Homebrew PCBs

You can also coat the board with layout blue and then put a
spring loaded scribe in the mill and have it scratch out the isolation
then put the board in acid. Make sure the scratch mark is wide enough
in a few areas so you can tell the board is done. Remember the mill
can also drill your holes. A copier won't do that. If you do surface
mount boards then TT is the best overall method.



--- In Homebrew_PCBs@yahoogroups.com, "lcdpublishing"
<lcdpublishing@y...> wrote:
>
> I just thought of something else regarding efficiency. Even though I 
> don't make a lot of circuit boards, I have been etching two, and 
> even, three boards at the same time.  This is very efficient and is 
> only limitted by the size of the etching tank.  
> 
> Having been in shops of one type or another my entire adult life, I 
> probably have been exposed to more toxins than I care to think 
> about. So, fear of: acids, projectiles, and dust isn't an issue for 
> me - been there done that sort of thing I guess.  Frankly, I am much 
> more fearful of the dumb girl in the car in front of me talking on 
> the cell phone and not paying attention to driving ;-(
> 
> A while ago I did read that article you mentioned, and you are 
> right, they were not very positive at all about milling.  
> 
> Hmmm, makes me think of another possiblity though - laser etching?  
> I know there are lasers that can focus their "cutting depth" which 
> might allow for cutting through the copper and not the substrate.  I 
> would have to guess that this sort of laser would require a bit of 
> power though.  
> 
> Chris
> 
> 
> 
> --- In Homebrew_PCBs@yahoogroups.com, "Stefan Trethan" 
> <stefan_trethan@g...> wrote:
> >
> > Mechanically milling PCBs is inferior. full stop.
> > 
> > It's done by people who have a unreasonable aversion to acids (and 
> no fear  
> > of high-speed debris projectiles or glassfiber dust strangely).
> > There's no real advantage.
> > You can read the paper on milling vs. etching by bungard (who 
> sell  
> > machines for both) and you'll see not even they like milling.
> > 
> > ST
> > 
> > 
> > 
> > On Thu, 08 Dec 2005 23:23:28 +0100, lcdpublishing  
> > <lcdpublishing@y...> wrote:
> > 
> > > Okay, as you all know I am far from experienced with PCB 
> making.  I
> > >
> > > have gone through a variety of trials with the toner transfer 
> method
> > >
> > > and can appreciate it.  I can somewhat see it's limitations with
> > >
> > > regard to how small of a trace I could do using this process.
> > >
> > > However, if I ever need more detail, I could do the photoresist
> > >
> > > process.  The chemicals work good and efficient, all around, 
> etching
> > >
> > > works very good.
> > >
> > >
> > > Now about 6 months ago, I was wanting to do isolation milling as 
> I
> > >
> > > believed it to be better.  However, I am pretty much now in the
> > >
> > > belief trying isolation milling will not show any advantages over
> > >
> > > what I am doing now.  I seriously doubt it would be faster than
> > >
> > > chemical etching.  I don't think the tool bits would last very 
> long,
> > >
> > > so I would guess that the tooling costs would negate the costs of
> > >
> > > the chemicals. Even though you would be cutting with a very small
> > >
> > > diameter pointed tool, I don't think you could get better results
> > >
> > > (finer pitches and traces) using a milling process.
> > >
> > >
> > > Is there something that I am not seeing in that process that 
> would
> > >
> > > give it advantages over chemical etching?
> > >
> > >
> > > Thanks guys
> > >
> > >
> > > Chris
> >
>