在(Cu,Ni)6Sn5發生大規模剝落前銲料體積對其生長的影響

Solder Volume Effect on the Growth of (Cu,Ni)6Sn5 before Its Massive Spalling

王至強(Chih-Chiang Wang)

指導教授 ： 何政恩

元智大學/工程學院/化學工程與材料科學學系/碩士(2012年)

https://doi.org/10.6838/YZU.2012.00034

摘要

隨著環保意識的抬頭，國際間不斷提出對於重金屬使用的禁令。這使得業界一直以來所使用的SnPb銲料，必須改用其它無鉛製程以符合要求。SnAgCu銲料被認為是目前取代SnPb銲料最佳無鉛製程之一。其中，(Cu,Ni)6Sn5自Ni銲墊大規模剝落(massive spalling)，是目前SnAgCu無鉛銲接所遭遇的棘手問題之一。其發生的原因是因為隨著銲接時間的增加，SnAgCu銲料中Cu濃度將隨界面上(Cu,Ni)6Sn5的生長而大幅下降。而因為Cu濃度的改變，將使得界面上原本在熱力學平衡狀態的(Cu,Ni)6Sn5不再穩定，而趨向形成較穩定的(Ni,Cu)3Sn4，於是導致Cu6Sn5以massive spalling的方式重新熔入銲料中。本研究藉由不同體積著手，以製造不同的Cu濃度下降幅度，來探討(Cu,Ni)6Sn5在不同銲料體積下的生長行為，以期能更深入了解觸發spalling的機制。研究發現，經過迴銲後(Cu,Ni)6Sn5皆呈現parabolic的生長模式。然而不同的是，在大銲錫球(銲料直徑dsolder = 760 μm)中所生成的(Cu,Ni)6Sn5晶粒形態係一層連續的針狀結構，而小銲錫球(銲料直徑dsolder = 500 μm)所生成的(Cu,Ni)6Sn5卻是一顆一顆的塊狀結構。有趣的是，dsolder = 500 μm中(Cu,Ni)6Sn5之生長速度卻是dsolder = 760 μm的數倍。研究發現，(Cu,Ni)6Sn5的生長動力學將因其晶粒形態的不同而改變。此種因銲料體積縮小而改變生長動力學的有趣現象，在過去的文獻中很少被提及。有關銲料體積與(Cu,Ni)6Sn5之生長動力學機制，將於本文中作深入的探討。

關鍵字

SnAgCu ； 銲料體積效應 ； 大規模剝落 ； 晶粒形態 ； ripening ； 動力學

並列摘要

Recently, the SnAgCu family alloy has been considered one of the most reliable replacements for SnPb eutectic solder. While many studies have demonstrated that SnAgCu may substitute for SnPb in general joining tasks, recent results have shown that the (Cu,Ni)6Sn5 spalls from Ni substrate is one of the troublesome problems when applying SnAgCu family solder. The concentration of Cu would seriously decrease with the growth of (Cu,Ni)6Sn5, causing a instable situation at the interface and bringing the massive spalling, especially for the solder joints in small volume. The discussion of the (Cu,Ni)6Sn5 growth mechanism between solders with different diameter. In this study, we compared the big solder ball (the diameter dsolder = 760 μm) with the small one (the diameter dsolder = 500 μm) and found out that the growth kinetic of (Cu,Ni)6Sn5 is parabolic in both cases. Although the reaction product was the same at the interface, the growth of (Cu,Ni)6Sn5 was extremely different. First, The morphology of (Cu,Ni)6Sn5 in the case of dsolder = 500 ?m displays as chunk-like instead of needle-like in the dsolder = 760 ?m case. The (Cu,Ni)6Sn5 grew in the case of dsolder = 500 ?m was apparently thicker than that of dsolder = 760 ?m case. The growth kinetics of (Cu,Ni)6Sn5 followed diffusion-controlled mechanism. The change of growth kinectics of (Cu,Ni)6Sn5 due to different solder volume has rarely been reported in the literature. Therefore a detail investigation about the relationship between the solder volume and the growth mechanism of (Cu,Ni)6Sn5 was then provided in this study.

並列關鍵字

massive spalling ； (Cu ； Ni)6Sn5 ； morphology ； ripening ； kinectic ； SnAgCu ； solder volume effect

參考文獻

[陳志銘] 陳志銘，陳信文，柯俊吉，普翰屏，「金層與鎳層對覆晶銲點界面反應之影響」，界面科學會誌，第二十六期，頁119，2004。

[劉櫂陞] 劉櫂陞，「微電子接點之金屬銲墊溶解行為及其交互擴散之研究」，畢業論文，2011。

[BAD] S. Bader, W. Gust and H. Hieber, “Rapid formation of intermetallic compounds interdiffusion in the Cu3Sn and Ni3Sn systems,” Acta Metallur et Materialia, Vol.43, No.1, pp.329-337, 1995.

[GAG] R. A. Gagliano, G. Ghosh, and M. E. Fine, ” Nucleation kinetics of Cu6Sn5 by reaction of molten Tin with a Copper substrate,” Journal of Electronic Materials, Vol.31, pp. 1195-1202, 2002.

[GLA] J. Glazer, “Metallurgy of Low Temperature Pb-free Solders for Electronic Assembly”, International Materials Reviews, Vol.40, No.2, pp.65-93, 1995.