Abstract The microstructures, phase transformations and wetting
behaviors of the Sn--Zn--Bi solders were investigated. The
results show that adding 2\%---10\% Bi(mass fraction) to
Sn--9Zn binary alloy, the primary Zn rich phase appears from the
melts firstly on cooling, which results an increase of the pasty
ranges. The crystallizing points decrease with addition of Bi,
indicating a decrease of the melting points. Fixing Bi
concentration, reduction of Zn decreases the pasty ranges, and the
melting points keep stable. Addition of Bi improves the wettabilities,
because the wetting areas on Cu substrates of the
alloys are increased, and the wetting times are shorten.
The diffusion of Zn into Cu at the solder/Cu interface is accelerated
by increaseing Zn concentration, which decreases the
solder/Cu interfacial energy. With addition of Zn, the wetting
areas on Cu substrates of the Sn--Zn--Bi solders increase and the
wetting forces enhance. But the diffusion needs a period of
time, which means a prolonged wetting time. Therefore, Zn
concentration must be controlled in order to obtain a good
matching between the spreading area and the wetting time.
[1]Mulugeta A,Cuna S．Mater Sci Eng,2000;27:95 [2]Katsuki S．Surr Opin Solid State Mater Sci,2001;5:55 [3]McCormack M,Kammlot G W,Chen H S,Jin S．Appl Phys Lett,1994;9:1100 [4] Sung KK,Amit K S．J Electron Mater,1994;8:701 [5]Zhang L,Xian A P,Wang z G,Han E H,Shang J K．Acta Metall Sin,2004;40:1151 (张黎,冼爱平,王中光,韩恩厚,尚建库．金属学报,2004; 40:1151) [6]Shiue R K,Tsay L W,Lin C L,Qn J L．Microelectron Reliab,2003;43:453 [7] Katsuaki S,Toshikazu M,Hiroji N,Yoshitaka T．J Mater Res,2000;4:884 [8]Wu C M L,Yu D Q,Law C M T,Wang L．J Electron Mater,2000;9:921 [9]Kim Y S,Kim K S,Hwang C W,Katsuaki S．J Alloys Compd,2003;352:237 [10]Taguchi,Toshihiko,Katoh,Rikiya,Toyodo,Yoshitaka USP 6503338,2003 [11]Nakatsuka,Tetsuya,Soga,Soga,Tasao,Shimokawa, Hanae,Yamamoto,Kenichi,Harada,Masahide,Ochiai, Yuuji,Kamei,Tsuneaki．USP5942185,1999 [12]Lin W H,Chuang T H．J Mater Eng Perfor,2003;12: 452 [13] Pierre V,Alan P,Okamoto H．Handbook of Ternary Alloy Phase Diagrams．Washington D．C:ASM,1995 [14] Kim H．A Dissertation Submitted for the Degree Doctor of University of California,Los Angeles:UMI Company, 1996:42
