Abstract The study on SOC of article is one of package way for CSP. The SOC transmits messages by Solder Ball joining the board. It can make the volume of product decrease, but the reliability reduces on using. So the reliability of Solder Ball is a very important topic for study. The article for Solder Ball uses the Mixed-Viscoplastic way to simulate the warpage state of SOC when the temperature of Solder Ball rises by ANSYS. Then using the Viscoplastic material parameter simulates the acts by TCT experiment and checks the suitable Fatigue Model to get the analysis results turn into the reliability data. The reliability data puts to the proof with the experimental reliability data and compares differences to other documents.