Electrical Engineering Stack Exchange is a question and answer site for electronics and electrical engineering professionals, students, and enthusiasts. It only takes a minute to sign up.
Sign up to join this community
I recently unpacked my 8 year old Creative SBZ from storage, has been lying there for 4 years and noticed these white spots on the pcb. Can someone identify what these spots are?
Sorry, the pcb was covered in dust.
Update: The card was working flawlessly when I packed it. There were no marks on the PCB. Also, I didn't plug it in yet.
Just for reference here is another card that was stored with my SBZ.
Corrosion (what remains of those screw heads in the middle of the photo) and white residue indicate the board got wet (maybe sitting in water for a long time). If it was sitting in a cardboard box, wet cardboard will hold the water against the board and assist the corrosion. Water, without electricity, won't corrode copper (much) so the traces are probably okay.
If it was not powered when it got wet it may still function when cleaned.
The other stuff looks like dust that got wet.
I would definitely clean it with a toothbrush and (preferably) 99% isopropanol or, failing that, just soap and water.
The white spots are just leftover flux from when the board was assembled. Those 0.100" pin connectors were likely hand-soldered and some flux residue was left on the board. This is normal and doesn't impact the functioning in anyway.
Not all fluxes are created equal though. Many will begin to corrode metals if they aren't cleaned completely off the board.
On the other hand, there are fluxes called 'no-clean' fluxes that are inert and do not need to be washed off. This is the kind of flux you'll find leftover if a PCB has any residue.
All of the no-clean fluxes I've seen turn white if they're exposed to water.
Note that this does not mean the board got wet. If it was in storage, it would have been exposed to ambient humidity most likely. If it was stored somewhere and there was periods of high humidity during those 8 years, this would also turn those residues white.
In summary: it's harmless. Don't worry about it. If the device has any issues, it isn't from the white residue.
