Homebrew PCBs

On 12/03/2010 11:55, William Laakkonen wrote:
> Hand Soldering any QFP requires:
>
> 1. Apply flux from mini-fluxer pen or similar
> 2. Position chip
> 3. tack solder opposite corners
> 4. glob solder across all pins, shorting most
> 5. lay a *good quality (E.G. M.G.Chemical) Solder Wick across the globbed
> solder on one side and drag the iron across the wick, lifting nearly all the
> solder, repeat this for other sides.
>
> It may be scary to consider globbing solder on a $20 chip- I've done it
> hundreds of times on QFPs now and have yet to lose a part.
>
> Elapsed time for an Atmega2560 (100 pin TQFP) about 5 minutes and no oven,
> paste, etc. Mind you I *have* used paste, hot air, solder mask.-, etc. I've
> used the above method successfully also with .35mm pitch parts since about
> 1992 and have done it hundreds of times. No special skill or tools needed,
> other than a good magnifier which you should have working with small items
> anyway. I'm not a young guy either, so I must work with the magnifier lamp.
>
> After soldering many thousands of SMDs, my conclusion is in most cases,
> solder paste is a wasted effort unless your in production. If you can see
> it, you can solder it with a (good)  pen, solder, and wick. I use 0.015
> solder for 0603 and up. I use .022 or 0.035 for QFP or SOIC devices and wick
> up excess. I only see hot air and paste useful for things which you cannot
> reach with an iron (flexible kapton boards with blind connects, BGA, ETC)-
> and what hobbyist(s)) would use such parts unless they were free? I do see
> "homebrew" in the title, which to me evokes a sense of doing more with less
> and experimenting with new techniques.
>
> Loading and soldering is only one side of a homebrew_PCB.

I drag-solder the leads with a mini-hoof Metacal cartridge. It's just as 
quick and no cleaning up with desolder braid is needed. Plenty of gel 
flux is essential.

Leon
-- 
Leon Heller
G1HSM