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Illumination & Displays

Optical encapsulant gel for high-brightness LEDs

Dow Corning Corporation's Electronics group has announced the global availability of DOW CORNING® OE-6450, the latest addition to its growing portfolio of optical encapsulants for light-emitting diode (LED) chip sealing and protection. This new two-part formulation, which cures to a flexible gel for use in lens-type LED devices, offers outstanding stress relief, excellent durability, moisture protection, and ultraviolet resistance to maximize light transmittance.

Dow Corning offers a variety of other two-part silicone encapsulants in a wide range of transparency levels, hardnesses and viscosities for different uses and manufacturing processes. Compared with previous offerings, OE-6450 is more resistant to impact because it is softer, with a high penetration value of 45. The new material also provides extremely high light transmittance, with a refractive index of 1.54. Other methyl-type silicone encapsulants on the market today offer significantly less transparency, with refractive indexes of less than 1.42.

Most LEDs are coated with protective encapsulants to prevent electrical and environmental damage, while increasing light output and minimizing heat build-up. Historically, epoxies and other organic materials have been used as encapsulants because of their hardness, transparency and low cost. But inorganic silicone encapsulants are now becoming more widely used as the electronics industry moves toward more powerful, high-brightness LEDs. Silicone encapsulants can withstand higher temperatures than epoxy, and are compatible with lead-free solder reflow manufacturing processes. They also offer high light transmittance and low moisture absorption.