Optimization of the Wire Bonding Process for Enhanced Thermomechanical Performance of Quad Flat No-Lead (QFN) Packages in Automotive Applications

This study investigates how local warpage and stress near the sawing lines of quad flat no-lead (QFN) packages, under stringent automotive conditions, influence the wire bonding process. A finite element model, validated through experimental measurements, was developed to quantify deformation and stress distributions along the cutting paths. Three lead frame strip designs—one row one block, multiblock, and one block—were comparatively assessed under both thermal and mechanical loads. Results show that the one row one block design can reduce local deformation by up to 70%–75% (e.g., $45~\mu $ m versus $159~\mu $ m) compared to the one block configuration, significantly mitigating alignment errors and fatigue risk. Concurrently, its peak local stress is about 212 MPa—a 70% reduction relative to the 708 MPa observed in the one block design. These combined improvements highlight the necessity of balanced structural design in sawing regions to enhance wire bonding stability. Overall, these findings provide a robust framework for optimizing QFN packages under stringent automotive conditions, particularly by refining wire bonding design.