Aluminum Organic Polymer Capacitors?

roothorick

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Ever since the capacitor plague, manufacturers in the computer world have been getting away from electrolytic capacitors any way they can. Recently there have been a LOT of PC motherboards with different-looking capacitors. They're in an unvented aluminum can without a wrapper, a lot like you find really tiny SMT electrolytic capacitors in, except these guys are through-hole, and bigger -- a LOT bigger, many around 1/2" in diameter. Mouser seems to call them "Aluminum Oragnic Polymer Capacitors".

They probably haven't been around long enough to have much of a reliability record, but they've gotta be more reliable than the volatile electrolytics we're using now. Has anyone tried them on monitor chassis? Looking at what's available on Mouser, I'm not sure if they come in all the right values, but I thought I'd bring it up.
 
what capacitor plague?

if it's been discussed in length I apologize. Is it a case where a guy is buying bulk capacitors or cap kits and many of them are worthless or dead?
 
what capacitor plague?

if it's been discussed in length I apologize. Is it a case where a guy is buying bulk capacitors or cap kits and many of them are worthless or dead?

A *LOT* of capacitors were made with a defective electrolyte causing them to fail early (as in, months), particularly in PC applications where they were used to filter high-current low-voltage regulators for power-hungry CPUs. It happened pretty recently -- the bulk of them were discovered around 2007. The defective caps are still turning up regularly today.
 
I use them at work. Mainly for switching power supply sections. There are benefits to them but also some places where you aren't suppose to use them. I don't think they would work well for most caps in a monitor. Motherboard manufacturers use them for other purposes then the plague. The have a much lower esr for one.
 
I've heard that the Aluminum Polymer can sometimes be substituted (not sure if this applies to monitors) but a lot of times will require a substantial change in capacitance rating to achieve the same effect as the original. The Aluminum Organic Polymer cap has to be rated less than an equivalent electrolytic.

The capacitor plague relates to a bad mixture (from a bootlegged recipe) that many (mostly Chinese and Taiwanese) capacitor companies were using (and stealing from each other). They even went to the length of bootlegging the more popular capacitor company's capacitor designs (logos, etc.) to create black market versions of name brand caps.

http://en.wikipedia.org/wiki/Capacitor_plague

The greatest part about the stolen recipe was that (rumor has it) the missing ingredients were the most expensive components in the proper recipe, therefore giving the crappy cap companies almost limitless ability to undercut the competition. Therefore spreading the plague even further, as it offered so much capability for manufacturers to lower their cost. Once word got out about the problem (around 2007 like mentioned above), you started to see manufacturers (mostly of computer components) calling out the caps they used in their products by name brand, country of origin (primarily Japan) or stating that they were solid state. I was surprised recently in a pre-sales conference call with Enterasys (network switching company) that they went into great detail to show the processes they've gone through to entirely eliminate electrolytic capacitors from their power supply and mainboard design. Very impressive that they got into this detail. They said they monitored warranty RMA, and although their numbers were low they claimed they could be even lower. In reviewing what was actually wrong with returned units, they determined that the capacitors were one of the main things wrong. They went back to the drawing board to eliminate the caps from the design.

Add to the mix (pun?) that some "real" capacitor companies had issues with their legitimate caps during this time (2001 to 2004) and you get a recipe (pun?) for disaster.
 
I've heard that the Aluminum Polymer can sometimes be substituted (not sure if this applies to monitors) but a lot of times will require a substantial change in capacitance rating to achieve the same effect as the original. The Aluminum Organic Polymer cap has to be rated less than an equivalent electrolytic.

Why would this be? The polymer caps have a lower ESR? I would think then that it'd be a direct replacement for filter caps...
 
Why would this be? The polymer caps have a lower ESR? I would think then that it'd be a direct replacement for filter caps...

I can't think of any polymer caps that have a high enough working voltage to be used as an filter cap. Plus I wouldn't use such a low esr cap for an input filter cap.

Polymer caps are great for certain applications, this just doesn't seem like one. Switching Power Supplies, yes. Other Power Supplies and PCBs, maybe. For monitors, just use a nice low esr electrolytic cap like Panasonic or Nichicon.
 
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