Effect of curing conditions on the electrical properties of isotropic conductive adhesives composed of an epoxy‐based binder

Abstract

Purpose

This paper investigates the variations in electrical properties of a typical isotropic conductive adhesive (ICA) made with an epoxy‐based binder that are caused by differences in the curing conditions.

Design/methodology/approach

In‐situ monitoring of the various processes that were used to cure the ICA revealed that electrical conduction in the ICA specimens depends on both the high‐temperature curing conditions and the conditions during cooling to temperatures below the glass transition temperature (T_g).

Findings

The electrical resistivity of the cured ICA specimens after cooling to ambient temperature decreased with increasing degree of conversion, tending towards a convergence value that decreased with increasing curing temperature. The electrical resistivity of the specimens also varied significantly depending on the subsequent annealing process. However, the electrical resistivity achieved after annealing at temperatures above the curing temperatures clearly depended on the particular curing temperature that was used. The characteristics of the polymer structure in the adhesive binder are considered to be different, depending on the curing temperature, and this affects the electrical properties of the ICA;, i.e. the characteristics of the polymer structure obtained during the curing process affect the electrical resistance of the ICA, even after subsequent annealing processes.

Research limitations/implications

This paper discusses generalities of variation in the electrical properties of ICAs during heating and cooling processes. The variation in behaviour in practice will differ depending on the type of adhesive binder in the ICA.

Originality/value

This paper clarifies how the electrical properties of ICAs evolve during the curing, annealing and cooling processes.

Citation

Inoue, M. and Suganuma, K. (2006), "Effect of curing conditions on the electrical properties of isotropic conductive adhesives composed of an epoxy‐based binder", Soldering & Surface Mount Technology, Vol. 18 No. 2, pp. 40-45. https://doi.org/10.1108/09540910610665125