Homebrew PCBs

1) I don't think that you would get an even spread. A simple experiment would be to place a 'thin' copper wire in a clear tube and proved the current from a car battery. I believe what you will find is that  a single (hot) spot along the wire, not the entire wire, will vaperize. You would need something like:

                        /       ..................
          V+ >========o/  o=======x------------x========< V-
                                ..................
          Battery+    Switch             Tube            Battery    
       
          Thin Wire   ----------
          Heavy Wire  ==========

2)  You would need to do this in a non-oxygen/vacuum environment to prevent the copper from oxidizing.

HughAW 

--- In Homebrew_PCBs@yahoogroups.com, Branko Badrljica <brankob@...> wrote:
>
> AFAICS, main problem is hole metalisation.
> 
> Couldn't this be achieved by pure force- by running excessive current 
> through thin copper wire, which would vaporize and spurt and resolidify 
> on the via/pad walls ?
> 
> Al it would be needed is CNC with special head- wire feeder ( like the 
> one on MIG welder ) that would push the wire through each hole into 
> copper plate on the other side...
> 
> Branko
> 
> 
> 
> 
> Na 20. 07. 2010 01:33, ae5ew je pisal:
> >
> > Thanks. Charles AE5EW
> >
> > --- In Homebrew_PCBs@yahoogroups.com 
> > <mailto:Homebrew_PCBs%40yahoogroups.com>, Hugh Weinrich <hughaw@> 
> > wrote:
> > >
> > > As a designer and user PCB's in the 16-20 layer area,
> > > I would advise that once you leave the 2-layer design, and move 
> > to a 4-layer design;
> > > the complications of layer alignment & plated through holes 
> > justifies paying the 'professionals' their due.
> > > Â
> > > Four layer PCB's can be aquired for as little as 100$ for four 
> > 3.8in x 2.5in boards.
> > > see  http://www.expresspcb.com/ExpressPCBHtm/Specs.htm
> > >
> > >   As for How is a PCB Made ? see: 
> > Â www.instct.org/secure/downloads/HowIsAPCBMadeICT_V5.pdf
> > > slides 1-31 give a detailed explaniton of how this is done 
> > professionally
> > > Â
> > > Â
> > > Â HughAW
> > >
> > > --- On Mon, 7/19/10, ae5ew <ae5ew.us@> wrote:
> > >
> > >
> > > From: ae5ew <ae5ew.us@>
> > > Subject: [Homebrew_PCBs] Re: Multi-Layer PCBs
> > > To: Homebrew_PCBs@yahoogroups.com 
> > <mailto:Homebrew_PCBs%40yahoogroups.com>
> > > Date: Monday, July 19, 2010, 5:17 AM
> > >
> > >
> > > Â
> > >
> > >
> > >
> > > I'm not considering doing such a thing. Curious to understand how a 
> > reliable connection is assured in such a PCB. My experience as a 
> > technician has exposed me to some through-hole contacts on 2-layer 
> > PCBs can sometimes be a problem. Some soldering can usually correct 
> > that. Vias must be reliable for the PCB to be of use. Charles AE5EW
> > >
> > > --- In Homebrew_PCBs@yahoogroups.com 
> > <mailto:Homebrew_PCBs%40yahoogroups.com>, Dylan Smith <dyls@> wrote:
> > > >
> > > > On Mon, Jul 19, 2010 at 11:56:48AM -0000, ae5ew wrote:
> > > > > Ok. I admit I'm ignorant when it comes to this subject. How is 
> > an IC
> > > > > lead connected to say layer 8 on a 16 layer PCB.
> > > >
> > > > Via a via :-)
> > > >
> > > > I presume you're talking about through hole components, in which case
> > > > the via that forms the hole the IC pin goes through. For SMD, a 
> > via must
> > > > be drilled.
> > > >
> > > > On a commercially made board this via is through plated and makes
> > > > contact with the tracks in the inner layer that you have connected to
> > > > it. Some brave souls homebrew 4 layer boards, there are various
> > > > strategies for making contact to inner layers in absence of 
> > through hole
> > > > plating (I presume the hole on the top layer is a little larger so 
> > that
> > > > a wire can be soldered to both the inner layer and outer layer to 
> > make
> > > > the connection).
> > > >
> > > > For me a multi layer board normally means fine pitch SMD (already
> > > > increases the difficulty level in home making a PCB) as well as multi
> > > > layers, so I just use a commercial board house since two lots of
> > > > difficult tasks goes from being a fun challenge to frustration! 
> > (If push
> > > > came to shove, I'd consider a 4 layer board where the inner layers 
> > were
> > > > power and ground planes).
> > > >
> > >
> > >
> > >
> > >
> > >
> > >
> > >
> > >
> > > [Non-text portions of this message have been removed]
> > >
> >
> > 
> 
> 
> 
> [Non-text portions of this message have been removed]
>