Are the "gritty" solder joints only in one area of the board or scattered 
around?  Are they only noticed on one or two component types?

Why are the joints being touched up?  is it because they don't meet hole 
fill specs. or is it a cosmetic issue?

What is the dwell time of the board in the solder wave?  And is the 90 Deg.C 
temp. a maximum topside temperature reading or is that topside temp before 
solder wave contact?
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From: TechNet-request
To: Technet
Subject: RE:ASSY:
Date: Tuesday, May 14, 1996 21:10

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