LED Technology
can be a disadvantage too — an additional lens may be needed as the product may not be hard enough to form a lens itself, and as they are soft and susceptible to abrasion. Silicones are UV resistant and tend not to discolour, while offering good temperature resistance of up to 200˚C. We would typically recommend that our customers start by trying Wacker RT 601 or 604. RT 601 is a highly transparent, low viscosity material that offers medium cured hardness, whereas 604, is a softer material.
Silicone potting materials are easy to handle and apply. Cure times are usually long (a day or two). While the curing process can be accelerated with heat, too high a temperature can impact the material’s clarity, and it is a careful balance.
One example comes from our work with a manufacturer of outdoor signage and lighting products. The customer was looking to encapsulate its LED strips to protect them from weather and other external factors, but was experiencing quality issues with the materials they were testing, such as delamination. This was aesthetically unacceptable as it altered the colour temperature of the light output and posed the potential for functional failure. We recommended the customer evaluate
Wacker Silgel 612, which provided good adhesion, optical clarity, and is waterproof. Its gel-like texture means it can absorb shock or vibration, protecting the electronic circuits from damage and thermal cycling.
Processing requirements When specifying a potting compound for an LED assembly, considering the packaging the material will be supplied in can help to build a
straightforward and cost-effective process. For low volume applications, a cartridge or twin-pack might be most suitable, whereas in high-volume applications, bulk containers are typically more efficient. PUs are the most flexible chemistry in terms of the packaging, and they are static mix, which makes them a good option to trial for smaller runs or R&D projects. The materials used for potting LEDs
Pisces Green in the dark - courtesy of SNTech
are typically two-part, meaning they must be both mixed correctly and dispensed accurately. Available process options range from manually mixing and dispensing from a twin-pack, dispensing from a cartridge through a static mixing nozzle, right through to metering, mixing, and dispensing equipment, fed from bulk containers. Epoxies and silicones typically only come in twin-packs and bulk, and many manufacturers find success with a 2-K-DOS metering, mixing, and dispensing system. For applications requiring the highest accuracy, a preeflow eco-DUO precision metering, mixing and dispensing system offers accuracy of ±1%, >99% of the time. This system can be combined with a robot that delivers positional accuracy. Considering the processing requirements early can help to deliver better return on investment. It may be more cost effective to invest in a preliminary technology, and then add to it later. An experienced materials and equipment provider can recommend suitable material and processing equipment for the manual or automatic dispensing of potting compounds.
https://www.intertronics.co.uk/
Innovative HMI concepts As a leading expert in the field of display, touch and embedded
technologies, we offer our customers innovative products, competent advice and individual solutions for the implementation of sophisticated HMI solutions.
› Special shapes, e.g. stretched , curved displays › Pre-configured capacitive & resistive touch sensor technologies › Design and production from prototype to mass production › Extended temperature range › Vibration resistance › Sunlight readability
› PPAP and IMDS entries › Long-term availability › Haptic feedback
LEADING DISPLAY TECHNOLOGY PARTNER
IN-HOUSE OPTICAL BONDING
IN-HOUSE EMBEDDED DEVELOPMENT
IN-HOUSE DESIGN & MANUFACTURING
DATA MODUL Ltd. | Gallan Park, Cannock, Staffordshire WS11 0XG | Phone: +44 1922 45 73 58 |
uk@data-modul.com |
www.data-modul.com
www.cieonline.co.uk. Components in Electronics November 2023 37
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