Design and reliability assessment of stacked fan-out packaging

Fan-out solution is developed vigorous in advance assembly field, major solutions are two ways, one is wafer level, and other is panel level method. In this research, we plan to use glass as substrate and do wafer level fan-out structure design; the advantages of the glass substrate are smoothness, flatness, CTE adjustability, low power consumption, low dielectric constant, and ultra-high resistance of the glass substrate. We will explore different design factors with finite element model (FEM) coupled with the Coffin-Mason equation is used for life prediction in simulation models. Based on these design and investigation, we could come out design factors to enhance fan-out glass package property and we also manufacture real test vehicle to do OBTCT and verify the simulation investigation. The goal of this research is to design wafer-level package structure with the fan-out features, with the domestic manufacturers to develop the glass substrate design to complete wafer-level stack packaging technology development design and life performance. The preliminary study will be carried out for the stacking unit design finite element simulation analysis and with the appropriate test products to provide experimental data, by changing the package body geometry, material and other design parameters to understand the parameters on the reliability of the stacking unit. The preliminary study will be carried out for the stacking unit design finite element simulation analysis and investigate the critical point to cause failure, discuss package design factors and mesh size to come out stable simulation results, then comparing and checking the strain and estimate life time by thermal cycle loading. To define factors this could enhance fan-out structure with glass substrate. For this fan-put package with glass substrate, stress buffer layer and dummy ball is related to life cycle. The study of stress buffer layer related to life cycle result and ball matrix design are showed in figure 3. The final life cycle calculate by Coffin-Manson equation can varies from about 780 to 1218 while changing the SBL thickness from 5 to 20um. If add dummy ball design, we could increase 20% above performance. We found factors to enhance the reliability characteristic behavior of packaging on the thermal cycling test.