Papers by Author: Nuo Bao

Abstract: In order to obtain a better filling way with suitable adhesive to enhance the reliability of 3D PLUS solder joints. Finite element analysis of random vibration method was carried out. By means of the method, the effect of filling way on the stress distribution in solder joints was investigated under the condition of two types adhesives 55/9 and GD414. Stress distribution and its maximum value of 3D PLUS solder joint at peak time were acquired. Comparative analysis of the maximum stress between under filled adhesive and side filled adhesive with 55/9 or GD414 respectively. The results showed that under filled adhesive 55/9 can effectively improve the solder joint stress.

Abstract: Thermal cycling was applied to assess the effect of tin-lead solder 63Sn37Pb and lead-free solder 95.5Sn3.8Ag0.7Cu on the reliability of 3D PLUS solder joints. Nonlinear finite element method and viscoplastic Anand model were used to evaluate the stress and strain distribution and dangerous position of solders under the thermal cycling condition. The law of solder joints stress and plastic strain were finally obtained and showed significant cyclical changes. The stress and strain emerged the trend of accumulated enhancement with the process of time, then ultimately stabilized. Comparing two curves of equivalent stress and plastic strain obtained from lead-free and tin-lead solder, it was found that the reliability of 95.5Sn3.8Ag0.7Cu was better than that of 63Sn37Pb.