Implementing HDI and Embedded Passives In A High-Reliability Aerospace Application

High Density Interconnects (HDI or microvias) have been around for over 20 years, the same is true for buried resistors. The implementation has been focused on small form-factor driven products like mobile phones and cameras. But with the increase use of fine-pitch BGAs (<0.8 mm) components and now, very high I/O BGAs (>2000 pins) with very fast rise-times, military and aerospace applications require the use of HDI as well. The paper also describes the training and phases of implementation, including reliability results and TH-redesign Benchmarks. One of the most useful new tools was a simulation program that was available to assist the designer in the selection of packaging configuration and EP materials. It provided modeling and simulation of interconnections and multilayer stackups for PCB circuit layout with a comparative costing of the density improvements and DFM manufacturability (while design time is reduced) in the use of HDI- microvias/EP over conventional through-hole technology.