Thermomechanical and Viscoelastic Properties of Dielectric Materials Used in Fan-Out Wafer-Level Packaging

The fan-out wafer-level packaging (FOWLP) has gained significant interests owing to the cost effectiveness, high performance, high I/O density, high integration capability, small form factor and diverse range of applications. FOWLP is currently seen as the best fit for the highly demanding mobile and wireless market, and is attractive for other markets focusing on high performance and small size. However, up to date, wafer warpage is still one of the unresolved challenges in this field. As an integral component of the electronic packaging, dielectric materials could also contribute to the overall warpage. Nonetheless, this contribution is sometimes excluded from the theoretical warpage calculation. Even when the dielectric material was included in the finite element modeling, the simulation results have not been able to duplicate the actual experimental results yet. The difference between the modeling and the experimental results could be due to the only incorporation of elastic properties of the polymer dielectric materials in the simulation, instead of the viscoelastic behavior. Here, we reported the thermomechanical, and viscoelastic properties of three commercial dielectric materials that have been used in the FOWLP and construct master curves via the time-temperature superposition principle to study the relaxation behaviors of the dielectric materials. These results could support the ongoing development of an accurate modeling system for prediction and control of wafer warpage in the FOWLP.