Thermally Conductive Grease Preparation And
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POLYMER MATRIX COMPOSITE: THERMALLY CONDUCTIVE GREASE PREPARATION AND CHARACTERIZATION A Thesis Presented to The Graduate Faculty of the University of Akron In Partial Fulfillment of the Requirements for the Degree Master of Science Amit Adhikari August, 2019 POLYMER MATRIX COMPOSITE: THERMALLY CONDUCTIVE GREASE PREPARATION AND CHARACTERIZATION Amit Adhikari Thesis Approved: Accepted: 1 1 Advisor Department Chair Dr. Jiahua Zhu Dr. Michael Cheung 1 _________________________ Committee member Interim Dean of the college Dr. Rajeev Gupta Dr. Craig Menzemer 1 1 Committee member Dean of the Graduate School Dr. Zhenmeng Peng Dr. Chand Midha 1 04/30/2019 ii ABSTRACT The next generation electronic devices are expected to be small in size and of magnified capacity. Denser packaging of the active components is important to miniaturize the electronic devices. Denser packaging is feasible only when heat generated by heat sources is quickly and effectively carried away to the heat sink. Next generation electronic devices with high performance microprocessors and integrated circuits along with diminished volume have led to major heat dissipation issue. Heat dissipation helps to control the temperature of the electronic devices at a desired level. Heat is dissipated to the heat sink from heat generator by the process of thermal conduction. Due to irregularities on the surfaces of the heat generator and heat sink, air is entrapped, and the air gap is formed in the path of thermal conduction. Air gap disturbs the thermal conduction as air is a really poor thermal conductor with a thermal conductivity of 0.026 W/mK. at room temperature. Air acts as a thermal barrier preventing the effective heat transfer between the heat source and heat sink. Different kind of thermal interface materials are used to fill up the air gap between the heat generator and the heat sink to improve thermal conduction. Introduction of thermal interface material can significantly increase the performance of electronic device. In a typical power electronic package, a grease is used as thermal interface material. Thermal conductive paste with high thermal conductivity (much greater than air) fills up all the air gaps between the heat generator and the heat sink to improve iii the thermal conduction. Development of the thermal conductive paste with low thermal resistance, high thermal conductivity and low electric conductivity is challenging and the most important aspect in today’s electronic industries. In the current study, we have tried to overcome this challenge by developing a thermally conductive grease with low thermal resistance, high thermal conductivity and low electric conductivity. iv ACKNOWLEDGEMENTS I would like to express heartfelt gratitude to my advisor Dr. Jiahua Zhu, for being immeasurably supportive during the past two years for the timely completion of my Master’s degree. His constant encouragement towards completing this thesis and furthering my education has played a vital role in both my academic and professional career. This thesis is a result of his constant motivation and guidance. Moreover, I would like to thank my committee members: Dr. Rajeev Gupta and Dr. Zhenmeng Peng for their valuable advice and suggestions. Their time, instructions and ideas were immensely helpful in the betterment of the project since its inception. Furthermore, I would like to acknowledge all my labmates: Dr. Liwen Mu, Tuo Ji, Nitin Mehra, Yifan Li, Han Lin, Logan Brisbin for their support, constructive feedbacks and company. The time spent on the lab were some of the fun and rewarding experiences that will always remain close to my heart. Most importantly, I would like to express my deepest appreciation to my family for being enormously encouraging and helpful. Thank you very much for always being my strength. You all are the reason I am here today and everywhere I will be tomorrow. Finally, I appreciate the Department of Chemical and Bio-molecular Engineering for providing me the platform to further my education and for the successful completion of my Master’s degree. v TABLE OF CONTENTS Page LIST OF TABLES ............................................................................................................. ix LIST OF FIGURES ............................................................................................................ x CHAPTER I. INTRODUCTION ....................................................................................................... 1 Motivation ...................................................................................................................... 1 Introduction .................................................................................................................... 1 Outline ............................................................................................................................ 4 Literature Review ........................................................................................................... 4 Overview ................................................................................................................. 4 Thermal Conductivity ........................................................................................ 6 Thermal Resistance ............................................................................................ 6 Electric conductivity .......................................................................................... 7 Viscosity ............................................................................................................. 7 Stability .............................................................................................................. 7 Outgassing .......................................................................................................... 8 Cost .................................................................................................................... 8 Theoretical Background .......................................................................................... 8 Base Materials:...................................................................................................... 10 Silicone Oil ...................................................................................................... 10 Epoxy Resin ..................................................................................................... 11 Polybenzoxazine .............................................................................................. 12 Poly (alpha-olefin) oil ...................................................................................... 12 vi Fillers .................................................................................................................... 12 Metallic Fillers ................................................................................................. 13 Ceramic Fillers ................................................................................................. 14 Carbon-based Fillers ........................................................................................ 14 Hybrid Fillers ................................................................................................... 14 Surface Modification of Fillers ............................................................................. 15 Commercial Greases ............................................................................................. 15 Conclusion ................................................................................................................... 18 II. THERMALLY CONDUCTIVE GREASE WITH BN ............................................... 19 Introduction .................................................................................................................. 19 Experimental ................................................................................................................ 20 Materials ............................................................................................................... 20 Fillers’ Properties .................................................................................................. 20 Preparation of Thermal Paste ................................................................................ 21 Characterization .................................................................................................... 22 2.3 Results and Discussion ........................................................................................... 24 Introduction .................................................................................................................. 37 Experimental ................................................................................................................ 37 Materials ............................................................................................................... 37 Fillers’ Properties .................................................................................................. 38 Preparation of Thermal Paste ................................................................................ 39 Characterization .................................................................................................... 41 Results and Discussion ................................................................................................. 42 III. CONCLUSION AND FUTURE WORKS ................................................................. 50 Conclusion ..................................................................................................................