Hi all
When you say that a HASL board did not wet do you mean that there was no
increase in solder volume on the pad?  I.E. that the pad geometry looks like
it did before going through the wave?
Did the past revision use the same coating?
Is the HASL coat extremely thin? could be mostly intermetalic
When you had a non-wetted pad with a component on it did the component wet
and not the pad?
Could an operator have brought in something contraband with silicone in it?
Did maintenance lube something with silicone spray?
Still sounds mechanical though.  The glass plate would be in order. good
luck
John Thorup
> -----Original Message-----
> From: Stephen R. Gregory [SMTP:[log in to unmask]]
> Sent: Wednesday, April 04, 2001 2:54 PM
> To:   [log in to unmask]
> Subject:      Re: [TN] Random absence of soder joints
>
> Hi Ioan!
>
> Are you seeing this problem on every single board, or on random ones? I've
> run into something similar before in the past...
>
> It all went back to our operators. Seems that when they found a board that
> had glue problems before populating it, they would take a kim-wipe and wet
> it
> with alcohol to clean the glue off and re-run the board again, instead of
> sending the board through the automated cleaner where it would be cleaned
> thoroughly.
>
> Just wiping the board off doesn't cut it...you may visually look at it and
> it
> may appear that all traces of glue have been removed, but there will still
> be
> a very thin coat that's
> practically invisible that will prevent solder from wetting during wave.
> You'll be able to hand solder it fine when you stick a 700-degree
> soldering
> iron to cause it'll burn right through it.
>
> Seen exactly the same things as you when it was happening to me in the
> past.
> One pad would solder and the other one wouldn't...the one that didn't
> depended on which direction the operator had used when he wiped the board
> off...and sometimes the glue would get on both pads, or on locations where
> there wasn't any components and the solder wouldn't wet...
>
> Your situation sounds suspiciously like mine...
>
> -Steve Gregory-
>
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