LED potting problem resolved in less than 24 hours

Louise Davis

The Indian LED lighting systems specialist, Rockforest Technologies India Pvt Ltd, was recently contracted to supply LED strip lighting units for luminaires destined for a shopping complex in Bangalore, India.

The specification stipulated that Rockforest’s LED lighting strips should provide a ‘neutral white’ (4,000K) colour and that the LEDs in the luminaires be potted to protect them from adverse environmental conditions

Electrolube India conducted some trials, potting the strip luminaires to a specified depth of 5.5mm using Electrolube’s UR5634, a semi-rigid, optically clear polyurethane resin widely used for encapsulating LED lighting systems.

With excellent protective and decorative properties, the UR5634 resin is also highly UV resistant.

In this particular application the resin caused a colour shift from the LED array, from the specified 4,000K (neutral white) to ‘cool white’ (6,500K).

Rockforest was under considerable pressure to solve this problem as the 4,000K colour was a non-negotiable specification. Moreover, their customer requested that a new reference sample, which met the 4,000K colour specification, be made available for re-testing in just 24 hours.

Electrolube’s technical support team needed to act quickly to help Rockforest meet this very tight deadline and suggested two different approaches.

The first of these was a recommendation that they use an LED that provided a colour temperature below the specified colour temperature - in this case, one operating in the 2,500K to the 3,000K range.

By potting these with the UR5634 resin to the specified 5.5mm depth, it potentially could bring the light back to the desired colour.

The second option was that Rockforest assesses the amount and type of resin they were using for this project to see if a thinner layer of resin over the top of the LED array would reduce the colour shift effect.

Ultimately, following further discussions with Electrolube, Rockforest opted to use UR5635, Electrolube’s semi-rigid polyurethane resin, formulated with a ‘hazy/cloudy’ appearance, suitable for dispersing light.

The diffused light produced by this resin meant that an additional diffuser medium was no longer necessary, allowing the customer to achieve the required aesthetic appearance and, through trials with various resin potting depths, the correct colour temperature.

During these trials, the rapid gel time of UR5635 caused a complication but Electrolube solved this problem by suggesting a staged potting procedure.

Electrolube’s UR5635 exhibits outstanding water and weather resistance, as well as excellent resistance to acids and alkalis making it suitable for a wide range of environments and an extremely durable potting compound.

It is also resistant to UV light, making it especially useful as an outdoor LED encapsulant or for use in other applications where it may be exposed to direct sunlight.