Numerical/Experimental Hybrid Approach to Predict Warpage of Thin Advanced Substrates

A hybrid approach is proposed to enhance warpage predictability of thin advanced substrates. Experimental warpage data of the substrates is first obtained under various conditions. High sensitivity measurements (a contour interval of 6.25 microns/fringe or equivalent to shadow moiré with a grating of 160 lines/mm) "without" painting the surface becomes possible through the advanced shadow moiré method called Shadow Moiré with Non-zero Talbot Distance (SM-NT) in conjunction with the optical/digital fringe multiplication (O/DFM) method. The measured warpage is combined with an FEA approach called trace mapping to incorporate the effect of the copper trace layouts into the analysis. A hybrid model is created through calibration of the properties most critical to warpage, and the warpage values of the substrates at reflow temperature are predicted.