Electrolytic capcitor electrolyte corroding the aluminium can

[japlytic]

I've seen electrolytic capacitors which had a chemical which gradually ate through their aluminium cans under the plastic label, eventually causing it to become rough.
Have you ever seen something like this?

[PCBONEZ]

Re: Electrolytic capcitor electrolyte corroding the aluminium can

Some caps have vents in the side of the can under the sleeve.
Probably most common in 5 or 6 mm caps with no top vent.
Not something I ever actually look for so I dunno how common it is but I've seen it.
.

[shovenose]

Re: Electrolytic capcitor electrolyte corroding the aluminium can

Huh?

[stj]

Re: Electrolytic capcitor electrolyte corroding the aluminium can

i'v seen caps with rough sleeves - it's caused by the cap getting seriously fucking hot because it cant handle the ripple!

[Quasar]

Re: Electrolytic capcitor electrolyte corroding the aluminium can

Wasn't the bad electrolyte era the cause of that? Are these new(er) caps or from back in 2000-2005?

[PCBONEZ]

Re: Electrolytic capcitor electrolyte corroding the aluminium can

Wasn't the bad electrolyte era the cause of that? Are these new(er) caps or from back in 2000-2005?

Got new for yah.
The bad aluminum era has been around for decades and still is.
It does the SAME thing as bad electrolyte you are referring to, it's just a little slower.

[PCBONEZ]

Re: Electrolytic capcitor electrolyte corroding the aluminium can

Huh?

Which word did you need help with?

[Quasar]

Re: Electrolytic capcitor electrolyte corroding the aluminium can

Got new for yah.
The bad aluminum era has been around for decades and still is.
It does the SAME thing as bad electrolyte you are referring to, it's just a little slower.

Oh, ok. I thought the question was about electrolyte eating through, so it doesn't matter. Bad alum or bad elec.

Could it be something in the label reacting with the alum.?

[PCBONEZ]

Re: Electrolytic capcitor electrolyte corroding the aluminium can

I didn't mean it that way.
My point was there is more than one plague.

The 'stolen electrolyte plague' [2001-2005?] and the 'low purity Aluminum plague' [anything from Taiwan or China since forever] 'plagues' are indistinguishable without actual chem lab tests.

Additionally Taiwan or China manufacturers no doubt have other marginal electrolytes that don't have anything to do with the famous stolen formula story.
They don't need to buy bad electrolyte, they can make their own bad electrolyte.

There is also that all the 'stolen electrolyte plague' caps also suffered from the 'low purity Aluminum plague' meaning they got a double whammy.

Hard to say which of those two problems would be the root cause of corroding Aluminum.


CALCE [Center for Advanced Life Cycle Engineering] is a Failure Analysis Lab at the University of Maryland.
They went looking for the bad electrolyte issue and tripped over the impure Aluminum issue.

.

[japlytic]

Re: Electrolytic capcitor electrolyte corroding the aluminium can

The capacitors I was mentioning were around the late 80s-early 90s.

[PCBONEZ]

Re: Electrolytic capcitor electrolyte corroding the aluminium can

I haven't seen it but I hardly ever see anything that old.

Some particular brand or something you see once in a while generally?

I can see a couple few different ways that might happen.
Too thin or bad aluminum in the can.
Electrolyte that is or becomes acidic.
Some acidic residue between the can and sleeve.

.