It most probably was a dedicated wave pallet and could have had top side
hold downs. This would make more sense with a mass produced PCB.


Jason Gregory
Manufacturing Engineer
Innova Electronics
(281)653-5593
(281)653-5594 fax
(281)594-0602 cell
[log in to unmask]

-----Original Message-----
From: TechNet [mailto:[log in to unmask]] On Behalf Of Stadem, Richard D.
Sent: Tuesday, April 18, 2006 9:18 AM
To: [log in to unmask]
Subject: Re: [TN] Selective Soldering

It is typically done using a fixture made of Durostone. This prevents the
selective solder process, whether wave-soldering or selective fountain/jet
soldering, from filling other holes or pads where solder is not desired.
Some examples of these types of fixtures can be seen at www.dmipallet.com.
These people make these fixtures and are the best in the world at it.
Believe me, I know, I've tried them all.
Another method would be to use a temporary solder maskant that is available
in peelable or soluble form (peelable, low ammonia is best).
Both will contaminate your wash process, the peelable less so depending on
how diligent the operator is at removing it prior to wash. Even when peeled
some residue will remain on the pwb.

-----Original Message-----
From: TechNet [mailto:[log in to unmask]] On Behalf Of Wayne Thayer
Sent: Tuesday, April 18, 2006 8:46 AM
To: [log in to unmask]
Subject: [TN] Selective Soldering

While inspecting a board produced by mass manufacturing techniques, I
noticed the backside had been selectively soldered.  The areas where through
hole components are located appear to have been gasketed off (as detected by
observing the no-clean flux residue) by either the fluxing or wave-like
processing.  Any ideas as to how that was done?  Its clear that the board
wasn't wave soldered as there are open PTH's in the areas not soldered.  A
multi-nozzle solder fountain?

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