On Mon, Mar 19, 2018 at 11:19:02AM -0400, Steve Litt wrote:
> On Mon, 19 Mar 2018 14:11:53 +0000
> ael <adrian.lawrence@???> wrote:
>
> > On Mon, Mar 19, 2018 at 05:24:26PM +1300, Daniel Reurich wrote:
> > > They're all thru-hole and can be done with a fine tipped soldering
> > > iron and cheap plunger type solder sucker..☺
> >
> > As someone with a fair amount of experience of soldering, I must say
> > that you have been lucky with exceptonal thermal isolation in the
> > motherboard. Most multilayer boards need a bit more than
> > just a fine tipped iron. I would expect to need at least a hot air
> > "hotplate"
>
> > and a beefy temperature controlled soldering iron.
>
> U mean like this? https://tinyurl.com/y9ka2k4m

That would probably do for the soldering iron aspect, although they are
rather expensive. There are perfectly adequate cheaper options,
especially if they are only for occasional use.

However, this is really missing the point. You have to raise the
temperature to above the solder melting point (obviously), and to
do that you need to supply enough thermal energy. Doing that via
conduction along the leads of a capacitor can be difficult, requiring
excellent thermal contact between the soldering iron & the lead.
More importantly, you have to overcome the thermal conductivity of the
multilayer board conducting the the heat away. Having designed multilayer
boards, one of the challenges is to provide thermal isolation pads
around the through-board holes for leaded components to make rework
of this sort possible. Not easy. As a rule you also need to heat the
area around the target with something like a hot air unit in addition
to the solder iron to have a decent chance.

I suspect that most modern designs don't cater for rework, so it is
even harder to remove components without destroying the board. Of
course, surface mount is easier and much more common nowadays, so
some of this is historical.

ael