JP2003110068A - Thermal conduction sheet and its producing method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a thermal conduction sheet, and its producing method, exhibiting high heat dissipation properties to a semiconductor element while suppressing cracking or stripping from the semiconductor element. SOLUTION: The thermal conduction sheet exhibiting excellent heat dissipation properties while suppressing cracking or stripping after being integrated with a semiconductor element can be produced through combination of a resin sheet (sheet-like resin basic material 2) and a thermally conductive wire (thermal conduction path 1).

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a heat conductive sheet and a method for manufacturing the same, and more particularly to a heat conductive sheet which is integrated with a semiconductor element (chip) and used as a heat dissipation member for the semiconductor element and a method for manufacturing the same.

[0002]

2. Description of the Related Art In recent years, the package of a semiconductor device is changing from a package in which a semiconductor element is sealed with a resin to a package which is mounted on a circuit board as it is without sealing the semiconductor element with a resin. Note that the semiconductor element here is also called a bare chip, and refers to a semiconductor element on which a circuit is formed on a crystal substrate (wafer) and cut out. Further, in such a package (semiconductor package), the heat generated in the semiconductor element increases as the degree of integration of the semiconductor element increases and the size of the semiconductor element increases due to technological innovation in the semiconductor field. There is a tendency. Therefore, there is a problem that the heat generated during the operation of the semiconductor element is accumulated inside the semiconductor device, exceeds the junction temperature of the semiconductor element, and falls into a malfunction. Therefore, improvement of heat resistance and heat dissipation is an issue.

In order to solve the above problems, in the above semiconductor package, since the semiconductor element and the sealing resin have extremely low thermal conductivity, for example, in Japanese Patent Laid-Open No. 5-198701, a metal is attached to a die pad fixing the semiconductor element. It has been proposed to stack foils and dissipate heat with this metal foil. However, in this case, due to the imbalance of the constituent materials in the thickness direction of the semiconductor device, that is, the linear expansion coefficient of the metal foil is generally larger than that of the semiconductor element or the die pad, so that the semiconductor element repeatedly generates heat, and There is a problem that repeated stress is generated in the foil, and finally the metal foil peels off or metal fatigue causes cracks in the metal foil.

Further, Japanese Patent Laid-Open No. 63-187652 discloses that a metal foil is attached to one side or both sides of a semiconductor device via an adhesive. However, in this method, since the adhesive layer formed by laminating generally has a high hygroscopic property, a rapid expansion of moisture occurs during soldering, which causes voids or peeling at the interface between the metal foil and the adhesive layer. There's a problem. Furthermore, JP-A-8-1785
Japanese Patent Publication No. 5 discloses a semiconductor device in which the surface of the sealing resin is covered with a metal foil, but even in this case, the problem of peeling or cracking of the metal foil has not been solved.

[0005]

In view of the above circumstances, the present invention shows a high heat dissipation property to a semiconductor element, and further,
It is an object of the present invention to provide a heat conductive sheet which is less likely to cause cracks and detachment from a semiconductor element, and a manufacturing method thereof.

[0006]

Means for Solving the Problems As a result of intensive studies to achieve the above object, the present inventors have found that a combination of a resin sheet and a heat conductive wire has excellent heat dissipation and The present invention has been completed by finding that it is possible to form a heat conductive sheet that is unlikely to be cracked or peeled after being integrated with a semiconductor element. That is, the present invention is as follows. (1) A sheet-shaped resin base material and a plurality of heat conduction paths made of a heat conductive wire, the plurality of heat conduction paths passing from one main surface of the base material to a side surface of the other main surface. A heat conductive sheet, characterized in that it is continuous with the surface and is fixed to the base material. (2) The heat conduction sheet according to (1), wherein the plurality of heat conduction paths are separated from each other and arranged substantially parallel to each other. (3) A plurality of heat conduction paths are continuous from one main surface of the base material to the other main surface through a pair of opposing side surfaces, the above (1) or The heat conductive sheet according to (2). (4) The heat conduction sheet according to any one of (1) to (3) above, wherein the plurality of heat conduction paths form a coil that surrounds the sheet-shaped resin base material. (5) The heat conductive sheet according to any one of (1) to (4) above, wherein the sheet-shaped resin base material is made of an adhesive material. (6) The above-mentioned (1)-
The heat conductive sheet according to any one of (5). (7) The heat conductive wire is made of a carbon material, and the above (1) to
The heat conductive sheet according to any one of (5). (8) The above (1) to be used for a heat dissipation member of a semiconductor element
The heat conductive sheet according to any one of (7). (9) A first step in which a plurality of thermally conductive wires are arranged in parallel on one main surface of the resin sheet and fixed, and the resin sheet is bent, heated and / or pressed with the thermally conductive wires outside. And a second step of fixing the folded surfaces of the other main surface of the resin sheet to each other. (10) The first step of winding a heat conductive wire on the outer peripheral surface of the resin sheet held in a tubular shape with a predetermined gap between the wires, and the heat conduction of the wound wire by heating and / or pressurizing. Second step of fixing the heat-resistant wire to the sheet-shaped resin base material, and a resin sheet held in the above-mentioned tubular shape and having a thermally conductive wire wound around the outer peripheral surface of the resin sheet And a third step of fixing the folded surfaces of the inner peripheral surface of the resin sheet to each other by crushing so as to disappear and heating and / or pressurizing. (11) A coil made of a heat conductive wire, the first step of forming a coil having an internal space capable of accommodating a resin sheet described below, and a resin sheet in the inner space of the coil made of the heat conductive wire. Or a second step of injecting a resin to form a resin sheet, and fixing at least a part of the resin sheet to a coil made of a heat conductive wire by heating and / or pressurizing, A method of manufacturing a heat conductive sheet, comprising a third step of integrating a sheet and a coil made of a heat conductive wire.

In the present specification, the "main surface of the sheet-shaped resin base material" means the surfaces at both ends in the thickness direction of the sheet-shaped resin base material, and the "side surface of the sheet-shaped resin base material" is the main surface. Means other than. Similarly, the “main surface of the resin sheet” means the surfaces at both ends in the thickness direction of the resin sheet. It should be noted that the terms “sheet-shaped resin base material surface” and “resin sheet surface” mean the “main surface of the sheet-shaped resin base material” and the “main surface of the resin sheet”, respectively, unless otherwise specified.

[0008]

DETAILED DESCRIPTION OF THE INVENTION The present invention will be described in detail below with reference to the drawings. 1A and 1B show a first example of the heat conductive sheet of the present invention. FIG. 1A is a top view and FIG. 1B is a side view. The heat conductive sheet of the present invention, as shown in the heat conductive sheet 10 of the first example, includes a sheet-shaped resin base material 2,
A plurality of heat conduction paths 1 made of a heat conductive wire, and the plurality of heat conduction paths 1 from one main surface 2a of the base material 2 to the other main surface 2b via a side surface. And is adhered to the base material 2 continuously. Here, the heat conductive wire means a wire (thin wire) made of a heat conductive material. The heat conductive sheet of the present invention is particularly suitably used as a heat dissipation member that is integrated with a semiconductor element to radiate heat generated by the semiconductor element.

FIG. 2 is a view in which the heat conductive sheet 10 of the first example is integrated with a semiconductor element. As shown in this figure, the heat conductive sheet (heat conductive sheet 10) of the present invention is
The surface of the semiconductor element 3 can be joined and integrated without using an adhesive. That is, in the heat conductive sheet (heat conductive sheet 10) of the present invention, the sheet-shaped resin base material 2 is made of an adhesive resin material, and the sheet-shaped resin base material 2 adheres to the surface of the semiconductor element 3. By that,
It is integrated with the semiconductor element 3. The term "adhesive resin material" as used herein means that it exhibits adhesiveness as it is, or if it does not exhibit adhesiveness as it is, it is heated and / or
Alternatively, it exhibits adhesiveness when pressed. Further, as described in detail later, the heat conductive sheet of the present invention is
Alternatively, pressure and heat are applied to bond (join) to the surface of the semiconductor element to be integrated.

The heat conductive sheet of the present invention (heat conductive sheet 1
0) is integrated with the semiconductor element 3 so that the semiconductor element 3
When the heat is generated, the heat is generated from the portion 1a on one main surface 2a of each sheet-shaped resin substrate 2 of the plurality of heat-conducting paths 1 made of the heat-conductive wire to the other main portion of the sheet-shaped resin substrate 2. Surface 2b
The heat is conducted to the upper portion 1b and radiated to the outside.

FIG. 3 is an enlarged schematic view of the joint between the heat conductive sheet and the semiconductor element in the cross section taken along the line AA in FIG.
As can be seen from this figure, in the heat conducting sheet of the present invention, the plurality of heat conducting paths 1 contact the surface 3a of the semiconductor element 3, and the sheet-shaped resin base material 2 intervenes in the gap of the heat conducting path 1. , Is adhered to the surface 3 a of the semiconductor element 3. Therefore,
Even if the heat conduction path 1 expands or contracts due to the heat generation of the semiconductor element 3, the sheet-shaped resin base material 2 serves as a cushioning material to relax the internal stress that is repeatedly generated in the heat conduction path 1, and Fatigue of 1 is suppressed. Furthermore, since each heat conduction path 1 is surrounded by the adhesive resin material of the sheet-shaped resin base material 2, the adhesiveness with the sheet-shaped resin base material 2 is also good, and from the surface of the semiconductor element 3. Never leave. Therefore, in the heat conductive sheet of the present invention, peeling or cracks from the semiconductor element surface (heat dissipation element (heat conduction path))
The cracks that occur in the above) are suppressed, and since the adhesive is not used when integrated with the semiconductor element unlike the conventional heat dissipation member, the problem caused by using the adhesive described above can be solved.

As shown in the heat conducting sheet 10 of the first example, the heat conducting sheet of the present invention has a plurality of heat conducting paths on the main surface of the sheet-shaped resin base material. It is preferable that the two heat conduction paths that are adjacent to each other (not in contact with each other) are parallel to each other and are spaced at equal intervals. As understood from the (bonding) state of the heat conductive sheet and the semiconductor element described above, all the heat conductive paths are separated (non-contact) from each other, and each two adjacent heat conductive paths. This is because if the distance between the paths is the same, the heat dissipation is good and the adhesive force is improved and uniform. Depending on the pressure (pressurization and heating) conditions and the like in the bonding work, there may be a case where two adjacent heat conduction paths come into contact with each other. Absent.

FIG. 4 shows a second example of the heat conductive sheet of the present invention. FIG. 4 (a) is a top view and FIG. 4 (b) is a side view. In the heat conducting sheet 10 of the first example, each heat conducting path 1 is made continuous from one main surface 2a of the sheet-shaped resin base material 2 to one main surface 2b to the other main surface 2b. That is, in the heat conductive sheet 20 of the second example, each heat conductive path 1 is formed from one main surface 2a of the sheet-shaped resin substrate 2 to a pair of opposite side surfaces 2c-1 and 2c-2. It is made to continue on the other main surface 2b via, and in this point, it differs from the heat conductive sheet of the first example. Heat conductive sheet 20 of the second example
Then, when it is bonded to the surface of the semiconductor element and integrated with the semiconductor element (see FIG. 2), the heat from the semiconductor element conducts through the heat conduction path 1 and the two side surfaces (one set) of the sheet-shaped resin base material. Since the heat is radiated to the outside from the opposite side surfaces), there is an advantage that the heat radiation efficiency is good.

The heat conducting sheet 1 of the first and second examples
In Nos. 0 and 20 (FIGS. 1 and 4), the plurality of heat conduction paths 1 are fixed to the sheet-shaped resin base material 2 over their entire length.
In the present invention, for example, as in the heat conducting sheet 30 of the third example shown in FIG. 5, the heat conducting path 1 may have a portion separated from the sheet-shaped resin base material 2. That is, in the heat conduction sheet 30 of the example of FIG. 5, only the portion of the heat conduction path 1 that is arranged on the main surface 2a intended to be bonded to the semiconductor element surface of the sheet-shaped resin base material 2 is in sheet form. It is fixed to the resin base material 2, and the other parts are separated from the sheet-shaped resin base material 2. It should be noted that this state is just a state before the heat conductive sheet is bonded to the surface of the semiconductor element, and after the heat conductive sheet is bonded to the surface of the semiconductor element (pressurized with the semiconductor element, or heated and pressed. The latter) does not always maintain such a state.

A plurality of heat conduction paths as shown in FIGS. 4 and 5 are continuous from one main surface of the base material to the other main surface through a set of opposing side surfaces. In the heat conduction sheet of the type, the plurality of heat conduction paths may be formed by coils made of heat conduction wire. In addition, the heat conductive sheets 10, 20, 30 of the above first to third examples (FIG. 1,
4 and 5), the outer shape (outer peripheral shape) is rectangular, but in the present invention, the outer shape of the heat conductive sheet is not limited to this, and is determined in accordance with the outer shape of the semiconductor element. It The heat conductive sheet 10 of the first to third examples,
Reference numerals 20 and 30 correspond to semiconductor elements having a generally rectangular outer shape, and are the most general shapes in that sense.

A heat conductive sheet (sheet-shaped resin base material)
Is a rectangle, in the heat conductive sheets 10, 20, and 30 of the first to third examples, the plurality of heat conduction paths 1 are formed on the main surface (2b) of the rectangular sheet-shaped resin base material. Although arranged in parallel to the parallel opposite sides on one side of the rectangular main surface (in a direction orthogonal to the parallel opposite sides on the other side), as shown in FIG. 1 may be arranged so as to be inclined with respect to the side of the rectangular main surface 2b of the sheet-shaped resin base material 2.

When the heat conductive sheet of the present invention is integrated with a semiconductor element, as described above, the surface 3a of the semiconductor element 3 with the plurality of heat conductive paths 1 separated from each other.
The sheet-shaped resin base material 2 intervenes in the gap between the adjacent heat conduction paths 1 (see FIG. 3), thereby forming a bonded state with sufficient bonding force (adhesive force). .
Therefore, the portion arranged on the main surface of the sheet-shaped resin base material on the side to be bonded to the semiconductor element surface in the heat conduction path has its diameter on the main surface of the sheet-shaped resin base material in advance during the production of the heat conduction sheet. It may be fixed so that a considerable part of the direction is embedded.

In the heat conductive sheet of the present invention, as described above, the sheet-shaped resin base material has an adhesive resin material, that is, a material which itself exhibits adhesiveness, or an adhesive property as it is. Although not shown, those exhibiting adhesiveness by heating and / or pressure are used. Examples of such an adhesive resin material include a thermoplastic resin that can be fused and / or pressure-bonded by heating and / or pressing, and a thermosetting resin that is thermoset by heating. Specific examples include thermoplastic polyimide resins, epoxy resins, polyetherimide resins, polyamide resins, silicone resins, phenoxy resins, acrylic resins, polycarbodiimide resins, fluororesins, polyester resins, polyurethane resins and the like. These resins may be used alone or in combination of two or more kinds. If the resin material is a thermoplastic resin, it is preferable in that rework is possible. On the other hand, a thermosetting resin is preferable in that it has an advantage of high adhesion reliability at high temperatures.

The heat conductive sheet of the present invention is directly attached to a semiconductor element, and its adhesive force is 0.2 to 2 k.
It is preferably gf / cm ² . In addition, the adhesive force is such that the heat conductive sheet is heated at a temperature of 300 ° C. and the pressure is 20 kg.
After adhering to the semiconductor element at f / cm ² , it is measured by peeling at 180 ° at room temperature. Therefore, it is preferable to select the material of the sheet-shaped resin base material so that such an adhesive force can be obtained according to the material of the semiconductor element and the like.

From the viewpoint of relaxing the stress generated inside the heat conductive sheet when the semiconductor element generates heat, the elastic modulus of the sheet-shaped resin base material is preferably 10 MPa to 20 GPa, and particularly preferably 10 MPa to 2 GPa. preferable. The elastic modulus of the sheet-shaped resin base material is determined by the resin material used, but when a thermosetting resin is used, it can be adjusted by selecting the curing conditions. The elastic modulus is, for example, a dynamic viscoelasticity measuring device (DMS21
0, manufactured by Seiko Instruments Inc.). The measurement conditions are a tensile mode, a constant frequency (10 Hz), and a temperature of 40 ° C. in one of the directions in which the surface of the heat conductive sheet expands. The thickness of the sample input at the time of measurement is 0.5 mm.

The heat-conducting material forming the heat-conducting path (heat-conducting wire) is not particularly limited, and a metal material such as copper, gold, aluminum, nickel, etc., or a metal material and a polyimide resin, an epoxy resin, Examples thereof include a mixture material with an organic material such as an acrylic resin and a fluororesin. Further, it is also possible to use carbon fiber having good thermal conductivity as it is. Preferred are metallic materials, of which copper is particularly preferred.

The wire diameter, pitch, etc. of the heat conducting path (heat conducting wire) may be appropriately selected according to the size, thermal characteristics, material, etc. of the partner (semiconductor element) to which the heat conducting sheet is adhered, Although not particularly limited, the wire diameter is 10 to 500 μm, preferably about 18 to 100 μm, and the pitch is 30 to 250.
μm, preferably about 50 to 200 μm. If the wire diameter of the heat conduction path is too small or the number thereof is too small (too large a pitch), the heat conductivity becomes poor, which is not preferable. vice versa,
If the wire diameter is too large or the number is too large (the pitch is too small), the strength of the heat conductive sheet and the adhesive strength to the mating member are reduced, which is not preferable.

The cross-sectional shape of the heat conduction path is not particularly limited,
A circular shape or a shape other than a circular shape, for example, a polygonal shape may be used, but a circular shape is preferable. In the present invention, the wire diameter of the heat conduction path (heat conductive wire) means the diameter of the circular cross section when a heat conductive wire having a circular cross section is used, and the cross section has a shape other than the circular shape. When the heat conductive wire of (3) is used, it means the diameter of a circle having the same area as the cross section other than the circle.

The coefficient of linear expansion of the heat conductive sheet of the present invention in the direction perpendicular to the thickness direction, that is, in the surface expansion direction is usually 2
-100 ppm, preferably 4-60 ppm. The coefficient of linear expansion is a value between the coefficient of linear expansion of the thermally conductive wire and the coefficient of linear expansion of the semiconductor element, and it is possible to prevent the thermal conductive sheet from being distorted or peeled in the thermal cycle test (TCT). TCT is 30 ℃ / 30min-80 ℃
/ 30 minutes as one cycle. The linear expansion coefficient can be set freely by changing the distribution configuration of the heat conduction sheet (the diameter of the heat conduction path, the pitch, etc.) and selecting the constituent material. The linear expansion coefficient can be measured using a TMA measuring device. The measurement condition is obtained as an average linear expansion coefficient at 25 ° C to 125 ° C.

In the heat conductive sheet of the present invention, the thickness of the sheet-shaped resin substrate (T in FIGS. 1, 4 and 5) is 25 to 1
The thickness is 000 μm, preferably 50 to 200 μm. When the thickness is less than 25 μm, the adhesive strength to the semiconductor element is reduced, which is not preferable. On the other hand, when it exceeds 1000 μm, the heat dissipation property is lowered, which is not preferable.

The heat conductivity of the heat conductive sheet of the present invention is preferably 1 to 15 W / mK. In addition, in this invention, the "heat conductivity" of a heat conductive sheet means the heat conductivity of the whole heat conductive sheet. The thermal conductivity is ASTE1
It is measured by the steady heat flow method according to 530E.

The method for producing the heat conductive sheet of the present invention is not particularly limited, but the following methods (1) to (4) are typical.

A plurality of heat conductive wires are attached in parallel to one main surface of the resin sheet, and the resin sheet is bent with the heat conductive wire being outside and then heated and / or pressed to form a resin sheet. A method of fixing the folded surfaces of the other main surface to each other. According to this method, the heat conductive sheet having the structure shown in FIG. 1 can be preferably manufactured. FIG. 8 shows a state in which the main surfaces of the resin sheet 52 on the side where the heat conductive wire 51 is not fixed are folded in the method. In this manner, the main surfaces of the resin sheet 52 on the side where the heat conductive wire 51 is not fixed are folded, and the heated and / or pressurized main surfaces are fused and / or pressure-bonded to each other. The heat conductive sheet having the structure shown in FIG. 1 can be easily manufactured. The sheet-shaped resin base material 2 is constituted by the resin sheet 52, and the heat conductive wire 51 serves as the heat conductive path 1.

In the work of fusing and / or crimping the surfaces of the resin sheet 52 where the heat conductive wires are not fixed by the above heating and / or pressurization, the heating temperature depends on the material of the resin base material. The temperature is usually (softening point of material) to about 250 ° C., and specifically 50 to 200 ° C., though it is appropriately selected. When using a thermosetting resin, it is preferable to heat at a temperature lower than the curing temperature. The applied pressure is preferably 0.1 to 10 MPa, more preferably 0.1 to 3 MPa.

A heat conductive wire is wound around the outer peripheral surface of a resin sheet held in a tubular shape with a predetermined gap between the wires, and the heat conductive wire is heated and / or pressed to form the wound heat conductive wire into a sheet. A resin sheet that is fixed to a resin base material, is held in the cylindrical shape, and has a thermally conductive wire wound around and fixed to its outer peripheral surface, and crushes it so that its internal space disappears substantially and heats it. And / or applying pressure to fix the folded surfaces of the inner peripheral surface of the resin sheet. According to this method, the heat conductive sheet having the structure shown in FIG. 4 can be preferably manufactured. FIG. 9 shows a process of crushing a resin sheet 52, which is held in a tubular shape and has a heat conductive wire 51 wound around and fixed to the outer peripheral surface thereof in the method, so that the internal space thereof is substantially lost. ing. In this way, the resin sheet 52, which is held in a tubular shape and has the heat conductive wire 51 wound around and fixed to the outer peripheral surface of the resin sheet 52, is crushed to eliminate the internal space of the resin sheet 52, and heating and / or pressurizing the resin sheet 52. 5
By fusing and / or pressure-bonding the folded surfaces of the inner peripheral surface of 2 to each other, the heat conductive sheet having the configuration shown in FIG. 4 can be easily manufactured.

The heating temperature and pressure in heating and / or pressurizing in this method are the same as those in heating and / or pressurizing in the above method.

In the above manufacturing method, the work of arranging (winding) the heat conductive wire on the main surface of the resin sheet (the outer peripheral surface of the resin sheet held in a tubular shape) is as shown in FIG. 7 (a). It is preferable to wind the resin sheet 52 around the core 40, and further to wind the heat conductive wire 51. According to the work, the work of winding the heat conductive wire on the outer peripheral surface of the resin sheet held in the cylindrical shape in the above manufacturing method can be efficiently performed. Furthermore, the heat-conducting wire rod 51, which is obtained by the work and is held in a cylindrical shape, is provided on the outer peripheral surface.
Is used in the method of, by cutting the wound resin sheet into a flat plate shape, or by cutting (cutting) the sheet body cut into a flat plate shape into an appropriate size, a plurality of sheets on one main surface It is possible to easily manufacture a resin sheet in which the heat conductive wire is fixed, and the folded surfaces of the other main surface are fixed by bending. The size of the cut (cut out) sheet body is appropriately determined according to the size of the semiconductor element used.

The core material may have various shapes such as a cylindrical shape and a prismatic shape, but the cylindrical shape is preferable from the viewpoint of workability in winding the heat conductive wire. Also,
The winding work of the heat conductive wire may be performed by rotating the core material, rotating the wire material, or rotating both. For example,
By using a known coil winding machine used in the manufacture of various metal wire coils, winding work can be performed efficiently.

When the heat conductive wire 51 is not sufficiently fixed to the resin sheet 52 due to the tightening force of the winding, as shown in FIG.
By pressing with the outer peripheral surface of the rotating roller 41 as shown in (b), the fixing force of the heat conductive wire on the resin sheet is increased, and the heat conductive wire 51 is embedded in the resin sheet 52 at a uniform depth. It can be fixed in the embedded state. The pressing force at this time is preferably about 0.01 to 10 MPa.

Further, heating may be performed in addition to the pressing, and the heating further improves the adhesion of the heat conductive wire to the resin sheet to the base material. The heating is performed by the roller 41
As the above, it can be carried out by incorporating a heater or using a roller with a heater in contact with a part of the surface of the roller. Further, the heating can be performed by placing the whole core material wound with the heat conductive wire in a heating environment.
The heating temperature is preferably about 50 to 200 ° C.

The roller is not particularly limited, but examples thereof include a metalizing roller and an induction heating roller. Further, from the viewpoint of releasability, the surface thereof may be coated with a fluororesin or a silicone resin.

A coil made of a heat conductive wire having an internal space capable of accommodating a resin sheet is prepared, and a resin sheet is inserted into the internal space of the coil, or resin is injected to mold the resin sheet, A method of fixing at least a part of a resin sheet to a coil made of a heat conductive wire by heating and / or pressurizing to integrate the resin sheet and the coil made of the heat conductive wire. According to the method, FIG.
The heat conductive sheet having the structure shown in can be suitably manufactured. Figure 10
Shows the operation of inserting the resin sheet 52 into the internal space of the coil made of the heat conductive wire 51 in the method. Thus, by heating and / or pressurizing
By fixing a part of the resin sheet 52 to the coil made of the heat conductive wire 51, the heat conductive sheet having the configuration shown in FIG. 5 can be easily manufactured. In the method, the method of winding the heat conductive wire for forming the coil of the heat conductive wire 51 is not particularly limited. For example, a known coil winding used in the manufacture of various metal wire coils. It can be done efficiently by using the machine. Further, the size of the coil may be arbitrarily determined depending on the semiconductor device used.

When the resin sheet is molded by injecting the resin, the method of injecting the resin is not particularly limited. For example, a method of injecting the resin into the hollow portion in the coil using a dispenser can be used. .

The mounting method of the semiconductor element having the heat conductive sheet of the present invention is not particularly limited, and a mounting method such as a face-down mounting by a flip chip method or a face-up mounting by a wire bonding method can be used. FIG. 11 is a cross-sectional view showing an example of the case where the heat conductive sheet of the present invention is attached to the semiconductor element 3 to form a semiconductor device. In the heat conductive sheet, only the heat conductive paths are hatched. In the example of the figure,
The semiconductor element 3 to which the heat conduction sheet (the heat conduction sheet 10 in the example of FIG. 1) is fixed is mounted on the circuit board 4 by the face-down mounting method by the flip chip method to form a semiconductor device. Although the semiconductor device circuit board is directly mounted in the figure, it may be mounted indirectly by interposing an anisotropic conductive film or a conductive resin therebetween. The heat conductive sheet may be fixed to the semiconductor element after the semiconductor element is mounted on the circuit board. The semiconductor element may be sealed with resin.

Hereinafter, the present invention will be specifically described with reference to examples, but the present invention is not limited to these examples.

[0041]

Example 1 A polycarbodiimide film (50 μm thick manufactured by Nitto Denko), which is a thermoplastic resin film, was wound around the outer circumference of a cylindrical core material made of aluminum rotatably supported. Next, using a coil winding machine, a 25 μmφ bare copper wire (manufactured by Furukawa Electric Co., Ltd.) as a heat conductive wire was wound around the outer periphery of the polycarbodiimide film at a wiring pitch of 100 μm. Next, an induction heating roller having a diameter of 30 mm, which is rotatably supported, is arranged so that its axis (rotation axis) is parallel to the axis (rotation axis) of the cylindrical core material, and the roller is set to 0. With a pressing force of 1 MPa, the temperature was raised to 120 ° C. and pressed toward the polycarbodiimide film, and in this state, the cylindrical core material (rotation speed: 50 rpm) and the roller (rotation speed:
The heat conductive wire was fixed to the resin by rotating (50 rpm) in opposite directions for 3 minutes. The obtained sheet was cut into a size of 20 mm × 10 mm. Then, bend it so that the heat conductive wire is on the outside, and
Curing was carried out at 30 ° C. for 30 minutes to prepare a heat conductive sheet. When the elastic modulus at 125 ° C. was measured using a dynamic viscoelasticity measuring device, it was 70 MPa. When the linear expansion coefficient was measured using a TMA measuring device, it was 60 ppm. This heat conductive sheet was attached to a semiconductor element at 150 ° C. and 6 MPa, and the semiconductor element was mounted by flip chip bonding to obtain a semiconductor device. When the thermal conductivity was measured using a measuring device based on the steady heat flow method, it was 8 W / mK.
Met.

Example 2 A silicone resin sheet (150 μm thick manufactured by Nitto Shinko Co., Ltd.), which is a heat conductive resin, was wound around the outer periphery of a cylindrical core material made of aluminum rotatably supported. Next, using a coil winding machine, a 25 μmφ bare copper wire (manufactured by Furukawa Electric Co., Ltd.) as a heat conductive wire was wound around the silicone resin sheet at a wiring pitch of 50 μm. Next, a rotatably supported metallizing roller having a diameter of 30 mm is arranged so that its axis (rotation axis) is parallel to the axis (rotation axis) of the cylindrical core material, and the roller is set to 0. .1
It is pressed against the silicone resin sheet with a pressing force of MPa, and in this state, the cylindrical core material (rotation speed: 50 rpm) and the roller (rotation speed: 50 rpm) are moved in opposite directions to each other.
The heat conductive wire was fixed to the resin by rotating for a minute. The obtained sheet was cut into a size of 20 mm × 10 mm. Then, it was bent so that the heat conductive wire was on the outside, and pressed again at 0.1 MPa to produce a heat conductive sheet. Using a dynamic viscoelasticity measuring device, 125
When the elastic modulus at ° C was measured, the elastic modulus of the heat conductive sheet was 10 MPa. It was 40 ppm when the linear expansion coefficient was measured using the TMA measuring device. After that, a semiconductor device was obtained in the same manner as in Example 1. When the thermal conductivity was measured using the same device as in Example 1, the thermal conductivity was 11 W / mK.

Example 3 A thermal conductive wire 25 μmφ bare copper wire (manufactured by Furukawa Electric Co., Ltd.) was set to 10 mm by a coreless winding machine (manufactured by Nittoku Engineering).
□, wound to a height of 3 mm. A polycarbodiimide resin was injected into the inner hollow portion of the obtained coreless coil with a dispenser and dried in an oven at 150 ° C. for 15 minutes to prepare a heat conductive sheet. When the elastic modulus at 125 ° C. was measured using a dynamic viscoelasticity measuring device, the elastic modulus of the heat conductive sheet was 20 MPa. When the linear expansion coefficient was measured using a TMA measuring device, it was 30 ppm. Using the obtained sheet coil, a semiconductor device was obtained in the same manner as in Example 1. When the thermal conductivity was measured using the same device as in Example 1, a value of 8 W / mK was obtained.

[0044]

According to the present invention, the semiconductor element has a high heat dissipation property, and is peeled from the surface of the semiconductor device.
It is possible to provide a heat conductive sheet in which problems such as cracks hardly occur. Further, according to the present invention, the heat conductive sheet can be manufactured by a simple process, and the heat conductive sheet can be provided at low cost.

[Brief description of drawings]

FIG. 1 is a schematic view of a first example of a heat conductive sheet of the present invention, FIG. 1 (a) is a top view, and FIG. 1 (b) is a side view.

FIG. 2 is a view in which the heat conductive sheet 10 of the first example is integrated with a semiconductor element.

3 is an enlarged schematic view of a joint portion between a heat conductive sheet and a semiconductor element in a cross section taken along the line AA in FIG.

4A and 4B are schematic views of a second example of the heat conductive sheet of the present invention, FIG. 4A is a top view and FIG. 4B is a side view.

FIG. 5 is a schematic view of a third example of the heat conductive sheet of the present invention, FIG. 5 (a) is a top view and FIG. 5 (b) is a side view.

FIG. 6 is an example of a heat conductive sheet of the present invention and is a top view. The plurality of heat conduction paths 1 are arranged so as to be inclined with respect to the sides of the rectangular main surface 2b of the sheet-shaped resin base material 2.

FIG. 7 shows an example of a method for manufacturing a heat conductive sheet of the present invention, wherein FIG. 7A is a step of winding a heat conductive wire around a base sheet, and FIG. 7B is pressure bonding of the heat conductive wire onto the base sheet. It is a figure which shows the process made.

FIG. 8 is a diagram showing an example of a method for manufacturing a heat conductive sheet of the present invention, showing a step of fixing the main surfaces of the resin sheet on the side where the heat conductive wire is not fixed.

FIG. 9 shows an example of a method for producing a heat conductive sheet of the present invention, in which a resin sheet held in a tubular shape and having a heat conductive wire rod wound and fixed on its outer peripheral surface has a substantially internal space. It is a figure which shows the process of crushing so that it may disappear in, and crimping.

FIG. 10 is a diagram showing an example of the method for manufacturing a heat conductive sheet of the present invention, showing a step of inserting a resin into the coil of the heat conductive wire.

FIG. 11 is a cross-sectional view showing an example of a case where a heat conductive sheet of the present invention is attached to a semiconductor element to form a semiconductor device.

[Explanation of symbols]

1 Heat Conduction Path (Heat Conductive Wire) 1a, 1b Heat Conduction Path Part on Main Surface of Sheet-shaped Resin Base Material 2 Sheet-shaped Resin Base Material 2a, 2b Main Surfaces of Sheet-shaped Resin Base Material 2c-1, 2c -2 Side surface of sheet-shaped resin base material 3 Semiconductor element 3a Surface of semiconductor element 4 Substrate 10 Thermal conductive sheet 20 of first example Thermal conductive sheet 30 of second example Thermal conductive sheet 40 of third example Core material 41 Roller 51 Heat-conducting wire 52 Resin sheet A Arrow indicating the thickness direction of the heat-conducting sheet T Thickness of sheet-shaped resin base material X Arrow indicating the longitudinal direction of the core material 40

   ─────────────────────────────────────────────────── ─── Continued front page    (72) Inventor Yuji Hotta             1-2 1-2 Shimohozumi, Ibaraki City, Osaka Prefecture Nitto             Electric Works Co., Ltd. F-term (reference) 5F036 AA01 BA23 BB21 BD21

Claims (11)

[Claims] 1. A sheet-shaped resin base material, and a plurality of heat conduction paths made of a heat conductive wire, wherein the plurality of heat conduction paths extend from one main surface of the base material to the side surface to the other side. A heat conductive sheet, which is continuous to the main surface of and is fixed to the base material. 2. A plurality of heat conduction paths are separated from each other, and
The heat conductive sheet according to claim 1, wherein the heat conductive sheets are arranged substantially in parallel. 3. A plurality of heat conduction paths are continuous from one main surface of the base material to the other main surface via a pair of opposite side surfaces. Or the heat conductive sheet according to 2. 4. The heat conducting sheet according to claim 1, wherein the plurality of heat conducting paths form a coil surrounding the sheet-shaped resin base material. 5. The heat conductive sheet according to claim 1, wherein the sheet-shaped resin base material is made of an adhesive material. 6. The heat conductive sheet according to claim 1, wherein the heat conductive wire is made of a metal material. 7. The heat conductive sheet according to claim 1, wherein the heat conductive wire is made of a carbon material. 8. A heat dissipation member for a semiconductor element.
The heat conductive sheet according to any one of to 7. 9. A first step in which a plurality of heat conductive wires are attached in parallel to one main surface of a resin sheet, and the resin sheet is bent, heated and / or applied with the heat conductive wires being outside. And a second step of fixing the folded surfaces of the other main surface of the resin sheet to each other by pressing. 10. A first step of winding a thermally conductive wire on the outer peripheral surface of a resin sheet held in a tubular shape with a predetermined gap between the wires, and the winding is performed by heating and / or pressurizing. The second step of fixing the heat conductive wire to the sheet-shaped resin base material, and the resin sheet held in the tubular shape and having the heat conductive wire wound around and fixed to the outer peripheral surface of the resin sheet. And a third step of fixing the folded inner surfaces of the resin sheet to each other by crushing, heating and / or pressing so as to substantially disappear. . 11. A coil made of a heat conductive wire, the first step of producing a coil having an internal space capable of accommodating a resin sheet described below, and an internal space of the coil made of the heat conductive wire, A second step of inserting a resin sheet or injecting a resin to form a resin sheet, and fixing at least a part of the resin sheet to a coil made of a heat conductive wire by heating and / or pressurizing. ,
A method of manufacturing a heat conductive sheet, comprising a third step of integrating a resin sheet and a coil made of a heat conductive wire.