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Re: Homemade PCBs!
Original poster: "john cooper" <tesla-at-tesla-coil-dot-com>
FWIW - boards we used to get in from China were typically made with layers
of rice paper. Stop laughing, I'm serious, really.
---------- Original Message ----------------------------------
From: "Tesla list" <tesla-at-pupman-dot-com>
Date: Wed, 28 Apr 2004 21:55:13 -0600
>Original poster: "Jim Mitchell" <Electrontube-at-sbcglobal-dot-net>
>
>There can be more then two sides! Its just that the middle layer(s) is/are
>just connections and do not house any components.
>
>Regards - Jim Mitchell
>----- Original Message -----
>From: "Tesla list" <tesla-at-pupman-dot-com>
>To: <tesla-at-pupman-dot-com>
>Sent: Wednesday, April 28, 2004 7:13 PM
>Subject: Re: Homemade PCBs!
>
>
> > Original poster: Fucian-at-aol-dot-com
> >
> > In a message dated 4/28/2004 10:15:26 AM Eastern Standard Time,
> > tesla-at-pupman-dot-com writes:
> > Layers are exactly what the name says, 'layers'. Sort of a 'paper sheet'
> > which contains something. The PCB is then stacked/sandwiched together from
> > these layers.
> >
> > A typical single sided pre-UV-resist-coated DIY PCB:
> > 1 photoresist layer
> > 2 copper layer
> > 3 glue layer
> > 4 epox&fiberglass lamination layer (the "circuit board")
> >
> > If you order commercially produced single sided PCBs, typical order of
> > layers might be:
> > 1 silk screen (component names and other text printed on the PCB)
> > 2 solder mask layer (the often deepgreen protective coating you see on
> > PCBs, it helps against corrosion and prevents solder flowing onto
> > copper tracks where you don't want it)
> > 3 copper layer (this is where the signal traces are)
> > 4 glue
> > 5 epoxy&fiberglass board
> >
> > Then there are a bunch of additional "non-physical" or "info" layers that
> > are defined in the software PCB file. For example, where the automatic
> > drill should be drilling, to what dimensions the board should be cut, etc.
> >
> > You could have a try on Eagle (www.cadsoft.de) and wonder at how many
> > layers the PCB board editor contains ;-)
> >
> > If you meant what the use of multiple copper layers is -
> > oversimplified, they reduce the number of jumper wires you need. If you
> > look inside cheap TV, video or stereo sets, there's LOTS of jumper wires
> > there, a real mess. Nearly all those jumpers could be replaced with copper
> > traces on a new, added second copper layer. Much cleaner result and less
> > work, but it costs a bit more.
> >
> > OTOH if you look at your PC motherboard, there are thousands of component
> > pins that should be connected together. A single copper layer
> > obviously isn't enough, and jumper wires are a really bad idea.
> > Additionally taking into account RF layout requirements (>100MHz to
> > >10GHz signals there, needs ground and DC supply planes), you end up with
> > at least a 4-layer board. I don't know exactly where PC computer boards
> > are going nowadays, but I'd think they typically use from 8 up to 16
> > layers.
> >
> > To keep this even remotely TC related: if you build SSTC or flyback
> > boards, it is a good design practice (IMHO) to use two layers. For
> > example, one larger combined ground and power plane on the bottom layer,
> > and logic and RF signals on the top layer. That way the circuit is, for
> > one, much less susceptible to HV RF interference (e.g. more bullet-proof).
> >
> > cheers,
> > - Jan
> >
> > --
> > ****************************************************
> > Helsinki University of Technology
> > Dept. of Electrical and Communications Engineering
> > http://www.hut.fi/~jwagner/ -
> >
> > Ahhhh it is clear now! :-) I was thinking layers were copper layers...I
>was
> > thinking, " how could there be more than 2 sides to a pcb?"
> >
> > I didnt know layers were just like a part of the design...
> > Matt
> >
>
>
>