Capacitors Blog

There are many types of mica, but only six or so are common rock-forming minerals. Mica capacitors are normally made from muscovite mica, or potassium aluminum silicate, KAl₂Si₃O₁₀(OH)₂ . It is thermally stable up to 500°C, and has a high dielectric strength. Phlogopite mica, or potassium magnesium silicate, KMg₃Si₃AlO₁₀(OH)₂ , is softer than muscovite mica and has less desirable electrical characteristics, but

it may be used up to 900°C. Mica deposits are found in Madagascar, Central Africa, South America, and India. India is probably the biggest supplier of mica.

For meeting more and more customer's requirement on the urgent delivery, recently Suntan made an important decision that we will keep stock for some series, starting from tantalum capacitor which is always with long lead time, as well as hot offer TS08S X2 capacitors.

From the year of 2010, with the order increased sharply, our production lines are always overload and the delivery schedule is longer than former accordingly. Our management realized the importance and emergency of the availability of stocks, and decided to keep stock for some common series. The lead time of tantalum capacitor are extremely long, and the current requirement from the market for our TS08S X2 capacitor is fairly well, as a result we chose these 2 series as a starting. If you need these 2 series, just feel free to check with Suntan professional sales if any stock available or not. With the support from customers, we believe our stock could cover a wider range of series in the near future!

Shortcut to specs:
Tantalum capacitor - radial ---> http://www.suntan.com.hk/pdf/Tantalum-Capacitors/TS19.pdf
Tantalum capacitor - SMD ---> http://www.suntan.com.hk/pdf/Tantalum-Capacitors/TS20.pdf
X2 capacitor ---> http://www.suntan.com.hk/pdf/Plastic-Film-Capacitors/TS08S.pdf

These capacitors use Mica for the dielectric. Mica capacitors have good stability because their temperature coefficient is small. Because their frequency characteristic is excellent, they are used for resonance circuits, and high frequency filters. Also, they have good insulation, and so can be utilized in high voltage circuits. It was often used for vacuum tube style radio transmitters, etc.
Mica capacitors do not have high values of capacitance, and they can be relatively expensive.

Suntan Dipped Mica Capacitors are designed to meet the exacting physical, electrical and environmental requirements of the MIL-C-5 and RS-153 specifications.

It is well known that natural mica is extremely stable against heat. Silvered mica is made by printing electrodes on mica film with special silver paste. The silvered films are stacked to the desired value interleaved with metal foils for contact. Then the terminals are clamped on to the element. (The terminals are copper clad steel wires finished with a solider coating for good solder ability). The clamped unit is either dipped under vacuum in epoxy resin and coated with epoxy powder conformably or dipped in phenolic resin and vacuum impregnated with liquid epoxy resin. The envelope thus formed gives high moisture and heat resistance to the unit. This design ensures high reliability and stability.

Careful selection of raw materials and constant monitoring of all equipment and processes provides an overall uniform level of quality consistent with the stringent requirements of today's most sophisticated electronic equipment.

Silver mica capacitors, also known as silvered mica capacitors, rendered traditional mica capacitors obsolete. Instead of being clamped with foils these use sheets of mica coated on both sides with deposited metal. The assembly is dipped in epoxy. The advantages are:

1.greater stability, since there are no capacitive airgaps that can change dimension

2.airtight enclosure removes the risk of oxidation or corrosion of plates or connections.

3.greater capacitance per volume, since

• there are no airgaps between plates and mica,
• the conducting surfaces can be thinner.
• no clamping mechanism is needed

Mica Capacitor Specifications：

Capacitance Range : 1pf – 22,000pf
Tolerance : ±0.5pf, ±1%, ±2%, ±5% ~ 20%
Rated Voltage : dc 50v, 100v, 300v, 500v
Operating Temperature: -55℃ ~ 125℃
Withstanding Voltage: rated voltage x 2 (vdc) within 1-5 seconds

Link：http://www.suntan.com.hk/pdf/Mica-Capacitors/TS23.pdf
Contact Email：info@capacitors.com.hk

Natural mica contains many other materials including, iron, sodium, ferric oxide, and lithium. Because of the variability in composition of natural mica, mica destined for use in capacitors must be carefully inspected and classified, which adds to the manufacturing cost. All varieties of mica are chemically very stable and inert. Mica does not react with oil, water, most acids, (the exceptions are hydro-fluoric and sulfuric acid) alkalis, and solvents.

Mica’s thermal, electrical, and chemical properties make for excellent capacitors. Capacitance change with temperature range from ± 500 ppm/°C to 50 ppm/°C, depending on the construction technique. Mica capacitors exhibit very little voltage dependence, with dC/dV less than 0.1%. Mica capacitors have high Q or conversely small power factors (range 0.0001–0.0004) that are quite independent of frequency. This, combined with low inductance designs, result in capacitors that are ideal for high frequency and RF applications. Specification sheets of mica capacitors commonly show parameters plotted into the gigahertz range.

There are many types of mica, but only six or so are common rock-forming minerals. Mica capacitors are normally made from muscovite mica, or potassium aluminum silicate, KAl₂Si₃O₁₀(OH)₂ . It is thermally stable up to 500°C, and has a high dielectric strength. Phlogopite mica, or potassium magnesium silicate, KMg₃Si₃AlO₁₀(OH)₂ , is softer than muscovite mica and has less desirable electrical characteristics, but it may be used up to 900°C. Mica deposits are found in Madagascar, Central Africa, South America, and India. India is probably the biggest supplier of mica.

Mica, a mineral, is one of the oldest dielectric materials used in capacitor construction. There are several kinds of mica, with differing properties, but mica is in general very stable electrically, mechanically, and chemically. It has a dielectric constant in the range 5–7. Mica has the interesting property that its crystalline structure is asymmetrical. The binding forces in one plane are quite strong, while the binding forces along the perpendicular plane are very weak. Because of this, it has a distinct layered structure, and it is possible to split or cleave mica into very thin, optically flat, sheets. For capacitors, mica sheets in the range 0.025–0.125 mm or even thinner are used.