微尺度CSP焊点温振耦合应力应变有限元分析

Finite-element analysis for temperature-vibration coupled stress and strain of a microscale CSP solder joint

建立了微尺度芯片尺寸封装(CSP)焊点三维有限元分析模型,对模型进行了热结构耦合分析和温振耦合分析,获得了微尺度CSP焊点应力应变分布结果;对比分析了微尺度CSP焊点与常规尺寸CSP焊点的应力应变分布;分析了不同焊料、焊盘直径和焊点体积对微尺度CSP焊点应力应变的影响。结果表明:温振耦合条件下,微尺度CSP焊点内应力应大于常规尺寸CSP焊点应力应变;在SAC305、SAC387、63Sn37Pb、62Sn36Pb2Ag四种焊点材料中采用SAC387的焊点最大应力最大;焊点最大直径由105μm减小至80μm时,微尺度CSP焊点内应力应变呈现出减小的趋势;焊盘直径由80μm减小至60μm时,微尺度焊点内应力应变呈现出增大的趋势。

3 D finite element analysis models for micro-scale chip scale package（ CSP） solder joints were established. According to the thermal-structural coupling analysis,temperature-vibration coupled analyses were done for models. Stress and strain distributions of micro-scale CSP solder joints were obtained. Stress and strain distributions of micro-scale CSP solder joints were compared with those of conventional scale CSP solder joints. Effects of different solder materials,pad diameter and solder joint volume on stress and strain of micro-scale CSP solder joints were analyzed. The results showed that stress and strain of micro-scale CSP solder joints are larger than those of conventional-scale CSP solder joints under the temperature-vibration coupled condition; The maximum stress of solder joint using material SAC387 is larger than that using material SAC305,63 Sn37 Pb and 62 Sn36 Pb2 Ag,respectively; when the maximum diameter of solder joint decreases from 105 μm to 80 μm,stress and strain of micro-scale CSP solder joints gradually decrease; when pad diameter decreases from 80 μm to 60 μm,stress and strain of micro-scale solder joints gradually increase.