Study On The Preparation Of Au/pt Powder Used For Thick Film Metallization Of Aln

Precious metal powders have a very wide range of applications in electronic industry as a function phase in thick film due to their excellent electrical properties and chemical stability. The properties of particles, such as particle size distribution and morphology, are key to the electrical, mechanical properties and weld ability of thick film. In our experiment, Uniform gold, platinum and their alloy particles with narrow particle size distribution are synthesized by polyol process and chemical reduction ways. The solder ability of metalized film after applying Au/Pt composite in thick film for AlN is also discussed.Au powders with uniform distribution and nearly spherical is synthesized using EG as reducing agent and PVP as dispersant in polyol process; Au having different size distribution and spherical morphology is reduced by sodium citrate using PVP as dispersant in 60℃and 100℃respectively. Au prepared use PEG400 as dispersant in polyol process has larger particle size (400nm) and irregular spherical shape, however, Pt reduced by this method is in nanoscale.Au/Pt alloy powder in nanoscale is co-synthesized by using NaBH4 with strong reducibility and PVP as dispersant; For co-reduction of Pt and Au using PEG400 as dispersant in polyol process, Au is coated by Pt nanoparticles. Au/Pt composite powder with this structure could be be easy to realize Au/Pt alloying when applied to thick film.Use Au/Pt composite powder and the Au/Pt alloy powder as metal phase separately and choose CaO-B₂O₃-SiO₂-BaO and CaO-B₂O₃-SiO₂ as binder respectively to prepare thick film that has 70wt% Au/Pt, 5wt% glass and 25wt% organic vehicle. By XRD and EDS analysis, Au/Pt powder obtain good alloying and has good weld ability.