HYGROTHERMAL ANALYSIS OF HYBRID ELECTRICALLY CONDUCTIVE ADHESIVE AT OPTIMAL MICRO-NANO FILLERS RATIO

Abstract

Recent advancements have significantly advanced hybrid electrically conductive adhesive (HECA) as a pivotal polymer-based interconnector in electronic packaging. However, the durability of these materials remains uncertain, particularly under severe thermal and humid conditions, where current literature provides limited explanation. This paper evaluates the reliability of epoxy-based HECA formulations by varying micro-nano ratios of silver micro-flakes and multiwalled carbon nanotubes (AgMF-MWCNT), ranging from 0.07 to 0.27. The study subjects these formulations to hygrothermal exposure at 85°C and 85% relative humidity over a 3 week ageing period. The evaluation employs gravimetric measurement for water absorption, four-point probe testing for electrical conductivity, lap shear testing for mechanical strength, and scanning electron microscopy (SEM) for morphological analysis. Results show the most favorable ratios are 0.07 and 0.17, which achieve the best electrical and mechanical properties respectively. Upon hygrothermal ageing, anomalous behavior was found in water absorption as weight loss occurs after the first week of ageing. SEM reveals that cracks, delamination, filler pull-out, and filler-matrix debonding were observed on the fractured surface of HECA. In summary, the HECA formulation with a 0.17 ratio demonstrates optimal reliability across all evaluated parameters, underscoring its potential for robust electronic packaging applications.