NP0, stacked film cap orientation

We've found that surface-mount stacked film caps tend to fall apart when soldered and washed.

The ends are usually visually symmetrical, so there's no way to identify things.

This one is falling apart already!

Ugh. Thanks for reminding me of the last time I had to rework a precision anti-aliasing filter. 8-(

I guess the best solution is to use NP0 caps so small nobody would dare try to run a trace under them.

--sp

Tell them not to do that. Or make them run a ground.

We run traces under 0805s and sometimes 0603s.

I have seen some PDFs that indicate (say) left terminal being the "wrap-around". I think that typical construction is like taking your fingers and interleaving them, making (say) left terminal being the top foil. Check the PDFs carefully; different manufacturers will do this differently even among capacitive lines and values.

What's the reason?

Best regards, Piotr

Fantastic, was that an April 1st joke which someone forgot to remove?

I just forwarded it to a colleague who's a bit of capacitor specialist suggesting we might consider using it and he Skyped me back wanting to know what was so great about it. Then he clicked on the image.

Cheers

That's a riot. At least it's truth in advertising!

Cheers

Phil Hobbs

Sort of like pre-washed jeans, with the knees ripped out.

Troubleshooting is so much easier when you know in advance which part is dead.

Cheers

Phil Hobbs

The layers aren't stuck together very well. They seem to be made in long bars and then sawed up into individual caps. Most are sold like that, no side sealing. They delaminate and water can get inside and cause electrical leakage. Nasty little things.

When I need film caps, I usually go through-hole with epoxy-dipped parts.

This works ok,

but manufacturing has to be very careful with these, reflow temp and washing and inspection.

They are usable (well, not the pre-damaged ones) but you've got to be very careful about the assembly process. Never water wash if leakage matters.

Hardware expands to fill available space?

Thank you,