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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。
The stress-strain response of two lead-free solder joints, Sn3.8Ag0.7Cu and Sn3.8Ag0.7Cu0.03Ce, of CSP36 devices was studied by finite element method, and the effect of Ce on the reliability of lead-free solder joints was investigated. Temperature stress conditions, the PCB showed obvious warping, the maximum stress is concentrated in the corner of the upper surface of the solder joint, the site is a potential solder crack initiation source. The stress-strain of SnAgCu solder joints is obviously higher than that of SnAgCuCe solder joints, which is mainly attributed to the second-phase particles fixing the matrix structure dislocations. The fatigue life prediction of solder joints shows that the fatigue life of SnAgCuCe solder joints of CSP36 devices is significantly higher than that of SnAgCu solder joints, which proves that Ce significantly improves the fatigue life of SnAgCu solder joints of CSP36 devices.