Homebrew PCBs

Haveing just taken a shot at John for being condecending to a new 
idea, I should admit that I also think his Scratch and Etch idea is 
totally brilliant.

Has anyone ever just gone and tried this? I have done it with a 
simple plotter, a scribe in place of a pen, and a sheet of glass 
painted black. It works like a dream. My goal was to make a digital 
sun dial, not to etch PCBs, but I can't see why it wouldn't produce 
finer results than any other method.

The only trick is finding a paint that drys quickly to a hard (not 
brittle or tacky) finish so that it is completely and cleanly 
removed by the scribe. Also, the plotter may need to be a nice big 
one like my tough old HP (God rest its soul) because the scribe is 
going to drag more than a pen... probably.

Yup, I do Scratch and Etch. I've made boards that way. I use an HP plotter
(one of the larger ones). The trick is the 'paint' as you say - I use Dykem,
which is a machinists bluing agent. It's lacquer based, so dries quickly.
The tough nut is generating your artwork.

*Brian

-----Original Message-----
From: James Newton [mailto:jamesmichaelnewton@...]
Sent: Friday, November 12, 2004 6:19 PM
To: Homebrew_PCBs@yahoogroups.com
Subject: [Homebrew_PCBs] Scratch and Etch? has anyone?




Haveing just taken a shot at John for being condecending to a new 
idea, I should admit that I also think his Scratch and Etch idea is 
totally brilliant.

Has anyone ever just gone and tried this? I have done it with a 
simple plotter, a scribe in place of a pen, and a sheet of glass 
painted black. It works like a dream. My goal was to make a digital 
sun dial, not to etch PCBs, but I can't see why it wouldn't produce 
finer results than any other method.

The only trick is finding a paint that drys quickly to a hard (not 
brittle or tacky) finish so that it is completely and cleanly 
removed by the scribe. Also, the plotter may need to be a nice big 
one like my tough old HP (God rest its soul) because the scribe is 
going to drag more than a pen... probably.






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James,
      People have used layout blue used by metal workers. Make sure
you use a tip that creates enough isolation between traces. If you
don't you will have problems if you tin plate the board. (Problem
reported by Mike of this group to me on my group) 
      I found and old message on the internet from a robotics group
that used the idea a year before me so I have to credit them for being
first. I could not tell by the message if they were using a plotter or
CNC machine to scratch the board.

                                            John 


--- In Homebrew_PCBs@yahoogroups.com, "James Newton"
<jamesmichaelnewton@y...> wrote:

> 
> Haveing just taken a shot at John for being condecending to a new 
> idea, I should admit that I also think his Scratch and Etch idea is 
> totally brilliant.
> 
> Has anyone ever just gone and tried this? I have done it with a 
> simple plotter, a scribe in place of a pen, and a sheet of glass 
> painted black. It works like a dream. My goal was to make a digital 
> sun dial, not to etch PCBs, but I can't see why it wouldn't produce 
> finer results than any other method.
> 
> The only trick is finding a paint that drys quickly to a hard (not 
> brittle or tacky) finish so that it is completely and cleanly 
> removed by the scribe. Also, the plotter may need to be a nice big 
> one like my tough old HP (God rest its soul) because the scribe is 
> going to drag more than a pen... probably.

I've been looking at ways to use a router to make circuit boards.
The Eagle Package has a tool that creates a router path around
each trace.  That should work very nicely with scratch and etch.
Now, if I could just get the footprint tool to put the pads on
grid, I'd be a happy camper.

If someone can suggest a scratchable resist that's been verified
to work, I'll give it a try.  Just to be clear, I don't want
suggestions of things to try that "might work".  I want to hear
about something that's been verified to withstand FeCl by the person
making the suggestion.  I really don't care that your cousin's baby
sitter's father thinks that asphalt would be good to try... ;-)  
Life is too short.  

Thinking out loud...
Laser toner would be a good thing to try if
I could figure out how to get a thin, uniform layer.


mike

--- In Homebrew_PCBs@yahoogroups.com, "James Newton"
<jamesmichaelnewton@y...> wrote:

> 
> Haveing just taken a shot at John for being condecending to a new 
> idea, I should admit that I also think his Scratch and Etch idea is 
> totally brilliant.
> 
> Has anyone ever just gone and tried this? I have done it with a 
> simple plotter, a scribe in place of a pen, and a sheet of glass 
> painted black. It works like a dream. My goal was to make a digital 
> sun dial, not to etch PCBs, but I can't see why it wouldn't produce 
> finer results than any other method.
> 
> The only trick is finding a paint that drys quickly to a hard (not 
> brittle or tacky) finish so that it is completely and cleanly 
> removed by the scribe. Also, the plotter may need to be a nice big 
> one like my tough old HP (God rest its soul) because the scribe is 
> going to drag more than a pen... probably.

--- In Homebrew_PCBs@yahoogroups.com, "gettingalongwouldbenice"
<gettingalongwouldbenice@y...> wrote:
> 
> I've been looking at ways to use a router to make circuit boards.
> The Eagle Package has a tool that creates a router path around
> each trace.  That should work very nicely with scratch and etch.
> Now, if I could just get the footprint tool to put the pads on
> grid, I'd be a happy camper.
> 
> If someone can suggest a scratchable resist that's been verified
> to work, I'll give it a try.  Just to be clear, I don't want
> suggestions of things to try that "might work".  I want to hear
> about something that's been verified to withstand FeCl by the person
> making the suggestion.  I really don't care that your cousin's baby
> sitter's father thinks that asphalt would be good to try... ;-)  
> Life is too short.  
> 
> Thinking out loud...
> Laser toner would be a good thing to try if
> I could figure out how to get a thin, uniform layer.
> 
> 
> mike

Hmm, electrostatically charge the laser-printer toner, and then
sprinkle it across the board?  

I suppose (if you were careful not to turn the board over or 
shake it too violently) you could mount it in a flatbed plotter
and trace out the places you wanted to etch with a Q-tip.  Then,
heat the board to fuse the toner, and you're ready to etch.

Naw, it probably wouldn't work.

Dave