Altium Solder mask expansion rule.

[titium]

In the video linked below dave makes reference to setting the solder mask expansion rule to 1.5mil however after speaking to the manufacturer PCBzone in NZ, they have told me he lowest I should go for is 8mil.

I guess what im asking is, are there any manufacturers that do small quantity boards (at a decent price) that can go down to 1.5mil. Or should i just not bother with the solder mask between the pads.
With the 8mil rule I have no solder mask (or very little) between IC pins particularly the ones with smaller pitch (0.5mm-0.65mm)

[ludzinc]

In the video linked below dave makes reference to setting the solder mask expansion rule to 1.5mil however after speaking to the manufacturer PCBzone in NZ, they have told me he lowest I should go for is 8mil.

I guess what im asking is, are there any manufacturers that do small quantity boards (at a decent price) that can go down to 1.5mil. Or should i just not bother with the solder mask between the pads.
With the 8mil rule I have no solder mask (or very little) between IC pins particularly the ones with smaller pitch (0.5mm-0.65mm)

Smallest Solder mask 'sliver' should be 8mil.  If you have a 1.5 mil expansion, that equates to pad edges being no closer than 11mil.

[titium]

here is the reply i got from pcbzone when i asked if i should reduce the solder mask expansion

"If you were to reduce the grow on the mask openings i think we would run into alignment issues, so i would leave it as is. It should still solder fine."

They then went on to say that the solder mask expansion should be >8mil preferably 10mil

[Precipice]

Or should i just not bother with the solder mask between the pads.

This...
There shouldn't be any copper between pads, so what are you hoping the solder mask will do? At fine pitches, you just need to get things right, and surface tension will make it all work.
There always comes a point where it's not worth it. Granted, 8mil expansion and 8mil sliver is quite old-school, and it's easy enough to find a fab that can beat it if you want to pay, but short answer, don't sweat it.

[marshallh]

Depends on the fab's processes. I use 3mil expansion and haven't had a problem. Then again most of my boards use pretty fine pitch small parts.
Modern LPI soldermask lets you get away with really small necks like this.