Footprint Error Pad-Pad clearance fail
Printed From: PCB Libraries Forum
Category: PCB Footprint Expert
Forum Name: Questions & Answers
Forum Description: issues and technical support
URL: https://www.PCBLibraries.com/forum/forum_posts.asp?TID=2283
Printed Date: 16 Nov 2024 at 5:41pm
Topic: Footprint Error Pad-Pad clearance fail
Posted By: wawaus
Subject: Footprint Error Pad-Pad clearance fail
Date Posted: 22 Jan 2018 at 11:54pm
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Generating a footprint for a Vishay-Siliconix DG2722 Library fails to maintain the specified Pad to Pad clearance with the clearance rule set at 0.2mm. Between pads 1-10, 2-3, 5-6, 7-8 it delivers a clearance of only 0.14. To achieve the clearance, dimension S1 should have increased to 1.0mm. Is this behaviour expected? Have I missed something? Bill |
Replies:
Posted By: Tom H
Date Posted: 23 Jan 2018 at 7:33am
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I cannot find this part on http://www.pcblibraries.com/POD " rel="nofollow - www.pcblibraries.com/POD ; The Vishay DG2722 datasheet - https://www.vishay.com/docs/68379/dg2722.pdf " rel="nofollow - https://www.vishay.com/docs/68379/dg2722.pdf ; Indicates that the footprint requires a longer Pin 1 and therefore must be created in FP Designer using the mfr. recommended pattern. The Preferences > Rules > Minimum Pad to Pad is for Standard Calculated parts only and does not have anything to do with custom FP Designer footprints that use the mfr. recommended patterns. ------------- Stay connected - follow us! https://twitter.com/PCBLibraries" rel="nofollow - X - http://www.linkedin.com/company/pcb-libraries-inc-/" rel="nofollow - LinkedIn |
Posted By: wawaus
Date Posted: 23 Jan 2018 at 2:48pm
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Hi Tom, I accept your comment about the Mfr recommended pattern, but that does not change the fact the calculated footprint Did Not maintain the clearance I specified between the end of one calculated pad and the side of another adjacent calculated pad. Bill |
Posted By: Tom H
Date Posted: 23 Jan 2018 at 2:53pm
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I don't know how you created a QFN with a longer Pin 1 in the Calculator, it does not have that feature. Never seen this issue in the past 15 years. ------------- Stay connected - follow us! https://twitter.com/PCBLibraries" rel="nofollow - X - http://www.linkedin.com/company/pcb-libraries-inc-/" rel="nofollow - LinkedIn |
Posted By: wawaus
Date Posted: 23 Jan 2018 at 7:50pm
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I did not create it with a longer pin 1, I created a symetrical footprint, but with a 0.2mm clearance requirement the corner pads are closer than the the clearance specified and there was no warning that the rule had been violated. |
Posted By: wawaus
Date Posted: 23 Jan 2018 at 7:53pm
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I tried to add some screenshot snips but they appear not to have gone through. |