JPH10284651A - Heat dissipating sheet and manufacture therefor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To suppress the generation of cracks and the separations by arranging a plurality of thermally conductive paths, made of thermally conductive material, in a state such that they penetrate a sheet base in the thickness direction thereof and their both end parts are exposed at the front and rear surface of the sheet base. SOLUTION: A plurality of thermally conductive paths 2, made of thermally conductive material, are arranged within a sheet base 4 in a state such that they penetrate the sheet base 4 in the thickness direction thereof and their both end parts 3 are exposed at the front and rear surfaces of the sheet base 4. Herein, the plurality of thermally conductive paths 2 are arranged within the sheet base 4 in a state that they are separated from each other. Further, the resin material forming the sheet base 4 is an adhesive material, and a heat- dissipating sheet 1 is applied directly to a semiconductor device 6, via no adhesive agent. Thus, it can have high heat-dissipating ability. Further, even when the heat of the semiconductor causes expansion or contraction of the thermally conductive paths, the sheet base becomes a buffer material to alleviate repeatedly generated internal stresses, so that the generation of cracks and the separations can be suppressed.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a heat dissipation sheet, which is one of components constituting a semiconductor device and is used by being mounted on a semiconductor element, and a method of manufacturing the same.

[0002]

2. Description of the Related Art In recent years, the package of a semiconductor device has been changed from a package in which a semiconductor element is sealed with a resin to a package in which the semiconductor element is directly mounted on a circuit board without being sealed with a resin. Note that the semiconductor element referred to here is also called a bare chip, and indicates a semiconductor element at a stage where a circuit is formed on a crystal substrate (wafer) and cut out.

In these types of packages (semiconductor packages), the degree of integration of semiconductor elements has increased due to technological innovation in the semiconductor field, and the heat generated in the semiconductor elements has increased as the dimensions of the semiconductor elements have increased. Is increasing. Therefore, heat generated during operation of the semiconductor element is accumulated in the semiconductor device, and may exceed the junction temperature of the semiconductor element, resulting in malfunction. For this reason, improvement in heat resistance and heat dissipation has been an issue.

[0004] In order to solve these problems, in the above semiconductor package, the thermal conductivity of the semiconductor element and the sealing resin is extremely low.
It has been proposed to stack a metal foil on a die pad to which a semiconductor element is fixed, and to radiate heat using the metal foil.

[0005]

However, in this case, due to the imbalance of constituent materials in the thickness direction of the semiconductor device,
That is, since the linear expansion coefficient of a metal foil is generally larger than that of a semiconductor element or a die pad, repeated stress is generated in the metal foil due to repeated heat generation of the semiconductor element, and eventually, the metal foil peels off, There is a problem that cracks occur in the metal foil due to fatigue.

Japanese Patent Application Laid-Open No. 63-187652 discloses that a metal foil is bonded to one or both sides of a semiconductor device via an adhesive. However, in this method, the adhesive layer formed by bonding generally has a large hygroscopic property, so that rapid expansion of moisture occurs at the time of soldering, and voids or peeling occurs at the interface between the metal foil and the adhesive layer. There is a problem.

[0007] Further, in Japanese Patent Application Laid-Open No. H8-17855,
Although a semiconductor device in which the surface of a sealing resin is covered with a metal foil is disclosed, even in this case, the problem of peeling or cracking of the metal foil has not been solved.

An object of the present invention is to provide a heat dissipation sheet which exhibits high heat dissipation to a semiconductor element, hardly peels off from the surface of a semiconductor device, and hardly causes cracks, and a method of manufacturing the same.

[0009]

The present invention has the following features.

(1) In a sheet base made of a resin material, a plurality of heat conduction paths made of a heat conductive material penetrate the sheet base in a thickness direction, and are provided on both sides of the sheet base. A heat dissipation sheet for mounting a semiconductor element, which is arranged in a state where the portion is exposed.

(2) The elastic modulus of the sheet substrate is 10M
The heat dissipation sheet according to the above (1), which has a Pa to 20 GPa.

(3) The heat-dissipating sheet according to the above (1), wherein the heat-conducting paths are arranged in the sheet substrate in a state of being isolated from each other.

(4) The heat-dissipating sheet according to the above (1), wherein a coating layer made of a material different from the material constituting the sheet base material is formed on the surface excluding both ends of the heat conduction path.

(5) The heat dissipation sheet according to the above (4), wherein at least one of the sheet substrate and the coating layer is formed from an adhesive material.

(6) The heat radiating sheet according to the above (1), which is mounted on a semiconductor element whose entire surface except for the surface on which the heat radiating sheet is to be mounted is sealed with a resin.

(7) The heat dissipation sheet according to the above (1), wherein the heat conductive material is a metal material.

(8) The heat dissipation sheet according to the above (1), wherein at least one end of at least one heat conduction path protrudes from the surface of the sheet substrate.

(9) A step of forming at least a resin layer on a thin wire made of a heat conductive material, a step of winding the thin wire on which the resin layer is formed around a core material, and heating and / or pressurizing the wound coil. And bonding the resin layers together by fusing and / or crimping to form a wound coil block, and a plane intersecting the winding direction of the wound fine wire at an angle to the sheet surface. And cutting out the heat radiation sheet from the coil coil block.

(10) The method for manufacturing a heat-dissipating sheet according to the above (9), further comprising a step of coating the fine wires with a material different from the material constituting the resin layer before forming the resin layer.

[0020]

The heat dissipation sheet of the present invention has a structure in which a plurality of heat conduction paths penetrate in a thickness direction in a sheet base made of a resin material, and both ends are exposed on the front and back surfaces of the sheet base. ing. Therefore, it can have high heat dissipation, and furthermore, when the heat conduction path expands or contracts due to the heat dissipation of the semiconductor element, the sheet base acts as a buffer material to reduce the internal stress repeatedly generated in the heat conduction path. Alleviates fatigue of the heat conduction path.

According to the manufacturing method of the present invention, the heat radiating sheet is manufactured by cutting out the wound coil block formed by heating the wound coil or the like. Therefore, it is not necessary to form a through hole for the heat conduction path in the sheet substrate, and the labor for filling the through hole with the heat conductive material can be omitted.

Further, in the heat dissipation sheet of the present invention, a coating layer made of a material different from the material constituting the sheet base material can be formed on the surface excluding both end portions of the heat conduction path. By using the manufacturing method, the coating layer can be easily formed, and the material of the coating layer and the thickness of the coating layer can be easily changed. Therefore, the distribution configuration of the heat radiating sheet can be freely designed, and the linear expansion coefficient in the surface direction of the heat radiating sheet can also be freely set.

[0023]

Next, the present invention will be described in detail with reference to the drawings. FIG. 1 is a view showing an example of a heat dissipation sheet of the present invention, wherein FIG. 1 (a) is a top view and FIG. 1 (b) is a sectional view. As shown in FIGS.
Is a heat dissipation sheet for mounting a semiconductor element, which is a member for constituting a semiconductor device. In a sheet substrate 4 made of a resin material, a plurality of heat conduction paths 2 made of a heat conductive material are formed.
Penetrates the sheet substrate 4 in the thickness direction, and has both end portions 3
Are exposed on the front and back surfaces of the sheet substrate 4. In the example of FIG. 3A, the plurality of heat conduction paths 2 are arranged in the sheet base material in a state where they are isolated from each other. The resin material forming the sheet base 4 is an adhesive material. In the example of FIG. 2B, the heat radiation sheet 1 is directly attached to the semiconductor element 6 without using an adhesive.

FIGS. 2A and 2B show another example of the present invention. FIG. 2A is a top view, and FIG. 2B is a sectional view.
In the example of the figure, on the surface excluding both ends 3 of the heat conduction path 2,
A coating layer 5 is formed, and the rest is the same as the example of FIG. The material forming the coating layer 5 is different from the material forming the sheet base material.

With the structure shown in FIGS. 1 and 2, when the semiconductor element generates heat, the stress applied to the heat radiating sheet can be reduced, and peeling and cracking of the heat radiating sheet can be suppressed. Furthermore, since it can be attached to a semiconductor element without using an adhesive, the problem caused by the adhesive described above can be solved.

The heat radiation sheet of the present invention is directly mounted on a semiconductor element, and therefore, the resin material forming the sheet substrate is preferably an adhesive material. In addition,
The term “adhesiveness” as used herein refers to adhesiveness to a semiconductor element, and means that the adhesive strength is 200 g / cm to 2 kg / cm. In addition, the measurement of the adhesive force was performed by using a resin material of 300
After heating to about ° C. and pasting with a compression force of 20 kg / cm ² , the peeling is performed at room temperature by 180 ° peel.

The term "adhesive material" means not only a material that exhibits adhesiveness as it is, but also does not exhibit adhesiveness as it is, but can be adhered by heating and / or pressing. Also referred to as For example, a thermoplastic resin that is fused and / or pressed by heating and / or pressurization, and a thermosetting resin that is thermoset by heating.

As the resin material forming the sheet substrate,
Materials and the like used for general resin sheets can be used. However, if the resin material is an adhesive material, thermoplastic polyimide resin, epoxy resin, polyetherimide resin, polyamide resin, silicone resin, phenoxy resin, acrylic resin, polycarbodiimide resin, fluororesin, polyester resin, polyurethane resin And the like may be appropriately selected from these depending on the purpose. These resins may be used alone or in combination of two or more.

If the resin material exemplified above is a thermoplastic resin, it is preferable in that rework can be performed. On the other hand, a thermosetting resin is preferable in that it has an advantage that the bonding reliability at high temperatures is improved. Whether a thermoplastic resin or a thermosetting resin is used as the resin material for forming the sheet base material may be appropriately determined according to the use of the heat radiation sheet.

The resin materials exemplified above include
Add various fillers, plasticizers or rubber materials as appropriate
May be. As the filler, for example, SiO_Two, Al
_TwoO _ThreeAs the plasticizer, for example, TCP (tric acid phosphate)
Resyl), DOP (dioctyl phthalate), rubber materials
For example, NBS (acrylonitrile butadienego)
), SBS (polystyrene-polybutylene-polystyrene)
Len) and the like.

The surface excluding both ends of the heat conduction path is shown in FIG.
It is preferable to form the same coating layer as described above. By forming the coating layer, the distribution configuration of the heat radiating sheet can be changed in the plane direction, so that the linear expansion coefficient of the heat radiating sheet can be easily set. Further, by forming the coating layer, the adhesiveness between the sheet substrate and the heat conduction path, the strength of the obtained heat dissipation sheet, and the heat resistance can be improved.

When a coating layer is formed on the heat conduction path, at least one of the sheet substrate and the coating layer is preferably formed of an adhesive material for the above-mentioned reason. The material that forms the coating layer (hereinafter “coating material”)
That. ) May be insulating or non-insulating. If an insulating and adhesive material is used as the coating material, the same materials as those exemplified above as the resin material for forming the sheet substrate can be used.
However, it is necessary to use a resin material different from the resin material forming the sheet base material.

By appropriately selecting and combining the resin material and the coating material forming the sheet base material, the effect produced by the above-mentioned coating layer can be made more preferable. For example, in order to improve the adhesiveness between the sheet substrate and the heat conduction path, it is preferable to select a polyetherimide resin as a resin material forming the sheet substrate and a polyamide resin as a coating material. In order to improve the strength of the heat radiation sheet, it is preferable to select a polyimide resin as a resin material forming the sheet base material and an epoxy resin as a coating material. In order to improve the heat resistance of the heat radiating sheet, it is preferable to select a polyimide resin or a polycarbodiimide resin as a resin material forming the sheet base material, and to select a polyester resin or a polyurethane resin as a coating material.

The elastic modulus of the sheet substrate is preferably set to 10 MPa to 20 GPa, more preferably 10 MPa to 2 GPa, from the viewpoint of relaxing the stress generated inside the heat radiating sheet when the semiconductor element generates heat. When forming a coating layer on the heat conduction path, the elastic modulus of the coating layer is preferably set to 10 MPa to 30 GPa, more preferably to 1000 MPa to 20 GPa.

The modulus of elasticity of the sheet substrate and the modulus of elasticity of the coating layer are preferably set so that one is at least 10 times as large as the other. More preferably, the elastic modulus is set to be 10 times or more the elastic modulus of the coating layer. With this setting, the stress generated inside the heat dissipation sheet can be more preferably alleviated, and the reliability of the heat dissipation sheet can be improved.

The elastic modulus of the sheet substrate or the coating layer is set as follows.
What is necessary is just to set suitably by selection of a material, addition of a filler, a rubber material, etc. In addition, what is necessary is just to use the thing similar to the above-mentioned filler and rubber material as a filler and a rubber material. When the resin material or the coating material forming the sheet base is a thermosetting resin, a method of selecting curing conditions is also adopted.

The heat conduction path is formed of a heat conductive material, and is installed with the sheet base material penetrated in the thickness direction and both ends thereof exposed to the sheet base material. Is fine. The heat conduction path may be in a state of being in contact with another heat conduction path when installed in the sheet substrate, or may be in a state of being isolated from each other. In the present invention, “thermal conductivity” means that the thermal conductivity is 0.1 to 0.9.
It means that it is 5.

As the heat conductive material, for example, copper, gold,
Examples include metal materials such as aluminum and nickel, and mixtures of these metal materials with organic materials such as polyimide resins, epoxy resins, acrylic resins, and fluororesins. The heat conductive material may be appropriately selected depending on the use of the heat radiation sheet of the present invention, but a metal material is preferable in terms of heat conductive characteristics, and copper is particularly preferable.

The size and number of the heat conduction paths may be appropriately selected according to the use of the heat radiation sheet. For example, in the case of a cylindrical heat conduction path as shown in FIG.
It is preferable that they are arranged with a pitch of about 30 μm and about 30 μm. If the heat conduction path is too small or the number is too small, the heat conductivity is inferior, which is not preferable. Conversely, if the heat conduction paths are too large or too many, the strength of the heat radiating sheet will be poor.
The shape of the heat conduction path may be any shape as long as such a problem does not occur, and may be a shape other than the column shape shown in FIG. 1, for example, a polygonal column shape.

The direction of penetration of the heat conduction path is not limited to the thickness direction of the sheet substrate in a strict sense as shown in FIG. 1, that is, the direction perpendicular to the sheet substrate surface, but the direction perpendicular to the sheet substrate surface. The direction may be an angle with respect to.

FIG. 3 is a sectional view showing another example of the heat radiation sheet of the present invention. As shown in the figure, at least one end 33 of at least one heat conduction path 32 protrudes from the surface of the sheet base 34. In the example shown in the figure, a semiconductor element 36 is attached to one surface of a sheet base 34. All the ends 33 of the heat conduction path 32 on the opposite side of the semiconductor element project hemispherically from the surface of the sheet base 34. 35 is a coating layer. Although not shown, the shape of the end portion 33 may be a shape in which the hemispherical portion in the figure is further expanded in the plane direction beyond the diameter of the heat conduction path 32, or may be a columnar shape or a square shape. It may be columnar. By protruding the end of the heat conduction path in this way, the exposed area of the heat conduction path can be enlarged, so that the heat radiation of the heat radiation sheet of the present invention can be further enhanced.

As a method of projecting the end of the heat conduction path from the sheet substrate surface in a cylindrical shape, for example, there is a method of selectively removing the surface of the obtained heat radiation sheet. Specific examples include wet etching with an organic solvent, plasma etching, dry etching with an argon ion laser, a KrF excimer laser, and the like. These may be removed alone or in combination. The above-mentioned organic solvent is appropriately selected depending on the kind of the insulating material and the coating material to be the sheet substrate. For example, dimethylacetamide, dioxane, tetrahydrofuran, methylene chloride and the like can be mentioned. As a method of projecting the end of the heat conduction path in a hemispherical shape as shown in FIG. 3, there is a method of projecting by electroless plating.

As a method of depressing the end of the heat conduction path from the surface of the sheet substrate, there is a method of selectively removing only the heat conduction path of the obtained heat radiation sheet. Specific examples include chemical etching using an acid or an alkali.

The thermal expansion sheet of the present invention has a linear expansion coefficient of 2 ppm in the direction perpendicular to the thickness direction, that is, in the plane extending direction.
It is sufficient if it is 100 ppm, and it is preferably 4 ppm to 30 ppm. With this setting, the coefficient of linear expansion becomes a value between the coefficient of linear expansion of the thermally conductive material and the coefficient of linear expansion of the semiconductor element, and it is possible to prevent the heat dissipation sheet from being distorted or peeled off in the TCT test. The coefficient of linear expansion can be set freely by changing the distribution configuration of the heat radiation sheet or by selecting the constituent material.

The thickness of the heat radiation sheet of the present invention is from 25 μm to
It may be set to 1000 μm, and 50 μm to 40 μm.
It is preferably set to 0 μm. 25 μm thick
If it is less than this, the adhesive strength to the semiconductor element decreases, which is not preferable. Conversely, if the thickness exceeds 1000 μm, the heat radiation property is undesirably reduced.

The mounting method of the semiconductor element to which the heat radiation sheet of the present invention is attached 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. 4 is a cross-sectional view showing an example in which a semiconductor device is formed by mounting the heat dissipation sheet of the present invention on a semiconductor element. In the heat dissipation sheet 41, only the heat conduction path is hatched. In the example shown in the figure, the semiconductor device 46 to which the heat radiation sheet 41 is fixed is mounted on a circuit board 48 by a face-down mounting method by a flip chip method, thereby forming the semiconductor device 40. 47 is a circuit wiring. Although the semiconductor element 46 is directly mounted on the circuit board 48 in FIG. 3, it may be mounted indirectly with an anisotropic conductive film or conductive resin interposed therebetween. The heat radiation sheet 41 may be fixed to the semiconductor element 46 after the semiconductor element 46 is mounted on the circuit board. The semiconductor element 46 may be sealed with a resin.

FIG. 5 is a sectional view showing another example in which a semiconductor device is formed by mounting the heat dissipation sheet of the present invention on a semiconductor element. In the heat dissipation sheet 51, only the heat conduction path is hatched. In the example shown in the figure, the semiconductor device 56 to which the heat radiation sheet 51 is fixed is mounted on a circuit board by a face-up mounting method using a wire bonding method to form the semiconductor device 50. Semiconductor element 5
6 is electrically connected to a ground lead 58 via a wire 57. The entire surface of the semiconductor element 56 except for the surface on which the heat radiation sheet 51 is to be mounted is sealed with a resin 59. Note that the heat radiation sheet 51 may be attached after the semiconductor element 56 is mounted, or before the resin sealing.
Either during or after sealing may be performed. In any case, the heat radiating sheet 51 has a heat radiating surface exposed to the atmosphere.

As the sealing resin for the semiconductor element, various resins generally used in the semiconductor field can be used. Specifically, a resin obtained by adding an appropriate filler as needed to a heat-resistant resin such as an epoxy resin or a polyimide resin may be used. Examples of the material of the wire used in the wire bonding method include various metals, for example, aluminum, gold, copper, and an organic material containing a metal powder (for example, silver).

FIG. 6 is a view showing a method of manufacturing a heat radiation sheet of the present invention and a heat radiation sheet manufactured by the method. As shown in FIGS.
Is a step of forming a resin layer 66 on a thin wire 65 made of a heat conductive material, and forming the thin wire 65 on which the resin layer 66 is formed by:
A step of winding the core coil 67, a step of heating and / or pressurizing the coil, and a step of fusing and / or pressing the resin layer 66 to form a unitary coil coil block 68; A flat surface that intersects at an angle with the winding method of the thin wire 65 is used as a cutting surface, and the heat dissipation sheet 61 is cut out from the coil coil block 68 so that the cut surface becomes a sheet surface. .

The example of FIG. 9A shows a state immediately before cutting out the heat radiation sheet from the coil block 68. Only the resin layer 66 is formed on the fine wire 65. The shape of the core 67 is a quadrangular prism. The fine wire 65 is wound substantially perpendicularly to the axial direction (longitudinal direction) of the core material 67 around the core material 67 and is finely filled. The cutting out of the heat radiation sheet 61 is performed by a blade 69. Blade 69 is heartwood 67
It is installed in parallel to the axial direction of. Although not shown, the blades 69 are inserted in the axial direction of the core at intervals corresponding to the thickness of the heat radiation sheet.

In the example shown in FIG. 5B, the heat radiation sheet 61 cut out from the coil block 68 by a blade 69 is used.
Is shown. The resin layer 66 formed on the fine wire 65 serves as a sheet base 64 of the heat radiation sheet 61.
Are heat conduction paths 62. The heat conduction path 62 penetrates the sheet base 64 in the thickness direction, and is installed in a state where both ends thereof are exposed on the front and back of the sheet base 64,
Isolated from each other. Although not shown, the heat radiation sheet 61 is further reduced in thickness as necessary, cut to fit the size of the semiconductor element, and mounted on the semiconductor element.

As the material of the fine wire used in the manufacturing method of the present invention, the above-mentioned heat conductive material may be used. The diameter of the thin wire may be the same as the diameter of the heat conduction path described above.
Here, if the material of the fine wire is a metal material, the wire diameter is appropriately selected depending on the use of the heat radiation sheet of the present invention.
It is preferably set to about 0 to 200 μm,
More preferably, it is set to about 100 μm. The cross-sectional shape of the thin wire is not limited to the round shape as shown in FIG. 6 and may be appropriately determined according to the use of the heat radiation sheet and the like.

As a method for forming a resin layer on a fine wire, known methods can be used, for example, solvent coating (wet coating), melt coating (dry coating).
And the like. The thickness of the resin layer is appropriately selected depending on the desired pitch of the heat conduction paths in the obtained heat dissipation sheet, that is, the number per unit area, but is preferably 10 μm to 10 μm.
0 μm, and more preferably 20 μm to 50 μm.

In the example of FIG. 6, only the resin layer is formed on the fine wire. However, if the heat radiation sheet shown in FIG. 2 is to be manufactured, a material different from the resin layer must be formed before the resin layer is formed. May be formed in the same manner as in FIG. As a method for forming the coating layer, a method similar to the method for forming the resin layer described above can be used.

The winding may be performed by winding at least a thin wire on which a resin layer is formed around a core material in a roll shape with a predetermined width and thickness, and it is uniform in the width direction (axial direction of the core material) and the thickness direction. It is preferable that the packing is performed so as to be finely packed. The number of fine wires used for the winding may be one or a plurality. In the case of a plurality of wires, a plurality of fine wires may be simultaneously drawn out and wound. The winding direction is generally a direction substantially perpendicular to the axis of the core material as shown in FIG. 6, but is not particularly limited.

The shape of the core material is not limited to the one shown in FIG. 6 as a square pillar, but may be a polygonal pillar or a cylinder other than the square pillar. The material constituting the core material may be any material that has little deformation, deterioration, etc. in the manufacturing process of the heat radiation sheet, and specifically, polyimide resin, polycarbonate resin, epoxy resin, BT resin (manufactured by Mitsubishi Gas Chemical Company), etc. Is mentioned. Various fillers may be added to these resins depending on the application. Examples of the fillers include SiO ₂ and Al ₂ O ₃ .

The temperature for heating the winding coil may be appropriately selected according to the type of the resin material forming the resin layer. The softening point of the resin material is about 300 ° C., preferably about 5 ° C.
What is necessary is just to set to about 0 degreeC-300 degreeC. When a thermosetting resin is used as the resin material, heating may be performed at a temperature lower than the curing temperature. The pressure for pressurizing the wound coil is preferably 1 kg / cm ^{2 to} 100 kg / c.
m ² , more preferably 2 kg / cm ^{2 to} 20 kg / cm
^It is better to set to about ² .

The heat-dissipating sheet is cut out from the coil coil block only if the plane intersecting the direction of the wound fine wire at an angle is the sheet surface. That is, the direction in which the winding coil is cut may be different from the direction in which the thin metal wire is wound.
The direction is not a direction perpendicular to the axial direction of the core material. Since the cut interval corresponds to the thickness of the obtained heat radiation sheet, the thickness of the sheet can be arbitrarily set by changing the interval at which the blade is inserted. According to such a manufacturing method, a heat radiation sheet having a thickness of 50 μm or more can be easily formed.

If a heat conduction path is formed at an angle with respect to the direction perpendicular to the surface of the sheet substrate, the direction in which the blade is inserted should be at a predetermined angle with respect to the direction perpendicular to the direction in which the thin metal wire is wound. (Usually, a direction that forms a predetermined angle with the axial direction of the core material). By doing so, the heat conduction path is arranged at a predetermined angle with respect to the vertical direction of the sheet substrate surface.

If a recording material layer is provided on the surface of the heat radiating sheet of the present invention and solid identification information is recorded on the recording material layer, the heat radiating sheet of the present invention can be used as an information recording label, which is preferable. It becomes an aspect.

[0061]

【Example】

Example 1 The heat radiation sheet shown in FIG. 1 was actually manufactured according to the production process shown in FIG. 6, and the obtained heat radiation sheet was evaluated.

As shown in FIG. 6, a copper wire having a diameter of 35 μm (length: 100,000 m) was coated on a polyetherimide resin (Ultem-1000, manufactured by Nippon Polyimide, with an elastic modulus of 1000 MP).
a) was coated. Note that the thickness of the resin layer was set to 25 μm. Next, the core material (plastic, square pillar:
(30 mm x 30 mm x 300 mm), the copper wire on which this resin layer is formed is uniformly and finely packed in a predetermined width and thickness in the width and thickness directions, and is substantially perpendicular to the axis of the core material. Rolled up. In this case, a device for winding a general coated electric wire in a roll shape was used.

While the obtained coil was heated to about 300 ° C., pressure (60 kg / cm ² ) was applied to fuse the polyetherimide resin, and the coil was cooled to room temperature to form a coil coil block. . Next, the cutting tool was inserted into the winding coil block at an interval of 10 mm in the axial direction of the core material, and the length was 300 mm ×
A sheet of about 120 mm × about 10 mm (length × width × thickness) was cut out. The cut-out sheet is further sliced by a knife, and is 300 mm × 30 mm × 0.1 mm
A heat radiating sheet (length × width × thickness) was obtained. The heat dissipation sheet had an elastic modulus of 1100 MPa and a coefficient of linear expansion of 60 ppm. This heat radiation sheet is further cut to obtain a semiconductor element (5.7).
(mm × 5.7 mm × 5.7 mm), and the semiconductor element was mounted on a circuit board in the same manner as in FIG. 4 to obtain a semiconductor device.

Example 2 Except that the diameter of the copper wire was 100 μm and the length was 10,000 m,
A heat dissipation sheet was prepared in the same manner as in Example 1, and mounted on a circuit board in the same manner to obtain a semiconductor device.

Example 3 The heat radiation sheet produced in Example 1 was attached to a similar semiconductor element and mounted by a wire bonding method as shown in FIG. 5 to obtain a semiconductor device. Note that gold was used as the material of the wire, and epoxy resin was used as the sealing resin.

Example 4 A copper wire having a diameter of 35 μm was coated with a fluororesin (PTFE resin, elastic modulus 10 MPa) so as to have a thickness of 5 μm, and further coated with a polyetherimide resin so as to have a thickness of 25 μm. . Next, the same processing as in Example 1 was performed to produce a heat dissipation sheet, and a semiconductor device similar to that in Example 1 was obtained.

Comparative Example 1 The same semiconductor element as in Example 1 was flip-chip mounted on a circuit board. However, the heat dissipation sheet is not attached to the semiconductor element.

Comparative Example 2 As shown in FIG. 7, a radiation fin 71 made of black alumite was used.
The semiconductor device was affixed to the same semiconductor element as in Example 1 and mounted on a circuit board (not shown) to obtain a semiconductor device.

Evaluation of Examples and Comparative Examples A heat radiation test was performed using the semiconductor devices obtained in Examples 1 to 4 and Comparative Examples 1 and 2. Specifically, the power consumption is 1 W,
Thermal resistance was measured at a wind speed of 4 m / sec. Further, each semiconductor device has a temperature of -50 ° C./5 min.
A TCT test was performed at 0 ° C. for 5 minutes, and the number of peelings was measured. Table 1 shows the results.

[0070]

[Table 1]

As is clear from Table 1, in Comparative Example 2,
Many peeling of the heat radiating sheet occurred, and in Comparative Example 1, there was a problem in heat radiation as compared with the Examples. On the other hand, in Examples 1 to 4, good results were obtained for all the evaluation items.

[0072]

According to the heat radiating sheet of the present invention, cracks and peeling from the semiconductor device due to heat generation of the semiconductor element are suppressed. Therefore, according to the present invention, a highly reliable heat radiation sheet can be provided. Furthermore, according to the manufacturing method of the present invention, since the heat radiation sheet can be manufactured by a simple process, the heat radiation sheet can be provided at low cost.

[Brief description of the drawings]

FIG. 1 is a view showing an example of a heat dissipation sheet of the present invention.

FIG. 2 is a view showing another example of the heat dissipation sheet of the present invention.

FIG. 3 is a cross-sectional view showing another example of the heat radiation sheet of the present invention.

FIG. 4 is a cross-sectional view showing an example of a case where a semiconductor device is formed by mounting a heat dissipation sheet of the present invention on a semiconductor element.

FIG. 5 is a cross-sectional view showing another example in which a semiconductor device is formed by mounting a heat dissipation sheet of the present invention on a semiconductor element.

FIG. 6 is a view showing a production method of the present invention and a heat dissipation sheet produced by the production method.

FIG. 7 is a diagram showing a conventional semiconductor device.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Heat dissipation sheet 2 Heat conduction path 3 End part (both ends) 4 Sheet base material 5 Coating layer 6 Semiconductor element

Claims (10)

[Claims] 1. A plurality of heat conduction paths made of a heat conductive material penetrate a sheet base in a thickness direction in a sheet base made of a resin material, and are provided on both sides of the front and back surfaces of the sheet base. A heat radiation sheet for mounting a semiconductor element, which is arranged in a state where the semiconductor device is exposed. 2. An elastic modulus of the sheet base material is 10 MPa or more.
The heat dissipation sheet according to claim 1, wherein the heat dissipation sheet has a pressure of 20 GPa. 3. The heat-dissipating sheet according to claim 1, wherein the heat-conducting paths are arranged in the sheet substrate in a state of being isolated from each other. 4. The heat dissipation sheet according to claim 1, wherein a coating layer made of a material different from a material forming the sheet base material is formed on a surface excluding both end portions of the heat conduction path. 5. At least one of the sheet substrate and the coating layer is formed of an adhesive material.
Heat dissipation sheet as described. 6. The heat radiating sheet according to claim 1, wherein the heat radiating sheet is mounted on a semiconductor element which is entirely sealed with resin except for the surface on which the heat radiating sheet is to be mounted. 7. The heat conductive material is a metal material.
Heat dissipation sheet as described. 8. The heat dissipation sheet according to claim 1, wherein at least one end of at least one heat conduction path protrudes from a surface of the sheet substrate. 9. A step of forming at least a resin layer on a thin wire made of a heat conductive material, a step of winding the thin wire on which the resin layer is formed on a core material, and heating and / or heating the wound coil.
Alternatively, a step of forming a wound coil block by applying pressure and fusing and / or crimping the resin layers together to form a wound coil block, and a plane intersecting the winding direction of the wound fine wire at an angle to the sheet surface. A step of cutting out the heat radiating sheet from the wound coil block. 10. The method for manufacturing a heat radiation sheet according to claim 9, further comprising a step of coating the fine wires with a material different from a material forming the resin layer before forming the resin layer.