JPWO2009116245A1 - Heat spreader and manufacturing method thereof - Google Patents

Abstract

This invention is made of a composite material, and can be easily processed to form pins, screw holes, through holes, etc., or can be easily connected to other members using the pins, screw holes, through holes, etc. Thus, there are provided a heat spreader that does not cause various problems and a manufacturing method for efficiently manufacturing the heat spreader with as few steps as possible. The heat spreader 1 includes a base material 2 made of an aluminum-ceramic composite material or the like, and the base material 2 joined to the base material 2 in a state of being penetrated into the base material 2 from at least one surface of the base material 2. It includes a connection member 3 for connecting to the member. The manufacturing method is such that after the connecting member 3 made of aluminum or an alloy thereof is set on the bottom surface 16 of the press die 20, the mixture 23 that becomes the base material 2 is filled and compression-molded, and then the aluminum or an alloy thereof is used. Calcination at a melting point of

Description

  The present invention relates to a heat spreader used for removing heat from a semiconductor element, and a manufacturing method thereof.

For example, a resin-encapsulated package of a semiconductor element has a semiconductor element mounted on the surface of a flat heat spreader that also serves as a semiconductor element mounting substrate fixed to the lead frame, and the semiconductor element and the lead frame are connected by wire bonding or the like. In addition, after the semiconductor element is sealed with resin, the lead frame is cut out and manufactured.
At least a part of the back surface of the heat spreader is sealed with a sealing resin so as to be thermally connected to, for example, a cooler or a heat sink, and to quickly remove heat from the semiconductor element via the cooler or the heat sink. It is common to expose without stopping.

The heat spreader is generally formed of a metal such as aluminum or copper, or an alloy thereof. The heat spreader is fixed to the lead frame by, for example, inserting a pin integrally formed by protruding from the back surface of the heat spreader through a through hole provided in the lead frame (for example, Patent Document 1, 2).
The fixing by the caulking process is simple in structure and work process for fixing and can be downsized, and is excellent in fixing accuracy. Therefore, particularly in a small resin-sealed package, a lead frame and a heat spreader Widely adopted for fixing.

In a larger heat spreader or the like, another member such as a heat sink is connected by screwing a screw into a screw hole provided in the heat spreader or by inserting a screw through the through hole.
In recent years, the heat spreader is made of an aluminum-ceramic composite material in place of the metal or alloy, has a thermal conductivity equivalent to that of the metal or alloy, and has a heat conductivity with a semiconductor material that forms a semiconductor element to be mounted. The use of a material having a close expansion coefficient has been studied.

By using the heat spreader in combination with a semiconductor element, the stress applied to the semiconductor element can be reduced based on the difference in thermal expansion coefficient between the two when the heat generation due to the operation of the semiconductor element and the cooling after the stop are repeated. .
For this reason, when the heat generation and cooling are repeated, excessive stress is applied to the semiconductor element, causing the semiconductor element to malfunction, reducing the efficiency of operation, or being damaged, or between the semiconductor element and the heat spreader. It is possible to prevent the solder joint or the like from being broken (see, for example, Patent Document 3).
JP-A-6-177268 JP-A-8-130273 JP-A-8-222660

However, when the heat spreader having the pins is formed of the composite material described above, there is a problem that the heat spreader cannot be fixed to the lead frame satisfactorily by caulking as in the prior art.
That is, a heat spreader in which the whole including the pins is integrally formed of a composite material is difficult to caulk itself because most of the composite material is very hard and more brittle than metals and alloys. Nevertheless, when the pins are forcibly processed, cracks or cracks are likely to occur in the pins themselves or in the portions around the pins of the heat spreader, as is apparent from the results of comparative examples described later.

Accordingly, it is conceivable to fix a pin made of a metal or an alloy that can be easily caulked to the back surface of a heat spreader formed of a composite material by soldering or the like.
However, the pins fixed by soldering or the like are likely to fall off due to impact or the like during caulking, as is apparent from the results of comparative examples described later. Therefore, there is a problem that the heat spreader cannot be fixed to the lead frame with a high yield without causing the above-mentioned dropout or the like.

Also, the pin is likely to be displaced. Therefore, there is also a problem that the heat spreader cannot be fixed to the lead frame with high accuracy without causing the above-mentioned positional deviation or the like.
In paragraph [0042] of Patent Document 3, there is a description that a heat spreader made of a composite material may be fixed to a lead frame using a mechanical coupling means such as caulking. However, the details are unknown. Patent Document 3 does not describe at all how a heat spreader made of a composite material is caulked and fixed to a lead frame. In addition, there is no description of any means for solving the above problems.

In Patent Document 3, the main method for fixing the heat spreader and the lead frame is bonding by an adhesive to the last, and fixing by caulking is only described additionally. From this, it is considered that the description in the paragraph [0042] merely describes a desire.
Moreover, in the adhesion | attachment by the adhesive agent described in patent document 3, a fixed time is required until an adhesive agent hardens | cures, and a shift | offset | difference etc. are easy to produce. Therefore, there is a problem that the heat spreader cannot be fixed to the lead frame efficiently and accurately.

Further, when the heat spreader having screw holes and through holes is integrally formed of the composite material, there are the following problems.
That is, as described above, many of the composite materials are very hard and difficult to process. Therefore, in order to form a screw hole or a through hole in the heat spreader made of the composite material, it is necessary to use a cemented carbide tool such as an expensive diamond tool. Moreover, even if a cemented carbide tool or the like is used, it takes much time and time to form screw holes and through holes as compared to metal or alloy processing.

Furthermore, since many composite materials are more fragile than metals and alloys, cracks, cracks, etc. occur around the screw holes and through-holes during the processing or when connecting screws to other members. It is easy to do.
It is an object of the present invention to be made of a composite material and processed to form pins, screw holes, through holes, etc., or to be connected to other members using the pins, screw holes, through holes, etc. It is an object of the present invention to provide a heat spreader that is easy and does not cause various problems, and a manufacturing method for efficiently manufacturing the heat spreader with as few steps as possible.

The present invention includes a base material and a connection member made of a metal or an alloy and connecting the base material to another member, and the connection member penetrates into the base material from at least one surface of the base material. It is a heat spreader characterized by being joined to the substrate in a state.
According to the present invention, for example, a pin for connecting to another member is integrally formed on one surface side of the connecting member by projecting from the one surface to the outside of the base material. Compared to the case where the surfaces are simply joined and fixed, the substrate can be fixed more firmly.

  That is, the connection member can be more firmly fixed to the base material by three-dimensionally joining the base portion of the connection member penetrating into the base material with the base material surrounding the base member. Therefore, the pin or the entire connecting member is more reliably prevented from dropping from the base material due to impact or the like when the pin formed integrally with the connecting member is caulked and connected to a lead frame or the like. Can be prevented.

Therefore, by forming the whole connecting member including the pin with a metal or an alloy that can be easily caulked, the heat spreader can be accurately and yielded by the caulking of the pin, and can be favorably applied to the lead frame and the like. Can be fixed.
Further, a screw hole or a through hole may be formed by drilling, tapping or the like from the one surface side of the connection member toward the inside of the base material. In that case, by forming the connecting member with a metal or an alloy that can be easily drilled or tapped, the screw hole or thread can be easily and quickly used without using a carbide tool or the like. A hole can be formed.

In addition, since the connection member made of the metal or alloy is not brittle like a base material made of a composite material, cracks, cracks, etc. around the screw hole or the through hole, etc. during the processing or when tightening the screw, etc. Can also be prevented.
In the heat spreader of the present invention, the base material is formed in a flat plate shape, and the connection member surrounds the periphery in a state of being penetrated in the thickness direction of the base material so as to reach the surface from the back surface of the base material It is preferable that a pin for connecting to another member is integrally formed on the back surface side of the connection member so as to protrude from the back surface to the outside of the base material.

According to the heat spreader having the above-described structure, most of the load applied in the thickness direction of the base material at the time of caulking of the pin is released from the back surface side of the base material to the front surface side through the connection member itself, thereby the base material. The load directly applied to can be greatly reduced. Therefore, it is possible to reliably prevent the base material from being cracked or cracked, and to further improve the yield during caulking.
In the heat spreader of the present invention, the base material is formed in a flat plate shape, and the connecting member surrounds the base material in a state of being penetrated in the thickness direction of the base material so as to reach the surface from the back surface of the base material. The connecting member is formed with a screw hole into which a screw for connecting to another member is screwed or a through hole through which the screw is inserted, from the back surface side to the front surface side. It is preferable.

  According to the heat spreader having the above-described structure, most of the load applied in the thickness direction of the base material at the time of processing such as drilling and tapping is released from the back surface side of the base material to the front surface side through the connection member itself. The load applied directly to the substrate can be greatly reduced. Therefore, it is possible to reliably prevent the base material from being cracked or cracked during the processing, and to further improve the yield during the drilling or tapping processing.

In addition, the connection member can receive stress applied in the thickness direction of the base material when a screw that is screwed into the screw hole or inserted through the through hole for connection with another member is tightened. Therefore, it is possible to more reliably prevent the base material from being cracked or cracked when connected to another member.
As the base material, those made of various composite 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. By forming the base material with a composite material satisfying such conditions, heat from the semiconductor element etc. can be transferred as quickly as possible while preventing various problems based on the difference in thermal expansion coefficient from the semiconductor element etc. Can be removed.

As the substrate, for example,
(1) Aluminum-ceramic composite material,
(2) Copper-ceramic composite material,
(3) Copper-tungsten composite material,
(4) Copper-molybdenum composite material,
(5) an aluminum-silicon composite material, and
(6) There may be mentioned at least one selected from the group consisting of copper-diamond composite materials.

As the metal or alloy forming the connecting member, the workability when processing to form pins, screw holes, through holes, etc., the workability when caulking the pins and connecting to other members, etc. In addition to being excellent, it is possible to use any of various metals or alloys that are not brittle like a base material made of a composite material and thus are less prone to cracks and cracks.
Among them, a metal having a Vickers hardness Hv = 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 base material is composed of a composite material including a metal or alloy forming a connection member and a sinterable metal or alloy, and the metal or alloy in the base material and the metal or alloy forming the connection member are: It is preferable that the base material and the connecting member are bonded together by sintering the composite material to form a base material. With this configuration, the connecting member can be bonded to the base material with higher accuracy and as firmly as possible.

  The present invention is a manufacturing method for manufacturing the heat spreader of the present invention, wherein the base material is a flat plate made of an aluminum-ceramic composite material or an aluminum-silicon composite material, and the connecting member is made of aluminum or an aluminum alloy. A lower punch having a bottom surface that has a planar shape that matches the planar shape of the back surface of the substrate, and a die that has an inner peripheral surface that surrounds the bottom surface and matches the shape of the side surface of the substrate. A step of setting a connecting member at a predetermined position on the bottom surface of the press die, and a mixture of aluminum or aluminum alloy powder and ceramic powder in a region surrounded by the bottom surface and inner peripheral surface of the press die Or filling a mixture of aluminum or aluminum alloy powder and silicon powder; and Obtaining a compression molded to compression moldings countercurrent, the compression-molded body, characterized in that it comprises a step of calcining an aluminum or aluminum alloy having a melting point below the temperature.

According to the manufacturing method of the present invention, the powder of the mixture is sintered in the baking step to form a base material having a shape in which the connection member penetrates into the base material, and in the base material By sintering aluminum or an aluminum alloy with aluminum or an aluminum alloy forming the connection member, the base material and the connection member can be firmly bonded.
In the manufacturing method, the connecting member is set at a predetermined position of the lower punch to prevent displacement, and the firing temperature is set to a temperature equal to or lower than the melting point at which the aluminum or aluminum alloy melts and does not flow significantly. In combination with the fact that the base material and the connection member are strongly sintered by the firing, the connection member can be accurately joined to a predetermined position of the base material. Therefore, according to the manufacturing method of the present invention, the heat spreader of the present invention can be efficiently manufactured with as few steps as possible.

In the said manufacturing method, it is preferable to bake, after taking out a compression molding body from a press die.
In other words, the compression molded body taken out from the press mold can be baked as it is or in a simple (small heat capacity) mold form to prevent the deformation of the mold, thereby reducing the energy and time required for the calcination. it can.

  In order to manufacture the heat spreader in which the pins protrude from the back surface of the flat substrate to the outside of the substrate by the manufacturing method of the present invention, the pins formed integrally with the connection member are formed on the bottom surface of the lower punch. A recessed portion to be inserted is provided, and the pin is inserted into the recessed portion and the connecting member is set on the bottom surface, and the base material is formed in a region surrounded by the bottom surface and the inner peripheral surface of the press die. The mixture may be filled, compression molded, and fired.

Moreover, when manufacturing the heat spreader which a connection member has a screw hole or a through-hole by the manufacturing method of this invention, it is preferable to form a screw hole or a through-hole in the connection member after baking a compression molding body.
That is, the accuracy of the screw holes and through-holes can be increased by forming screw holes or through-holes later in the connection member joined to the base material through compression molding and firing processes. Further, the solid connection member before forming the screw hole or the through hole is compression-molded with the composite material to form the base material, and the base material and the connection member are joined to increase the strength of the joint. You can also.

  According to the present invention, it is made of a composite material and processed to form a pin, a screw hole, a through hole, or the like, or connected to another member using the pin, the screw hole, the through hole, or the like. It is easy to provide a heat spreader that does not cause various problems, and a manufacturing method for efficiently manufacturing the heat spreader with as few steps as possible.

It is a perspective view which shows the external appearance of an example of embodiment of the heat spreader of this invention. It is an expanded sectional view which expands and shows the junction part of the connection member which has a pin, and a base material which are the principal parts of the heat spreader of the example of FIG. It is an expanded sectional view which shows the modification of the said junction part. It is a perspective view which shows the external appearance of the other example of embodiment of the heat spreader of this invention. It is an expanded sectional view which expands and shows the junction part of the connection member which has a screw hole, and a base material which are the principal parts of the heat spreader of the example of FIG. It is an expanded sectional view showing a modification of the connection member. It is an expanded sectional view showing other modifications of the connection member. It is an expanded sectional view showing other modifications of the connection member. It is sectional drawing which shows 1 process of an example of the manufacturing method of the heat spreader of this invention for manufacturing the heat spreader of FIG. It is sectional drawing which shows the next process of the said manufacturing method. It is sectional drawing which shows the next process of the said manufacturing method. It is sectional drawing which shows the next process of the said manufacturing method. It is sectional drawing which shows the next process of the said manufacturing method. It is sectional drawing which shows the precursor of a heat spreader obtained by further baking the compression molding body formed through the said each process. It is sectional drawing which shows 1 process of the other example of the manufacturing method of the heat spreader of this invention for manufacturing the heat spreader of FIG. 4 thru | or FIG. It is sectional drawing which shows the next process of the said manufacturing method. It is sectional drawing which shows the next process of the said manufacturing method. It is sectional drawing which shows the next process of the said manufacturing method. It is sectional drawing which shows the precursor of a heat spreader obtained by further baking the compression molding body formed through the said each process. It is an optical microscope photograph which shows the cut surface of the junction part of the connection member which has a pin of the heat spreader manufactured in Example 1, and a base material.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Heat spreader 2 Base material 3 Connection member 4 Back surface 5 Surface 6 Base 7 Pin 8 Thick part 9 Upper surface 10 Screw hole 11, 12 Cover layer 13 Through-hole 14 Compression molding 15 Precursor 16 Bottom surface 17 Lower punch 18 Inner peripheral surface 19 Die 20 Press die 21 Recess 22 Recess 23 Mixture 24 Contact surface 25 Upper punch 26, 28 Thin plate 27, 29 Through hole 30 Through hole

<Heat spreader>
FIG. 1 is a perspective view showing an appearance of an example of an embodiment of a heat spreader of the present invention. FIG. 2 is an enlarged cross-sectional view showing a joint portion between a connecting member having a pin and a base material, which is a main part of the heat spreader in the example of FIG.
1 and 2, a heat spreader 1 of this example includes a base material 2 formed entirely in a rectangular flat plate shape by, for example, an aluminum-ceramic composite material, and positions corresponding to the four rectangular corners of the base material 2. The four connection members 3 provided in the above are provided.

  Each connection member 3 has a back surface 4 (a surface to which other members such as a lead frame (not shown) are connected, an upper surface in both figures) to a front surface 5 (a surface on which a semiconductor element (not shown) is mounted, both figures, respectively. In the thickness direction so as to reach the lower surface), a base portion 6 that is three-dimensionally joined to the base material 2 surrounding the entire circumference of the periphery, and other members that protrude upward from the back surface 4 And a pin 7 for connection. In this example, the base 6 and the pin 7 are integrally formed in a cylindrical shape having the same outer diameter by a metal or an alloy.

  According to the heat spreader 1 of this example having the connecting member 3, the pin 7 is formed on the base material as compared with the conventional case where the pins are simply joined to each other on the back surface of the base material by soldering or the like. 2 can be bonded more firmly. That is, the cylindrical base portion 6 formed integrally with the pin 7 is three-dimensionally joined to the base material 2 surrounding the entire outer periphery thereof, thereby connecting the connecting member 3, that is, the pin 7 to the base material 2. Can be joined more firmly.

Therefore, it is possible to more reliably prevent the connecting member 3 having the pins 7 from dropping from the base material 2 due to an impact or the like when the pins 7 are caulked and connected to a lead frame or the like.
Moreover, in the heat spreader 1 of this example, since the base portion 6 is penetrated in the thickness direction so as to reach the surface 5 of the base material 2 as described above, the load applied in the thickness direction of the base material 2 during the caulking processing of the pin 7 is reduced. Most part can escape from the back surface 4 side of the base material 2 to the front surface 5 side through the connection member 3 itself. Therefore, the load directly applied to the base material 2 can be significantly reduced, and the base material 2 can be reliably prevented from being cracked or cracked, and the yield during caulking can be further improved.

Therefore, according to the heat spreader 1 of this example, the entire connection member 3 including the pins 7 is formed of a metal or an alloy that can be easily caulked, so that the heat spreader 1 can be accurately obtained by caulking of the pins 7. Moreover, it can be fixed to a lead frame or the like with good yield.
The base material 2 has a rectangular thick portion 8 that protrudes upward from the back surface 4 at the center of the back surface 4. The thick part 8 is formed integrally with the base material 2 by the composite material or the like. The upper surface 9 in the figure of the thick portion 8 can be exposed without being sealed with the sealing resin as described above, and can function as an exposed surface for cooling.

FIG. 3 is an enlarged cross-sectional view showing a modified example of the joining portion.
With reference to FIG. 3, in this example, the connecting member 3 is positioned in the middle of the thickness direction from the back surface 4 of the base material 2 without penetrating the base portion 6 in the thickness direction so as to reach the surface 5 of the base material 2. It is joined to the base material 2 in a state of being penetrated to the end. Also in this case, the pin 7 can be bonded to the base material 2 more firmly than in the case where the pins are simply bonded to each other on the back surface of the base material by soldering or the like.

That is, the cylindrical base portion 6 is three-dimensionally joined to the base member 2 that surrounds the entire outer periphery of the cylindrical base portion 6 and is in contact with the lower end face in FIG. The material 2 can be bonded more firmly.
As the connection member 3, those having various dimensions according to the size and position of the heat spreader 1 and the lead frame, the shape and size of the semiconductor element to be mounted, the shape and size of the resin-sealed package, etc. can be used.

  For example, in the connection member 3 in which the base 6 and the pin 7 are integrally formed in a cylindrical shape having the same outer diameter as described above, the protruding height of the pin 7 from the back surface 4 is 0.5 mm or more. The entire length of the connecting member 3 is set to be 0 mm or less, particularly around 1.0 mm, and the diameter of the connecting member 3 is set to 0.5 mm or more and 5.0 mm or less, particularly about 1.0 mm. Is preferred.

If the protruding height of the pin 7 is less than 0.5 mm, there is a possibility that a sufficient crushing allowance by caulking cannot be secured. If it exceeds 2.0 mm, the pin 7 may not protrude straight from the back surface 4 in the vertical direction. In this case, it is difficult to fit the lead frame.
When the diameter of the connecting member 3 is less than 0.5 mm, the pin 7 is inserted into the recess 22 of the lower punch 17 to set the connecting member 3 particularly when the heat spreader 1 is manufactured by the manufacturing method of the present invention described later. If it exceeds 5.0 mm, a space for arranging the connecting member 3 on the base material 2 of the heat spreader 1 for a resin-sealed package having a limited size, and a through hole in the lead frame It may be difficult to secure a space to be formed.

The depth of penetration of the base 6 into the base 2 is up to the thickness of the base 2 as described above, that is, up to the state where the base 6 is penetrated to the surface 5 of the base 2 as shown in FIG. This state is most preferable.
Moreover, as shown in FIG. 3, when making the base part 6 penetrate in the middle of the thickness direction of the base material 2, it is preferable to make the penetration depth into 0.2 mm or more. When the depth of penetration is less than 0.2 mm, the connecting member 3 is joined in a three-dimensional manner with the base 2 that surrounds the entire circumference of the base 6 described above and is in contact with the lower end surface. There is a possibility that the effect of bonding more strongly to the base material 2 cannot be obtained.

The position where the base portion 6 is penetrated is preferably a position that is 0.2 mm or more inside from the periphery in the surface direction of the substrate 2. When the base 6 is inserted at a position closer to the periphery than the range, there is a risk that the heat spreader 1 may fall off the lead frame due to a crack on the periphery of the base 6 of the base 2 due to impact during caulking. There is.
The clearance between the recess 22 of the lower punch 17 and the pin 7 is preferably set to 0.02 mm or more and 0.1 mm or less. If the clearance is less than 0.02 mm, particularly when the heat spreader 1 is manufactured by the manufacturing method of the present invention, which will be described later, it is difficult to insert the pin 7 into the recess 22 and set the connecting member 3. In the case of exceeding the above, at the time of compression molding, it becomes difficult for the metal or alloy in the composite material constituting the base material 2 to enter the clearance, so that it becomes difficult to take out the compression molded body after molding from the press die 20. There is a fear.

FIG. 4 is a perspective view showing the appearance of another example of the embodiment of the heat spreader of the present invention. FIG. 5 is an enlarged cross-sectional view showing a joint portion between a connection member having a screw hole and a base material, which is a main part of the heat spreader in the example of FIG.
4 and 5, the heat spreader 1 of this example includes a base material 2 formed entirely in a rectangular flat plate shape, and four connection members 3 provided at positions corresponding to the four corners of the rectangle of the base material 2. And.

Each connecting member 3 has a back surface 4 of the base material 2 (a surface to which other members such as a cooler and a heat sink (not shown) are connected, an upper surface in both figures) to a front surface 5 (a surface on which a semiconductor element is mounted, both figures. In the state penetrated in the thickness direction so as to reach the lower surface), the base material 2 surrounding the entire circumference is joined.
Further, the connection member 3 is formed with a screw hole 10 through which the screws for connecting to other members are screwed from the back surface 4 to the front surface 5 so as to penetrate between the both surfaces 4 and 5. . In this example, the connecting member 3 is integrally formed of a metal or alloy in a cylindrical shape having the same outer diameter, and the screw hole 10 is provided so as to be substantially coaxial with the central axis.

  In the heat spreader 1 of this example having the connecting member 3, the connecting member 3 is formed of a metal or an alloy that can be easily drilled or tapped to form the screw hole 10. The screw hole 10 can be formed easily and in a short time without using a carbide tool or the like. Further, since the connecting member 3 made of metal or alloy is not brittle like a composite material, cracks or cracks may occur around the screw hole 10 during the processing or when tightening the screw. Can be prevented.

  Moreover, since the heat spreader 1 of this example has the connecting member 3 penetrated in the thickness direction so as to reach the surface 5 of the base material 2 as described above, processing such as drilling and tapping for forming the screw holes 10 is performed. Sometimes, most of the load applied in the thickness direction of the base material 2 can escape from the back surface 4 side to the front surface 5 side of the base material 2 through the connection member 3 itself. Therefore, the load directly applied to the base material 2 can be significantly reduced, and it is possible to reliably prevent the base material 2 from being cracked or cracked during the processing, thereby further improving the yield during drilling or tapping processing.

In addition, the connecting member 3 can receive stress applied in the thickness direction of the base material 2 when a screw screwed into the screw hole 10 is tightened for connection with another member. Therefore, it is possible to more reliably prevent the base material 2 from being cracked or cracked when connected to another member.
Moreover, in the heat spreader 1 of this example, the back surface and the surface of the base material 2 are covered with thin plate-like coating layers 11 and 12, and the upper exposed surface in both drawings of the coating layer 11 is the back surface 4 of the base material 2. The exposed surface on the lower side of the coating layer 12 is the surface 5 of the substrate 2.

The covering layers 11 and 12 are formed of the same or different metal or alloy as that for forming the connection member 3. In particular, it is preferably formed of various metals or alloys having a good thermal conductivity equal to or higher than that of the substrate 2.
A semiconductor element or a ceramic substrate on which a semiconductor element is mounted can be satisfactorily soldered to the surface 5 of the base material 2 constituted by the coating layer 12 without generating voids that hinder heat conduction.

That is, in order to satisfactorily solder the semiconductor element, the ceramic substrate or the like to the surface 5 of the base material 2, it is preferable to coat the surface 5 with a nickel plating film having excellent wettability and affinity for solder. .
However, on the surface of the base material 2 made of the composite material, the plating conditions vary greatly between various materials constituting the composite material, for example, metal, alloy and ceramic, so that the surface is stable and uniform directly on the surface. It is difficult to form a nickel plating film or the like.

On the other hand, when the surface 5 of the base material 2 is composed of a smooth coating layer 12 made of a single metal or alloy, a stable and uniform nickel plating film or the like can be formed on the coating layer 12. Therefore, the element, the ceramic substrate, etc. can be satisfactorily soldered to the surface on which the nickel plating film or the like is formed without generating voids that hinder heat conduction.
Moreover, a nickel plating film etc. can also be abbreviate | omitted using what was excellent in the wettability with respect to a solder as a metal or alloy which comprises the coating layer 12, and affinity.

Moreover, the smoothness of the said back surface 4 can be improved by comprising the back surface 4 of the base material 2 with the coating layer 11, and adhesiveness with the cooler, heat sink, etc. which are fixed to the said back surface 4 with a screw | thread can be improved. .
6 to 8 are enlarged sectional views showing modifications of the connecting member 3. With reference to FIG. 6, the screw hole 10 may be opened only on the back surface 4 side without opening on the front surface 5 side of the substrate 2. Further, referring to FIG. 7, the connecting member 3 is not penetrated in the thickness direction so as to reach the front surface 5 of the base material 2, but penetrates from the back surface 4 of the base material 2 to a position in the middle of the thickness direction. And may be joined to the substrate 2.

Further, referring to FIG. 8, the connection member 3 may be formed with a through hole 13 instead of the screw hole 10. In this case, for example, a screw hole is formed in the cooler or the heat sink, and the screw inserted through the through hole 13 is screwed into the screw hole, so that the cooler or the heat sink is connected to the back surface 4 side of the substrate 2. Is done.
The connecting member 3 has various dimensions according to the size of the heat spreader 1, the cooler, the heat sink, the shape and size of the semiconductor element to be mounted, the size of the screw that is screwed into the screw hole, the size of the screw that is inserted into the through hole, and the like. Can be used.

For example, in the connection member 3 that is integrally formed in a cylindrical shape as described above and has the screw hole 10 and the through hole 13 so as to be substantially coaxial with the central axis thereof, the diameter thereof is set to the screw hole 10 or the through hole 13. It is preferable that the inner diameter is set to 1.2 times or more and 3.0 times or less, particularly 1.5 times or more and 2.0 times or less.
When the diameter of the connecting member 3 is less than 1.2 times the inner diameter of the screw hole 10 or the through hole 13, the connecting member 3 is too thin to form the screw hole 10 or the through hole 13 substantially coaxially with the central axis. Processing may not be easy. Moreover, stress at the time of processing may be applied to the base material 2 and the base material 2 may be easily cracked or cracked. Further, the thickness of the connecting member 3 after the screw hole 10 and the through hole 13 are formed becomes too thin, and the connecting member 3 sufficiently receives the stress applied in the thickness direction of the base material 2 when the screw is tightened. Therefore, the base material 2 may be easily cracked or cracked.

Further, when the diameter of the connecting member 3 exceeds 3.0 times the inner diameter of the screw hole 10 or the through-hole 13, damage to the base material 2 due to the difference in thermal expansion coefficient between the base material 2 and the connecting member 3 is large. There is a risk of becoming too much. Further, the screw holes 10 and the through holes 13 cannot be disposed in the vicinity of the outer peripheral edge of the heat spreader 1 and the design freedom of the heat spreader 1 may be reduced.
The depth of penetration of the connecting member 3 into the base material 2 is the thickness of the base material 2 as described above, that is, as shown in FIGS. 4 to 6 and FIG. This state is most preferable.

  Further, as shown in FIG. 7, when the connection member 3 is penetrated partway along the thickness direction of the substrate 2, the penetration depth is preferably 1.0 times or more the inner diameter of the screw hole 10. . By setting the penetration depth to be 1.0 times or more of the inner diameter of the screw hole 10, a sufficient screw tightening margin can be secured in the screw hole 10 formed in the connection member 3. Therefore, the heat spreader 1 can be securely fixed to a cooler, a heat sink, or the like with screws.

The position where the connecting member 3 is penetrated is preferably a position that enters 0.2 mm or more from the peripheral edge in the surface direction of the substrate 2. When the connection member 3 is inserted at a position closer to the periphery than the above range, the connection member of the base material 2 is caused by a stress at the time of forming the screw hole 10 or the through hole 13 or a stress at the time of tightening the screw. There is a possibility that a crack is generated on the peripheral side from 3.
In any of the heat spreaders 1 shown in FIGS. 1 to 7, the thermal expansion coefficient of the substrate 2 is preferably 15 × 10 ⁻⁶ / K or less.

  Thereby, the difference of a thermal expansion coefficient with the semiconductor element etc. which consist of various semiconductor materials can be made small. Therefore, when the heat generation due to the operation of the semiconductor element and the cooling after the stop are repeated, the semiconductor element itself is damaged or malfunctions due to excessive stress applied to the semiconductor element based on the difference in coefficient of thermal expansion. It is possible to suppress the reduction in the efficiency of the operation or the destruction of the solder joint or the like between the semiconductor element and the heat spreader 1.

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 base material 2 preferably has a thermal expansion coefficient of 2 × 10 ⁻⁶ / K or more even within the above range.
The thermal expansion coefficient of the base material 2 made of a 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 may be set according to the circumstances specific to each material.
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) Copper-tungsten composite material,
(4) Copper-molybdenum composite material,
(5) an aluminum-silicon composite material, and
(6) There may be mentioned at least one selected from the group consisting of copper-diamond composite materials.

Of 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, when manufacturing the heat spreader 1 by the manufacturing method of the present invention to be described later, the base material 2 formed in a state of being joined to the connecting member 3 is formed by the methods (1-1) and (1-2). It corresponds to.

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 such as A2014, A3004, and A5005 An alloy-based material or powder such as a casting aluminum-based alloy such as AC3A or AC4A can also be used.

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 aluminum alloy and ceramic can be distributed as finely and evenly 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 aluminum alloy and ceramic can be distributed as finely and evenly 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. However, as described above, the thermal expansion coefficient of the base material 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 mixture ratio of both powders so that the thermal expansion coefficient of the said base material 2 may become the 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.

Examples of the base material 2 made of the copper-tungsten composite material (3) include those formed by the following forming method.
(3-1) 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.
(3-2) The porous body made of tungsten formed in the shape of the base material 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 (3-2) 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 (3-2) 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 (4) include those formed in the same manner as the copper-tungsten composite material (3) 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 (3-2) is described in detail in JP-A-59-21032.

  Examples of the base material 2 made of the aluminum-silicon composite material of (5) 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. . 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 a state of being joined to the connection member 3 is made of (1-1) (1-2) It corresponds to the one formed in the same way as the method.

Further, examples of the base material 2 made of the copper-diamond composite material (6) include those formed by the forming method described in JP-A No. 2004-175626.
As the metal or alloy forming the connection member 3, workability for processing into a predetermined shape of the connection member 3 in advance, workability when caulking the pins 7, screw holes 10, and through holes 13 are formed. Any of various metals or alloys excellent in workability at the time 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.

It is also important that the connecting member 3 is formed of a composite material composing the base material 2 and a sinterable metal or alloy.
For example, when the base material 2 is made of the aluminum-ceramic composite material (1) or the aluminum-silicon composite material (5), the metal or alloy serving as the base of the connecting member 3 that satisfies the above-mentioned conditions is as follows: Examples thereof include aluminum or aluminum alloys such as alloy numbers A1050, A2014, A3004, and A5005 defined in the above-mentioned JIS H4000: 2006.

  When the substrate 2 is composed of (2) copper-ceramic composite material, (3) copper-tungsten composite material, (4) copper-molybdenum composite material, or (6) copper-diamond composite material, Examples of the metal or alloy serving as the base of the connecting member 3 that satisfies each condition include copper or copper such as alloy numbers C1020 “oxygen-free copper” and C1100 “tough pitch copper” defined in the above JIS H3100: 2006. An alloy etc. are mentioned.

  The metal or alloy for forming the coating layers 11 and 12 is excellent in the effect of providing the coating layers 11 and 12 described above, and the thickness of the thin plate that forms the coating layers 11 and 12 is made as uniform as possible. Any of various metals or alloys excellent in workability for finishing or the like 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.

It is also important that the coating layers 11 and 12 are formed of a composite material or a connecting member 3 constituting the base material 2 and a metal or alloy that can be sintered.
For example, when the substrate 2 is made of the aluminum-ceramic composite material (1) or the aluminum-silicon composite material (5) and the connecting member 3 is made of aluminum or an aluminum alloy, the metal or alloy satisfying the above-mentioned conditions Is preferably a pure aluminum-based spreading material such as alloy numbers A1050, A1070, and A1100 defined in JIS H4000: 2006, and a casting alloy such as AC3A and AC4A.

  Further, the base member 2 is composed of the copper-ceramic composite material (2), the copper-tungsten composite material (3), the copper-molybdenum composite material (4), or the copper-diamond composite material (6). When 3 is made of copper or a copper alloy, the metal or alloy satisfying the above-mentioned conditions is preferably alloy numbers C1020 “oxygen-free copper”, C1100 “tough pitch copper” or the like defined in JIS H3100: 2006. .

<Method for manufacturing heat spreader (part 1)>
The heat spreader 1 of the present invention has the structure shown in FIGS. 1 to 3, the substrate 2 is made of the aluminum-ceramic composite material (1) or the aluminum-silicon composite material (5), and the connecting member 3 is What consists of aluminum or an aluminum alloy can be manufactured with the manufacturing method of this invention.

9 to 13 are cross-sectional views showing respective steps of an example of the manufacturing method for manufacturing the heat spreader 1 of the example of FIGS. 1 to 3. Moreover, FIG. 14 is sectional drawing of the precursor 15 of the heat spreader 1 obtained by further baking the compression-molded body 14 formed through each said process.
With reference to FIGS. 1 to 3 and 9, in the manufacturing method of this example, first, a lower punch having a bottom surface 16 having a planar shape that matches the planar shape of the back surface 4 of the base 2 of the heat spreader 1 to be manufactured. A press die 20 including a die 17 having an inner peripheral surface 18 that surrounds the bottom surface 16 and has a shape that matches the shape of the side surface of the substrate 2 is prepared. In the example shown in the figure, the lower punch 17 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 17. You can close it with

Specifically, the bottom surface 16 has a rectangular planar shape corresponding to the planar shape of the back surface 4, and a rectangular concave portion 21 corresponding to the thick portion 8 is formed in the central portion of the rectangle. The three-dimensional shape is formed with the recesses 22 into which the pins 7 of the connecting member 3 protruding from the positions are inserted around the recesses 21 and at four positions corresponding to the four corners of the rectangle.
Next, referring to FIG. 10, the connecting member 3 is set on the lower punch 17 with the pin 7 inserted into the recess 22 of the bottom surface 16 and the base portion 6 protruding from the bottom surface 16.

  Next, referring to FIG. 11, in the region surrounded by the bottom surface 16 and the inner peripheral surface 18 of the press die 20, the aluminum or aluminum alloy powder, the ceramic powder, or the silicon powder that is the base of the substrate 2. And the mixture 23 is filled. The filling amount of the mixture 23 depends on the ceramic powder constituting the mixture 23, the density and particle size of silicon powder, the particle size of aluminum or aluminum alloy powder, the blending ratio of both powders, the density of the base material 2 to be formed, and the like. It can be set as desired.

Next, referring to FIGS. 12 and 13, an upper punch 25 in which the planar shape of the contact surface 24 is a rectangular shape corresponding to the planar shape of the surface 5 of the substrate 2 is brought into contact with the mixture 23. After pressing in the state toward the bottom surface 16 to obtain the compression molded body 14, the compression molded body 14 is fired at a temperature not higher than the melting point of aluminum or aluminum alloy.
Then, the ceramic powder or silicon powder constituting the compression molded body 14 and the aluminum or aluminum alloy powder are sintered to form the substrate 2. At the same time, the base 6 of the connecting member 3 made of aluminum or aluminum alloy is joined to the base material 2 to obtain the precursor 15 of the heat spreader 1 shown in FIG.

  The compression-molded body 14 may be fired by heating means (not shown) together with the press die 20 while maintaining the compression state of FIG. 13 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 14 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.

Therefore, in the present invention, for example, the compression molded body 14 compression-molded at room temperature is not shown in the drawing 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 heat spreader 1 in which the powder of aluminum or aluminum alloy forming the base material 2 and the ceramic powder or silicon powder are bonded as well as possible and the connecting member 3 is bonded as firmly as possible to the base material 2 is as efficient as possible. In order to manufacture well, it is preferable that the temperature of baking is 550 degreeC or more and 650 degreeC or less. 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 14 is insufficient, and there is a risk that the mold may be easily lost when it is taken out from the press die 20 for firing or in the firing step after removal. Further, even if the pressure exceeds 686 MPa, there is a problem that the effect of increasing the strength of the compression molded body 14 cannot be obtained any more, and the press die 20 for performing the high pressure compression molding becomes too large.

Thereafter, when the surface 5 of the base material 2 of the precursor 15 is polished until the end surface of the base 6 is exposed and the thickness between the front surface 5 and the back surface 4 becomes a predetermined thickness of the base material 2. The heat spreader 1 shown in FIGS. 1 and 2 is manufactured.
Further, the amount of protrusion of the base 6 of the connecting member 3 is set to be equal to or less than the thickness of the ground base material 2 to obtain a precursor 15, and the surface 5 of the base material 2 of the precursor 15 is exposed at the end face of the base 6. 1 and FIG. 3 is manufactured by polishing until a predetermined thickness of the base material 2 is reached.

<Method for manufacturing heat spreader (part 2)>
The heat spreader 1 of the present invention has the structure shown in FIGS. 4 to 8, the base material 2 is made of the aluminum-ceramic composite material (1) or the aluminum-silicon composite material (5), and the connecting member 3 is made. Those made of aluminum or an aluminum alloy can be manufactured by another manufacturing method of the present invention.

15 to 18 are cross-sectional views showing respective steps of an example of the other manufacturing method for manufacturing the heat spreader 1 of the examples of FIGS. 4 to 8. FIG. 19 is a cross-sectional view of the precursor 15 of the heat spreader 1 obtained by further firing the compression-molded body 14 formed through the above steps.
Referring to FIGS. 4 to 8 and 15, in the manufacturing method of this example, first, a lower punch having a bottom surface 16 having a planar shape that matches the planar shape of the back surface 4 of the base 2 of the heat spreader 1 to be manufactured. A press die 20 including a die 17 having an inner peripheral surface 18 that surrounds the bottom surface 16 and has a shape that matches the shape of the side surface of the substrate 2 is prepared.

  Further, a thin plate 26 to be the coating layer 11 is set on the bottom surface 16. The thin plate 26 has a rectangular shape that coincides with the planar shape of the back surface 4 of the substrate 2 and is formed with through holes 27 into which the lower ends of the connection members 3 are fitted at positions corresponding to the four corners. The connecting member 3 can be positioned with respect to the lower punch 17 by fitting the lower end portion of the connecting member 3 into the through hole 27.

In the example shown in the figure, the lower punch 17 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 17. You can close it with
Next, referring to FIG. 16, in the state where the lower end portion of the connection member 3 is fitted into the through hole 27 of the thin plate 26 and the connection member 3 is positioned and set with respect to the lower punch 17 as described above, A region 23 surrounded by the bottom surface 16 and the inner peripheral surface 18 of the mold 20 is filled with a mixture 23 of aluminum or aluminum alloy powder that is the base material 2 and ceramic powder or silicon powder.

The filling amount of the mixture 23 depends on the ceramic powder constituting the mixture 23, the density and particle size of silicon powder, the particle size of aluminum or aluminum alloy powder, the blending ratio of both powders, the density of the base material 2 to be formed, and the like. It can be set as desired.
Further, after a predetermined amount of the mixture 23 is filled, a thin plate 28 to be the coating layer 12 is set. The thin plate 28 has a rectangular shape that coincides with the planar shape of the surface 5 of the substrate 2, and is formed with through holes 29 into which the upper ends of the connection members 3 are fitted at positions corresponding to the four corners.

By fitting the upper end of the connection member 3 into the through hole 29, the connection member 3 can be prevented from falling.
As shown in the figure, the connecting member 3 is filled with a mixture 23 in an amount necessary to form the base material 2 having a predetermined thickness. 27 and 29 are formed longer than actually required so that the upper and lower ends can be fitted together.

Next, referring to FIGS. 17 and 18, an upper punch 25 in which the planar shape of the abutting surface 24 is a rectangular shape corresponding to the planar shape of the surface 5 of the substrate 2 is brought into contact with the thin plate 28. In the state, it is pushed in the direction of the bottom surface 16 to obtain the compression molded body 14.
The upper punch 25 is formed with a through hole 30 through which the connection member 3 is inserted during the pushing operation, and the thin plates 26 and 28 and the mixture therebetween while inserting the excess connection member 3 through the through hole 30. 23 can be compression molded to a predetermined thickness.

  Next, the compression molded body 14 is fired at a temperature not higher than the melting point of aluminum or aluminum alloy. Thereby, the ceramic powder or silicon powder which comprises the compression molding body 14, and the powder of aluminum or aluminum alloy are sintered, and the base material 2 is formed. At the same time, the connecting member 3 made of aluminum or an aluminum alloy is joined to the base material 2, and the thin plates 26 and 28 are joined to the base material 2 to form the coating layers 11 and 12, so that the precursor of the heat spreader 1 shown in FIG. A body 15 is obtained.

  As described above, the firing is performed by simply pressing the compression-molded body 14 compression-molded at normal temperature after taking it out of the press die 20 (not shown) or simply for preventing the collapse of the mold (small heat capacity). It is preferable to fire it by fitting it into a mold. Thereby, the energy and time required for firing can be reduced, and the productivity of the heat spreader 1 can be improved. The firing conditions and compression molding conditions are preferably the same as described above.

In FIG. 19, as shown by the broken line, the excess portion of the connecting member 3 protruding downward from the coating layer 12 in the figure is cut. After that, when the screw hole 10 is formed through the drilling and tapping processes in the connecting member 3, the heat spreader 1 shown in FIG. 4, FIG. 5, or FIG. 4, FIG. 6 is manufactured.
When the through holes 13 are formed in the connection member, the heat spreader 1 shown in FIGS. 4 and 8 is manufactured. Furthermore, when the connection member 3 set to the lower punch 17 is shorter than the thickness of the base material 2 after compression molding, the heat spreader 1 shown in FIGS. 4 and 7 is manufactured.

  The configuration of the present invention is not limited to the example of the figure described above. For example, the base material 2 of the heat spreader 1 in the example of FIGS. 1 to 3 has a flat plate shape, a thick portion 8 is formed at the center of the back surface 4, and the connection members 3 are provided at the four surrounding locations. The shape of the material 2 and the arrangement and number of connection members 3 can be arbitrarily set in accordance with the semiconductor element to be combined, the shape of the lead frame, and the like.

Moreover, the base material 2 of the heat spreader 1 of the example of FIGS. 4-8 was flat form, the back surface 4 and the surface 5 were coat | covered with the coating layers 11 and 12, and the connection member 3 was provided in four places of the rectangular four corners. However, the shape and structure of the base material 2 and the arrangement, shape, and number of the connection members 3 can be arbitrarily set in accordance with the shape of the semiconductor element, cooler, and heat sink to be combined.
For example, the heat spreader 1 in the examples of FIGS. 4 to 8 has both end portions of the connection member 3 aligned so as to be flush with both the back surface 4 and the front surface 5 of the base material 2. A portion may be projected from the back surface 4 or the front surface 5 to function as positioning or the like.

  In addition, various design changes can be made without departing from the scope of the present invention.

<Example 1>
A base plate 2 having a rectangular flat shape shown in FIG. 1 (width 80 mm × length 50 mm × thickness 2.0 mm) and having a thick portion 8 of width 40 mm × length 25 mm × height 0.5 mm in the center of the back surface 4; A heat spreader 1 in which four connecting members 3 are joined in a state in which pins 7 (diameter 1.0 mm, projecting height 1.0 mm) are projected upward from positions corresponding to the four corners of the rectangle on the back surface 4 of the substrate 2. Were manufactured through the steps of FIGS. 9 to 14, and the following various materials and press mold 20 were prepared.

(Mixture 23 which becomes the base material 2)
It was prepared by blending 50 parts by mass of silicon carbide powder (average particle size 50 μm) as ceramic powder and 50 parts by mass of aluminum powder (average particle size 50 μm).
(Connecting member 3)
A columnar connecting member 3 made of aluminum having a diameter of 1.0 mm and a length of 3.0 mm was prepared.

(Press die 20)
A bottom surface 16 having a shape matching the shape of the back surface 4 of the heat spreader 1 to be manufactured is provided, and the pins 7 of the connecting member 3 are inserted into the bottom surface 16 at positions corresponding to the four corners of the rectangle. The lower punch 17 provided with a recess 22 having a depth of 0 mm (clearance 0.03 mm with respect to the pin 7) and a depth of 1.0 mm and the shape of the side surface of the base 2 of the heat spreader 1 surrounding the bottom surface 16 were set. The die 19 provided with the inner peripheral surface 18 was separately formed of stainless steel. Further, the upper punch 25 in which the planar shape of the contact surface 24 is a planar shape that matches the planar shape of the surface 5 of the substrate 2 was formed of stainless steel.

(Manufacture of heat spreader 1)
The connection member 3 is set in each of the four recesses 22 of the lower punch 17 (the protruding amount of the base 6 of the set connection member 3 is 2.0 mm), and within the region surrounded by the bottom surface 16 and the inner peripheral surface 18 24.0 g of the mixture 23 is filled, and the upper punch 25 is moved in the direction of the bottom surface 16 until the thickness reaches 3.0 mm with the contact surface 24 of the upper punch 25 being in contact with the mixture 23. After pressing at a pressure of 490 MPa to obtain a compression molded body 14, the compression molded body 14 was taken out from the press die 20 and baked at 650 ° C. for 2 hours to form a precursor 15 of the heat spreader 1.

  Next, the precursor 15 is set again in a region surrounded by the bottom surface 16 and the inner peripheral surface 18 of the press die 20 shown in FIG. With the surface 24 in contact, the upper punch 25 is pushed in the direction of the bottom surface 16 and subjected to a pressure treatment for 2 seconds at a pressure of 294 MPa to deform the base material 2 and the unevenness of the back surface 4 and the front surface 5. Etc. was corrected and the substrate 2 was densified to improve the thermal conductivity.

The surface 5 of the base member 2 is exposed at the end face of the base 6 of the connecting member 3, and the thickness between the front surface 5 and the back surface 4, that is, the thickness of the base member 2 is 1.5 mm (thick portion 8 The heat spreader 1 was manufactured by polishing to a thickness of 2.0 mm.
(External appearance and observation of cut surface)
The appearance of the heat spreader 1 was observed, the heat spreader 1 was cut so as to pass through the axis of the cylinder of the connecting member 3, and the cut surface was photographed and observed. As shown in FIG. It was confirmed that the material 2 and the base 6 of the connecting member 3 were directly joined without a gap.

(Caulking processing test)
100 heat spreaders 1 were prepared, and the pins 7 were inserted into through holes of a lead frame (alloy number C1510 “made of zirconium-containing copper” defined in JIS H3100: 2006, thickness 0.5 mm) and caulked. Later, when the test for observing the appearance was repeated, the number of occurrences of pin cracks, pin dropouts, and base material cracks was counted. As a result, in Example 1, all of the defects (100 It was confirmed that a good caulking process was performed.

<Example 2>
By setting the length of the connection member 3 to 1.3 mm and the protruding amount of the base portion 6 of the connection member 3 set in the recess 22 to 0.3 mm, the base portion 6 is removed from the flat plate back surface 4 as shown in FIG. A heat spreader 1 was manufactured in the same manner as in Example 1 except that the base material 2 was joined in a state of being penetrated to a middle position in the thickness direction.

When 100 heat spreaders were produced and the caulking process test was repeated in the same manner as in Example 1, cracks occurred at positions corresponding to the connecting member 3 on the surface 5 side of the base material 2 in two of the 100 heat spreaders. However, it was confirmed that the remaining 98 pieces were satisfactorily crimped.
<Comparative example 1>
The lower punch 17 is prepared by inserting a pin-shaped movable die through the concave portion 22 to the back surface thereof, and the tip of the movable die is recessed 1.0 mm downward from the bottom surface 16 of the lower punch 17. In the set state, the same compression molding as in Example 1 was performed without setting the connection member 3 in the recess 22.

Next, a heat spreader in which the pins and the substrate were integrally formed of an aluminum-ceramic composite material was manufactured through the same firing and polishing steps as in Example 1.
100 heat spreaders were produced and the caulking process test was repeated in the same manner as in Example 1. As a result, pin cracking occurred in 100 out of 100, and it was confirmed that good caulking could not be performed.

<Comparative example 2>
After preparing a lower punch 17 having no recesses and performing compression molding similar to Example 1, the substrate having no pins is subjected to the same firing and polishing steps as Example 1. Formed. In addition, a cylindrical pin made of aluminum having a diameter of 1.0 mm and a length of 3.0 mm is prepared, and electrolytic nickel plating (thickness: 5 μm) is provided on the entire surface of the pin and on the back surface of the base to the region where the pin is joined. ).

Then, a pin is soldered to the back surface of the base material by heating in a furnace at 250 ° C. with a tin-lead solder (Sn63Pb37) sandwiched between the base material and the pin and fixed with a carbon jig. A heat spreader was manufactured.
100 heat spreaders were produced, and the caulking test was repeated in the same manner as in Example 1. As a result, 46 out of 100 pins were dropped, and 2 were on the surface 5 side of the substrate 2 at positions corresponding to the pins. It was confirmed that a crack was generated, and it was confirmed that good caulking was performed only for 52 of the 100 pieces. The results are shown in Table 1.

<Example 3>
Corresponding to the base plate 2 having a rectangular flat plate shape (width 180 mm × length 90 mm × thickness 5 mm) shown in FIG. In order to manufacture the heat spreader 1 in which the four connecting members 3 having the screw holes 10 at the positions to be bonded are manufactured through the steps of FIGS. 9 to 14, the following various materials and the press die 20 are prepared.

(Mixture 23 which becomes the base material 2)
It was prepared by blending 70 parts by mass of silicon carbide powder (average particle size 50 μm) as ceramic powder and 30 parts by mass of aluminum powder (average particle size 50 μm).
(Connecting member 3)
A columnar connecting member 3 made of aluminum having a diameter of 7.0 mm and a length of 9 mm was prepared.

(Thin plates 26 and 28 on which the coating layers 11 and 12 are based)
Thin plates 26 and 28 made of aluminum having a width of 180 mm, a length of 90 mm, and a thickness of 0.3 mm were prepared. At the four corners of the thin plates 26 and 28, through holes 27 and 29 having an inner diameter of about 7 mm were provided to which both ends of the connecting member 3 were fitted. The clearance between the through holes 27 and 29 and the connection member 3 was 0.05 mm.

(Press die 20)
A lower punch 17 having a bottom surface 16 having a shape that matches the shape of the back surface 4 of the heat spreader 1 to be manufactured, and an inner periphery that surrounds the bottom surface 16 and has a shape that matches the shape of the side surface of the base 2 of the heat spreader 1. The die 19 provided with the surface 18 was formed separately from each other by stainless steel. Further, the planar shape of the contact surface 24 is a planar shape that coincides with the planar shape of the surface 5 of the substrate 2, and the connection member 3 is inserted into the contact surface 24 at positions corresponding to the four corners of the rectangle. The upper punch 25 provided with a through hole 30 having a diameter of about 7 mm was formed of stainless steel.

(Manufacture of heat spreader 1)
With the thin plate 26 set on the bottom surface 16 of the lower punch 17, the bottom surface 16 and the inner peripheral surface 18 are set with the lower end portions of the connection members 3 fitted in the four through holes 27 of the thin plate 26. The enclosed area was filled with 250 g of the mixture 23, the thin plate 28 was stacked on the mixture 23, and the upper end portions of the connection members 3 were fitted into the four through holes 29 of the thin plate 28, respectively.

Next, in a state where the contact surface 24 of the upper punch 25 is in contact with the thin plate 28, the upper punch 25 is pushed in the direction of the bottom surface 16 at a pressure of 490 MPa until the thickness becomes 5 mm, thereby obtaining the compression molded body 14. After that, the compression molded body 14 was taken out from the press die 20 and fired at 650 ° C. for 2 hours to form the precursor 15 of the heat spreader 1.
Next, after cutting the surplus portion of the connecting member 3 protruding from the surface 5 side of the base member 2, the heat spreader 1 is cut so as to pass through the axis of the column of the connecting member 3, and the cut surface is photographed with an optical micrograph. As a result, it was confirmed that the base material 2, the connecting member 3, and the coating layers 11 and 12 were directly joined without a gap.

  Further, after the surplus of the connecting member 3 protruding from the front surface 5 side of the base material 2 of the precursor 15 formed in the same manner is cut, a hole is formed from the back surface 4 side so as to be substantially coaxial with the central axis of the connecting member 3. When the screw hole 10 was formed by tapping processing, it was confirmed that the screw hole 10 can be formed easily and in a short time without using a carbide tool or the like.

Claims (12)

A substrate;
A connection member made of a metal or an alloy, for connecting the base material to another member;
The heat spreader is characterized in that the connection member is joined to the base material in a state of being penetrated into the base material from at least one surface of the base material.   The base material is formed in a flat plate shape, and the connecting member is joined to the base material surrounding the periphery in a state of being penetrated in the thickness direction of the base material so as to reach the surface from the back surface of the base material, and The heat spreader according to claim 1, wherein a pin for connecting to another member is integrally formed on the back surface side of the connecting member so as to protrude from the back surface to the outside of the base material.   The base material is formed in a flat plate shape, and the connecting member is joined to the base material surrounding the periphery in a state of being penetrated in the thickness direction of the base material so as to reach the surface from the back surface of the base material, and 2. The connection member is formed with a screw hole into which a screw for connection with another member is screwed or a through hole into which the screw is inserted, from the back surface side to the front surface side. Heat spreader. 4. The heat spreader according to claim 1, wherein the base material 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) Copper-tungsten composite material,
(4) Copper-molybdenum composite material,
(5) an aluminum-silicon composite material, and
(6) The heat spreader according to claim 4, 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 5, wherein the connecting member is made of a metal or an alloy having a Vickers hardness Hv of 200 or less.   The heat spreader according to claim 6, wherein the connecting member is made of aluminum, an aluminum alloy, copper, or a copper alloy.   The base material is composed of a composite material including a metal or alloy forming a connection member and a sinterable metal or alloy, and the metal or alloy in the base material and the metal or alloy forming the connection member are the composite The heat spreader according to any one of claims 1 to 7, wherein the base material and the connection member are joined to each other by sintering the materials to form a base material. The substrate for manufacturing a heat spreader according to any one of claims 1 to 8, wherein the base member is a flat plate made of an aluminum-ceramic composite material or an aluminum-silicon composite material, and the connecting member is made of aluminum or an aluminum alloy. A manufacturing method comprising:
A lower punch having a bottom surface having a planar shape that matches the planar shape of the back surface of the base material, 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 base material. A step of setting a connecting member at a predetermined position on the bottom surface of the press die;
Filling a region surrounded by a bottom surface and an inner peripheral surface of the press die with a mixture of aluminum or aluminum alloy powder and ceramic powder, or a mixture of aluminum or aluminum alloy powder and silicon powder;
Compression-molding the filled mixture in the direction of the bottom surface 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 9, wherein the compression molded body is fired after being taken out of the press die.   The bottom surface of the lower punch is provided with a recess into which a pin integrally formed with the connection member is inserted, and the pin is inserted into the recess and the connection member is set on the bottom surface. Filling the area surrounded by the peripheral surface with the base material mixture, compression molding, and firing, the pin protrudes from the back surface of the base material corresponding to the bottom surface of the lower punch to the outside of the base material The manufacturing method of the heat spreader of Claim 9 or 10 which manufactures the heat spreader made.   The method for producing a heat spreader according to claim 9 or 10, wherein a screw hole or a through hole is formed in the connection member after the compression molded body is fired.