Cyanate ester resin based composites with high toughness and thermal conductivity

Abstract

A new cyanate ester resin-based composite with higher toughness and thermal conductivity was developed. First, a poly(n-butyl acrylate)/poly(methyl methacrylate-co-acrylamide) (PBMAM) core-shell structured latex was prepared by seeded emulsion polymerization. Second, hexagonal boron nitride (h-BN) particles were modified by a surface coupling agent, 3-(2-amino ethyl amino)propyl trioxysilane, to improve the dispersion in cyanate ester resin (BADCy). Third, PBMAM and the modified boron nitride were mixed with BADCy resin to increase mechanical properties and thermal conductivity. The monomer conversion in the emulsion polymerization process of the PBMAM was monitored by determining the solid content. Its particle size was characterized by dynamic laser scattering, and the morphology of the particles was characterized using scanning and transmission electron microscopes. The modified boron nitride (ABN) was verified by FTIR and TGA measurements. The mechanical properties and thermal conductivity of the BADCy/PBMAM/ABN composites were determined at various BN contents. Results showed that the unnotched impact strength of the composite increased by 151% and the thermal conductivity increased by 85% at a PBMAM content of 5 wt% and ABN content of 6 wt%. With the enhanced properties and ease of fabrication, the developed composites have good potential for application in high-end industries such as microelectronic packaging.

Fig. 1. Preparation procedure of PBMAM.

Fig. 2. Modification procedure of h-BN.

Fig. 3. Variation with reaction time of (a) measured and theoretical z-average particle diameter, d_z; (b) particle diameter distribution of the final latex; (c) instantaneous and overall conversion.

Fig. 4. PBMAM latex (a) TEM core–shell structure, (b) SEM particle distribution.

Fig. 5. FTIR spectra of h-BN and ABN.

Fig. 6. XRD patterns of (a) h-BN, (b) ABN.

Fig. 7. TGA curves of h-BN and ABN.

Fig. 8. Mechanical properties of BADCy/PBMAM/BN composites as a function of filler contents. (a) Unnotched impact strength; (b) flexural strength.

Fig. 9. SEM images of fractured surfaces of BADCy and BADCy/PBMAM/ABN composites with different ABN contents: (a) BADCy; (b) 2 wt%, (c) 4 wt%; (d) 6 wt%; (e) 8 wt%; (f) boron element mapping with ABN addition of 6 wt%.

Fig. 10. Thermal conductivity of the cyanate ester composites as a function of boron nitride content.

Fig. 11. Resistivity of the cyanate ester composites as a function of boron nitride content.