How to choose LED light bar potting material?

Update:06 Sep 2021
Summary: With the popularity of LED light strips and the increase in...
With the popularity of LED light strips and the increase in market capacity, choosing a suitable potting glue for LED flexible light strips has become one of the most headaches for many LED light strip manufacturers. If you choose the right potting compound, you will “make a profit”. It is reported that there are currently three types of potting glues: epoxy resin potting glue, polyurethane potting glue and silicone potting glue.
Among them, although the epoxy resin potting glue has better light transmittance and better stacking effect, it can make the cured LED flexible light bar look bright and round. However, it can only be used within -50C to 550C, and the toughness tends to become poor at high temperatures. In many cases, when the temperature exceeds 600C, the soft light bar glue will soften, causing the colloid to easily break; at the same time, when the temperature is lower than -50C , The colloid becomes hard and brittle, and the light bar shakes slightly, the colloid peeling and embrittlement will occur; after the lamp bead is lit for 400-700 hours for a long time, the epoxy resin above the lamp bead becomes yellowish brown, causing the light The brightness decreases and the color temperature changes.
The light transmittance of the polyurethane encapsulant is between 85-92%, and the cured light bar has good flexibility. After curing, the gel can be used for a long time between -250C and 950C; but the hardness of the polyurethane gel cannot be achieved. Very low, the product can only be applied to epoxy-type or semi-sleeve-type flexible light strips. As the temperature decreases, the flexibility of the light bar changes greatly; when potting, the FPC surface and environmental humidity are required to be higher. If the humidity is too high, the product surface is prone to white fog and insufficient adhesion; When used outdoors for a long time, the colloid will usually turn yellow in 2-3 years.
Silicone potting glue is currently the most popular potting glue on the market. After curing, the hardness of the colloid can be adjusted. It can be used as a jelly gel or a harder shoreA 30 degree glue, so silicone The potting glue can be used for drip-type light bars, semi-tube type light bars, and full-tube light bars. After curing, the glue can be used between -450C and 2000C, and with With temperature changes, the mechanical and physical properties and optical properties of the product will not change significantly. It is very suitable for use in severe cold regions such as Russia, Northern Europe, and North America. In addition, the silicone potting glue has good resistance to ozone, ultraviolet rays, acid and alkali, and can keep it from yellowing for a long time in outdoor use; but the adhesion of silicone potting glue to FPC is lower than that of epoxy and piles up. Slightly inferior blemishes.
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