EFFECT OF TEST BOARD DESIGN ON THE 2ND LEVEL RELIABILITY OF A FINE PITCH BGA PACKAGE
Author: Robert Darveaux Company: Amkor Electronics Date Published: 8/23/1998
Surface Mount International
Abstract: The impact of PCB design on solder joint fatigue life for fine pitch BGA packages is characterized. Board thickness, pad configuration (solder mask defined, SMD, vs. non-solder mask defined, NSMD), and pad size were variables in the study. Solder joint fatigue life was 1.2X to 1.6X longer for 0.9mm thick test boards compared to 1.6mm thick boards due to a lower assembly stiffness. Assemblies with NSMD test boards had 3.1X longer fatigue life than SMD test boards. A pad design of .45mm / .30mm (mask opening / pad size) gave 1.1X better fatigue life than .43mm / .33mm due to a better solder joint fillet around the copper pad.