DRC bot butchers my gerbers (FreePCB, fine in Viewmate)

Archive BatchPCB
1

I’m a new user of BatchPCB and I’m running a test file through to see if I’ve got everything right.

I’m using TinyCAD - FreePCB to layout my board and generate the gerber files.

I’ve opened my gerber files in Viewmate and everything looks perfect. Didn’t have to alter any settings, just import and I’m good.

Wish I could attach files to this forum… Where can I send my offending files?

The answer I get form the DRC bot when I’ve submitted my gerbers shows my top copper power plane filled in solid, and most of my traces 3x the width they’re supposed to be. Needless to say, the bot is highlighting DRC errors in places where there’s plenty of separation when viewed with Viewmate. Also my bottom copper layer shows up as solid. I’ve got a copper fill area ground plane covering all of the bottom layer.

In another post it’s mentioned that the DRC bot can’t handle negative draws? It’s looking like FreePCB uses those heavily when it makes a copper fill area.

I’ll try to respond this weekend, but Monday is when I’ll have access to all my files again.

Thanks,

Marty

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The bot currently does not handle negative draws [the next version will, but thats a ways off, have to rewrite its entire geometry engine].

For special cases where the bot absolutely butchers stuff, just contact support at the batchpcb domain and we’ll get them put into the system.

Cheers,

–David Carne

3

Thanks David. I’ve already sent an e-mail to batchpcb support about this like you suggested.

Just so everyone has a clue what’s happening.

ViewMate sees my top copper layer like this.

{broken link}

While the DRC bot thinks it looks like this.

{broken link}

Same gerber file in both cases. The gerbers were generated with FreePCB. I’ll have to do further testing some other time to see If I can get FreePCB to make gerber files that the DRC bot understands.

Marty

Edit: my images above were hosted by a service that died.

4

I’m getting close to submitting a new PCB design generated with FreePCB. I understand that the Bot has been having some issues with the negative draw that FreePCB uses. Is this better now? I just submitted a test PCB and it was rejected because some of the traces were too close. The traces were actually farther apart, but the Bot had drawn them with 25mil paths instead of 10mil paths that were designed.

Any workarounds besides the manual intervention?

Thanks for a great service.

5

I just checked today and the DRC bot still treats ‘negative’ or ‘scratch’ draws just like normal draws. This is a problem for FreePCB because FreePCB draws any layer with copper areas by filling the copper area(s). FreePCB then uses negative draws to separate any traces from the copper area(s). A work around is to just not use copper areas. Alternatively, nicely e-mail BatchPCB and have them add the design manually.

Marty

6

Has anyone actually submitted FreePCB gerbers which include a copper pour and had them manufactured? I am using FreePCB for a simple backplane which was too big for Eagle (which I normally use). It passes DRC fine, but the images emailed back show one big solid copper area on the top and bottom (but are perfect in ViewMate). Sounds like the “negative” problem described below. In my case, they pass DRC fine so I could submit them, but would hate to get back a board that matched the DRC bot image.

Thanks!

7

Yes I’ve had my boards manufactured. They included a copper pour on the bottom and a small pour on the top. After getting BatchPCB support to manually pass the boards through DRC, they came back perfect.

Marty