Fabrication, Mechanical and Dielectric Characterization of 3D Orthogonal Woven Basalt Reinforced Thermoplastic Polyimide Composites
The 3D orthogonal woven basalt fiber reinforced polyimide (PI) composites were fabricated and characterized in this study. The PI film was firstly prepared to determine PI processing parameters. Fourier transform infrared (FTIR) analysis showed that 300°C was the suitable imidization temperature. Thermal gravimetric analysis (TGA) and differential scanning calorimetry (DSC) results showed relatively good thermal properties of the PI film. In the fabrication of composites, the multi-step impregnation method was applied. The bending properties of 3 mm-thick composite showed increasing trend in all and the second-time impregnated composite had much higher value than the first-time impregnated composite. Moreover, the bending fracture mode photos showed obvious creases except for the first-time impregnated materials, which agreed well with the bending property values. The dielectric constants for the composites were complex because they had not regular value following the mixing rule of the composites, which was mainly due to the interfacial polarization and other effects in the fabrication processing.
Preparation and Properties of Glass Cloth-reinforced Meltable Thermoplastic Polyimide Composites for Microelectronic Packaging Substrates
Meltable thermoplastic polyimide resins (MTPI) with designed polymer backbones and controlled molecular weights for advanced microelectronic packaging substrate application have been synthesized by thermal polycondensation of aromatic dianhydride and aromatic diamine in presence of endcapping agent. The thermoplastic polyimide resins could be dissolved in organic solvents to give low viscosity solutions, which were then employed to impregnate E-glass cloth (EG) to yield MTPI/EG prepregs. After removal of the organic volatile, the MTPI/EG prepregs were plied up and then melt processed to give MTPI/EG composite laminates with high quality. Experimental results demonstrated that the MTPI/EG composite laminates showed desirable characteristics, including: (1) excellent thermal stability; (2) good mechanical properties; (3) great electrical insulating and dielectric properties; as well as (4) high peel strength between copper foil and the composite surface.
The uniform treatment of carbon fiber surface in three-directional orthogonal fabric by oxygen-plasma
An oxygen-plasma treatment of carbon fibre surface in three-directional orthogonal fabric preforms was investigated in this paper. The effects of this treatment on the surface wettability and chemical components of the fibres in both the interior and surface regions of the fabrics were analyzed by using dynamic capillary method and X-ray photoelectron spectroscopy (XPS), respectively. A microdebonding method was employed to determine the uniformity of interfacial shear strength between the fibre and matrix in different regions of the carbon fabric-phenolic composites, and the flexural strength was also tested to evaluate the effects of the treatment. The results indicated that, the oxygen-plasma significantly improved the interfacial adhesion by etching, activating the surface of the fibres, and generating the oxygenic functional groups. However, for the fibres in different regions of the fabric, the degrees of the treatment were different, and a longer treatment time was needed to get the relative uniform effect through the fabric. Meanwhile, the loss of tensile property of the fibre due to treatment was investigated and found to be small in the range of useful treatments.