Confused about pad size
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=3248
Printed Date: 21 Nov 2024 at 9:23pm
Topic: Confused about pad size
Posted By: magnus.lictor
Subject: Confused about pad size
Date Posted: 20 Mar 2023 at 6:57am
|
LS, I am creating a footprint for an 0201 resistor and I am a bit confused about the pads for the generated component. The size of the 0201 is defined as 0.60mmx0.30mm, with a 0.03 tolerance. The terminal width = 0.15x0.30mm.  The visible grid is 0.01mm. The settings in the Footprint Expert fort the pad size are;  The placement tolerance is set to the default 0.025mm The generated part however has a toe value of 0.148mm. I do not understand how this value is calculated. The same applies for the side and heel value. I would expect it to fall inside the terminal. What am I missing ? Regards, Charles |
Replies:
Posted By: Tom H
Date Posted: 20 Mar 2023 at 8:35am
|
You are missing the package tolerances. The package tolerances are included in the mathematical model to determine the pad size. Make all the package tolerances 0.00 and see what happens. The Fabrication and Assembly tolerances are also used in the mathematical model to determine the pad size. Turn them to 0.00 to see the results. You can also turn the negative values in the solder joint goals to 0.00 and see what happens. ------------- Stay connected - follow us! https://twitter.com/PCBLibraries" rel="nofollow - X - http://www.linkedin.com/company/pcb-libraries-inc-/" rel="nofollow - LinkedIn |