Electromigration and Thermomigration in Ball Grid ArraySn-Zn-Ag-Al-Ga Lead-Free Solders

• Main Authors: Ger-Pin Lin, 林哲平
• Other Authors: K. L. Lin
• Format: Others
• Language: zh-TW
• Published: 2006
• Online Access: http://ndltd.ncl.edu.tw/handle/46125153766103878900

碩士 === 國立成功大學 === 材料科學及工程學系碩博士班 === 94 === Eutectic Sn-Pb solder are mainly used to connect the electronic devices and printed circuit board. But, many countries have concerned about lead, which would pollute environment and hurt human health. The development of lead-free solders has become the most important issue, oxidation resistance, wettability, and other properties. This study investigated Sn8.5Zn0.5Ag0.01Al0.1Ga solder balls, which was developed by our lab. This study investigated the micro-structure of solder balls under electromigration and thermomigration effects. After assembly, we would apply different of current density to solder balls at 120℃. Electrons would impact the intermetallic compounds (AuZn3 and AgZn3) seriously in current crowding section. The intermetallic compounds would decompose. The atoms coming from intermetallic compound decomposition would move in the direction of temperature gradient and react to form intermetallic compounds. Without other atom to occupy the site in which intermetallic compounds decomposed, it would be observed voids. If the directions of thermomigration and electromigration were the same, Sn atom would be affected seriously by temperature gradient and electric impaction, and move in the direction. In this lead-free solder, the AgZn3-AuZn3-AgZn3 three layers compound would transfer and consume the Zn-rich phase in solder balls.