EFFECT OF CHIP DIMENSION AND SUBSTRATE THICKNESS ON SOLDER JOINT RELIABILITY OF PLASTIC BGA PACKAGE
Author: Shi-Wei Ricky Lee Company: The Hong Kong University Date Published: 9/10/1996
Surface Mount International
Abstract: This paper presents a nonlinear numerical study to investigate the effect of chip dimension and substrate thickness on the solder joint reliability of plastic ball grid array (PBGA) packages. The package under investigation was a 225-pin full-grid PBGA assembly. The diagonal cross-section of the PBGA together with the printed circuit board (PCB) was modeled by plane-strain elements. A uniform thermal loading was applied and the solder joints were stressed due to the mismatch of coefficient of thermal expansion (CTE) and constructions of the PCB assembly. The effective stress and accumulated plastic strain of solder balls against various chip dimensions and substrate thicknesses were evaluated as an index for the reliability of solder joints. The results of this study are helpful for electronics packaging engineers to optimize the geometry of plastic ball grid array packages. Keywords: plastic ball grid array, solder joint, reliability.