Homebrew PCBs

idaho_huckleberry wrote:

> I drilled the hole with a regular through the board IC pin sized drill 
> bit (sorry, I an away from home and don't have the drill size handy), 
> then used the pen to squeeze some of the silver ink into the hole, 
> making sure that it pushed through to the other side. The donut was 
> just getting the silver ink on the surface pad to make sure there was a 
> good connection from the pad to the silver in the hole, then on to the 
> pad on the opposite side.

   Still sounds like a bit of work though not too bad.

> 
> I have not been able to try soldering on it yet to see if it will take 
> solder, though the instructions on the solder pen indicate that it can 
> be soldered to if the board is baked to cure the silver in place.
> 
> I looked into the comercial plating through the holes once and decided 
> that was not the way to go if one only needed to make a few boards now 
> and then. The information I had indicated that there was some sort of 
> Paladium coating that needed to be applied to the holes, then several 
> other plating steps that I deamed were beyond the reach of my home brew 
> budget/capability.
> 

   It is a lot of hassle and work for light or medium work.

   Thinking about it again, I see that it isn't the soldering that is the 
problem, but the locating and cutting and crimping the wires.  Soldering both 
sides is easy enough after they're in place.

   And that part could easily be automated.  A small tube just above the board 
with a stepper feeding the wire through the tube.  Say 30 gauge wire wrap wire 
with no insulation.  Have the holes just barely larger than the wire, so they 
don't need much bent over to hold it in.  Locate the hole, feed just enough wire 
to go through with about 1/16th inch extra, move the board over slightly to the 
bending blocks to hold the wire in, cut the wire, move more to finish the 
bending, then repeat.  A stationary wire feed/bending system and moving the 
board X and Y and this would be a breeze for a CNC setup.  Put in a stationary 
vertical drill and you can do the holes too.  Thin wire and you can get by with 
very little knife power, which is good since it must be thin and right at the board.

   For doing vias and drilling it might be worth making, and much simpler for 
low volume than trying to do PTH..  Same aluminum angle I use for CNC support 
would work great for bending/guide pieces, and the wire feed and knife would be 
easy.

Alan