Thermal Interface Material And Semiconductor Device Incorporating The Same

Abstract

A semiconductor device includes a heat source, a heat-dissipating component for dissipating heat generated by the heat source, and thermal interface material filled in a space formed between the heat source and the heat-dissipating component. The thermal interface material includes 50% to 90% in weight of at least one metal powders having an average particle size of 2 to 20 .mu.m and selected from the group consisting of spherical tin powders and powders of memory alloy, and 5% to 15% in weight of silicone oil having a viscosity from 50 tO 50,000 cs at 25.degree. C.

Description

1. FIELD OF THE INVENTION

[0001] The present invention relates to a thermal interface material which is interposable between a heat-generating electronic component and a heat dissipating component; the present invention also relates to a semiconductor device using such a thermal interface material.

2. DESCRIPTION OF RELATED ART

[0002] With the fast development of the electronic industry, advanced electronic components such as CPUs (central processing units) are being made to have ever quicker operating speeds. During operation of the advanced electronic components, a larger amount of heat is generated. In order to ensure good performance and reliability of the electronic components, the operational temperature of the electronic components must be kept within a predetermined range. Generally, a heat dissipating apparatus such as a heat sink or a heat spreader is attached to a surface of the electronic component, so that the generated heat is dissipated from the electronic component to ambient air via the heat dissipating apparatus. However, the contact surfaces between the heat dissipating apparatus and the electronic component are rough and therefore are separated from each other by a layer of interstitial air, no mater how precisely the heat dissipating apparatus and the electronic component are brought into contact; thus, the interface thermal resistance is relatively high. A thermal interface material is preferred for being applied to the contact surfaces to eliminate the air interstices between the heat dissipating apparatus and the electronic component in order to improve heat dissipation.

[0003] The thermal interface material includes base oil and fillers filled in the base oil. Thereinto, the base oil is used for filling the air interstices to achieve an intimate contact between the heat dissipating apparatus and the electronic component, whilst the fillers are used for improve the heat conductivity of the thermal interface material to thereby increase the heat dissipation efficiency of the heat dissipating apparatus. Therefore, the fillers having high heat conductivities are the preferred choice in improving the heat conductivity of the thermal interface material.

SUMMARY OF THE INVENTION

[0004] The present invention relates to a thermal interface material for electronic products and a semiconductor device using the thermal interface material. According to a preferred embodiment of the present invention, the semiconductor device includes a heat-generating electronic component, a heat-dissipating component for dissipating heat generated by the electronic component, and a thermal interface material filled in a space formed between the electronic component and the heat-dissipating component. The thermal interface material includes 50% to 90% in weight of metal powders having an average particle size of 2 to 20 .mu.m and selected from the group consisting of spherical tin powders and powders of memory alloy, and 5% to 15% in weight of silicone oil having a viscosity from 50 tO 50,000 cs at 25.degree. C.

[0005] Other advantages and novel features of the present invention will become more apparent from the following detailed description of preferred embodiment when taken in conjunction with the accompanying drawings, in which:

BRIEF DESCRIPTION OF THE DRAWINGS

[0006] Many aspects of the present thermal interface material can be better understood with reference to the following drawings. The components in the drawings are not necessarily drawn to scale, the emphasis instead being placed upon clearly illustrating the principles of the present thermal interface material. Moreover, in the drawings, like reference numerals designate corresponding parts throughout the several views.

[0007] FIG. 1 is an assembled view of a semiconductor device according to a preferred embodiment of the present invention;

[0008] FIG. 2 is an explanatory view of a thermal interface material of the present invention, showing a normal state of the thermal interface material; and

[0009] FIG. 3 is an explanatory view of the thermal interface material of FIG. 2, showing an operation state of the thermal interface material when it is disposed between an electronic component and a heat-dissipating component and is urged by the heat-dissipating component towards the electronic component under a pressure.

DETAILED DESCRIPTION OF THE INVENTION

[0010] Referring to FIG. 1, an electronic device 10 includes an electronic component 12, such as a central processing unit (CPU) of a computer disposed on a circuit board 11, wherein the electronic component 12 is a heat source of the electronic device 10. The electronic device 10 further includes a heat-dissipating component 13 for dissipating heat generated by the electronic component 12, and a thermal interface material 14 filled in a space formed between the electronic component 12 and the heat-dissipating component 13. The electronic component 12 needs to be cooled. The heat-dissipating component 13 is a heat sink, which includes a base 131 and a plurality of fins 133 disposed on the base 131. The heat-dissipating component 13 is attached to the circuit board 11 via a resilient fixing member 15, which can be deformed to provide a resilient force in clamping the heat-dissipating component 13 onto the electronic component 12. The fixing member 15 clamps the base 131 of the heat-dissipating component 13 and the circuit board 11 together, thereby urging the base 131 downwardly towards the electronic component 12 via the resilient force exerted by the fixing member 15. The thermal interface material 14 is pressed by the heat-dissipating component 13, thus filling entirely the space formed between the electronic component 12 and a bottom face of the base 131 of the heat-dissipating component 13.

[0011] The thermal interface material 14 is a silicone grease composition having high thermal conductivity, and includes a base oil 141 and an amount of fillers 143 filled in the base oil 141.

[0012] The base oil 141 is 5% to 15% in weight of the thermal interface material 14; that is, the base oil 141 has a weight which is no less than 5% and no more than 15% of a weight of the thermal interface material 14. The base oil 141 is silicon oil which has a viscosity in the range of 50 to 50,000 cs at 25.degree. C. The major component of the silicon oil is organopolysiloxanes, whose formula is RaSiO(4-a)/2. Alternatively, the silicon oil may be organopolysilalkylenes, organopolysilanes, or copolymers. In the formula, R presents hydrocarbon group, which polymerizes with siloxanes to acquire corresponding organopolysiloxane, such as dimethylpolysiloxane, diethylpolysiloxane, methylphenylpolysiloxane, dimethylsiloxane-diphenylsiloxane copolymers or alkyl-modified methylpolysiloxane. In this embodiment, the organopolysiloxane is dimethylpolysiloxane, which is the major component of the dimethyl silicone oil. Alternatively, the R may present amino group, polyether group or epoxy group in the formula.

[0013] The fillers 143 are 50% to 90% in weight of the thermal interface material 14; that is, the fillers 143 have a weight which is no less than 50% and no more than 90% of the weight of the thermal interface material 14. The fillers 143 are selected from the group consisting of spherical tin powders and powders of memory alloy, such as Ni--nickel-titanium) alloy or Co--Zn--Al (cobalt-zinc-aluminum) alloy, which are easily to change their shape into a specific shape under a pressure or a raised temperature. Alternatively, the powders of the memory alloy may be a mixture of the Ni--Ti powders and the Co--Zn--Al powders. An average particle size of the fillers 143 is in the range of 2 to 20 um. When the fillers 143 are the mixture of the spherical tin powders and the powders of memory alloy, the ratio of the spherical tin powders to the powders of memory powder is in a range of 1:1 to 1:10 in weight.

[0014] The thermal interface material 14 further includes no more than 35% in weight of oxide powders (not shown) having an average particle size of 0.1 to 5 um and selected from the group consisting of zinc oxide and alumina powders. Alternatively, there may be no oxide powder filled in the base oil 141.

[0015] Particularly referring to FIG. 2, the fillers 143 of the thermal interface material 14 are substantially sphere-shaped in a normal state. In this state, the fillers 143 of the thermal interface material 14 are evenly distributed in the base oil 141 and space a distance from each other. The fillers 143 of the thermal interface material 14 do not have intimate contacts with each other. Referring to FIG. 3, when the heat-dissipating component 13 is disposed on the electronic component 12, the round-shaped fillers 143 of the thermal interface material 14 filled in the space between the electronic component 12 and the heat-dissipating component 13 are under pressure, whereby they change their shape to be ellipse-shaped fillers 143a. The ellipse-shaped fillers 143a of the thermal interface material 14 intimately contact with each other with increased area. Therefore, the thermal conductivity of the thermal interface material 14 is increased, and the heat generated by electronic component 12 can be easily transmitted to the heat-dissipating component 13 to be dissipated via the thermal interface material 14. Hereinafter, experimental data is provided to validate such a result.

[0016] Table 1 below shows heat resistances of thermal interface materials with different fillers. The weights of these thermal interface materials are the same, i.e., 50 g, and the base oils of these thermal interface materials are dimethyl silicone oils having a viscosity of 10,000 cs at 25.degree. C. The table 1 shows that the heat resistance of the present thermal interface material is lower than those of conventional thermal interface materials I and II. TABLE-US-00001 TABLE 1 Heat resistance Thermal interface Volume (.degree. C. material Fillers % cm.sup.2/w) The present thermal Spherical tin powder 50 0.343 interface material having an average vol % particle size of 5.0 .mu.m Conventional thermal Alumina (Al.sub.2O.sub.3) powder 50 0.618 interface material having an average vol % (I) particle size of 5.0 .mu.m Conventional thermal Zinc Oxide (ZnO) powder 30 0.860 interface material having an average vol % (II) particle size of 0.4 .mu.m

[0017] It is to be understood, however, that even though numerous characteristics and advantages of the present invention have been set forth in the foregoing description, together with details of the structure and function of the invention, the disclosure is illustrative only, and changes may be made in detail, especially in matters of shape, size, and indicated by the broad general meaning of the terms in which the appended claims are expressed.

Claims

1. A thermal interface material comprising: 5% to 15% in weight of base oil; and 50% to 90% in weight of fillers filled in the base oil, wherein the fillers have an average particle size of 2 to 20 .mu.m and are selected from the group consisting of spherical tin powders and powders made of memory alloys.

2. The thermal interface material as described in claim 1, wherein the base oil has a viscosity from 50 to 50,000 cs at 25.degree. C.

3. The thermal interface material as described in claim 1, wherein the base oil is silicone oil.

4. The thermal interface material as described in claim 3, wherein a major component of the silicone oil is organopolysiloxane.

5. The thermal interface material as described in claim 4, wherein the organopolysiloxane is dimethylpolysiloxane.

6. The thermal interface material as described in claim 1, wherein the ratio of the spherical tin powders to the powders of memory alloy is in a range of 1:1 to 1:10 in weight.

7. The thermal interface material as described in claim 1, wherein the memory alloy is Ni--Ti alloy.

8. The thermal interface material as described in claim 1, wherein the memory alloy is Co--Zn13 Al alloy.

9. The thermal interface material as described in claim 1, further comprising 0% to 35% in weight of oxide powders.

10. The thermal interface material as described in claim 9, wherein an average particle size of the oxide powders is in the range of 0.1 to 5 .mu.m.

11. The thermal interface material as described in claim 9, wherein the oxide powders are selected from the group consisting of zinc oxide and alumina powders.

12. A semiconductor device comprising: a heat source; a heat-dissipating component for dissipating heat generated by the heat source; and a thermal interface material filled in a space formed between the heat source and the heat-dissipating component, the thermal interface material comprising: 50% to 90% in weight of at least one metal powders having an average particle size of 2 to 20 .mu.m and selected from the group consisting of spherical tin powders and powders made of memory alloy; 5% to 15% in weight of silicone oil having a viscosity from 50 to 50,000 cs at 25.degree. C.; and 0% to 35% in weight of at least one oxide powders having an average particle size of 0.1 to 5 .mu.m and selected from the group consisting of zinc oxide and alumina powders.

13. The semiconductor device as described in claim 12, wherein the memory alloy is one of Ni--Ti alloy and Co--Zn--Al alloy.

14. The semiconductor device as described in claim 12, wherein a major component of the silicone oil is organopolysiloxane.

15. The semiconductor device as described in claim 14, wherein the organopolysiloxane is dimethylpolysiloxane.

16. The semiconductor device as described in claim 12, wherein a ratio of the spherical tin powders to the powders of memory alloy is in a range of 1:1 to 1:10 in weight.

17. A thermal interface material adapted for being applied between a heat-generating electronic component and a heat-dissipating component, comprising: a base oil; and fillers filled in the base oil, wherein the fillers comprise at least one of tin powders and powders of memory alloy.

18. The thermal interface material as described in claim 17, wherein the tin powders and the powders of memory alloy each have a spherical shape before the thermal interface material is applied between the heat-generating electronic component and the heat-dissipating component.

19. The thermal interface material as described in claim 18, wherein the tin powders and powders of memory alloy each have an elliptical shape after the thermal interface material is applied between the heat-generating electronic component and the heat-dissipating component.

20. The thermal interface material as described in claim 19, wherein the fillers further comprise oxide powders.