While adding a new lead to a pcb board by soldering iron touched one of the electrolytic Capacitors, and melted the plastic casing of the Cap.
Should I replace this Cap?
Electronic – Electrolytic Capacitors damaged while Soldering
capacitordamagesoldering
Related Solutions
You applied too much heat to the pads and they became detached from the underlying substrate (most likely fiberglass, not plastic).
I would use much less heat in the future and work at a quicker pace.
To fix, find the traces that would have gone to those pads. Scrape away some of the soldermask on these traces so you can solder to them.
Since the board is damaged, it's probably a good time to get creative to fix it. It looks to me like the traces are very near the damaged pads. I'd scrape some of the soldermask off and orient the capacitor such that it touches both newly-scraped trace. Then solder on a blob at each end .
Here's what I mean:
Scrape the dark green area to expose copper. Position the cap (if you are committed to using the original part - you can also replace with a leaded through-hole component and bend the leads to fit) so it will make a connection between the two. Also, it looks like the top trace continued where the lime-green box is, and is now broken. You will want to scrape away the solder mask there as well, and bridge the two traces.
Take this with a grain of salt, as I do not know your design or board layout and I'm just making guesses how to repair this exact board. I'm just offering techniques on how to remedy this in general.
In general the melted plastic won't stick to the PCB very strongly. A plastic or bamboo spudger will often remove it with a little pressure.
Best Answer
PROBABLY OK but cannot be sure.
If this is mission critical / life support / you really care, then replace it.
If it failing is no big deal then leave it and see.
In many cases it will be OK.
A modern "electrolytic capacitor" (usually an Aluminum wet electrolytic capacitor)is built inside an Aluminum can which serves as the negative connection. The outer plastic layer has no part in the operation of the actual capacitor - it serves as a means of insulating the can from accidental electrical contact and provides a convenient place to write information on. If you destroy the plastic that does not affect the capacitor in any way BUT heating the metal can will transfer some heat into the interior. A mild 'touch' is liable to have little or no ill effect but any strong localised heating may boil local electrolyte or cause damage through expansion of the material.
Experience suggests that there is enough heat-sinking in the can to allow the occasional light touch with no perceived ill effects in normal use. BUT ANY touch that causes significant heating MAY cause problems months or years later. If you care or it matters, and it was not an expensive capacitor, replace it. If not replaced, keep a small mental note for the future - and learn to solder even more carefully :-).