WO2009098865A1

WO2009098865A1 - Heat spreader, and method for manufacturing the same

Info

Publication number: WO2009098865A1
Application number: PCT/JP2009/000414
Authority: WO
Inventors: Masahiro Omachi; Tomoyuki Sugiyama
Original assignee: A.L.M.T. Corp.
Priority date: 2008-02-06
Filing date: 2009-02-03
Publication date: 2009-08-13
Also published as: JPWO2009098865A1; JP4382154B2

Abstract

Provided are a heat spreader (1), which can grasp the position of a backing intuitively from the appearance thereof, and a manufacturing method which can manufacture the heat spreader at less steps while preventing the displacement of the backing. The heat spreader (1) is formed in a flat plate shape, in which a flat-shaped backing (2) is covered at its planar outer periphery with a frame (3) of a metal or an alloy and at its surface (4) and back (5) with coating layers (6 and 7) of a metal or an alloy, and in which at least one of a surface (11) and a back (12) has grooves (13 and 14) formed in the planar direction along the outer edge of the internal backing (2). The manufacturing method either fills a mixture (25) for the backing (2) in the region, which is enclosed by the frame (3) and by thin sheets (22 and 26) to be fitted in the ring of the frame (3) to form the coating layers (6 and 7), or fits the backing (2) in that region, and performs a compression-molding treatment. After this, the method performs a sintering treatment at the metal or alloy melting point or lower.

Description

Heat spreader and manufacturing method thereof

The present invention relates to a heat spreader that is preferably used for removing heat from an element that generates a large amount of heat during operation, such as a power semiconductor element, and a manufacturing method thereof.

In an element that generates a large amount of heat during operation, it is required to remove the heat as quickly as possible. This is because if the generated heat is not removed promptly, the element itself may overheat, causing malfunction (thermal runaway) or damage. As such an element, for example, a power semiconductor element such as an insulated gate bipolar transistor used in an inverter circuit for performing power conversion from direct current to alternating current when driving an induction motor in an electric vehicle, a hybrid vehicle, a railway vehicle, and the like, Examples thereof include an image display element such as a plasma display panel, a microprocessor unit for a computer, or a laser diode.

In recent years, with the progress of higher performance and higher output of the various devices, the element is made of silicon (Si), gallium arsenide (GaAs), The transition from indium-phosphorus (InP) elements to silicon carbide (SiC) elements and gallium nitride (GaN) elements has been studied. In that case, it becomes possible to raise the operable temperature of the element from around 120 ° C., such as a Si element, to around 200 ° C., such as a SiC element, and it is less likely to cause malfunction or damage due to overheating. It is considered possible.

However, it is still necessary to remove heat from these elements as quickly as possible. In order to quickly remove heat from the element and prevent malfunction and damage, for example, a flat plate heat spreader is generally used. That is, the element is mounted directly on one surface of the flat plate heat spreader or by soldering or the like via a ceramic substrate or the like. In addition, the other surface of the heat spreader is screwed in a state where the other surface of the heat spreader is brought into contact with the surface of a cooler, a heat sink, or a heat transfer member to the cooler (hereinafter sometimes referred to as “cooling member”). And fix. Then, heat from the element can be removed by quickly conducting heat to the cooling member via the heat sink.

Conventionally, the heat spreader has been integrally formed of a metal such as aluminum or copper, or an alloy. However, recently, the thermal expansion coefficient is close to the elements made of various materials described above or the ceramic substrate made of aluminum nitride (AlN), aluminum oxide (Al ₂ O ₃ ), silicon nitride (Si ₃ N ₄ ), or the like. In addition, the use of a heat spreader made of an aluminum-ceramic composite material having a thermal conductivity equivalent to that of a metal or alloy has been studied (see, for example, Patent Documents 1 to 3). This is because the thermal expansion coefficient of the element or the ceramic substrate and the heat spreader is made as close as possible, so that excessive stress is applied to the element based on the difference in thermal expansion coefficient when heat generation due to element operation and cooling after stopping are repeated. This is because it is considered that the element itself can be prevented from being damaged or the solder joint can be destroyed.

However, many of the composite materials are extremely hard and difficult to process, and are cut into a predetermined planar shape, or are provided with a blind hole or a counterbore for positioning at a predetermined position, or a screw hole for screwing. In order to form them, there is a problem that an expensive carbide tool such as a diamond tool must be used. In addition, the processing of the composite material has a problem that it takes time and labor compared to the processing of metal or alloy. Furthermore, since the composite material is brittle compared to metals and alloys, there is also a problem that it is easy to crack or start during processing.

In addition, in order to solder the element and ceramic substrate, etc., without causing voids that hinder heat conduction, the surface of the heat spreader is made of a nickel plating film having excellent wettability and affinity for the solder. It is preferable to coat. However, in the case of a heat spreader made of a composite material, the plating conditions differ greatly between the various materials constituting the composite material, for example, metals, alloys and ceramics, so that the surface of the heat spreader made of the composite material is directly stable and uniform. Another problem is that it is difficult to form a simple nickel plating film.

Therefore, in Patent Document 3 or Patent Documents 4 to 6, a coating layer made of the same or different metal or alloy as that forming the composite material is laminated on the front and back surfaces of the thin plate-like base material made of the composite material. A heat spreader having a laminated structure has been proposed.
In the heat spreader having the laminated structure, the surface or the back surface of the base material, which is the element mounting surface, is covered with a smooth coating layer made of a single metal or alloy, so that it is stable and uniform on the coating layer. A nickel plating film can be formed. Therefore, the element, the ceramic substrate, etc. can be satisfactorily soldered to the surface on which the nickel plating film is formed without generating voids or the like that hinder heat conduction. Further, the nickel plating film can be omitted by using a metal or an alloy constituting the coating layer having excellent wettability and affinity for solder.

However, the composite material constituting the base material sandwiched between the coating layers is still difficult to process. For this reason, it still takes time and labor to form screw holes and the like, and the problem that cracks and chips are likely to occur during processing cannot be solved. Therefore, a heat spreader has been proposed in which a frame body made of metal or alloy is provided surrounding the outer periphery in the surface direction of the base material, and screw holes are formed in the frame body portion (see Patent Document 7). .

According to the above-described configuration, the screw hole can be processed in a short time using a normal tool or the like, and can be prevented from being cracked or chipped in the base material made of the composite material. There are advantages.
JP-A-63-192801 JP-A-9-157773 JP 2004-91862 A JP 2002-235126 A JP 2003-253371 A WO2006 / 077755A1 JP 2003-204022 A

The heat spreader having the structure is manufactured by the method described in Patent Document 7, for example.
That is, the composite material is compression-molded or the like to produce a ceramic porous body (preform) as a base material. Also, a casting mold having a cavity having a predetermined three-dimensional shape of a heat spreader is prepared, and the previously produced porous body is set in the cavity. At this time, a space corresponding to the thickness of the frame body and the coating layer is provided between the porous body and the inner wall surface of the cavity. Next, in this state, a metal or alloy heated to a melting point or higher and melted is poured into the cavity. As a result, the poured metal or alloy is impregnated into the porous body to form a base material made of the composite material. At the same time, the space around the base material is filled with a metal or an alloy, and the frame body and the coating layer are formed integrally with the base material to manufacture the heat spreader.

However, it is difficult to accurately position the substrate made of the porous body in the heat spreader. When the metal or alloy is poured into the cavity, the porous body is displaced, and the substrate is often displaced by about 2 mm to 3 mm, particularly in the surface direction of the heat spreader. Moreover, in the manufactured heat spreader, as described above, the entire surface of the base material is covered with the coating layer made of metal or alloy and the frame, and the position of the base material cannot be grasped from the appearance. As a result, the following problems may occur.
(1) The base material shifted in the region requiring processing out of the frame protrudes and hinders processing.
(2) Soldered with the element or ceramic substrate protruding to the area where the base material does not exist (area consisting only of metal or alloy) on the front or back surface of the heat spreader. Excessive stress is applied to the element based on the difference in expansion coefficient, and the element itself is damaged or the solder joint is destroyed.

In order to prevent these problems from occurring, it is necessary to design the frame body and the base material in a larger size in consideration of the positional deviation. However, in that case, the heat spreader becomes large, and there is a problem that it cannot sufficiently meet the recent demands for downsizing and space saving of devices including the heat spreader.
For example, if the operation of specifying the position of the substrate by ultrasonic inspection or the like is performed on the total number of manufactured heat spreaders, the position of the substrate can be accurately grasped. However, there is a problem that the manufacturing process is time-consuming as the number of inspection processes increases, and the productivity of the heat spreader decreases.

An object of the present invention is to provide a novel heat spreader that can intuitively grasp the position of a base material from the appearance, and a manufacturing method for manufacturing the heat spreader in as few steps as possible while preventing the base material from being greatly displaced. Is to provide.

The present invention includes a flat base material, an annular frame made of a metal or an alloy, surrounding the outer periphery in the surface direction of the base material, and integrated with the base material, and a metal or alloy that is the same as or different from the frame body A flat plate-like heat spreader including a thin plate-like coating layer coated on the surface and the back surface of the base material, wherein at least one of the surface and the back surface of the heat spreader composed of the coating layer and the frame body, It is a heat spreader characterized by having a groove along the outer edge of the internal substrate in the surface direction of the front surface or the back surface.

According to the present invention, the position of the base material is determined from the appearance by the groove along the outer edge of the internal base material, which is provided on at least one of the front surface and the back surface of the heat spreader composed of the coating layer and the frame body. While intuitively grasping visually, it is possible to perform processing for forming a screw hole or the like, or to solder an element, a ceramic substrate, or the like. Therefore, it is not necessary to design the frame and the base material in consideration of the positional deviation of the base material, and the size of the equipment including the heat spreader is reduced and the size is reduced by minimizing the size of the frame body and the base material. It can contribute to space.

As the base material, it is preferable to remove heat from the element as quickly as possible while preventing various problems based on the difference in thermal expansion coefficient with the various elements and ceramic substrates described above. Any of various materials having a thermal expansion coefficient of 15 × 10 ⁻⁶ / K or less and a thermal conductivity of 150 W / m · K or more can be used.
As the substrate, for example,
(1) Aluminum-ceramic composite material,
(2) Copper-ceramic composite material,
(3) silicon-ceramic composite material,
(4) Copper-tungsten composite material,
(5) Copper-molybdenum composite material,
(6) Tungsten,
(7) molybdenum,
(8) Aluminum-silicon composite material, and
(9) There may be mentioned at least one selected from the group consisting of copper-diamond composite materials.

As the metal or alloy for forming the frame and the coating layer, various metals having excellent thermal conductivity equivalent to or higher than that of the base material in addition to excellent workability when processing to form screw holes and the like Any alloy can be used. Among them, a metal having a Vickers hardness Hv of 200 or less at a test force of 49.03 N (test load of 5 kgf), particularly aluminum, an aluminum alloy, copper, or a copper alloy is preferable. The frame and the covering layer may be formed of the same metal or alloy, or may be formed of different metals or alloys.

It is preferable that the distance between the surface of the heat spreader on the side where the element or ceramic substrate is soldered and the surface in contact with the cooling member on the opposite side, that is, the total thickness of the heat spreader is 1 mm or more. Thereby, the heat from the element can be transferred as efficiently as possible in the thickness direction of the heat spreader and the surface direction intersecting the thickness direction.
The thickness of the heat spreader is preferably 10 mm or less even within the above range. Thereby, it can contribute to size reduction, space saving, and weight reduction of the apparatus containing the said heat spreader.

The groove may be continuous or may be formed intermittently as long as the position of the base material embedded therein can be intuitively grasped from the appearance. However, in order to make the groove easy to visually recognize, it is preferable that the groove has a width of 0.02 mm or more and a depth of 0.01 mm or more. The width of the groove is preferably 0.5 mm or less even within the above range. Thereby, the precision of positioning of a base material can be improved. The depth is preferably 0.2 mm or less even within the above range. Thereby, it can prevent that the heat conduction of the surface direction of a heat spreader is inhibited.

The present invention is a manufacturing method for manufacturing the heat spreader of the present invention, wherein the substrate is made of an aluminum-ceramic composite material or an aluminum-silicon composite material, and the frame and the coating layer are made of aluminum or an aluminum alloy, The bottom surface of the press die including a lower punch having a bottom surface having a planar shape that matches the planar shape of the heat spreader and a die having an inner peripheral surface that surrounds the bottom surface and that has a shape that matches the shape of the side surface of the heat spreader. In the region surrounded by the inner peripheral surface, the annular frame body has a predetermined clearance at the fitting portion between the frame body and is fitted to the frame body to be one of the front surface or the back surface of the base material Setting a thin plate to be a coating layer for coating the frame, or setting a molded body having a shape obtained by integrating the frame and the thin plate; A step of setting an annular jig having the same planar shape as the frame on the frame or molded body, and a region surrounded by the thin plate and the frame and jig, or the molded body and the jig And a step of filling a mixture of aluminum or aluminum alloy powder and ceramic powder, or a mixture of aluminum or aluminum alloy powder and silicon powder, and a predetermined clearance at a fitting portion of the frame on the mixture. And compressing in the thickness direction of the heat spreader to obtain a compression-molded body in a state in which a thin plate that is fitted to the frame body and serves as a coating layer that covers the other of the front surface and the back surface of the base material is stacked. And a step of firing the compression-molded body at a temperature not higher than the melting point of aluminum or an aluminum alloy.

According to the production method of the present invention, in the firing step, a mixture of aluminum or aluminum alloy powder and ceramic powder or a mixture of aluminum or aluminum alloy powder and silicon powder in the compression molded body is sintered. While forming a base material, the frame body and thin plate which consist of aluminum or aluminum alloy can be integrated with the said base material, and a frame body and a coating layer can be formed.

Further, at that time, by setting the firing temperature to a temperature not higher than the melting point at which the aluminum or aluminum alloy melts and does not flow significantly, both of them can be determined based on the clearance set in the fitting portion between the frame and the thin plate. The groove can be accurately formed on the boundary line, that is, along the outer edge of the substrate. Therefore, the heat spreader having the groove can be efficiently manufactured with as few steps as possible.

Moreover, according to the manufacturing method, the mixture, which is filled and compression-molded later, is sintered at a temperature below the melting point in a ring of a frame having a predetermined size and shape set in advance in a press die. Therefore, there is no possibility that the base material is largely displaced in the heat spreader.
In the production method of the present invention, it is preferable that the compression-molded body is fired after being taken out of the press mold. According to such a configuration, the compression molded body taken out from the press die can be fired as it is or in a state where it is fitted in a simple (small heat capacity) mold frame for preventing the deformation of the mold, and thus it is necessary for firing. Energy and time can be saved.

In the above manufacturing method, the thickness of the thin plate that is the basis of the coating layer is preferably 0.05 mm or more. If the thickness is less than 0.05 mm, there is a possibility that a groove having a size that can be sufficiently visually recognized cannot be formed based on the mechanism described above. The thickness of the thin plate is preferably 1 mm or less even within the above range. As a result, the thickness of the coating layer to be formed is made as small as possible, and excessive stress is applied to the element based on the difference in thermal expansion coefficient between the aluminum or aluminum alloy forming the coating layer and the element or ceramic substrate. It is possible to prevent the element itself from being damaged or the solder joint from being destroyed.

Also, the clearance between the fitting portion of the frame and the thin plate is preferably 0.05 mm or more. If the clearance is less than 0.05 mm, there is a possibility that a groove having a size that can be sufficiently visually recognized cannot be formed based on the mechanism described above. The clearance is preferably 0.5 mm or less even within the above range. Thereby, it can prevent that the groove | channel formed is enlarged too much and the precision of the alignment of the base material by the said groove | channel falls.

In the production method, it is preferable to set the pressure during compression molding to 98 MPa or more and 686 MPa or less. When the pressure is less than 98 MPa, the strength of the compression-molded body is insufficient, and there is a possibility that the mold may be easily lost when it is taken out from the press die for firing or in the firing step after removal. Moreover, even if the pressure exceeds 686 MPa, there is a problem that the effect of increasing the strength of the compression molded body cannot be obtained any more, and a device such as a press die becomes too large for performing the high pressure compression molding.

The present invention is a manufacturing method for manufacturing the heat spreader of the present invention in which the frame body and the coating layer are made of copper or a copper alloy, and a step of producing a base material and a step of copper plating the surface of the base material A lower punch having a bottom surface having a planar shape that matches the planar shape of the heat spreader, and a die having an inner peripheral surface surrounding the bottom surface and having a shape that matches the shape of the side surface of the heat spreader. In the region surrounded by the bottom surface and the inner peripheral surface,
(a) The base material, an annular frame surrounding the base material, and a fitting portion between the frame body have a predetermined clearance, and the frame body is overlaid on the front surface and the back surface of the base material. Set two thin plates that are fitted together to form a coating layer, or
(b) The base material, a molded body having a shape in which the frame body and one thin plate are integrated, and a fitting portion between the frame body and a predetermined clearance, and a front surface or a back surface of the base material A step of setting the other thin plate that is fitted to the frame body to be a covering layer in a state of being overlaid on,
And heat-treating each part at a temperature below the melting point of copper or copper alloy while compression-molding each part in the thickness direction of the heat spreader.

According to the production method of the present invention, a frame and a thin plate made of copper or a copper alloy can be integrated with a base material in a step of heat treatment while compression molding, thereby forming a frame and a coating layer. Further, at that time, by setting the temperature of the heat treatment to a temperature not higher than the melting point at which copper or a copper alloy melts and does not flow greatly, both of the heat treatment are performed based on the clearance set in the fitting portion between the frame and the thin plate. The groove can be accurately formed on the boundary line, that is, along the outer edge of the substrate. Therefore, the heat spreader having the groove can be efficiently manufactured with as few steps as possible.

Moreover, according to the manufacturing method, since the heat spreader is manufactured by fitting the base material into the ring of the frame body having a predetermined size and shape set in the press die in advance, the base material is greatly increased in the heat spreader. There is no risk of displacement.
Also in the manufacturing method of the present invention, it is preferable that the thickness of the thin plate that is the basis of the coating layer is 0.05 mm or more. If the thickness is less than 0.05 mm, there is a possibility that a groove having a size that can be sufficiently visually recognized cannot be formed based on the mechanism described above. The thickness of the thin plate is preferably 1 mm or less even within the above range. Thereby, the thickness of the coating layer to be formed is made as small as possible, and excessive stress is applied to the element based on the difference in thermal expansion coefficient between the copper or copper alloy forming the coating layer and the element or the ceramic substrate. It is possible to prevent the element itself from being damaged or the solder joint from being destroyed.

According to the present invention, a novel heat spreader that can intuitively grasp the position of the base material from the appearance, and a manufacturing method for manufacturing the heat spreader in as few steps as possible while preventing the base material from being greatly displaced. Can be provided.

FIG. 1 is a partially cutaway plan view showing an example of an embodiment of a heat spreader of the present invention. FIG. 2 is a partially cutaway side view of the heat spreader of the example of FIG. FIG. 3 is an enlarged cross-sectional view of a part of FIG. FIG. 4 is a perspective view of the heat spreader in the example of FIG. FIG. 5 is a cross-sectional view showing one step of an example of the method for manufacturing the heat spreader of the present invention. FIG. 6 is a cross-sectional view showing the next step of the above example. FIG. 7 is a cross-sectional view showing the next step of the above example. FIG. 8 is a cross-sectional view showing the next step of the above example. FIG. 9 is a cross-sectional view showing the next step of the above example. FIG. 10 is a cross-sectional view showing one step of another example of the method for manufacturing a heat spreader of the present invention. FIG. 11 is a cross-sectional view showing a process of still another example of the method for manufacturing a heat spreader of the present invention. FIG. 12 is a cross-sectional view showing the next step of the above example. FIG. 13 is a cross-sectional view showing the next step of the above example. 14 is an optical micrograph showing a cut surface of the heat spreader manufactured in Example 1. FIG. FIG. 15 is an optical micrograph showing a cut surface of the heat spreader manufactured in Example 3.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Heat spreader 2 Base material 2a Outer edge 3 Frame body 4 Front surface 5

Back surface

6, 7 Coating layer 8 Screw hole 9 Notch 10 Bulging part 11 Surface 12

Back surface

13, 14

Groove

13a, 14a Deepest point 15 Bottom surface 16 Lower punch 17 Side surface (outer periphery) surface)
18 Inner peripheral surface 19 Die 20 Press die 21

Region

22, 26 Thin plate 23 Jig 24 Region 25 Mixture 26 Thin plate 27 Contact surface 28 Upper punch 29 Compression molded body 30 Molded body 31 Contact surface 32 Upper punch

<Heat spreader>
FIG. 1 is a partially cutaway plan view showing an example of an embodiment of a heat spreader of the present invention. FIG. 2 is a partially cutaway side view of the heat spreader of the example of FIG. FIG. 3 is an enlarged cross-sectional view of a part of FIG. FIG. 4 is a perspective view of the heat spreader in the example of FIG.
Referring to these drawings, a heat spreader 1 of this example includes a base plate 2 that is a rectangular flat plate as a whole, and an annular frame that surrounds the outer periphery in the surface direction of the base 2 and is integrated with the base 2. 3 and thin plate-like coating layers 6 and 7 coated on the front surface 4 and the back surface 5 of the substrate 2.

The base material 2 is provided with semicircular cutouts 9 for avoiding the screw holes 8 at three locations on the long side. The frame body 3 includes semicircular bulging portions 10 having the screw holes 8 at three locations on the long side corresponding to the notches 9. The frame 3 is integrated with the base material 2 in a state where the notch 9 is filled with the bulging portion 10. The frame 3 is made of a metal or an alloy, and the coating layers 6 and 7 are made of the same or different metal or alloy as the frame 3.

The front surface 11 and the back surface 12 of the heat spreader 1 constituted by the frame 3 and the coating layers 6 and 7 have

grooves

13 and 14 along the outer edge 2a of the inner base material 2 in the surface direction of the both

surfaces

11 and 12, respectively. is doing.
Referring to FIG. 3, in the present invention, “

grooves

13, 14” along the outer edge 2 a of the inner substrate 2 means that the outer edge 2 a and the deepest point 13 a in the cross-section in the width direction of the

grooves

13, 14. , 14a is a state in which the deviation G _{1 in} the surface direction is within ± 1 mm, particularly within ± 0.5 mm.

According to the heat spreader 1 of this example, since the both

surfaces

11 and 12 have the

grooves

13 and 14, respectively, the screw hole 8 Etc., and the element, the ceramic substrate and the like can be joined by soldering. Therefore, it is not necessary to design the frame body 3 and the base material 2 in consideration of the positional deviation of the base material 2, and the heat spreader 1 is included with the size of the frame body 3 and the base material 2 being kept to the minimum necessary. It is possible to contribute to downsizing and space saving of equipment.

The

grooves

13 and 14 may be continuous or may be formed intermittently as long as the position of the substrate 2 can be intuitively grasped from the appearance. However, in order to make the

grooves

13 and 14 visible as easily as possible, it is preferable that the

grooves

13 and 14 have a width of 0.02 mm or more and a depth of 0.01 mm or more. The widths of the

grooves

13 and 14 are preferably 0.5 mm or less, particularly 0.1 mm or more and 0.2 mm or less in order to increase the positioning accuracy of the substrate 2, and the depth is the surface of the heat spreader 1. In order to prevent the heat conduction in the direction from being hindered, it is preferably 0.2 mm or less, particularly preferably 0.1 mm or less.

The thermal expansion coefficient of the substrate 2 is preferably 15 × 10 ⁻⁶ / K or less. Thus, the difference in thermal expansion coefficient between the heat spreader 1 and a Si-based, GaAs-based, InP-based, SiC-based, GaN-based element, or a ceramic substrate such as AlN, Al ₂ O ₃ , Si ₃ N _4, etc. Can be reduced. Therefore, when the heat generation due to the operation of the element and the cooling after the stop are repeated, excessive stress is applied to the element based on the difference in the thermal expansion coefficient, and the element itself is damaged, or the solder joint is destroyed. Can be suppressed.

In the case of the base material 2 made of, for example, an aluminum-ceramic composite material, a silicon-ceramic composite material or the like, the thermal expansion coefficient of the base material 2 is preferably 2 × 10 ⁻⁶ / K or more even within the above range. The thermal expansion coefficient of the base material 2 made of the composite material can be adjusted by increasing or decreasing the ceramic content ratio. However, in order to make the thermal expansion coefficient less than 2 × 10 ⁻⁶ / K, the content of ceramic must be excessively increased, and the content of aluminum or the like as a binder is relatively decreased, This is because it becomes difficult to form the base material 2 having the composite structure substantially. Moreover, even if the base material 2 can be formed, the strength is insufficient, and there is a possibility that the base material 2 may not be practically used. For the base material 2 made of other materials, the lower limit of the thermal expansion coefficient is set according to the circumstances specific to each material.

Moreover, the thermal expansion coefficient of the base material 2 can be arbitrarily set within the above range depending on the thermal expansion coefficient of the element combined with the heat spreader 1, the ceramic substrate, and the cooling member. For example, a Si-based or SiC-based device having a thermal expansion coefficient of 3 × 10 ⁻⁶ / K is used as the device, and a thermal expansion coefficient of 17 × 10 ⁻⁶ / K or more is used as the cooling member, and 24 × 10 ⁻⁶ / K. In the case where a material having a temperature of about K or less is used, the thermal expansion coefficient of the substrate 2 is set to, for example, 6.5 × 10 ⁻⁶ / K or more and 15 × 10 ⁻⁶ / K or less. If it does so, all the difference of the thermal expansion coefficient between the said each part can be made small, and it can suppress that the various problems demonstrated previously generate | occur | produce.

Further, the heat spreader 1 is usually fixed to the cooling member by screwing or the like as described above. Therefore, some stress relaxation mechanism (such as making a screw hole a long hole) is provided between the heat spreader 1 and the cooling member to relieve the stress based on the difference in thermal expansion coefficient. May be adjusted so as to coincide with each other as much as possible so that the difference in coefficient of thermal expansion between the element and the ceramic substrate solder-bonded to the heat spreader 1 is as small as possible. For example, when the Si-based or SiC-based device is used as the device, the thermal expansion coefficient of the substrate 2 can be set to about 3 × 10 ⁻⁶ / K, which is the same as the device.

The thermal conductivity of the substrate 2 is preferably 150 W / m · K or more. As a result, the heat generated in the element can be conducted and removed to the cooling member as quickly as possible, so that it is possible to reliably prevent the element itself from overheating and malfunctioning or being damaged.
As the base material 2 that satisfies the ranges of the thermal expansion coefficient and the thermal conductivity, for example,
(1) Aluminum-ceramic composite material,
(2) Copper-ceramic composite material,
(3) silicon-ceramic composite material,
(4) Copper-tungsten composite material,
(5) Copper-molybdenum composite material,
(6) Tungsten,
(7) molybdenum,
(8) Aluminum-silicon composite material, and
(9) There may be mentioned at least one selected from the group consisting of copper-diamond composite materials.

Among these, the base material 2 made of the aluminum-ceramic composite material (1) includes, for example, those formed by any of the following forming methods.
(1-1) A mixture of aluminum or aluminum alloy powder and ceramic powder is compression-molded into the shape of the substrate 2 and then fired at a temperature not higher than the melting point of aluminum or aluminum alloy.

(1-2) The base material 2 obtained in the above (1-1) is compression-molded again while being heated to a temperature equal to or lower than the melting point of aluminum or aluminum alloy, thereby densifying the composite structure.
(1-3) A porous body (preform) made of ceramic formed in the shape of the substrate 2 is impregnated with molten aluminum or an aluminum alloy in, for example, a vacuum furnace.
In addition, simultaneously with manufacturing the heat spreader 1 by the manufacturing method of the present invention described later, the base material 2 formed in the heat spreader 1 corresponds to the one formed by the methods (1-1) and (1-2). .

As the powder of aluminum or aluminum alloy used in the method (1-1) or (1-2), for example, pure aluminum powder produced by an atomizing method or the like, or silicon (Si) at a ratio of 12% by mass or less. Examples thereof include aluminum-silicon alloy powder. Also, pure aluminum-based spreading materials such as alloy numbers A1050, A1070, and A1100 defined in Japanese Industrial Standard JIS H4000: 2006 “Aluminum and Aluminum Alloy Plates and Strips”, and aluminum-magnesium alloys such as A2014, A3004, and A5005 It is also possible to use a material such as a powder of an aluminum alloy for casting such as AC3A or AC4A.

The aluminum or aluminum alloy powder preferably has an average particle size of 30 μm or more and 60 μm or less. Thereby, aluminum or an aluminum alloy and ceramic can be distributed as finely and uniformly as possible in the base material 2, and the base material 2 can be formed without any bias in the distribution of both.
Examples of the ceramic powder include powder made of ceramic such as silicon carbide (SiC), silicon nitride (Si ₃ N ₄ ), and aluminum oxide (Al ₂ O ₃ ). The ceramic powder combined with the aluminum or aluminum alloy powder having the particle size range preferably has an average particle size of 30 μm or more and 60 μm or less. In particular, it is more preferable that the average particle diameter is equal to the aluminum or aluminum alloy powder to be combined. Thereby, aluminum or an aluminum alloy and ceramic can be distributed as finely and uniformly as possible in the base material 2, and the base material 2 can be formed without any bias in the distribution of both.

The mixing ratio of the aluminum or aluminum alloy powder and the ceramic powder can be arbitrarily set. As described above, the thermal expansion coefficient of the substrate 2 made of an aluminum-ceramic composite material can be adjusted by increasing or decreasing the ceramic content ratio. Therefore, what is necessary is just to adjust the mixing | blending ratio of both powder so that the thermal expansion coefficient of the said base material 2 may become arbitrary values of 15 * 10 < ^-6 > / K or less. Further, the ceramic porous body used in the forming method of (1-3) is formed by, for example, forming a mixture obtained by mixing the ceramic powder with a binder such as a resin into the shape of the base material 2 and then firing to remove the binder. In addition, the ceramic powder can be formed by sintering.

The base material 2 made of the copper-ceramic composite material (2) is the same as the aluminum-ceramic composite material (1) except that copper or a copper alloy is used instead of aluminum or an aluminum alloy. What was formed by the formation method etc. are mentioned.
(2-1) A mixture of copper or copper alloy powder and ceramic powder is compression-molded into the shape of the substrate 2 and then fired at a temperature below the melting point of copper or copper alloy.

(2-2) The base material 2 obtained in (2-1) is compression-molded again while being heated to a temperature equal to or lower than the melting point of copper or a copper alloy, thereby densifying the composite structure.
(2-3) The porous body made of ceramic formed in the shape of the substrate 2 is impregnated with molten copper or a copper alloy, for example, in a vacuum furnace.
Among these, as the powder of copper or copper alloy used in the forming method of (2-1) and (2-2), for example, pure copper powder produced by an atomizing method or the like, Japanese Industrial Standard JIS H3100: 2006 “copper and copper Examples thereof include powders such as alloy numbers C1020 “oxygen-free copper” and C1100 “tough pitch copper” defined in “Alloy plates and strips”. Also, the ceramic porous body used in the forming method of (2-3) is formed by mixing a ceramic powder with a binder such as a resin into a shape of the base material 2 and then firing the binder as described above. The ceramic powder can be formed by, for example, sintering the ceramic powder.

As the base material 2 made of the silicon-ceramic composite material of (3), those formed in the same manner as the aluminum-ceramic composite material of (1) above, except that silicon is used instead of aluminum or aluminum alloy, etc. It is done.
Examples of the substrate 2 made of the copper-tungsten composite material (4) include those formed by the following forming method.

(4-1) A mixture of copper or copper alloy powder and tungsten powder is compression-molded into the shape of the substrate 2 and then fired at a temperature equal to or higher than the melting point of copper or copper alloy.
(4-2) The porous body made of tungsten formed in the shape of the substrate 2 is impregnated with molten copper or a copper alloy in a vacuum furnace, for example.
The tungsten porous body used in the forming method of (4-2) is a ceramic in which, for example, a mixture in which tungsten powder is mixed with a binder such as a resin is formed into the shape of the base material 2 and then fired to remove the binder. It can be formed by sintering powder. The method of forming (4-2) is detailed in, for example, Japanese Patent Application Laid-Open No. 59-21032.

Examples of the substrate 2 made of the copper-molybdenum composite material (5) include those formed in the same manner as the copper-tungsten composite material (4) except that molybdenum is used instead of tungsten. Among these, the formation method for forming the copper-molybdenum composite material in the same manner as the formation method of (4-2) is described in detail in JP-A-59-21032.
Examples of the base material 2 made of tungsten of (6) include those in which the tungsten is formed into the shape of the base material 2 by an arbitrary forming method. Examples of the base material 2 made of molybdenum of (7) include those obtained by forming the molybdenum into the shape of the base material 2 by an arbitrary forming method.

Examples of the base material 2 made of the aluminum-silicon composite material of (8) include those formed in the same manner as the aluminum-ceramic composite material of (1) except that silicon powder is used instead of ceramic powder. . At the same time when the heat spreader 1 is manufactured by the manufacturing method of the present invention to be described later, the base material 2 formed in the heat spreader 1 is the same as the method (1-1) (1-2) using the silicon powder. It corresponds to what was formed. Furthermore, examples of the base material 2 made of the copper-diamond composite material (9) include those formed by the forming method described in JP-A No. 2004-175626.

The metal or alloy forming the frame 3 and the coating layers 6 and 7 is excellent in workability when processing the screw holes 8 and the like, and has various heat conductivities that are equal to or higher than that of the substrate 2. Any of these metals or alloys can be used. Among them, a metal having a Vickers hardness Hv of 200 or less at a test force of 49.03 N (test load of 5 kgf), particularly aluminum, an aluminum alloy, copper, a copper alloy, or the like can be given. The frame 3 and the coating layers 6 and 7 may be formed of the same metal or alloy, or may be formed of different metals or alloys.

For example, when the frame 3 is formed of aluminum or an aluminum alloy, the aluminum or aluminum alloy is preferably alloy numbers A1050, A2014, A3004, A5005, etc. defined in the above JIS H4000: 2006. The frame 3 made of aluminum or an aluminum alloy is formed into a predetermined three-dimensional shape having the bulging portion 10 shown in FIGS. 1 to 4 or the bulging portion 10 of the manufactured heat spreader 1. The processability for forming the screw hole 8 is excellent.

On the other hand, when the coating layers 6 and 7 are made of aluminum or an aluminum alloy, the aluminum or aluminum alloy may be a pure aluminum-based wrought material such as alloy numbers A1050, A1070, or A1100, or a casting material such as AC3A or AC4A. Alloys are preferred. These aluminum or aluminum alloys are excellent in workability and the like for finishing the thickness of the thin plate on which the coating layers 6 and 7 are based as uniform as possible.

When the frame 3 and the coating layers 6 and 7 are both formed of copper or a copper alloy, the copper or copper alloy is alloy number C1020 “oxygen-free copper” defined in the above-mentioned JIS H3100: 2006. C1100 “tough pitch copper” or the like is preferable. These copper or copper alloys have the workability for forming the frame 3 in a predetermined three-dimensional shape, as described above, and the workability for forming the screw holes 8 in the bulging portion 10 of the manufactured heat spreader 1. Alternatively, it is excellent in workability and the like for finishing the thickness of the thin plate as the basis of the coating layers 6 and 7 as uniform as possible.

<Method for manufacturing heat spreader (part 1)>
Of the heat spreader 1 of the present invention, the substrate 2 is made of the aluminum-ceramic composite material (1) or the aluminum-silicon composite material (8), and the frame 3 and the covering layers 6 and 7 are both aluminum or aluminum. What consists of an alloy can be manufactured with the manufacturing method of this invention demonstrated below. 5 to 9 are cross-sectional views showing respective steps of an example of the manufacturing method.

With reference to FIGS. 1 to 5, in the manufacturing method of this example, first, a lower punch 16 having a bottom surface 15 having a planar shape that matches the planar shape of the back surface 12 of the heat spreader 1 to be manufactured, and the bottom surface 15 are formed. A press die 20 is prepared that includes a die 19 having an inner peripheral surface 18 that is formed to coincide with the shape of the side surface 17 of the heat spreader 1 that is enclosed. In the example shown in the figure, the lower punch 16 and the die 19 are formed separately. However, for simplification, both are formed integrally, or the lower opening of the die 19 is replaced with an anvil instead of the lower punch 16. You can close it with

Next, in the area 21 surrounded by the bottom surface 15 and the inner peripheral surface 18 of the press die 20, the annular frame body 3 is fitted into the ring of the frame body 3 and the back surface 5 of the substrate 2. And the thin plate 22 to be the coating layer 7 covering the substrate.
Next, referring to FIGS. 6 and 7, an annular jig 23 having the same planar shape as the frame 3 is set on the previously set frame 3, and the thin plate 22 and the frame 3 are cured. A region 25 surrounded by the tool 23 is filled with a mixture 25 of aluminum or aluminum alloy powder and ceramic powder or silicon powder, which is the basis of the substrate 2. Then, a thin plate 26 to be a coating layer 6 that covers the surface 4 of the substrate 2 is overlaid on the mixture 25. The filling amount of the mixture 25 depends on the density and particle size of the ceramic powder and silicon powder constituting the mixture 25, the particle size of the powder of aluminum or aluminum alloy, the blending ratio of the two components, the density of the base material 2 to be formed, etc. It can be set as desired.

Next, referring to FIG. 8 and FIG. 9, an upper punch 28 in which the planar shape of the abutting surface 27 coincides with the planar shape of the thin plate 26 is abutted on the thin plate 26 stacked on the mixture 25. The upper punch 28 is pushed in the direction of the lower punch 16 and compression molded in the thickness direction to obtain a compression molded body 29, and then the compression molded body 29 is fired at a temperature not higher than the melting point of aluminum or aluminum alloy. Then, the base material 2 is formed by sintering the mixture 25 in the compression molded body 29. In addition, the frame 3 is integrated with the base material 2, and the

thin plates

22 and 26 are integrated with the base material 2 to form the covering layers 6 and 7, whereby the heat spreader 1 shown in FIGS. 1 to 4 is manufactured. The

The compression-molded body 29 may be fired by heating means (not shown) together with the press die 20 while maintaining the compression state of FIG. 9 by a so-called hot press molding method. However, the press die 20 is large as a whole because an excessive pressure of about 98 MPa or more is applied during compression molding, and the heat capacity is necessarily large. Therefore, when the hot press molding method is adopted, the compression molded body 29 must be continuously heated together with the press die 20 having a large heat capacity for the time required for firing (usually 0.5 hours or more). The energy and time required to manufacture one heat spreader 1 increases.

For this reason, in the present invention, for example, the compression molded body 29 compression-molded at room temperature is not shown, but is taken out from the press mold 20 as it is, or a simple (small heat capacity) mold frame for preventing the collapse of the mold. It is preferable to fire it by fitting it into the plate. Thereby, the energy and time required for firing can be reduced, and the productivity of the heat spreader 1 can be improved.
The firing temperature may be equal to or lower than the melting point of aluminum or aluminum alloy. However, the aluminum or aluminum alloy powder forming the base material 2 and the ceramic powder or the silicon powder are bonded as well as possible, and the frame 3 and the

thin plates

22 and 26 are integrated with the base material 2 as firmly as possible. In order to produce the heat spreader 1 as efficiently as possible, the firing temperature is preferably 550 ° C. or higher and 650 ° C. or lower. For the same reason, the firing time is preferably 0.5 hours or more and 2 hours or less.

The pressure during compression molding is preferably 98 MPa or more and 686 MPa or less. When the pressure is less than 98 MPa, the strength of the compression-molded body 29 is insufficient, and there is a possibility that the mold is likely to lose its shape when it is taken out from the die 19 for firing or in the firing step after removal. Further, even if the pressure exceeds 686 MPa, the effect of further increasing the strength of the compression molded body 29 cannot be obtained, and the press die 20 for performing the high pressure compression molding becomes too large.

When the heat spreader 1 of the example of FIGS. 1 to 4 is manufactured, the frame 3 has a substantially rectangular shape in which the outer peripheral surface 17 is along the inner peripheral surface 18 of the die 19 and the inner peripheral surface is along the outer edge of the substrate 2. In addition to forming an annular shape, a bulging portion 10 is projected from a plurality of locations on the inner periphery (in this example, 3 locations on the long side, 6 locations in total) inward in the surface direction. The frame body 3 is integrally formed of the above-described aluminum or aluminum alloy.

Further, as the

thin plates

22 and 26, a flat plate shape having a planar shape that matches the planar shape in the ring of the frame body 3 and fitted to the frame body 3 is used. That is, as the

thin plates

22 and 26, the outer periphery is a substantially rectangular flat plate shape along the inner peripheral surface of the ring of the frame body 3, that is, the outer edge of the planar shape of the base material 2, and corresponds to the bulging portion 10 of the outer periphery. In this case, those provided with notches having a planar shape that matches the planar shape of the bulging portion 10 are used. Each of the

thin plates

22 and 26 is integrally formed of the aluminum or aluminum alloy described above.

A predetermined clearance is set in the fitting portion between the inner periphery of the frame 3 and the outer periphery of the

thin plates

22 and 26. Thereby, on the boundary line between the frame 3 and the

thin plates

22 and 26 among the front surface 11 and the rear surface 12 of the heat spreader 1 manufactured through the respective steps based on the clearance, that is, the position along the outer edge of the base material 2. Thus, the

grooves

13 and 14 are accurately formed. Further, in the ring of the frame 3 having a predetermined size and shape set in the region 21 in advance, the mixture 25 filled later is sintered at a temperature not higher than the melting point of the aluminum or aluminum alloy so that the base material 2 is Since it is formed, it is possible to prevent the base material 2 from being largely displaced in the heat spreader 1 to be manufactured.

The thickness of the

thin plates

22 and 26 is preferably 0.05 mm or more. Thereby, the groove |

channels

13 and 14 of the magnitude | size which can be visually recognized enough visually can be formed in the surface 11 and the back surface 12 of the heat spreader 1 by the said mechanism. The thickness of the

thin plates

22 and 26 is preferably 1 mm or less even within the above range. Thereby, the thickness of the coating layers 6 and 7 to be formed is made as small as possible, and the element is formed on the basis of the difference in thermal expansion coefficient between the aluminum or aluminum alloy forming the coating layers 6 and 7 and the element or ceramic substrate. It is possible to prevent the element itself from being damaged due to excessive stress and the solder joint from being destroyed.

Further, the clearance of the fitting portion between the inner periphery of the frame 3 and the outer periphery of the

thin plates

22 and 26 is preferably 0.05 mm or more and 0.5 mm or less. When the clearance is 0.05 mm or less, there is a possibility that the

grooves

13 and 14 having a size that can be sufficiently visually recognized cannot be formed on the front surface 11 and the back surface 12 of the heat spreader 1 by the mechanism. On the other hand, when the thickness exceeds 0.5 mm, the formed

grooves

13 and 14 become too large, and the accuracy of alignment of the base material 2 by the

grooves

13 and 14 may be lowered.

In addition, the area of the heat spreader 1 in the same direction is used to securely surround the outer periphery of the substrate 2 with the frame 3 over the entire circumference, or the area of the element mounting surface defined by the area of the substrate 2 in the surface direction. In order to improve as much as possible the area ratio represented by the ratio of the inside, the thickness of the frame 3 in the surface direction (distance between the outer peripheral surface 17 and the inner peripheral surface) is 1 mm or more, 20 mm or less, particularly 5 mm. As mentioned above, it is preferable that it is 15 mm or less.

The heat spreader 1 formed through the above steps may be further pressurized under heating. Thereby, the deformation | transformation (distortion etc.) which generate | occur | produces at the time of baking, the unevenness | corrugation etc. which generate | occur | produce on the surface 11 and the back surface 12 can be corrected, and the base material 2 can be densified and thermal conductivity can be improved.
Specifically, the heat spreader 1 after firing is set again in the region 21 of the press die 20 shown in FIG. 5, and this time the jig 23 is not set, and the planar shape of the contact surface is on the heat spreader 1. An upper punch having a shape matching the planar shape of the surface 11 of the heat spreader 1 is brought into contact. When the upper punch is pushed in the direction of the lower punch 16 while being heated to a predetermined temperature and pressed in the thickness direction, the deformation of the heat spreader 1 and the unevenness of the front surface 11 and the back surface 12 are corrected, and the base material 2 is densely formed. To improve the thermal conductivity.

In the pressurizing step, the heating temperature (mold temperature) is used in order to correct the deformation and unevenness as well as possible and improve the thermal conductivity while maintaining the

grooves

13 and 14 in a state that is easy to visually recognize. ) Is preferably 300 ° C. or more and 650 ° C. or less, the pressure of the pressurization is 245 MPa or more and 490 MPa or less, and the pressurization time is 0.1 seconds or more and 5 seconds or less. Further, in order to correct the deformation of the heat spreader 1 and the unevenness of the front surface 11 and the back surface 12 and to increase the density of the substrate 2, for example, a process such as hot forging may be employed instead of the pressurizing process. Absent.

FIG. 10 is a cross-sectional view showing one process of another example of the production method of the present invention. Referring to FIG. 10, in this example, the region 21 of the press die 20 is made of aluminum or an aluminum alloy instead of the frame 3 and the thin plate 22, and has a shape in which the frame 3 and the thin plate 22 are integrated. The point which sets the molded object 30 to have differs from the previous example. Subsequent steps are performed in the same manner as in the previous example. In the manufacturing method, the portion corresponding to the frame body 3 in the molded body 30 and the thin plate 26 constituting the coating layer 6 on the surface 4 side of the base material 2 fitted in the ring of the portion are fitted. A groove 13 is formed on the surface 11 of the heat spreader 1 by the above mechanism based on the clearance set in the portion.

<Method for manufacturing heat spreader (part 2)>
In the heat spreader 1 of the present invention, the base 2 is made of any of the materials (1) to (9) and the frame 3 and the covering layers 6 and 7 are both made of copper or a copper alloy. It can manufacture with the manufacturing method of this invention demonstrated to. 11 to 13 are cross-sectional views showing the steps of an example of the manufacturing method.

With reference to FIGS. 1 to 4 and 11, in the manufacturing method of this example, first, the lower punch 16 having a bottom surface 15 having a planar shape that matches the planar shape of the back surface 12 of the heat spreader 1 to be manufactured, A press die 20 including a die 19 having an inner peripheral surface 18 that surrounds the bottom surface 15 and has a shape that matches the shape of the side surface 17 of the heat spreader 1 is prepared. In the example shown in the figure, the lower punch 16 and the die 19 are formed separately. However, for simplification, both are formed integrally, or the lower opening of the die 19 is replaced with an anvil instead of the lower punch 16. You can close it with Moreover, the positional relationship of each part which comprises the press die 20 may be upside down from the figure.

Next, referring to FIG. 12, a base material 2 formed in a predetermined three-dimensional shape in advance in a region 21 surrounded by the bottom surface 15 and the inner peripheral surface 18 of the press die 20, and the base material 2. An annular frame 3 that surrounds the frame 3 and a fitting portion between the frame 3 and a predetermined clearance, and is fitted onto the frame 3 in a state of being overlapped with the front surface 4 and the back surface 5 of the substrate 2. The two

thin plates

22 and 26 to be the

layers

6 and 7 are set.

Of these, the base material 2 may be made of any one of the materials (1) to (9) and formed in advance into a predetermined shape by any of the manufacturing methods described above. The base material 2 covers the entire surface with a copper plating film in advance. This prevents materials other than copper from being exposed on the surface, and when the substrate 2 is heat-treated at a temperature equal to or lower than the melting point of copper or copper alloy while being pressed in the press die 20, the substrate 2 is made of copper or copper. It can be satisfactorily integrated with the frame 3 made of an alloy and the

thin plates

22 and 26.

The base material 2, the frame body 3, and the

thin plates

22 and 26 may be set in the region 21 in the state illustrated in the figure outside the region 21, or may be assembled in the state illustrated in the region 21. Good.
Next, referring to FIG. 13, on the frame 3 and the thin plate 26 set in the region 21, the upper punch 32 in which the planar shape of the contact surface 31 is the same as the planar shape of the surface 11 of the heat spreader 1. The upper punch 32 is pushed in the direction of the lower punch 16 and pressed in the thickness direction, and heat-treated at a temperature below the melting point of copper or copper alloy. Then, the frame 3 is integrated with the base material 2, and the

thin plates

The temperature of heat processing should just be below the melting point of copper or a copper alloy. However, in order to manufacture the heat spreader 1 in which the frame 3 and the

thin plates

22 and 26 are integrated with the base material 2 as firmly as possible, the heat treatment temperature is preferably 300 ° C. or more and 600 ° C. or less. . For the same reason, the heat treatment time is preferably 0.5 hours or more and 2 hours or less.
The pressure during compression molding is preferably 49 MPa or more and 196 MPa or less. If the pressure is less than 49 MPa, the heat spreader 1 in which the frame 3 and the

thin plates

22 and 26 are firmly integrated with the base material 2 may not be manufactured. Further, even if the pressure exceeds 196 MPa, no further effect of firmly integrating the frame 3 and the

thin plates

22 and 26 with the base material 2 can be obtained, and the press die 20 for performing the high-pressure compression molding. There is also a problem that becomes too large.

When the heat spreader 1 of the example of FIGS. 1 to 4 is manufactured, the frame 3 has a substantially rectangular shape in which the outer peripheral surface 17 is along the inner peripheral surface 18 of the die 19 and the inner peripheral surface is along the outer edge of the substrate 2. In addition to forming an annular shape, a bulging portion 10 is projected from a plurality of locations on the inner periphery (in this example, 3 locations on the long side, 6 locations in total) inward in the surface direction. The frame 3 is integrally formed as a whole by the copper or copper alloy described above.

Further, as the

thin plates

22 and 26 is integrally formed of copper or a copper alloy described above.

thin plates

22 and 26. Thereby, on the boundary line between the frame 3 and the

thin plates

grooves

13 and 14 are accurately formed. Further, since the heat spreader 1 is manufactured by fitting the base material 2 into the ring of the frame 3 having a predetermined size and shape set in the region 21 in advance, the base material 2 is largely displaced in the heat spreader 1. Can also be prevented.

The thickness of the

thin plates

22 and 26 is preferably 0.05 mm or more. Thereby, the groove |

channels

thin plates

22 and 26 is preferably 1 mm or less even within the above range. Thereby, the thickness of the coating layers 6 and 7 to be formed is made as small as possible, and the element is formed on the basis of the difference in thermal expansion coefficient between the copper or copper alloy forming the coating layers 6 and 7 and the element or the ceramic substrate. It is possible to prevent the element itself from being damaged due to excessive stress and the solder joint from being destroyed.

thin plates

grooves

13 and 14 may be lowered.

Although not shown, a molded body having a shape obtained by integrating the frame 3 and one thin plate is used, and the molded body, the base material 2 and the other thin plate are set in the region 21 and compression molded. May be. In this case, based on the clearance of the fitting portion between the portion corresponding to the frame 3 in the molded body and the thin plate fitted in the ring of the portion, the front surface 11 or the back surface 12 of the heat spreader 1 by the above mechanism. A groove is formed in one of them.

<Method for manufacturing heat spreader (others)>
The heat spreader 1 in which the substrate 2 is made of the aluminum-ceramic composite material (1) and the frame 3 and the coating layers 6 and 7 are made of aluminum or an aluminum alloy is manufactured as described above with reference to FIGS. It can be manufactured not only by the method but also by the manufacturing method shown in FIGS.

That is, with reference to FIG. 11 and FIG. 12, the base material 2 previously formed into a predetermined three-dimensional shape by any one of the methods (1-1) to (1-3) is attached to the frame 3 and the

thin plates

22, 26. At the same time, it is set in the region 21 of the press die 20.
Next, referring to FIG. 13, the upper punch 32 is brought into contact with the frame 3 and the thin plate 26 set in the region 21, and the upper punch 32 is pushed in the direction of the lower punch 16 and pressed in the thickness direction. It heat-processes below the melting point of aluminum or aluminum alloy, Preferably it is 550 degreeC or more and 650 degrees C or less.

Then, the frame 3 is integrated with the base material 2, and the

thin plates

22 and 26 are integrated with the base material 2 to form the covering layers 6 and 7, whereby the heat spreader 1 shown in FIGS. 1 to 4 is manufactured. The Moreover, based on the clearance set in the fitting part between the frame 3 and the

thin plates

22 and 26, the frame 3 and the

thin plates

22 and 26 out of the front surface 11 and the back surface 12 of the heat spreader 1 by the mechanism described above. The

grooves

13 and 14 are accurately formed on the boundary line between the two, that is, at a position along the outer edge of the substrate 2.

In addition, it cannot be overemphasized that it replaces with the frame 3 and one thin plate, and the molded object which formed both integrally in this manufacturing method may be used. In this case, on the one of the front surface 11 and the rear surface 12 of the heat spreader 1 based on the clearance set in the fitting portion between the portion corresponding to the frame 3 and the other thin plate in the molded body. A groove is formed.

The heat spreader 1 made of a combination of other materials other than the above can also be manufactured by an arbitrary manufacturing method according to the characteristics of each material.
For example, the heat spreader 1 in which the base material 2 is made of the aluminum-ceramic composite material (1), the coating layers 6 and 7 are made of aluminum or an aluminum alloy, and the frame 3 is made of copper or a copper alloy is, for example, the base material 2 and a thin plate After the

laminates

22 and 26 are produced and the side surfaces thereof are coated with a copper plating film, the combination with the frame 3 made of copper or copper alloy is set in the region 21 of the press die 20 and compression molded. At the same time, it is manufactured by heat treatment below the melting point of copper or copper alloy, preferably at 300 ° C. or more and 600 ° C. or less.

The laminate of the base material 2 and the

thin plates

22 and 26 is formed by compressing the mixture 25 and the

thin plates

22 and 26, which are the basis of the base material 2, in a predetermined press die, and then aluminum or It can be formed by firing below the melting point of the aluminum alloy, preferably 550 ° C. or higher and 650 ° C. or lower. Further, the base material 2 formed by the methods (1-1) to (1-3) and the

thin plates

22 and 26 may be laminated and fired at the above temperature to form a laminate.

The configuration of the present invention is not limited to the example of the figure described above. For example, the heat spreader 1 in the example shown in the figure has a flat plate shape, and has

grooves

13 and 14 serving as marks for soldering the elements and the ceramic substrate on both the front surface 11 and the back surface 12. By using the described molded body 30 or the like, for example, the groove 13 can be formed only on the front surface 11 and the groove 14 on the back surface 12 can be omitted. Further, the coating layer 7 constituting the back surface 12 without the grooves 14 is integrally formed with a large number of fins or pins protruding from the back surface 12 in the thickness direction, and the heat spreader 1 of the present invention is used as a part of the heat sink. Is also possible. In addition, various design changes can be made without departing from the scope of the present invention.

<Example 1>
The heat spreader 1 having a substantially rectangular flat plate shape shown in FIGS. 1 to 4 and having a width of 180 mm, a length of 90 mm, and a thickness of 3.0 mm is manufactured by the manufacturing method of FIGS. A mold 20 or the like was prepared.
(Mixture 25 which becomes the base material 2)
A mixture 25 was prepared by blending 65 parts by mass of silicon carbide powder (average particle size 50 μm) as a ceramic powder and 35 parts by mass of aluminum powder (average particle size 50 μm).

(Frame 3)
The thickness is 3.0 mm which matches the thickness of the heat spreader 1, the outer periphery is a rectangular shape of 180 mm wide × 90 mm long which matches the outer periphery of the planar shape of the heat spreader 1, and the inner periphery is 160 mm wide along the outer edge of the planar shape of the base material 2 The bulging part 10 for forming the screw hole 8 is formed in a rectangular shape with a length of 70 mm, and protrudes inward in the surface direction from each of three locations on the long side of the rectangular shape in the inner circumference. A rectangular annular frame 3 was integrally formed of aluminum.

(

Thin plates

22 and 26 on which the coating layers 6 and 7 are based)
A thin plate provided with a notch having a planar shape that is a substantially rectangular flat plate shape along the inner edge of the frame 3 and that coincides with the planar shape of the bulging portion 10 from the outer periphery toward the inner side in the surface direction. 22 and 26 were integrally formed of aluminum. The thickness of the

thin plates

22 and 26 was set to 0.3 mm, and the clearance with the frame 3 was set to 0.15 mm.

(Press die 20)
A lower punch 16 having a bottom surface 15 having a planar shape that matches the planar shape of the back surface 12 of the heat spreader 1 to be manufactured, and an inner peripheral surface that surrounds the bottom surface 15 and has a shape that matches the shape of the side surface 17 of the heat spreader 1. The die 19 having 18 was formed separately from each other by stainless steel.

(Jig 23)
An annular jig 23 having the same planar shape as the frame 3 was formed of stainless steel.
(Upper punch 28)
The upper punch 28 in which the planar shape of the contact surface 27 coincides with the planar shape of the thin plate 26 was formed of stainless steel.

(Manufacture of heat spreader 1)
The press die 20 is fitted into the ring frame 3 and the ring of the frame body 3 in a region 21 surrounded by the bottom surface 15 and the inner peripheral surface 18 to cover the back surface 5 of the substrate 2. In the region 24 surrounded by the thin plate 22, the frame 3, and the jig 23 in a state where the thin plate 22 to be the covering layer 7 to be set is set and the annular jig 23 is set on the frame 3. After charging 75 g of the mixture 25, a thin plate 26 was stacked on the mixture 25.

Next, with the contact surface 27 of the upper punch 28 in contact with the thin plate 26, the upper punch 28 is moved in the direction of the lower punch 16, and the thickness of the heat spreader 1, that is, the thickness of the frame 3 (= 3). To obtain a compression-molded body 29 by pressing it at a pressure of 490 MPa until it reaches a thickness of 0.0 mm), and then removing the compression-molded body 29 from the press die 20 and firing at 650 ° C. for 2 hours. A heat spreader 1 was manufactured.

Next, the heat spreader 1 is set again in the region 21 of the press die 20 that has been heated to 400 ° C. in advance, and this time, the jig 23 is not set, and the planar shape of the contact surface on the heat spreader 1 is the heat spreader 1. An upper punch having a shape coinciding with the planar shape of the surface 11 was brought into contact. Then, the upper punch is pushed in the direction of the lower punch 16 and pressure is applied under the conditions of a pressure of 294 MPa and a pressurization time of 2 seconds to correct the deformation of the heat spreader 1 and the unevenness of the front surface 11 and the back surface 12 and the substrate 2 Density was increased to improve thermal conductivity.

(External appearance and observation of cut surface)
When the appearance of the heat spreader 1 was observed,

grooves

13 and 14 were observed on the front surface 11 and the rear surface 12 as shown in FIGS. Therefore, the heat spreader 1 was cut so as to straddle the

grooves

13 and 14, and an optical micrograph of the cut surface was taken and observed. As shown in FIG. 14, the groove 13 (the groove 14 was also the same) was inside. It was confirmed that it was formed along the outer edge of the substrate 2 [photographed as an aggregate of a large number of particles (ceramic powder)]. Further, from the photograph, the deviation G ₁ in the surface direction between the outer edge 2a of the substrate 2 and the deepest point 13a in the cross section in the width direction of the groove 13 was measured and found to be 0.23 mm. Further, from the result of confirming the position of the base material 2 by ultrasonic inspection, it was confirmed that the

grooves

13 and 14 were formed along the outer edge of the base material 2 inside.

The coefficient of thermal expansion of the region surrounded by the grooves 13 in the surface 11 of the heat spreader 1 was measured using a differential thermal dilatometer to be 8.5 × 10 ⁻⁶ / K. Further, when the thermal conductivity between the region surrounded by the groove 13 in the front surface 11 of the heat spreader 1 and the region surrounded by the groove 14 in the back surface 12 was measured by the laser flash method, it was 185 W / m · K. there were.
(Processing test)
When the screw hole 8 is formed on the bulging portion 10 of the heat spreader 1 by using a normal cutting tool, the predetermined screw hole can be obtained in a short time without touching the base material 2 and damaging the cutting tool. 8 could be formed.

<Example 2>
A molded body 30 having a shape in which the frame 3 and the thin plate 22 having the same shape and the same dimensions as those used in Example 1 were integrally formed of aluminum was prepared. Then, the heat spreader 1 is manufactured in the same manner as in Example 1 except that the molded body 30 is combined with the same thin plate 26, mixture 25, press die 20, jig 23, and upper punch 28 as used in Example 1. did.

(External appearance and observation of cut surface)
When the appearance of the heat spreader 1 was observed, grooves 13 were observed only on the surface 11 as shown in FIGS. Therefore, the heat spreader 1 was cut so as to straddle the groove 13, and an optical micrograph of the cut surface was taken and observed. As a result, the groove 13 was formed along the outer edge of the substrate 2 inside as shown in FIG. Was confirmed. Further, from the photograph, the deviation G ₁ in the surface direction between the outer edge 2a of the substrate 2 and the deepest point 13a in the cross section in the width direction of the groove 13 was measured and found to be 0.34 mm. Further, from the result of confirming the position of the base material 2 by ultrasonic inspection, it was confirmed that the groove 13 was formed along the outer edge of the internal base material 2.

Further, the coefficient of thermal expansion of the region surrounded by the groove 13 in the surface 11 of the heat spreader 1 was measured using a differential thermal dilatometer to be 9.1 × 10 ⁻⁶ / K. Further, the thermal conductivity between the region surrounded by the grooves 13 in the front surface 11 of the heat spreader 1 and the central portion in the rear surface 12 was measured by a laser flash method to be 195 W / m · K.
(Processing test)
When the screw hole 8 is formed on the bulging portion 10 of the heat spreader 1 by using a normal cutting tool, the predetermined screw hole can be obtained in a short time without touching the base material 2 and damaging the cutting tool. 8 could be formed.

<Comparative example 1>
A mixture obtained by mixing 70 parts by mass of silicon carbide powder having an average particle diameter of 50 μm and 30 parts by mass of silicon carbide powder having an average particle diameter of 10 μm with a binder such as a resin was molded and then fired to obtain a width of 159.7 mm × length of 69. A notch 9 corresponding to a bulging portion 10 for forming a screw hole 8 is formed in a rectangular flat plate shape of 7 mm × thickness 2.4 mm and from the three long sides of the rectangle toward the inner side in the surface direction. A porous body having was prepared.

Then, the porous body is melted by being heated above the melting point in a state where the casting mold is set in a cavity having a width of 180 mm, a length of 90 mm, and a depth of 3.0 mm, which matches the three-dimensional shape of the frame. The cast aluminum alloy was poured to impregnate the porous body, and a frame body and a coating layer were integrally formed around it, and then removed from the mold to obtain a heat spreader 1.
When the appearance of the heat spreader 1 was observed, the front surface 11 and the back surface 12 thereof were both smooth and the

grooves

13 and 14 were not observed, and the position of the internal substrate 2 could not be specified from the appearance. Then, when the position of the base material 2 was confirmed by ultrasonic inspection, it was confirmed that the base material 2 was shifted from the regular position by about 3 mm in the surface direction of the heat spreader 1.

In order to prevent deviation, the porous body is set in the cavity in a state of being fitted in the ring of the same frame body 3 used in Example 1, and is heated and melted in the cavity to a melting point or higher. The aluminum alloy was poured and impregnated into the porous body to form a coating layer and integrated with the frame, and then removed from the mold to obtain the heat spreader 1. And when the position of the base material 2 was confirmed by ultrasonic inspection, the base material 2 was no longer displaced, but the front surface 11 and the back surface 12 were both smooth and the

grooves

13 and 14 were not observed. The position of the internal substrate 2 could not be specified from the appearance.

<Example 3>
As the heat spreader 1 having a substantially rectangular flat plate shape having a width of 50 mm, a height of 50 mm, and a thickness of 1.5 mm, the following various materials, a press die 20 and the like were prepared.
(Substrate 2)
A substantially rectangular flat plate made of a copper-molybdenum composite material and having a width of 10 mm, a length of 10 mm, and a thickness of 0.5 mm was formed using molybdenum instead of tungsten in the method (4-2). The ratio of copper and molybdenum was 30/70 by mass ratio. Next, the entire surface of the flat plate was covered with a copper plating film to form a substrate 2.

(Frame 3)
The thickness is 1.4 mm, the outer periphery is a rectangular shape of 50 mm in width and 50 mm in length that matches the outer periphery of the planar shape of the heat spreader 1, and the inner periphery is a rectangular shape of 10 mm in width and 10 mm in length along the outer edge of the planar shape of the substrate 2. The annular frame 3 was integrally formed of copper.
(

Thin plates

22 and 26 on which the coating layers 6 and 7 are based)
The

thin plates

22 and 26 whose planar shape was a rectangular flat plate shape along the inner edge of the frame body were integrally formed of copper. The thickness of the

thin plates

22 and 26 was set to 0.5 mm, and the clearance with the frame 3 was set to 0.1 mm.

(Press die 20)
A lower punch 16 having a bottom surface 15 having a planar shape that matches the planar shape of the back surface 12 of the heat spreader 1 to be manufactured, and an inner peripheral surface that surrounds the bottom surface 15 and has a shape that matches the shape of the side surface 17 of the heat spreader 1. A die 19 having 18 is formed separately from stainless steel.

(Upper punch 32)
The upper punch 32 having a shape in which the planar shape of the contact surface 31 coincides with the planar shape of the surface 11 of the heat spreader 1 was formed of stainless steel.
(Manufacture of heat spreader 1)
In the area 21 surrounded by the bottom surface 15 and the inner peripheral surface 18 of the press die 20, the base material 2, the annular frame 3 surrounding the base material 2, the front surface 4 and the back surface of the base material 2. The two

thin plates

22 and 26 fitted on the frame 3 in a state of being overlaid on 5 were set.

Next, with the abutment surface 31 of the punch 32 in contact with the frame 3 and the thin plate 26, the upper punch 32 is pressed in the direction of the lower punch 16 at a pressure of 118 MPa while being compression-formed in the thickness direction. The press mold 20 was heated to 400 ° C. in a vacuum furnace. Then, when the heating of the vacuum furnace was stopped and the temperature in the furnace decreased to room temperature, the press die 20 was taken out, and then the heat spreader 1 was taken out from the press die 20.

(External appearance and observation of cut surface)
When the appearance of the heat spreader was observed,

grooves

13 and 14 were observed on the front surface 11 and the back surface 12, respectively. Therefore, the heat spreader 1 was cut so as to straddle the

grooves

13 and 14, and an optical micrograph of the cut surface was taken and observed. As shown in FIG. 15, the groove 13 (the groove 14 was also the same) was formed inside. It is formed along the outer edge of the base material 2 (rectangular region defined by vertical and horizontal lines (boundary lines between the base material 2 and the thin plate 22 (26) and the frame body 3) in the lower left of the figure). confirmed. Further, from the photograph, the deviation G ₁ in the surface direction between the outer edge 2a of the substrate 2 and the deepest point 13a in the cross section in the width direction of the groove 13 was measured and found to be 0.21 mm. Further, from the result of confirming the position of the base material 2 by ultrasonic inspection, it was confirmed that the

grooves

13 and 14 were formed along the outer edge of the base material 2 inside.

The coefficient of thermal expansion of the region surrounded by the grooves 13 in the surface 11 of the heat spreader 1 was measured using a differential thermal dilatometer to be 9.7 × 10 ⁻⁶ / K. Further, when the thermal conductivity between the region surrounded by the groove 13 in the front surface 11 of the heat spreader 1 and the region surrounded by the groove 14 in the back surface 12 was measured by the laser flash method, it was 236 W / m · K. there were.

Claims

A flat substrate;
An annular frame made of metal or alloy and surrounding the outer periphery in the surface direction of the substrate and integrated with the substrate;
A thin plate-like coating layer made of the same or different metal or alloy as the frame and coated on the front and back surfaces of the base material;
A flat plate-shaped heat spreader comprising:
At least one of the front surface and the back surface of the heat spreader composed of the coating layer and the frame has a groove along the outer edge of the internal substrate in the surface direction of the front surface or the back surface.
2. The heat spreader according to claim 1, wherein the substrate has a thermal expansion coefficient of 15 × 10 −6 / K or less and a thermal conductivity of 150 W / m · K or more.
The substrate is
(1) Aluminum-ceramic composite material,
(2) Copper-ceramic composite material,
(3) silicon-ceramic composite material,
(4) Copper-tungsten composite material,
(5) Copper-molybdenum composite material,
(6) Tungsten,
(7) molybdenum,
(8) Aluminum-silicon composite material, and
(9) The heat spreader according to claim 1 or 2, comprising at least one selected from the group consisting of copper-diamond composite materials.
The heat spreader according to any one of claims 1 to 3, wherein the frame body and the coating layer are made of aluminum, an aluminum alloy, copper, or a copper alloy.
The heat spreader according to any one of claims 1 to 4, wherein the thickness is 1 mm or more.
The heat spreader according to any one of claims 1 to 5, wherein the groove has a width of 0.02 mm or more and a depth of 0.01 mm or more.
7. The heat spreader according to claim 1, wherein the substrate is made of an aluminum-ceramic composite material or an aluminum-silicon composite material, and the frame and the covering layer are made of aluminum or an aluminum alloy. A manufacturing method comprising:
The bottom surface of the press die including a lower punch having a bottom surface having a planar shape that matches the planar shape of the heat spreader, and a die having an inner peripheral surface that surrounds the bottom surface and that has a shape that matches the shape of the side surface of the heat spreader. In the region surrounded by the inner peripheral surface, the annular frame body has a predetermined clearance at the fitting portion between the frame body and is fitted to the frame body to be one of the front surface or the back surface of the base material A step of setting a thin plate to be a coating layer that covers the surface, or setting a molded body having a shape in which the frame and the thin plate are integrated;
A step of setting an annular jig having the same planar shape as the frame on the set frame or molded body;
A mixture of aluminum or aluminum alloy powder and ceramic powder or a mixture of aluminum or aluminum alloy powder and silicon powder is formed in the region surrounded by the thin plate, frame and jig, or molded body and jig. Filling, and
On the mixture, in a state where a predetermined clearance is provided at a fitting portion with a frame body, and a thin plate that is fitted to the frame body and serves as a covering layer that covers the other of the front surface and the back surface of the base material is overlapped, A step of compression molding in the thickness direction of the heat spreader to obtain a compression molded body,
Firing the compression-molded body at a temperature below the melting point of aluminum or aluminum alloy;
The manufacturing method of the heat spreader characterized by including.
The method for producing a heat spreader according to claim 7, wherein the compression molded body is fired after being taken out of the press die.
The method of manufacturing a heat spreader according to claim 7 or 8, wherein the thin plate has a thickness of 0.05 mm or more.
The method for manufacturing a heat spreader according to any one of claims 7 to 9, wherein the clearance between the fitting portion of the frame and the thin plate is 0.05 mm or more.
The method for producing a heat spreader according to any one of claims 7 to 10, wherein the pressure at the time of compression molding is 98 MPa or more and 686 MPa or less.
The manufacturing method for manufacturing a heat spreader according to any one of claims 1 to 6, wherein the frame and the coating layer are made of copper or a copper alloy.
Producing a substrate;
A step of copper plating the surface of the substrate;
The bottom surface of the press die including a lower punch having a bottom surface having a planar shape that matches the planar shape of the heat spreader, and a die having an inner peripheral surface that surrounds the bottom surface and that has a shape that matches the shape of the side surface of the heat spreader. In the area surrounded by the inner peripheral surface,
(a) The base material, an annular frame surrounding the base material, and a fitting portion between the frame body have a predetermined clearance, and the frame body is overlaid on the front surface and the back surface of the base material. Set two thin plates that are fitted together to form a coating layer, or
(b) The base material, a molded body having a shape in which the frame body and one thin plate are integrated, and a fitting portion between the frame body and a predetermined clearance, and a front surface or a back surface of the base material A step of setting the other thin plate that is fitted to the frame body to be a covering layer in a state of being overlaid on,
A step of heat-treating each part at a temperature below the melting point of copper or copper alloy while compression-molding each part in the thickness direction of the heat spreader;
The manufacturing method of the heat spreader characterized by including.
The method of manufacturing a heat spreader according to claim 12, wherein the thickness of the thin plate is 0.05 mm or more.
The method of manufacturing a heat spreader according to claim 12 or 13, wherein the clearance between the fitting portion of the frame and the thin plate is 0.05 mm or more.