Resolving key manufacturing challenges in flip chip QFN package

Abstract

FC QFN package integrates a flip chip interconnect in a QFN body and combines the electrical efficiency of the flip chip interconnect and thermal efficiency of the QFN package. Other advantages include shorter assembly cycle time vs wirebonded QFN and small chip-to-pkg ratio closest to WCSP in terms of package footprint. The versatility of the flip chip QFN package opens new markets with applications on power management and DC-to-DC converters. Although advantageous as a package, the interconnect and package combination introduces several challenges due to its unique design features. This paper enumerates the manufacturing challenges of flip chip QFN associated with its unique package construction features and their possible solutions to the challenges by selecting the correct materials, defining design rules and performing process optimizations.