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Zero Component Orientation, Level A or B? |
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Batiskaff 
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Joined: 30 Apr 2018 Status: Offline Points: 65 |
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 Topic: Zero Component Orientation, Level A or B?Posted: 07 Mar 2019 at 5:52am |
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PCB Library Expert uses the "IEC 61188-7 Level B" zero component orientation.
Why not "Level A"?
As I understand "Level B" will be more prefer in IPC-7351C ? |
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Tom H
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Joined: 05 Jan 2012 Location: San Diego, CA Status: Offline Points: 5718 |
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Posted: 07 Mar 2019 at 8:22am |
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Because IPC-SM-782, IEC 61188-7, Valor VPL, EIA-481 and every other standard in the world uses Level B.
IPC-7351 is the only guideline that uses Level A and they should have never choose that. I've been on the IPC Land Pattern committee since 1999 and we created the first IPC calculator and everything was Level B Orientation. We drafted IPC-7351 in 2004 and it was Level B. We had a meeting at IPC APEX in the winter of 2005 and the chairperson all of the sudden spoke up and wanted to introduce Level A and the attendees not knowing the past of the future voted in favor with her. It was the biggest mistake IPC ever made. Then we has to change all the zero orientations in the software program and that took 3 months of coding and set everything behind schedule. So, the IPC-SM-782 that was released in 1987 and was the standard for 18 years had Level B Orientation. Why we accepted to change it was a huge mistake. |
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