Moisture induced vapor pressure and weakened interfacial strength in CSP packages
The reflow temperature of plastic electronic packages may rise to as high as 220℃ or higher. Mechanical properties of polymeric materials are highly sensitive to temperature and strain rate. If a spherical volume of material containing a (concentric) spherically shaped micro-void, then popcorn failure in plastic electronic packages can be gained by studying the unstable growth of an initially spherical void in a class of generalized neo-Hookean materials subject to combined moisture-induced vapor pressure and remote thermal stress. A nonlinear and non-monotonic relation between applied stress and the void volume fraction was described by the Guo-Cheng model. Analysis of the radial equilibrium problem shows that there exists a critical traction, which defines the onset of unstable void growth. The presented results show some perturbation parameters significantly lower the critical stress levels for unstable void growth.
Zhi-gang Li Xiao-yan Niu Li-qing Meng Xue-feng Shu
Institute of Applied Mechanics, Taiyuan University of Technology, Taiyuan 030024, China
国际会议
The 5th International Conference on Nonlinear Mechanics(第五届国际非线性力学会议)
上海
英文
212-215
2007-06-11（万方平台首次上网日期，不代表论文的发表时间）