My PCB House has stated that it sees an Insufficient Annular Ring Error on all of my drilled holes.
A typical via has a copper ring of 33 and a hole of 15 drilled at 15. That should leave a ring of 9. That should be adequate. What am I doing wrong and what setting needs to be changed. Looking closely at their error report photo, it appeard that the error is the the ID of the via is the same size as the drill size Is there a way to make the ID smaller than the drill?
Also, the solder-mask on a square pad is round, chopping the corners off-of the pad. Can that be fixed?
First off understand what their preferred manufacturing requirements are, then review your pad style sizes used in your technology in conjunction with your components pad requirements or tracking requirements for vias. The drill data you provide should be finished hole size. Also within technology - Design Rules there are settings for Minimum Pad Lands which when used with the DRC - Manufacturing - Minimum Pad Land, can run a check on them pre-manufacture. As a rule of thumb, I normally keep my pad/via minimum annulus to 11 thou, not scientific, but arrived at after too many years laying out PCB's.
If you are using the solder resist Layer Class and it is set to a value for Pad Oversize then it should emulate the pad size, not give a different shape!
OK! I figgured out how to NOT receive the annular ring error. The error was generated by the fact that the gerber creates a drill hole for the pad that is exactly the same size as the drill diameter, even for annular style pads that have ID's defined smaller than the drill size. After applying tolerances to the two holes during DFM at the board shop, there is a gap between the pad and the drill-through.
To remedy the problem, Go to.. Technology:Layer Classes:Electrical Layer:Edit and make sure "Drill Hole" is NOT checked under Draw/Plot Appearance. Also make sure "Pad Land" IS checked. "Pad Land" can't be checked here, but must be checked at.. Technology:Layer Classes:Drill (Plated):Edit
Hope that makes sense. It would be nice to have an option in technology to plot all drilled holes "x" undersize.
As for the solder-mask, I think I have found the problem, but I don't know what to do about it. My PadStack has a round pad on top & a square pad on the bottom to indicate pin 1. The solder masks seem to be inverted, with the round mask on the bottom and the square pad on the top.
Posted - 12 Dec 2013 : 17:11:47
