覆晶無鉛Sn(Cu)/Ni(P)墊層界面反應及其對銲點強度之影響研究

Correlation between Interfacial Reactions and Mechanical Strengths of Sn(Cu)/Ni(P) in Flip Chip Solder Joints

王信介(S. J. Wang) ； 高慧茹(H. J. Kao) ； 劉正毓(C. Y. Liu)

《界面科學會誌》 26卷2期 (2004/06) Pp. 89-98

https://doi.org/10.30020/JCCIS.200406.0003

摘要

本研究探討含銅之無鉛銲料（lead-free solder）與無電鍍鎳磷墊層（electroless-nickel EN）反應中界面反應對於銲點強度之影響。由固態反應結果得知，Ni-Sn化合物生長依循擴散控制程序，其生長活化能為42 KJ/mol。在Sn0.7Cu/Ni(P)的初始固態反應中，界面生成一針狀的Ni-Sn化合物；稍後Cu-Sn化合物於Sn0.7Cu/Ni-Sn界面生成，形成Ni-Sn與Cu-Sn的mixture layer。於Sn3.0Cu/Ni(P)的反應中，Ni(P)表面迅速生成一厚的Cu-Sn化合物，阻止了Ni-Sn化合物的生成而產生一非連續的Cu-Sn/Ni(P)界面。由銲點剪力強度結果顯示固態反應中，Sn0.7Cu界面所生成的mixture layer有較佳的機械強度。相對地，Sn3.0Cu中非連續的Cu-Sn/Ni(P)界面造成較差的機械強度。在液態反應中，由於Ni3P/Cu界面間隙生成，大幅降低pure Sn/Ni(P)銲點強度。而Sn0.7Cu及Sn3.0Cu的系統中，Ni3P結晶層的緩慢生長是由於界面一自生的反應阻障層Cu-Sn化合物。最後得到Sn(Cu)銲點有較佳的機械強度。

關鍵字

無電鍍鎳磷墊層 ； Ni3P結晶層 ； 無鉛銲料 ； 機械強度

並列摘要

The correlation between interfacial reactions and mechanical strengths of Sn(Cu)/Ni(P) solder bumps has been studied. Upon the solid-state aging, a diffusion-controlled process was observed for the interfacial Ni-Sn compound formation of the Sn/Ni(P) reaction couple and the activation energy is calculated to be 42 KJ/mol. For the Sn0.7Cu/Ni(P), in the initial aging, a needle-shape Ni-Sn compound layer formed on Ni(P). Then, it was radually covered by a layer of Cu-Sn compound in the later aging process. Hence, a mixture layer of Ni-Sn and Cu-Sn compounds formed at the interface. For the Sn3.0Cu/Ni(P), a thick Cu-Sn compound layer quickly formed on Ni(P), which retarded the Ni-Sn compound formation and resulted a distinct Cu-Sn compound/Ni(P) interface. The shear test results show that the mixture interface of Sn0.7Cu bumps have fair shear strengths against the aging process. On the contrast, the distinct Cu-Sn/Ni(P) interface of Sn3.0Cu solder bumps is relatively weak and exhibits poor resistance against the aging process. Upon the reflowing process, the gap formation at Ni(P)/Cu interface caused a fast degradation in the interfacial strength for Sn solder bumps. For Sn0.7Cu and Sn3.0Cu solder bumps, Ni3P formation was greatly retarded by the self-formed Cu-Sn compound layer. Therefore, Sn(Cu) solder bumps show better shear strengths over Sn solder bump.

並列關鍵字

Pb-free solder ； Ni(P) ； Mechanical strength