Line-structured laser scanning measurement system for BGA lead coplanarity

This paper presents line-structured laser scanning measurement technology in SMT-based BGA chip leads' coplanarity. An experimental measurement system is put forward. A corresponding mathematical model and contact-datum-plane assessment method on BGA chip lead coplanarity is established. A study of optical image splitting and splicing technology is made illustrating the capability of higher resolution. The experimental studies on a 20/spl times/20 BGA chip is carried out; the inaccuracy error of the measurement system is 2/spl sigma/=0.033 mm.