Homebrew PCBs

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. I'm only using this as an example. The same thing with connecting to layer 2 of a four layer PCB. The top and bottom layers are straight forward. A 16 layer board is built one layer at a time (etching)? I have never worked with anythng other than 2 layer PCBs as far as installing/removing components. Modern computers use multilayer PCBs. Any guidance would be appreciated. TIA  Charles  AE5EW

Is anyone routinely making their own 4-layer PCBs. Charles  AE5EW

--- In Homebrew_PCBs@yahoogroups.com, "ae5ew" <ae5ew.us@...> 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. I'm only using this as an example. The same thing with connecting to layer 2 of a four layer PCB. The top and bottom layers are straight forward. A 16 layer board is built one layer at a time (etching)? I have never worked with anythng other than 2 layer PCBs as far as installing/removing components. Modern computers use multilayer PCBs. Any guidance would be appreciated. TIA  Charles  AE5EW
>

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).

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, 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).
>

ae5ew wrote: 
> How is an IC lead connected to say layer 8 on a 16 layer PCB. A 16
> layer board is built one layer at a time (etching)? Any guidance would
> be appreciated. 


Difficult to see is how the layer stack is interconnected. Some images
of vias, blind vias, buried vias, filled vias from a quick search
http://www.pcb007.com/pages/zone.cgi?a=48518&_pf_=1

Build process varies and is complex. See these two books:
http://books.google.pt/books?id=m8sJBIMtETgC&pg=PA414&lpg=PA414
http://books.google.pt/books?id=g9Q8RekeKaAC&pg=PA16&lpg=PA16

A easy way to see it, is a manufactor start with a core double layer
board, it's imaged and etched and goes to the stack build by over laying
a not cured resin layer and a copper foil on each side and hot pressed.
It became a two layer board again and is re-processed. If you wish
buried vias the board is drilled and plated each time. But there are
stacks of double layers drilled and pressed one time only.
The plating process to deposit copper on the hole wall, is a resin
activation chemical steps followed by a modified copper plating bath
that plates same copper amount on low resistance copper as well
activated resin. (Or old electroless process)

http://www.hottconsultants.com/tips.html has a section on how and why of
multi-layer board construction. The layers are generally not added for the
sake of making it easier to connect parts; rather for EMI reduction and
higher frequency circuits. The "PCB Stackup" articles should give you some
pointers on the how and why.

As you appear to be a ham- you may also find "Dipoles for Dummies"
enlightening for both the hobby and PCB design in general.

73
Bill N4BKT

On Mon, Jul 19, 2010 at 8:17 AM, ae5ew <ae5ew.us@...> wrote:

>
>
> 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 <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]

On Mon, 19 Jul 2010 12:02:48 -0000, you wrote:

>Is anyone routinely making their own 4-layer PCBs. Charles  AE5EW

No.  The best way I have heard to do this is to overdrill the blind
vias on the top and bottom layers, then wire jumper to the inner
layers.  Standard vias do not connect the two middle layers, or to the
two middle layers, but only top to bottom.  This avoids the plated
through holes.

I have yet to design and implement a board like this, though.  Still
theory.

Harvey

>
>--- In Homebrew_PCBs@yahoogroups.com, "ae5ew" <ae5ew.us@...> 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. I'm only using this as an example. The same thing with connecting to layer 2 of a four layer PCB. The top and bottom layers are straight forward. A 16 layer board is built one layer at a time (etching)? I have never worked with anythng other than 2 layer PCBs as far as installing/removing components. Modern computers use multilayer PCBs. Any guidance would be appreciated. TIA  Charles  AE5EW
>>
>
>
>
>
>------------------------------------
>
>Be sure to visit the group home and check for new Links, Files, and Photos:
>http://groups.yahoo.com/group/Homebrew_PCBsYahoo! Groups Links
>
>
>

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.
 
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:  www.instct.org/secure/downloads/HowIsAPCBMadeICT_V5.pdf
slides 1-31 give a detailed explaniton of how this is done professionally
 
 
 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
Date: Monday, July 19, 2010, 5:17 AM


  



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, 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]

I've done some home-brew 4-layer boards, but without plated-through 
holes.  It's tricky, you need to design for it, leaving plenty of room 
on the outside layers where you want to connect to an inner layer, so 
you can drill a hole big enough to stick your soldering iron down into. 
  It's not the most reliable results, either, but for some throw-away 
boards it's the best solution.

For professional boards, fabrication involves at least one drill step 
that drills all the way through all the layers, then a chemical bath 
removes the smeared epoxy from the drill bit, exposing the edges of the 
copper for the inner layers.  When you then electroplate it, it makes 
electrical connections between the layers.

Thanks.  Charles  AE5EW

--- In Homebrew_PCBs@yahoogroups.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:  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
> 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, 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]
>

This was an interesting read.
www.instct.org/secure/downloads/HowIsAPCBMadeICT_V5.pdf
It does a good job answering my question.
Charles  AE5EW

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]

.... another approach:

As I had mentioned,the SMDs and ICs component sizes that I am using are so
small,I have abandoned trying to make very small, multi-layer, fine trace boards
at home.

I now build all my very small and extremely dense prototypes with-out a "PCB" in
one or two days completed!: 
http://tech.groups.yahoo.com/group/Homebrew_PCBs/message/26052
http://groups.yahoo.com/group/Homebrew_PCBs/photos/album/2086759579/pic/list


--- In Homebrew_PCBs@yahoogroups.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:  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
> 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, 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]
>

With the exception of multilayer bit, I don't see anything special on 
your pictures.

Those tracks are somewhere around 8-10 mils, which is easily achievable 
at home, with a bit of practice and equipment tuning, ofcourse.




Na 20. 07. 2010 02:05, Richard je pisal:
>
> .... another approach:
>
> As I had mentioned,the SMDs and ICs component sizes that I am using are so
> small,I have abandoned trying to make very small, multi-layer, fine 
> trace boards
> at home.
>
> I now build all my very small and extremely dense prototypes with-out 
> a "PCB" in
> one or two days completed!:
> http://tech.groups.yahoo.com/group/Homebrew_PCBs/message/26052
> http://groups.yahoo.com/group/Homebrew_PCBs/photos/album/2086759579/pic/list
>
> --- 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]

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]
>

Hello from a new member, just a small thanks to the arbitrator for having me in your group. On the matter of plating through holes, I recently read an article on the use of conductive ink (Stabillo is the supplier, I think). The board has the TPH and vias's drilled first, then a thin coat of ink is squeegeed on both sides. Using a vacuum cleaner with a nozzle attachment,carefully remove any surplus ink from the holes and allowed to dry. The board is the immersed in a weak solution of acid (sulfuric ?) with a lump of copper and connected to a 12Volt current limited power supply to allow the electro-plating process to evolve, lining the holes with a layer of copper. Will try and find the article and post the link, chester



      

[Non-text portions of this message have been removed]

--- In Homebrew_PCBs@yahoogroups.com, "ae5ew" <ae5ew.us@...> wrote:
>
> 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
> 


I've contemplated trying just to see if I could do it, my thought was to use solder paste to interconnect traces on the layers and cook the board on a hot plate. I don't really think it's worth the hassle though, if I ever needed a multilayer board I'd just have it professionally made.

--- In Homebrew_PCBs@yahoogroups.com, Branko Badrljica <brankob@...> wrote:
>
> With the exception of multilayer bit, I don't see anything special on 
> your pictures.
> 
> Those tracks are somewhere around 8-10 mils, which is easily achievable 
> at home, with a bit of practice and equipment tuning, ofcourse.
> 


I regularly and dependably do 10 mil tracks with 603 and 805 size components. I can do SSOP ICs but that's pushing it and generally requires a bit of hand cleanup to remove shorts between adjacent pads. It's difficult to make such closely spaced pads, I believe the toner squishes out a bit and makes them wider.

The solder will bead up rather than forming a thin layer across the layers. Or did you mean for the holes to stay filled with solder?

You'll still need to do the acid bath to clean off the smeared epoxy in the drilled holes.

Steve Greenfield AE7HD

--- In Homebrew_PCBs@yahoogroups.com, "James" <jamesrsweet@...> wrote:

>
> 
> I've contemplated trying just to see if I could do it, my thought was to use solder paste to interconnect traces on the layers and cook the board on a hot plate. I don't really think it's worth the hassle though, if I ever needed a multilayer board I'd just have it professionally made.
>