用於快速，可靠和小型計算設備的現代技術的進步已導致每單位面積的高功率密度的發展。大部分熱量將使用各種散熱器消散。這些表面的不平整或粗糙提供了對從熱源到散熱器的熱流的阻力。由於表面粗糙度（稱為熱接觸電阻（TCR））導致的接觸電阻必須最小化，以便從熱源到散熱器的有效熱傳遞。在接觸表面之間使用熱界面材料（TIM）是降低熱接觸電阻的有效方法。表面粗糙度的降低顯著降低了接觸電阻。此外，研究了壓力和表面溫度對TCR的影響。它清楚地表明壓力和溫度的增加降低了TCR。減量取決於使用的​​TIM。熱循環負載的TCR變化也取決於Tim使用的。類似地，如果TIM在最大功率下熔化，則對電源變化的研究對TCR有影響。已經嘗試解決當使用熔化的TIM時滲出的問題。

Advancement of the modern generation for fast, reliable and small computing devices has led to development of high power density per unit area. Most of this heat is to be dissipated using the various heat sinks. The unevenness or roughness of these surfaces offer the resistance to the flow of heat from the heat source to heat sink. This resistance on the contact due the roughness of the surface known as Thermal Contact Resistance (TCR) has to be minimized for effective heat transfer from heat source to heat sink. Using Thermal Interface Material (TIM) between the contact surfaces has been the effective way to reduce the thermal contact resistance. Decrease of surface roughness significantly reduces the contact resistance. Moreover, study on effect of pressure and surface temperature on TCR was performed. It clearly indicates increase of pressure and temperature decreases TCR. The decrement depends on the TIM used. TCR variation on Thermal cycling loading also depends on the Tim used. Similarly study of variation of power supply has effect on the TCR if the TIM melts on the maximum power. An attempt has been made to address the problem of oozing out when TIM that melts is used.

ABSTRACT i
ACKNOWLEDGEMENT iii
LIST OF FIGURES vi
LIST OF TABLES viii
NOMENCLATURE viii
Chapter 1 Introduction 1
1.1 Background 1
1.2 Thermal contact resistance 1
1.3 Thermal interface materials 3
1.3.1 Thermal Grease 4
1.3.2 Phase Change materials 5
1.3.3 Thermally Conductive Elastomers (Gels) 6
1.3.4 Carbon Based TIMs 6
1.4 Objectives of present study 7
Chapter 2 Literature Review 8
2.1 Solid-Solid Interface Thermal Contact Resistance Modelling 12
2.1.1 Plastic Contact Conductance Model 14
2.1.2 Elastic Contact Conductance Model 15
2.1.3 Bulk Resistance Method 16
2.2 Solid Liquid Interaction Contact Resistance Model 18
Chapter 3 Experimental Apparatus And Procedures 22
3.1 Experimental Method 22
3.2 Test Piece 23
3.3 Thermal Interface Materials 29
3.4 Experimental Schematic and Setup assembly 30
3.4.1 DC Power Supply 33
3.4.2 Water Bath 34
3.4.3 Data Acquisition System 35
3.4.3 Load cell 36
3.5 Experimental Procedure 36
3.6 Data Reduction 37
Chapter 4 Results and Discussions 39
4.1 Effect of Pressure on Thermal Contact Resistance 39
4.2 Effect of Brinell hardness of TIM on Thermal Contact Resistance 44
4.3 Effect of temperature on thermal contact resistance 45
4.4 Effect of roughness on contact resistance 46
4.5 Effect of Thermal cycle loading 48
4.6 Effect of Pattern of Power Supply 52
Chapter 5 Conclusions and Future Works 55
5.1 Conclusions 55
5.2 Future Works 56
Reference 57
Appendix A 61
Appendix B 62

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