Cyanate esters adhesives

Cyanate-ester adhesives are produced from resins that contain cyanate groups... 

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-aluminum 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. 

Cyanate ester adhesive Silver QMI301 Loetite 1.9... 

High-modulus adhesives are likely to have high bending stresses, high deflections, and low radii of curvature. As examples, a typical silver-filled epoxy with a deflection of 3 pm had a low radius of curvature of1,070 mm and a cyanate-ester adhesive reported to have a high modulus of 10,000 MPa had a radius of curvature of 5,000 mm. " ... 

Within the last few years, cyanate ester adhesives have started to find applications in the space and, particularly, the satellite market. They are particularly suited to these applications due to their exceptionally low water uptake and out-gassing characteristics, good high-temperature performance and low dielectric constant and low loss tangent electrical properties. 

As carbon/cyanate ester prepregs start to be used in the eonstruetion of antennae reflectors, cyanate ester adhesives will be used to bond the sandwieh panel together. 

Despite all precautions, urethanes can be used most effectively within certain thermal and oxidation limits. Outside these parameters, other adhesives, such as certain epoxies, cyanate esters, and other high-temperature adhesives, should be considered. 

Because of this continued emphasis on adhesive bonding technology development over the years, the airframes of modem front-line aircraft such as the B-2 bomber and the F-117 and F-22 fighters are largely structurally bonded advanced composites. They tend to be comprised of materials that are more advanced (expensive) than commercial aircraft such as carbon and boron fiber reinforcements with cyanate esters, bismaleimides, polyimides or other high-temperature resin matrices and adhesives. 

Addition poly(imide) oligomers are used as matrix resins for high performance composites based on glass-, carbon- and aramide fibers. The world wide market for advanced composites and adhesives was about 70 million in 1990. This amounted to approximately 30-40 million in resin sales. Currently, epoxy resins constitute over 90% of the matrix resin materials in advanced composites. The remaining 10% are unsaturated polyester and vinylester for the low temperature applications and cyanate esters and addition poly(imides) for high temperatures. More recently thermoplastics have become important and materials such as polyimides and poly(arylene ether) are becoming more competitive with addition polyimides. 

Many other modifications to acrylic adhesives are useful. Improved heat resistance of acrylic adhesives can be achieved by incorporating small amounts of epoxy resin into the formulations,77 or by including cyanate esters and organometallic compounds to provide an additional crosslinking mechanism.78 Lower sensitivity of oxygen can be achieved by... 

RTX366. [l one-Poulenc] Supercooled liq. cyanate ester monomer for large aircraft composite structures, micro-wave antennas, radomes, spaceware, and structural or electronic grade adhesives. 

Adhesives are often referred to by their polymer type. The major polymer types used in electronics packaging are epoxies, silicones, acrylics, polyurethanes, polyimides, and cyanate esters. Some generic properties apply to each type but, in generalizing, one must be careful since there are hundreds of formulations of each type on the market, each with minor or major differences in properties. Even for a specific formulation, an adhesive s processing conditions, such as its cure schedule, can affect the final properties. Chapter 3 provides a discussion of the major polymer types and their properties. 

Thermosetting adhesives, on the other hand, soften as the temperature is increased to the glass-transition temperature, but do not melt and resolidify. Instead, because of their highly cross-linked macrostructures, they decompose and char on reaching their decomposition temperatures. Epoxies, cyanate esters, and phenolics are generally thermosetting types. 

A fourth generation of electrically conductive adhesives based on cyanate esters and modified cyclo-olefin thermoset (MCOT) resins was introduced in the 1990s. These resins were specially formulated for low moisture absorption, high thermal stability, and low stress to be compatible with solder-reflow conditions. They were developed to prevent or reduce the so-called popcorn effect, a failure mode attributed... 

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