Bottom solder mask omitted

[David Austin]

Bottom solder mask is omitted (perhaps if there are no apertures in it),
even though there is a bottom layer.

[Chad Parker (parker-charles)]

Can you fill in a little more detail please? Are you saying that an output gerber file is not created for the bottom soldermask layer?

[David Austin (david-d-austin)]

Yes - that's correct. In some cases, there is no output file for the bottom soldermask, even though there is a bottom layer. My guess is that this occurs when there's no openings in the bottom soldermask (no pads or pins). However, this isn't correct behaviour IMHO - it should generate a bottom soldermask file.

[Bert Timmerman (bert-timmerman)]

Hi David,

Could you add (to this bug report) a minimal example pcb file showing us this behaviour ?

TIA and kind regards,

Bert Timmerman.

[David Austin (david-d-austin)]

Please see attached PCB. It has tracks on the bottom side and so should have a
solder mask for that side. However, no solder mask is generated.

[Bert Timmerman (bert-timmerman)]

Hi David,

I tested your file and can not reproduce this bug: empty gerber files are generated for the bottom-mask, bottom-silk and bottom-paste, if the "all-layers" tick box is ticked, see the screenshots in following message.

Kind regards,

Bert Timmerman.

[David Austin (david-d-austin)]

Hi Bert,

I believe that this is still a bug. Unchecking "all-layers"
clearly suppresses any layer with no apertures. This is
incorrect behaviour for the bottom-mask when there are
tracks on the bottom layer.

Checking the "all-layers" is a work-around - but isn't ideal -
perfectly valid PCBs require manual intervention to generate
gerbers correctly.

David

[Bert Timmerman (bert-timmerman)]

Hi David,

If I do a ":ChangeClearSize(Selected,0.2mm)" on one of the vias I get a bottom-mask gerber file, as expected.

Apparently gerbers are generated on the basis of having valid and useful information (must have, not a nice to have).

If no apertures are "flashed" onto the solder mask, then the mask remains untouched, no gerber file is needed for the fab house.

Any pin or via with a non zero mask clearance would cause an aperture to be "flashed".

Kind regards,

Bert Timmerman.

[David Austin (david-d-austin)]

Hi Bert,

All fab houses that I've dealt with want a bottom mask gerber - even
if there's no apertures.

David

[Bert Timmerman (bert-timmerman)]

Hi David,

I can see where this is coming from: automated workflow and checking for completeness of received files in fab houses.

Will look into this and discuss with developer team.

Kind regards,

Bert Timmerman.