Quality Assessment

Due to the unique configuration of DIP package leads having a flat shouldered structure, extra care must be exercised in hole size design and insertion. Too large a hole diameter which results in the shoulder contacting the edge of the PTH, combined with too high an insertion force, could result in fracture of the copper plated layer at this point. Even at normal insertion forces, the localised pressure exerted at the small contact area is increased considerably and could result in failure of the plating. Creating a fissure, or discontinuity of any kind in the plated layer, leaves a path open for laminate degassing during the soldering operation. The result of the degassing is a poorly formed solder joint with voids and blowholes present, the source of which is not clearly evident to the board manufacturer unless careful metallographic work is carried out. Unless precise orientation of the samples and accurate control of polishing is carried out, the source of the problem might very easily be missed when examining the microsections.