Marked Reliability Increase of Plastic-Cored Solder Ball for Large Size Wafer-Level CSPAuthors: Hiroya Ishida and Kiyoto Matsushita
Company: Sekisui Chemical Co., LTD, Japan
Date Published: 11/5/2012 Conference: IWLPC (Wafer-Level Packaging)
In this study, we focused on the composition of PCSB in order to maximize its reliability properties and obtain greater reliability in larger-sized WLCSP that use fine ball pitch. We evaluated various compositions of PCSB and compared the reliability performance with conventional solder ball technology. The advanced type of PCSB achieved over 1000 temperature cycles in WLCSP with a package size of 10.2×10.2 mm square, and a ball pitch of 0.3-mm in a temperature range of -40 deg. C. to 125 deg. C. According to the observation of cross sections after TCT, the major crack of the advanced PCSB occurred along the copper electrode, while one occurring using conventional PCSB occurred along its copper layer. SEM analysis revealed that the intermetallic compound (IMC) was formed in the interfaces of the copper layer and the electrode. The IMC of the advanced PCSB was (CuxNiy)6Sn5 and fine in form, whereas the IMC of conventional PCSB was Cu6Sn5 and rough in form. This results in the advanced PCSB demonstrating better TC life.
This technique contributes to excellent reliability and underfill-resin-less in WLCSP, and proves that advanced PCSB is capable of large-size packaging design applications.
WLP, CSP, Reliability, Solder Ball
Members download articles for free:
Not a member yet?
What else do you get when you join SMTA? Read about all of the benefits that go along with membership.
Notice: Sharing of articles is restricted to just your immediate work group. Downloaded papers should not be stored on an external network or shared on the internet.