A Parameter Study for the Design Optimization to Relieve Pattern Stress of PCB under the Temperature Cycling Condition

The main objective of this research is to propose an optimized design to relieve pattern stress in the PCB. Numerical simulations were performed to quantitatively evaluate pattern stress according to solder ball properties, pattern width and pattern direction. Correlations between these parameters and pattern stress were also presented. This paper aims to present a design for mitigating PCB pattern stress through the investigation of parameters. To achieve this goal, parameters such as solder ball properties, pattern width and pattern direction that can affect pattern reliability were selected. Numerical simulations conducted in order to analyze major factor affecting pattern stress under the TC condition. The materials of the solder ball were compared by applying relatively low modulus and high modulus. Also, the pattern widths were selected as 0.7x, 1.0x and 1.3x considering the practical range. The parameters of the pattern direction were set to 0 degree, 45 degree and 90 degree. The pattern stress is minimized when the solder ball modulus is low, the pattern width is large, and the pattern angle is 45 degrees from the center line. These parametric studies can be used to design the PCB pattern to minimize the pattern stress.