[sdiy] Cheap microscope for SMD

[Joe Grisso]

On Wed, Feb 17, 2010 at 6:58 PM, Paul Perry <pfperry at melbpc.org.au> wrote:
> I've always found those headband type magnifiers
> easier than the big desk mounted magnifying lenses
> (which tend to give me nausea as I peer into them).
>
> http://ucanhealth.com/compare.php?item1=580-3&item2=1200
> not the exact ones - mine are cheaper hobbyist types.
>
> Cheapest of all is a stacked pair of +3 generic reading spectacles
> from the dollar shop..
>

Nah, cheapest of all is soldering a 0.5mm pitch 100-pin QFP without
magnification.

Granted, I did have a headache for the rest of the day... so maybe I
should factor the cost of acetominaphen into that.

Honestly though, 99% of the fine-pitch soldering stuff I do is > 1.0mm
pitch, and I've been happy using a photographer's loupe on that stuff.
I've found that the three biggest factors in high-precision SMT work
are:

1) solder mask on PCB. *I can't stress this enough*
2) Flux. Flux. Flux. I started using a flux pen. It wasn't enough. Get
liquid flux and a needle bottle. Use liberally.
3) The right tip for the right job. Since I'm a Metcal advocate
(SSC-745A tip yo!), I won't elabourate on that point. If you
touch-and-go on QFPs and PLCCs, then get the sharpest tip you can for
the work. The one I mentioned above is a 60 degree 0.4mm wide tip. If
you blob-and-drag, then use what's called a drag hoof or micro-hoof
tip. It minimizes the solder bridging and carries the blob along with
the tip via increased surface tension.

Even though I've been VERY frugal and masochistic in my soldering
lately, I still yearn for a proper trinocular scope, fiber ring light
and double-bar boom stand with clutched X-Y table. *swoon* Someday...

-- 
Joe Grisso
Detachment 3, Ltd.