The reason there are so many methods with none outstanding would point to my
thought that they are all appropriate for different situations.
Take the paste vs. wire issue just as an example: paste is obviously
advantageous in production situations where the process is automated and
well controlled. It can be made to work for rework and 1-offs while giving
cosmetically appealing results, but requires a certain skill set.

Contact type tools are costly, but are perhaps easier to use by folks who
value manual skills and technique.

There's also the comfort level to consider. Some people are just not
comfortable with contact soldering fine-pitch parts, and they seem to adapt
to paste & hot air or IR. For others apparently just the opposite is true.

I have carpal tunnel syndrome and new eyeglasses, so for me, automating any
of the placement is a big plus, whether paste or parts, 1-off or production.

My point is that search as we may, I don't think we'll find a method that
can be labeled as "best". The way to get into it well is to pick a method
and work through it. In time most people use several methods and have
several sets of tools anyway, so I say to anyone that hasn't yet - just jump
in and give it a go.

>     Most of the discussion on this board seems to be related
> to hot air
>     systems like http://www.zephyrtronics.com/home.html.
>
>     The instructor at the local community college where I am taking
>     assembly classes prefers a contact system like Metcal,
> which is what I
>     am using in class.
>
> I've used both at work for some stripping components from
> dumpster-diving
> finds.  I think the hot-air system has significant advantages
> for rework
> sorts of situations - it has a smaller chance of physically
> damaging the
> components or boards.  The fancy metcal tips for heating all
> the pins on an
> SMT part at once seem to be rather a pain to use.  On the
> other hand, I
> can't imaging using a hot-air system for simple assembly with
> normal wire
> solder.  I haven't done assembly with solder paste, so I can't comment
> there. (Hmm.  I've never seen any solder paste around here,
> which would
> seem to imply that our "pros" use the metcals for "adding"
> parts as well.)
>
>

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