Properties of Lead Free Alloy and Performance Properties of Lead Free No-Clean Solder Paste

摘要

This paper is targeted to the electronic assembler who is using lead free mi-clean solder pastes or want to use lead free no-clean solder pastes. Lately more attention has been paid to the development of a lead free no-clean vehicle system and no-clean solder pastes. This paper will discuss the development of a no-clean solder paste system with the unique needs of the 214―220℃ melting point range lead free alloys. It includes: 1. The selection of lead free alloy and its properties comparison to Sn63 powder (creep resistance at room temperature, mechanical properties: tensile strength, yield strength, Young's modulus, elongation and hardness. SEM testing for cross section joints and X-ray for BGA voiding), 2. Characterizations of lead free no-clean solder paste by Brookfield viscosity, Malcom viscosity, solder ball on ceramic, tack (initial, 4 hrs, 8 hrs, 24 hrs, 48 hrs), printing, print life and reflow, 3. reflow profiles established using our TGA profile prediction method.