I believe you will find it more difficult to solder a wire into a hole
already plugged with solder.  It will take more heat and longer dwell time
to reflow the solder before being able to insert the wire into the hole.  It
will also be difficult to get a good joint because by the time the solder
plug has melted, the flux would be used up and not benefit the wire.  The
longer solder iron dwell time puts the board and PTH at risk for burning,
measling or lifting. (depending on how thick the board is)  A solder joint
made to a clean/clear hole is faster, requires less heat input and is
preferred.

R. G. Blomberg
Honeywell - Space Systems
Staff Production Engineer



Kiiski Jarmo wrote:

> I have a question about hand soldering of a wire to solder plugged via.
> Nowadays there is a temporary solder mask (TSM) preventing the soldering
of
> these plated through holes at wave soldering machine. After wave soldering
> the TSM is removed and the wire is soldered to hole at assembly. Now I get
> this great idea! What if we just leave the TSM out and let the holes to be
> filled with solder. At assembly the solder will be melted and wire will be
> placed to hole and the solder joint is formed with proper final heating
and
> cooling.
>
> What problems or risks can be expected, when doing such soldering? Are the
> joints as reliable as normally? I won't like to remove the solder before
> placing the wire, I would like use it to form the solder joint to save
time.
> Would I need some extra soldering wire or flux?
>
> Have a nice weekend
>
> B.R.
> Jarmo Kiiski
> email: [log in to unmask]
>

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