Homebrew PCBs

I just find a way to solve the print geometry problem. Now I'm going to test blind alignment with needles and holes in the PCB of the same diameter.

--- On Sun, 7/6/08, Philip Pemberton <ygroups@...> wrote:
From: Philip Pemberton <ygroups@...>
Subject: Re: [Homebrew_PCBs] double sided PCB, accuracy
To: Homebrew_PCBs@yahoogroups.com
Date: Sunday, July 6, 2008, 7:45 AM










    
            Bertho Boman wrote:

> Why blind alignment?  Crank up enough backlight and you should be able to

> see through the paper.



Perhaps a strobe light would be powerful enough. Assuming you could get used 

to the flickering :)



But seriously, what about this --



1 piece of FR4, 1.6mm (assuming that's what you're using to make the PCBs). 

Remove the copper, either by etching or sanding. Cut it into four 2"x0.5" strips.



Drill a tiny - as in roughly the size of the needle - hole in each corner, 

about a quarter inch in from the top and left edges. Do the same thing for all 

four strips.



Push four thin needles into the holes. Ideally these should push in and fit 

tightly. Also put some double-sided tape on the FR4. Both sides :)



Now print your pattern with alignment holes ~2x0.5" away from the corners. 

Take one sheet of paper and push it onto the needles. Check alignment and 

remove the tape from each piece of FR4 in turn. Stick them down. Now put your 

PCB in the middle and do the same for the other side, align as before, stick 

down and remove the needles.



Iron the board and cross your fingers...



I'm still working on finding a decent TT paper that's still in production. 

Seems HP Everyday doesn't work any more... Still, it works in the inkjet (a 

rebuilt Epson C86 loaded with dye based ink) so it's not a total waste...



-- 

Phil.

ygroups@philpem. me.uk

http://www.philpem. me.uk/


      

    
    
	
	 
	
	








	


	
	


      

[Non-text portions of this message have been removed]