How are picofarad size capacitors made?

Question

Are they polarized?
What is the chemistry involved?

milli-1000ths
micro-millionths
nano-billionths

pico-trillionths

Answer 1

I would add that modern large value capacitors at lower voltages are also ceramic. Electrolytic capacitors are not desireable for most new designs and should be avoided if possible because they eventually leak. Tantalum is another material that is used in higher value capacitors that is also less than desireable because of its tendency to "flame out" if overvoltaged or reverse biased. Ceramic is the material of choice now for pF values all the way to 10 uF in surface mount packages. For pF values, usually NPO/COG ceramic materials are used to provide better temperature stability and a tighter tolerance in the capacitance value.

Answer 2

Picofarad capacitors are usually made by plating thin insulators with metal films. Common insulators used are mica or ceramic. Glass and plastics are also used, but are less common in the picofarad range. For larger capacitors, multiple layers may be stacked. These capacitors are not polarized.

Medium value capacitors (.0001 to .1) microfarad are usualy made with metal coated plastic films rolled up. These are also not polarized.

Large capacitors (1 microfarad and higher) are usually electrolytic. The insulating film is produced by chemical reaction in an electrolyte. These capacitors are polarized, although non-polarized types exist also.

Answer 3

sorry to answer a question with a question, but the prefix pico- means a trillonth right?