The homogeneous electrochemical oxidations of four phenothiazine derivatives, three isomers of benzophenothiazine and triphenodithiazine, were studied in acetonitrile solution together with phenothiazine itself. Their first and second redox potentials were determined by means of cyclic voltammetry. In all the materials examined, reversible one-electron oxidations were characterized. The electrogenerated cation radicals, except for triphenodithiazine, underwent a second one-electron oxidation and, after a subsequent chemical transformation, formed the corresponding benzophenothiazinium cations. For triphenodithiazine, only the first oxidation potential was observable under our experimental conditions. The electronic states of both the intermediates and the final products of electrolytic oxidation were identified by their electronic absorption spectra and electron spin resonance absorption spectra. The values of the first oxidation potential of the benzophenothiazines were proportional to the ionization energies, which were given by molecular orbital calculations.
Silicone resins are widely used for electronic packaging as potting and encapsulating materials. Silicone resins have many advantages for electronic packaging applications such as superior electrical properties, thermal stability, low water absorption, etc. Furthermore, silicone resins are not only used as protective materials for integrated circuit (IC) devices but also as conducting materials for interconnection. However, silicone resins have two big drawbacks: low adhesion strength and low molecular weight creep. A simple liquid-liquid extraction method has been developed to purify silicone resins, which will improve adhesion strength and eliminate low molecular weight creep. This paper describes the results of the liquid-liquid extraction method to remove low molecular weight cyclic siloxanes. Fourier transform-infrared (FT-IR) spectroscopy was used to monitor the removal rate of low molecular weight cyclic siloxanes. Thermogravimetric analysis (TGA) was used to evaluate the purity of silicone resin. Gas chromatography-mass spectrometry (GC/MS) was used to identify the low molecular weight cyclic siloxanes. Thermomechanical analyzer (TMA), dynamic mechanical analyzer (DMA), and die shear test were used for evaluate the properties of silicone resin.
Silicone resins are widely used for electronic packaging as potting and encapsulating materials. Silicone resins have many advantages for electronic packaging applications such as superior electrical properties, thermal stability, low water absorption, etc. Silicone resins are not only used as protective materials for IC devices but also as conducting materials for interconnection. However, silicone resins have two big drawbacks: low adhesion strength and low molecular weight creep. A simple liquid-liquid extraction method has been developed to punfy silicone resins, which will improve adhesion strength and eliminate low molecular weight creep. This paper describes the results of the liquid-liquid extraction method to remove low molecular weight cyclic siloxanes. Fourier Transform-Infrared (FT-IR) spectroscopy was used to monitor the removal rate of low molecular weight cyclic siloxanes. Thermogravimetric analysis (TGA) was used to evaluate the purity of silicone resin. Gas chromatography-mass spectrometry (GC-MS) was used to identlfy the low molecular weight cyclic siloxanes. 10. Kazunari Suzuki, Tomoko Higashino, Kunihiro Tsubosaki, Akira Kabashima, Katsutoshi Mine, Kazumi Nakayoshi, ('Development of low elastic modulus die attach material and clean cure process", Bm. of 40th IEEE Elec. Components and &hology G.zz&rence, p. 835-839, (1990).
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