| Summary: | 博士 === 國立成功大學 === 材料科學及工程學系碩博士班 === 98 === By utilizing the drastically reduced melting temperature of nano-sized particles (NPs), one of recent developments in microelectronic packaging is to manufacture highly conductive interconnections with metallic nanoparticle deposits subjected to a low temperature process. With the emerging technology of inkjet printing system, nano-size metallic NP suspensions can be applied to fabricate electrical line patterns without using conventional lithography. For the transportation of power and signal, the nanoparticle deposits should be consolidated and well jointed with the contacts of the devices. This study systematically investigated the low temperature melting, solidification and alloying of Au, Ag and Ag3Au nanoparticle deposits. The interaction between the metallic NPs and electronic substrates will be also explored. By doing so, the phase transformation issues such as the supercooling, latent heat difference, and driving force for solidification resulted from nanosized effects will be well understood.
This presenting thesis can be divided into three parts: First, the low temperature melting and subsequent solidification of Au nanoparticles was investigated. The temperature of phase transformation was examined by thermal analyses, microstructure evaluation, resistance measurement and surface plasma resonance shifts. Through monitoring the evolution of diffraction peaks as function of temperature using in situ synchrotron X-ray diffraction, the low temperature melting behavior of gold nanoparticles was further manifested.
Secondly, the alloying behavior between gold nanoparticle deposits and metallic substrates due to nano-sized effect was examined. The differences in interfacial products and adhesion strength between gold nanoparticles deposits and those of sputtered gold thin-film were studied by means of SIMS, ESCA and pull-off test. In addition, the chemical shifts of the reaction products proved the phenomenon of low temperature alloying.
In the third part, the interfacial reactions between nanoparticle deposits of different compositions (Au, Ag and Ag3Au) and metallic substrates of Ag, Cu and Ni were systematically investigated. It was examined that the phase and thickness of reaction layers were not only determined by the composition of the deposited nanopartilces but the differences of physical and chemical properties between the nanoparticles and substrate materials, including lattice mismatch, electronegativity difference and mixing enthalpy of the alloying systems involved. From the viewpoints of metallurgical and thermodynamic, the nano-sized induced successive behaviors of low temperature melting, alloying and solidification were demonstrated in this study.
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