I have been designing hardware a long time but unfortunately I have always outsourced my PCB work. Well I finally got caught without an ore. I'm frantically trying to learn all I can to finish a job while my main PCB guy is fighting colon cancer. I think I can pull the job off using expressPCB but it does not have gerber capability. I have also tried CadSoft but I don't understand for example the details of a wheel file. I need some sort of tutorial on the layers of a Gerber file. Appreciate your help as always, Thanks :)
Posted on 2004-03-12 22:11:29 by mrgone
A gerber file is just an ASCII text file containing start and end points of some 'apeture' sweeping across the plot. It is a legacy format from a time the plot was literally a hold (such as a square or a circle) allowing light to pass, and the hole was swept across some photographically sensative film.

Obviously today its all digital.


Each file in a gerber plot represents some sort of layer, for example a typical 2 sided board would have top metal, bottom metal, top mask, bottom mask, and a top silk screen. A drill file, being X-Y coords with hole size is also needed.

I don't know how the overall board size gets set.

One good cheap source for PCB CAD ware is CadSoft, maker of the Eagle layout editor, free for personal use, 50 bucks for commercial, and expandable. Their site lists houses that will accept Eagle files directly for board production.
Posted on 2004-03-13 03:12:58 by Ernie
Did you ever figure out how to set the board size? I've been using CadSoft and appears to do the job because I can pull up the layers with Veiwmate. Also do you know how to put components on bottom side of board? I've been building my library from smd-ipc.lbr (which only has package footprints) but they happen to be all the ones I need lol such as 0805 etc. Anyway I need to put some on back of board.

I found this:

All relevant data from the schematic file (name.sch) will be converted to a board file (name.brd). The new board is loaded automatically as an empty card with a size of 160x100mm (Light edition: 100x80mm), where the outlines are placed in such a way that the board is centered between the 50mil grid. All packages and connections are shown on the left side of the board. Supply pins are already connected (see PIN command).

If you need board outlines different to the ones that are generated by default, simply delete the respective lines and use the WIRE command to draw your own outlines into the Dimension layer. The recommended width for these lines is 0.
Posted on 2004-03-21 12:36:02 by mrgone
You use mirror command to place on bottom side. Got another question though. My guy that usually does the gerbers has a method where he can mirror the whole bottom side of board even text that lables layer so that you can line up all connections top and bottom when veiwed in "Veiwmate". That is a slick feature. I wonder how he does that? Well he uses "Orcad and converts to "PadsPCB". Wish I could do that. Sure is helpful for double checking your work.
Posted on 2004-03-22 01:42:59 by mrgone
If it's only for checking purposes, you can mirror the layers in Viewmate and print them out that way.
Just select all elements in the layer an then click on the mirror icon. Next, a window pops up where you select the center of the mirrored image. Select "Center of selected elements". That will mirror everything, without moving them.
Then you just print out the layer.
Posted on 2004-03-22 11:14:54 by VVV
I looked and looked for that feature in Veiwmate and just never hit right features. Let me try this out! :alright:
Posted on 2004-03-22 13:43:01 by mrgone
Thanks again!
Posted on 2004-03-22 13:55:30 by mrgone
The CadSoft program I'm using when I import my file to Veiwmate and set scaleing fanctor to inches it show my simple surface mount PCB as being almost 17 inches long. The guy that usually does the boards well thank God is feeling much better and will continue to work for us, his boards are exactly to scale when veiwed by Viewmate so that you know the size of the board when you view it.
Posted on 2004-03-24 00:07:26 by mrgone
If the Gerber format is RS-274-X, that should not happen. If the format is the older RS-274-D, then this is possible.

To avoid it, click on the "Options" button before you start importing. Given that you know the dimensions of the board, set the "Data format" accordingly: 1 digit left of decimal (I don't think your board is larger than 9.999 in. in any direction).
This will ensure the dimensions are imported correctly.

When printing, set the Scale to 1 (check the "By factor" radio button and enter 1in the box).
That will give you a 1:1 printout.
Posted on 2004-03-26 11:18:47 by VVV
You have been really helpful. I sure appreciate it. I don't see options button. You are talking about "Viewmate" aren't you? Anyway as you know I am a begginer at this stuff other than inter-action with guy who does this, so atleast I'm familiar with footprints etc. Anyway would you mind telling me what you see in this very simple board? I mean does it look right to you? I'd like to start small like this and maybe create some new tools for my lab. This is PIC16F84 with bare minimum require parts.
If you have time thanks, and thanks anyway

addendum: I just tried the RS274X and it did same thing.
Posted on 2004-03-26 13:05:05 by mrgone
It was something wit the GRID
Posted on 2004-03-28 21:48:01 by mrgone
Hi, mrgone,

Sorry I did not reply earlier. The Options button is at the bottom of the window tha pops up when you do a "File Import...".

Anyway, I am glad you solved it.
Posted on 2004-03-29 11:29:21 by VVV