>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
>