Selective Laser Modification for Stress Mitigation and Warpage Reduction in Advanced 3DIC and Optoelectronic Packaging

Selective laser scanning enables spatially localized tuning of polyimide (PI) thermo‑mechanical properties to mitigate thermally induced stress and warpage in advancedd 3DIC and optoelectronic packaging, without changing the global material selection. Laser‑processed PI films are characterized and the resulting property changes are incorporated into a 2D plane‑strain finite‑element model. The representative coupon/model has an in‑plane span of 10 mm and a total thickness of 50 μm (47 μm Si with 3 μm PI). Local modification is applied only in 1 mm corner patches to target high‑stress regions, while the remaining PI remains pristine. Using a minimal‑constraint (free‑warpage) boundary condition and mesh‑objective evaluation metrics (warpage and near‑corner area‑averaged stress), the localized modification reduces warpage and mitigates stress concentration; solder fatigue trends are assessed via inelastic strain‑energy density per cycle (Darveaux).