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Fabrication, Bonding, Assembly, and Testing of Metal-Based Louisiana State University LSU Digital Commons LSU Doctoral Dissertations Graduate School 2009 Fabrication, bonding, assembly, and testing of metal-based microchannel devices Fanghua Mei Louisiana State University and Agricultural and Mechanical College, [email protected] Follow this and additional works at: https://digitalcommons.lsu.edu/gradschool_dissertations Part of the Mechanical Engineering Commons Recommended Citation Mei, Fanghua, "Fabrication, bonding, assembly, and testing of metal-based microchannel devices" (2009). LSU Doctoral Dissertations. 1905. https://digitalcommons.lsu.edu/gradschool_dissertations/1905 This Dissertation is brought to you for free and open access by the Graduate School at LSU Digital Commons. It has been accepted for inclusion in LSU Doctoral Dissertations by an authorized graduate school editor of LSU Digital Commons. For more information, please [email protected]. FABRICATION, BONDING, ASSEMBLY, AND TESTING OF METAL-BASED MICROCHANNEL DEVICES A Dissertation Submitted to the Graduate Faculty of the Louisiana State University and Agricultural and Mechanical College in partial fulfillment of the requirement for the degree of Doctor of Philosophy in The Department of Mechanical Engineering By Fanghua Mei B.S., Shanghai Jiao Tong University, Shanghai, China, 2002 M.S., Shanghai Jiao Tong University, Shanghai, China, 2005 August, 2009 To my family ii ACKNOWLEDGEMENTS In the journey of my dissertation research, I would like to express my most sincere gratitude to my major professor, Dr. Wen Jin Meng, for his dedication and support throughout my research. The valuable research experience gained during these four years would not have been possible without his encouragement and support. I feel so honored to have Dr. Dorel Moldovan, Dr. Shengmin Guo, Dr. Sunggook Park, Dr. Pratul K. Ajmera, and Dr. Hak-Chul Shin to be my dissertation committee members. I thank you all for your continued support and guidance. I appreciate your positive comments and personal encouragement. I would like to thank Dr. Srinath Ekkad, Dr. Dean Miller, Mr. Jon Hiller, Dr. Dongmei Cao, Dr. Varshni Singh, and Dr. Jing Jiang for their collaboration and technical assistances. I also want to thank my lab mates, Bin Lu, Ke Chen, Yang Mu, Pritish Parida, and Wynn Phillips for their valuable suggestions and help. Very special thanks go to my dear wife, Yun Hu, for her understanding and strong support during these years. I would also like to thank my parents and sister who always understand me and encourage me in pursuing my goal. I also gratefully acknowledges partial project support from Louisiana Board of Regent through contracts LEQSF(2001-04)-RD-A-07, LEQSF(2004-07)-RD-B-06, and the National Science Foundation through grants DMI-0124441 (2001-05), CMMI-0400061 (2004-08), and CMMI-0556100 (2006-09). iii TABLE OF CONTENTS DEDICATION ………………………………………………………………..………… ii ACKNOWLEDGMENTS .……….…………….……………………………..………… iii ABSTRACT …………………………………………………………………..………… vii CHAPTER 1. INTRODUCTION OF CURRENT MICROFABRICATION TECHNOLOGIES FOR METAL-BASED MICROSTRUCTURES AND DEVICES ………………………………………………………………. 1 1.1 Introduction …………………………………………………………………. 1 1.2 Techniques for Fabricating Metal-Based HARMS …………………………. 1 1.2.1 Micromilling ………………………………………………………….. 2 1.2.2 Laser Micromachining ………………………………………………… 3 1.2.3 Micro Electrical Discharge Machining (µEDM) ……………………… 3 1.2.4 The LiGA Microfabrication Protocol …………………………………. 4 1.3 Replication of Metallic HARMS by Microscale Compression Molding …… 6 1.3.1 Surface Engineering of Mold Insert …………………………………... 6 1.3.2 Mechanical Properties of Mold Insert ………………………………… 8 1.4 Bonding of Metal-Based HARMS ………………………………………….. 11 1.5 Testing of Metal-Based Microchannel Heat Exchangers ...…………………. 12 1.6 Summary ……………………………………………………………………. 13 1.7 References …………………………………………………………………… 13 CHAPTER 2. EUTECTIC BONDING OF Al-BASED HIGH ASPECT RATIO MICROSCALE STRUCTURES USING Al-Ge NANOCOMPOSITE THIN FILM INTERMEDIATE LAYERS …………………………………….. 21 2.1 Introduction …………………………………………………………………. 21 2.2 Experimental Procedures …………………………………………………… 22 2.3 Results and Discussion ……………………………………………………… 24 2.4 Conclusion …………………………………………………………………... 30 2.5 References …………………………………………………………………… 30 CHAPTER 3. EVALUATION OF EUTECTIC BOND STRENGTH AND ASSEMBLY OF Al-BASED MICROFLUIDIC STRUCTURES ……………………. 33 3.1 Introduction …………………………………………………………………. 33 3.2 Experimental Procedures …………………………………………………… 34 3.3 Results and Discussion ……………………………………………………… 36 3.4 Conclusion …………………………………………………………………... 42 3.5 References …………………………………………………………………… 43 CHAPTER 4. STRUCTURE OF VAPOR-PHASE DEPOSITED Al-Ge THIN FILMS AND MECHANISM OF Al-Ge INTERMEDIATE LAYER BONDING OF Al-BASED MICROCHANNEL STRUCTURES …..………………….. 45 4.1 Introduction …………………………………………………………………. 45 iv 4.2 Experimental Procedures …………………………………………………… 46 4.2.1 Vapor-Phase Deposition of Al-Ge Thin Films ……...………………… 46 4.2.2 Compositional and Structural Characterization of Vapor-Phase Deposited Al-Ge Thin Films ……………………………………………………… 47 4.2.3 Bonding of Al-based Microscale Structures …………………………… 48 4.2.4 FIB Characterization of Bonded Al MHE Structures …………………. 50 4.3 Results and Discussion ……………………………………………………… 50 4.4 Conclusion ………………………………………………………………….. 59 4.5 References ………………………………………………………………….. 59 CHAPTER 5. EVALUATION OF BOND QUALITY AND ASSEMBLY OF Cu-BASED MICROFLUIDIC STRUCTURES WITH Al THIN FOIL INTERMEDIATE LAYERS ……………………….…………………... 62 5.1 Introduction …………………………………………………………………. 62 5.2 Experimental Procedures …………………………………………………… 63 5.2.1 Molding Replication of Cu-Based Microchannels …………………… 63 5.2.2 Bonding of Cu specimens with Al Thin Foil Intermediate Layers …… 63 5.2.3 Evaluation of Bond Quality …………………………………………… 64 5.2.4 Assembly of Cu-Based Microchannel Devices and MHE Prototypes … 64 5.2.5 Thermal Testing of Cu-Based MHE Prototypes ……………………… 65 5.3 Results and Discussion ……………………………………………………… 65 5.4 Conclusion ………………………………………………………………….. 72 5.5 References ………………………………………………………………….. 72 CHAPTER 6. BONDING OF Cu-BASED HIGH ASPECT RATIO MICROSCALE STRUCTURES WITH Sn INTERMEDIATE LAYERS ………………. 74 6.1 Introduction …………………………………………………………………. 74 6.2 Experimental Procedures …………………………………………………… 75 6.2.1 Bonding of Cu Specimens with Sn Thin Foil Intermediate Layers …… 75 6.2.2 Evaluation of Bond Quality …………………………………………..… 75 6.2.3 Bonding of Cu-based Microchannel Device Using Sn Thin Foil Intermediate Layer ...……………..…………………………………… 76 6.3 Results and Discussion ……………………………………………………… 76 6.4 Conclusion ………………………………………………………………….. 82 6.5 References ………………………………………………………………….. 82 CHAPTER 7. FABRICATION, BONDING, ASSEMBLY, AND HEAT TRANSFER TESTING OF Al- AND Cu- BASED MICROCHANNEL DEVICES … 85 7.1 Introduction …………………………………………………………………. 85 7.2 Fabrication and Assembly ………………………………………………….. 86 7.2.1 Insert Fabrication ……………………………………………………... 86 7.2.2 Molding Replication ………………………………………………….. 87 7.2.3 Assembly and Bonding ……………………………………………….. 88 7.2.4 Measurement of MHE Geometry …………………………………….. 91 7.3 Flow and Heat Transfer Testing ……………………………………………. 92 7.3.1 Experimental Setup …………………………………………………… 92 v 7.3.2 Measurements ………………………………………………………… 95 7.3.3 Data Reduction ……………………………………………………….. 96 7.3.4 Results and Discussion ………………………………………………. 97 7.4 Conclusion …………………………………………………………………. 103 7.5 Nomenclature ………………………………………………………………. 103 7.6 References …………………………………………………………………... 104 CHAPTER 8. FURTHER ANALYSIS OF FLOW AND HEAT TRANSFER CHARACTERISTICS IN Cu-BASED MICROCHANNEL DEVICES ... 108 8.1 Introduction …………………………………………………………………. 108 8.2 Experimental Procedures …………………………………………………….. 108 8.2.1 Molding Replication of Cu-Based Microchannels …………………….. 108 8.2.2 Bonding and Assembly of Cu-Based MHEs …………………………. 109 8.3 Fluid Flow and Heat Transfer Measurements ………………………………. 112 8.3.1 Experimental Setup …………………………………………………… 112 8.3.2 Measurements ………………………………………………………… 114 8.4 Results and Discussion …………………..…………………………………. 116 8.4.1 Data Reduction ………………………………………………………… 116 8.4.1.1 Flow Characteristics and Friction Factor ………..……………. 116 8.4.1.2 Heat Transfer Characteristics and Nusselt Number……..…….. 116 8.4.2 Data Analysis and Discussion ………………….……………………... 117 8.4.2.1 Flow Characteristics and Friction Factor ………………..……. 117 8.4.2.2 Heat Transfer Characteristics and Nusselt Number……..…….. 119 8.5 Conclusion …………………………………………………………………. 122 8.6 Nomenclature ………………………………………………………………. 123 8.7 References …………………………………………………………………... 124 CHAPTER 9. CONCLUSION………………………………………………………… 126 APPENDIX. LETTERS OF COPYRIGHT PERMISSION……………...………..…. 128 VITA ……………………………………………………………………………………. 135 vi ABSTRACT Microsystem technologies are believed to be an important part of the contemporary technological foundation and are becoming a commercially significant specialty area in manufacturing. The design and fabrication of microscale engineering structures has the potential of generating revolutionary changes in many products over a wide range of industrial sectors. Metal-based microchannel heat exchangers (MHEs) promise high heat transfer coefficients together with mechanical robustness, and are of interest for a wide range of applications. Fabrication technologies capable of creating high-aspect-ratio microscale structures (HARMSs) in metals such as Cu at low cost and high throughput are of particular interest. Likewise, simple and reliable bonding and assembly techniques are critical for building functional metal-based microfluidic devices. This dissertation focuses on various
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