thanks dwayne, I was refering to direct to copper resist printing. a
theoretical exercise today.
I'm getting great registration for double sided toner transfer using a
light box to align. When I went to a laminator, I had problems with
the laminator rollers disturbing the alignment. Some one here
suggested using a paper carrier which works great. problem solved.
--- In Homebrew_PCBs@yahoogroups.com, Dwayne Reid <dwayner@p...> wrote:
> At 05:41 PM 9/29/2004, Phil wrote:
>
> >One thing that hasn't been mentioned in the list of problems to crack
> >is alignment for double sided resist application. I know that if you
> >take a piece of paper, print on it and then print the same thing on
> >the same side you will see some "mis-registration". I'd guess its in
> >the 10-20 mil range on my copier though I'm sure it varies with each
> >printer/copier as well as the age of the transport mechanism.
>
> I've previously mentioned (many times) the simple technique we've been
> using for more than 20 years:
>
> Take a scrap of copper clad PCB material and make an L shaped piece
with 3"
> X 4" long legs about 3/4" wide. In other words, shaped like a
carpenter's
> square.
>
> Tape one of the pieces of artwork to both arms. Flip the whole
thing over
> and very carefully line up the other piece of artwork. Tape one
edge only
> - to the longer arm. The tape is your hinge.
>
> I like to leave about 1/4" of border around all sides of the PCB.
Be sure
> to place the artwork such that you leave at least some border -
don't try
> to position the edges of the finished board right at the edge of the L
> shaped holder.
>
> Tuck your board into the pocket formed by the artwork and holder.
Process
> as normal. Be sure to feed one edge of the "L" first.
>
> The reason this works so well is that the "L" is exactly the same
thickness
> as the PCB material. Because the "L" is tucked right up to the PCB, it
> doesn't slip or move when it goes under the rollers.
>
> I've used this technique for aligning the transparencies used for
making
> boards with the photo process since the mid '70s. It also works
just fine
> when laminating directly onto the board. I routinely get boards with
> registration errors barely or not visible to the naked eye.
>
> dwayne
>
> --
> Dwayne Reid <dwayner@p...>
> Trinity Electronics Systems Ltd Edmonton, AB, CANADA
> (780) 489-3199 voice (780) 487-6397 fax
>
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