表贴电容的分类
表贴电容的分类 Class 1-------------[C0G] –Temperature compensating capacitors: have low levels of barium titanate, calcium titanate, and other things added to increase the dielectric constant, or to get a desired temperature slope. –Very low temperature drift ,aging, voltage coefficient, frequency coefficient, leakage, and dissipation factor. –Dielectric absorption is typically "low" but not usually specified. –Size problem : The voltage breakdown is low ?Class 2-------------[X7R] –Based mostly on barium titanate (Ba2 TiO3 –very poor temperature drift, high voltage-coefficient-of-capacitance and, high voltage-coefficient-of-dissipation factor, high frequency-coefficient-of-capacitance and a significant aging rate {the crystal structure} ?Class 3 –used only for DC blocking and P.S. bypassing, and even then, change in capacitance due to aging, temperature coefficient, and voltage coefficient must be taken into account. –use the lowest K material that you can, and use them at a low percentage of rated voltage. ?Class 4 -------------[Z5U] –the barrier-layer or reduced-titanate ceramics. –low breakdown voltage, high leakage and all-around terrible electrical properties. –obsolete.
