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PAGE 14 14 Abstract of Dissertation Presented to the Graduate School of the University of Florida in Partial Fulfillment of the Requirements for the Degree of Doctor of Philosophy BIMODAL MOLECULAR WEIGHT POLYVINYL PYRROLIDONE-SYNTHESIZED SILVER NANOPARTICLES FOR USE AS LOW-CURING TEMPERATURE CONDUCTIVE MATERIALS By Glen Patrick Flores August 2009 Chair: Christopher D. Batich Major: Materials Science and Engineering In the past quarter century, many researchers have begun materials investigations into lowcuring temperature metallizations. These low-temperature metallizations may allow for the design of complex electronic circuits on low-melting temperature substrates. Metal nanoparticles are of great interest due to their ability to begi n sintering at temperatures as low as 150C. The small size and environmental stability of gold and silver nanoparticles allows them to be economically and rapidly printed from industrial and commercial printing equipment. Upon heat treatment above their sintering temperature, these printed nanoparticles form continuous metallic lines. Gold and silver conductive line widths as small as a few micrometers have been made using nanoparticles in inkjet and pad prin ting techniques. Such techniques may also help decrease the high manufacturing costs associated with other metallization techniques such as photolithography. Electronic devices that utilize low-glass transition temperature substrates (such as many polymers or organic substrates) require metallizations to form at curing temperatures even lower than the sintering temperature of gold and silver nanoparticles. These metallizations must also exhibit low electrical resistivity (smaller than 10-4 -cm). One application of such low-curing PAGE 23 Research in Silver Nanoparticle Synthesis Using the PVP -Protection Mechanism PAGE 24 PVP Protection Mechanism PAGE 25 sp sp sp PAGE 27 Silver Nanoparticle Reduction Systems The Polyol Process PAGE 29 Formaldehyde Reduction PAGE 34 Other Silver Nanoparticle Synthesis Reactions PAGE 38 Other Nanoparticle Systems PAGE 41 Current Silver Printing Applications PAGE 42 Pad Printing PAGE 45 Screen Printing PAGE 46 Inkjet Printing V = 4/3r3 V r PAGE 48 Review of Printing Methods Biocompatibility of Various Silver Compounds and Particles PAGE 49 General Health Effects Silver Compounds Silver and silver alloys PAGE 54 Studies of Specific Silver Exposure type dose manner of silver absorption or method of silver intake. metallic, high dose, ingested Silver acetate gum PAGE 55 Food -grade silver foil PAGE 56 Solid silver biomedical implants PAGE 57 Application of Biocompatibility Analysis to E -pills PAGE 59 Ink Preparation SNPs below 200 nm Relatively high solution molarity No non-biocompatible elements or compounds Re agents were to be low cost Reaction time was constrained to be less than 3 hours Final PVP content in SNP ink was to remain below 5% Ink from SNPs had to show good printability SNP in k should be re -suspendable in a variety of solvents SNPs should be stable and suspendable for extended periods PAGE 60 Basic Ink Synthesis All reaction steps are t o be performed in a fume hood due to toxic volatile compounds. PAGE 63 Analysis Techniques Transmission Electron Microscopy PAGE 64 Scanning Electron Microscopy Thermal Gravimetry PAGE 65 Particle Size Analysis Techniques Four -Point Probe PAGE 66 Rs = 4.532(V/I) Rs V I 4.532 Current Voltage Analysis Atomic Force Microscopy PAGE 68 Visual Observations PAGE 72 Inquiry into Visual Observations Effects of PVP Amount PAGE 78 Coil Confo rmation Importance PAGE 83 l n l PAGE 84 Solution Colors PAGE 86 Other Observations PAGE 87 Experimental Desi gn PAGE 89 Microtrac Nanotrac Results PAGE 91 DOE Repeatability PAGE 95 Statistical Analysis of DOE i i j PAGE 98 TEM Images PAGE 109 Summary of DOE Results Bimodal PVP MW Reaction Systems and Effects on SNP Properties PAGE 112 CPSC for SNPs PAGE 116 TGA of SNPs PAGE 119 TEM Im ages of SNPs PAGE 123 Electrical Resistivity of SNPs PAGE 128 SEM Images of Cured SNPs PAGE 133 Summary of Bimodal PVP MW SNPs Explanation of Electrical Resistivity of SNPs Cured at Temperatures Below Their Sintering Temperature PAGE 134 Current Voltage Analysis of SNP Thin Films PAGE 135 -1.5E-08 -1.0E-08 -5.0E-09 0.0E+00 5.0E-09 1.0E-08 1.5E-08 -6-4-2 0246 Voltage (V) Current (I) PAGE 136 -1.5 -1 -0.5 0 0.5 1 1.5 -3 -2 -1 0 1 2 Voltage (V) Current (A) Atomic Force Microscopy of SNPs PAGE 137 stiffer surfaces are distinguished by a large phase shift with abrupt edges PAGE 140 Summary of Electrical Resistivity of SNPs Cur ed at Temperatures Below Their Sintering Temperature PAGE 141 Printing of SNPs PAGE 142 Conclusions PAGE 144 Future Work PAGE 147 International Journal of Multiphase Flow Clinical Therapeutics Applied Physics Letters. Materials Chemistry and Physics. Materials Chemistry and Physics. Food Additives and Contaminants Macromolecular Rapid Communications Journal of Psychiatry Neuroscience. Annals of Occupational Hygiene. Clinical Therapeutics. Journal of Toxicology: Clinical Toxicology. Drugs Aging. PAGE 148 Molecular Crystals and Liquid Crystals. Critical Reviews in Toxicology. Nanotechnology. Nanotechnology. Advanced Functional Materials. Chemistry of Materials. Surface Science Chest. Journal of the American Medical Association. Philosophical Magazine B Journal of Electronic Materials. Analytical Chemistry PAGE 149 Langmuir. Colloids and Surfaces A: Physiochemical and Engineering Aspects. Journal of the European Ceramic Society. Coloration Technology. Journal of Materials Science Biosensors and Bioelectronics. Colloids and Surfaces A: Physiochemical and Engineering Aspects Journal of Colloids and Interface Sciences. Spectrochimica Acta, Part A: Molecular and Biomolecular Spectroscopy. Chemistry of Materials. Langmui r Langmuir PAGE 150 Materials Chemistry and Physics Pediatrics. Journal of Physical Chemistry Biomedical Cir cuits and Systems Conference, 2007 Journal of Solid State Chemistry. Philosophical Magazine Letters | |||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
