THE IMPACT OF INTERFACIAL ADHESION AN PTH AND VIA STRESS STATE

In this paper the impact of the state of barrel-laminate adhesion on t he PTH and via stresses is investigated. A representative PTH and a re presentative blind via in a printed wiring board are used as demonstra tion vehicles. Transient heat conduction and nonlinear elastic-plastic -contact finite element analyses are carried out on PTHs and vias unde r the extreme conditions of perfect and zero barrel-laminate adhesion. In general, the maximum equivalent plastic strains in PTHs and vias w ith strong barrel-laminate adhesion are not large enough to fracture t he plating. Fracture is possible at or near the innerplane junction wh en barrel-laminate adhesion is lost. The possibility of plating fractu re in a blind via is strongly dependent on the tolerances in manufactu ring process parameters such as drill depth and laminate thickness.