Preparation And Characterization Of Polyimide/Inorganic Composite Films As Solid Dielectrics
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Date
2012-02
Authors
Alias, Asliza
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Abstract
Considerable demand for solid thin-film dielectrics with high dielectric constants for use in the fabrication of capacitors has been observed. In this study, polyimide/inorganic composite films were prepared by incorporating different type of inorganic materials; Al2O3, BaTiO3, TiO2 and ZrO2, into polyimide (PI) derived from PMDA and ODA monomers via ultrasonication method. Chemical structure, morphology, dielectric and thermal properties were investigated by Fourier transform infrared (FTIR) spectroscopy, X-ray diffraction (XRD), scanning electron microscopy (SEM), LCR meter and thermal gravimetric analysis (TGA). FTIR spectra showed complete imidization, and all characteristic peaks of the imide groups are observed in PI/inorganic composite films. XRD diffractogram reveals that the PI/inorganic composite exhibits peaks similar to those of parent inorganic materials, indicating that the crystal structure of inorganic materials remain unchanged and stable after being doped into the PI matrix. SEM micrographs displays a uniform distribution of inorganic particles of Al2O3, BaTiO3 and TiO2 in the PI matrix by means of ultrasonication method and 3-aminopropyltrimethoxysilane coupling agent except for PI/ZrO2 composite. Meanwhile, the dielectric constants and dielectric losses of PI/inorganic composite films generally increase with the addition of inorganic content. The content of inorganic materials does not have significant effect on the degradation temperature of the PI/inorganic composites. Based on the study, PI/BaTiO3 composite is the most potential PI/inorganic composite as solid dielectric as it possesses highest dielectric constant which is 21.1 with 30wt% content at 1MHz and lowest dielectric loss followed by PI/TiO2 and PI/Al2O3. Even though PI/ZrO2 exhibits highest thermal stability, a very high thermal expansion mismatch between PI and ZrO2 induces macro cracks and makes it not suitable as a solid dielectric.
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Electronic industries