Some aspects of adhesive-induced corrosion in electronic devices

The corrosivity of adhesives (and other organic materials) used in electronic devices should be a major concern of both the manufacturer of these devices, and the supplier of the materials. This can be dramatized by the fact that almost all room temperature curing epoxy adhesives tested are corrosive. Many of the currently used corrosion and insulation resistance tests can at best yield incomplete information. The non-electrolytic or panel corrosion tests, for example, may provide completely false information for materials to be used as electrical insulators, and the short polarization time of the typical insulation resistance test leaves much to be learned about a material´s long-term service capabilities. The electrolytic test discussed can, in addition to appraising the corrosive attributes of an adhesive, also yield information on degree of cure and the effect of curing environment. This work has suggested a possible factor which influences the long-term durability of adhesive joints, and preliminary studies have indicated the value of further exploration. The importance of humidity to the development of adhesive-induced electrolytic corrosion has been demonstrated. Additionally, the amount of corrosion (or corrosivity of the adhesive) is strongly influenced by the adhesive formulation and cure history, but to a lesser degree by the electrode material, where even the noble metals are subject to corrosion.