First time board design.

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1

Seeing as Nathan is quite busy and this is my first board which is bound to have mistakes even though I was quite careful, I was wondering if anyone could take a look at my gerber files to make sure everything is ok with my design.

It is a 2 layer board which adds a 100 ohm resistor to every unprotected I/O pin on a FPGA board that I use. It will be cut out on the dotted line included in the top layer silk screen. I didn’t add any labels to the resistor packages because they are symetric.

http://home.comcast.net/~wahconah98/wor … header.zip

Thanks,

-Bill

2

Hi Bill,

Which software are those files exported from?

I can’t check your design, but I’ve had a quick look at the gerber files. They look OK except that the octagon is an aperture macro when it could have been a simpler standard polygon. That should make no difference to manufacturing, though.

The drill file might need some minor hand editing before it can be imported, but that depends on what software is used to import it. I’ll check it in more detail later.

Steve.

3

Thanks for the response. I exported the files from Eagle after several iterations of trying to get the text sized properly. If you would like, I can post the source file for you to look at too. I have viewed the gerbers and everything is oriented and sized properly, but I’m just trying to verify that the design doesn’t violate any of the board house’s limitations.

-Bill

4

Hi again Bill,

Your board looks perfect to me, but I don’t work for SFE, sooooo…

The only suggestion I can make is that you define the border with single tracks that meet at the corners, and if possible put the border on a separate layer.

I find it fascinating that every PCB CAD package has it’s own interpretation of Gerber and Excellon formats. Gerber format documents must be better written, since all packages seem to export correct gerbers files, though still with slightly different interpretations.

But Eagle has a slightly wrong interpretation of Excellon format, so the drill file needs fiddling before it can be used. CAM350 spat out this error message trying to import the .DRD file:-

Cannot convert the following lines in file “g:\samples\eagle\spartan3 header.drd”:

Line 3:

M72

*** Unsupported header command ***

It imported correctly when I edited the header to look like this:-

M48

INCH,TZ

T01C0.0400

%

T01

X1514Y1534

…etc

Thanks for your offer to send the source file, but I’m only a gerber/excellon expert… I don’t speak ‘eagle’ :slight_smile:

Steve.

5

Do you know off hand if the boards are depaneled manually or with a CNC mill? If they do it manually I think I should be able to leave my border as it is and just update my Excellon file. If it is a CNC machine, I can make the border solid, but what format should I output it in?

Thanks again for your patience. This first board of mine has been a crash course in PCB design.

-Bill

6

Hi again Bill,

I actually don’t know what’s required by SFE/Gold Phoenix.

I’ve worked in two circuit board factories setting up jobs for manufacturing. I’ve set up about 1000 jobs, so I have lots of experience. I’m happy to give advice, as long as you know it might be wrong for SFE :slight_smile:

I seem to remember Nathan saying that Gold Phoenix mills boards.

I don’t know how Gold Phoenix programs their milling machine. This issue is not really in the customers domain. Software I’ve used for programming milling automatically follows the outline track and the centre line of that track becomes the edge of the board. If you were a customer of ours, we’d have to spend a minute or so creating a border on a special border layer. It’s only a minute, but time is money! :slight_smile:

On the other hand, I worked for another company that put ‘corner cut’ marks on boards on a copper layer. The milling guy would program his machine by targetting a scope on the corner marks. In that company, the cut would be to the inside of the corner marks so that they’d be milled off.

My opinion is that the best method for a customer to use is an outline track (which may almost certainly include arcs, if necessary) and to put the outline on a border layer. I imagine this is what SFE would do when they add your board to a panel.

If a panel consists of a set of boards with different shapes and sizes, then it’s very difficult to cut all the boards out using a guillotine style cutter, or even a v-groover, since cuts will be made across the entire panel. Nearly all PCB manufacturers would use a milling machine for panels such as SFE submits for manufacturing.

As long as the dimensions of your board are obvious, something sensible will be done with it. In the case of your board, just the corner marks would be enough if I was setting it up. Actually, if I was setting up your board I’d probably be wondering to myself “This guy’s gone to so much trouble with dotted lines, I wonder why he didn’t just use single tracks?”

hehe… It’s not that big a deal, of course :wink: If you submit your files exactly as they are, I’m sure everything will work out just fine. :slight_smile:

Steve.

7

I was lucky, Eagle has a dotted line feature! Thanks for all your help!