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Originally Posted by dsavitsk
When I open up a board file, the polygons are not filled in and there are traces all over the ground. When I push rats nest, the ground plane fills and everything looks okay.
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That's normal.
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when I run "DRC;" the lst of errors is extensive. |
My advice is to set the design rules according to your board house's manufacturing limits. Sometimes I will use even stricter limits, such as setting the minimum trace width to something higher than the default of 8 mils (?) so I can get a better price on boards. Board houses often charge more for fine-pitch trace work.
I advise against relaxing the DRC limits until the errors go away, even if you decide the errors you have now are harmless. It may be that in the future, you make what EAGLE considers to be the same class of error as one of those you disabled, but you would personally not consider them the same.
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Some of them are things that don't seem much like errors -- like the outlines of SMD resistors touching even though the pads have plenty of space. |
You're not thinking about manufacturability. What do you suppose happens to the solder when you tin one of those pads? The solder doesn't know it's not one big pad, so it flows over both of them. Maybe you don't care in that particular instance, but what the DRC limits are trying to do here is point out that you don't have any solder mask between pads.
I'll give you an example from the PINT: there's a via between one of the op-amp pins and a bypass cap hanging off of that pin. When you apply solder to the op-amp pad, the solder also flows across that via and onto the cap pad. This gave me two DRC errors (one for the via touching each pad) and I chose to ignore them, because I knew it would be populated by hand. If these were machine assembled, that could cause problems.
In the end, I had 6 DRC errors on the PINT that I chose to ignore. Every time I ran DRC, I first checked whether there were more than 6 errors. If not, then I'd just say "Del All". But frequently during development, I'd make some mistake and the DRC error list would be longer, and I'd have to do some fixing to get the error list back down to those few I was comfortable with. If I had relaxed the DRC limits to get rid of the 6 I chose to ignore, I would have missed some that I would have wanted to fix, if I had known about them.