Homebrew PCBs

On Sun, 2009-06-14 at 22:49 -0400, DJ Delorie wrote:

> Between the software to print the film and the vaccum to hold it
> against the board, I don't think the exposure is the problem. I still
> need to reliably get the film on the blank board (no bubbles), and
> figure out developing and etching methods that "always work" without
> under- or over- developing or etching.
> 

You complained earlier about this, the dry film from mg chemicals behave
different than the riston? 
But my big question is, how homebrews that do dry film without the
complete dry film roll properly fitted in the laminator, laminate the
dry film?   

I have tried to use just a piece and stretch it on the board my hand
before pass in the hot roll but I give up. Seems impossible to stretch
it properly without getting air bubbles. The professional laminators
have 3 little things that make this done right.

The only way i know to improve this is Adam Seychell 'wet lamination'
technique, the best thing in his descriptions is not the water but the
really intelligent way he laminate the dry film using a acrylic piece
rubber ended and the water surface tension. Of course that after waiting
some hours the water promotes a very good adhesion of the dry film in
copper but that's not the point.

In dry maybe laminate 2-3cm (ok a inch) of dry film making it stuck in
one end under the hot roll. Stoping the laminator and pull and stretch
the dry film other end in a 45� angle and start the laminator again it
can simulate how good laminators work. But you have to disassemble your
laminator making 90� of the roll exposed, to contact with dry film
before lamination (while stretching).

How do you do it?