PCB Libraries Forum : Confused about pad size https://www.PCBLibraries.com/forum/ Sat, 04 Apr 2026 20:03:29 +0000 Mon, 20 Mar 2023 08:35:28 +0000 http://blogs.law.harvard.edu/tech/rss Web Wiz Forums 12.07 360 https://www.PCBLibraries.com/forum/RSS_post_feed.asp?TID=3248 <![CDATA[PCB Libraries Forum]]> https://www.PCBLibraries.com/forum/forum_images/PCBLForumLogo.gif https://www.PCBLibraries.com/forum/ <![CDATA[Confused about pad size : You are missing the package tolerances.The...]]> https://www.PCBLibraries.com/forum/confused-about-pad-size_topic3248_post12924.html#12924 Author: Tom H
Subject: 3248
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. 

]]> Mon, 20 Mar 2023 08:35:28 +0000 https://www.PCBLibraries.com/forum/confused-about-pad-size_topic3248_post12924.html#12924 <![CDATA[Confused about pad size : LS,I am creating a footprint for...]]> https://www.PCBLibraries.com/forum/confused-about-pad-size_topic3248_post12920.html#12920 Author: magnus.lictor
Subject: 3248
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

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