Ultiboard Print - Solder Mask Layer Print

[Lahan97]

Hello,

Using Ultiboard 12.0.  I am trying out some UV cured solder masking so I need to print out the "Solder Mask Top" layer for example on transparencies. 

What I noticed even by eye is the masking area for the pads are not the same sizes in the print, this differs with ultiboard itself as seen on Solder Mask Top Layer view.  Size difference is as much as 10%.  Attached are snippets from Ultiboard with only "Solder Mask Top" layer and pdf print of the "same" view.  Part shape is Case751-06, stock database item.

Pins 1,2,3,4 are smaller than the remaining four pins and these same pins are slightly different when the part is turned 90 degrees.

Why is there a difference?  Is it Ultiboard or the problem happens when it was printed as pdf?

[stressed_user]

Hi,

Could it be the oversize settings in the gerber properties that are causing this?

Most PCB builders prefer those settings to be set to zero.

[Lahan97]

Hi, unfortunately that is not the case, they are unchecked and zeroed.

[stressed_user]

Another possibility:

layout is drawn in metric (millimiter) and export is imperial (inches/mill) or vice-versa

I could be a conversion tolerance problem.

[Lahan97]

So there were differences between mask sizes for my system when I tried to print out the mask layer using the method attached.

However there were no differences in mask sizes when I exported the mask layer, then open it up in Gerber Viewer, then print it.

Strange.

Thanks for helping.