A two-layer high density printed circuit board and its reliability

The fabrication and reliability of a two-layer high density PCB test vehicl e are reported in this paper. The test board consisted of two copper layers that were sequentially built up on one side of a FR4 substrate and interco nnected through a photovia dielectric layer. Various rest structures were f abricated for reliability testing. Thermal cycling, 85 degrees C/85%RH agei ng, and multiple reflow excursions were performed to test the reliability o f electrical continuity and insulation. Peel strength was measured after fa brication as well as after 150 degrees C annealing and reflow excursions. I nitial results have revealed that photovias may be more reliable than conve ntional through vias. (C) 1999 Elsevier Science Ltd. All rights reserved.