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| Paste Mask Question | 
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| vavouris   New User   Joined: 18 May 2018 Status: Offline Points: 4 |  Post Options  Thanks(0)  Quote  Reply  Topic: Paste Mask Question Posted: 24 May 2018 at 5:50am | 
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   Hi, I'd like to ask what is the general guideline for paste stencils.  Should the stencil be same size as the pad, smaller or greater?  I know that in BGA packages we want very few solder paste on the pad. And on other packages, I was creating a paste mask figure 70% of the pad.  I am a bit confused now, and I don't know if should continue to do that or leave it 1:1 and let the assembly plant deal with it. Thanks, Theocharis | |
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| Tom H   Admin Group     Joined: 05 Jan 2012 Location: San Diego, CA Status: Offline Points: 5949 |  Post Options  Thanks(0)  Quote  Reply  Posted: 24 May 2018 at 6:08am | 
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   For Standard SMD pads the Paste Mask aperture size is 1:1 scale.  For Thermal Tab pads the Paste Mask Reduction is between 40 - 60%. | |
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| vavouris   New User   Joined: 18 May 2018 Status: Offline Points: 4 |  Post Options  Thanks(0)  Quote  Reply  Posted: 24 May 2018 at 6:15am | 
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   Thank you! That was fast.
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| Tom H   Admin Group     Joined: 05 Jan 2012 Location: San Diego, CA Status: Offline Points: 5949 |  Post Options  Thanks(0)  Quote  Reply  Posted: 24 May 2018 at 6:19am | 
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   If you use Rectangle Pad Shape, the Paste Mask aperture will be Rounded Rectangle, so you might as well use Rounded Rectangle for the pad shape too.  | |
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