散热强化型覆晶球栅数组封装组合体内的凸块之疲劳寿命研究 Investigation of Fatigue Life of Solder Bumps in a Thermally Enhanced FC-PBGA Assembly

Abstract

使用有限元素分析软件ANSYS建立一精确之三维有限元素模型，于温度循环负载下，针对散热强化型覆晶球栅数组封装体中的凸块之热机械行为进行模拟分析，接着，对凸块之疲劳寿命进行预测。这个散热强化型覆晶球栅数组组合体是基本型覆晶球栅数组封装体包封着封胶，接着在封胶上面黏附着一片铝质散热板，最后以锡球构装在印刷电路板上。凸块与锡球的材料是锡铅合金,本文以亚兰德模型来定义并描述其弹性、塑性及潜变行为。凸块之疲劳寿命预测是将模拟得到的凸块Von-Mise应变范围代入修正型Coffin-Manson疲劳寿命预估式，来预估凸块之疲劳寿命。本文报告了凸块应力、应变及疲劳寿命等机械行为。最后，进行参数化分析,讨论不同高分子组件与散热组件的设计参数对凸块疲劳寿命的影响。 In this paper, three-dimensional finite element analysis using the commercial ANSYS software is performed to study solder bump fatigue life for a thermally enhanced FC-PBGA (Flip-Chip Plastic Ball Grid Array) assembly subjected to temperature cycling. The thermally enhanced FC-PBGA assembly is a basic FC-PBGA package that is overmolded with molding compound, after which an aluminum heat spreader is adhered to the top of the molding compound and subsequently mounted on a PCB (Printed Circuit Board). In the simulation, all the solder bumps and the solder balls are modeled with nonlinear viscoplastic time and temperature dependent material properties based on Anand’s constitutive equation. Solder bump fatigue life is estimated by the widely accepted modified Coffin-Manson equation. The thermo-mechanical behavior of the solder bumps is presented. Solder bump fatigue life is analyzed by considering various design parameters of the polymer-based materials and the thermal enhancement components.