Archive of the former Yahoo!Groups mailing list: Homebrew PCBs

If you start to make a P&P that work ,,think you will have enough
work for much time ahead... wish you luck with the project..
I can give some of my experiences with a small PP system that I have
used and teached students in the use of it..
The component place part.:
there was a syringe to lift components and place them on the board..
the movement to the position was moving the arm with the hand..!
There was problems with taking up components.. only resistors and
transistors was easy to pick up..the surface roughness ,think,was a
problem.. When placing them and lowering the syringe to the board,the
final step was to remove the vacuum.. sometimes the component turned
a bit..If we had put paste on too many pads ,the paste had allready
gone stiff and the component did not atttach to the paste. so a
conclusion was ,not to put paste on more than ten or twenty pads
before placing the components.
The dispensing of solder paste:
there was a preasure unit that pumped the paste out..
This was the real problem.. it had ,think , 20 steps , some for
solder some for glue and each time we took out the syringe with paste
from the fridge ,it acted different. sometimes nothing came out
somtimes a whole lot came out. We never managed to get a equal
process.
throug the time, I realized ,that if the paste was not within the
date ,there was on it for "best before"..then it only made
trouble .If we had a new one, and we did not replace the tip before
next use, it would again not work good.. tried to clean the tips ,
but that did not make it work. so we had to spend a tip, to say one
pound ,each time. If I went for a coffe break , which I did very
often, it would allready have been too thick in the tip and a new tip
had to be put on..
This is the main problems with this kind of work .. I hope.. but
think it would be good for you to know what kind of problems ,you
will have to work with.
Alex