polymer aluminum caps

The previous post reminded me:

I've started using polymer aluminum caps, the United Chem-Con
surface-mount ones. They seem ideal: very low esr, no explosive
mechanism, potentially long life, cheaper than tants, and capacitance
holds up at -40C.

I tested a couple of 100 uF, 16 volt parts. Forward leakage is low,
reverse leakage similar or a bit less than a wet lytic.

I slowly increased the voltage and, unlike a wet cap, the leakage
didn't go up much. At about 35 volts, it suddenly failed shorted,
which seems fair to me.

Pretty good so far. Anybody got experience or advice about these
things?

I've read that moisture may degrade the polymer, and cause a loss of
capacitance over time, but I don't know the numbers. So I guess it's
prudent to overkill a lot on capacitance, which is generally easy,
since they are pretty dense.

John

 

One of my customers is using Sanyo polymer caps. We used them to tame high
ripple currents power supplies.

I get them from
http://www.capacitorsplus.com/
http://www.capacitorsplus.com/sanyo.htm

Very nice company to deal with.

Regards,

Boris Mohar

Got Knock? - see:
Viatrack Printed Circuit Designs (among other things) http://www.viatrack.ca

void _-void-_ in the obvious place

 

What kind of pulse voltage rating do they have?

Ed

 

I've used the Panasonic Al polymer caps in medium current (6 Amps)
switching power supplies. Work great and haven't had any problems,
even when pressurized to 10,000 psi. They do have very nice qualities.

 

I don't think they do. And the highest voltage rating I've seen is 16.

John