Rheological characterization and jet printing performance of Sn-58Bi solder pastes

摘要

AbstractThe rheological character and jet printing performance of the lead-free solder paste (Sn–58Bi) with four solid phases were investigated. The rheology tests, containing oscillation test, creep recovery test, viscosity test and thixotropic loop test, were conducted by an Anton Paar MCR302 rheometer. Jet printing technology is a new packaging method with many advantages such as high precision, customization, low cost, etc. The jet printing test was carried out with the spray nozzle heated to 50 °C. From this study, it is found that the G″/G′ ratio of the pastes obtained by the oscillation stress test can influence the jet printing performance of the pastes. Paste 2 with the lowest ratio of G″/G′ can form the most complete hemispherical droplet. In addition, the solder paste with better liquid-like character at the nozzle and more solid phase property and surface tension when crashing on the base plate could be reverted to the hemispherical morphology easily. As the demand for pastes applied to jet printing increases, rheological measurement can assist with the research of the new high viscosity lead-free solder pastes.