Title :
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
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;
Conference_Titel :
Microsystems, Packaging, Assembly and Circuits Technology Conference (IMPACT), 2013 8th International
Conference_Location :
Taipei
DOI :
10.1109/IMPACT.2013.6706683