Thermal reliability of high density interconnects utilizing microvias and standard through‐hole technologies

As high density interconnect (HDI) technologies become accepted in the printed circuit board (PCB) industry, build‐up multilayer (BUM) technologies utilizing laser ablated microvias have grown in popularity. This paper will look at the thermal reliability of the plated blind microvias and through vias using standard thermal shock procedures and interconnect stress testing (IST) methodology. Laser ablated microvias manufactured utilizing unreinforced materials and standard FR‐4 materials will be evaluated, along with colloidal graphite direct metallization and two electroless copper processes. The thermal reliability of these different materials and processes will be determined. This paper is intended to increase BUM usage by increasing the fabricator’s understanding of the processes needed to build metallized microvias and address questions on interconnect reliability by thermal testing.