PCB Libraries Forum : IPC-7351 SMD & PTH Reference Calculators https://www.PCBLibraries.com/forum/ Tue, 14 Apr 2026 22:57:56 +0000 Fri, 22 Sep 2023 11:20:54 +0000 http://blogs.law.harvard.edu/tech/rss Web Wiz Forums 12.07 360 https://www.PCBLibraries.com/forum/RSS_post_feed.asp?TID=785 <![CDATA[PCB Libraries Forum]]> https://www.PCBLibraries.com/forum/forum_images/PCBLForumLogo.gif https://www.PCBLibraries.com/forum/ <![CDATA[IPC-7351 SMD & PTH Reference Calculators : The math formulas are in the Formula...]]> https://www.PCBLibraries.com/forum/ipc7351-smd-pth-reference-calculators_topic785_post13262.html#13262 Author: Tom H
Subject: 785
Posted: 22 Sep 2023 at 11:20am

The math formulas are in the Formula toolbar.

Why do you want the password to unlock the IPC reference calculator.? 

]]> Fri, 22 Sep 2023 11:20:54 +0000 https://www.PCBLibraries.com/forum/ipc7351-smd-pth-reference-calculators_topic785_post13262.html#13262 <![CDATA[IPC-7351 SMD & PTH Reference Calculators : Kindly the excel sheet password...]]> https://www.PCBLibraries.com/forum/ipc7351-smd-pth-reference-calculators_topic785_post13261.html#13261 Author: Muhammad Faizan Ahmed
Subject: 785
Posted: 22 Sep 2023 at 11:00am

Kindly the excel sheet password]]> Fri, 22 Sep 2023 11:00:06 +0000 https://www.PCBLibraries.com/forum/ipc7351-smd-pth-reference-calculators_topic785_post13261.html#13261 <![CDATA[IPC-7351 SMD & PTH Reference Calculators : There is documentation on your...]]> https://www.PCBLibraries.com/forum/ipc7351-smd-pth-reference-calculators_topic785_post13028.html#13028 Author: Tom H
Subject: 785
Posted: 13 May 2023 at 8:16am

There is documentation on your computer in this folder: 
C:\Program Files (x86)\PCB Libraries\Footprint Expert 23\Documents
  • Charter 1 Footprint Expert Console Options.pdf
  • Charter 2 Footprint Expert Calculator Options - Pad Stack Rules.pdf
  • Charter 3 Footprint Expert Calculator Options - Drafting.pdf
  • Charter 4 Footprint Expert Calculator Options - Fiducials.pdf
  • Charter 5 Footprint Expert Toolbar Icons and Menu Options.pdf
  • Footprint Expert Land Pattern Naming Convention.pdf
  • Footprint Expert Surface Mount Families.pdf
  • Footprint Expert Through-hole Families.pdf
Read them.

]]> Sat, 13 May 2023 08:16:47 +0000 https://www.PCBLibraries.com/forum/ipc7351-smd-pth-reference-calculators_topic785_post13028.html#13028 <![CDATA[IPC-7351 SMD & PTH Reference Calculators : Hello,I have the calculator but...]]> https://www.PCBLibraries.com/forum/ipc7351-smd-pth-reference-calculators_topic785_post13027.html#13027 Author: Aaronbat
Subject: 785
Posted: 12 May 2023 at 4:46pm

Hello, 

I have the calculator but I'm new reviewing this kind of stuff, from where I can get the information is question on the fields:
  • Fabrication Tolerance
  • Placement Tolerance
  • Toe Goal
  • Heel Goal
  • Side Goal
  • Place Round
  • Size Round
Some of them I don't know what it means. Cry
]]> Fri, 12 May 2023 16:46:30 +0000 https://www.PCBLibraries.com/forum/ipc7351-smd-pth-reference-calculators_topic785_post13027.html#13027 <![CDATA[IPC-7351 SMD & PTH Reference Calculators : Will definitely get the latest...]]> https://www.PCBLibraries.com/forum/ipc7351-smd-pth-reference-calculators_topic785_post11250.html#11250 Author: stanleycayochok
Subject: 785
Posted: 26 Feb 2021 at 12:47am


Will definitely get the latest version.

Thank you Jeff for the detailed explanation.
]]> Fri, 26 Feb 2021 00:47:56 +0000 https://www.PCBLibraries.com/forum/ipc7351-smd-pth-reference-calculators_topic785_post11250.html#11250 <![CDATA[IPC-7351 SMD & PTH Reference Calculators : You should try to get a more recent...]]> https://www.PCBLibraries.com/forum/ipc7351-smd-pth-reference-calculators_topic785_post11247.html#11247 Author: Jeff.M
Subject: 785
Posted: 25 Feb 2021 at 11:18am

You should try to get a more recent copy of IPC7351.
What follows is a direct quote from IPC-7351B, June 2010. Note the line for Smax.
(All the values in the Excel Reference Calculator match the example given in that document, allowing for rounding).
"Therefore, the calculations for ‘‘S’’ minimum and maximum dimensions are as follows:
Smin = Lmin - 2Tmax = 5.8 mm - 2 (1.27 mm) = 3.26 mm
Smax = Lmax - 2Tmin= 6.2 mm - 2 (0.4 mm) = 5.40 mm
Stol = Smax - Smin = 5.4 mm - 3.26 mm = 2.14 mm"

Section 3.4.1 discusses the reason for creating New_Smax.
New_Smax is ultimately used to produce Gmin.  Not Smax.


]]> Thu, 25 Feb 2021 11:18:07 +0000 https://www.PCBLibraries.com/forum/ipc7351-smd-pth-reference-calculators_topic785_post11247.html#11247 <![CDATA[IPC-7351 SMD & PTH Reference Calculators : Hi Jeff,There is no image on your...]]> https://www.PCBLibraries.com/forum/ipc7351-smd-pth-reference-calculators_topic785_post11246.html#11246 Author: stanleycayochok
Subject: 785
Posted: 25 Feb 2021 at 5:17am

Hi Jeff,

There is no image on your post.

I was referring to this Smax[RMS] formula in the 2005 IPC7351, please refer to attached image:



In the "SMD Reference Calculator for Excel" the formula is this: 
New Smax = Smax - (Stol -Stol[RMS])/2     


]]> Thu, 25 Feb 2021 05:17:04 +0000 https://www.PCBLibraries.com/forum/ipc7351-smd-pth-reference-calculators_topic785_post11246.html#11246 <![CDATA[IPC-7351 SMD & PTH Reference Calculators : I believe the formula you&#039;re...]]> https://www.PCBLibraries.com/forum/ipc7351-smd-pth-reference-calculators_topic785_post11221.html#11221 Author: Jeff.M
Subject: 785
Posted: 16 Feb 2021 at 11:10am

I believe the formula you're referring to (Smin + Stol[RMS]) dates back to the IPC-SM-782 document from 1993.  IPC revised this about 2005.
Please refer to IPC-7351B section 3.1.1 (should be page 11) shown as follows.
This example is demonstrated in our free SMD Reference Calculator for Excel.
]]> Tue, 16 Feb 2021 11:10:11 +0000 https://www.PCBLibraries.com/forum/ipc7351-smd-pth-reference-calculators_topic785_post11221.html#11221 <![CDATA[IPC-7351 SMD & PTH Reference Calculators : There is a difference on the Smax...]]> https://www.PCBLibraries.com/forum/ipc7351-smd-pth-reference-calculators_topic785_post11219.html#11219 Author: stanleycayochok
Subject: 785
Posted: 15 Feb 2021 at 9:14pm

There is a difference on the Smax[RMS] formula between IPC7351 and from the "PCB Library Expert SMD Reference Calculator.xlsx"


IPC7351 RMS Smax formula: 
Smax[RMS] = Smin + Stol[RMS]

Library Expert RMS Smax formula:
New Smax = Smax - (Stol -Stol[RMS])/2      
                

Both will result in a different output value. 
May I know why Library Expert used such formula?
]]> Mon, 15 Feb 2021 21:14:02 +0000 https://www.PCBLibraries.com/forum/ipc7351-smd-pth-reference-calculators_topic785_post11219.html#11219 <![CDATA[IPC-7351 SMD & PTH Reference Calculators : IPC-2221 and IPC-2222 are the...]]> https://www.PCBLibraries.com/forum/ipc7351-smd-pth-reference-calculators_topic785_post9685.html#9685 Author: Tom H
Subject: 785
Posted: 10 Jul 2018 at 7:35am

IPC-2221 and IPC-2222 are the only documents with through-hole pad stack info. 

IPC-7351C is stalled in committee and will not be released for another year or so. 

Every CAD tool defines Thermal Relief patterns differently. 

Library Expert has over 100,000 users worldwide and no one has ever complained about this issue in the past 6 years. We use best practice math that we have tested and tried in a CAD tool library since 1982. 

]]> Tue, 10 Jul 2018 07:35:11 +0000 https://www.PCBLibraries.com/forum/ipc7351-smd-pth-reference-calculators_topic785_post9685.html#9685