Necking of low-bump-height solder induced by reactive wetting of solder on Au finishes in print circuit board

Author

Chih-Chia Hu ; Khew Woei Haw ; Chun-Yi Wu ; Chih Chen

Author_Institution

Dept. of Mater. Sci. & Eng., Nat. Chiao Tung Univ., Hsinchu, Taiwan

fYear

2013

fDate

22-25 Oct. 2013

Firstpage

136

Lastpage

139

Abstract

We report a necking reliability issue in low-bump-height solder induced by reactive wetting of solder on Au finish in print circuit board. During reflow and solid state aging, the solders diffused to the Au finishes on the print circuit boards and reacted with Au to from Au-Sn compounds. Because the solder volume is very limited, this reaction took a lot of percentage of solders and caused necking of the solder joints. On the other hand, the joints without the Au layers have less necking problem. The necking will have detrimental effect on the mechanical properties of the solder joints. Therefore, it will be a serious reliability issue for flip-chip solder joints with low bump heights and microbumps in 3D IC.

Keywords

flip-chip devices; gold alloys; integrated circuit reliability; printed circuits; reflow soldering; solders; three-dimensional integrated circuits; tin alloys; wetting; 3D IC; AuSn; AuSn compounds; bump heights; flip-chip solder joints; gold; low-bump-height solder; mechanical properties; microbumps; necking reliability; print circuit board; reactive wetting; reflow aging; solder volume; solid state aging; Aging; Gold; Metallization; Nickel; Soldering; Substrates; Tin;

fLanguage

English

Publisher

ieee

Conference_Titel

Microsystems, Packaging, Assembly and Circuits Technology Conference (IMPACT), 2013 8th International

Conference_Location

Taipei

ISSN

2150-5934

Type

conf

DOI

10.1109/IMPACT.2013.6706683

Filename

6706683