Finite element analysis on reliability of soldered joint of J-lead

Finite element method was used to simulate the soldered joint of J-lead of the SOJ (Small Outline J-lead Package). Results indicate that the distortion is obvious, the ceramic carrier with up-warp trend, the J-lead with forth extension trend, but the PCB with little distortion because of the rigidity displacement restrict. The strain of the J-lead soldered joint' soldered heel is bigger than the soldered toe and the center place has the least strain. The stress of the J-lead soldered heel is bigger than the other place of the soldered joint and the stress distributes a wide area, where is the weakest place of the whole soldered joint, so it is easy to lose efficacy. The stress of the J-lead soldered toe is less than the soldered heel, and the stress distributing area is small. On the contrary, the J-lead soldered joint' center place distributes a large area and the stress value is one order less than the stress value of soldered heel and soldered toe, so it is the safety place of the soldered joint. The calculated values are in agreement with the experimental results.