BGA封装结构热黏弹塑性的双尺度分析

将倒装焊底充胶BGA封装结构简化为含有非完全(单层)周期性微结构的多层板,基于均匀化理论,焊料采用统一型Anand黏塑性本构模型,建立了一种非完全周期结构的热黏弹塑性双尺度分析方法.通过Rayleigh-Ritz法,采用高阶逐层离散模型,耦合解析求解了热循环载荷作用下的宏、细观问题,确定了焊球的热应力应变行为.通过与有限元方法的结果对照,验证了该分析方法是简洁、有效的.算例结果显示,温度载荷、胶层厚度等是影响焊球热黏弹塑性响应的主要因素.

Double-Scale Analysis of Thermal Elastic- Viscoplasticity of BGA Packaging

The BGA packaging of flip-chip assembly with underfill was simplified into a multilayer board with imperfect periodical microstructure. Based on the homogenization theory with the Anand's unified viscoplastic constitutive model applied to the solder, a double-scale method was proposed to analyze the thermal elastic-viscoplasticity of this improper periodical microstructure. Then, the high-order discrete model was introduced layer by layer via the Rayleigh-Ritz method to analytically solve the problem of BGA under thermal cyclic loads microscopically and mesoscopically, thus determining the thermal stress and strain. The analytic method was verified simple and effective in comparison with FEM results. The result of a numerical example showed that the thermal load and thickness of glue underfill are the main influencing factors on the responses of thermal elastic-viscoplasticity of BGA in soldering.