JP2014135527A - Semiconductor power module and method for manufacturing the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a semiconductor power module which levels a current flowed from a semiconductor power device and effectively radiates heat generated in the semiconductor power device, and to provide a method for manufacturing the semiconductor power module.SOLUTION: In a power module 1, a power device 18 is joined to a base part 8 of a case 2, and a metal block 24 is joined to a surface 181 of the power device 18. A source terminal 4 for supplying electric power to the power device 18 is joined to the metal block 24. This structure levels a current flowed from the power device 18 and radiates heat generated in the power device 18 effectively.

Description

  The present invention relates to a semiconductor power module and a manufacturing method thereof.

A semiconductor power module is an apparatus that mounts a plurality of semiconductor power devices and obtains output from the semiconductor power devices that are electrically connected to each other. Such a semiconductor power module is used, for example, in an inverter circuit constituting a drive circuit for driving an electric motor. The electric motor is used as a power source of, for example, an electric vehicle (including a hybrid vehicle), a train, an industrial robot, and the like. The semiconductor power module is also applied to an inverter circuit that converts electric power generated by a solar battery, a wind power generator, and other power generation devices (particularly, a private power generation device) so as to match the power of a commercial power source.

A semiconductor power device mounted on the semiconductor power module is connected to an external terminal of the module via a wire wiring.
For example, the semiconductor power module disclosed in FIG. 1 of Patent Document 1 includes a metal substrate electrode,
A circuit board having a structure in which an insulating substrate and a heat sink are integrated; a plurality of SiC semiconductor power devices connected on metal substrate electrodes of the circuit board; and a case fixed to the heat sink and containing the SiC semiconductor power device; And an external electrode attached to the case. The SiC semiconductor power device and the external electrode are connected to each other by an Al wire.

JP 2007-305962 A

Since it is necessary to flow a large current handled by the semiconductor power device, a plurality of Al wires connected to the semiconductor power device are usually bonded to one chip of the device.
However, even if a plurality of Al wires are bonded, the current is concentrated at the bonding portion between the Al wires and the device because the bonding area between the individual Al wires and the semiconductor power device is small. Due to this current concentration, there is a problem that the current waveform is disturbed and further the device generates heat locally. Part of the heat generated in the device is dissipated through the Al wire, but the heat dissipation effect is not sufficient with a thin wire.

If the number of Al wires connected per chip of the device is increased and thereby a large bonding area is secured, a sufficient heat dissipation effect may be obtained. However, since the pitch of the Al wires connected to the device is limited, it is desired to improve the heat dissipation effect by another method.
Accordingly, a main object of the present invention is to provide a semiconductor power module capable of leveling the current flowing from the semiconductor power device, and efficiently dissipating heat generated in the semiconductor power device, and a method for manufacturing the same. That is.

Another object of the present invention is to provide a semiconductor power module that can level the current flowing from the semiconductor power device and can efficiently dissipate the heat generated by the semiconductor power device. It is providing the manufacturing method of the semiconductor power module which can be manufactured.

The invention according to claim 1 for achieving the above object has a base member, a semiconductor power device having a front surface and a back surface, the back surface being joined to the base member, and a front surface and a back surface, the back surface Is bonded to the surface of the semiconductor power device, rises in a direction away from the base member from the surface of the semiconductor power device, and is used as a wiring member for the semiconductor power device, and the surface of the metal block And an external terminal for supplying electric power to the semiconductor power device through the metal block.

According to this configuration, a metal block having a diameter larger than that of the wire is used as a wiring member that connects the semiconductor power device and the external terminal of the module. Thereby, wiring can be joined to a semiconductor power device with a large area. Therefore, the occurrence of current concentration at the junction between the wiring (metal block) and the semiconductor power device can be suppressed. As a result, the current can be leveled. Furthermore, since the heat generated in the semiconductor power device can be efficiently dissipated, the heat dissipation effect can be improved.

According to a second aspect of the present invention, there is provided a case having a base portion having a device region in which the semiconductor power device is disposed, a frame portion fixed to the base portion and surrounding the device region, A resin-made top plate fixed to the frame part and facing the device region; and the external terminal includes a plate terminal provided along the top plate,
2. The semiconductor power module according to claim 1, wherein the top plate has a support portion that overlaps the plate terminal in a plan view and supports the plate terminal from the back side.

When the external terminal is a plate terminal provided along the top plate that closes the case, when the plate terminal receives an impact from the outside, the impact is transmitted to the semiconductor power device through the metal block, and as a result, The device may be destroyed.
Therefore, in the invention described in claim 2, the top plate has a support portion for supporting the plate terminal from the back surface side. Thereby, even if a plate terminal receives an impact etc., the impact can be relieved by a support part. As a result, the impact can be prevented from being transmitted to the semiconductor power device at all, or the impact transmitted to the semiconductor device can be reduced. Therefore, destruction of the semiconductor power device due to impact can be prevented.

According to a third aspect of the present invention, in the top plate, an opening smaller than a planar area of the plate terminal is formed in a region facing the plate terminal, and the metal block passes through the opening. The semiconductor power module according to claim 2, wherein the support portion of the top plate includes a peripheral portion of the opening in the top plate.
According to this structure, by the support part comprised by the peripheral part of the opening surrounding a metal block,
The impact transmitted from the plate terminal to the metal block can be effectively mitigated.

The invention according to claim 4 is the semiconductor power module according to claim 2 or 3, wherein the top plate is a member provided so as to be separable from the frame portion.
According to this configuration, since the top plate can be separated from the frame portion, when manufacturing the semiconductor power module, the semiconductor power device is first arranged in the device region in a state where the frame portion and the top plate are separated, A metal block can be joined to the semiconductor power device. Therefore, workability is good.

According to a fifth aspect of the present invention, the top plate has an open end at a position on one side with respect to the plate terminal, and has a closed end at a position opposite to the open end with respect to the plate terminal. The closed end is slidably supported by the frame portion in a sliding direction along a direction away from the plate terminal, and the metal block includes the open end and the closed end. 3. The semiconductor power according to claim 2, wherein the support portion of the top plate includes an edge portion of the region of the top plate. It is a module.

According to this configuration, the top plate is supported so as to be slidable with respect to the frame portion, and can be separated from the frame portion. Therefore, when the semiconductor power module is manufactured, the semiconductor power device can be first disposed in the device region in a state where the frame portion and the top plate are separated, and the metal block can be bonded to the semiconductor power device. Therefore, workability is good. In addition, the end of the top plate opposite to the direction pulled out by the slide is an open end. Therefore, even after the top plate is fixed to the frame portion, the device region can be exposed by pulling out the top plate without removing the connection between the metal block and the plate terminal. As a result, maintenance inside the case can be easily performed.

Moreover, the impact transmitted from the plate terminal to the metal block can be effectively mitigated by the support portion constituted by the edge portion surrounding the region where the metal block is disposed.
According to a sixth aspect of the present invention, the plate terminal is formed in a square shape in a plan view having a pair of first opposite sides extending along the sliding direction and a pair of second opposite sides orthogonal to the first opposite sides. The top plate has a pair of arm portions along the first opposite side and a connecting portion that connects the sliding direction one sides of the pair of arm portions, and the plate is formed by the arm portion and the connecting portion. A pair of the arm portions are provided so as to surround the three sides around the terminal, respectively, and a first portion that abuts from the laterally outer side perpendicular to the sliding direction with respect to the peripheral portion of the plate terminal, A second portion extending from the lower end of the first portion along the back surface of the plate terminal, and the peripheral portion along the first opposite side of the plate terminal is the first portion of the arm portion. Part and fitted in the partitioned recesses in said second portion of said arm portion, a semiconductor power module according to claim 5.

According to this configuration, the peripheral edge portion along the first opposite side of the plate terminal is fitted into the recess defined by the first portion of the arm portion and the second portion of the arm portion. Therefore, when the top plate is slid along the frame portion, the plate terminal can be used as a guide member for guiding the top plate. Therefore, the top plate can be easily positioned.
According to a seventh aspect of the present invention, the connecting portion includes a first portion that comes into contact with the peripheral portion of the plate terminal from the outside in the sliding direction, and the back surface of the plate terminal from the lower end of the first portion. And the peripheral portion along the second opposite side of the plate terminal is partitioned by the first portion of the connecting portion and the second portion of the connecting portion. The semiconductor power module according to claim 6, wherein the semiconductor power module is fitted in the recessed portion.

According to this configuration, the peripheral edge portion along the second opposite side (the opposite side perpendicular to the sliding direction) of the plate terminal is fitted into the recess defined by the first portion of the connecting portion and the second portion of the connecting portion. Yes. Therefore, when the top plate is slid along the frame portion, the top plate can be stopped from sliding by bringing the peripheral edge portion of the plate terminal into contact with the first portion of the connecting portion of the top plate. That is, the plate terminal can be used as a stopper member for stopping the sliding of the top plate. Therefore, the top plate can be positioned more easily.

Moreover, as for the invention of Claim 8, both the said base part and the said frame part are metal,
The base part also serves as the base member that supports the semiconductor power device, and the frame part supplies second power to the semiconductor power device via the base part.
The semiconductor power module according to claim 2, which also serves as an external terminal.

According to this configuration, the frame portion rising from the base portion also serves as the second external terminal.
Electrical contact to the back surface of the semiconductor power device can be made from the front surface side of the semiconductor power module.
The semiconductor power device may be a device using a SiC semiconductor.

In this case, the metal block is preferably made of Cu or an alloy material containing Cu as in the invention described in claim 10.
According to this configuration, the difference in coefficient of linear expansion between SiC and the wiring member can be reduced as compared with the case where an Al wire is used as the wiring member of the semiconductor power device. Therefore, it is possible to reduce the generation of thermal stress generated between the semiconductor power device and the wiring member. As a result, since thermal fatigue of the device can be reduced, a semiconductor power module having a long life and high reliability can be achieved. Examples of the alloy material containing Cu include a CuMo alloy and a CuW alloy.

For example, the linear expansion coefficient of SiC is about 4.5 ppm / K, and the linear expansion coefficient of CuMo alloy is about 9.0 ppm / K (about twice that of SiC). On the other hand, the linear expansion coefficient of Al is about 23 ppm / K (about 5 times that of SiC).
The metal block may have a rectangular parallelepiped shape as in the invention described in claim 11, or a taper whose cross-sectional area is widened from the back surface to the surface as in the invention of claim 12. You may have a shape.

If the metal block has a tapered shape, the area of the back surface is designed according to the surface area of the semiconductor power device, and the surface area is designed according to the size of the external terminal, the heat generated by the device is optimized. Can be dissipated with high heat dissipation efficiency.
According to a thirteenth aspect of the present invention, the semiconductor power module includes a plurality of the semiconductor power devices, and the external terminals are collectively connected to a metal block joined to each of the semiconductor power devices. It may be joined.

According to a fourteenth aspect of the present invention, in the top plate, a through-hole penetrating in the thickness direction is formed in a region outside the region overlapping the plate terminal in plan view. A semiconductor power module according to claim 1.
According to this configuration, the insulating state in the case can be easily maintained by pouring the resin into the case from the through hole formed in the top plate.

The invention according to claim 15 includes a step of bonding the back surface of a semiconductor power device having a front surface and a back surface to a base member, and a front surface and a back surface after bonding the base member and the semiconductor power device, A step of joining the back surface of the metal block used as a wiring member for a semiconductor power device to the surface of the semiconductor device, and pre-soldering to an external terminal for supplying power to the semiconductor power device And applying the metal block to the place where the preliminary solder is applied to the external terminal,
A method of manufacturing a semiconductor power module, comprising the step of joining the external terminal and the metal block by heating the external terminal.

As in the present invention, when using a metal block with a high heat dissipation effect as a wiring material for a semiconductor power device, a solder material is sandwiched between the metal block and the external terminal, and the external terminal side is simply heated. Heat may be dissipated through a metal block with a high heat dissipation effect. As a result, the solder material sandwiched in advance does not melt well, and there is a risk of poor bonding between the metal block and the external terminal.

Therefore, in the invention according to claim 15, preliminary soldering is performed in advance on the external terminal,
The metal block is brought into contact with and joined to the portion where the preliminary solder is applied. Thereby, a metal block and an external terminal can be joined favorably. That is, the semiconductor power device as in the present invention can be manufactured easily and with high quality.
In the invention described in claim 16, the external terminal is a flat plate terminal, and the step of applying the preliminary soldering includes a step of depositing a predetermined amount or more of solder on the plate terminal. It is a manufacturing method of the semiconductor power module as described in (4).

According to this configuration, even when a height difference occurs between the plurality of metal blocks, the height difference can be compensated for by a predetermined amount or more of solder.

1 is an overall view of a power module according to a first embodiment of the present invention. It is an internal block diagram of the power module shown in FIG. It is sectional drawing of the power module shown in FIG. 1, Comprising: The cross section in the AA cut surface of FIG. 1 is represented. It is sectional drawing which shows a part of manufacturing process of the power module shown in FIG. 1, Comprising: The same cut surface as FIG. 3 is represented. It is a figure which shows the next process of FIG. 4A. It is a figure which shows the next process of FIG. 4B. It is a figure which shows the next process of FIG. 4C. It is a figure which shows the next process of FIG. 4D. It is sectional drawing of the power module shown in FIG. 1, Comprising: The cross section in the A'-A 'cut surface of FIG. 1 is represented. It is a general view of the power module which concerns on 2nd Embodiment of this invention. It is an internal block diagram of the power module shown in FIG. It is sectional drawing of the power module shown in FIG. 6, Comprising: The cross section in the BB cut surface of FIG. 6 is represented. It is sectional drawing of the power module shown in FIG. 6, Comprising: The cross section in the CC cut surface of FIG. 6 is represented. FIG. 7 is a cross-sectional view showing a part of the manufacturing process of the power module shown in FIG. 6 and showing the same cut surface as FIG. 7. It is a figure which shows the next | following process of FIG. 10A. It is a figure which shows the next process of FIG. 10B. It is a figure which shows the next process of FIG. 10C. FIG. 10D is a diagram showing a step subsequent to FIG. 10D. It is an internal block diagram of the power module which shows the modification of the metal block shown in FIG. It is sectional drawing of the power module which shows the modification of the metal block shown in FIG.

Hereinafter, embodiments of the present invention will be described in detail with reference to the accompanying drawings.
<First Embodiment>
FIG. 1 is an overall view of a power module according to a first embodiment of the present invention.
The power module 1 includes a case 2 having an open surface, a top plate 3 that closes the open surface of the case, a source terminal 4 as an external terminal, a source sense terminal 5, and a gate terminal 6.

For convenience of explanation, the X direction, the Y direction, and the Z direction shown in FIG. The X direction is a direction along the long side of the case 2 that is rectangular in plan view. The Y direction is a direction along the short side of the case 2 that is rectangular in plan view. The Z direction is a direction along the height direction of the case 2. When the case 2 is placed on a horizontal plane, the X direction and the Y direction are two horizontal straight lines (
Two horizontal directions (first horizontal direction and second horizontal direction) along the X axis and the Y axis), and Z
The direction is a vertical direction (height direction) along a vertical straight line (Z axis).

The case 2 integrally has a base portion 8 having a rectangular thickness in plan view and a frame portion 9 having a rectangular shape in plan view standing from the peripheral edge of the base portion 8. In the power module 1, a power device 18, which will be described later, is disposed in a region (device region 16, which will be described later) surrounded by the frame portion 9 in the base portion 8.
In this embodiment, the base portion 8 and the frame portion 9 are made of a metal material. In particular,
It is preferably made of a metal with high heat dissipation such as aluminum or copper.

A pedestal 12 made of a resin material is attached to the frame portion 9. A thin cylindrical source sense terminal 5 and a gate terminal 6 are provided across the inside and outside of the case 2 through the pedestal 12. By providing the source sense terminal 5 and the gate terminal 6 via the resin base 12, the source sense terminal 5 and the gate terminal 6 can be insulated from each other and the metal frame portion 9.

The top plate 3 is a plate-like body with a uniform thickness that is separable from the case 2 in a plan view. In this embodiment, the top plate 3 is made of a resin material. In particular, a heat resistant resin such as PPS (polyphenylene sulfide) is preferably used, but a liquid crystal polymer, a ceramic material, or the like may be used. The top plate 3 is fixed to the frame portion 9 using, for example, an adhesive.

The source terminal 4 is a plate-like body (plate terminal) having a uniform rectangular shape in a plan view that is long along the Y direction.
It is placed on the top surface of the top plate 3.
In the top plate 3, a plurality of openings 14 (two-dot chain lines in FIG. 1) smaller than the planar area of the source terminal 4 are formed in a region facing the source terminal 4. The plurality of openings 14 are formed in the same number as the number of power devices 18 described later. In this embodiment, three openings 14
Are arranged in a triangular shape in plan view.

In the top plate 3, a through-hole 15 that penetrates the top plate 3 in the thickness direction is formed at a position between the source terminal 4 and the base 12. In this embodiment, the through-hole 15 is formed in a long oval shape in plan view along the Y direction.
FIG. 2 is an internal configuration diagram of the semiconductor power module shown in FIG. 3 is a cross-sectional view of the semiconductor power module shown in FIG. 1 and shows a cross section taken along the line AA of FIG.

In the case 2, in the device region 16 surrounded by the frame portion 9, the insulating substrate 17 and the plurality of power devices 18 are arranged in this order from the side of the base 12 along the Y direction.
The insulating substrate 17 is made of, for example, a ceramic substrate. This insulating substrate 17 is
A plate-like body having a uniform rectangular shape in a plan view that is long along the Y direction, on which plate-like source sense wirings 19 and gate wirings 20 are formed with a space therebetween. One end of the source sense terminal 5 is connected to the source sense wiring 19. One end of the gate terminal 6 is connected to the gate wiring 20.

The plurality of power devices 18 include a plurality of switching elements Tr and a plurality of diode elements Di. In this embodiment, two switching elements Tr and one diode element Di are included. In this embodiment, the power device 18 is a device using a SiC semiconductor. The plurality of power devices 18 are respectively connected to the opening 1 of the top plate 3.
4 are arranged in a one-to-one correspondence. Specifically, one diode element Di and two switching elements Tr are arranged in a triangular shape in plan view. The plurality of power devices 18 are electrically connected to the case 2 by joining the back surfaces 182 to the base portion 8 of the case 2.

In the power device 18, the switching element Tr is electrically connected to the gate wiring 20 and the source sense wiring 19 using separate Al wires 22 and 23, respectively.
On the surface 181 of each power device 18 (surface opposite to the surface joined to the base portion 8),
The back surfaces 242 of the metal blocks 24 used as wiring materials for supplying power to the power device 18 are joined one by one. In this embodiment, the metal block 24 has a rectangular parallelepiped shape that rises from the surface 181 of the power device 18 in a direction away from the base portion 8 (a direction approaching the source terminal 4).

The metal block 24 is made of Cu or an alloy material containing Cu (as an alloy material, for example,
CuMo alloy, CuW alloy, etc. are mentioned. ). This
Compared to the case where an Al wire is used as the wiring member of the SiC power device 18, SiC is used.
And the difference in linear expansion coefficient between the metal block 24 can be reduced. Therefore, it is possible to reduce the generation of thermal stress generated between the power device 18 and the metal block 24. As a result, since the thermal fatigue of the device can be reduced, the power module 1 has a long life and high reliability.
Can be achieved. For example, the coefficient of linear expansion of SiC is about 4.5 ppm / K,
The coefficient of linear expansion of the CuMo alloy is about 9.0 ppm / K (about twice that of SiC). On the other hand, Al
The linear expansion coefficient is about 23 ppm / K (about 5 times that of SiC). The plurality of metal blocks 24 have their surfaces 241 joined to the source terminals 4 through the openings 14 of the top plate 3.

Further, in the top plate 3, a recess 25 having an outline along the shape of the source terminal 4 in plan view (overlapping the source terminal 4 in plan view) is formed in a region facing the source terminal 4.
The source terminal 4 is fitted in the recess 25. The opening 14 for connecting the metal block 24 and the source terminal 4 is formed so as to penetrate the bottom wall 26 of the recess 25.
A portion surrounding the opening 14 in the bottom wall 26 of the concave portion 25 as a support portion is in contact with the source terminal 4 from the back surface side. Thereby, a part of the source terminal 4 is supported by the metal block 24 by bonding, and the remaining most part is supported by the top plate 3 (the bottom wall 26 of the recess 25) that enters the back side thereof.

4A to 4E are diagrams for explaining the manufacturing steps of the power module shown in FIG. 1 in the order of steps.
First, as shown in FIG. 4A, an insulating substrate 17 on which plate-like wiring is formed is attached to the device region 16 in the case 2. Next, the base 12 into which the source sense terminal 5 and the gate terminal 6 are inserted is attached to the frame portion 9 of the case 2. Subsequently, the source sense terminal 5 and the gate terminal 6 are joined to the plate-like wirings 19 to 20. Next, each power device 18 is set on the base portion 8 via, for example, the plate solder 27. And case 2 is carried in on the heater 28, for example, is heated at 250-400 degreeC. By this heating, the heat transmitted to the metal case 2 is transmitted to the sheet solder 27 and the sheet solder 27 is melted. Thereby, the power device 18 is joined to the base portion 8 of the case 2. In FIG. 4B and subsequent figures, the plate solder 27 used for joining is omitted.

Next, with the case 2 placed on the heater 28, as shown in FIG. 4B, the metal block 24 is set on the surface 181 of each power device 18 via, for example, a sheet solder 29. And case 2 is heated at 250-400 ° C, for example. By this heating, the heat transferred to the metal case 2 is transferred to the plate solder 29 via the power device 18 and the plate solder 29 is melted. Thereby, the metal block 24 is joined to the power device 18. In FIG. 4C and subsequent figures, the sheet solder 29 used for joining is omitted.

Next, as shown in FIG. 4C, the top plate 3 is positioned so that the openings 14 of the top plate 3 coincide with the metal blocks 24, and the top plate 3 is fixed to the frame portion 9.
Next, as shown in FIG. 4D, the source terminal 4 is placed alone on the heater 28, and the preliminary solder 30 is applied on the source terminal 4. Next, the metal block 24 is positioned with respect to the preliminary solder 30 in a state in which the case 2 is turned upside down (a state in which the top plate 3 is on the lower side),
The metal block 24 and the preliminary solder 30 are brought into contact with each other.

Then, the metal block 24 and the source terminal 4 are joined by heating the heater 28 as shown in FIG. 4E.
As described above, according to the power module 1, the metal block 24 having a diameter larger than that of the wire is used as a wiring member that connects the power device 18 and the source terminal 4. Thereby, the wiring (metal block 24) can be bonded to the power device 18 in a large area. Therefore, the occurrence of current concentration at the junction between the wiring (metal block 24) and the power device 18 can be suppressed. As a result, the current can be leveled. Furthermore, since the heat generated in the power device 18 can be efficiently dissipated by the metal block 24 and the plate-like source terminal 4, the heat dissipation effect can be improved.

Further, when the external terminal is a plate terminal provided along the upper surface of the top plate 3 as in this embodiment, when the source terminal 4 receives an impact from the outside, the impact is applied to the metal block 24. To the power device 18 and, as a result, the device 18 may be destroyed.
Therefore, in this embodiment, the bottom wall 26 of the concave portion 25 of the top plate 3 supports the source terminal 4 from the back surface side. Thereby, even if the source terminal 4 receives an impact or the like, the impact can be mitigated by the bottom wall 26 of the recess 25. As a result, the impact can be prevented from being transmitted to the power device 18 at all, or the impact transmitted to the power device 18 can be reduced. Therefore, destruction of the power device 18 due to impact can be prevented. In addition, in this embodiment, the support portion that supports the source terminal 4 is the peripheral portion (the bottom wall 26 of the recess 25) of the opening 14 that surrounds each metal block 24 in a one-to-one manner along the planar contour of each metal block. Since it is configured, the impact transmitted from the source terminal 4 to the metal block 24 can be effectively mitigated.

Further, since the top plate 3 can be separated from the frame portion 9, when the power module 1 is manufactured, the power device 18 is first arranged in the device region 16 with the frame portion 9 and the top plate 3 being separated. The metal block 24 can be joined to the power device 18. Therefore, workability is good.
Further, since the back surface 182 of the power device 18 is directly joined to the metal base portion 8, electrical contact with the back surface 182 (drain side) of the power device 18 is made using the case 2 of the power module 1. Can take.

Moreover, since the through-hole 15 is formed in the top plate 3, the insulating state in the case 2 can be easily maintained by pouring the resin from the through-hole 15 into the case 2.
Further, as in this embodiment, the metal block 24 having a high heat dissipation effect is replaced with the power device 18.
4A and 4B, the source terminal 4 is heated by the heater 28 with the plate solder sandwiched between the metal block 24 and the source terminal 4 as shown in FIGS. 4A and 4B. Then, the heat may be dissipated through the metal block 24 having a high heat dissipation effect. As a result, the preliminarily sandwiched sheet solder does not melt well, and there is a risk of poor bonding between the metal block 24 and the source terminal 4.

Therefore, in this embodiment, as shown in FIG. 4D, the preliminary solder 30 is applied in advance to the source terminal 4, and the metal block 24 is brought into contact with and joined to the portion where the preliminary solder 30 is applied. Thereby, the metal block 24 and an external terminal can be favorably joined. That is, the power module 1 can be manufactured easily and with high quality.
According to such a method, for example, even if a height difference h as shown in FIG. 5 occurs between the plurality of metal blocks 24, the height difference h can be obtained by applying a predetermined amount of preliminary solder 30. Can be supplemented by the preliminary solder 30. As a result, the plate-like source terminals 4 can be reliably bonded together to the plurality of metal blocks 24.
<Second Embodiment>
FIG. 6 is an overall view of a power module according to the second embodiment of the present invention. 7 is similar to FIG.
It is an internal block diagram of the power module shown in FIG. 8 is a cross-sectional view of the power module shown in FIG. 6 and shows a cross section taken along the line BB of FIG. 9 is a cross-sectional view of the power module shown in FIG. 6 and shows a cross section taken along the line CC in FIG.

The power module 51 includes a case 52 having an open surface, a top plate 53 that closes the open surface of the case 52, a source terminal 54 as an external terminal, a source sense terminal 55, and a gate terminal 56. .
For convenience of explanation, the X direction, the Y direction, and the Z direction shown in FIG. The X direction is a direction along the long side of the case 52 that is rectangular in plan view. The Y direction is a direction along the short side of the case 52 that is rectangular in plan view. The Z direction is a direction along the height direction of the case 52. When the case 52 is placed on a horizontal plane, the X direction and the Y direction become two horizontal directions (first horizontal direction and second horizontal direction) along two horizontal straight lines (X axis and Y axis) orthogonal to each other, and Z The direction is a vertical direction (height direction) along a vertical straight line (Z axis).

The case 52 includes a base portion 58 having a uniform thickness in a plan view rectangle and a frame portion 59 having a rectangular shape in a plan view standing from the peripheral edge of the base portion 58. In the power module 51, a power device 74 to be described later is arranged in a region (device region 61) surrounded by a frame portion 59 that is included in the base portion 58.
In this embodiment, the base portion 58 is made of a metal material. In particular, it is preferably made of a metal with high heat dissipation such as aluminum or copper.

On the other hand, the frame part 59 is comprised with the resin material in this embodiment. In particular, PPS (
It is preferable to use a heat-resistant resin such as polyphenylene sulfide, but a liquid crystal polymer, a ceramic material, or the like may be used.
The frame portion 59 is formed with a low step portion 63 having a constant depth one step lower than the top portion thereof. The low step portion 63 is formed in a U shape in plan view, and is a portion for sliding the top plate 53 which is also in U shape in plan view. The depth of the low step portion 63 is preferably approximately the same as the thickness of the top plate 53, for example. As a result, when the top 53 is fixed, the frame 59 and the top 5
3 can form a rectangular parallelepiped having a flat surface.

A pedestal 64 made of a resin material is attached to the frame portion 59. A thin bar-like source sense terminal 55 and a gate terminal 56 are provided across the inside and outside of the case 52 through the pedestal 64. By providing the source sense terminal 55 and the gate terminal 56 via the resin pedestal 64, the source sense terminal 55 and the gate terminal 56 can be insulated from each other and the metal frame portion 59.

The top plate 53 is a plate-like body with a uniform thickness that is separable from the case 52 and has a rectangular shape in plan view.
In this embodiment, the top plate 53 is made of a resin material. In particular, a heat resistant resin such as PPS (polyphenylene sulfide) is preferably used, but a liquid crystal polymer, a ceramic material, or the like may be used.
The source terminal 54 is a plate-like body (plate terminal) having a uniform thickness that is long in plan view along the Y direction, and is provided so as to face the device region 61 of the base portion 58.

The top plate 53 includes a pair of arm portions 65 extending along the long side as the first opposite side of the source terminal 54, and a connecting portion 66 that connects the source sense terminals 55 side to the source terminal 54 in the pair of arm portions 65. The arm portion 65 and the connecting portion 66 are provided so as to surround the three sides around the plate terminal, and the X-direction source sense terminal 55 side is a closed end closed by the connecting portion 66, and vice versa. The side is an open end. This
The top plate 53 is supported by the frame portion 59 so as to be slidable in the sliding direction (X direction) along the direction in which the connecting end is separated from the source terminal 54.

Then, as shown in FIG. 9, the pair of arm portions 65 are respectively in contact with the peripheral portion of the source terminal 54 from the first portion 67 that abuts from the outside in the lateral direction (Y direction) perpendicular to the sliding direction.
The second portion 68 extends from the lower end of the first portion 67 along the back surface of the source terminal 54. As a result, the peripheral portion along the long side of the source terminal 54 is aligned with the first portion 6 of the arm portion 65.
7 and the recess 69 defined by the second portion 68 of the arm 65.

Further, as shown in FIG. 8, the connecting portion 66 includes a first portion 70 that comes into contact with the peripheral portion of the source terminal 54 from the outside in the sliding direction (X direction), and a source terminal from the lower end of the first portion 70. 54 and a second portion 71 projecting along the back surface. As a result, the source terminal 54
The peripheral portion along the short side as the second opposite side of the first portion 70 of the connecting portion 66 and the second portion of the connecting portion 66
It fits into a recess 72 defined by a portion 71.

That is, the source terminal 54 is supported by the arm portion 65 and the connecting portion 66 at a U-shaped position in plan view.
In the case 52, in the device region 61 surrounded by the frame portion 59, an insulating substrate 73 and a plurality of power devices 74 are arranged in this order from the side of the base 64 along the Y direction.

The insulating substrate 73 is made of, for example, a ceramic substrate. This insulating substrate 73 is
A plate-like body having a uniform rectangular shape in a plan view that is long along the Y direction, on which plate-like source sense wirings 75 and gate wirings 76 are formed with a space therebetween. One end of a source sense terminal 55 is connected to the source sense wiring 75. One end of the gate terminal 56 is connected to the gate wiring 76.

The plurality of power devices 74 include a plurality of switching elements Tr and a plurality of diode elements Di. In this embodiment, two switching elements Tr and one diode element Di are included. In this embodiment, the power device 74 is a device using a SiC semiconductor. In the plurality of power devices 74, two switching elements Tr are arranged at intervals along the Y direction, and one diode element Di is provided on the opposite side of the X-direction insulating substrate 73 with respect to these switching elements Tr. Is arranged. Specifically, 1
The two diode elements Di and the two switching elements Tr are arranged in a triangular shape in plan view. The plurality of power devices 74 are electrically connected to the case 52 by joining back surfaces 742 thereof to the base portion 58 of the case 52.

In the power device 74, the switching element Tr is electrically connected to the gate wiring 76 and the source sense wiring 75 using separate Al wires 81 and 82, respectively.
The back surface 832 of the metal block 83 used as a wiring material for supplying power to the power device 74 is bonded to the front surface 741 (surface opposite to the surface bonded to the base portion 58) of each power device 74 one by one. ing. In this embodiment, the metal block 83 has a rectangular parallelepiped shape that rises from the surface 741 of the power device 74 in a direction away from the base portion 58 (direction approaching the source terminal 54).

The metal block 83 is made of Cu or an alloy material containing Cu (as an alloy material, for example,
CuMo alloy, CuW alloy, etc. are mentioned. ). This
Compared to the case where an Al wire is used as the wiring member of the SiC power device 74, SiC is used.
And the difference in linear expansion coefficient between the metal block 83 can be reduced. Therefore, the generation of thermal stress generated between the power device 74 and the metal block 83 can be reduced. As a result, since the thermal fatigue of the device can be reduced, the power module 5 having a long life and high reliability is achieved.
1 can be achieved. For example, the linear expansion coefficient of SiC is about 4.5 ppm / K, and the linear expansion coefficient of CuMo alloy is about 9.0 ppm / K (about twice that of SiC). On the other hand, A
The linear expansion coefficient of l is about 23 ppm / K (about 5 times that of SiC). The plurality of metal blocks 83 are regions surrounded by the arm portion 65 and the connecting portion 66 in the top plate 53, and the surface 831 is joined to the source terminal 54.

10A to 10E are diagrams for explaining the manufacturing process of the power module shown in FIG. 6 in the order of steps.
First, as shown in FIG. 10A, an insulating substrate 73 on which plate-like wiring is formed is attached to the device region 61 in the case 52. Next, the base 64 into which the source sense terminal 55 and the gate terminal 56 are inserted is attached to the frame portion 59 of the case 52. Subsequently, the source sense terminal 55 and the gate terminal 56 are joined to the plate wiring. Next, for example, each power device 7 is placed on the base portion 58 via the plate solder 84.
4 is set. And case 52 is carried in on heater 85, for example, 250-4.
Heat at 00 ° C. Due to this heating, the heat transmitted to the metal base 58 is transferred to the sheet solder 84.
And the sheet solder 84 is melted. Thereby, the power device 74 is joined to the base portion 58 of the case 52. In FIG. 10B and below, the sheet solder 84 used for joining is omitted.

Next, with the case 52 placed on the heater 85, as shown in FIG. 10B, for example, the metal block 83 is set on the surface 741 of each power device 74 via the sheet solder 86. Then, the case 52 is heated at 250-400 degreeC, for example. This heating
The heat transferred to the metal base 58 is transferred to the plate solder 86 through the power device 74, and the plate solder 86 is melted. Thereby, the metal block 83 is joined to the power device 74. In FIG. 10C and below, the sheet solder 86 used for joining is omitted.

Next, as shown in FIG. 10C, the source terminal 54 is singly placed on the heater 85, and the preliminary solder 87 is applied on the source terminal 54. Next, the metal block 83 is positioned with respect to the preliminary solder 87 with the case 52 turned upside down, and the metal block 83 and the preliminary solder are brought into contact with each other.
Then, the metal block 83 and the source terminal 54 are joined by the heating of the heater 85 as shown in FIG. 10D.

Next, as shown in FIG. 10E, the top plate 53 is positioned so that the concave portion of the top plate 53 is aligned with the peripheral portion of the source terminal 54, and the connecting portion 66 of the top plate 53 is relative to the frame portion 59. Slide the top plate 53 until it contacts the source terminal 54. As a result, the device area 61 is closed.
As described above, according to the power module 51, the power device 74 and the source terminal 54 are connected.
A metal block 83 having a diameter larger than that of the wire is used as a wiring member for connecting the two.
Thereby, the wiring (metal block 83) can be joined to the power device 74 in a large area. Therefore, the occurrence of current concentration at the junction between the wiring (metal block 83) and the power device 74 can be suppressed. As a result, the current can be leveled. Furthermore, since the heat generated in the power device 74 can be efficiently dissipated by the metal block 83 and the plate-like source terminal 54, the heat dissipation effect can be improved.

Further, when the external terminal is a plate terminal provided along the top surface of the top plate 53 as in this embodiment, when the source terminal 54 receives an impact or the like from the outside, the impact is applied to the metal block 83. To the power device 74, and as a result, the device may be destroyed.
Therefore, in this embodiment, each of the arm portion 65 and the connecting portion 66 of the top plate 53 is a second one.
Portions 68 and 71 support the source terminal 54 from the back side. Thereby, even when the source terminal 54 receives an impact or the like, the impact can be reduced by the arm portion 65 and the connecting portion 66. As a result, the impact can be prevented from being transmitted to the power device 74 at all, or the impact transmitted to the power device 74 can be reduced. Therefore, destruction of the power device 74 due to impact can be prevented.

The top plate 53 is supported so as to be slidable with respect to the frame portion 59 and can be separated from the frame portion 59. Therefore, when the power module 51 is manufactured, the power device 74 can be first arranged in the device region 61 and the metal block 83 can be joined to the power device 74 in a state where the frame portion 59 and the top plate 53 are separated. Therefore, workability is good. In addition, the end of the top plate 53 opposite to the direction pulled out by the slide is an open end. Therefore, even after the top plate 53 is fixed to the frame portion 59, the device region 61 can be exposed by pulling out the top plate 53 without removing the connection between the metal block 83 and the source terminal 54. As a result, maintenance inside the case 52 can be easily performed.

Further, the peripheral edge portion along the long side of the source terminal 54 is fitted into a recess 69 defined by the first portion 67 of the arm portion 65 and the second portion 68 of the arm portion 65. Therefore, when the top plate 53 is slid along the frame portion 59, the source terminal 54 can be used as a guide member for guiding the top plate 53. Therefore, the top plate 53 can be easily positioned.

Further, the peripheral edge portion along the short side (the opposite side orthogonal to the sliding direction) of the source terminal 54 fits into the recess 72 defined by the first portion 70 of the connecting portion 66 and the second portion 71 of the connecting portion 66. ing. Therefore, when the top plate 53 is slid along the frame portion 59, the peripheral portion of the source terminal 54 is brought into contact with the first portion 70 of the connecting portion 66 of the top plate 53, thereby sliding the top plate 53. Can be stopped. That is, the plate terminal can also be used as a stopper member for stopping the sliding of the top plate 53. Therefore, the top plate 53 can be positioned more easily.

Further, since the back surface 742 of the power device 74 is directly joined to the metal base portion 58, electrical contact with the back surface 742 (drain side) of the power device 74 is
It can be taken using the case 52 of the power module 51.
Further, as in this embodiment, a metal block 83 having a high heat dissipation effect is replaced with a power device 74.
10A and 10B, for example, a method of heating the source terminal 54 with the heater 85 in a state where the plate solder is sandwiched between the metal block 83 and the source terminal 54 as in the process of FIGS. 10A and 10B. Then, the heat may be dissipated through the metal block 83 having a high heat dissipation effect. As a result, the preliminarily sandwiched sheet solder does not melt well, and there is a risk of poor bonding between the metal block 83 and the source terminal 54.

Therefore, in this embodiment, as shown in FIG. 10C, preliminary solder 87 is applied in advance to the source terminal 54, and the metal block 83 is brought into contact with and joined to the portion where the preliminary solder 87 is applied. Thereby, the metal block 83 and the source terminal 54 can be favorably joined. That is, the power module 51 can be manufactured easily and with high quality.
According to such a method, for example, as described in the above-described embodiment, even if the height difference h as shown in FIG. By applying 87, the height difference h can be supplemented by the preliminary solder 87. As a result, the plate-like source terminals 54 can be reliably bonded together to the plurality of metal blocks 83.

As mentioned above, although embodiment of this invention was described, this invention can also be implemented with another form.
For example, like the power module 101 shown in FIGS. 11 and 12, the metal block 24 may have a tapered shape whose cross-sectional area widens from the back surface 242 toward the front surface 241.
The material of the metal blocks 24 and 83 may be a metal material such as Cu, Al, or Fe.

In addition, various design changes can be made within the scope of matters described in the claims.

DESCRIPTION OF SYMBOLS 1 Power module 2 Case 3 Top plate 4 Source terminal 8 Base part 9 Frame part 14 Opening 15 Through-hole 16 Device area 18 Power device 24 Metal block 25 Recess 26 Bottom wall 51 Power module 52 Case 53 Top plate 54 Source terminal 58 Base part 59 Frame part 61 Device region 65 Arm part 66 Connection part 67 First part (of the arm part) 68 Second part of the (arm part) 69 Recess part 70 (of the arm part) First part 71 (of the connection part) 71 (Connection part) Second part 72 Recess 74 (Connecting part) 74 Power device 83 Metal block 101 Power module 181 (Power device) Surface 182 (Power device) Back surface 241 (Metal block) Surface 242 (Metal block) Back surface 741 Surface 742 (power device) Back surface 831 (Metal block) Front surface 832 (Metal block) Back surface Tr Transistor element Di Diode element

Claims (16)

A base member;
A semiconductor power device having a front surface and a back surface, the back surface being bonded to the base member;
Having a front surface and a back surface, the back surface is bonded to the surface of the semiconductor power device;
Rising from the surface of the semiconductor power device in a direction away from the base member;
A metal block used as a wiring member for the semiconductor power device;
A semiconductor power module comprising: an external terminal joined to the surface of the metal block and for supplying power to the semiconductor power device through the metal block. A case having a base portion having a device region in which the semiconductor power device is disposed, and a frame portion fixed to the base portion and surrounding the device region;
A resin top plate fixed to the frame portion of the case and facing the device region;
The external terminal includes a plate terminal provided along the top plate,
The semiconductor power module according to claim 1, wherein the top plate includes a support portion that overlaps the plate terminal in a plan view and supports the plate terminal from the back surface side thereof. In the top plate, an opening smaller than the planar area of the plate terminal is formed in a region facing the plate terminal,
The metal block is joined to the plate terminal through the opening,
The semiconductor power module according to claim 2, wherein the support portion of the top plate includes a peripheral portion of the opening that surrounds the metal block in the top plate. The semiconductor power module according to claim 2, wherein the top plate is a member provided so as to be separable from the frame portion. The top plate has an open end at a position on one side with respect to the plate terminal, and is formed in a U shape in a plan view having a closed end at a position opposite to the open end with respect to the plate terminal,
The closed end is supported by the frame portion so as to be slidable in a sliding direction along a direction away from the plate terminal,
The metal block is joined to the plate terminal in a region surrounded by the top plate between the open end and the closed end,
The semiconductor power module according to claim 2, wherein the support portion of the top plate includes an edge portion of the region of the top plate. The plate terminal includes a pair of first opposite sides extending along the sliding direction and the first
It is formed in a square shape in plan view having a pair of second opposite sides orthogonal to the opposite sides,
The top plate includes a pair of arm portions along the first opposite side and a connecting portion that connects the sliding direction one sides of the pair of arm portions, and the arm portion and the connecting portion allow the plate terminal to It is provided to surround the three surroundings,
The pair of arm portions respectively contact a peripheral portion of the plate terminal from a lateral outer side perpendicular to the sliding direction, and a lower end of the first portion along the back surface of the plate terminal. And has a second part that overhangs,
The said peripheral part along the said 1st opposite side of the said plate terminal is fitted in the recessed part divided by the said 1st part of the said arm part, and the said 2nd part of the said arm part. Semiconductor power module. The connecting portion has a first portion that comes into contact with the peripheral edge of the plate terminal from the outside in the sliding direction, and a second portion that projects from the lower end of the first portion along the back surface of the plate terminal. And
The said peripheral part along the said 2nd opposite side of the said plate terminal is fitted in the recessed part divided by the said 1st part of the said connection part, and the said 2nd part of the said connection part. Semiconductor power module. The base part and the frame part are both made of metal,
The base portion also serves as the base member that supports the semiconductor power device,
The semiconductor power module according to any one of claims 2 to 7, wherein the frame portion also serves as a second external terminal for supplying power to the semiconductor power device via the base portion. The semiconductor power module according to claim 1, wherein the semiconductor power device is a device using a SiC semiconductor. The semiconductor power module according to claim 9, wherein the metal block is made of Cu or an alloy material containing Cu. The semiconductor power module according to claim 1, wherein the metal block has a rectangular parallelepiped shape. The semiconductor power module according to any one of claims 1 to 10, wherein the metal block has a tapered shape in which a cross-sectional area increases from the back surface to the front surface. A plurality of the semiconductor power devices are provided,
The semiconductor power module according to claim 1, wherein the external terminals are collectively bonded to a metal block bonded to each of the semiconductor power devices. The semiconductor power module according to any one of claims 1 to 13, wherein the top plate is formed with a through hole penetrating in a thickness direction in a region outside the region overlapping the plate terminal in plan view. Bonding the back surface of the semiconductor power device having a front surface and a back surface to the base member;
After joining the base member and the semiconductor power device, having a front surface and a back surface, and joining the back surface of the metal block used as a wiring member for the semiconductor power device to the surface of the semiconductor device;
A step of pre-soldering the external terminals for supplying power to the semiconductor power device;
The metal block is brought into contact with the portion where the preliminary solder is applied in the external terminal,
The manufacturing method of a semiconductor power module including the process of joining the said external terminal and the said metal block by heating the said external terminal. The external terminal is a flat plate terminal,
The method of manufacturing a semiconductor power module according to claim 15, wherein the step of performing preliminary soldering includes a step of depositing a predetermined amount or more of solder on the plate terminal.

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