Judging by the fact the same yellow residue is around other soldered
joints on the board, it's more than likely just the the flux hasn't
been washed off properly.
Leaking batteries are usually more obvious as the end plates and
terminals of the battery appear white and "frosted".
With the wave soldering process, most manufactures are now using
"environmentally friendly" water soluable flux.
After the wave soldering process, the boards are sent through a flux
removal process, which if not set up perfectly, often does not remove
all traces of the flux. The flux then dries and forms a yellow/white
powdery residue around the soldered joints.
Sometimes this can appear like liquid (water) corrosion.
As the flux is heat activated by the soldering process, it's innert at
room temperature, so should not cause any problems by leaving it on
there.
The worst thing that might happen, is that in very a high humidity,
the residue may absorb moisture from the air, and cause some minor
electrical conduction between soldered joints, causing equipment
malfunction.
If it concerns you, and you really want to remove it, the best thing
to use is a product called "fluxclean" made by Electrolube.
The next best choice is isopropyl alcohol.
If you want a more accurite opinion of the problem, send me a high-res
image of the effected areas.
Anthony.
