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Class A (Most) Land Pattern Extended Pads

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=3391
Printed Date: 21 Nov 2024 at 4:52pm


Topic: Class A (Most) Land Pattern Extended Pads
Posted By: Alex Quilty
Subject: Class A (Most) Land Pattern Extended Pads
Date Posted: 11 Jun 2024 at 7:28am
Hey everyone,

My understanding for IPC's Class A Land Patterns is that they perform just as well as Class B (Nominal) Land Patterns. I also know that the Class A Land Patterns have been kept for those who may be soldering the component to the PCB by hand. Finally, where I am a little confused, is where a particular Pad may be too small or too big, this could cause issues in manufacturing to IPC Class specifications depending on the size, which leads me to the question: 

Is it okay to extend my Pads to allow for easier hand soldering? If so, how much longer am I allowed to make these Pads before it degrades the Fillet too much, since the solder would be spreading along the Pad instead of climbing the lead to form the Filet?

Edit: I just noticed the Land Pattern Forum section, I can move this there if you would like, otherwise I will leave it here, or if a MOD could move this post, that would be awesome! Let me know if you want me to move it.



Replies:
Posted By: Tom H
Date Posted: 11 Jun 2024 at 8:30am
You can't manually solder BTC or Grid Array parts, and Gullwing parts don't require a lot of solder on the Toe. 

However, 80% of the parts on a typical PCB layout are Chips. Here is the IPC J-STD-001 guidelines for Chip packages. The main focus is the "F" dimension or the Toe solder joint goal.




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