Optics and packaging are playing an ever more important role when designing LED-based products which are both efficient and maintain performance over long periods of time. Silicone elastomers have proven themselves to be versatile in solving a variety of design and production issues. Our sales partner, ACC Silicones, have published a guide to products and applications in this growing field.
These include Optically Clear Encapsulants, a range of gels with differing cure cycles and physical properties. Together with harder silicone elastomers we can offer a product for most LED potting applications which require optical clarity. In particular, we can offer refractive index from 1.40 to 1.49, with an exciting new product available at 1.53.
Dissipating unwanted heat away from the diode to a suitable heat sink is essential for overall performance and can easily be achieved by selecting a thermally conductive silicone encapsulant. When selecting a thermally conductive encapsulant there is always a trade off between flexibility and thermal conductivity, due to the nature of the fillers used – as you raise the conductivity you will also see a rise in hardness. ACC Q-Sil 553 has been proven to provide a good balance offering reasonable conductivity whilst retaining a low modulus and hardness, thus reducing stress during the thermal cycle.