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Pad Stack Name for Through Hole Parts

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=1432
Printed Date: 07 Nov 2024 at 8:13pm


Topic: Pad Stack Name for Through Hole Parts
Posted By: PLTcbv
Subject: Pad Stack Name for Through Hole Parts
Date Posted: 25 Sep 2014 at 1:43am
If I create a Through Hole part with the LE Lite 2014.11 and do an Expedition ASCII out the Padstack name used in the part is not correct.

Padstack created: c150m160h100t140_180_34

Padstack Naming Convention: c150h90m165

Hole and Mask position in Padstack name are different.

Which is correct?

Regards,

Wim.


Replies:
Posted By: Tom H
Date Posted: 25 Sep 2014 at 7:35am

It totally depends on what "Environment" you are using.

If you are using IPC-7251 Level A, B & C then the Pad Stack name = c150h90m165

If you are using Proportional Environment the Pad Stack name = c150m160h100t140_180_34

For the Proportional Environment the Thermal Relief ID t140_180_34 is added because the way IPC-7251 calculates Thermal Relief is entirely different than Proportional.

IPC uses the Pad Size to calculate Thermal Relief and Proportional uses the Anti-pad to calculate the Thermal Relief.

The big difference is that the Anti-pad is a much more stable number because it's calculated by the hole size which is always consistent. The Proportional "Pad Diameter" gets proportionally larger as the hole size grows while the IPC pad stack annular ring is the same regardless if the hole in small or large.



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