New, unused capacitors bulging?

[japlytic]

Twice I have seen an electrolytic capacitor (new - never used, never had a volt applied to it) which has bulged over time. Both were different brands.
Can anyone throw some light on this matter please?

[c_hegge]

Re: New, unused capacitors bulging?

https://www.badcaps.net/forum/showthread.php?t=8312

[stj]

Re: New, unused capacitors bulging?

not seen that, i had some shit ones that leaked around the wires though!

[severach]

Re: New, unused capacitors bulging?

I got in a pack of 10 motherboards that sat for a year. Never used or seen heat other than factory construction and testing. About no name 10 caps on every board were bulged. Board quality was very low and it was easy to burn traces so the dual P3 boards were scrapped.

[japlytic]

Re: New, unused capacitors bulging?

I've been told that a chemical reaction occurs (which produces gas and makes the capacitor bulge) in the capacitor if there are two incompatible chemicals and metals inside it. What might those chemicals and metals be?

[sofTest]

Re: New, unused capacitors bulging?

Are you sure it's not just a dud (from the forming at the factory), that slipped through quality control? Or did it bulge while in your possession? I received one in a lot I bought a good while ago.

[japlytic]

Re: New, unused capacitors bulging?

The capacitor in question was not bulging when I received, but over time, it bulged, even though it was not soldered in a circuit.

[TheLaw]

Re: New, unused capacitors bulging?

That doesn't make sense. Something must have happened....atmospheric pressure or something....

[Per Hansson]

Re: New, unused capacitors bulging?

It makes perfect sense, the electrolyte activated with the impurities in the aluminium and created gases, since it is a closed container something has to let go...

[TheLaw]

Re: New, unused capacitors bulging?

Then wouldn't you think that would happen more often?

[c_hegge]

Re: New, unused capacitors bulging?

I've seen it happen myself once too (since I posted that link to the thread). We ordered a brand new PSU at work and it had fuhjyyu caps. They were bulged even though we never even fired the PSU up.

[TheLaw]

Re: New, unused capacitors bulging?

I suppose if the material used is absolutely crude. Junk aluminum and junk electrolyte. I could see something bad happening.

But I wouldn't expect that in a high quality cap.

[c_hegge]

Re: New, unused capacitors bulging?

The only time I've ever seen a new good cap was a Panny I ordered, although I'm pretty sure it was just a manufactured dud that slipped through the QC Checks, but fuhjyyu is the only brand I've known to bulge just from sitting on the shelf.

[brethin]

Re: New, unused capacitors bulging?

Must have been a really bad batch or stored improperly for them to do that. Within spec a cap should never produce enough gas to vent never having been used and properly stored.

My guess is they were exposed to heat for a period of time. We all know even a new cap tossed in a fire will explode.

[yyonline]

Re: New, unused capacitors bulging?

I bought a new old stock Slot A board on eBay a few years ago...Jetway if I remember correctly. It was definitely never used, still sealed in the box. That said, it was 10 or so years old. It was full of GSC caps, most were bulged. I don't know what kind of conditions it was stored in, obviously.

[Pyr0Beast]

Re: New, unused capacitors bulging?

I've seen caps bulge even after you heat the PCB from lets say, graphic card.