Advanced QFN packaging with trace routing design

摘要

In this paper, a lead frame package with trace routing capability is proposed for advanced QFN package that has copper traces to connect with pads or dies, called routable aQFN package. Four packages were conducted to evaluate the trace routing capability. The first is wire bond type 11 mm ×11 mm 141 I/Os package with trace fan-out designs. The second is wire bond type 3.2 mm × 3.2 mm 48 I/Os package with trace fan-in designs. The third is flip chip bond type 8 mm × 8 mm package 288 I/Os with the combination of the trace fan-in and fan-out design. The last is flip chip bond type 6 mm × 6 mm package 25 I/Os with three dies by trace routing to connect die with die and under developing. Compared to aQFN package, a significant improvement in increasing I/Os, reducing wire sweep risk and be more flexible bond layer-out design can be obtained by choosing wire bond type routable aQFN. There are major advantages of flip chip type routable aQFN: more I/Os, multi-dies package and finer pitch bump layer-out. Currently, the trace routing capability is that 0.5mm pitch can escape 2 traces between pad and pad. The minimum line width and trace space is 50 um and 100 um, respectively.