Warpage studies of HDI test vehicles during various thermal profiling

New techniques and technologies involved in the miniaturization of printed wiring board (PWB) fabrication are rapidly emerging. The quality, performance, and reliability of surface mount assemblies built on these next-generation boards will depend on many factors, including thermally induced warpage. Therefore, quantitative warpage measurement is critical in new PWB assembly design evaluation, and determining overall thermal performance characteristics. Using an automated infrared reflow oven simulation system, the warpage of six bare high density interconnect (HDI) samples is measured under two different heating profiles. Out-of-plane surface displacement is measured with a non-contact shadow moire technique and resolution enhancement method called phase-stepping. The two types of samples evaluated were built for the purpose of warpage study, where physical data could be used to validate finite element analysis (FEA) results. The warpage results obtained with the two thermal profiles will be presented.