JP6233151B2 - Modules that use overlapping blocks - Google Patents

Description

  The present specification discloses a module including a semiconductor device, an insulating substrate, an overlapping block, a cooler, and the like.

  A technique for mounting a semiconductor device on an insulating substrate is known. Some semiconductor devices require cooling because they generate heat when operated. A module is known in which a semiconductor device that requires cooling is mounted on the surface of an insulating substrate, and a cooler is disposed on the back side of the insulating substrate.

  Generally, the thermal expansion coefficient of the insulating substrate and the thermal expansion coefficient of the cooler are different. When the insulating substrate and the cooler are directly fixed, thermal stress acts on the insulating substrate and / or the cooler by repeating the state in which the semiconductor device operates to generate heat and the state in which the semiconductor device is cooled after finishing the operation. The thermal stress impairs the long-term reliability of the module.

Therefore, a technique has been proposed in which a member that absorbs the difference in thermal expansion coefficient between the insulating substrate and the cooler is interposed. This member includes (1) does not hinder heat transfer between the insulating substrate and the cooler, and (2) is flexible in the direction along the back surface of the insulating substrate (otherwise, heat between the insulating substrate and the cooler is not flexible). The characteristic that the difference in expansion coefficient cannot be absorbed) is required.
Patent Documents 1 to 3 disclose a member interposed between an object to be cooled and an object to be cooled.

JP 2005-347616 A JP 2011-199202 A JP 2006-294699 A

  It is difficult to achieve the characteristics (1) and (2). Patent Document 1 discloses a member manufactured by impregnating a molten metal around a carbon fiber cloth. This member has good heat conductivity but lacks flexibility. Patent Document 2 discloses a member combining graphite foil. This member also has good heat conductivity but lacks flexibility. Patent Document 3 discloses a metal member in which deformation spaces are distributed and arranged. Although this member is deformed flexibly using the deformation space, the deformation space reduces heat transfer.

The present applicant does not disturb the heat transfer between the insulating substrate and the cooler (hereinafter referred to as low thermal resistance) and has the property of flexibly deforming along the back surface of the insulating substrate (hereinafter referred to as high stress relaxation property). The member which had it was developed and a patent application was filed (Japanese Patent Application No. 2013-256237). Details of the members are disclosed in the specification and drawings of the above patent application. This patent application has not been published yet and does not fall under the publicly known technology.
The present inventors have found that a module with high long-term reliability can be realized by utilizing the member according to the above patent application, and have created the following module.

The module disclosed in this specification includes a semiconductor device, an insulating substrate, an overlapping block, a cooler, and the like.
The semiconductor device is mounted on the surface of the insulating substrate. A semiconductor device generates heat when it operates and needs to be cooled. The overlapping block is interposed between the back surface of the insulating substrate and the cooler. The overlapping block is composed of graphite foil and metal foil. The graphite foil and the metal foil are arranged in such a direction that the normal line standing on the back surface of the insulating substrate extends along the contact surface of the graphite foil and the metal foil. Graphite foil and metal foil are superposed. However, the graphite foil and the metal foil are simply overlapped, and they are not joined. For example, graphite foil and metal foil can slide along the contact surface. Alternatively, the superposition state of the graphite foil and the metal foil can be changed, and can be changed to the superposition state in which the adhesion force between the two is increased, or can be changed to the superposition state in which the adhesion force between the two is reduced. In the present specification, a state in which the graphite foil and the metal foil are simply overlapped and no further restraint relationship is taken between them is referred to as a non-bonded state. When the overlapping block used in this technique is observed from the normal direction, the contact surfaces of the graphite foil and the metal foil are distributed over the entire area of the overlapping block. For example, by wrapping a long multilayer foil with a long graphite foil and a long metal foil overlapped, the contact surface between the graphite foil and the metal foil is spread over the entire area from the inside to the outside in the radial direction. Will exist. In such a case, the contact surface is distributed over the entire area of the overlapping block.
In order to maintain the state in which the long multilayer foil is wound in multiple layers, the end of the foil located on the outermost periphery may be maintained by being welded or the like. Or it may maintain in the wound state by restraining an outer periphery with metal foil etc. In this case, the outermost foil is flexibly deformed. Since the outermost foil is flexibly deformed, the graphite foil and the metal foil can slide along the contact surface. Alternatively, it can be changed to an overlapped state in which the adhesion between the graphite foil and the metal foil is increased, or can be changed to an overlapped state in which the adhesion is reduced. The foil that holds the wound state on the outermost periphery is maintained in a state where the graphite foil and the metal foil are overlapped, and is not restrained any more. The foil that is in the outermost periphery and maintains the rolled state maintains a state in which the graphite foil and the metal foil are superposed in a non-bonded state.
The same applies to the foil surrounding the outer periphery of the laminated body in order of the first graphite foil, the first metal foil, the second graphite foil, the second metal foil, the third graphite foil, the third metal foil, etc. Yes, as long as the foil surrounding the outer periphery is flexibly deformed, the foil simply maintains the graphite foil and the metal foil in a superposed state, and maintains the graphite foil and the metal foil in a non-bonded state.

When the above overlapping block is interposed between the insulating substrate and the cooler, the following phenomenon is obtained. (1) The graphite foil continuously extends from the insulating substrate side toward the cooler side. The graphite foil has a very low thermal resistance in the direction along the development surface. Even when the overlapping block is interposed, the thermal resistance between the insulating substrate and the cooler can be maintained at a low value. (2) The overlapping block is deformed flexibly. The graphite foil and the metal foil are in a non-bonded state, and are deformed flexibly so as to slide on each other, overlap strongly, or reduce the contact force. When the cooler expands and contracts with respect to the insulating substrate, the overlapping block flexibly deforms, so that excessive stress is not generated on the insulating substrate, and excessive stress is applied to the cooler. It does not occur. High stress relaxation.
The above overlapping block has a low thermal resistance and a high stress relaxation property. By using the above overlapping block, the long-term reliability of the module is improved.

In this specification, an xyz orthogonal coordinate system is used, and the normal line passing through the semiconductor device (the normal line standing on the back surface of the insulating substrate) is defined as the z-axis. In this case, it is preferable that the contact surface extending along the xz plane and the contact surface extending along the yz plane exist in the overlapping block.
If both a contact surface extending along the xz plane and a contact surface extending along the yz plane exist, both expansion and contraction in the x direction between the insulating substrate and the cooler can be expanded and contracted in the y direction. Is also flexible and easy to deform.

An overlapping block can be formed by winding a long multilayer foil obtained by superimposing a long graphite foil and a long metal foil around the z-axis in multiple layers. This overlapping block is easy to manufacture.
There can be various configurations for maintaining the rolled state (not to unwind). It is possible to maintain the wound state by welding the end of the outermost foil to the inner foil, or it is possible to maintain the wound state by wrapping the outer periphery with foil. In any case, the graphite foil and the metal foil can slide along the contact surface, the adhesion between the graphite foil and the metal foil can be increased, or the adhesion can be reduced. It is possible to overlap the metal foil.

In the case of an overlapped block in which long foils are wound in multiple layers, it may be preferable that graphite foils are densely present at positions on the inner side in the radial direction and graphite foils are sparsely present at positions on the outer side in the radial direction.
In that case, when the long multilayer foil before winding is observed in the longitudinal direction, a long multilayer film in which the number of metal foils superimposed on the graphite foil varies depending on the distance from the winding start end may be used.
For example, one metal foil is superimposed on the graphite foil at a distance from the beginning of winding to 1000 rotations, and two metal foils are superimposed at a distance from 1000 to 2000 rotations, and 2000 to 3000 rotations. If a long multilayer film in which three metal foils are stacked is used, the graphite foil is densely arranged at the center and the graphite foil is sparsely arranged at the periphery. An alignment block can be obtained.

  Depending on the semiconductor device, the amount of heat generated per unit area may be unevenly distributed. If the amount of heat generated per unit area is not uniform, a graphite block is densely arranged at a position where the heat value is large, and a laminated block where graphite foil is sparsely arranged at a position where the heat value is small is required It is said. An overlapping block in which the area where the graphite foil occupies in the unit area varies depending on the position is also useful.

When observed from the normal direction of the insulating substrate, the overlapping block may spread more widely than the semiconductor device. In order to utilize a wide spread block, the heat of a semiconductor device existing in a narrow area is transferred in a direction along the surface of the overlap block, and the spread block is spread more widely than the semiconductor device. It is preferable to conduct heat efficiently over a wide range.
Therefore, a module in which an insulating substrate side heat spreader is added between the insulating substrate and the overlapping block is meaningful. A heat spreader is formed with a graphite foil having an opening substantially matching the outer shape of the semiconductor device and extending along the surface of the overlapping block, and a metal foil covering the front and back of the graphite foil. Is added between the insulating substrate and the overlapping block, the heat of the high-temperature semiconductor device existing in a narrow area is transferred in the direction along the surface of the overlapping block, and the wide area of the overlapping block spreading widely Heat can be transferred efficiently. In addition, the thermal resistance of the path directly transferring heat from the insulating substrate to the cooler is not increased.

When observed from the normal direction of the insulating substrate, the cooler may spread more widely than the overlapping block. In order to utilize a cooler that is widely spread, it is preferable to interpose a cooler-side heat spreader between the overlapping block and the cooler.
In that case, the heat spreader on the cooler side is formed by a graphite foil that has an opening substantially matching the outer shape of the overlapping block and extends along the surface of the cooler, and a metal foil that covers the front and back of the graphite foil. Can be formed.

  “Foil” as used in the present specification refers to a material that has been thinned to such an extent that flexibility that can be easily bent by human power appears, and should be compared with a “plate” that does not easily bend. It is. What is called a film sheet is also a kind of “foil”.

FIG. 3 is an exploded perspective view of the basic configuration of the module according to the first embodiment. The top view of the overlapping block of 2nd Example. The top view of the overlapping block of 3rd Example. The top view of the overlapping block of 4th Example. The top view of the superposition block of 5th Example. The top view of the overlapping block of 6th Example. The top view of the overlapping block of 7th Example. The top view of the overlapping block of 8th Example. The top view of the overlapping block of 9th Example. (A) is the figure which looked at the elongate multilayer foil which forms the overlapping block of 10th Example, (b) is a top view in an inner peripheral part, (c) is a top view in an intermediate part (D) is a plan view of the outer periphery. The top view of the overlapping block of 11th Example. It is the figure which decomposed | disassembled the perspective view of the module of 2nd Example, and has also shown the internal structure of the heat spreader.

The features of the technology disclosed in this specification will be summarized below. The items described below have technical usefulness independently.
(First feature) Overlapping blocks are formed of graphite foil and aluminum foil. Aluminum foil is used for the metal foil.
(Second feature) A metal is disposed between the insulating substrate and the overlapping block, and the insulating substrate and the overlapping block are brazed.
(Third feature) The metal is placed between the overlapping block and the cooler, and the overlapping block and the cooler are brazed.
(Fourth feature) Graphite foils are densely arranged at positions corresponding to the center position of the semiconductor device, and graphite foils are sparsely arranged at positions corresponding to the peripheral position of the semiconductor device.

FIG. 1 is an exploded perspective view of a module 80 of the first embodiment in which a semiconductor device 10, an insulating substrate 20, an overlapping block 30, and a cooler 70 are sequentially stacked.
The semiconductor device 10 includes a front electrode and a back electrode, switches a large current, and generates heat when operated. If it is not cooled, the semiconductor device 10 will be overheated, so cooling is required.
A wiring layer 22 is formed on the surface of the insulating substrate 20. The back electrode of the semiconductor device 10 is soldered to the wiring layer 22. The semiconductor device 10 is mounted on the surface of the insulating substrate 20. A conductor (not shown) is bonded to the surface electrode of the semiconductor device 10, and a conductor (not shown) is also bonded to the wiring layer 22. The insulating substrate 20 is made of ceramic and has a smaller coefficient of thermal expansion than a metal cooler 70 described later.
The cooler 70 is made of a metal (aluminum) having a low thermal resistance, and a passage for the coolant is formed inside.
If the back surface of the insulating substrate 20 is soldered to the surface of the cooler 70, the thermal resistance between the two can be kept low, but a large thermal stress develops in the insulating substrate 20 and the cooler 70, causing the insulating substrate 20 to be warped or damaged. To do. In order to avoid this, the overlapping block 30 is interposed between the insulating substrate 20 and the cooler 70. The overlapping block 30 has a low thermal resistance so as not to increase the thermal resistance between the insulating substrate 20 and the cooler 70, and is deformed flexibly so that a large thermal stress is generated in the insulating substrate 20 and the cooler 70. To prevent.

  In the first embodiment of FIG. 1, the overlapping block 30 is formed by winding a long multilayer foil in which a long graphite foil 34 and a long metal foil 36 are overlapped around the core 32 in multiple layers. ing. The graphite foil 34 and the metal foil 36 are simply overlapped, and there is no further constraint relationship. Even when wrapping in multiple layers, there is no more restraining relationship than simply wrapping them so as to overlap each other. In order to maintain the wound shape, the end portion of the outermost metal foil 36 is welded to the metal foil 36 located inside the metal foil 36. The outermost peripheral end of the metal foil 36 extends longer than the outermost peripheral end of the graphite foil 34 so that the metal foil 36 is exposed inside the end of the outermost peripheral metal foil 36. In the drawing, the thicknesses of the graphite foil 34 and the metal foil 36 are displayed thicker than actual, and as a result, the number of turns is displayed smaller than actual. The same applies to FIG. An aluminum film can be used for the metal foil. When higher heat conductivity is required, it is preferable to use a copper foil.

  The front surface and the back surface of the insulating substrate 20 extend in parallel, and the normal line direction is taken as the z axis. The graphite foil 34 and the metal foil 36 are arranged so that the z-axis extends along the contact surface between the graphite foil 34 and the metal foil 36, and are wound around the z-axis. The overlapping block 30 is formed with a contact surface extending along the xz plane and a contact surface extending along the yz plane.

The surface of the overlapping block 30 is brazed to the back surface of the insulating substrate 20. The back surface of the overlapping block 30 is brazed to the surface of the cooler 70. In the step of forming the module 80, the surface of the overlapping block 30 is constrained by the insulating substrate 20, and the back surface of the overlapping block 30 is constrained by the cooler 70.
The superposition block 30 may be brazed after the front and back surfaces are covered with a metal foil, or may be brazed with the surface where the metal foil and the aluminum film are mixed exposed. Good.

  When the semiconductor device 10 operates, the semiconductor device 10 generates heat, and the insulating substrate 20 and the cooler 70 are heated. Although the insulating substrate 20 has a higher temperature than the cooler 70, the thermal expansion coefficient of the cooler 70 is much higher than the thermal expansion coefficient of the insulating substrate 20, and thus the cooler 70 has a higher thermal expansion coefficient than the insulating substrate 20. The direction expands relatively. In the illustrated case, the cooler 70 expands relative to the insulating substrate 20 in both the x direction and the y direction.

  The surface of the overlapping block 30 is constrained by the insulating substrate 20, and the back surface of the overlapping block 30 is constrained by the cooler 70. If the cooler 70 expands relatively larger than the insulating substrate 20 and the rear surface deforms relatively larger than the surface of the overlapping block 30, the insulating substrate 20. In addition, no great thermal stress is generated in the cooler 70.

  In the superposition block 30, only the graphite foil 34 and the metal foil 36 are superposed. If the graphite foil 34 and the metal foil 36 can slide along the contact surface, the adhesion force between them is increased. If it can be changed, it can also be changed to a state in which the adhesion between the two has been reduced. The overlapping block 30 can be flexibly deformed. When the cooler 70 expands and contracts with respect to the insulating substrate 20, the overlapping block 30 is flexibly deformed. Even if the cooler 70 expands and contracts with respect to the insulating substrate 20, no large thermal stress is generated in the insulating substrate 20, and no large thermal stress is generated in the cooler 70. Further, no large thermal stress is generated in the overlapping block 30 itself. The module 80 shown in FIG. 1 obtains long-term reliability by using the overlapping block 30 that has low thermal resistance and is sufficiently flexible.

  When the overlapping block 30 is formed, a rectangular column-shaped block is formed by wrapping a long multilayer foil in which a wide long graphite foil 34 and a wide long metal foil 36 are overlapped. It is formed and cut into a plurality of overlapping blocks 30 by cutting along the cross section.

In the following, various overlay blocks will be described. In the following description, only the differences will be described. Duplicate explanation is omitted.
(Second embodiment)
As shown in FIG. 2, the overlapping block 30a of the second embodiment is obtained by wrapping a long multilayer foil in which a long graphite foil 34a and a long metal foil 36a are overlapped in multiple layers. Is forming. Also in the overlapping block 30a of this embodiment, the normal line of the insulating substrate 20 extends along the contact surface between the graphite foil 34a and the metal foil 36a, and extends along the contact surface extending along the xz surface and the yz surface. It also has an extended contact surface.

(Third embodiment)
If the insulating substrate 20 is rectangular, the overlapping block 30a of the second embodiment can be rectangular. As shown in FIG. 3, the overlapping block 30b of the third embodiment is formed by cutting the overlapping block 30a of the second embodiment along four cutting lines 40b. If the overlapping block 30a of the second embodiment is brazed to the insulating substrate 20 and then cut, the overlapping block 30b of the third embodiment maintains the overlapping state.

(Fourth embodiment)
A press force can be applied to the outer periphery of the overlapping block 30a of the second embodiment to correct it to a rectangle. As shown in FIG. 4, the overlapping block of the fourth embodiment simultaneously applies pressing forces F1, F2, F3, and F4 from four directions orthogonal to the outer periphery of the overlapping block 30b of the second embodiment. Then, the overlapping block is deformed as indicated by arrows M1, M2, M3, and M4, and is corrected to a substantially rectangular shape.

(5th Example)
Since the overlapping block deforms flexibly, both the contact surface extending along the xz plane and the contact surface extending along the yz plane are not necessarily required. In the case of the overlapping block 30d of the fifth embodiment shown in FIG. 5, the contact surface extends along the xz surface, and the area of the contact surface extending along the yz surface is small. This overlapping block 30d also follows well not only the expansion / contraction in the y direction but also the expansion / contraction in the x direction. Both the y-direction embedding relaxation property and the x-direction embedding relaxation property are combined.
The overlapping block 30d in FIG. 5 is formed by laminating a long multilayer foil in which a long metal foil 36d is overlapped on both the front and back surfaces of a long graphite foil 34d while being folded. For the sake of clarity of illustration, the contact surfaces of the metal foils 36d are not shown. Reference numeral 42d is a metal foil surrounding the outer periphery of the stacked overlapping blocks while being folded back, and maintains the shape of the overlapping block 30d when no external force is applied. The metal foil 42d surrounding the outer periphery is sufficiently flexible and does not impair the flexibility of the overlapping block 30d.

(Sixth embodiment)
FIG. 6 shows an overlapping block 30e of the sixth embodiment. A long multilayer foil in which a long graphite foil 34e and a long metal foil 36e are superposed is wound in multiple layers so as to form a triangle. The six triangles thus obtained are combined as shown in the figure, and the outer periphery thereof is wrapped with the foil 42e, whereby the overlapping block 30e of the sixth embodiment is obtained.

  In the above embodiment, a long foil is used. Alternatively, a stacked block can be formed by laminating a large number of short foils. As shown in FIG. 7, the overlapping block 30f of the seventh embodiment forms a overlapping block 30f by laminating a plurality of short graphite foils 34f and short metal foils 36f alternately. Reference numeral 42f is a metal foil surrounding the outer periphery, and regulates the shape of the overlapping block 30f in a state where no external force acts. The metal foil 42f surrounding the outer periphery is sufficiently flexible and does not impair the flexibility of the overlapping block 30f.

  FIG. 8 shows an overlapping block 30g of the eighth embodiment, which is configured by combining two overlapping blocks 30f of the seventh embodiment. The upper overlapping block 30f1 is placed in a direction in which the contact surface is in the xz plane, and the lower overlapping block 30f2 is placed in a direction in which the contact surface is in the yz plane. The back surface of the overlapping block 30f1 and the surface of the overlapping block 30f2 can be brazed.

(Ninth embodiment)
FIG. 9 shows an overlapping block 30h of the ninth embodiment. Each of the graphite foil 34h and the metal foil 34h has a concentric circle. 42h is a foil surrounding the outer periphery. The necessary flexibility and heat transfer can be ensured even in the overlapping block 30h of the ninth embodiment.

(Tenth embodiment)
(A) of FIG. 10 has shown the elongate multilayer foil 35 before winding. When the long multilayer foil 35 is wound, the number of metal foils interposed between the graphite foil and the graphite foil changes as it is wound. FIG. 10 shows the compressed length direction. Actually, for example, one metal foil 36j1 is superimposed on the graphite foil 34j at a distance from the beginning of winding to 1000 rotations, and two metal foils 36j1 and 36j2 are overlapped at a distance from 1000 to 2000 rotations. The three metal foils 36j1, 36j2, 36j3 are overlapped at a distance of 2000 to 3000 revolutions. By using this long multilayer film 35, it is possible to obtain an overlapped block in which graphite foils are densely arranged in the central portion and graphite foils are sparsely arranged in the peripheral portion. (B) shows the superposition state in the vicinity of the center, (d) shows the superposition state in the vicinity of the periphery, and (c) shows the superposition state in the intermediate area. In many semiconductor devices 10, the heat generation amount is high near the center and the heat generation amount is low near the periphery. The superposition state shown in (b) is opposed to the vicinity of the center where the heat generation amount is large, and the superposition state shown in FIG. In addition, it is preferable that at least 10% of the metal foil occupies a position where graphite is densely present. When 10% of metal foil is mixed for each unit area, necessary mechanical strength can be ensured.

(Eleventh embodiment)
FIG. 11 shows an overlapping block used when two semiconductor devices having a higher calorific value at the center are mounted on an insulating substrate. Corresponding to the higher calorific value at the center, the distance a between the graphite foil and the graphite foil is narrow near the center, the distance c between the graphite foil and the graphite foil is wide near the periphery, and the distance between the graphite foil and the graphite foil in the middle area b is in the middle.
An overlapped block is formed by arranging two concentric bodies side by side so as to correspond to two semiconductor devices.

(Module of the second embodiment)
As shown in FIG. 12, in the module 80 a of the second embodiment, the cooler 70 is wider than the overlapping block 30 when observed from the normal direction of the insulating substrate 20. In order to utilize the cooler 70 that is widely spread, a cooler-side heat spreader 60 is interposed between the overlapping block 30 and the cooler 70.

The cooler-side heat spreader 60 is formed with an aperture 66 that substantially matches the outer shape of the overlapping block 30 and extends along the surface of the cooler 70, and covers the front and back of the graphite foil 64. The metal foils 62 and 68 are formed. The graphite foil 64 is placed in such a direction that the thermal conductivity in the direction along the xy plane becomes very high. The upper metal foil 62 is also provided with an opening 63 that substantially matches the outer shape of the overlapping block 30.
The overlapping block 30 passes through the opening 63 of the upper metal foil 62 and the opening 66 of the graphite foil 64 and is fixed to the upper surface of the lower metal foil 68. The outer shapes of the metal foils 62 and 68 are slightly larger than the outer shape of the graphite foil 64, and the metal foils 62 and 68 face each other without the graphite foil 64 interposed outside the outer shape of the graphite foil 64. The metal foils 62 and 68 are brazed at the opposing peripheral portions without the graphite foil 64 interposed therebetween, whereby the position of the graphite foil 64 in the xy plane is fixed.
The overlapping block 30 and the cooler 70 are brazed using the lower metal foil 68.

  The heat transferred to the graphite foil 34 located on the outer peripheral side of the overlapping block 30 is transferred to the graphite foil 64 and transferred to a wide area on the upper surface of the cooler 70. On the other hand, the heat transferred to the graphite foil 34 located on the inner peripheral side of the overlapping block 30 is transferred to the cooler 70 through the opening 66 without being interrupted by the graphite foil 64. The graphite foil 64 has a property that heat conductivity in a direction along the surface is good, but heat conductivity in a direction perpendicular to the surface is low. When the opening 66 is formed, it is possible to avoid a problem that the heat transfer property in the direction orthogonal to the surface is low.

  For example, a cross-shaped beam may be passed through the openings 63 and 66. In this case, the thermal resistance of the path that directly transfers heat from the center of the overlapping block 30 to the cooler 70 increases, but a heat transfer path that extends over a wide range of the cooler 70 via the graphite foil 64 is formed, and the semiconductor The substantial thermal resistance from the center of the device 10 to the cooler 70 may decrease. The apertures 63 and 66 are not necessarily complete apertures, and may be ones that pass beams as needed. When passing the beam, it is preferable to form a groove for receiving the beam on the lower surface of the overlapping block 30.

In the case of the module 80 a of FIG. 12, the overlapping block 30 is wider than the semiconductor device 10. In order to utilize the overlapping block 30 that is widely spread, the heat of the high-temperature semiconductor device 10 existing in a narrow range is transferred in a direction along the surface of the overlapping block 30 so that it is wider than the semiconductor device 10. It is preferable to efficiently transfer heat to a wide range of the overlapping block 30 that is spreading.
Therefore, in this module 80 a, the insulating substrate side heat spreader 50 is added between the insulating substrate 20 and the overlapping block 30. The insulating substrate side heat spreader 50 has the same structure as the cooler side heat spreader 60. Although not shown, the insulating substrate-side heat spreader 50 is formed with a graphite foil having an opening substantially matching the outer shape of the semiconductor device 10 and extending along the surface of the overlapping block 30, and the graphite foil. It is formed with the metal foil which coat | covers the front and back of this. When the heat spreader 50 is added between the insulating substrate 20 and the overlapping block 30, the heat of the high-temperature semiconductor device 10 existing in a narrow range is transferred in a direction along the surface of the overlapping block 30, and spreads widely. Heat can be efficiently transferred to a wide range of the overlapping block 30. In addition, the thermal resistance of the path for transferring heat directly from the insulating substrate 20 to the cooler 70 is not increased.
In the case of the insulating substrate side heat spreader 50 as well, as in the case of the cooler side heat spreader 60, a beam may be passed to the opening of the graphite foil.

Specific examples of the present invention have been described in detail above, but these are merely examples and do not limit the scope of the claims. The technology described in the claims includes various modifications and changes of the specific examples illustrated above.
The technical elements described in this specification or the drawings exhibit technical usefulness alone or in various combinations, and are not limited to the combinations described in the claims at the time of filing. In addition, the technology exemplified in this specification or the drawings can achieve a plurality of objects at the same time, and has technical usefulness by achieving one of the objects.

10: Semiconductor device 20: Insulating substrate 22: Wiring layer 30: Overlapping block 32: Core 34: Graphite foil 35: Long multilayer foil 36: Metal foil 38: Fixed part 40: Cutting line 42: Perimeter constraining foil 50: Insulation Substrate side heat spreader 60: cooler side heat spreader 62: metal foil 64: graphite foil 66: aperture 68: metal foil

Claims (7)

A module comprising a semiconductor device, an insulating substrate, an overlapping block and a cooler,
The semiconductor device is mounted on the surface of the insulating substrate,
The overlapping block is interposed between the back surface of the insulating substrate and the cooler, and is composed of a graphite foil and a metal foil, and a normal line standing on the back surface of the insulating substrate is the graphite foil and the Arranged in a direction extending along the contact surface of the metal foil, the graphite foil and the metal foil are overlapped in a non-bonded state, and when the overlapping block is observed from the normal direction, A module in which contact surfaces are distributed over the entire area of the overlapping block.   When the normal passing through the semiconductor device is the z axis of the xyz orthogonal coordinate system, the contact surface extending along the xz plane and the contact surface extending along the yz plane exist. The module according to claim 1.   3. The module according to claim 2, wherein a long multilayer foil obtained by superimposing the long graphite foil and the long metal foil is wound around the z-axis in multiple layers.   The module according to claim 3, wherein the number of the metal foils superimposed on the graphite foil changes when the long multilayer foil is observed in the longitudinal direction.   The observation area of the overlapped block from the normal direction is such that the existing area of the graphite foil occupying within a unit area varies depending on the position. Modules. An insulating substrate side heat spreader is interposed between the insulating substrate and the overlapping block,
The insulating substrate side heat spreader is formed of a graphite foil having an opening substantially matching the outer shape of the semiconductor device and extending along the back surface of the insulating substrate, and a metal foil covering the front and back of the graphite foil. The module according to claim 1, wherein the module is formed. A cooler side heat spreader is interposed between the overlapping block and the cooler,
The cooler-side heat spreader is formed with a graphite foil having an opening substantially matching the outer shape of the overlapping block and extending along the surface of the cooler, and a metal foil covering the front and back of the graphite foil The module according to claim 1, wherein the module is formed by the following.

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