Effects of humidity, ionic contaminations and temperature on the degradation of silicone-based sealing materials used in microelectronics

This paper investigates the effects of three ageing factors (chemical, humidity, and temperature) and their interactions on the physical properties and degradation of silicone sealant used in microelectronic applications. The thermal degradation of silicone sealants was investigated by exposing samples to temperatures in the range of 150 up to 175 °C. Also, a set of samples were aged at 40 °C in a salt spray set-up with 100 % humidity in a salty atmosphere. Results showed detectable changes in the FTIR spectra of aged specimen as compared with the as-received sample. In all accelerated testing conditions, peak intensities decreased with ageing time, inferring that that the surface characteristics of the sealant is affected by ageing. Shear test results showed that with increasing the ageing time, the maximum shear stress in most cases has decreased in all ageing conditions. Also, it appears that samples with longer ageing times have experienced more elongation before failure. Results also show that salt spraying of specimens is associated with a decrease in the mechanical properties of the sealant, indicating the deleterious implications of ionic contaminations for the mechanical properties of samples. The design of the experiment was used to investigate the effects of three ageing factors and investigate their interactions on the physical properties of silicone rubber used in a particular industrial process. • In all accelerated testing conditions, peak intensities decreases with ageing time. It is an indication that the surface characteristics of the sealant is affected by thermal ageing and oxidized. • In the shear and tensile test it is shown that with increasing the ageing time, the maximum strength stress in all cases decreases at all ageing temperatures. • One of the observations in the mechanical test is that shear and tensile strength of 1 % Al2O3 mixture have best strength among all the conditions, and alkali environment has shown the decreasing trend of ageing. • Results showed that nanoparticles with 3 % Al2O3 have negative impact on the sealant as they adversely influence the flowability/viscosity of the composite mixture.