Homebrew PCBs

--- In Homebrew_PCBs@yahoogroups.com, "joshdewinter" 
>   Now I have another question...just as I was about to submit my 
> circuits to a board house...I need a method to align my top and 
> bottom sides.  Is there anything anyone does that works especially 
> well?  I have looked through the messages from the group and have 
> heard of people taping both top and bottom on, and running them 
> through at the same time.  That sounds like it would work, but how 
do 
> you align them accurately?


I use the TT method and a laminator; although I haven't had the heat 
problems you had with my stock laminator.  It might have to do with 
the type of toner you are using.  I know a guy accross town that has 
been doing 1 sided boards OK with the same laminator (w/o modifying 
the heat element btw).  What kind of clad are you using? He does .5 - 
1 oz 1/16" stock in his --although the rigid roller transport does 
make a bit of noise doing so.

Most of the homebrew boards I do are double sided.  I print the top 
and bottom, (top mirrored) onto magazine paper making a few alignment 
crosses outside of the board boundary lines.  Under a bright desk 
lamp I align the crosses of the two pages with the toner sides in.  I 
use a glue stick and bind one of the edges to create an envelope.  
Sandwich the board into the envelope and insert the bound edge side 
in first into the laminator.  Make 2-3 passes in the same direction 
until the toner "tacks". After that you can clip off the bound edge 
and rotate and flip the board for a few passes until the toner has 
fastened to the copper clad.

The sandwich works pretty well on some pretty tight via pitches.  The 
possiblity of the skew from the bound edge justifying to the top or 
bottom turns out to be a non-event.  The rollers tend to align the 
binding with the center of the board when initially fed --as long as 
you insert the bound edge in first and fairly perpendicular to the 
board edge.

I have a write up on this in case you missed it in the TT links 
section...
http://myweb.cableone.net/wheedal/pcb.htm 

-Dal
(Pocatello, ID)