Thermally conductive and electrically insulative epoxy for medical devices

Master Bond EP40TCMed is a two-part, room-temperature curing epoxy system that meets the requirements of ISO 10993-5 for non-cytotoxicity. It is thermally conductive, electrically non-conductive and can be used as an adhesive or sealant in various medical and wearable applications.

This toughened epoxy provides an elongation of 60-70%. It has good strength properties with a tensile lap shear strength between 2,300 and 2,500psi, a T-peel strength of 40-60pli and a low tensile modulus of 5,000-15,000psi at room temperature, making it excellent for applications where low stress is required. The system’s small particle size filler permits effective heat transfer when applied in thin layers, reducing its thermal resistance. It can also withstand exposure to EtO, radiation and several sterilants, and anti-microbial cleaning agents. Serviceable from -100F to +300F (-73C to +149C), it provides reliable electrical insulation characteristics with a dielectric constant of 4.4 at 60Hz and a volume resistivity greater than 1015-Ohm-cm. Its thermal conductivity is 8-11 BTU•in/(ft2•hr•F) [1.16-1.60 W/(m•K)].

The epoxy system offers convenient handling with a 1:1 mix ratio by weight and has a relatively long working life of 2-3 hours for a 100g batch of mixed epoxy at 75F. After mixing, the epoxy has a moderate viscosity of 80,000-100,000cps, which is beneficial for applications where some, but not too much flow is needed. Upon cure, it has low shrinkage and a hardness of 70-80 Shore D. It is provided in standard-sized units of ounce jars, half-pint, pint, quart, and gallon kits. It is also obtainable in premixed and frozen syringes.