Homebrew PCBs

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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