Comparison of Reliability of Solder Joints by FORM and SORM
The difference in the Coefficient of Thermal Expansion (CTE) between the chip and the substrate generate thermal displacement in the solder joint. It seems to be a main cause of failure in the solder joint when the chip and the substrate are heated repeatedly. The failure of the solder joints by thermal fatigue is known to be influenced by varying boundary conditions such as the difference in CTE, the height of solder, the Distance of the solder joint from the Neutral Point (DNP) and the temperature variation. In this paper, the effects of varying boundary conditions on the failure probability of the solder joint are studied by using the probabilistic approach methods such as the First Order Reliability Method (FORM) and the Second Order Reliability Method (SORM).
Yu Zhou, Shan-Tung Tu and Xishan Xie
O. S. Lee et al., "Comparison of Reliability of Solder Joints by FORM and SORM", Key Engineering Materials, Vols. 353-358, pp. 2593-2596, 2007