Evaluation of Lead Free Solder Paste Materials for PCBA

Most of electronic components on a printed circuit board assembly (PCBA) are surface mount components assembled using solder paste material. Having a good solder paste material is very critical for having a high yield and reliable product. There is a strong correlation between the SMT defects to solder paste quality 1 , but there is limited published information on the evaluation procedure and requirements for a good solder paste material. This paper discusses the strategy and methodology for selecting a good lead-free solder paste material for volume manufacturing uses. A statistical and methodological evaluation approach will be addressed in details. It shows how to screen the solder paste candidates for quality using printability tests, slump test, solder ball test and wetting tests and how to select a robust solder paste material using a design of experiment. The performance of lead-free no clean solder paste, lead-free water soluble solder paste, halogen containing solder paste and halogen free solder paste will be compared. Characteristics and requirements of a good lead free solder paste material are also outlined.