JPH0917923A - Heat condition sheet - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a heat conduction sheet which does not damage a semiconductor element during fixing, realizes good contact between a heat sink body which is a heat dissipation material and a semiconductor element and brings about effective heat conduction and good heat dissipation effect. SOLUTION: The title heat conduction sheet is provided with a silicone gel layer 2 whose heat conductivity is 1×10<-3> to 5×10<-3> cal/cm.sec. deg.C and consistency is 10 to 80 in both sides of a supporter 1 whose heat conductivity is 1×10<-4> cal/cm.sec. deg.C or more.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention is useful for efficiently connecting semiconductor elements such as ICs, LSIs and CPUs to heat dissipation members in computers, word processors, and particularly notebook or laptop type information processing equipment. It relates to a heat conductive sheet.

[0002]

2. Description of the Related Art In recent years, information processing equipment such as computers and word processors have come to be preferred to be portable and thin. In this type of information processing equipment, recently, a semiconductor element having a power consumption of more than 2 W has appeared. In such a semiconductor device with high power consumption, the performance of the semiconductor device is adversely affected unless some heat dissipation means is provided. Therefore, conventionally, a method of directly contacting a heat sink body with a semiconductor element as a heat dissipation member,
A method of applying grease between the heat sink body and the top surface of the semiconductor element, a method of sandwiching a heat radiation rubber sheet between the heat sink body and the top surface of the semiconductor element, and the like have been adopted.

[0003]

However, in the above method, the semiconductor element may be damaged during mounting, and since the heat sink body and the semiconductor element are rigid bodies, point contact is made and efficient heat conduction is achieved. No heat dissipation effect is obtained. This method causes unevenness in the grease application state due to changes in grease viscosity due to temperature differences and the control state of the coating device, and efficient heat dissipation cannot be achieved unless the heat sink body side is pressed down with a strong force.
In this method, unless the rubber sheet is pressed down with a strong force from the side of the heat sink, a good heat radiation effect cannot be obtained as if the rubber sheet and the top surface of the semiconductor element are in point contact. Therefore, an object of the present invention is to prevent the semiconductor element from being damaged at the time of mounting, to ensure good contact between the heat sink body which is a heat dissipation member and the semiconductor element, and to obtain efficient heat conduction and good heat dissipation effect. And to provide a heat conductive sheet.

[0004]

The heat conductive sheet of the present invention has a heat conductivity of 1 × 10 ^{−3 on} both sides of a support having a heat conductivity of 1 × 10 ⁻⁴ cal / cm · sec · ° C. or more. ~ 5 × 10 ^-3 cal / cm ・ sec ・ ℃
And a silicone gel layer having a consistency of 10 to 80 is provided, the silicone gel layer having a thickness of 0.05 to 1.0 mm, and a plastic film laminated on the surface of the silicone gel layer. That is preferable. In this heat conductive sheet, the support body improves the adhesiveness and handleability and directly contributes to the improvement of the heat conductivity, and the silicone gel layer enhances the adhesiveness to the semiconductor element and the heat sink body, and the efficient heat conduction is achieved. And give a good heat dissipation effect.

[0005]

BEST MODE FOR CARRYING OUT THE INVENTION Hereinafter, the present invention will be described in more detail with reference to FIG. FIG. 1 (a),
(B) is a longitudinal sectional view showing different embodiments of the heat conductive sheet of the present invention, and FIG. 1 (a) shows a heat conductivity of 1 × 10 5.
Silicone gel with thermal conductivity of 1 × 10 ^{−3 to} 5 × 10 ⁻³ cal / cm · sec · ° C and a consistency of 10 to 80 on both sides of the support 1 of ^-4 cal / cm · sec · ° C or higher. The layer 2 is provided preferably with a thickness of 0.05 to 1.0 mm, and FIG. 1 (b) shows a separator on each surface of the silicone gel layer 2 of the heat conductive sheet shown in FIG. 1 (a). Plastic film 3 as
Are laminated. The consistency referred to here is the depth reached when a 1/4 cone is penetrated into a sample in an immiscible state at a temperature of 25 ° C for 5 seconds in accordance with JIS K 2220, and is 10 times the mm. It is a numerical value represented by the value of.

This heat-conducting sheet is formed, for example, by coating silicone gel on both sides of the support 1 to form a layer 2 thereof, and then laminating a plastic film 3 thereon, one side of the plastic film 3 being laminated. A method of applying an uncured silicone gel to prepare a laminate film having the layer 2 on the surface, and then laminating the silicone gel layer 2 on both sides of the support 1 with the laminate film, 1 and plastic film 3 are coated on one side with silicone gel, the layer 2 is laminated in the forward direction, and if necessary, the plastic film 3 is laminated on the silicone gel layer 2 exposed on the surface. Etc. can be obtained.

As described above, the support 1 used in the heat conductive sheet of the present invention has a thermal conductivity of 1 × 10 ^-4 cal / cm.
A substrate having a temperature of sec · ° C or higher is used, but the support 1 is preferably made of a rigid body or an elastic body. A material having a thermal conductivity of less than 1 × 10 ⁻³ cal / cm · sec · ° C. has a high thermal resistance, so the thickness is preferably 0.5 mm or less. As a material constituting such a support, aluminum,
Metal foil (sheet) of copper, iron, stainless steel, etc., thermal conductivity of 3 × 10 ^-4 to 8 × 10 ^-4 cal / cm ・ sec ・ ° C polyimide or polyester plastic sheet or film, thermal conductivity Of 4 × 10 ⁻⁴ to 8 × 10 ⁻⁴ cal / cm · sec · ° C. silicone rubber, polyurethane or other elastomeric sheet or film having a thermal conductivity of 2.5 × 10 ⁻⁴ , these same or different types of sheets or films And the like. Among these, copper is more likely to be oxidized than aluminum, and when drawn into a foil shape, wrinkles are likely to occur due to the effect of external stress, and this wrinkle has the disadvantage of reducing the thermal conductivity due to point contact. However, iron and stainless steel have poor workability such as cutting and cutting, and are inferior in terms of weight reduction.

As a suitable material which does not have such drawbacks and is economically effective, a heat conductive powder formed by mixing a heat conductive powder such as aluminum foil, alumina powder, and titanium oxide powder into silicone rubber has a thermal conductivity of 1 × 10 ^{-3 to} 5 × 10 ^-3 cal / c
There is a silicone rubber sheet with high thermal conductivity in the range of m / sec / ° C. The thickness of these supports is 0.0
25 ~ 0.10mm, 0.2 with high thermal conductive silicone rubber sheet
~ 1.0 mm is preferable, and generally, if the thickness exceeds 1.0 mm, it becomes difficult to cut, and if it is less than 0.01 mm, the handling property at the time of adhesive molding the silicone gel is deteriorated and wrinkle deformation easily occurs, so 0.01 ~ It is preferably 1.0 mm.

The silicone gel layer 2 covering both sides of the support 1 is inferior in thermal conductivity to the silicone gel alone, and therefore, for example, per 100 parts by weight of vinyl group-containing organopolysiloxane having a viscosity of 1 to 20 P, A metal powder such as an alumina powder or a titanium oxide powder or a thermally conductive powder such as a boron nitride powder is preferably blended at a ratio of 50 to 500 parts by weight. When a thermally conductive powder is blended with a vinyl group-containing organopolysiloxane having a viscosity of more than 20 P, the viscosity is increased and the fluidity is lowered, so that the workability in forming the silicone gel layer is lowered. Further, the compounding amount of the heat conductive powder to the vinyl group-containing organopolysiloxane is 50
If it is less than 1 part by weight, the thermal conductivity will be less than 1 × 10 ^-3 cal / cm · sec · ° C, and if it exceeds 500 parts by weight, the consistency will be less than 10, and the viscosity will increase and the fluidity will decrease, resulting in Workability in forming the layer is reduced.

As described above, the silicone gel layer 2 is formed by mixing the thermally conductive powder into the silicone gel alone, so that the thermal conductivity is 1 × 10 ^{−3 to} 5 × 10 ⁻³ cal / cm · sec · It can have a consistency of 10-80 at ° C. 1x thermal conductivity
10 ^-3 cal / cm · is less than sec · ° C. is not obtained efficient heat transfer, the incorporation of thermally conductive powder until more than ^{5 × 10 -3 cal / cm ·} sec · ℃, consistency of less than 10 It becomes a hard layer, the adhesion followability is poor with respect to the irregularities on the surface of the heat dissipation member, the contact heat resistance increases, and similarly, efficient heat conduction cannot be obtained. The consistency of the silicone gel layer cannot exceed 80 due to the mixing of the thermally conductive powder, and if it is less than 10, the unevenness on the top surface of the semiconductor element or the surface of the heat dissipation member cannot be absorbed, resulting in poor adhesion.

The thickness of the silicone gel layer is 0.05 to 1.0 m
m, especially about 0.25 mm is preferable (see FIG. 4 described later), and if it is less than 0.05 mm, it is difficult to absorb the unevenness of the top surface of the semiconductor element or the heat sink that is the heat dissipation member, so the adhesion tends to deteriorate, On the other hand, when it exceeds 1.0 mm, the heat resistance of the silicone gel layer becomes high, the balance between the adhesiveness and the heat resistance becomes poor, and the heat dissipation characteristics deteriorate. Since the silicone gel layer thus obtained has a unique adhesive property, it easily adheres to the top surface of the semiconductor element and the heat sink body. In the heat conductive sheet of the present invention, it is preferable to laminate a plastic film as a carrier or a dust protector on the surface of the silicone gel layer, and the silicone gel layer can be stored by winding this on a core material and storing it as a roll. It is possible to prevent the adhesion of dust and the like due to the adhesiveness, peel off the plastic film immediately before use, and cut out the required length for use.

FIG. 2 is a schematic explanatory view showing an example of a manufacturing process of the heat conductive sheet of the present invention. The support 11 (indicated by a solid line) made of a long aluminum foil is rewound from the winder 12, and the silane coupling agent 14 is sprayed onto the surface of the support 11 by the spraying device 13, and then introduced into the drying furnace 15 and dried. The uncured silicone gel 17 is applied to the same surface by the application device 16 to form a silicone gel layer. After introducing this into the curing device 18 and curing it, a plastic film 21 (from the winder 20) is laminated on the surface with a laminator 19,
The intermediate product 22 is wound on the winder 23. Obtained intermediate product
22 (hereinafter referred to as a chain line) is reversed and mounted on the winder 12, and the same work as above is repeated to laminate the plastic film 21. As a result, a heat conductive sheet similar to that shown in FIG. can get. This is slit into a predetermined width by a slitter 24, cut into a predetermined length by a cutter 25, and wound as a product 27 on a winder 26.

[0013]

EXAMPLES Hereinafter, specific embodiments of the present invention will be described with reference to examples. (Example 1) First, addition reaction type silicone gel KE-104G
100 parts by weight of EL (trade name, manufactured by Shin-Etsu Chemical Co., Ltd.) is mixed with 150 parts by weight of alumina powder, and the thermal conductivity is 2.5 × 10 ^-3 cal /
An uncured thermally conductive silicone gel having a cm · sec · ° C., a consistency of 30, and a viscosity of 200 P was prepared. On the other hand, thickness is 0.05m
m, size 300 mm × 300 mm, thermal conductivity 5.6 × 10 ^-1 cal / cm ・
A silane coupling agent KBM-403 (same as above) was applied to both surfaces of an aluminum foil at sec. ° C, and dried at 150 ° C for 3 minutes to prepare a product. On a polyester film as a carrier with a thickness of 0.05 mm, which was previously coated with a surfactant as a release agent and dried, the above uncured thermally conductive silicone gel was applied with a screen printer equipped with a ^# 100 mesh screen. , And was printed to form a layer with a thickness of 0.225 mm. This polyester film is attached to both sides of the aluminum foil with the printed side facing, 120 ° C
Heat treatment for 15 minutes to cure and form a thermally conductive silicone gel layer and adhere it to an aluminum foil.
Similar to the structure shown in (b), a structure in which a thermally conductive silicone gel layer is integrally formed on both sides of an aluminum foil (thickness 0.50 mm), and a polyester film is adhered on both sides of the structure. Thermal conductive sheet (total thickness is 0.60m
m).

This is cut or punched into a predetermined size, for example, 20 mm × 20 mm, leaving the polyester films on both sides, and a plurality of heat conductive sheets are arranged in a lattice on one polyester film. And The heat conductive sheet before cutting or punching is cut into a size of 50 mm × 50 mm, and its heat transfer performance is measured with the model heater test device (10 W) shown in FIG. 3 at each elapsed time (minutes, horizontal axis). When the temperature rise (° C., vertical axis) of the heater was examined, the results shown by the solid line in FIG. 4 were obtained. The dotted line in the figure shows the case of the conventional method, and the chain line shows the case of not using the heat dissipation member. 3 (a) is a schematic front view of the model heater test apparatus, and FIG. 3 (b) is a circle in FIG. 3 (a).
An enlarged front view of a portion, in which 31 is a heat sink, 32 is a heat conductive sheet, 33 is a heater, and 34 is a thermocouple for measuring the heater surface temperature.

Example 2 A thermal conductive sheet was prepared in the same manner as in Example 1 except that the thickness of the thermally conductive silicone gel was changed, and the same model heater test apparatus as in Example 1 was used. When the relationship between the thickness of the silicone gel layer and the temperature rise of the heater after 30 minutes was examined, the results shown in FIG. 5 were obtained.

(Example 3) In Example 1, the long aluminum foil 11 was replaced with a long one having a thickness of 0.20 mm, a width of 300 mm and a thermal conductivity of 2.0 × 10 ^-3 cal / cm · sec · ° C. Use a silicone rubber sheet and reduce the thickness of the thermally conductive silicone gel layer to 0.2.
In the same manner except that the length was set to 25 mm, a long heat-conducting sheet (total thickness of 0.75 mm) with a structure in which a heat-conducting silicone gel layer and a 0.05 mm-thick polyester film were laminated on both sides of a silicone rubber sheet. mm). 30mm for this
Cut into a size of × 30 mm, and its thermal conductivity was measured using a model heater test device (6 W) shown in FIG.
When the temperature rise (° C., vertical axis) of the heater was examined for each horizontal axis, the results shown by the dotted line in FIG. 6 were obtained. The solid line in the figure shows the case where the heat conductive sheet obtained in Example 1 is used.

7A and 7B are vertical sectional views showing examples of application of the heat conductive sheet 71 of the present invention. FIG. 7A shows an example of attachment to the IC package 73. It is transmitted to the heat sink body 72 via the sheet 71 and radiates heat upward. FIG. 7B shows an example of mounting on the printed circuit board 74, and the heat of the IC package 73 is radiated downward from the opening of the printed circuit board 74 via the heat conductive sheet 71. FIG.
(C) is an example of mounting to the IC package 73 of another mode, and the heat of a large number of IC packages 73 is radiated upward from the heat sink body 72 via the heat conductive sheet 71.

[0018]

EFFECTS OF THE INVENTION The heat conductive sheet of the present invention can absorb the irregularities on the surface of the heater and the heat radiating plate and reduce the contact heat resistance, and can obtain a good heat radiating effect. It is much easier to handle and easier to work than the method of applying grease. Since the contact surface is a silicone gel with adhesiveness,
There is no need to mechanically fix the heat sink body.

[Brief description of the drawings]

FIG. 1A and FIG. 1B are vertical cross-sectional front views illustrating different embodiments of the heat conductive sheet of the present invention.

FIG. 2 is a schematic explanatory view showing an example of a manufacturing process of the heat conductive sheet of the present invention.

FIG. 3 (a) is a schematic front view of a model heater test device for measuring heat conduction performance, and FIG. 3 (b) is an enlarged front view of a portion ◯ in FIG.

FIG. 4 is a graph showing the relationship between the temperature rise of the heater and the elapsed time (minutes) between the heat conductive sheet of the present invention (solid line) obtained in Example 1 and the case of the conventional method (dotted line and chain line). is there.

FIG. 5 is a graph showing the relationship between the thickness of the silicone gel layer and the temperature rise of the heater after 30 minutes for the heat conductive sheets produced in Example 2 with the thickness of the silicone gel layer changed.

FIG. 6 is a graph showing the relationship between the temperature rise of the heater and the elapsed time (minutes) for the heat conductive sheets of the present invention obtained in Example 1 (solid line) and Example 3 (dotted line).

7A and 7B are vertical cross-sectional views showing examples of application of the heat conductive sheet of the present invention. FIG. 7A shows an example of mounting on an IC package, FIG. 7B shows an example of mounting on a printed circuit board, and FIG. c) is an example of attachment to an IC package of another aspect.

[Explanation of symbols]

1 ... Support, 2 ... Silicone gel layer, 3 ... Plastic film, 11 ... Support, 12, 20, 23, 26 ... Winding machine, 13
... Spraying device, 14 ... Silane coupling agent, 15 ... Drying furnace, 16 ... Coating device, 17 ... Silicone gel, 18 ... Curing device, 19 ... Laminator, 21 ... Plastic film, 22 ...
Intermediate product, 24 ... Slitter, 25 ... Cutter, 27 ... Heat conduction sheet, 31 ... Heat radiation plate, 32 ... Heat conduction sheet, 33 ... Heater, 34 ...
Thermocouple, 71 ... Thermal conductive sheet, 72 ... Heat sink body, 73 ...
IC package, 74 ... Printed circuit board.

Claims (3)

[Claims] 1. A thermal conductivity of 1 × 10 ^{−3 to} 5 × 10 ⁻³ cal / c on both sides of a support having a thermal conductivity of 1 × 10 ⁻⁴ cal / cm · sec · ° C. or higher.
A heat conductive sheet comprising a silicone gel layer having a consistency of 10 to 80 at m · sec · ° C. 2. The heat conductive sheet according to claim 1, wherein the silicone gel layer has a thickness of 0.05 to 1.0 mm. 3. The heat conductive sheet according to claim 1, wherein a plastic film is laminated on the surface of the silicone gel layer.