Explanation of Naming Convention |
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chads108
Active User Joined: 17 Oct 2012 Location: Plano, TX Status: Offline Points: 35 |
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Posted: 17 Sep 2014 at 1:49pm |
I just created a footprint for a SOT23 and the resulting footprint name suggested is SOT95P230X120-3L18N. I understand everything in that name except the L18 part. I am assuming it is some reference to a dimension, but I sure can't figure it out in looking at the datasheet. What is that referring to? |
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Tom H
Admin Group Joined: 05 Jan 2012 Location: San Diego, CA Status: Offline Points: 5719 |
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You have the "Extended Footprint Names" turned on in User Preferences. The L18 = the Lead Tolerance for a Gull Wing lead form. The lead tolerance impacts the pad length. A lead tolerance of 0.18 mm is good, but some Gull Wing leads have a tolerance of 0.60 mm to 0.90 mm and that makes a big difference in the pad length. Without the extended names for gull wing, the IPC-7351 calculator would auto-generate a duplicate footprint name even though the pad lengths could vary in length. I'll bring this to the attention of the IPC-7351 land pattern committee on Wednesday October 1st in Chicago, IL. |
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