Footprints / Land Patterns - Maximum Height in Footprint Naming Convention

Maximum Height in Footprint Naming Convention

Printed From: PCB Libraries Forum
Category: Libraries
Forum Name: Footprints / Land Patterns
Forum Description: [General or a CAD specific issues / discussions]
URL: https://www.PCBLibraries.com/forum/forum_posts.asp?TID=2487
Printed Date: 22 Nov 2024 at 4:16am

Topic: Maximum Height in Footprint Naming Convention

Posted By: sebgonzo
Subject: Maximum Height in Footprint Naming Convention
Date Posted: 21 May 2019 at 4:27am

Sorry if this has already been answered, but I couldn't find it.

Why in PCB footprint naming height dimension is specified as maximum, where others are nominal?

I can not find any good reason for this exception.

In my opinion this creates many exactly the same footprints only with different name because of height tolerance differences.

Replies:

Posted By: Tom H
Date Posted: 21 May 2019 at 8:31am

For 2 main reasons -

We see millions of component datasheets and many of them only provide the Maximum height dimension. We cannot guess at what the Nominal dimension might be. However, they always provide the maximum height dimension even if they provide the Nominal + tolerance. So basically every component datasheet (and there are 100 million of them) always provide the Maximum height.
The 3D STEP model name is the same as the footprint name. In 3D modeling, Maximum height is really important for validation in the enclosure.

However, there are 3D Modeling controls in the CAD tool interface to select Nominal or Maximum density level.

Also, most people do not think to consider the solder under the leads that lift the part up. So, by using the Maximum height you kind of compensate for the solder buildup.

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Posted By: sebgonzo
Date Posted: 23 May 2019 at 2:27am

OK, thank you for quick answer. This makes sense now Smile