Whats the best material to make the plates in a capacitor - Page 1
Forum section: electronics / projects

author: electronics technician
author_rank: Regular Contributor
timestamp: March 28, 2014, 03:40:54 pm
content: i need advice on what materials will make the best capacitor platesany input is welcome thanks

author: nanofrog
author_rank: Super Contributor
timestamp: March 28, 2014, 05:03:24 pm
content: Aluminum (cheap, widely available, particularly for large values)Tantalum (more expensive than aluminum, but better frequency and temp stability)Silver (i.e. silver mica capacitors; more expensive yet, but have higher precision, are stable, and reliable for the values available)Other Metals, such as brass (think variable air capacitor)

author: electronics technician
author_rank: Regular Contributor
timestamp: March 28, 2014, 05:09:56 pm
content: nice aluminum foil is what i shall use i have lots of it

author: JackOfVA
author_rank: Unknown
timestamp: March 28, 2014, 10:29:05 pm
content: For an air variable capacitor, silver plated copper is about as good as you can get without extraordinary expense. Fuzed Pyrex glass and Teflon for insulation material, etc. Incredibly expensive and not something you will find off the shelf.

author: dannyf
author_rank: Super Contributor
timestamp: March 28, 2014, 10:29:56 pm
content: QuoteNothing (=vaccum) is the best.

author: Marco
author_rank: Super Contributor
timestamp: March 28, 2014, 11:15:09 pm
content: Quote from: JackOfVA on March 28, 2014, 10:29:05 pmRolls of mylar (or alternative high quality brands of BOPET) occasionally show up on ebay.BOPP packing film can also be found quite easily (it's the slightly rigid/crinkly stuff they generally use to wrap flowers) although I have no idea if the dielectric quality of that compares in any way to the BOPP used in commercial capacitors (when the quality it has good it has similar dielectric strength as mylar but less loss).

author: JackOfVA
author_rank: Unknown
timestamp: March 28, 2014, 11:24:49 pm
content: Can't make "plates" from vacuum or mylar for that matter.Dielectric, yes, but the original question was about plate material.

author: Macbeth
author_rank: Super Contributor
timestamp: March 29, 2014, 12:10:35 am
content: I remember tearing capacitors apart as a child in the 70's (and trying to launch old dead valves as "rockets") and the caps all used aluminium foil rolls and some kind of grease. Only the variable caps used solid metal plates.I never tore a cap apart later on, but certainly have had my fair share of exploding electrolytics!

author: han
author_rank: Frequent Contributor
timestamp: March 29, 2014, 12:38:41 am
content: coated copper?since it will decrease the ESR

author: Conrad Hoffman
author_rank: Super Contributor
timestamp: March 29, 2014, 11:50:47 am
content: What kind of capacitor? For tuning caps in the old days, brass was considered superior to aluminum for reasons of temperature drift. The really stable caps in one of my cap bridges are made of Invar, enclosed in dry nitrogen. OTOH, in an aluminum electrolytic, the best plates seem to be made of aluminum.

author: CaptnYellowShirt
author_rank: Frequent Contributor
timestamp: March 29, 2014, 06:05:53 pm
content: Stainless steel?http://www.bipm.org/en/scientific/elec/calc_capacitor/current_status.html

author: Fsck
author_rank: Super Contributor
timestamp: March 29, 2014, 06:08:14 pm
content: surprised nobody has asked this yet. best for what?

author: CaptnYellowShirt
author_rank: Frequent Contributor
timestamp: March 29, 2014, 06:44:45 pm
content: Quote from: Fsck on March 29, 2014, 06:08:14 pmWhoa whoa... that'd make too much sense.

author: electronics technician
author_rank: Regular Contributor
timestamp: March 30, 2014, 12:59:41 am
content: Quote from: Conrad Hoffman on March 29, 2014, 11:50:47 ameletrolytic capacitor thanks for the replies