Rework in Surface Mount Technology (SMT)

摘要

This paper describes the most popular rework methods implemented in SMT. By highlighting the pros and cons of each method, the focus is mainly given to hot-air reworking and its advantages. An extensive thermal analysis of hot-air reworking is given to prove the superiority of convection over conduction and radiation. This thermal analysis of surface mount assemblies is based on the actual studies done at CAE Electronics on the Space application (Canada robot arm ). Furthermore, the rework procedure on an automatic and a manual rework station for the Space application is partially discussed. This procedure shows how to rework Surface Mount Components (SMCs) with respect to all the constraints- rate of rise, excessive heat, dwell time, etc.Finally, several heat profiles indicate that hot-air should not only be used in soldering but also in reworking of Surface Mount Components(SMCs).