Abstract
This paper describes the experimental research of the warpage behavior of a thin-core flexible substrate made of multiple layers of metal and polymer components. The composite substrate was subjected to varied temperatures inside a Shadow Moiré chamber and the warpage behavior was carefully measured at different intervals up to the peak temperature. The maximum displacement was carefully monitored using the principle of Shadow Moiré technique which has been used as a non-contact method in obtaining the 3-D shapes and surface morphologies of materials and allows fine tuning of contours to achieve the best resolution. The same measurement procedures were done during its cool down stage. Different surface profiles were created on the substrate which varies depending on the distribution of the metal and polymer components. It also showed that the magnitude of displacement caused by the warpage gradually changes over temperature. By correlating the observed warpage morphologies of the substrate with that of the temperature load, two warpage mechanisms were observed—one that is largely controlled by the thermo-mechanical properties of the individual layers of the substrate creating a saddle shaped warpage behavior and one that is due to the global response of the bulk properties of the substrate with its surrounding materials.
