LGA pre Bump Process Elimination

Land Grid Array (LGA) is a grid array package like Ball Grid Array (BGA) package with terminal pads on bottom surface without solder ball attach to its terminal pads. The electrical connections of LGA are made through bottom terminal pads surface to the terminal pads of Printed Circuit Board (PCB). In Printed Circuit Board Assembly (PCBA) manufacturing process, the typically approach to mount LGA package to PCB are with pre bump LGA and without pre bump. The advantage of pre bump is to have more process margin for improving solder joint (SJ) forming with minimum solder defect such as void, open, and bridging. However, pre bump require additional processes which resulted in negative impact to manufacturing cost and capacity. This paper shares the uniquely designed of LGA stencil aperture “windowpane” to achieve equivalent SJ forming quality without pre bump. With this improvement, the LGA without pre bump can be mounted to PCB using typical Surface Mount Technology (SMT) process along with all the rest of the SMT component.