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 Large pad stencil divider
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AndyB

United Kingdom
207 Posts

Posted - 14 Dec 2016 :  16:03:50  Show Profile  Reply with Quote
Can EasyPC divide large pads stencil into smaller divisions?

edrees

United Kingdom
697 Posts

Posted - 14 Dec 2016 :  16:16:52  Show Profile  Visit edrees's Homepage  Reply with Quote
I find that this is normally automatically done by the stencil manufacturer. You can do it with EPC but you will have to modify the rest of the S/mount components in your design to include a solder paste layer (in Component Editor) -otherwise when you come to plot the paste layer you will end up with big problems (unless someone else knows better?). Exceptions on top of exceptions etc!
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Iain Wilkie

United Kingdom
986 Posts

Posted - 14 Dec 2016 :  21:05:49  Show Profile  Visit Iain Wilkie's Homepage  Reply with Quote
On the solder stencil layer create an exception for the pad in question and set it to zero size. Then on the stencil layer create the pad pattern you want over the actual pad. Just watch if you move the part that you move the stencil pattern with it !

Iain
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edrees

United Kingdom
697 Posts

Posted - 15 Dec 2016 :  09:18:33  Show Profile  Visit edrees's Homepage  Reply with Quote
Thanks for sharing that "work-around" with us Iain!
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AndyB

United Kingdom
207 Posts

Posted - 22 Feb 2017 :  15:16:14  Show Profile  Reply with Quote
Thanks Iain I will try that out.
Maybe they may add this to the next version.
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ianafh

United Kingdom
24 Posts

Posted - 22 Feb 2017 :  15:30:02  Show Profile  Visit ianafh's Homepage  Reply with Quote
You can use a similar pad exception technique in the symbol editor. If I recall correectly it goes wrong if you have defined shapes on the top solder paste layer and then use the component on the bottom side of the board. The paste ends up on the wrong side.

Ian.
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DavidM

United Kingdom
458 Posts

Posted - 22 Feb 2017 :  15:42:50  Show Profile  Visit DavidM's Homepage  Reply with Quote
As long as you have matching 'pairs' of top/bottom layers of the same type, shapes defined in the footprint should flip to the opposite side of the board when you mirror the component.

David
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edrees

United Kingdom
697 Posts

Posted - 05 Jul 2017 :  12:46:36  Show Profile  Visit edrees's Homepage  Reply with Quote
Further to Ianafh's comment, I'm not sure that by using the PCB Symbol Editor to make a zero sided exception on the solder paste and then add smaller areas of solder paste "shapes" actually works. The component looks correct in the PCB Symbol Editor with the smaller solder paste "shapes" replacing the larger "pad" of solder paste, but on the PCB Design Editor the solder paste shapes are not visible (neither do they print or plot) or the original large heatsink pad is visible (depending on layer exception settings in PCB Editor). It appears that the solder paste "exception" to the pad made in the PCB Symbol Editor does not automatically appear in the Tech file of the PCB Editor when the component is imported.

Either way, I can only achieve what I require by using Iain's suggested work around. Maybe I'm missing something?

PS. Even if I modify one of the solder paste shapes to extend past the original copper pad it does not appear as expected when imported into the PCB editor!

Edited by - edrees on 05 Jul 2017 16:45:07
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edrees

United Kingdom
697 Posts

Posted - 06 Jul 2017 :  12:43:15  Show Profile  Visit edrees's Homepage  Reply with Quote
With help from Ianafh, (many thanks Ian) I managed to understand what was going on and achieve the result I wanted by adding additional single layer pads to the component. However, it does appear that the Solder Paste layer behaves differently to the Solder Resist Layer. Areas of Solder Resist added to a component in the Component Editor do transfer through to the PCB editor when the Component is imported. However, areas of solder paste do not. My "instinctive" method of making a zero sized solder paste exception (in the Component Editor) then adding multiple solder paste "shapes" within the original pad area doesn't work (despite EPC allowing you to do it!). An "All Layer" pad (with possible zero sized pads on "unnecessary" layers) with further solder paste exceptions may also be necessary to achieve what is required.

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Iain Wilkie

United Kingdom
986 Posts

Posted - 06 Jul 2017 :  14:00:05  Show Profile  Visit Iain Wilkie's Homepage  Reply with Quote
Ed,

I'm pretty sure you can do this. In the component footprint editor you give the big pad a zero size on the paste layer and add the small paste blobs on the paste layer.
When imported as a part on the PCB editor, you will see the big pad paste as normal, but if you set the paste layer for the pad to zero the smaller blobs will appear ..... I think .... I can't check at the moment but I'm pretty sure I have done this in the past.

Iain
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edrees

United Kingdom
697 Posts

Posted - 06 Jul 2017 :  14:22:00  Show Profile  Visit edrees's Homepage  Reply with Quote
Hi Iain.

It's what I would have expected too, -my "intuitive" approach, but sadly it doesn't seem to work for me.

I've set the paste layer for the "big" pad to zero in the Component Editor. then added smaller solder paste shapes. I would have thought that this pad (solder paste =0 Size) exception would automatically follow through into the PCB Editor on Importing the Component, but it doesn't! Neither does the Solder Paste shapes added in the Component Editor appear to import into the PCB Editor. (Yes relevant layers are all enabled as necessary).

The exception shouldn't have to be done in the PCB Editor, (when you manually add Solder Paste Shapes after making the exception,- which does work). It should be a feature of the Component itself.
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edrees

United Kingdom
697 Posts

Posted - 07 Jul 2017 :  11:16:09  Show Profile  Visit edrees's Homepage  Reply with Quote
Think I've resolved the issue with help from both ianfh and IainW. Thank you both for your time and examples. Looks like myTech/Design files had got corrupted and contained two solder paste layers. A "fresh" Tech file seems to resolve the issues I was experiencing. Now the solder paste layer behaves "intuitively"!
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neilh

USA
23 Posts

Posted - 14 Dec 2017 :  05:53:25  Show Profile  Reply with Quote
quote:
Originally posted by AndyB

Can EasyPC divide large pads stencil into smaller divisions?


I'm also having a problem.
I think this is supposed to be on the paste layer and discussed in
https://www.numberone.com/faq.aspx?KB020093
but for the life of me I can't make it work in practice.

Is it possible that the FAQ tutorial can be written with an actual example and menus that need to be used.

I'm trying to use a Nxp/Freescale MKL27Z256VFT4 QFN48 - 5x5mm with 0.5mm spacing and a power tab underneath.
http://cache.freescale.com/files/shared/doc/package_info/98ASA00616D.pdf
So I'm assuming that if I can do it at the PCB symbols library it should be forever done when it is included.
I initially created it as 48 pads, and added a 49th pad.
Now trying to modify a paste layer to generate the right output - So far I've spent about 3hours trying to implement just the paste layer.
The result "QFN48_7x7x0_5mm.psy" is here at
https://drive.google.com/open?id=1txWCrzCNXDnDF-uusu14yP4S6r_VPZ4x

Many thanks for any insights
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