What are your clearance and mask settings for pcb design? - Page 1
Forum section: electronics / projects

author: alank2
author_rank: Super Contributor
timestamp: November 12, 2015, 03:34:36 am
content: Two settings specifically -Clearance for the ground pour - I was using 0.2mm (7.87mil)Mask - I was using 2mil - but I wonder if iteadstudio adjusts this value on different pad sizes.My problem - one of the pcb's I did by hand had a couple of shorts in two tracks. Same problem, the edge of the ground pour was not fully covered by the slightly off center mask and I put a bit too much solder on the joint shorting the track to ground.What do you use for these values? I am thinking of using 0.25mm for the clearance pour and 0.08mm for the mask...

author: tggzzz
author_rank: Super Contributor
timestamp: November 12, 2015, 08:55:14 am
content: The answer will depend on many factors, including your fab house's capabilities and your design constraints - e.g. you will have different answers for audio, digital, RF, low current and high voltage circuits.

author: Karel
author_rank: Super Contributor
timestamp: November 12, 2015, 09:34:16 am
content: It all depends on what exactly you want to design and the capabilities of the boardhouse.We use one of the DRU files from here:http://eurocircuits.com/blog/48-V6These design rule files contain all settings needed to make your board comply with the design class you selected.During routing, your pcb software will show immediately when you are violating one of those rules.Because of that we never had any problems with the boardhouse and we never experienced the problems you described.

author: T3sl4co1l
author_rank: Super Contributor
timestamp: November 12, 2015, 01:38:00 pm
content: Noncritical applications:Pour clearance, minimum width: 10 mil (~0.25mm)Mask expansion: 4 mil (~0.1mm)For quality boards and fine pitch, I try to keep the same pour dimensions, else relax to global tolerance (7 or 6 mil), mask expansion/min width 2.5 mil.Tim

author: alank2
author_rank: Super Contributor
timestamp: November 12, 2015, 01:43:08 pm
content: Thanks Tim - I dug out the DRU file at itead and they have it set to 6mil clearance and 2mil masks. I guess I just had a bad pcb from them where the mask was right on the edge of covering the ground plane and I had too much solder on the join. I'm going to go with 0.25mm clearance and 0.8mm mask unless I have a need to change it.

author: T3sl4co1l
author_rank: Super Contributor
timestamp: November 12, 2015, 01:51:45 pm
content: That sounds awfully optimistic for a budget manufacturer!Tim

author: alank2
author_rank: Super Contributor
timestamp: November 12, 2015, 03:23:52 pm
content: Quote from: T3sl4co1l on November 12, 2015, 01:51:45 pmYep.I think I am going to add a single grounded square SMD pad in the four corners of a board so I can see the mask alignment easily. I'm also going to move to 0.25mm clearance instead of 0.20mm unless I have a reason to go smaller.

author: T3sl4co1l
author_rank: Super Contributor
timestamp: November 12, 2015, 10:56:06 pm
content: Yeah, I route with 10/10 rules until I need to go finer. Which usually means using 10 mil traces and 10 mil grids and a 6 or 7 mil clearance limit. Only use what you need!Tim

author: crazy horse
author_rank: Contributor
timestamp: November 13, 2015, 02:08:32 am
content: 0.3mm, but depends what pcb fab quality you are paying for.