DFM Violations on BeagleBone Gerber Files

I imported the Gerber files for the C revision of the BeagleBone and
sent them off to Pentalogic for a DFM review. They came back with a
few issues.

One was the difficulty of importing the drill file. I found that I
had to explicitly tell Viewmate the format for the drill data, 2
digits left and 5 digits right of the decimal point. Pentalogic
seemed to just toss the file and extract the data from the Fab
drawing.

They found a 30 mi, unplated hole in the center of the reset switch
which has no clearance around it on the power and ground layers. The
hole is also not listed in the drill chart. They suspect the hole
should not be there.

Is this hole needed? Why no clearance?

Does rev A4 use the same PCB as rev A3?

Rick

Hi RIck, I can help you. The PCB rev A3 is rev.C and for rev A4 and rev. A5 il rev. C1. This is write on BeagleBONE schematic rev. A4 and rev.A5

Alex

There is a nipple in the middle of that switch for alignment. Without that hole the switch has a tendency not to sit flush with the pads on the PCB. If you ;look at the schematic, you wiwll see that Rev A3 uses Rev C1 PCB and Rev A4 uses Rev C2. You can also read the SRM under changes, and it describes the changes to the PCB that were made between Rev A3 and Rev A4 assemblies.

I use Viewmate on the Gerbers. But, I will check and see if there are alternate more friendly ways of doing Gerbers under Allegro.

Gerald

Alex is correct. rev C2 comes in on revision A6 which we just completed.

Gerald

There is a nipple in the middle of that switch for alignment. Without that hole the switch has a tendency not to sit flush with the pads on the PCB. If you ;look at the schematic, you wiwll see that Rev A3 uses Rev C1 PCB and Rev A4 uses Rev C2. You can also read the SRM under changes, and it describes the changes to the PCB that were made between Rev A3 and Rev A4 assemblies.

I use Viewmate on the Gerbers. But, I will check and see if there are alternate more friendly ways of doing Gerbers under Allegro.

Gerald

ViewMate often has trouble detecting the right format for drill files. I learned to use ‘import directory’ for the entire stack, or only ‘guess’ for a single (drill) layer.

— Bas

I just loaded the Gerbers into GerbV version 2.5.0 and they look OK.

Gerald