Investigation of Micro-Raman Spectroscopy to Determine the Degree of Cure for Tiny Dot Epoxy Adhesive

Abstract

Epoxy adhesive has been widely used in microelectronic production process and the technique to determine the degree of tiny dot adhesive cure is essential to evaluate the products. In this work, micro Raman spectra were demonstrated to examine the adhesive curing at small diameter of about hundred micrometers. There are two Raman peaks that can be observed then modification during the curing process while it is bond to observe the change in the infrared absorption due to the background absorption. These two Raman peaks located at 1260 and 790 cm-1 due to C-C breathing and C-O-C epoxide ring vibrating, respectively. It is found that the relative peak heights decrease as a function of UV exposure time. The vibration of Raman peak for heat cure were investigated for comparison the bond vibration of epoxy was also study by DFT in term of vibration rotation analysis for both close and open epoxy ring models which used to describe the vibration before and after curing processes. The open epoxide ring model shows the reducing of epoxide peak. Relative Raman peak heights are proposed to be used for determining the degree of adhesive cure. With imaging ability of micro Raman system, the mapping of curing sample can be illustrated by setting the color map with the proposed relative Raman peak height.