Low Stress Adhesives - Features and Applications of Low Stress Adhesives by Master Bond

Epoxies are the most widely used polymeric materials for adhesives, sealants, coatings, pottings and encapsulations and impregnants. They are available in both one and two component systems. Two part systems can be cured at either room temperature or elevated temperature. One part systems must be cured at elevated temperatures (typically 250 - 300°F). One part systems curable by UV light are also available.

Epoxies offer unique versatility in application and performance. Their most desirable properties include high bond strength to a wide variety of different substrates, outstanding gap filling capabilities, excellent electrical insulation, high chemical inertness and outstanding resistance to shock and vibration. Special formulations are available including systems with thermal conductivity (electrically insulating) for heat dissipation, electrically conductive systems, systems for cryogenic applications, as well as systems with high performance in the most hostile environmental conditions. Viscosities and cure times can be tailored to meet specific application requirements.

Silicones are elastomeric systems with the unique combination of flexibility and high temperature resistance. They can be used as adhesives, sealants, coatings and potting materials. Silicone systems are either one or two part. One part systems cure by moisture in the air. Two part systems are cured by the polymerization reaction that occurs when a curing agent is added. Generally, the two part systems can cure in thicker sections than the one part systems.

Aside from temperature resistance and inherent high flexibility, other noteworthy properties of silicones include excellent resistance to water, superb electrical insulation properties and sealing/adhesive properties particularly to glass, plastics, metals and rubber (including silicone rubber itself). Their inherent flexibility allows for “repairability” when this property is needed.

• Sensitive electronic component encapsulation
• MCM (multi chip module) packaging
• Packaging of stress-sensitive semiconductor devices
• To bond circuit assemblies to printed wire boards
• To protect semiconductor packages from cracking under stress
• Through hole and small SMT discrete packages
• Planar waveguides
• To assure stable thermal performance in lid-sealing, underfilling and bonding applications for selected semiconductor packaging applications
• For encapsulation of integrated circuits in a wide range of packaging configurations
• Bonding capacitors to lead frames over a wide temperature range
• For use in asymmetric and surface mount packages exposed to thermal cycling
• Flip chip devices requiring improved crack and fracture resistance
• Ag/Cu and bare Cu lead frame applications in die attach adhesion
• Selected piezoelectric devices
• Integrated optoelectronic devices
• For low stress fiber optic connections
• Fiber optic termination

• Bonding of LED displays, lenses, and other optical components
• To prevent fiber cracking in single and multimode connectors
• Optical fiber fusion splicing compound
• Bonding fiber to glass where low stress epoxy is desirable
• Potting sensors and related devices where thermal cycling is required
• To dissipate stress on electronic assemblies
• To extend a components respective thermal cycling performance
• Mounting devices to flexible circuitry
• Protection of components in constant exposure to thermal cycling
• Bonding of dissimilar substrates with differentiating coefficients of thermal expansion
• High performance valves for micro-battery devices
• Bonding of stress sensitive substrates
• Applications requiring cracking resistance
• Impact & vibration resistance
• Sound dampening
• General purpose thermal cycling
• Piezoelectric & micro machined sensors
• Protection of CSPs from mechanical shock & vibration