Homebrew PCBs

On Fri, 4 Jul 2008, Harvey White wrote:

> On Fri, 4 Jul 2008 09:47:55 +0100 (BST), you wrote:
>
> I've always had a conceptual problem doing it exactly this way.  I can
> see that if the joint between the two pieces of paper is exactly in
> the middle of the board thickness, every thing aligns.  If it's not,
> then one layer is offset with respect to the other.

I've never found it to be a problem. I only had bad registration on one
board I've made this way, and even then it wasn't bad enough that the
board couldn't be used. Most of the time the registration is pretty much
spot on. If you need really fine tolerances for small vias then I suspect
a piece of old board in the tape 'hinge' as you suggest would reduce the
risk of mis-registration. I use 0.8mm drill bits, so my vias tend to be
sized for that (except for things like jumper headers where I use 1.0mm
bits), with 10 mil annular rings minimum (so that'd make my largest vias
35 mils, and the smaller ones 30 mils.