Homebrew PCBs

On Mon, 23 Mar 2009 14:13:13 +1100, you wrote:



I'd be tempted to do the following:

1) use a piece of vinyl (upholstery type) for the bottom.
2) make an odd older out of scraps of PC board, same thickness as your
board.  Air channels as needed, plenum or whatever for a cover with
grooves in it for vacuum.
3) upper layer is more vinyl, or plastic.  glass could be used for the
bottom as well.
4) lights on both sides.

Vacuum does not have to be extreme.  1/10 atmosphere is still 1.47
pounds per square inch pressure on the board.  Ought to be enough.

I've mad a vacuum frame for one sided work out of shelving with a 1/4
inch hole matrix (1 inch spacing), holes for shop vac.  Light frame on
top.  Upholstery vinyl for the cover.  Old photographic enlarger timer
for exposure.  You might find a lot of them now that digital has
"won"... (not really, but they ought to be easy to find).

Harvey


>Well, this thread that wont die gets you thinking:
>
>My first thought was:
>
>glass
>fabric
>board (incl. artwork and film)
>base
>
>to evenly remove the air between the board and the glass. But, uh, the  
>UV might not go thru the fabric so evenly ...
>
>Board and glass need to be close to the same size to prevent stress,  
>with a flexible seal around them.
>
>Then I thought, you could replace the glass with clear vinyl, which  
>will just flow around the board and not bow
>
>Then I thought, make the *bottom* vinyl and eveything is evenly  
>pressed UP onto the glass with no stresses at all, and you still get  
>that nice even glass.
>
>Then (for the less frequent exposer) why not stick the whole sandwich  
>into one of those vacuum  "space bags" you use to shrink your winter  
>clothes away with.
>
>(Myself, I think I'll keep on improving my TT skills)
>
>PG
>
>