What cap mfr. to use?

Today I ordered electrolytic caps. It was frustrating. I had planned to get the best low-ESR replacements for all the caps in some switching power
supplies. I discovered how limited any one manufacturer's low-ESR catalog is. Many of what I needed (none of which seem to me to be esoteric values) were not available. A couple of times I had to leave a particular manufacturer's catalog altogether to find a value.
Which brings me to my question. I was trying to get all Panasonic FM-series (hi-temp, low-ESR) caps. I've heard good things about Panasonic's caps, but being forced to another brand I has no idea of comparable quality. (This, at Digi-Key and Mouser.)
Also, How important is the type of electrolyte? I've read that low-ESR caps are frequently made with water-based electrolyte whereas non-water-based formulae cannot give low ESR value.
The qualities of caps (ie, hi-ripple, hi-temp, low-ESR, etc.) are frequently discussed on electronics forum, but I haven't seen the different manufacturers compared.
How do the quality of caps compare by
Nichicon Panasonic Vishay / Sprague Mallory Rubycon United Chemi-Con Cornell Dublier Xicon
Feel free to add to the list, praise, trash, and/or list in order of your preference. Extra credit for essays on why you like / hate / prefer a brand or series of caps.
Thanks,
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"low ESR" is not good enough for a purchasing spec. By the standards of just a few decades ago, all of today's electrolytics are low ESR. But whether anything meets your requirement is driven by the requirement, not bullet points in the capacitor maker's glossies.
It's easy to find electrolytics of same voltage and capacitance which have ESR specs different by a factor of 10 or more. It shouldn't be too surprising that package and size have a lot to do with ESR. If your requirements are not met by any commercially available capacitors, you might think about making your design more realistic :-).
Digikey etc. let you sort by ESR.
It is also possible to choose capacitors which are too low in ESR and lead to instability with low-dropout regulators or other circuits.
Tim.
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On Thu, 7 May 2009 09:42:16 -0700 (PDT), Tim Shoppa

And a lot of, maybe most, switchers are stabilized by the filter cap esr.
John
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DaveC wrote:

The only one of those I haven't heard of is United, but that says nothing about the quality, I'm just not familiar. The others are all familiar and reputable brands, I wouldn't hesitate to use any of them.
Just go to digikey and find the values you need, don't worry too much about the brand or about having them all the same brand. Pay attention to the physical size and package style as it varies and often matters with compact modern equipment. They will be listed by temperature and by lifespan at that temperature. I have always used standard 105c "low ESR" capacitors as replacements in switching power supplies and never had an issue.
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How critically are you trying to match the values?
Please remember that 'lytics are manufactured and sold with a rather wide tolerance range. For example, the Panasonic FM and FC series have a +/- 20% tolerance specification, and the nominal values they list (in the Digi-Key catalog at least) are around 20-30% apart... so there's some amount of overlap between the values you'd expect to get.
Older caps were often sold with -20% +80% tolerance, which meant that you could end up getting quite a lot more capacitance than you had "paid for".
In most cases, these days, I'd just look at the space I have available to fit the cap, and then pick the "equal or next largest capacitance, equal or higher working voltage" to what the BOM calls for. Unless there was a particular need for a specific value (e.g. for timing purpose) I wouldn't sweat about things like "the BOM calls for a 220 uF, and all they have in that size is a 330 uF."
And, if there were timing issues involved, I don't think I'd be using a 'lytic at all in that application!

I've heard good things about Nichicon, and have used them in some repair/retrofit projects. Don't have anywhere near enough information about long-term performance to be of help with your question, though.

For what it's worth, I've seen several of the PC-motherboard manufacturers touting their use of solid-electrolyte capacitors for the CPU VRM... and this is a high-current, high-ripple, low-ESR- is-very-important application. One manufacturer was citing a "50,000 hour" lifetime figure on the motherboard carton (although I think this assumes very good cooling of the board).
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Are you sure there isn't a microdot in the small print with the words "electrolytic capacitors excepted" printed on it?
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Mike Tomlinson wrote:

"lifetime" is a word of dubious interpretation. Does it mean that it won't break in that time, that it can be repaired in that time if it does break, or something else?
If they claimed an MTBF of 50,000 hours, that would be different.
Sylvia.
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On Fri, 08 May 2009 22:04:27 +1000, Sylvia Else

AFAIUI, MTBF typically applies only to the flat part at the bottom of teh bathtub curve. They conveniently hack off the infantile failures at the left and the increasing failures as the useful life expires on the right. IOW, a product can have a much higher MTFB than the time it takes to wear out.
Also, 50,000 hours 24/7 is only 5.7 years, which is more-or-less what you'd expect out of a motherboard.
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Spehro Pefhany wrote:

And if you run a 105C cap at 40C you'll get ~ 85 times the datasheet lifetime. So a 2,000 hr 105C cap would last over 19 years. Watch the ripple current of course !
Interesting point there. One decoupling cap on a mobo of mine near the graphics card slot was visibly bulged whereas others weren't. I imagine it was hot air being blown onto it by the GPU fan.
Graham
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On Fri, 08 May 2009 14:55:18 +0100, Eeyore

I would imagine that it was a crappy capacitor, perhaps one of those knock-off Taiwan caps. Sceptre LCD monitors had a rash of crappy electrolytics which they used on the outputs of their switchers a few years ago. Many computer motherboards also used icky caps. The two Sceptre monitors that a friend had crapped out around the same time. I replaced the high stress caps with United Chemicon caps.
For my pulse power amplifier applications, I stick to United Chemicon.
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Which series do you use? U-C make several qualities in radial lead cans.
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KZE
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Not from electrolytic caps, which was kind of the point. Even Panasonic specify only 10k hours for their top of the range electros.
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wrote:

I guess that would be a rather serious problem if the temperature inside your computer case averaged 105C = 221F.
http://www.loc.gov/rr/scitech/mysteries/friedegg.html
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Seen a modern mainboard recently? Voltage regulation MOSFETs with heatsinks on, some with their own extractor fans? Heat coupled to the capacitors by a few millimetres of thick copper PCB trace for excellent heat conduction?
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wrote:

Certainly.

Have you put a thermocouple on the capacitors?
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Spehro Pefhany wrote:

You need a themocouple and a suitable meter for that ! ;~)
Graham
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On Fri, 08 May 2009 17:12:11 +0100, Eeyore

Really? ;-)
Of course many, if not most, portable multimeters have type K thermocouple inputs (of dubious accuracy, but good enough for this sort of thing) and many are supplied with a bead thermocouple.
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Spehro Pefhany wrote:

Funnily enough, often some of the cheapest ones have the thermocouple input but I used to keep a supply of type-K themocoouples anyway. I like keeping an eye on temps.
Graham
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Mike Tomlinson wrote:

Point 1: You can ventilate your case and CPU far better than 'normal' methods.
Point 2: leave the side panels off like I tend to do !
Graham
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