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Courtyard Size Versus Padstacks
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dwaltoneng View Drop Down
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    Posted: 13 Jun 2013 at 7:08pm
I was trying to use the FP Designer to create this component LG M47K http://catalog.osram-os.com/jsp/download.jsp?name=LG_M47K_Pb_free.pdf&url=/media/_en/Graphics/00042011_0.pdf

If I create a pad for the surface mount pins and a through hole pad for the component body, when I place the surface mount pads, the courtyard is expanded as if I had placed the large through hole pad instead of the smaller surface mount pads. I end up with a very long courtyard for the component.

If I create a pad for the surface mount pins, place the surface mount pins and then create the through hole pad and place it, the courtyard appears to be sized correctly.

I am using PCB Library Expert version: 2013.03
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Tom H View Drop Down
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Points: 5717 		Post Options Post Options   Thanks (0) Thanks(0)   Quote Tom H Quote  Post ReplyReply Direct Link To This Post Posted: 13 Jun 2013 at 7:31pm
The Placement Courtyard and the Silkscreen Outline play tricks in the FP Designer that you have to get used to.
 
When you enter the component body dimensions, the silkscreen will be intially auto-generated using those dimensions and the courtyard excess will be adjusted per those numbers plus the oversize value you enter.
 
Then when you place the pads and if they come near the silkscreen outline, the silkscreen outline will auto-adjust per your user preference rules for Pad to Silkscreen rule and move the silkscreen to obey the rule. However, the courtyard does not grow like the silkscreen. The courtyard will stay oversized to the same value as the original component body dimensions.
 
So the pads push the silkscreen to obey your rules but the courtyard follows your component body dimensions. This was hard for me to understand at first because sometimes the courtyard will look weird or irregular spacing around the silkscreen due to the pad to silkscreen clearance rule.
 
The Footprint you are trying to build is very interesting. The non-plated hole would be located at 0,0 and the 2 SMT pads are easy to place.
 
When the "Parts on Demand" (POD) website opens, the FPX file for this part should be available to everyone in the industry so that only one person enters the dimensional data and everyone else can download the FPX file, import it and auto-generate the Footprint is any CAD tool format. And can you imagine millions of component mfr. part numbers available at your finger tips ready for download.
 
 
OSRAM_LGM47K
Hyper-Bright Low Current LED
 
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dwaltoneng View Drop Down
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When I define the component body, the courtyard and silkscreen are both auto generated. When I add pads, both the courtyard and the silkscreen expand. Why does the amount the courtyard and silkscreen expand depend not only on the pads that have been placed, but also on the pad shapes that have been defined but not yet placed?
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Tom H View Drop Down
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Points: 5717 		Post Options Post Options   Thanks (0) Thanks(0)   Quote Tom H Quote  Post ReplyReply Direct Link To This Post Posted: 13 Jun 2013 at 8:15pm

I'm going to have Jeff answer this question from a programmers view point. So you'll have to wait until tomorrow for the answer.

 
I hope you're coming to the SMCBA conference in Melbourne in September -
Hope to see you there!
 
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Jeff.M View Drop Down
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In the footprint designer the silkscreen can get pushed out to comply with silk-to-pad clearance rules.
 
When this happens the courtyard can also, but not necessarily always, get pushed out to keep the silkscreen inside the courtyard.  
 
If the shape is square or rectangular, this should only happen on a side where the violation occurs.  
 
If you can provide a screen image I may be able to explain further or a correction may be required in the software. 
 
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dwaltoneng View Drop Down
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It turns out that it is the order that you define pads in that makes the difference. If you define the surface mount pad first, when you place the pad, the courtyard will be adjusted to fit that pad. If you define the large through hole pad before the surface mount pad, when you place the surface mount pad, the courtyard is adjusted as though you placed the through hole pad.
 
Surface mount pad defined first -
 

 
Large through hole pad define first, but not placed
 
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dwaltoneng View Drop Down
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Is this behavior expected?
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Jeff.M View Drop Down
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Points: 477 		Post Options Post Options   Thanks (0) Thanks(0)   Quote Jeff.M Quote  Post ReplyReply Direct Link To This Post Posted: 24 Jun 2013 at 5:58pm
I'm having a hard time figuring out what the problem is here.
I don't see a hole in  pictures provided for this part.  The data sheet is incomplete in that it provides no body details and from what I can do in the way of trying to reproduce the report isn't exposing any problem.  Plus the solder mask as defined is can not be created in the FP designer.
Can you provide a more detailed explanation?
We may need an on-line meeting.
Thanks.
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dwaltoneng View Drop Down
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Originally posted by Jeff.M Jeff.M wrote:

I'm having a hard time figuring out what the problem is here.
I don't see a hole in  pictures provided for this part.  The data sheet is incomplete in that it provides no body details and from what I can do in the way of trying to reproduce the report isn't exposing any problem.  Plus the solder mask as defined is can not be created in the FP designer.
Can you provide a more detailed explanation?
We may need an on-line meeting.
Thanks.

Page 9 of the data sheet http://catalog.osram-os.com/jsp/download.jsp?name=LG_M47K_Pb_free.pdf&url=/media/_en/Graphics/00042011_0.pdf I quoted in my original post does provide body details.
This part is a reverse mounted LED. The entire body of the part sits in a 2.7mm hole.

Please try the following sequence:
Define a rectangular body H=0.4 W=1.5 L=2.1
Define a 1.1 x 0.6 surface mount pad.
Define a non plated through mounting pad with a 2.7mm hole.
Place two of the surface mount pads at 3.6mm centers.

Please reset and try the following sequence:
Define a rectangular body H=0.4 W=1.5 L=2.1
Define a non plated through mounting pad with a 2.7mm hole.
Define a 1.1 x 0.6 surface mount pad.
Place two of the surface mount pads at 3.6mm centers.

The previous two sequences yield different results, even though the through hole pad has not even been placed yet.
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dwaltoneng View Drop Down
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Points: 193 		Post Options Post Options   Thanks (1) Thanks(1)   Quote dwaltoneng Quote  Post ReplyReply Direct Link To This Post Posted: 02 Jul 2013 at 4:23pm
I just tried repeating the steps listed in the previous post, but this time I saved both of the results to a library. When the components were created, they looked like the screen shots in an earlier post, but when I retrieve them from the library, they both looked the same as the screen shot for "Surface mount pad defined first". This is possibly because the pad stack for the unused through hole pad has been discarded.
If I actually place the central hole, the problem remains.

tst_3 sequence:
Define a rectangular body H=0.4 W=1.5 L=2.1
Define a 1.1 x 0.6 surface mount pad.
Define a non plated through mounting pad with a 2.7mm hole.
Place the hole at 0,0.
Place two of the surface mount pads at 3.6mm centers.

tst_4 sequence:
Define a rectangular body H=0.4 W=1.5 L=2.1
Define a non plated through mounting pad with a 2.7mm hole.
Define a 1.1 x 0.6 surface mount pad.
Place the hole at 0,0.
Place two of the surface mount pads at 3.6mm centers.

uploads/2945/courtyard_test.fpx shows the results of defining the component.
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