Eutectic Solder Bonding for Highly Manufacturable Microelectromechanical Systems Probe Card

• Published in: Japanese Journal of Applied Physics 2011-06, Vol.50 (6), p.06GM18-06GM18-5
• Main Author: Kim, Bonghwan
• Format: Article
• Language: English
• ISSN: 0021-4922; 1347-4065
• DOI: 10.1143/JJAP.50.06GM18

We developed eutectic solder bonding for the microelectromechanical systems (MEMS) probe card. We tested various eutectic solder materials, such as Sn, AgSn, and AuSn, and investigated the bonding ability of Sn-based multi-element alloys and their resistance to chemical solutions. The Sn-based alloys were formed by sputtering, electroplating, and the use of solder paste. According to our experimental results, Sn-rich solders, such as Ag 3.5 Sn, Ag 3.5 Sn 96 Cu 0.5 , and Sn, were severely damaged by silicon wet etchant such as potassium hydroxide (KOH) and tetramethylammonium hydroxide (TMAH). On the other hand Au 80 Sn 20 was resistant to those chemicals. In order to verify the joint bondability of the solders, we used a cantilever probe beam, and bump which were made of nickel and nickel alloy. After flip-chip bonding of the cantilever beam and the bump with Au 80 Sn 20 solder paste, we measured the contact force to verify the mechanical strength. We then re-inspected it with X-rays and found no voids in the joint.