Papers by Keyword: Voids Formation

Abstract: This paper presents the method to estimate curing profile's parameters for curing process of Moisture Resistance Cyanate Ester (MRCE) based underfill used in Flip Chip Ceramic Ball Grid Array (FC-CBGA). The two steps curing profile was found to eliminate voids formation in underfill during curing process. The important parameters in two steps curing profile such as first fixed temperature and duration of second temperature rise were estimated by superimposed of cure initiation curve and weight percentage loss curve of underfill epoxy material. Differential Scanning Calorimeter (DSC) analysis was carried out to characterize the cure kinetics reaction of underfill epoxy and produced the cure initiation curve. Thermal Gravimetric Analysis (TGA) was performed to characterize the weight loss of underfill and produced the weight loss curve. It was estimated that the first fixed temperature and duration of second temperature rise for two steps curing profile were 100 oC and 60-80 minutes respectively. The simulation experiment was conducted to verify the profile and no voids formation observed along this curing process.

Abstract: Underfilling is the preferred process to reduce the impact of the thermal stress that results from the mismatch in the coefficient of thermal expansion (CTE) between the silicon chip and the substrate in Flip Chip Packaging. Voids formation in underfill is considered as failure in flip chip manufacturing process. Voids formation possibly caused by several factors such as poor soldering and flux residue during die attach process, voids entrapment due moisture contamination, dispense pattern process and setting up the curing process. This paper presents the optimization of two steps curing profile in order to reduce voids formation in underfill for Hi-CTE Flip Chip Ceramic Ball Grid Array Package (FC-CBGA). A C-Mode Scanning Aqoustic Microscopy (C-SAM) was used to scan the total count of voids after curing process. Statistic analysis was conducted to analyze the suitable curing profile in order to minimize or eliminate the voids formation. It was shown that the two steps curing profile provided solution for void elimination.