Courtyard Excess Value For Non Standard Packages |
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Batiskaff
Advanced User Joined: 30 Apr 2018 Status: Offline Points: 65 |
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Posted: 03 Jul 2019 at 3:24am |
What are the general recommendation for values of Courtyard to Body and Courtyard to Pad Excesses for non-standard packages?
For example: https://media.digikey.com/pdf/Data%20Sheets/Cooper%20Bussmann%20PDFs/EM7117xx_Series.pdf https://www.cui.com/product/resource/pj-002a.pdf |
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Tom H
Admin Group Joined: 05 Jan 2012 Location: San Diego, CA Status: Offline Points: 5718 |
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Nominal Density Standard Components use a 0.20 mm courtyard excess.
Unique Non-Standard packages us a 0.25 mm courtyard excess, but if any dimension L, W & H are over 10.00 mm then we make the courtyard 0.50 mm to make room for rework equipment. This is mostly connectors. |
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Batiskaff
Advanced User Joined: 30 Apr 2018 Status: Offline Points: 65 |
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Thank you Tom.
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5not4
Active User Joined: 09 Jul 2013 Status: Offline Points: 40 |
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Tom,
Is this for revision B or C? It seems to me most nominal courtyards in the B version are .25mm.
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Tom H
Admin Group Joined: 05 Jan 2012 Location: San Diego, CA Status: Offline Points: 5718 |
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Over the past 5 years, we have been using these Courtyard Excess values for "Standard Packages" that were tested by customers and reported great results. This has nothing to do with IPC.
The original IPC-7351B Courtyard Values were created in 2004 and are now 15 years old. New technology for Assembly machines has improved placement accuracy down to +/- 0.01 mm. There is no need for a 0.25 courtyard as it consumes too much PCB real-estate for densely populated layouts. Also, IPC-7351 has been downgraded from a "Standard" to a "Guideline" and is not to be taken literally. You must use your own common sense and advice from your assembly team to create your design rules. |
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