Larger FCBGA package with thin and normal core evaluation and characterization

Abstract

In IC industry, higher electrical performance was always demanded for the application of networking. Therefore, increasing die size, package size and thinner core thickness for networking application were developed to meet the need in recent years. In addition, copper pillar bump is also wildly been used in commercial electrical product to achieve high electrical performance requirement due to lower electrical resistant, thermal resistant and fine pitch benefit. Regarding larger FCBGA package with thin and normal core applications, the potential challenges were included worse package warpage, higher die corner delam risk and poor TIM (thermal interface material) coverage after reflow processes. This paper will aim to investigate larger FCBGA package characteristics with thin and normal core by using Finite Element Method (FEM) to suggest optimal structure and material to reduce failure risk. In this paper, it will investigate the die corner stress (delam risk) and warpage performance from larger FCBGA package with thin and normal core. From the result, it shows larger FCBGA package with thin and normal core would perform worse die corner stress and warpage performance. According to that, underfill selection would be the key point to improve this weak point. Besides that, this paper will also study the heat sink type, heat sink thickness, heat sink footprint width and TIM thickness on TIM coverage, warpage and die corner stress effect. After lots simulation work, this study could provide optimal suggestions for larger FCBGA package with thin and normal core. Besides simulation, some DOE will be conducted to verify the solutions for the assembly of large FCBGA. From the comparison, the simulation results show good alignment with our internal experiment data.