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Is it OK if pads go under an MSOP body?

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=3179
Printed Date: 25 Nov 2024 at 4:53am


Topic: Is it OK if pads go under an MSOP body?
Posted By: asdfasdfa
Subject: Is it OK if pads go under an MSOP body?
Date Posted: 17 Oct 2022 at 6:13pm
I'm working on a footprint for a part that uses an MSOP-8 package. Is it normal for the pads to go underneath the body?

The package size is 2.8 mm to 3.2 mm, and the inner edges of the pads have 2.8 mm between them. This means that on a typical package size (3.0 mm) or especially the max (3.2 mm) the pads will extend under the body.

I looked at a couple manufacturer recommended land patterns and this seems to be the case on most of them. Does anyone know why this is the case, and is this an optimal land pattern design?


Replies:
Posted By: Tom H
Date Posted: 18 Oct 2022 at 12:10pm
The SOP/SOIC pads under the Gull Wing lead plastic body is typical if the minimum "A1" dimension is greater than 0.03 mm. 

If the "A1" dimension is less than 0.03 mm then Footprint Expert will auto-trim the pad under the package. 

But you can turn Pad Trimming off in "Tools > Options > SMD Pad Stack Rules > Pad Trimmng. 

50% of Footprint Expert users trim the low-profile body pads and 50% do not trim. It's a user option. 



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