A study of the polymerization of novel cyanate ester/acrylate blends

Chemistries for High Reliability in Electronics Assemblies

This article provides a review of the attitude of the scientific community towards reliability in electronic packages, with emphasis on the prevailing mechanisms for package failure under highly stressed environmental conditioning. Once this failure mechanism is fully developed, approaches to the resolution can be more rigorously applied. Overall, the predominant evidence points to moisture, both diffusivity and equilibrium weight gain, as the key factor in reduced reliability performance. Other fundamental polymer properties are important, but generally, methods are well established for adjusting these parameters. Moisture uptake is somewhat inherent to a particular chemistry type and this can direct the use of resin systems that are more suited to particularly moist environments. Epoxy resin systems, while pervasive in the electronics industry, do have limitations under humid environmental test conditions. Cyanate ester resin chemistry is claimed to have low moisture uptake by virtue of a non-hydrophilic cure mechanism. However, certain aspects of the cure chemistry and side reactions with water can result in misleading predictions on humid environment performance. Siloxane-based materials present an attractive solution to many moisture related issues. Traditional condensation and addition cure silicone systems have, thus, found widespread use as packaging adhesives and encapsulants. Siloxane-functional polyimides have also been successfully utilized in a number of application areas. Relatively new siloxane/hydrocarbon resins, developed specifically for electronics applications, further address the shortcomings of classic silicone adhesives and coatings.

Effect of monomer chemical structures on the cell structures and properties of cyanate ester foams

Cyanate ester (CE) foams with different chemical structures were prepared using bisphenol A dicyanate ester (BADCy), bisphenol E dicyanate ester (BECy), and tetramethyl bisphenol F dicyanate ester (TBFDCy) as monomers, through a two-step process. Rheological tests were performed to investigate the optimal conditions for the preparation of these foams. The results of morphology by scanning electron microscopy showed that cells are in the form of nearly spherical shape in foams from TBFDCy and BADCy and oval in foam from BECy. The thermal properties of the three CE foams were studied by methods of dynamic mechanical analysis (DMA), differential scanning calorimetry (DSC), and thermogravimetry/differential thermogravimetry analysis. The glass transition temperature ( Tg) obtained from DMA tests are 274, 264, and 241°C for the foams from TBFDCy, BADCy, and BECy, respectively, which are apparently higher than that tested by DSC method. The Tg, compressive properties, and thermal stabilities of the foams are improved after the introduction of the alkyl-substituent groups to the same aromatic ring of –OCN functionality, and the chemical structure–properties relationships are explained according to the monomer chemical structures.

Thermal Conductivity Cyanate Ester Resin Composites Filled with Boron Nitride

Boron nitride (BN) powder was modified by silane coupling agent, and a series of cyanate ester resin composites containing the modified BN were prepared. The effect of volume fraction of BN on the thermal conductivity, electrical insulation properties of these composites was investigated. Results show that addition of a little of BN powder can improve thermal conductivity of the composites effectively, while the composites still retain the relatively good electrical insulation and low dielectric constant. When the volume fraction of BN was 23.6%, the thermal conductivity of composite increased to 1.33 W/(m·K), which is 4.6 times that of pure resin.