Default solder mask clearance for footprint editor


#1

My default solder mask clearance value is of primary concern. Previously, when solder mask was not displayed during footprint editing, I never payed attention to it. But in OpenGL view it is being displayed and you can see right away that It is set to some higher value than that which is selected in PCBNew -> Dimensions -> Pads Mask Clearance. I have to edit every pad separately to adjust that value. It seems to be set to 6mil and industry minimum on average is 3mil. Is there a way to set a default value for solder mask clearance for the footprint editor? I’m using 4.0.1 stable version


#2

You should leave the pad’s clearances at 0. If you do this you can set the clearances for each pcb with Dimensions -> Pads Mask Clearance.
If you set it in the pad itself the pcb’s settings will be overwritten for this pad.

Edit: This is wrong
If you want to change the footprint editors view, you need to edit your template project. (The footprint editor uses the settings of this project, not the one you have currently opened.)


#3

That goes without saying (although I actually had said it) that default value refers to the value of a new pad being placed, thus its clearance setting had not been modified (i.e. 0).

I didn’t follow your suggestion about a project template. How do you change that? What is the difference between “this project” and a project “currently open” May be it is me, but I would think that default values for footprint editor should be independent of any projects.


#4

Did that change recently…?
I’m still on nightly 2016-11-19 rev 888c5d2.

The template.pro has 0.0 for soldermask and still there is a distance in OpenGL view mode in the editor?!

I remember we had this discussion some time ago in regards to the 3D viewer as well… but can’t remember details.


#5

It always been like that. Like I said, in default mode the solder mask clearance was not displayed, so you couldn’t really see if the default clearance of the footprint was the same as the default value for solder mask clearance selected in PCBnew


#6

No i’m just wrong. (My memory has left me it seems.)

Found the discussion:

And a good explanation about why global/local clearances. (Showcasing the different viewpoints.)


#7

Your quoted “explanation” didn’t make much more sense than your original response. It is just plain dumb to say that there shouldn’t be a “global” clearance value. Global values make sense - all the footprints with no local clearance values not selected (local clearance set to 0) get assigned the global value. Which is convenient so you don’t have to change each footprint individually. What’s the alternative?! Leave them at zero and generate gerbers with zero clearances? PCB manufacturers can’t make boards like that.

However this is not what I"m trying to discuss here. My question is about default clearance in the footprint editor being some other value rather than the one selected in the PCBnew.


#8

Only the Devs on the mailing list will have that answer (or one of them shows up here and replies, who knows).

Afaik, in the past the editor used the settings from pcbnew… some time ago that changed and the editor got stuck (for visualizing) on some odd 0.3 mm for the soldermask clearance visualization in OpenGL and the 3D viewer, although it’s set to 0 for the footprint and saved like that in the footprint file and works like that in pcbnew.
:neutral_face:


#9

Got it, thanks! I thought I was missing something.


#10

Yeah, it’s a bug.
I think they know it’s there, but hadn’t had time to fix it yet (minor).
Annoying for sure.


#11

I assume you stopped reading after the first post (by nicolas)
If you have read the whole discussion (yes all 15 posts) you would understand that there are different views on this.
Already the second post (by joan_sparky) explains why global settings are usefull.

What i wanted to show is that there are different legitimate views on what should be used. Each with its own advantages and disadvantages. Everyone should decide for themselves what suits their usecase.

(But yes after reading your question again, this is not what you asked for. The part of my answer that was wrong would have answered your question if it would have been correct. Sorry for that.)


#12

This statement is not true. PCB manufacturers typically alter your gerbers and change clearances to suit their production capabilities. Resist and paste layer changes in particular don’t usually even get a mention when they are changed, because its very rare they aren’t altered.

There are pro’s and cons of different amounts of clearance (or using any at all), but setting the clearance to zero and allowing the PCB manufacturer to increase it as they require is perfectly acceptable approach, and often gets the best results.


#13

You contradict yourself. The statement that PCB manufacturers can’t produce boards with zero clearances is correct. According to your own words the manufacturer will adjust the solder mask clearance based on their manufacturing tolerances. They are not going to leave it at zero. While I would agree that leaving footprints which don’t require high tolerances for the solder mask at zero and then applying global setting when generating Gerber files is a perfectly acceptable approach, I don’t think that sending out Gerbers with zero clearance for manufacturing is a good practice. Yes most manufacturers will adjust it for you, but not based on your footprint specifics, but simply by increasing apertures until they meet min clearance requirement. This can be a recipe for problems especially if you have high tolerances and high pitch components and your manufacture min tolerances are high.

Be it as it may, that’s not really the subject of the discussion here.