Thermal Properties of Adhesive Systems

Adhesive compounds are uniquely qualified to meet the challenging requirements of assembling die, package, and other components into products able to cope with higher heat loads. Learn why adhesives with ultra low thermal resistance are the preferred bonding compounds for electronic applications requiring superior thermal management.

Conductive bonding agents play a fundamental role in ensuring reliable electrical connectivity in many electromechanical assemblies designed to operate at the extremes of temperature and pressure of space. Failure of a single bond between conductive components in an assembly can ripple rapidly through mechanical and electrical systems, ultimately threatening spacecraft integrity and crew safety. In two applications, Master Bond EP21TDCS-LO conductive epoxy met critical requirements for maintaining robust bonds in electromechanical systems intended to operate in space conditions.

Master Bond EP29LPSPND-3 is a two component, non-drip epoxy compound with a paste consistency that can be used for bonding and sealing applications. The system is electrically non-conductive and thermally insulative, with a thermal conductivity of approximately 0.2 W/(m•K) at room temperature. It withstands cryogenic temperatures and is serviceable in the range from 4K to 250°F. EP29LPSPND-3 features a coefficient of thermal expansion of 45-50 x 10-6 in/in/°C, a tensile strength of 6,000-8,000 psi, and a Shore D hardness of 70-80. This system has a volume resistivity exceeding 1015 ohm-cm at 75°F and a dielectric constant of 4.2 at 60 Hz. A key performance attribute is its ability to withstand temperature cycling even at cryogenic levels. EP29LPSPND-3 has a mix ratio of 100:65 by weight with a long working life after mixing; a 100-gram batch will yield an open time of greater than 5 hours at 75°F. The color of Part A is clear-translucent, and Part B is amber-clear; it cures clear when applied in thin sections despite being a paste, with a refractive index of 1.56 at 589 nm. The recommended cure schedule is either 12-18 hours at 130-150°F or a faster 5-10 hours at 150-165°F. EP29LPSPND-3 is available in ounce jar kits, half pint kits, pint kits, quart kits, and gallon kits.

Master Bond Polymer System EP29LPSP is a two component, high performance, modified low temperature heat cured epoxy system specially formulated for cryogenic applications. EP29LPSP is serviceable at temperatures as low as 4K as an adhesive, sealant and protective coating, but more importantly, it is able to withstand cryogenic shocks (i.e. room temperature down to liquid helium temperatures in a 5-10 minute time period).

Forming reliable bonds between different materials can be challenging because there can be large variations in CTE's (coefficients of thermal expansion). Adhesive compounds play a critical role in the fabrication of assemblies for electronic, optical and mechanical systems. Learn more about typical CTE's for various chemistries such as epoxies and silicones, how fillers can be used to modify CTE, why CTE is dependent on temperature and much more. Specific case studies illustrate the thermal compounds used.

Specially formulated epoxy systems are capable of maintaining performance at temperatures approaching absolute zero, while delivering the required physical, thermal, and electrical characteristics needed for a specific application. Delve into some select case studies to see how specific cryogenic epoxies are used in a variety of high tech industries and applications.