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PCB Supplier Questions Guard Bands

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cjurczak:
Where I work we have a fair number of older designs from before my time with guard bands, or other similar copper structures which appear to be hanging or going no where.  As these designs are moved from one PCB supplier to another, or something similar they generate a back and forth between engineering and the CAM department for the supplier. 

Does anyone document these types of structures to try and prevent these questions from a PCB supplier?  Wondering if this has come up for anyone else and how is it documented to convey the info to the supplier. 

Quick Note, not looking to get into the design decision for guard bands, just how to work with your supplier to prevent excess delays. Any thoughts would be appreciated.

jrs45:
Usually you would just thank them for pointing out their concerns but "please make them as designed".

Guard bands that aren't grounded though?

Uky:
Sometimes, the PCB fabricator requires an equal amount of copper in order to balance the etching process. The software I am using can provide what they call "thieving" which is automated creation of isolated copper "blobs", like diamonds, round pads, or similar evenly distributed over the board area.

Feynman:
It's the plating process rather than the etching process that requires evenly distributed amounts of copper.
A floating copper structure doesn't guard anything, so I wonder what the purpose of these structures is.

Apart from that any question a PCB manufacturer might have should be answered in a proper fabrication drawing ("Copper thieving not allowed in design area", "Copper thieving allowed here and there with these and those constraints", ...).

Alex Eisenhut:

--- Quote from: Feynman on July 29, 2021, 10:40:08 am ---It's the plating process rather than the etching process that requires evenly distributed amounts of copper.
A floating copper structure doesn't guard anything, so I wonder what the purpose of these structures is.

Apart from that any question a PCB manufacturer might have should be answered in a proper fabrication drawing ("Copper thieving not allowed in design area", "Copper thieving allowed here and there with these and those constraints", ...).

--- End quote ---

Me too. And in RF it is common (at least it was for me) to put notes in the fab drawing about areas that must remain unmolested with stamps and manufacturer logos (a plague)...

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