TWI Frequently asked questions
Electrically conductive adhesives (ECAs) consist of a dispersion of metallic particles (such as iron, copper, gold, gold coated polymer spheres and silver) in a polymer resin (such as epoxy, silicone, thermoplastics etc). ECAs canbe either Isotropic (ICA) or Anisotropic (ACA) in nature.
ECAs rely on touching contact between metallic particles and the device/substrate surfaces. ICAs are electrically conductive in all directions due to their high loading with silver (typically 25-30 vol%), while ACAs are conductivein one direction only (generally in the direction of applied pressure), and are often known as z-axis adhesives. Metal content in ACAs is typically 5-20 vol%.
Conductive adhesives can be used in any application where electrical conductivity is required. Low cost ICAs, filled with copper or nickel, have been used to bond earth straps to various components, preventing build-up of staticelectricity. Increasingly, ICAs are being considered as possible replacements for lead-solders in surface mount and electronic applications. ACAs have been used to attach liquid crystal displays in various applications, and inflip-chip assemblies.
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