Homebrew PCBs

Thanks muchly Malcolm.  That makes things a lot clearer.

 

Question – did you do any silkscreening back then for parts placement?  I notice in the plans printed by Radio Electronics, they had the printouts for the copper side, but also silkscreening for the non-copper side to aid in parts placement.  I’m wondering how a home hobbyist at the time might have pulled that off, or if they did.

 

From: Homebrew_PCBs@...m [mailto:Homebrew_PCBs@yahoogroups.com] 
Sent: Tuesday, September 29, 2015 4:15 PM
To: Homebrew_PCBs@yahoogroups.com
Subject: Re: [Homebrew_PCBs] G-10 questions

 

  

Back in those days I used two methods:
Copper clad FR4 was available, but a lot of SRBP was used as it was much cheaper.
The first method was to paint, by hand, using mothers thinned nail varnish onto a carbon paper print traced from the layout printout.
There was a great negative photo resist, KPCR, made by Kodak, sadly no longer available that you exposed to ultra violet light through a negative transparency of the of the layout.
Then developed in a solvent based solution that coloured your fingers red for at least a week if you got it on them.

So you would not be cheating if you used modern pre-sensitized copper FR4 from companies such as Mega,
<http://www.megauk.com/pcb_laminates.php>
or a dry film:
<http://www.instructables.com/id/Fantastic-Double-Sided-PCBs-at-home-using-photores/>
or
<https://www.youtube.com/watch?v=cRCFGZxmob0>

Malcolm

I don't suffer from insanity I enjoy it!
Mene, mene, tekel, upharsin
The writing is on the wall.
Ha-ktovet al ha-kir

--------------------------------------------
On Tue, 9/29/15, 'Brad' unclefalter@... [Homebrew_PCBs] <Homebrew_PCBs@yahoogroups.com> wrote:

Subject: [Homebrew_PCBs] G-10 questions
To: Homebrew_PCBs@yahoogroups.com
Date: Tuesday, September 29, 2015, 11:51 PM


 









Hi guys,  I’ve been continuing to
research and amass parts for my TV Typewriter replica build.
 I have a blog of it here: http://bradhodge.ca/blog 
-- mostly working on the case right now to inspire me to
push forward, but I’ve succeeded in getting almost all of
the vintage 1973 or earlier chips I needed.  Now I’m down
to the PCBs again.
 I guess I’m still
kind of ‘green’ on this sort of thing.  Ideally, I’d
like to do my PCBs the way they would have in 1973.  But I
still don’t understand how that worked.  Don Lancaster
said the boards used were green G-10.  I found this on
ebay:  http://www.ebay.com/itm/16-Green-G-10-FR4-Sheets-032-Thick-x-28-x-7-25-G10-Material-/141719358328?hash=item20ff21cb78  I guess what I’m having trouble
with is understanding how a home PCB maker in 1973 would
have gone about getting copper onto these boards and copying
the artwork from the article.  Is there any really good,
baby-steps reading out there?  I just want to understand
the original process and if it is possible to replicate it
here in 2015.  I sort of understand the idea behind photo
lithography.. I’m just not understanding how copper ends
up on board, etc.  Much appreciated!  BRad     









#yiv0643880995 #yiv0643880995 --