Investigation on rheological behavior and jet printing process of the solder pastes

Jet printing technology is more suitable for Surface Mount Technology (SMT) to develop in high density and flexible production compared with traditional stencil printing. In recent years, domestic and foreign scholars have carried out a lot of research work in the design of lead-free solder paste components, jet printing equipment and process, and made some progress. However, due to the control theory of jet printing performance has not yet been established, which has affected the popularization and application of jet printing technology in the electronic assembly field. Investigation of solder paste used for jet printing technology and establishing the relationship between materials composition and jet printing performance will provide a reference for the design of a wider range of solder pastes suitable for jet printing technology. In this work, materials containing Sn-58Bi solder pastes were chosen, and the effects of temperature and solid phase contents on the rheological properties of viscosity, thixotropy, viscoelasticity of solder pastes were studied systematically. high speed photography method was used to track the printing process, and the morphology of the printing points was observed by VHX-5000 Superhigh magnification lens zoom 3D microscope. A certain relationship between rheology and jet printing performance of solder paste was established. The quality of the solder paste droplets was evaluated by the ratio of height to diameter of solder paste droplets.