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Old February 25th 04, 08:51 AM
Ian White, G3SEK
 
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Tim Wescott wrote:

In the case of RF devices like DDS's and high-performance
microprocessors (you think 1GHz isn't RF?) the surface mount package
significantly enhances performance.


Re-mounting an SMD onto a DIP header guarantees minimum ground-lead
lengths of about a quarter-inch, so watch out for some "interesting"
changes in performance.

I haven't found them to be that bad to work with; you just need good
eyes and a steady hand.

I don't have notably good eyes or hand co-ordination, but have done
plenty of SMD work using an extra pair of strong reading glasses (on top
of my normal pair) and a Weller TCP iron with the finest-pointed conical
tip.

It's remarkable how your hands become much steadier and more controlable
when viewed under magnification. The other thing is to rest your elbow
or forearm on the bench, so you only have to move your wrist and hand.
Oh yes, and lay off the coffee and Coke for several hours beforehand!

Given those aids, anyone who doesn't have a clinical condition affecting
hand co-ordination should give SMD a try. (Note: "I don't want to" is
not a clinical condition :-)

Other essentials:
* a good work light
* thin silver-loaded solder (20g maximum)
* a flux pen or a supply of liquid flux
* thin fluxed desolder braid (1/8in maximum)
* a good pair of tweezers, that won't cross over and flip the SMD to
who-knows-where
* a clean workspace, because you *will* drop things

With only that equipment, I've mounted AD DDS chips (and much else) on a
board and they worked first time.


SMD work *is* do-able... so just do it!


--
73 from Ian G3SEK 'In Practice' columnist for RadCom (RSGB)

http://www.ifwtech.co.uk/g3sek