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Matt Finnerty
USA
9 Posts |
 Posted - 26 Jan 2007 : 11:46:40
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Hello,
I am making a PCB design that requires the use of rectangular pads placed at custom angles. All is well when using the software, but I'm having an issue when I try to manipulate the Gerber file output.
When I import the Gerber files into my PCB milling machine software (IsoPro), everything looks ok in the intial orientation. But if I need to change the orientation (for example rotating 90 degrees), the angled pads are no longer aligned properly. Rotation to 180 degrees does not have this problem. I sent these files to a professional PCB manufacturer (before understanding the problem) and the pads came back misaligned, therefore I assume they had to rotate the Gerber files at some point before making the PCB.
Is this angled pad rotation issue a fundamental problem with the Gerber file format, or is there some setting I can change within EasyPC to prevent this from happening? I know that I can tell EasyPC to rotate the Gerber file by 90 degrees before running the plot job, but there is no way for me to be sure that a PCB manufacturer won't rotate them again on their end (resulting in the misaligned pads).
Thank you for any help you can provide,
-Matt Finnerty
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Peter Johnson
United Kingdom
499 Posts |
Posted - 29 Jan 2007 : 06:39:38
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There's a fundamental problem that crops up all over the place. Most programs and equipment treat positive rotation in the same sense as it's used in graphs, i.e. anticlockwise. A minority go against the flow and use clockwise as positive. The mayhem that results is easy to imagine. It sounds like you may be falling foul of this.
The first thing you need to do is check the files in a Gerber viewer. There are two good free ones available at:
<www.pentalogix.com> - Viewmate
<www.graphicode.com> - GC-Prevue
They both work on the same principle as Adobe - the reader's free, but the editor costs a non-trivial amount.
If you see the right information in the viewer, the problem's likely to be one of rotation at the manufacturer. There's a setting to reverse the sense of the rotation in Easy-PC under [Output], [Plotting and Printing], [Options] button, [Gerber] button. If the viewer's wrong, check this hasn't been ticked by mistake.
If you can't resolve it, we may need to see your design and Gerber files to resolve it ourselves.
Peter Johnson
Technical Support
Number One Systems |
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Matt Finnerty
USA
9 Posts |
Posted - 29 Jan 2007 : 14:25:06
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Hi Peter,
Thanks for the reply. I downloaded the ViewMate program from Pentalogix and imported my Gerber files. All the pad orientations were correct upon import. Then, I selected all layers and rotated it by 90 degrees and it worked correctly.
We have a program called IsoPro that came with a PCB Prototyping machine (made by a company called T-Tech). When I imported the Gerber files into IsoPro, all the pad orientations are correct upon import. But when I rotate all layers by 90 degrees, the pad orientations become incorrect.
In my original post, I mentioned that Gerbers were sent out to a PCB manufactuer and that the pads were mis-oriented. After some investigating, I found out that those files did have the "Rotate Apature Macros Clockwise" option selected, which was the cause in that instance (ie: the initial import is incorrect, prior to any rotation). My current PCB Gerbers were generated without that option selected, so I've determined that the problem is not with EasyPC or the Gerbers, but rather the IsoPro software. It does not correctly rotate 90 degrees with angled pads.
Thank you for your help,
-Matt |
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Gerber File Issue