Properties of Cyanate Esters

Product Name/ Description Viscosity (cps) Shelf life (-40°C), Cure Schedule Hardness (Shore A, NASA Outgassing Test Results Lap- Shear Strength (psi) CTE (ppm/°C) ( C) Volume Resistivity (ohm-cm) Thermal Conductivity (W/mK) 

Uralane 7760/ Vantico One-part thermal-transfer adhesive (CTE mismatched parts) 410,000 (RVT, Spindle 14) 3 mos/ 3 hrs 0.5 100°C 70 0.471 % total mass loss (TML), 0.011 collectible volatile condensible materials (CVCM) 200 29 88 -63 2.9 X 10 0.69 

renders cyanate esters highly desirable as die-attach and imderfill adhesives for space applications. 

In spite of their low polarities, cyanate esters adhere well to metal conductors and maintain good adhesion up to 250°C. They are thus compatible with solder-reflow temperatures. The adhesion strengths of toughened cyanate-ester adhesives, as measured from aluminum-to-alumi-num lap-shear specimens are reported to be 5,900 psi at 25°C, 2,572 psi at -67°C, and 4,000 psi at 82°C. 

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The attractive physical, mechanical, and electrical properties of cyanate esters render them the resin of choice in advanced composites for structural and non-structural applications and also in microelectronics. 

Cyanate ester and phenolic triazine (PT). The cyanate ester resins have shown superior dielectric properties and much lower moisture absorption than any other structural resin for composites. The physical properties of cyanate ester resins are compared to those of a representative... 

Table 2.18 Thermomechanical properties of cyanate ester resin ...

Wu S J, Lin T K, Zhang J X and Shyu S S (2000) Properties of cyanate ester-cured epoxy/poly-phenylene oxide blends as a matrix material for Kevlar fiber composites, J Adhes Sci Technol 14 1423-1438. 

Cyanate ester and phenolic triazine (PT). The cyanate ester resins have shown superior dielectric properties and much lower moisture absorption than any other structural resin for composites. The physical properties of cyanate ester resins are compared to those of a representative BMI resin in Table 2.33. The PT resins also possess superior elevated-temperature properties, along with excellent properties at cryogenic temperatures. They are available in several viscosities, ranging from a viscous liquid to powder, which facilitates their use in applications that use liquid resins such as filament winding and transfer molding. 

John, B., C. P. R. Nair, and K. N. Ninan, Effect of nanoclay on the mechanical, dynamic mechanical and thermal properties of cyanate ester syntactic foams. Materials Science and Engineering A, 2010. 527(21-22) 5435-5443. 

Su WFA (1993) Thermoplastic and thermoset main-chain liquid-crystal polymers prepared from biphenyl mesogen. J Polym Sci Polym Chem 31 3251-3256 Su WFA, Chuang CM (2002) Effects of chemical structure changes on curing reactions and thermal properties of cyanate ester-cured rigid-rod epoxy resins. J Appl Polym Sci 85 2419-2422... 

Materials Selection and Chemistry of Cyanate Ester Resins Morphology, Thermal and Dielectric Properties. ... 

Mon Mondragon, I., Solar, L., Nohales, A., Vallo, C. I., Gomez, C. M. Properties and structure of cyanate ester/polysulfone/organoclay nanocomposites. Polymer 47 (2006) 3401-3409. 

CyanatG Ester Curing Agents. Cyanate esters can be used to cure epoxy resins to produce highly cross-linked thermosets with high modulus and excellent thermal, electrical, and chemical resistance properties. They are used in high performance electrical laminate and composite applications. Cure involves oxazoline formation catalyzed by metal carboxylates in addition to homopolymerization of both cyanate ester and epoxy (122). The high costs of cyanate esters however limit their uses. 

Delano (10) studied the use of cyanate esters in carbon fiber prepregs for advanced structural composites. He found that state of the art mechanical properties versus epoxies could be obtained in composites even though the cyanate were not fully crosslinked. Using new catalyst technology (unpublished) we have determined that fully crosslinked systems can be obtained at 170-200 C. These materials have improved thermal, mechanical, electrical, toughness and moisture resistance properties over epoxy resins. 

Both thermoplastic and thermoset resins can be used for ICA formulations. The main thermoplastic resin used for ICA formulations is polyimide resin. An attractive advantage of thermoplastic ICAs is that they are reworkable (e.g., can easily be repaired). A major drawback of thermoplastic ICAs, however, is the degradation of adhesion at high temperature. Another drawback of polyimide-based ICAs is that they generally contain solvents. During heating, voids are formed when the solvent evaporates. Most of commercial ICAs are based on thermosetting resins. Epoxy resins are most commonly used in thermoset ICA formulations because they possess superior balanced properties. Silicones, cyanate esters, and cyanoacrylates are also employed in ICA formulations [48-52]. 

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