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]
>