표면실장기술에 있어 설계기준결정에 관한 연구

Determination of Design Criteria Using 3D Solder Joint Configuration in SMT

To provide better understanding of a solder joint design criteria, mathematical models have been developed to calculate the shape of the solder fillets formed between the pad and lead. The effects of parameters such as solder volume and pad dimensions are described with this model. In this study, a systematic way to determine the design criteria of the SMT from the predicted 3D solder joint profile is proposed. The solder joint profile is calculated using the available 3D FEM code which minimizes the system energy due to the surface tension and gravity. The solder joint profiles of gullwing-type lead such as QFP and SOP are calculated for design parameters, and acceptable ranges are obtained. The result shows that the pad length is the most significant factor compared with the pad width and pad area.