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).
>
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