COMPARING MANUFACTURING PERFORMANCE OF STAGGERED AND INLINE SECOND BOND FINGERS FOR WIRE BONDED BGA SUBSTRATES
Authors: Jeannie Miller, Mark Gerber and Christina Corona Company: Motorola-Semiconductor Date Published: 6/12/2001
Advanced Packaging Technology
Abstract: This paper discusses the manufacturing performance of staggered versus inline second bond finger designs on wire bonded BGA substrates. As greater silicon functionality needs drive I/O counts higher and customers demand smaller package outlines, the need for substrate designers to utilize a staggered bond finger formation is increasing. This substrate bond finger design method allows for a higher number of bond fingers to be placed around the perimeter of the die while minimizing the wire length and providing a smaller package outline. Recent improvements in organic substrate technology allow for very fine pitch bond fingers and designers now have a choice in using various bond finger formations for finer pitch designs. However, several questions regarding the benefits of using staggered versus inline have been raised. These include trade-offs between wire sweep challenges, associated with both design methods, as well as process cycle time impact associated with the wire bond process. This report discusses an evaluation that compares these two different second bond finger designs and the interactions of the wire bonding and encapsulation processes. In addition, this evaluationinvestigates multiple mold compounds and their impact on the process issues associated with these substrate bond finger designs. The information used from this evaluation can help determine a preferred substrate design for future products that have smaller die sizes with a high number of I/Os.