What is everyone using to calculate paste stencil artwork?

Question

Normally, I provide paste artwork that is 1:1 to soldermask. 
 Worked great... Until now. I finally meet an ODM who won't tune for yield. 
 Apparently, IPC7351 doesn't address this. 
 i'm happy to buy tools if anyone has suggestions. 
 Thanks.

John T · Answer

Just fyi that Allegro X already introduced a subtle feature to help with paste and soldermask pad creation. I think it's really useful but there was not much fuss made of it. 
 Just use the right mouse button and enter the increment or decrement gap to the pad layer.... (see image) 
 So no need to check the pad dims on the design layer tab, just tell the expansion values to the tool. 
 First rmb menu looks like this:

Subsequent menus look as follows: 
 
 Just fyi the assembler will likely choose a specific stencil thickness depending on their production setup such as paste type choices, or design specific reasons such as minimum component pitches, min pads sizes, versus and large paste deposits needed for large power components.( just as example). Therefore they will typically adjust the "area" of all paste deposits on the board to counter the change in stencil and to rebalance the actual "volume" of paste put down. Some of the discrete paste deposits may even be adjusted with special "v" shapes or other tricks; an example is "home base" stencil opening shape which is pretty common for caps and resistors.... 
 From my experience it is more important to adjust copper pad length/width as problems with soldering can start there, which may not be possible to fix by adjusting the paste shape alone. 
 
 Would love to hear any other experiences of designers in the field; or any other questions.

steve · Answer

The Allrgro Productivity Toolbox has a Mask Generator that will do this for you. For info look at <your_install_dir>\share\pcb	oolbox\help there is a genmask.pdf that describes the process.

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What is everyone using to calculate paste stencil artwork?

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