Today was the first chance I've had to try out the new laminator and
vacuum stuff. I printed a 5-mil spiral pattern for testing.
Laminator: it comes up to temp pretty quickly (<1min) but I let it
warm up for 30 minutes to make sure the insides of the rollers were
warm too. At 240F it was running 4 sec on, 27 sec off - I think it
has plenty of range beyond the 320F it was factory-configured for.
This is a GBC 9" with my digital temperature control.
The film stuck after lamination. Even now I can't scratch it off with
my fingernail. However, it didn't solve the problems of air bubbles.
I still need to practice getting the film onto the pcb without
bubbles; a better lamination won't help otherwise. I tried exposing
the bubbles anyway to see if they'd re-laminate after developing, but
the film that was bubbled was also distorted by the heat - apparently
it needs the thermal mass and/or smooth surface of the pcb else it
gets all wrinkly and won't take an exposure properly.
One option is to put paper (or better, something lint-free) between
the film and pcb, and hold it back as the laminator feeds so that the
film and pcb come together right at the rollers.
The vacuum system worked like a charm, though. Wherever the
lamination was good, the traces were good, with only a 1 mil variation
(due to the printer's precision; I've posted about this before). I
think I need to cut down my exposure some, though, as I'm getting more
bridging than breaking. Time to re-calibrate. I've seen sites say to
use a shorter exposure for finer lines, too.
Microscope photos here, all 200x:
http://www.delorie.com/pcb/djspirals/I made the mistake of re-laminating afterwards with paper over the pcb
to keep it from sticking to the rollers. It stuck to the paper. I
was able to peel the paper off without damaging the film too much, but
next time I'm saving the poly film that I peel off ;-)
I tried wet-laminating the second pcb but it appears to also have
bubbles in it. I might need to do the old squeegie method with the
heat gun, and laminate afterwards just to ensure adhesion.
I did think about using a vacuum to do the lamination. I came up with
this plan:
top plate
air gap
flexible vacuum film - mylar, poly, whatever
UV film - stuck to vacuum film (static?)
air gap
PCB goes here
Lower plate - heating plate, smooth top.
What you do is vacuum both air gaps to as near perfect as you can get,
then release the vacuum in the top gap - the mylar will press the film
against the pcb, with no air bubbles because there's no air. The
pressure holds the film flat against the PCB. Now heat up the lower
plate to 240F to laminate it. Cool, release vacuum. Perfect
lamination?