Measurement System for BGA Coplanarity

This paper presents a line-structured laser scanning system for measuring the coplanrity of BGA chip leads. The corresponding methematics model of the system is gived. And also a study of optical image splitting and splicing technique is constructed and used to improve the resolution of the system. Furthemore, a contact-datum-plane assessment method is established to evaluate the coplanarity of BGA chip leads. The experimental studies on a 20 × 20 array of BGA chip is carryed out, the inaccuracy error of the measurement system is 2σ= 0.033μm.