An investigation on the bending and curl-forming process of leads in integrated circuit packaging by the finite element method

Abstract

This study provides a simulation model that combines two processing procedures, namely the bending and curling processes, in the forming process of a small outline J-lead (SOJ)-type integrated circuit (IC). The study additionally provides the treatments for the contact between the material and the forming punch, as well as for the contact between the material and the forming die, so as to solve the problem of penetration of the material nodes into the punch and die during the simulated forming process. In this study it is proposed that the algorithm principles of tangent calculation and maximum radial offset are employed to be the basis for adjusting the material nodes which penetrated into the punch or die to the boundary of the punch or die, so as to ensure reasonable deformation of the materials. This study further introduces the concept of strain energy density to predict the possible damage position during the forming process of the lead. From the prediction of the strain energy density, it shows that the possible damage position may occur on the concave point inside the right-angled bending zone of the lead during the bending process. From all the relevant information found, a highly accurate reference value could be established for designing IC-lead forming processes. Moreover, this structural method can also be applied to analyse the processing of other sheet metals that include bending and curling processes.