Development of a Oxygen Sensor for Marine ... - DTU Nanotech

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48 CHAPTER 5. FABRICATION 5.3 Summary The fabrication steps have been outlined and explained, and while there are always the possibility of changes or variations in parameters in each step, the process as described in this chapter, should be duplicable by others.
Chapter 6 Problems and Solutions In almost every project some unexpected problems appears, ranging from merely inconvenient problems such as cleanroom machinery being out of work, to more actual problems, such as fabrications steps being more complicated than they appear on paper. In this chapter some of the problems encountered during the process of creating the Clark sensor will be highlighted, as well as how they were solved when possible. 6.1 Wirebonding As mentioned in Chapter 5, the first, and at the time the only, choice for connecting the chip to the flex print was wirebonding. Wirebonding is basically done by having a needle, with a metal (Al) thread through it, pressing down on the contact pad of the chip, and then through the use of ultrasound and vibrations attach the thread. The similar process is then repeated on the flex print, at which time the rest of the thread is snapped off. However this would soon prove to be a lot more complicated than it sounds. For some unexplainable reasons the thread refused to perform the second attachment, whether it was on the gold on the chip, or on the flex print. Albeit some were wirebondings were successful, they were few and there was far between them. Why this is so, remained a mystery for a while, however there was some problems with the machine at the time. However a later examination of the flex print revealed that the metal on it was tin covered copper. Therefor it was impossible to bond to the flex print, unless the tin was scraped off, as 49
Page 1 and 2:
Development of a Oxygen Sensor for
Page 3:
Abstract This thesis described the
Page 7 and 8: Contents 1 Introduction 1 1.1 Disso
Page 9 and 10: CONTENTS vii B Fabrication Process
Page 11 and 12: Chapter 1 Introduction Roughly 70 %
Page 13 and 14: 1.1. DISSOLVED OXYGEN LEVEL 3 K = a
Page 15 and 16: 1.2. THESIS OUTLINE 5 In Chapter 8
Page 17 and 18: Chapter 2 Optodes and ISFET There a
Page 19 and 20: 2.2. ISFET (ION SELECTIVE FIELD EFF
Page 21 and 22: 2.3. SUMMARY 11 of oxygen molecules
Page 23 and 24: Chapter 3 Theory of the Clark Senso
Page 25 and 26: 3.1. CHEMISTRY OF THE CLARK SENSOR
Page 33 and 34: 3.2. THE POTENTIOSTAT 23 Reference
Page 35 and 36: 3.2. THE POTENTIOSTAT 25 Working El
Page 37 and 38: Chapter 4 System Design The sensor
Page 39 and 40: 4.2. ACTUAL DESIGN 29 seen on figur
Page 41 and 42: 4.2. ACTUAL DESIGN 31 The third des
Page 43 and 44: 4.3. TEMPERATURE SENSOR 33 Figure 4
Page 45 and 46: 4.3. TEMPERATURE SENSOR 35 a Pt300,
Page 47 and 48: 4.4. PACKAGING 37 Figure 4.11: Clos
Page 49 and 50: 4.4. PACKAGING 39 90 mm 15 mm 6 mm
Page 51 and 52: Chapter 5 Fabrication The fabricati
Page 53 and 54: 5.1. PROCESSING 43 Figure 5.4: Alig
Page 55 and 56: 5.2. BACK-END PROCESSING 45 under e
Page 57: 5.2. BACK-END PROCESSING 47 5.2.2 A
Page 61 and 62: 6.1. WIREBONDING 51 make a line bet
Page 63 and 64: 6.2. THE FLEX PRINT 53 The reason b
Page 65 and 66: 6.3. THE ’O’-RING 55 Figure 6.8
Page 67 and 68: Chapter 7 Evaluation of Results and
Page 69 and 70: 7.2. TEMPERATURE SENSOR 59 Figure 7
Page 71 and 72: 7.4. SUMMARY 61 Figure 7.5: Polarog
Page 73 and 74: Chapter 8 Conclusion The primary go
Page 75 and 76: Bibliography [1] http://earthobserv
Page 77 and 78: BIBLIOGRAPHY 67 [26] W.E. Morf. The
Page 79 and 80: Appendix A Silicide Recipe The foll
Page 81 and 82: Appendix B Fabrication Process 71
Page 84 and 85: 74 APPENDIX B. FABRICATION PROCESS
Page 86: 76 APPENDIX C. PROCESS SEQUENCE
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