Adhesion enhancement of Pd plated leadframes

A surface treatment method for Pd plated leadframes to improve its adhesion to die attach materials and mold compounds is developed. It was found that regardless of the structures of Pd plated leadframes, the adhesion could be increased by up to ten times, compared with untreated Pd plated leadframes. With the improved adhesion, TQFP100 packages with the treated Pd leadframes passed the JEDEC Level 1 in moisture sensitivity test and 1000 cycles in thermal cycling without any delamination. In contrast, severe interfacial delamination was found in JEDEC Level 3 moisture sensitivity test, or after 100 cycles in thermal cycling for all of TQFP 100 packages with pristine Pd leadframes. In addition, the wire bondability of treated Pd leadframe is shown to be compatible with the packaging assembly process