Originally Posted by jsc1973
Not as horrendous as some I've seen here, but this is the motherboard in a friend of mine's eMachine. It quit booting up, and you can see why:
Not much in the way of leakage, but they're bulging on both the top and the bottom. And the worst part:
These appear to be phony Panasonic capacitors. I don't think two real ones would fail when all they had to power was an Athlon II X2 at stock.
They are not fake.
At least, they don't look fake to my eyes. And that's not the first account of prematurely failed Panasonic capacitors. More than a few exist on badcaps.net and on a select few sites otherwise, but not in such disconcerting volume that they would be considered as bad as NCC's KZG and KZJ (the prematurely failed ones are of the FJ, FJS, and FL series, equal to HM and HN respectively). Unless it's just the image, I think I might see some slight discoloration around that area of the PCB which means the FETs on the VRM output might have become very hot (possibly giving light as to the reason for the failure in question).
In those ultra low ESR capacitors, though, the high amount of H2O in the electrolyte has a tendency to aggressively react with the aluminum oxide layer and essentially thins it until it's gone and only the aluminum foil is left, causing hydrogen gas to form and eventual dry outs (aluminum hydration). You can use inhibitors and oxidizers to reduce the effect but that's all it does, prolong the effect (even if for a rather long time if good neutralizers are used). Combined with the fact that the highly aqueous electrolyte expands and dries out considerably with heat, I don't think they're designed to live forever. That's why most of their datasheets only rate their load life to be about 2,000 hours @ 105*C. And this is why KZGs and KZJs are so bad. KZGs weren't discontinued, though, at least not as of 2 years ago, they are just sold directly to OEMs now. I don't think those MCZs are fake, either - MCZs are renowned for their high sensitivity to heat.
I know these premature failures might make those Panasonic capacitors seem incompetent but the secret to attaining a good chemical stability relative to electrolyte maintaining low resistivity with a good dielectric constant and strength is a highly guarded one and it's no easy feat, especially if you consider how many different water-based solvents exist out there (the different combinations of acids, alkalis, or salts might not always have great long term stability). Electrolytic capacitors employ and obtain conduction by way of ions which makes it very difficult to lower the ESR and increase the conductivity. Solid state capacitors (polymers) do this by way of electrons and their conductivity and stability is much, much better - as far as conductivity goes, the improvement is in the order of over a hundred fold.
Your Panasonic capacitors of many decades ago probably haven't failed because they employ different types of electrolyte. Electrolyte in capacitors can be roughly grouped into three types:
1. Glycol or borax solutions. These kinds of liquid electrolyte have a low amount of water relative to the very low ESR capacitors but still have a long term unwanted reaction to the water, resulting in dry out (very long, though - think 20 to 30 years, by which point the rubber bungs would decompose and the electrolyte would leak anyway).
2. Organic solutions such as Y-butyrolactone or something similar. These are essentially free of water and have very good characteristics and long term stability.
3. Water-base electrolyte with roughly half of its content or most of it comprising of the H2O needed to lower the ESR and increase conductivity.
Of course, there's always a chance that they could be fake. Fakes with concentric, cheap, bullseye flat bungs in place of the thicker bungs have been spotted on genuine motherboards before so anything is possible. But I don't think they're fake.Edited by Wester547 - 5/20/15 at 1:41pm