Light curable adhesives for wearable consumer electronics

To address the growing consumer wearable electronics market, adhesives supplier Intertronics has introduced the Dymax 9200-W Series of next generation light curable encapsulants and structural and optical-positioning adhesives.

The range is made with low-sensitising ingredients for products that are touching, or near, the skin such as smartwatches, fitness trackers, VR headsets or goggles, earbuds, and headphones, as well as for applications where devices cannot be hermetically sealed. The materials cure in seconds on exposure to UV and/or visible light, which allows greater throughput and reduced processing costs.

The Dymax 9200-W Series has been developed without isobornyl acrylate (IBOA), a common skin irritant, which reduces concerns around skin sensitivity in consumer wearable electronic devices. During the assembly of such products, the materials are suitable for optical and lens positioning, assembly bonding and sealing, electronics encapsulation, wire and flex tacking, and structural bonding.

The four products in the series are suited to different parts of the assembly process, and can be used individually, or in combination, for a total solution. Though not designed for direct skin contact, they are suitable for products that are worn on the body for short- or long-term periods, where extractable or leachable materials might be a concern.

Dymax 9200-W Series materials enable high bond strength and excellent moisture resistance to enhance the reliability of devices. Alongside the technical benefits, there are process advantages, too. The series of adhesives and encapsulants are made of 100% solids to ensure no solvents are released during application and curing. This also eliminates the need for solvent handling, while enhancing worker safety and minimising environmental impact. In addition, the materials cure “on demand” in seconds on exposure to the correct wavelength of light. Manufacturers can also opt for one of the two formulations, with secondary moisture cure that aids the curing of shadow areas.

“Globally, there has been a remarkable increase in consumer demand for smartwatches, headphones, hearing aids, AR/VR glasses, and other consumer electronics products in the last few years,” said Ben Swanson, chief commercial officer at Intertronics. “These new materials incorporate all the technical and process benefits of light curable materials to the consumer wearables market, while being designed specifically with skin sensitivity in mind. This brings manufacturers confidence that their products will be safe, reliable, and long-lasting for consumers.”

The series includes four grades. Dymax 9201-W, a high viscosity light and moisture cure encapsulant, offers a secondary moisture cure for applications with shadowed areas such as chip on board, chip on flex, or wire bonding. It is recommended for surfaces including FR4 and Polyimide. Dymax 9202-W is a low-shrinkage material designed for optical alignment and lens positioning applications where low to minimum movement is required, such as lens positioning. It is suitable for applications with full light access or minimal light shadow, when bonding glass, metals, ceramics, FR4, and PC. 

Dymax 9210-W is a high viscosity moisture cure encapsulant designed for the selective protection of components from chemical or environmental exposures. It is both LED and broad spectrum curable, optimised for 405 nm. Finally, Dymax 9211-W is designed for camera module assembly and is low shrinkage, low stress, and curable with both broad spectrum and LED lamps. It is recommended for bonding a wide range of substrates including ABS, FR4, LCP, PA6, PC, PET, PETG, PI, PU, and TPU.

To support the building of a productive adhesives or encapsulant process, Intertronics supplies complementary equipment for dispensing and UV/LED light curing systems.