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Brian Guralnick 2nd October 2003 01:08 PM

Is this SMD Metallized Polyester Film Cap any good?
I' been told that Film caps are the best.

I've finally found a reasonably low priced 10uF, 30VAC SMD Metallized Polyester Film Cap from Vishay. It's for a DC filter at the line input stage of my amp. It's output load is 100k. Is it any good? Should I still search for better Film caps?

ds link >

Maybe I'm better off with a through-hole box style. 10uF, 40VAC.

ds link >

peranders 2nd October 2003 01:16 PM

Polyester is polyester, not bad at all. You could try PPS, polyphenylsulphide (not sure about the spelling).
I'm not sure if 10 uF is available.

Check C1 och C11 at the picture

I'm quite pleased with them.

Brian Guralnick 2nd October 2003 02:09 PM


liz 2nd October 2003 03:43 PM

I'd stick to SMT wherever possible, in order to minimise lead inductance. Plus it will give you more flexibility in terms of layout.

peranders 2nd October 2003 05:03 PM

One disadvantage may be not so many types or values otherwise only positive things, except for heat resistance in industrial soldering (oven).

Brian Guralnick 2nd October 2003 05:44 PM

Ok, do I have these cap in correct order by quality?

Metallized polyester (PET) SMD Film Caps. Basic foil quality.

Metallized polyethylene naphthalate (PEN) SMD Film Caps - Higher quality.

Metallized polyphenylene sulphide (PPS) SMD Film Caps - Highest quality.

peranders 2nd October 2003 07:09 PM

Something like that but plastic SMD caps are difficult to make resist high temperature. This is also a "quality" aspect. Good electrical data but hopeless to solder, not very high "quality". Put a pcb in oven 250 deg C warm or warmer is something else compared to ordinary wave soldering. But if you shall do the soldering by hand you can disregard this temperature thing.

Brian Guralnick 2nd October 2003 09:47 PM

How do you feel about SMD mica caps?

peranders 3rd October 2003 06:16 AM

If you are asking me: I don't know because the only plastic cap I have used so far is PPS EVOX RIFA. At work I avoid plastic. I haven't had yet a single really sensistive application which demands plastic caps.

markp 10th October 2003 05:52 PM

Try to avoid smd mica or ceramic caps as they get stressed under expansion/contraction of the pcb during temp changes and can change in weird ways, like piezo effects. The very minimal inductance of a straight piece of wire is moot. IMO I'd always go with through hole caps. Also, film and foil is generally better than metallized but much more money.

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