Thermo-mechanical behavior of ball grid packages with different solder ball grid patterns investigated through moiré interferometry Thermomechanisches Verhalten von Kugelgitterpackungen mit unterschiedlichen Lotkugelgittermustern, untersucht durch Moiré-Interferometrie

Abstract

Plastic ball-grid array (PBGA) package assembly comprises various materials with different thermo-mechanical properties, and the solder ball-grid patterns can significantly influence the package deformation and solder ball stress. This study utilizes moiré interferometry to investigate the deformation behavior of wire bonded plastic ball-grid array (WB-PBGA) packages under varying temperatures. Real-time moiré interferometry experiments were conducted to capture fringe patterns representing package deformation at different temperature stages. Experiments were conducted for three different wire bonded plastic ball-grid array packages with distinct solder ball array configurations: full grid patterns (WB-PBGA-FG) and perimeter patterns with/without central connections (WB-PBGA-PC/P). The analysis revealed considerable variations in thermal strain distribution and positioning of the critical solder ball within the package assembly, depending on the solder ball-grid pattern. Among these wire bonded plastic ball-grid array packages, WB-PBGA-P/C exhibited the most substantial bending deformation, experiencing the highest effective strain, which directly impacts solder ball failure. These findings emphasize the importance of solder ball-grid patterns in understanding the deformation behavior and reliability of WB-PBGA packages under varying temperature conditions.