塑封器件回流焊与分层的研究

Research on delamination of plastic packaging device in reflow soldering

由于无铅焊料的应用,回流焊的温度提高影响了塑封器件的质量和可靠性。针对实际的LQFP器件,利用有限元软件建立三维模型,分析了塑封器件在潮湿环境中的湿气扩散及回流焊中的形变和热应力分布,并讨论了塑封料参数及细小裂纹对分层的影响。结果表明,在湿热的加载下,塑封器件的顶角易发生翘曲现象;芯片与塑封料界面处易分层,导致器件失效。

Due to the application of lead-free solders, the quality and reliability of plastic packaging devices are influenced by the increase of reflow temperature. A specified LQFP package was used as a demonstrator. The three dimensional model was established and the moisture diffusion in humid environment, deformation, thermal stress distribution of reflow soldering were analyzed by finite element software. The impacts of material parameters of molding compound and tiny crack on interface delamination were also discussed. The results show that the warping phenomenon is found at the apex angle of the device under the moisture and thermal load; delamination is easily produced in the interface between die and molding compound, and possibly leads to the device failure.