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Hi Bill,
I've made a few boards, none as big as these S-100 boards but the designing concepts are the same but with less head aches. There is a whole industry of experts that build circuit boards and lots of jargon in that field. You should know most of the words already. Traces, Pads, Via's, solder mask, silk screen layer, component outlines or foot prints, thermal relief pads. But when I was building some of my first commercial boards, I learned some new terms: -Gerber files (these are the standard format for circuit boards, they are a vectored graphics type file like autocad) -Drill file (a text file that dictates the location and size of holes to be drilled) -12/12 rule. that is, 0.012" trace thickness with 0.012" spacing between traces. I think high density boards go as low as 8/8. -Net list. The list of all pins that must be electrically connected to each other. eg, the net list for the electrical ground on a board might go something like this, Mountinghole1+Mountinghole2+C1(pin2)+IC1(pin7)+IC2(pin7)+IC3(pin7)+R1(pin2)+R2(pin2)....etc The Net List is created by your schematic program and is useful to ensure you haven't missed any traces on your PCB layout program. The first thing you must do is define your PCB size and shape, then place your components on the board. Arrange them in a practical manner, ie the RS-232 chip next to the DB connector, etc. The spacing and how to arrange them can't be defined by rules, but only by experience. I usually move at least 1/2 of the components before I'm finished. I'm certain others here are better at it than me but I'll be surprised if they don't move any parts after the initial "guessing". I've done some boards through http://www.expresspcb.com/ they have free software that works very nicely. Personally, I don't use any auto trace routing, so I manually optimize my traces by hand. I hope this helps answer some of your questions, even though I'm not an expert. Regards, Josh From: billy...@comcast.net To: n8vem...@googlegroups.com Subject: Re: [N8VEM-S100:1465] S-100 board reorders Date: Sun, 24 Feb 2013 14:20:39 -0500 I have a slightly off topic question for
you.
I have never made a PC board or trace routed or
optimized a board.
Could you explain the process?
How do you start with chip placement? What software
do you use? Is this a professional version or is it something a hobbyist could
get freely. What kind of computer is the board designed on, is it
vintage?
How long does optimization take to complete? It
seems like it takes weeks or months to complete. Is this run on a modern
computer? Is optimization different that trace routing or is it just the final
step of the process?
I know that's a lot of questions but you did ask
"Questions?".
Thanks for all your work.
Bill
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