For the majority of polyurethanes the minimum operating temperature can be as low as -40☌. Polyurethanes exhibit high UV stability, good low temperature performance, and excellent resistance to a broad range of chemicals. The other disadvantage with epoxy coating is the photodegradation under radiation at high temperatures, which can result in yellowing (due to the formation of thermo-oxidative cross-links). Typical operating temperature is 0 to 60☌. One is that cured epoxy coating is usually brittle owing to rigid cross-linked networks. Epoxy resins are known to have two major shortcomings. It exhibits low shrinkage on cure, good high temperature performance, good acid and alkali resistance. Epoxy resinĪmong these materials epoxy resin is relatively cheap. Resins used for sealing LED strips are generally one of three types, epoxy, polyurethane (PU) and silicone. Before we go any further, attention should also be paid to the sealing/encapsulation materials. To avoid extrinsic failures in environment where high humidity atmospheres or water ingress are likely to be present, it is necessary to seal LED strips to higher IP ratings. Moisture ingress in LED packages can cause a permanent reduction in light output due to delamination between the LED die and the encapsulant. Sulfide-based phosphors are very sensitive to moisture, and they degrade fast under ambient conditions. In LED packages moisture presence in the phosphor layer can affect the rate of chromaticity shift. Moisture absorption from the environment can cause hygroscopic swelling and delamination of the polyimide layers. Flexible circuit boards use layers of polyimides to provide both flexibility and structural integrity for LED strips. Both flexible printed circuit boards and LED packages are vulnerable to water or moisture ingress. Exposure to moisture vapor and ingress of water can significantly shorten the lifespan of LED strips. These LED strips are not intended for use in locations subject to water splashing and jets, condensation of moisture, and saturation with water or other liquids. Moisture-induced failure mechanismsīare LED strips are typically IP20 rated, which means they’re only protected from touch by objects greater than 12 millimeters and is not protected from liquids and moisture. The larger the value of each digit, the greater the protection is. The second digit identifies the level of liquid protection. The first digit indicates protection against solid objects. An IP rating refers to the degree of protection provided by an electronic or electrical enclosure against the intrusion of external dust, fluid, or other objects that may pass through into the product. A waterproof LED strip light is a linear array of LED packages which are assembled on a flexible printed circuit board, with the entire assembly having a minimum ingress protection (IP) rating of IP65.
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