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封装形式的差异性对产品可靠性具有重要影响。基于有限元法,对比分析了薄型四方扁平封装(LQFP)和载体外露薄型四方扁平封装(eLQFP)在室温和回流焊温度下的翘曲、芯片和粘片胶的应力水平以及各材料界面应力分布。研究表明,LQFP的翘曲比eLQFP的大,但芯片和粘片胶上的最大应力无明显差别;eLQFP在塑封材料与芯片有源面界面的应力水平比LQFP的大;eLQFP在芯片与粘片胶界面、粘片胶与芯片载体界面的剪切应力比LQFP的大,但eLQFP在芯片与粘片胶界面、粘片胶与芯片载体界面的剥离应力比LQFP的小;eLQFP在塑封材料与芯片载体镀银区界面的应力水平高于LQFP的应力水平,由于塑封材料与镀银芯片载体的结合强度弱,eLQFP更易发生界面分层。
Differences in package form have a significant impact on product reliability. Based on the finite element method (FEM), the warpage of the thin quad flat package (LQFP) and carrier-exposed thin quad flat package (eLQFP) at room temperature and reflow temperature were compared and analyzed. . The results show that the warpage of LQFP is larger than that of eLQFP, but there is no significant difference in the maximum stress between chip and adhesive. The stress level of eLQFP at the interface between plastic material and chip is larger than that of LQFP. However, the shear stress of the interface between the adhesive and the chip carrier is larger than that of the LQFP. However, the eLQFP has a smaller peel stress than that of the LQFP at the interface of the chip and the adhesive. The release stress of the eLQFP between the plastic material and the chip The stress level at the silver-plated interface of the carrier is higher than the stress level of LQFP. Due to the weak bonding strength between the encapsulant and the silver-plated chip carrier, eLQFP is more likely to delaminate at the interface.