Study of New Preconditioning for Solderability Testing

Preconditioning for solderability testing is specified in IEC 60068-2-20 or IEC 60068-2-83 [1]–[2]. However, our previous studies showed that steam ageing treatment and unsaturated PC% treatment specified in the relevant IEC standards may not reproduce the actual warehouse storage [3]. In this study, solderability testing specified in IEC 60068-2-83 was performed on surface mounting device with nickel/tin-plated terminations after each preconditioning (damp heat, dry heat or ambient storage). Tin oxide layer after preconditioning and the cross-section after solderability testing were analyzed by Scanning Transmission Electron Microscope (STEM) with Energy Dispersive X-ray Spectroscopy (EDS) and Scanning Electron Microscope (SEM) with EDS, respectively. The specimen after dry heat indicated different solder wetting behavior and tin oxide layer from that after ambient storage, and that after damp heat indicated solder wetting behavior and tin oxide layer equivalent to that after ambient storage. Damp heat conditioning will be promising as new preconditioning of solderability testing applicable to the actual warehouse storage.