Cyanate ester based resin systems for snap-cure applications

摘要

Resin compositions comprising cyanate ester have been demonstrated to be useful as die attach adhesives, underfills and encapsulants, where the characteristics of the resins can be varied in a wide range by copolymerization with functionalized comonomers such as epoxies, phenols, rubbers, thermoplastics and others. To reach a combination of properties such as long pot life, short cure time and high glass transition temperature, we encapsulated small particles of effective hardeners to make them insoluble and non-reactive when mixed with the resin at room temperature. Pot lifes of more than 3 months could be reached, whereas the same cyanate ester gels and becomes solid within 30 mm at room temperature, if the neat hardener is used instead of the capsules. At a certain elevated temperature, which mainly depends on the structure of the hardener, the capsules open and the curing reaction starts immediately. Low-temperature systems with cure times less than 5 mm at 80 ℃ reach glass temperatures of about 140 ℃, and a glass transition temperature of 220 ℃ after 10 s cure can be achieved with another combination. The developed snap cure resin systems can be easily mixed with a lot of common additives such as minerals, tougheners, metallic powders and others to cover a wide range of performance characteristics for use as adhesives, underfills, encapsulants and the like.