Addressing the Broken Wire Issue during the Assembly Manufacturing of QFN Leadframe Device

The integrity of the assembly wirebond process’ 2nd bond poses a big challenge for semiconductor manufacturing of quad-flat no-leads (QFN) devices, particularly on multiple wires on a lead. These devices are vulnerable to induce or obtain broken wire at heel defect. This type of defect is an abnormality in the formation of the stitch, mostly a crack or fracture seen on the facade of the stitch. Normally, it happens when there is too much vibration or transfer of ultrasonic generator (USG) power combined with high bonding force on 2nd bond. In the case of leads with common wires, broken wire at heel could also happen through excessive USG application resulting to transfer of resonance on adjacent wires. This paper presents a better understanding and analysis done to provide an adequate and appropriate solution to broken wire at heel issue.