Some materials that are prohibitively difficult to bond, and chemical adhesives should be cautiously considered due to their inferior bonding capabilities.
Anisotropic conductive adhesives (ACAs) are a group of electrically conductive adhesives that exclusively conduct across the bond-line.
Although silver is expensive it's still the most common conductive epoxy filler. Particles are highly conductive and available in useful shapes and sizes.
Solder outperforms epoxy in regards to electrical resistance, and therefore epoxy is generally only chosen due to specific assembly constraints.
Compares electrical resistance of neat, silver, silver coated glass sphere, nickel, and carbon/ graphite filled epoxy adhesives.
What's the difference between isotropic and anisotropic adhesives? In this post we briefly explore the differences.
Thermally conductive conformal coatings are formulated with metal oxides to provide thermal conductivity without decreasing electrical resistance.
Epoxy resins can be filled with electrically conductive metals to achieve low electrically resistivity and compete with solder in many applications.
Cationic UV epoxy resins can be formulated to cure between opaque substrates. This "dark cure" requires light to activate, but not complete, the reaction.
Cationic epoxies are UV curable, but aren't inhibited by oxygen like free radical alternatives. They do however have their own airborne weakness: moisture.