Homebrew PCBs

No view camera for my work, just direct contact printing.  When I left
college and went into the electronics business, then there were rubyliths
(red cellophane image on a heavy mylar base) and the view camera was a room.
The rubylith was hung against a wall-sized light board and the camera was
mounted in an opposite wall.  The reduction of size was about 20:1, but the
whole process was essentially the same to get a master image.  That was
stepped down again 10:1 and step and repeated for a whole wafer full of
images used to make integrated circuits.  Mind you that was mid to late
1970's.  The process has changed a lot since then.

 

From: Homebrew_PCBs@yahoogroups.com [mailto:Homebrew_PCBs@yahoogroups.com] 
Sent: Tuesday, April 12, 2016 6:30 PM
To: Homebrew_PCBs@yahoogroups.com
Subject: Re: [Homebrew_PCBs] images for photoresist

 

  

On Tue, 12 Apr 2016 18:20:56 -0700, you wrote:

>I did a bit of this in my college days. We used orthographic film
>(Kodalith, I think) that was not sensitive to reds and had very high
>contrast. 

It was kodalith. It may no longer be available. You had a two part
developer that was used to give you that almost step contrast. If you
developed it in Dektol it would give you a gray scale.

>It was fairly easy to use for me and give great results. I made
>contact prints from mylars taped with Bishop tapes and pad layouts. I used
>it under a ruby light with a carbon filament. (Something my Dad had in his
>basement photo area, along with an old enlarger and developing trays.) Ahh!
>The good old days.

You forgot the 8x10 view camera....

This gave you a negative, and you had to use that with something like
Kodak KPR... nasty stuff.

Harvey

>
> 
>
>Andy
>
> 
>
>From: Homebrew_PCBs@yahoogroups.com [mailto:Homebrew_PCBs@yahoogroups.com] 
>Sent: Tuesday, April 12, 2016 4:23 PM
>To: Homebrew_PCBs@yahoogroups.com
>Subject: RE: [Homebrew_PCBs] images for photoresist
>
> 
>
> 
>
>That is simple to develop.i haven't done it in a while but it was d76
>developer , stop bath and fixer . you have to work in total dark until the
>fixer. If the size is 8 by 10 you could put it in a photo processing drum
>and let a motor do it for you. You would just need to drain the chemicals
at
>the proper time.
>
>A friend of mine used to do it with lithograph film . I don't think it was
>as touchy and it could be handled under a yellow light if I recall.
>
> 
>
>From: Homebrew_PCBs@yahoogroups.com [mailto:Homebrew!
_PCBs@yahoogroups.com]
>
>Sent: Tuesday, April 12, 2016 5:24 PM
>To: Homebrew_PCBs@yahoogroups.com
>Subject: Re: [Homebrew_PCBs] images for photoresist
>
> 
>
> 
>
>On Tue, 12 Apr 2016 17:13:31 -0400, you wrote:
>
>>I'm using laser transparencies for photoresist boards and I would like to
>>test a real photographic film image. I understand real film has solid
black
>>this is excellent at blocking light. Can anyone suggest a type of place
>>that can do photonegatives from a .jpg or .bmp? Can a CVS or Riteaid do
>>this? 
>
>You want a professional place, one that does drawings, engineering
>prints, and the like. They're likely to have the ability to make the
>image. Photolithographers, for instance. Riteaid or CVS barely know
>how t! o develop Tri-x Pan.
>
>Harvey
>
>>
>>Jeff
>
>