Homebrew PCBs

On Tue, Nov 25, 2008 at 7:28 AM, lcdpublishing <lcdpublishing@...>wrote:

>   Josh,
>
> I feel your pain! I too am working with this stuff, I am on my second roll
> now. Some boards
> turn out perfect, others, not so good.
>
> I have not found a reliable method of applying the film without bubbles. I
> am using a
> laminator with two heat settings, same results on both settings. I have not
> yet tried running
> the board through the laminator BEFORE it heats up though. I suspect this
> may help in
> getting the bubbles out before the bonding occurs.
>

Wetting the board and then letting the resist "wick" onto the board,
applying light pressure with a roller or a credit card to move the excess
water to the leading edge is very important to avoid too much water in
places or bubbles. Make sure you leave a quarter-inch or more of overhang
when applying the resist.  You want a fair amount of water on the board so
it sucks the resist onto the board and makes bubbles impossible (or easily
eliminated since there's a thin layer of water between the board and the
resist).  Too little water makes the resist instantly stick to the board
which is bad since it can trap bubbles and doesn't allow movement to
properly center the resist.  Once you've applied and centered the resist use
increasing pressure to force out the excess water.  I have a laminator with
an (added) off/on switch for the heat which works perfectly to apply
uniform, strong pressure to squeeze out the excess water.  I first trim the
resist with scissors so it has very little overhang, run it through the
laminator a couple times, and then let the laminator heat up to around
150-180F for the final run through.  Let the board sit for an hour or so
afterwards to help the water become completely absorbed or it won't be very
sensitive to UV.

Hope this helps-
Larry


>
>
> If I don't get this worked out soon, I am going to abandon the film and
> just buy pre-coated
> boards. In the end, it is probably going to be cheaper provided you get
> better and more
> consistent results.
>
> Sorry I couldn't be of more help.
>
> Chris
>
> 
>


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