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Rounded Rectangle Pad Shape For SON & QFN
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chads108 View Drop Down
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Points: 35 		Post Options Post Options   Thanks (0) Thanks(0)   Quote chads108 Quote  Post ReplyReply Direct Link To This Post Topic: Rounded Rectangle Pad Shape For SON & QFN
    Posted: 18 Oct 2012 at 1:05pm
Is there a reason rounded rectangle pads are not an option for SON/QFN packages?
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Tom H View Drop Down
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Points: 5718 		Post Options Post Options   Thanks (0) Thanks(0)   Quote Tom H Quote  Post ReplyReply Direct Link To This Post Posted: 23 Oct 2012 at 7:42pm
There are only 2 SON/QFN component lead shapes - D-Shape & Rectangle
 
However, that makes no difference to your question. We'll add Rounded Rectangle pad shape option to SON/QFN packages in an upcoming release (soon).
 
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plinder View Drop Down
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Points: 141 		Post Options Post Options   Thanks (0) Thanks(0)   Quote plinder Quote  Post ReplyReply Direct Link To This Post Posted: 14 Nov 2012 at 9:44am

Is there a reason rounded rectangle pad shapes are also not available for SOD, TO, SOFL - or will those be added in the future as well?
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Tom H View Drop Down
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Points: 5718 		Post Options Post Options   Thanks (0) Thanks(0)   Quote Tom H Quote  Post ReplyReply Direct Link To This Post Posted: 14 Nov 2012 at 10:53am
Rounded Rectangle pad shape will be available in every SMT component family except Grid Array packages. This is a new feature that is planned to be implemented this year.
 
It includes QFN, SON, PQFN and PSON component families too.
 
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DaveCowl View Drop Down
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Points: 161 		Post Options Post Options   Thanks (0) Thanks(0)   Quote DaveCowl Quote  Post ReplyReply Direct Link To This Post Posted: 14 Nov 2012 at 3:35pm

Are people liking rounded rectangle for chip components (like 0402, etc.) or are they more of a leaded component thing?
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Tom H View Drop Down
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Points: 5718 		Post Options Post Options   Thanks (0) Thanks(0)   Quote Tom H Quote  Post ReplyReply Direct Link To This Post Posted: 14 Nov 2012 at 5:23pm

I think that once you intruduce Rounded Rectangle pad shape for all Surface Mount patterns (except Grid Array) then that should improve fabrication, stencil paste application, assembly reflow and inspection. 
 

I believe Rounded Rectangle pad shape is the future for several reasons, but the top is "all stencil apertures are created using laser technology and that produces a corner radius on the SMT aperture openings. So why not make the pad shape match the stencil.
 
Here are lead and lead free solder after reflow. There is no solder in the pad corners. Wouldn't it be best to shape the pad to the solder flow?

 


 
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Tom H View Drop Down
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Points: 5718 		Post Options Post Options   Thanks (0) Thanks(0)   Quote Tom H Quote  Post ReplyReply Direct Link To This Post Posted: 16 Nov 2012 at 2:28pm
We added Rounded Rectangular pad shape to SOD and TO (DPAK) in V31 coming out this weekend.
 
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