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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 use of lead-free solder, the reflow soldering temperature affects the quality and reliability of the molded part. For the actual LQFP device, a three-dimensional model was established by using finite element software. The deformation and thermal stress distribution of plastic encapsulated devices in moisture diffusion and reflow were analyzed. The effects of plastic encapsulation parameters and fine cracks on delamination influences. The results show that under the hot and humid loading, the top corner of the plastic encapsulated device tends to warp; the interface between the chip and the encapsulant is easily delaminated, which leads to device failure.