This article is part of The engineer’s complete guide to capacitors. If you’re unsure of what type of capacitor is best for your circuit, read How to choose the right capacitor for any application.
What is a paper capacitor?
Paper capacitors use paper as their dielectric. These are non-polarized capacitors that are often selected for high voltage and high current applications. They are used in power systems as coupling, decoupling and bypass capacitors and as energy reservoirs in automotive audio power amplifiers.
For an explanation of these terms, read: The engineer’s capacitor glossary: All terms and acronyms defined.
Operation of paper capacitors
Paper capacitors have two conductive plates separated by a paper dielectric. These electronic components are typically impregnated with wax or oil to eliminate air spaces between the cellulose fibers. Some are rated to operate 50,000 hours, which at 24/7 operation equates to about 5.7 years.
Capacitance values for paper capacitors range from about 0.001 µF to 10 µF, and maximum voltage ratings are less than 2000 V. These capacitors are susceptible to moisture, which can reduce their breakdown voltage. Metalized paper capacitors are available.
Applications of paper capacitors
Paper capacitor technology is considered vintage. Old radios and vacuum tube guitar amplifiers often used paper capacitors.
Alternatives to paper capacitors
Newer technology metal film capacitors or ceramic capacitors are superior alternatives to paper capacitors.