Advances in fine pitch lead free assembly process
Advances in fine pitch lead free assembly process
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细间距无铅组装工艺的进步
DOI：
10.1109/ectc.2003.1216386
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发表时间：
2003
期刊：
影响因子：
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通讯作者：
R. Tummala
中科院分区：
文献类型：
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作者：
R. Doraiswarni;S. Sankaxwaman;Woopoung Kim;Jing Li;Zhuqing Zhang;P. Gupta;K. Nakanishi;M. Borkar;R. Madhavan;V. Govind;Suna Choi;A. Aggarwal;Yangyang Sun;L. Fan;V. Sundaram;Madhavan Swaminathan;C. Wong;R. Tummala
本研究的重点是发展的最佳标准，选择高电气性能的100微米间距无铅焊料凸点工艺。这是通过对焊盘、工艺、可靠性和测试策略进行建模和仿真来实现的。共面波导（CPW）进行了建模，以发展工艺标准的垫设计和材料的选择。选择聚酰亚胺作为芯片上的钝化层。进一步的信号寄生进行了研究，钝化和选择标准的演变，其厚度。研究了焊盘和钝化层在热循环（空气到空气）下的介电损耗。这种评估导致选择无铅焊料的最佳焊盘配置。通过数值和仿真模型，对焊料的内阻如何影响寄生效应的变化进行了深入的研究。在焊盘上使用标准驼峰下冶金（UBM）。选用无铅焊料（Sn3.5Ag0.3Cu）作为凸点材料。凸点策略的发展，焊料可以沉积在UBM上，而无需模板印刷或电镀。倒装芯片B级光刻也被评估用于晶圆级应用并被标准化。本文最后提出了无铅焊料100 μ m间距倒装芯片应采用的最佳设计、工艺和可靠性标准。伊特罗杜斯蒂乌
This research focuses on evolving the best possible criteria for selecting high electrical performance 100 micron pitch lead free solder bumping process. This is achieved through modeling and simulating the pad, process, reliability and test strategy. Coplanar waveguides (CPW) were modeled to evolve process criteria for pad design and choice of materials. Polyimide was chosen as the passivation on the chip. Further signal parasitics were studied for the passivation and a selection criterion was evolved for its thickness. The pad and the passivation layers were studied for dielectric loss when subjected to thermal cychg (air to ai). This evaluation leads to the selection of the hest pad contigumtion for lead free solder. An in-depth study on how internal resistance of the solder contributes to the change in parasitics is presented through numerical and simulated models. Standard under hump metallurgy (UBM) was used on the pads. Lead free solder (Sn3.5Ag0.3Cu) was chosen as the bumping material. Bumping strategy was evolved by which solder can be deposited on the UBM without stencil printing or electroplating. Flip chip B-stage underfill was also evaluated for wafer level application and standardized. This paper concludes by suggesting the hest design, process and reliability criteria which should be adopted for lead free solder 100 pm pitch flip-chip. Iutroductiou