Characterization of wafer level package for mobile phone application

Hyundai Electronics has developed the wafer level chip size package, named Omega CSP, to provide the right package solution for mobile electronics products that require light weight, small size and low cost. The aim of this paper is to report both the electrical characteristics and the reliability of Omega CSP that has been used to assemble static random access memory (SRAM) device for cellular phone application. When compared to the current major package format, i.e., μBGA, Omega CSP showed the similar electrical AC/DC characteristics. To certify package level reliability, temperature cycling (TC) test and pressure cooker test (PCT) were carried out. There was no crack or delamination after reliability test. In the temperature cycling test (-55°C to 125°C) at board level, Omega CSP with 325 μm or 425 μm solder ball pad passed 1000 cycles. In addition to temperature cycling test, mechanical shock test, variable frequency vibration test and four point twisting test at board level were also evaluated. Considering the lower cost as well as the smaller form factor of real chip size than current package, Omega CSP has a high potential to be applied into mobile electronics product