Title :
Materials interaction between inherent barrier Pb-free Sn-Zn-Al solder and Cu contact
Author :
Lin, Kwang-Lung ; Hsu, Hui-Min
Author_Institution :
Dept. of Mater. Sci. & Eng., Nat. Cheng Kung Univ., Tainan, Taiwan
Abstract :
The Pb-free Sn-Zn-Al solder was dip coated on a Cu contact to investigate the interaction between them under aging conditions at 150°C for up to 1000 hours. The results of EPMA analysis indicate that Al gathers at the Cu/solder interface and inhibits the interdiffusion between Cu and Sn. This solder itself provides a diffusion barrier for the Cu contact and thus is termed inherent barrier solder. Cu was found to be able to diffuse to solder under long term heat treatment but not Sn. Nevertheless, Cu was not found to form any compound with Sn in this study. The as-dipped solder reacts with Cu to form an Al4.2Cu3.2Zn0.7 compound. The high temperature heat treatment transforms the compound to Cu5Zn8, Al4Cu9 in a heating duration up to 400 hours. The final product is Cu5Zn8 after 600 hours of aging
Keywords :
ageing; aluminium alloys; assembling; chemical interdiffusion; copper; diffusion barriers; electrical contacts; electron probe analysis; environmental factors; flip-chip devices; heat treatment; integrated circuit interconnections; integrated circuit packaging; interface structure; reflow soldering; tin alloys; zinc alloys; 1000 hr; 150 C; 400 hr; 600 hr; Al interdiffusion inhibitor; Al4.2Cu3.2Zn0.7; Al4.2Cu3.2Zn0.7 compound; Al4Cu9; Cu contact; Cu diffusion; Cu/solder interface; Cu5Zn8; EPMA analysis; Pb-free Sn-Zn-Al solder; SnZnAl-Cu; as-dipped solder-Cu reaction; diffusion barrier; dip coating; final Cu5Zn8 product; flip chip solder bump; heat treatment; heating duration; high temperature heat treatment; inherent barrier Pb-free Sn-Zn-Al solder; inherent barrier solder; materials interaction; Aging; Electrodes; Flip chip; Heat treatment; Intermetallic; Nickel; Solids; Temperature; Tin; X-ray scattering;
Conference_Titel :
Electronic Materials and Packaging, 2000. (EMAP 2000). International Symposium on
Conference_Location :
Hong Kong
Print_ISBN :
0-7803-6654-9
DOI :
10.1109/EMAP.2000.904183
