On Feb 28, 2009, at 11:21 AM, Stuart Brorson wrote: > Hi -- > >> How often does the need for single-sided boards arise? > > The question about single-sided boards is interesting, but the > answer depends upon how you intend to fabricate your boards. > > If you're sending the boards to a PCB manufacturer, then the raw > material they use is fiberglass clad with copper on both sides. In > this case, it's senseless to ask for a single-sided board to save > costs -- they start with a double-sided board in any case.
To be fair, this is true when making few boards. AKA less than a LOT Your PCB manufacture would order single sided stock if you were making say 10,000 boards plus. Or if you were dealing with a manufacture that dealt a lot with single sided boards. TV manufactures and boom box makers use these tricks, but they also do things like use FR2 http://en.wikipedia.org/wiki/FR-2 The quick turn PCB houses online, usually don't run single sided for small jobs, as they panelize your board with others, that are most likely double sided. > > > If you're making the PCBs at home, starting with single-sided > fiberglass from e.g. Radio Shack, then it's totally sensible to make > single sided boards. In this case, just throw away the back side > Gerber file. > >> this kind of >> cosmetics with gerber files is an additional error-prone manual step. >> Has it been considered to make this an option that is supported by >> pcb? > > I agree that it tends to trip up newbies. However, there's one Gerber > file per (metal) layer, so you can always discard the back side file > without any problems. > > More to the point: the Gerber, and the related drill file > formats are pretty stupid. They don't carry any top-level > information about your design. A particular Gerber file knows only > about its own layer, and knows nothing about any other layer. The > Gerber files have no concept of "stack-up" (i.e. what order the layers > are supposed to be stacked in). The drill file only contains > information about what drill diameters to use, and where to put the > holes. The remaining information, like stack-up, plated > vs. non-plated holes, how thick your copper layer should be, how thick > your FR-4 should be, desired manufacturing tolerances, etc., are all > told to your PCB manufacturer using "fab notes" (i.e. a > human-readable text file) and a "fab drawing" (a drawing of the board, > stack-up, and other graphical info). > > Finally, one of the projects slated for work under the Linux Fund's > PCB project is to update PCB's handling of layers. Things like the > ability to easily deal with single sided boards from inside of PCB > are part of the work to be funded by the Linux Fund. I'll just remind > everybody that they can make this work happen sooner by making a > donation! > > http://www.linuxfund.org/projects/pcb/ Thanks for the reminder, I just chipped in some. > > > HTH, > > Stuart > > > _______________________________________________ > geda-user mailing list > geda-user@moria.seul.org > http://www.seul.org/cgi-bin/mailman/listinfo/geda-user _______________________________________________ geda-user mailing list geda-user@moria.seul.org http://www.seul.org/cgi-bin/mailman/listinfo/geda-user