Lead Free Paste with under 3um Solder Particles for Fine Pitch C4 bumping and pre-coating solder applications - (PPT)

摘要

Super fine particle with an average particle size of under 3um (D50) was achieved by chemical reduction method. Printed paste shape, bump height, coplanarity and missing bumps of super fine particle paste were better than those of gas atomized paste. From measurement result of paste rheology, it was found that the filling characteristic of Super fine particle paste was better and the printed paste shape of Super fine particle hardly slumped. By applying Super fine particle to pre-coating paste, better coverage and flatter solder layer were formed. To conclude these, it is thought that super fine particle is critical for finer pitch assembly and formation of pre-coating solder layer.