The Impact of Interfacial Adhesion on PTH and Via Stress State

Abstract

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