Research On Electronic Packaging Interconnection Materials

With the fast development of integrate circuits manufacturing technology, micro-connection material and process is becoming more and more important. The harm of leaded material used in electronic industry to human and environment has drawn huge attention, so lots of lead-free materials have been developed. The research of two kinds of lead-free micro-connection material, Sn96.5-Ag3.0-Cu (SAC305) solder bumping and electronic conductive adhesive (ECA), were conducted in this paper.Bumping technology has been widely used in consuming electronic devices. But for fine pitch bumping, there are many problems to solve such as low reliability, high cost and complicated process. Solder will acquire liquidity when heated above the melting point and fusion of melted droplets of solder will happen due to the surface tension. The rheological behavior of fused droplets of solder can be used to form micro-bumps spontaneously on the prepared pads where the fused solder could be immersive. The viscosity of some thermoplastic resin when heated will decrease to a level that is proper for the melted solder droplets to flow and fuse. In this paper, SAC305solder powder was mixed with this kind of resin in room temperature. The proportion of the two components was well designed to make sure the viscosity of the system was not too small or too big. A little rosin was added into the system as a deoxidizing agent to reduce the oxide layer on solder droplets and solder pads as well. The mixture was then printed without masks onto prepared PCB substrates with copper pads on them. The reflow process was conducted with designed temperature curve in a reflow oven.500μm,300μm,200μm,100μm pitch bump arrays were prepared using this material.The popular commercial ECAs have bad mechanical properties and high resistivity. Benzoxazine thermoset resins are the reaction products of an amine, a phenol and formaldehyde with excellent properties such as low water absorption and high temperature resistance. Benzoxazine and conventional epoxy resin was mixed as the substrate resin of ECA in this paper. Curing behavior and the thermo properties of the mixed resin was researched. Silver nanoparticles surface functionalized by organic dicarboxylic acid, micrometer silver flake and the mixed resin system mentioned before were used to prepare high performance ECAs. The high curing temperature of the resin system can provide higher sintering temperature for the silver nanoparticles filled in the ECA, so the silver nanoparticles can be sintered better and the ECA could have a lower electronic resistivity. ECA films with the resistivity of2～5×10-5Ω·cm was prepared using this resin system.