Ce对CSP36器件SnAgCu焊点可靠性影响研究

Effect of Rare Earth Ce on the Reliability of SnAgCu Solder Joints in CSP36 Device

采用有限元法研究了CSP36器件Sn3.8Ag0.7Cu和Sn3.8Ag0.7Cu0.03Ce两种无铅焊点应力-应变响应,研究Ce对无铅焊点可靠性的影响.结果表明,在交变的温度载荷条件下,PCB板呈现明显的翘曲状态,最大应力集中在拐角焊点的上表面,该部位是焊点潜在的裂纹萌生源。SnAgCu焊点的应力-应变明显高于SnAgCuCe焊点,主要是因为第二相颗粒对基体组织位错的定扎的原因。焊点疲劳寿命预测发现CSP36器件SnAgCuCe焊点疲劳寿命明显高于SnAgCu焊点,证明了Ce显著提高CSP36器件SnAgCu焊点的疲劳寿命。

Finite element method was used to study the stress- strain response of Sn3. 8Ag0. 7Cu and Sn3. 8Ag0. 7Cu0. 03 Ce solder joints in CSP36 devices,which can indicate the effect of rare earth Ce on the reliability of lead- free solder joints. The results show that warp of the PCB board can be found during thermal cycles loading,and the maximum stress can be found in the top surface of the corner solder joints,this location may be the headstream of cracks. The stress- strain of SnAgCu solder joints is higher than that of SnAgCu Ce solder joints,which can attribute to the pining dislocations of second phase particles in the matrix microstructure. In the fatigue life prediction of solder joints,the fatigue life of SnAgCu Ce solder joints is higher than that of SnAgCu solder joints,which demonstrate that the rare earth Ce can enhance the fatigue life of SnAgCu solder joints in CSP36 devices.