High Glass Transition Dual-Curing Adhesives for Electronics
In the realm of electronics manufacturing, certain processes, such as soldering, reflow, and curing, involve high temperatures. To ensure the durability and reliability of electronic components, it's essential to employ adhesives or potting compounds that can withstand these extreme temperatures without losing their structural integrity. One effective solution is the use of adhesive systems with a high glass transition temperature (Tg), representing the temperature at which a material transitions from a rigid, glassy state to a pliable, rubbery state.
Advantages of High Glass Transition Adhesives
The benefits of employing high Tg materials in electronic manufacturing are substantial. These adhesives offer improved bonding strength at elevated temperatures, reducing the risk of bond failure and providing a safeguard against thermal stresses. This is especially crucial when bonded materials will encounter mechanical stresses or undergo thermal cycling during their lifecycle.
High Tg materials also exhibit reduced creep behavior, ensuring that potted components maintain their original positions and structural integrity over extended periods. Their ability to provide thermal and dimensional stability across a wide operating range contributes to the longevity and improved lifespan of electronic applications.
Moreover, high Tg adhesives tend to possess higher mechanical strength, both at room temperature and elevated temperatures. This added strength serves as a protective shield for potted electronics, safeguarding them against mechanical shocks, vibrations, and various external stresses. Additionally, high Tg adhesives maintain electrical insulation properties and offer resistance to a wide range of chemicals, solvents, and environmental factors.
Products to Consider
Vitralit® UD 8055 and Vitralit® UD 8056 are dual-curing acrylic adhesive systems developed by Panacol, a leading UV adhesives manufacturer. These adhesives primarily cure with UV light but also feature a secondary moisture post-cure mechanism, addressing challenges posed by shadowed areas during bonding. What sets them apart is their remarkable high glass transition range, exceeding 100°C.
These adhesive grades are well-suited for use as encapsulants, providing essential environmental protection for sensors and PCB components. They also excel in bonding dissimilar substrates, including plastics and metals with undercuts or geometry-related cavities, thanks to their dual-cure advantage. The secondary moisture cure mechanism ensures reliable bonding in challenging conditions.
In the primary UV curing process, the bonded areas are fixed rapidly under UV light, with the option to use LED curing systems at wavelengths of 365 or 405nm, offering quick cycle times without warm-up phases. LED and UV pioneer Dr. Hönle offers a broad selection of spot and flood-style systems that are optimally matched to Panacol’s adhesives and can be individually adapted to the application requirements.
The secondary post-curing process allows uncured monomers to crosslink in shadowed areas via atmospheric moisture, enabling high-volume production without subjecting temperature-sensitive electronics to excessive thermal stress.
In applications where encapsulations and bonded substrates must endure prolonged thermal stress, a high glass transition range (Tg) becomes crucial. The Tg exceeding 100°C in Vitralit® UD 8055 and Vitralit® UD 8056 ensures that thermal expansion coefficients behave uniformly, preventing adhesive weakening, excessive stress, delamination, or cracking in electronic components.
These advanced adhesive solutions, particularly designed for sensors, PCBs, and flex PCBs used in consumer and automotive electronics, are ideal for applications with operating temperatures up to 100°C. Their high Tg properties make them the perfect choice for ensuring the reliability and longevity of electronic assemblies in demanding environments.