Stress Analysis of Multilayered Printed Circuit Board under Mechanical Loading
Authors: Jia-Shen Lan and Mei-Ling Wu Company: National Sun Yat-Sen University Department of Mechanical & Electron-Mechanical Engineering Date Published: 4/30/2012
Abstract: With the technological breakthrough that has been made in real applications, mechanical loading has become very important in the reliability assessment of modern electronic systems. This research demonstrates that the assessment approach can be successfully applied to the design of a ball grid array package with a more accurate assessment model for fatigue life under mechanical loading. Previous research has mostly focused on thermal cycling analysis; however, most modern portable electronic products used in automobiles, personal digital assistants (PDA), and aircraft have to endure extreme environments that involve not only thermal but also mechanical loading conditions. Finally, the primary focus of this research is the issue of how accurately the assessment methodology is able to estimate the fatigue life of the ball grid array solder joint under mechanical loading. Based on the mechanical issue, we discuss the solder joint reliability, which is the interconnection between integrated circuit (IC) and printed circuit board (PCB). This paper used different kinds of solder joints; analyzing microelectronic packaging endured stress on the solder joint and deflection with the finite element method (FEM) simulations. Analyses of variance were used to detect significant differences among varieties of solder joint. Our analysis indicates three main points: 1) The report analyzed stress on the solder joint and deformation on the board when bending moment is applied on multilayers PCB; 2) The lead-free solder was stiffer and more brittle than the lead solder. In this finding, we were able to improve this situation. The results show a clear and strong relationship between solder joint of material and two plates of material, which are IC and PCB; 3) There are two pad designs, solder mask defined (SMD) and Non-Solder mask defined (NSMD), which have an effect on destructive solder joint level and board level. This condition occurs as a result of pad cracking. The obtained results can be of help in designing microelectronic packaging and may lead to a better understanding of the subject of this study.
Finite element method, multilayers printed circuit board, lead-free solder, solder mask defined, non-solder mask defined, pad cracking