Technical Glossary Optical Clear Adhesive (OCA)

[Optical Clear Adhesive (OCA)]

Optical clear adhesive (OCA) began as a product made by 3M, but as it became more widely known, OCA has come to refer to any adhesive material with a high light transmittance. OCAs have been polymerized (molded) and can be converted into sheets. OCAs have several advantages over OCRs, which are liquids. For example, OCAs are easier to handle, their thickness is easier to adjust, bonding equipment is relatively low cost, and the bonding process time is usually shorter.
On the other hand, OCRs are superior to OCAs, because OCAs have to be die-cut, which causes apparent materials costs to be comparatively high. OCAs also do not accommodate black print gaps and are prone to delayed bubble formation if contamination is present. There are UV-cure OCAs, which improve black print gap filling and reworkability. These are bonded in a half-cured state, and are fully cured after bonding with UV light.
There are currently acrylic-, polyurethane-, and silicone-based OCAs on the market. Relatively thin products of thicknesses between 25 to 250 µm are most popular, but recently OCAs up to 2 mm thick have become available.