Mica Capacitor

 
Mica Capacitor

What are mica capacitors? Mica is a group of natural minerals. Silver mica capacitors are capacitors which use mica as the dielectric. There are two types of mica capacitors: clamped mica capacitors and silver mica capacitors. Clamped mica capacitors are now considered obsolete due to their inferior characteristics. Silver mica capacitors are used instead. They are made by sandwiching mica sheets coated with metal on both sides. This assembly is then encased in epoxy in order to protect it from the environment. Mica capacitors are generally used when the design calls for stable, reliable capacitors of relatively small values. They are low-loss capacitors, which allow them to be used at high frequencies, and their value does not change much over time. Mica minerals are very stable electrically, chemically and mechanically. Because of its specific crystalline structure binding, it has a typical layered structure. This makes it possible to manufacture thin sheets in the order of 0.025-0.125 mm. The most commonly used are muscovite and phlogopite mica. The first has better electrical properties, while the second has a higher temperature resistance. Mica is delved in India, Central Africa and South America. The high variation in raw material composition leads to high cost needed for inspection and sorting. Mica doesn’t react with most acids, water, oil and solvents. Mica capacitor definition Silver mica capacitors use mica as the dielectric. They have great high-frequency properties due to low resistive and inductive losses, and are very stable over time. Characteristics Precision and tolerances The minimum tolerance for silver mica capacitor values can be as low as ±1%. This is much better than practically all other types of capacitors. In comparison, certain ceramic capacitors can have tolerances of up to ±20%. Stability Mica capacitors are very stable and very accurate. Their capacitance changes little over [… read more]

Ceramic Capacitor

 
Ceramic Capacitor

What are ceramic capacitors? A ceramic capacitor uses a ceramic material as the dielectric. Ceramics were one of the first materials to be used in the producion of capacitors, as it was a known insulator. Many geometries were used in ceramic capacitors, of which some, like ceramic tubular capacitors and barrier layer capacitors are obsolete today due to their size, parasitic effects or electrical characteristics. The types of ceramic capacitors most often used in modern electronics are the multi-layer ceramic capacitor, otherwise named ceramic multi-layer chip capacitor (MLCC) and the ceramic disc capacitor. MLCCs are the most produced capacitors with a quantity of approximately 1000 billion devices per year. They are made in SMD (surface-mounted) technology and are widely used due to their small size. Ceramic capacitors are usually made with very small capacitance values, typically between 1nF and 1µF, although values up to 100µF are possible. Ceramic capacitors are also very small in size and have a low maximum rated voltage. They are not polarized, which means that they may be safely connected to an AC source. Ceramic capacitors have a great frequency response due to low parasitic effects such as resistance or inductance. Ceramic capacitor definition A ceramic capacitor is a capacitor which uses a ceramic material as the dielectric. The two most common types are multi-layer ceramic capacitors and ceramic disc capacitors. Characteristics Precision and tolerances There are two classes of ceramic capacitors available today: class 1 and class 2. Class 1 ceramic capacitors are used where high stability and low losses are required. They are very accurate and the capacitance value is stable in regard to applied voltage, temperature and frequency. The NP0 series of capacitors has a capacitance thermal stability of  ±0.54% within the total temperature range of -55 to +125 °C. Tolerances of the nominal capacitance [… read more]