Medtech distributor launches new UV-curable epoxies for dam and fill processes

John P Kummer, a supplier of high-performance speciality adhesives, announces the launch of its new Ultraviolet (UV)-curable epoxies for dam and fill processes in the medical industry within the United Kingdom.

The “dam & fill” process with two materials is mainly used in cases where a component needs to be protected with either an optically-transparent or opaque encapsulant. The process can also be used if a conventional glob-top material is too viscous to flow underneath and around fine wires. Due to the low viscosity of optically transparent encapsulants, a dam is applied around the component first to prevent the potting material from flowing over the substrate.

Epo-Tek OG116-31 is a UV-curable epoxy which has a thixotropic nature. Thixotropy refers to certain gels and materials that under static conditions are thick but when agitated can begin to flow. After a period of time, thixotropic materials will return to their initial more viscous state. 

Epo-Tek OG116-31 can be cured very quickly with UV-light. Afterwards the encapsulant, which could be either another UV-cure or a thermoset material can be applied. Whilst OG142-87 is typically used for a UV fill, both products have a high glass transition temperature (Tg >100°C).

Like most UV-cure epoxies, both OG116-31 and OG142-87 are cationic products, and ionic polymerisation is initiated by photo-generated ions. The cure process continues until all polymers are consumed. Generally, cationic products have the benefits of less shrinkage and higher adhesion over free radical cured systems and are not adversely impacted by an oxygen rich curing environment.

Rob Church, sales manager, JP Kummer said: “The dam and fill process is often a tricky operation. However, these two new UV-curable epoxies make it more straight-forward, with more consistent applications. We are really pleased to make these available.”