. When the pre-sealing semiconductor device configuration304is installed in the upper and lower molds852aand852b, the outer peripheral end810aof the connecting portion810abuts on a first surface857of the stepped portion855bof the upper mold852bas illustrated inFIG.8(b). Similarly, although not illustrated inFIG.8(b), the outer peripheral end810aabuts on the first surface857of the stepped portion855aof the lower mold852a. The reason for this is illustrated below.

FIG.19is a schematic view for explaining deformation of the connecting portion of the fin base by a mold in a state where the pre-sealing semiconductor device configuration is installed in the mold.FIG.19is also referred for description.

Reference numeral810-1illustrated by a solid line inFIG.19indicates the shape of the connecting portion810extending parallel to the X direction before deformation before the resin molding.

The lower mold852aand the upper mold852bare formed with a stepped portion855aor a stepped portion855b, respectively. The structure of the stepped portion855aof the lower mold852aand the stepped portion855bof the upper mold852bare the same, and the stepped portion855aand the stepped portion855bwill be described below as the stepped portion855as a representative. Further, the stepped portion855has the first surface857and a second surface858extending in the X direction and facing the −Z direction.

For the length in the X direction, the length between the outer peripheral ends810aof the connecting portion810, that is, the dimension X810illustrated inFIG.19, is larger than the length between the vertical side surfaces856of the stepped portion855, that is, the dimension X856illustrated inFIG.19. The distance in the thickness direction (Z direction) between the first surface857of the stepped portion855bof the upper mold852band the first surface857of the stepped portion855aof the lower mold852a, that is, the dimension Z857illustrated inFIG.19is set to be smaller than the distance between the connecting portions810of the upper and lower fin bases800of the pre-sealing semiconductor device configuration304in the thickness direction (Z direction), that is, the dimension Z810illustrated inFIG.19. Further, the distance between a second surface858of the stepped portion855bof the upper mold852band the second surface858of the stepped portion855aof the lower mold852ain the thickness direction (Z direction), that is, the dimension Z858illustrated inFIG.19is set to be larger than the distance Z810between the connecting portions810of the upper and lower fin bases800of the pre-sealing semiconductor device configuration304.

The first surface857and the second surface858of the stepped portions855aand855bof the mold852are formed on a flat surface substantially parallel to the XY surface.

As described above, the dimensions of the connecting portion810of the fin base800, and the first surface857and the second surface858of the mold stepped portions855aand855bare set as described above. Therefore, when the pre-sealing semiconductor device configuration304is installed in the cavity of the mold852and the mold852is closed, the portions near the outer peripheral ends810aof the connecting portions810of the upper and lower fin bases800each correspond to corners at which the first surface857of the stepped portion855bor the stepped portion855aand a vertical side surface856intersect as illustrated inFIGS.8(a) and8(b), and a connecting portion810-1before deformation indicated by a solid line inFIG.19is bent like a connecting portion810-2after deformation indicated by a two-dot chain line810-2.

FIG.9(a)is a diagram for explaining the action of the resin in a state where the resin is injected into the mold illustrated inFIG.8(a), andFIG.9(b)is an enlarged view of a region XIb ofFIG.9(a).

The resin material850S is injected into the mold852in the state illustrated inFIGS.8(a) and8(b). The resin material850S flows into the cavity of the mold852and is filled between the connecting portions810of the upper and lower fin bases800to seal the outer peripheral side surfaces of the first to fourth conductors410to413. As described above, in this state, the connecting portions810of the upper and lower fin bases800are pressed against the first surfaces857of the stepped portions855band855a, respectively. Therefore, the resin material850S injected between the upper and lower fin bases800is suppressed from leaking at the contact portion between the connecting portion810of the upper and lower fin bases800and the first surface857of the stepped portion855bor the stepped portion855a, and no leakage to the second surface858side of the step855bor step855aoccurs.

When the pre-sealing semiconductor device configuration304to which the pair of upper and lower fin bases800are bonded is strongly clamped by the mold852, excessive stress is generated in the active elements155and157and the like. However, since the fin base800is provided with the connecting portion810and the fin base800is configured to bend with a small load at the low-rigidity connecting portion810, the stress acting on the active elements155and157, etc. can be relaxed.

Further, as illustrated inFIG.8(a), a spring mechanism864is provided in the mold852. The spring mechanism864has a function of preventing peeling that acts on the active elements155and157, etc. via the first to fourth conductors410to413and the collector-side/emitter-side wiring boards422and423. Peeling is the following phenomenon. That is, a hydrostatic pressure Ps expanding the space between the fin bases800acts on the upper and lower fin bases800by the resin material850S that is filled around the pre-sealing semiconductor device configuration304installed in the cavity of the mold852(seeFIGS.9(a) and9(b)). Therefore, a peeling force acts on the active elements155and157, etc. via the first to fourth conductors410to413and the collector-side/emitter-side wiring boards423and422. By making the pressing force on the pre-sealing semiconductor device configuration304by the spring mechanism864larger than the pressing force on the pre-sealing semiconductor device configuration304generated by the mold clamping forces of the upper and lower molds852aand852b, the peeling force acting on the active elements155and157, etc. can be canceled.

The active elements155and157, etc. are strong against the pressing force, but weak against the peeling force, and cause breakage or failure. By making the pressing force on the pre-sealing semiconductor device configuration304by the spring mechanism864larger than the peeling force generated by the pressure of the resin material850S, it is possible to prevent that the active elements155and157, etc. during resin molding are destroyed or broken.

As illustrated inFIG.9(a), the resin material850S, which has fluidity before curing, flows into the pre-sealing semiconductor device configuration304installed in the cavity of the mold852, and thus the pressure applied to the resin material850S is loaded onto the mold852and the pre-sealing semiconductor device configuration304as the hydrostatic pressure Ps.

As illustrated inFIG.9(b), the hydrostatic pressure Ps generated by the resin material850S deforms the connecting portion810of the fin base800, and presses on the second surfaces858of the stepped portions855aand855bof the upper and lower molds852aand852b. At this time, the first elastically deformed portion801, the second elastically deformed portion802, the third elastically deformed portion803, and the flat intermediate portion804are formed on the connecting portion810.

As illustrated inFIG.9(b), the connecting portion810of the fin base800is deformed by the first elastically deformed portion801so that the outer peripheral end810ais located above the first surfaces857of the stepped portions855aand855b. The connecting portion810of the fin base800is also deformed by the second elastically deformed portion802and the third elastically deformed portion803, and the intermediate portion804is deformed so as to be flat according to the surface of the second surface858of the mold852. The connecting portion810of the fin base800is deformed by the second elastically deformed portion802on the root side so as to expand obliquely outward and toward the third elastically deformed portion803.

When the injection pressure of the resin material850S is 5 MPa, if the connecting portion810is made of an aluminum material of 0.6 mm or less, the connecting portion810having the first to third elastically deformed portions801to803and the intermediate portion804can be formed.

Normally, at a height position in the thickness direction of the connecting portion810of the upper and lower fin bases800of the pre-sealing semiconductor device configuration304, in other words, the Z direction (hereinafter, may be simply referred to as “height position”), a variation of about 0.1 mm occurs in one pre-sealing semiconductor device configuration304itself due to component tolerances and variations during assembly. Further, a variation of about 0.2 mm occurs in the plurality of pre-sealing semiconductor device configurations304.

On the other hand, in this embodiment, the intermediate portions804of the connecting portions810of the upper and lower fin bases800are pressed against the flat second surfaces858of the upper and lower molds852aand852bby the resin materials8508at the time of molding. The connecting portion810is formed by elastic deformation so as to maintain this state. That is, even if the height positions of the intermediate portions804of the connecting portions810of the upper and lower fin bases800of the pre-sealing semiconductor device configuration304vary, the height positions of the intermediate portions804of all the connecting portions810of the pre-sealing semiconductor device configuration304can be set to the position of the second surfaces858of the upper and lower molds852aand852b. Therefore, the variation in height position of the intermediate portions804of the connecting portions810of the upper and lower fin bases800of the semiconductor device300can be extremely reduced. In the study by the present inventor, the variation in height position of the intermediate portions804of the connecting portions810of the upper and lower fin bases800could be made about 0.01 mm even among the plurality of semiconductor devices300.

In the description of the elastic deformation of the connecting portion810of the fin base800, it has been described regarding the X direction. However, as it is clear fromFIG.10, the connecting portion810of the fin base800is elastically deformed even in the Y direction similarly to the X direction.

Although not illustrated, the packaging of the first to fourth conductors410to413, power terminals, and signal terminals is performed in a state where the first to fourth conductors410to413, the power terminals, and the signal terminals are connected by a tie bar until the resin molding. After the resin molding, the tie bar is cut, and the power terminal and the signal terminal are processed into a predetermined shape, whereby the semiconductor device300illustrated inFIG.1can be obtained.

FIG.10is a cross-sectional view illustrating an example of the first embodiment of the semiconductor module according to the invention.

A semiconductor module900includes the semiconductor device300and the flow path forming body600.

As described above, in the semiconductor device300, the fin bases800are arranged above and below the first to fourth conductors410to413, and the first to fourth conductors410to413are sealed by the resin850filled between the connecting portions810of the fin base800. The connecting portion810has the intermediate portion804exposed on the upper and lower surfaces (Z direction) of the resin850.

The flow path forming body600has an upper case601aand a lower case601b. The upper case601ais bonded to the upper (−Z direction) fin base800, and the lower case601bis bonded to the lower (Z direction) fin base800. The bonding structure between the upper case601aand the fin base800and the bonding structure between the lower case601band the fin base800are the same. In the following, the upper case601aand the lower case601bare represented by the case601and the bonding structure between the case601and the fin base800will be described.

The case601has a base portion602having a rectangular frame shape in a plan view, and a cover portion603integrally formed with the base portion602. The base portion602is formed in a flat shape substantially parallel to the XY plane, and is bonded to the intermediate portion804of the connecting portion810of the fin base800. The cover portion603rises up from the base portion602to a height at which a gap is formed between the base portion602and the tip of the fin800aof the fin base800. The gap between the cover portion603and the fin800aof the fin base800constitutes a cooling flow path Cw through which a refrigerant such as water flows.

The cooling flow path Cw between the upper case601aand the lower case601bis provided with a refrigerant inlet13(seeFIG.16) and a refrigerant outlet14(seeFIG.16) communicating with each other in a region (not illustrated). The case601aand the lower case601bare assembled to form the flow path forming body600.

The base portion602of the case601and the intermediate portion804of the connecting portion810of the fin base800are bonded by a bonding portion650. The bonding portion650is formed over the entire circumference on the resin850that seals the outer peripheral side surfaces of the first to fourth conductors410to413.

Adhesion or welding using resin can be used for bonding the base portion602of the case601and the connecting portion810of the fin base800, but welding having excellent durability is preferable. Laser welding can be used as the bonding by welding. Generally, in laser welding, if a gap of 0.1 mm or more is generated between the members to be bonded, the risk of welding defects increases. As described above, in this embodiment, the variation in height position of the intermediate portions804of the connecting portions810of the upper and lower fin bases800could be made about 0.01 mm even among the plurality of semiconductor devices300. Therefore, the reliability and workability of the bonding between the flow path forming body600and the fin base800can be improved, and thus the productivity can be improved.

FIG.11is a cross-sectional view illustrating another example of the first embodiment of the semiconductor module according to the invention.

A semiconductor module900A illustrated inFIG.11has two semiconductor devices300and one flow path forming body600A. The flow path forming body600A has an upper case601cand a lower case601d. The upper case601cis bonded to the upper (−Z direction) fin base800, and the lower case601dis bonded to the lower (Z direction) fin base800. The bonding structure between the upper case601cand the fin base800and the bonding structure between the lower case601dand the fin base800are the same. In the following, the upper case601cand the lower case601dare represented by the case601and the bonding structure between the case601and the fin base800will be described.

The case601has a frame-like shape, is arranged between the two semiconductor devices300, and is bonded to both of the semiconductor devices300. That is, the case601is bonded to the connecting portion810of the fin base800of one semiconductor device300at the bonding portion650, and is bonded to the connecting portion810of the fin base800of the other semiconductor device300at the bonding portion650.

The upper case601cand the lower case601dare provided with the refrigerant inlet13(seeFIG.16) and the refrigerant outlet14(seeFIG.16) communicating with each other in a region (not illustrated), and the upper case601cand the lower case601dare assembled to form the flow path forming body600A.

Also in the embodiment illustrated inFIG.11, in this embodiment, the variation in height position of the intermediate portions804of the connecting portions810of the upper and lower fin bases800of the semiconductor device300could be made about 0.01 mm even among the plurality of semiconductor devices300. The upper case601cand the lower case601dare bonded to the intermediate portion804of the connecting portion810of the fin base800having such a small variation. Therefore, the flow path forming body600A and the fin base800can be bonded well and efficiently in terms of strength and reliability.

InFIG.11, the semiconductor module900A is illustrated as a structure in which two semiconductor devices300are connected by one flow path forming body600A. However, the number of semiconductor devices300may be three or more, and the adjacent semiconductor devices300may be connected by the flow path forming body600A.

According to the first embodiment, the following effects are obtained.

(1) The semiconductor modules900and900A include a semiconductor device300which includes a first fin base (heat dissipation member)800having a first connecting portion810, a second fin base (heat dissipation member)800having a second connecting portion810, and a resin850for sealing the outer peripheral side surfaces of the first to fourth conductors410to413, and flow path forming bodies600and600A which are connected to the first connecting portion810of the first fin base800and the second connecting portion810of the second fin base800. The first elastically deformed portion801, which is elastically deformed, is provided such that the gap in the thickness direction between the outer peripheral end810aof the first connecting portion810of the first fin base800and the outer peripheral end810aof the second connecting portion810of the second fin base800becomes smaller than the gap in the thickness direction between the intermediate portion804of the first connecting portion810of the first fin base800and the intermediate portion804of the second connecting portion810of the second fin base800. The resin850is filled between the first connecting portion810of the first fin base800and the second connecting portion810of the second fin base800. According to this configuration, the semiconductor modules900and900A can be assembled only by connecting the flow path forming bodies600and600A and the first and second fin bases800of the semiconductor device300. Therefore, the procedure of aligning the end faces of the peripheral side portions of the upper and lower cases is not required, and the productivity of the semiconductor modules900and900A can be improved.

Since the gap in the thickness direction between the outer peripheral ends810aof the first and second fin bases800is elastically deformed to be smaller than the gap in the thickness direction between the intermediate portions804, it is possible to prevent the resin material850S from leaking to the outside from the first and second connecting portions810when molding.

(2) In the method for manufacturing the semiconductor module, the outer peripheral end810aof each of the first connecting portion810of the first fin base800and the second connecting portion of the second fin base800is brought into contact with the step (abutting portion)855of the mold852, the resin material850S is filled between the first connecting portion810of the first fin base800and the second connecting portion810of the fin base800, the first connecting portion810of the first fin base800and the second connecting portion810of the second fin base800each are elastically deformed such that the gap in the thickness direction between the intermediate portion804of the first connecting portion810of the first fin base800and the intermediate portion804of the second connecting portion810of the fin base800becomes larger than the gap in the thickness direction between the steps855.

According to this method, the first and second connecting portions810of the first and second fin bases800are elastically deformed by the pressure at the time of injection of the resin material850S. Therefore, it is not necessary to separately perform the procedure of elastically deforming the first and second connecting portions810of the first and second fin bases800, and the productivity is improved.

In addition, the resin material850S injected between the upper and lower fin bases800is suppressed from leaking at the abutting portion between the connecting portion810of the upper and lower fin bases800and the stepped portion855bor the stepped portion855a, and no leakage to the second surface858side of the step855bor step855aoccurs.

Further, the connecting portion810of the upper and lower fin bases800is elastically deformed so as to be held at a position pressed against a lower surface858of the stepped portion855of the mold852. That is, even if the gap between the connecting portions810of the upper and lower fin bases800of the pre-sealing semiconductor device configuration304varies, the Z-height positions of the intermediate portions804of all the connecting portions810of the pre-sealing semiconductor device configuration304can be set to the position of the lower surfaces858of the upper and lower molds852aand852b. Therefore, the variation in the gap between the intermediate portions804of the connecting portions810of the upper and lower fin bases800can be extremely reduced. As a result, the reliability and workability of bonding the upper and lower fin bases800and the flow path forming bodies600and600A can be improved, and thus the productivity can be improved.

FIG.12is a circuit diagram of a power conversion device using the semiconductor module according to the invention.

A power conversion device200includes inverter circuit units140and142, an inverter circuit unit43for auxiliary equipment, and a capacitor module500. The inverter circuit units140and142include a plurality of power semiconductor devices300, and form a three-phase bridge circuit by connecting them. When a current capacity is large, the semiconductor devices300are further connected in parallel, and these parallel connections are made for each phase of the three-phase inverter circuit, so that the current capacity can be increased. Further, the increase in current capacity can be coped with by connecting the active elements155and157and the diodes156and158, which are power semiconductor elements built in the semiconductor device300, in parallel.

The inverter circuit unit140and the inverter circuit unit142have the same basic circuit configuration, and the control method and operation are basically the same. Since the outline of the circuit operation of the inverter circuit unit140and the like is well known, detailed description is omitted here.

As described above, the upper arm circuit includes an active element155for the upper arm and a diode156for the upper arm as a power semiconductor element for switching. The lower arm circuit includes an active element157for the lower arm and a diode158for the lower arm as a power semiconductor element for switching. The active elements155and157receive a drive signal output from one or the other of the two driver circuits constituting a driver circuit174, perform a switching operation, and convert DC power supplied from a battery136into three-phase AC power.

As described above, the active element155for the upper arm and the active element157for the lower arm include a collector electrode, an emitter electrode, and a gate electrode. The diode156for the upper arm and the diode158for the lower arm include two electrodes, a cathode electrode and an anode electrode. As illustrated inFIG.3, the cathode electrodes of the diodes156and158are electrically connected to the collector electrodes of the IGBTs155and157, and the anode electrodes are electrically connected to the emitter electrodes of the active elements155and157, respectively. As a result, the current flow from the emitter electrode of the active element155for the upper arm and the active element157for the lower arm to the collector electrode is in the forward direction.

Further, a MOSFET (metal oxide semiconductor field effect transistor) may be used as the active element. In this case, the diode156for the upper arm and the diode158for the lower arm become unnecessary.

The positive electrode side terminal315B and the negative electrode side terminal319B of each upper/lower arm series circuit are connected to the DC terminals for connecting the capacitors of the capacitor module500, respectively. AC power is generated at each connecting portion between the upper arm circuit and the lower arm circuit, and the connecting portion between the upper arm circuit and the lower arm circuit of each upper/lower arm series circuit is connected to the AC side terminal320B of each semiconductor device300. The AC side terminal320B of each semiconductor device300of each phase is connected to the AC output terminal of the power conversion device200, and the generated AC power is supplied to the stator winding of a motor generator192or194.

A control circuit172generates a timing signal for controlling a switching timing of the active element155for the upper arm and the active element157for the lower arm based on input information from a control device or a sensor (for example, the current sensor180) on the vehicle side. The driver circuit174generates a drive signal for switching the active element155for the upper arm and the active element157for the lower arm based on the timing signal output from the control circuit172.

The upper/lower arm series circuit includes a temperature sensor (not illustrated), and the temperature information of the upper/lower arm series circuit is input to a microcomputer. Further, voltage information on the DC positive electrode side of the upper/lower arm series circuit is input to the microcomputer. The microcomputer performs over-temperature detection and over-voltage detection based on the information. If over-temperature or over-voltage is detected, the microcomputer stops the switching operations of all active elements155for the upper arm and active elements157for the lower arm, and protects the upper/lower arm series circuit from over-temperature or over-voltage.

FIG.13is an external perspective view illustrating an example of the power conversion device illustrated inFIG.12, andFIG.14is a cross-sectional view taken along line XIV-XIV of the power conversion device illustrated inFIG.13.FIG.15(a)is a perspective view of the power conversion device illustrated inFIG.14as viewed from above, andFIG.15(b)is a perspective view of the power conversion device illustrated inFIG.14as viewed from below, andFIG.16is a cross-sectional view taken along line XVI-XVI ofFIG.15(a).

The power conversion device200is composed of a lower case11and an upper case10, and includes a housing12formed in a substantially rectangular parallelepiped shape. A semiconductor module900B, the capacitor module500, and the like illustrated inFIG.15are housed inside the housing12. The semiconductor module900B includes a flow path forming body600B. A refrigerant inflow pipe13and a refrigerant outflow pipe14, communicating with the cooling flow path Cw (seeFIG.10) of the flow path forming body600B, protrude from one side surface of the housing12. As illustrated inFIG.14, the lower case11has an opening on the upper side, and the upper case10is attached to the lower case11by closing the opening of the lower case11. The upper case10and the lower case11are formed of an aluminum alloy or the like, and are sealed against the outside and fixed. The upper case10and the lower case11may be integrated. Since the housing12has a simple rectangular parallelepiped shape, it can be easily attached to a vehicle or the like and can be easily produced.

As illustrated inFIG.13, a connector17is attached to one side surface of the housing12in the longitudinal direction, and an AC terminal18is connected to the connector17. Further, a connector21is provided on the surface from which the refrigerant inflow pipe13and the refrigerant outflow pipe14are led out.

As illustrated inFIG.14, the semiconductor module900B is housed in the housing12. The control circuit172and the driver circuit174are arranged on the upper side of the semiconductor module900B, and a capacitor module500is housed on the lower side of the semiconductor module900. As illustrated inFIGS.15(a) and15(b), the semiconductor module900B has a 6in1 structure having three semiconductor devices300having a 2in1 structure. That is, one of the inverter circuit units140and142illustrated inFIG.12is included. In addition, inFIG.15(b), in order to illustrate the arrangement of the semiconductor device300, the fin base800is illustrated through the flow path forming body600.

The AC side terminal320B of the semiconductor device300penetrates the current sensor180and is bonded to a bus bar361. Further, the positive electrode side terminal315B and the negative electrode side terminal319B, which are DC terminals of the semiconductor device300, are bonded to positive and negative electrode terminals362A and362B of the capacitor module500, respectively.

In the semiconductor device300illustrated inFIG.14, the AC side terminal320B is not bent and extends straight. Further, the positive electrode side terminal315B and the negative electrode side terminal319B have a short shape cut on the root side.

The power conversion device200is manufactured to accommodate the capacitor module500in the lower case11, accommodate the semiconductor module900B manufactured in advance on the capacitor module500, and accommodate the control circuit172and the driver circuit174on the semiconductor module900B. When accommodating the semiconductor module900B, the AC side terminal320B of each semiconductor device300is bonded to the bus bar361, and the positive electrode side terminal315B and the negative electrode side terminal319B are bonded to the positive and negative electrode terminals362A and362B of the capacitor module500, respectively. When accommodating the control circuit172and the driver circuit174, the signal terminal of each semiconductor device300and the connection terminals (not illustrated) of the control circuit172and the driver circuit174are connected. The power conversion device200illustrated inFIG.13can be obtained by accommodating the semiconductor module900B, the capacitor module500, the control circuit172, and the driver circuit174in the lower case11and then sealing them with the upper case10.

As illustrated inFIGS.15(a),15(b), and16, the semiconductor module900B has an elongated rectangular parallelepiped shape. The flow path forming body600B of the semiconductor module900is formed of iron, an aluminum alloy, or the like.

As illustrated inFIG.16, the flow path forming body600B has a structure in which the flow path forming body600illustrated inFIG.10and the flow path forming body600A illustrated inFIG.11are combined, and has a flow path upper cover610, a flow path housing620, and a flow path lower cover630. The flow path housing620is provided with a frame621for connecting adjacent semiconductor devices300to each other. The flow path upper cover610and the flow path housing620are assembled by a fastening member (not illustrated). The flow path housing620and the flow path lower cover630are connected via an O-ring631to form a watertight structure.

As illustrated inFIG.11, the frame621is connected by a bonding portion650of the connecting portion810of the fin base800of each adjacent semiconductor device300, and connects the semiconductor devices300on both sides.

The flow path lower cover630is provided with the refrigerant inflow pipe13and the refrigerant outflow pipe14. The flow path housing620is formed with a flow through path612that penetrates the frame621in the thickness (Z direction). The refrigerant flowing in from the refrigerant inflow pipe13flows through the flow path provided between the lower surface (Z direction) of each semiconductor device300and the flow path lower cover630to cool down each semiconductor device300from the lower side. Further, the refrigerant flowing in from the refrigerant inflow pipe13flows through the flow path provided between the upper surface (−Z direction) of each semiconductor device300and the flow path upper cover610via the flow through path612to cool down each semiconductor device300from above. The refrigerant that cools each semiconductor device300from the upper side and the lower side flows out from the refrigerant outflow pipe14. The cooling flow path Cw for cooling each semiconductor device300is formed in the flow path lower cover630, the flow path housing620, and the flow path upper cover610.

In this way, the power conversion device200having a 6in1 structure is formed by using three semiconductor devices300having a 2in1 structure.

Second Embodiment

FIG.17is a cross-sectional view illustrating a second embodiment of the semiconductor module according to the invention.

In the second embodiment, a thick portion811is provided in the intermediate portion804of the connecting portion810of the fin base800of the semiconductor device300.

The thick portion811is provided so as to project to the side opposite to the flow path forming body600A side of the connecting portion810. Since the thick portion811is provided in the intermediate portion804between the first elastically deformed portion801and the third elastically deformed portion803, the connecting portion810can be elastically deformed by the first to third elastically deformed portions801to803without inhibiting the elastic deformation of the connecting portion810. When the connecting portion810of the fin base800and the flow path forming body600A are bonded by laser welding, the laser may penetrate the connecting portion810of the fin base800and the flow path forming body600A in the thickness direction due to the variation in the laser output. By providing the thick portion811in the connecting portion810of the fin base800, it is possible to suppress such penetration of the laser and secure the bonding strength.

Other configurations in the second embodiment are similar to those in the first embodiment.

Therefore, the second embodiment has the same effect as that of the first embodiment.

Third Embodiment

FIG.18(a)is a cross-sectional view of a third embodiment of the semiconductor module according to the invention, andFIG.18(b)is an enlarged cross-sectional view of a process of molding the connecting portion of the fin base illustrated inFIG.18(a).

In the third embodiment, the semiconductor device300has a structure in which a recess812having a triangular cross section is provided in the intermediate portion804of the connecting portion810of the fin base800. The recess812is provided in an annular shape over the entire circumference at substantially the center of the width (length in the X direction) of the intermediate portion804of the connecting portion810, and the connecting portion810is divided into two flat portions extending in the X direction and the −X direction with the recess812as a boundary.

The mold852is provided with a protrusion860having a triangular cross section for forming the recess812in an annular shape over the entire circumference.

When the resin material850S is injected into the mold852, the resin material850S is filled between the connecting portions810of the upper and lower fin bases800, and the connecting portion810of each fin base800is pressed to the second surface858of the stepped portion855bby the resin pressure. Since the mold852is formed with the protrusion860, the connecting portion810is formed with elastically deformed portions805,806, and807at the top and the root portions on both sides of the top, which are the corners of the protrusion860, respectively, and this state is maintained.

As illustrated inFIG.18(a), the upper and lower cases601of the flow path forming body600A are respectively bonded to the connecting portion810of the fin base800of each semiconductor device300by two bonding portions650. The two bonding portions650are provided one by one in the area of the flat portion in the X direction and the region of the flat portion in the −X direction of the recess812of the connecting portion810.

In this way, the connecting portion810of one fin base800is bonded to each case601of the flow path forming body600at two places to ensure the reliability of the connection strength and to improve watertight performance.

The other configurations in the third embodiment are the same as those in the first embodiment.

Therefore, the third embodiment has the same effect as that of the first embodiment.

In the above embodiment, the semiconductor modules900and900A are exemplified as a 2in1 structure in which a pair of upper arms and a lower circuit is provided or a 6in1 structure in which three pairs are provided. However, the semiconductor modules900and900A can also have a 3in1 structure or a 4in1 structure.

The 3in1 structure has, for example, a structure in which three upper arm circuits are packaged, or a structure in which three lower arm circuits are packaged. A semiconductor module having a 6in1 structure can be formed by combining an upper arm package in which three upper arm circuits are packaged and a lower arm package in which three lower arm circuits are packaged.

In the above embodiment, the structure has been exemplified in which the first to fourth conductors410to413and the wirings452and454of the wiring boards422and423are bonded, and the wirings452and454of the wiring boards422and423and the fin base800are bonded by the metal bonding member51. However, instead of bonding with the metal bonding member51, other bonding methods such as conductive adhesive, welding, and melt bonding by ion beam irradiation may be used.

Various embodiments and modifications have been described, but the invention is not limited to these contents. The various embodiments described above and modifications may be combined, or changes may be added as appropriate, and other aspects considered within the scope of the technical idea of the invention are also included within the scope of the invention.

REFERENCE SIGNS LIST