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Polyester/Ceramic?

Discussion in 'Electronic Projects Design/Ideas/Reviews' started by hantto, Nov 23, 2002.

  1. hantto

    hantto Member

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    Once again a little question.....

    What's the difference between Polyester and Ceramic Condensators?

    Thx!
     
  2. kinjalgp

    kinjalgp Active Member

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    Polyester caps have polyester dielectric material and ceramics have mica as their dielectric.
    One major diff. is that ceramic has higher leakage current than polyester ones.
    Polyesters are normally used where high precision is required like Hi-Fi Audio Amplifiers etc.
    And cermaic ones are used everywhere :wink:
    Also ceramic are cheap while polyesters are costly.
     
  3. hantto

    hantto Member

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    And once again thanks to kinjalgp! :)
     
  4. dave

    Dave New Member

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  5. pebe

    pebe Member

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    I must correct one point. Ceramics do not have mica as their dielectric. They use fired ceramic (a variety of clay). Mica is a mined raw material and is used as the dielectric in silvered mica capacitors.

    Polyester and polycarbonate have similar characteristics and are used chiefly in capacities from around 10nF to 1uF.

    Silvered mica caps are used for low value tuning caps or similar where high stability is required. They have extremely low Power Factor (low series resistance).

    Ceramic caps in low values (up to 100pF) can be NTO types with just about the same stability as mica types.

    Stabilty is not as good with the larger ceramic caps used as decouplers when small space is a major consideration, because then High K material is often used to increase the capacity. The power factor is olso often higher.

    With those types of capacitors used nowadays, leakage current is not a consideration, because all will have an insulation resistance of at least 1000 Megohms (electrolytics excepted).
     
  6. kinjalgp

    kinjalgp Active Member

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    Thanks for correcting Pebe. :)
     

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