In-situ infrared spectroscopy for chemical analysis in electronic packaging processes

Epoxy resins are commonly used for the encapsulation of electronic components in electronic packaging processes. The chemical crosslinking process and therefore the curing of these resins during processing have a significant influence on the production and finally on the quality of the components. To follow the chemical changes during the process, a fourier-transform infrared (FT-IR) sensor was integrated into a molding press to measure in-situ infrared spectra during the process. The feasibility and reproducibility of this measurement method is presented. The spectra generated in the process show changes in absorption bands around 916 cm(-1) and 1230 cm(-1) equivalent to laboratory measurements, indicating the chemical crosslinking process. Several tests show that the repeatability of this measurement method is very good. Further, the influence of different molding temperatures on the generated infrared spectra was investigated, and no significant change in the width, intensity or shift of the bands could be detected. However, the crosslinking of the material is affected by temperature, with low temperatures leading to a slower crosslinking process. With the use of a model, it is possible to estimate the residual enthalpy of the material based on the spectra, which allows subsequent process optimization.