共晶焊后热敏电阻的应力分析及优化  

Stress Analysis and Optimization of Thermistors After Eutectic Soldering

作　　者：李长安 牛玉秀 全本庆 关卫林 LI Chang'an;NIU Yuxiu;QUAN Benqing;GUAN Weilin(Accelink Technologies Co.,Ltd.,Wuhan 430205,China)

机构地区：[1]武汉光迅科技股份有限公司,武汉430205

出　　处：《电子与封装》2023年第9期1-4,共4页Electronics & Packaging

摘　　要：为了研究与解决热敏电阻在共晶焊后阻值变大的问题,采用扫描电子显微镜(SEM)观测失效的热敏电阻,发现其内部有裂纹。采用有限元分析法分析热敏电阻经过共晶焊后产生的应力,结果表明,最大应力的位置与裂纹位置基本一致,最大应力的方向与裂纹方向正交,这说明裂纹是由应力引起的。分析了热敏电阻上最大应力与焊料厚度的关系,结果表明,焊料越厚,则热敏电阻在共晶焊时产生的应力越小。通过验证试验可知,采用适当加厚的焊料对热敏电阻进行共晶焊,共晶焊后热敏电阻的外观良好,没有裂纹发生,且阻值没有增大。因此,可采用加厚焊料的方法防止热敏电阻开裂。In order to study and solve the problem that the resistance values of thermistors increase after eutectic soldering,the failed thermistors are observed by scanning electron microscope(SEM)and cracks are found in them.The stresses generated by the thermistors after eutectic soldering are analysed by the finite element analysis method.The results show that the locations of the maximum principal stresses are basically consistent with the locations of cracks,and the directions of the maximum principal stresses are orthogonal to the directions of the cracks,which indicate that the cracks are caused by stresses.The relationship between the maximum principal stresses on the thermistors and the solder thicknesses is analyzed.The analysis results show that the thicker the solder thicknesses are,the smaller the stresses generated by the thermistors during eutectic soldering.Through the verification test,it can be seen that using appropriately thickened solder for eutectic soldering of thermistors,the appearances of thermistors after eutectic soldering are good,there are no cracks,and the resistance values don't increase.Therefore,the thermistor cracking can be prevented by increasing the solder thickness.

关 键 词：热敏电阻 共晶焊 应力 有限元分析法 

分 类 号：TN306[电子电信—物理电子学] O302[理学—力学]