Capillary design contribution to the bonding process quality of NiPd-PPF leadframes with Cu & PdCu wires

Package footprint reduction, environmental protection law compliance and manufacturing cost reduction constrains are moving the semiconductor industry toward the mass adoption of Quad Flat Non-leaded packages (QFN), Pre Plated Frames (PPF), and Cu based bonding wires. On the one hand, these chip packaging technologies enable compliance with these objectives, yet on the other hand they present new challenges to assembly houses and IC package manufacturers. This paper will discuss the influence of the capillary design, its material improvements and bonding process factors on the main challenges of bonding Cu and PdCu wires on NiPd-PPF leadframes, including QFNs. These challenges include low wedge bond strength, wedge bond deterioration over time, small wedge bond process window.