White residue on IC connections???

[groovejet]

Im fault finding on a copier pcb and have come accross a few IC connections with a white residue on?

Am i correct in thinking its Oxidizeation(spell???) if so........

.....is this due to the pins not being used ???................Or somethng more sinister

Thankyou
Paul

 

[(*steve*)]

There are a number of reasons:

1) it could be corrosion from exposure to salty air
2) it could be corrosion from whatever was used to clean the boards after soldering
3) It could be corrosion from something being spilt on the board.
4) it could be corrosion from current passing across 2 dissimilar metals in a humid environment
5) it may not be corrosion

A (sharp) photo would probably help a great deal.

 

[groovejet]

Hope this helps, although id already removed the residue, but if you look at pin 4 its duller than the restof the pins.
All other pins are bright soldered but pin 4 is dull like a dry joint???

Thanks for the v.fast responce on the problem

Paul

 

[groovejet]

Pin 4 had a white solid residue starting from leg of IC, closest to the chip to half way down the leg?
There also was one IC with 2 pins with residue on
Here another pic, sorry but im using a Nokia 5530, so not the best!

 

[davenn]

doesnt look anything serious, mainly flux residue,
clean it off with a bit of spray can circuit board cleaner and an old toothbrush
2 items that should be in every tech's toolkit

Dave

 

[shrtrnd]

Yeah, I'm with davenn.
That white residue is leftover from the board assembly process at the factory.
One thing I'm starting to notice also, is some new spacer pads (to get the component up off the board during assembly), that the manufacturer (who I can't remember right now), CLAIMS 'dissolves and washes away', when the board is completed and washed in the manufacturing process. Maybe some of these 'dissolvable' pads aren't dissolving so good. Or maybe the manufacturer is not cleaning his board washing tanks good enough to handle the board residues (as in, 'washing' the board with contaminated water).
I guess it doesn't matter who's copier it is, ...the boards are probably all made in China now.

 

[groovejet]

thanx very much 4 ur help