Thermal Cycling Resistant Adhesives

Master Bond offers a wide variety of epoxies, silicones, polyurethanes, polysulfides and UV curable formulations designed to withstand thermal cycling. These compounds are also ideal for the bonding, sealing, coating and potting/encapsulating of substrates exhibiting different coefficients of thermal expansion and contraction. Durable and tough, these products exhibit outstanding performance in high and low temperature environments.

Applications Featuring Thermal Cycling Resistant Polymer Systems

Some common applications using Master Bond’s thermal cycling epoxies and silicones include:

• Sealing heat exchanger tubes and endplates
• Encapsulation of heat generating devices and modules
• Bonding metal and fiber reinforced composites in aerospace production
• Packaging of stress sensitive semiconductor devices

Key factors that need to be carefully evaluated in selecting the proper formulation include the temperature exposures, speed of temperature change, frequency of cycling, time spent at each extreme (long/short dwell times at different temperatures), types of substrates being joined, thickness, width, length of bond, joint geometry. One and two component compositions have been developed to closely match the thermal expansion coefficients of the substrates being joined through the incorporation of specialized fillers. Flexibilized resilient compounds in comparison absorb the thermally induced stresses between widely divergent substrates. This extends adhesive longevity, improves device reliability, prevents embrittlement/crack propagation, debonding from thermal cycling. Blends of epoxy resins containing elastic resins that minimize loss of T_g, extremely soft silicones, toughened UV cure products with rapid cure speeds have proven successful in many thermal cycling applications. Most noteworthy has been the use of high elongation epoxy polysulfide hybrid compositions to optimize cycling capability especially in low temperature environments.