Influence of curing procedures on the electrical properties of epoxy-based isotropic conductive adhesives

Abstract

In this paper, a typical isotropic conductive adhesives (ICAs) composed of an epoxy-based binder containing micro-sized silver flakes was prepared and the effects of different curing procedures on the electrical properties of conductive adhesives were investigated. The results showed that there a greater influence of the curing temperature on 55% silver fill loading, the volume resistivity of ICAs decreased to 4.7×10 -3 from 1.0×10 -3 cured at 180 0 C and 250 0 C, respectively. However, there is almost no effect on the high silver fill loading. The in situ monitoring the variations in electrical resistance of ICAs with 65% silver fill loading was studied during the curing process, and 180 0 C after cured for 27 electrical resistance of ICAs. The reasons for the dependence of bulk resistivity on temperatures were also discussed in terms of the dispersing of the silver flakes in ICAs by SEM.

Real time resistance monitoring during sintering of silver paste

“…Lately, resistance monitoring technology has been applied to study the curing process of epoxybased ICA [11][12][13][14], while such study on SSP sintering process is not found. Inoue et al [11,13,14] found that the change of electrical conductivity can not only be caused by curing reaction of the binder molecules, but also the conductivity change of the inter-filler chemicals, by comparing resistance signals with results from free-damped oscillation method.…”

“…Xiong et al [12] obtained resistance-time curve with ICAs of 65 wt% silver fill loading. The resistance value becomes detectable (< 2.0 MΩ) at 27 min.…”

“…In summary, in previous studies with resistance measurement for ICA curing process, the resistance values are measured at a few (<20) curing times and/or temperatures [5,11,12,[14][15][16][17], M A N U S C R I P T…”

“…and/or monitored with a slow sampling rate [12]. Some studies [3,[11][12][13][14] have missing resistance values because of the range limit of the technology applied. For example in [3], the maximum measurable resistance was 100 MΩ for the method used.…”