Re: New project...PCI based servo control board

[Robin Szemeti <robin-at-redpoint.org.uk>]

On Thursday 27 March 2003 17:06, Jon Elson wrote:
> But, I really can't imagine hobbyists are going to
> want to solder
> in a 144-lead chip with 1/2 mm pin spacing!  I have had to work hard to
> develop
> the techniques to do this myself, by hand. 

Well, in a previous existence I worked as an electronics engineer performing 
board level repair on this kind of stuff ... in a word its *very* easy if you 
have the right tools. Surface mount stuff looks hard, but really its quicker 
and easier than through-hole mounting.

The trick with that sort of package is to use a solder cream, and a spot of 
superglue.  You place the solder cream in 4 thin lines, one down each row of 
pads .. a spot of glue under the chip and then place it with a vacuum pic and 
place tool, move carefully to align a pin with a pad on each corner, and let 
the superglue do its thing ... then just run a soldering iron with a 2 or 3mm 
chisel tip along each row of pins, just put the iron on at one end, and drag 
it slowly across those 36 pins ... the surface tension will seperate the 
solder and each pin will be perfectly soldered. You get better results if you 
use a spray on flux as well.  Total soldering time, less than 30 seconds.

If by chance you do get 2 pins soldered together, a sharp pointy pencil and a 
fine iron will undo them in a flash.

Try it on an old chip or two, it works very well with a little practice.

-- 
Robin Szemeti

Redpoint Consulting Limited
Real Solutions For A Virtual World