Re: gEDA-user: [pcb] solder mask polarity

[Xtian Xultz <xultz@ig.com.br>]

Hello Dj Delorie!!!

My PCB shop uses positive solder and componentmask when the printed 
circuit is double sided, and uses negative when single sided. Thats
because in the double sided process, they make the hot air process,
and than apply the soldermask, but before the hot air the traces 
become more... and dont know how to say that in english, but they 
go bigger, so it uses the positive film to make a photografic 
revelation.
In the single sided process, normally the hot air is not applyed.

Well, I think the better way is to have a option on the print layout.
But if it is more simple, a good way is to the software generate 
both files, like, one called pcb.output.positive_componentsilk.grp
and other pcb.output.negative_componentsilk.grp


Just my two cents...

With best regards

Xtian Xultz
Curitiba - Brazil



On Fri, 18 Jul 2003 16:36:42 -0400
DJ Delorie <dj@delorie.com> wrote:

> 
> Ok, after a number of emails back and forth with the folks at Advanced
> Circuits, I learned that the "industry standard" for solder masks is
> to print them with positive polarity (i.e. dark where you want solder
> to go) - you're specifying the reliefs, not the mask around them.
> Apparently, some shops will accept either and just fix them as needed.
> 
> Changing pcb's polarity is a one-character change.
> 
> Making it a user option is a non-trivial change.
> 
> So, my question is: has anyone submitted gerbers with positive
> polarity mask layers, and had it rejected because of that?  If the
> only rejects were for negative polarity, I'll just change the code and
> be done with it, else I'll need to add a user option in the print
> popup.
>