Silicone encapsulants

Silicone as an embedding material has many good advantages. For one thing, silicone has by far the best performance in terms of temperature range. It is flexible and can take up movements (expansion coefficient) that often occur when boards and components rise to working temperature. Silicones wet the surfaces very well, which benefits the heat-conducting properties, and are permeable, which is a big advantage as they do not encapsulate any moisture. With the help of different fillers, a range of desirable properties can be obtained, ranging from relatively hard/tough products (but still flexible) and the whole range down to soft versions in the same class as gels. The range also includes products that provide good heat dissipation, or optical versions with excellent transmission in both the UV and IR range. Silicones for embedding are available both as room temperature-curing or heat-curing. Some types are formulated to provide good adhesion to the substrate, while others require a primer to achieve good adhesion. Silicones are, from a health perspective, the kindest products to use.