Dear Technet,

Whenever, I'm running a 100% through-hole board, that is densely populated
with mainly DIP components, and a only few capacitors and resistors., 20 to
30% of the solder joints are gritty. 

It had never happened to board of mixed technology.
I have sent the solder for lab. analysis, and the result is within the
recommended specification.

The Board is :-
10 x 10 sq.inch
4 layers 

The wave-solder Machine used :-
The wave-solder machine used is SEHO 2000 - a full-blown nitrogenous tunnel.
The solder pot temperature is set at 245 deg.cel or 473 deg.F.
The top side temperature is measured at about 194 deg.F / 90 deg.C.
Conveyor speed is set 0.90 metre/minute.
The solid content of the flux is 1%.

Could anybody advise me why this is happening, and how to solve it. Our
rework operators are touching every gritty joint.


Poh Kong Hui
Nera Electronics