Advanced Co-Planarity Measurement Tools for the Warpage Investigation of Non-Conventional Packages Caused by Reflow and Assembly Process

Two advanced co-planarity measurement systems are presented to investigate the warpage of non-conventional packages subjected to reflow and assembly processes. The systems implement an advanced application of two classical interferometry techniques for deformation measurement. A Twyman-Green interferometry system with sub-micron resolution and designed to accommodate horizontally mounted specimens is used to document real time deformation of assemblies subjected to thermal loading up to solder reflow temperature. A shadow moire system, employing the concept of non-zero Talbot distance to increase dynamic range, improve contrast and increase sensitivity, is used to measure process-induced warpage. Experimental results are shown to illustrate the capabilities of the designed systems.