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IPC-7351 SMD & PTH Reference Calculators
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Tom H View Drop Down
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Points: 5940 		Post Options Post Options   Thanks (0) Thanks(0)   Quote Tom H Quote  Post ReplyReply Direct Link To This Post Topic: IPC-7351 SMD & PTH Reference Calculators
    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.? 
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Muhammad Faizan Ahmed View Drop Down
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Points: 1 		Post Options Post Options   Thanks (0) Thanks(0)   Quote Muhammad Faizan Ahmed Quote  Post ReplyReply Direct Link To This Post Posted: 22 Sep 2023 at 11:00am
Kindly the excel sheet password
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Tom H View Drop Down
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Points: 5940 		Post Options Post Options   Thanks (0) Thanks(0)   Quote Tom H Quote  Post ReplyReply Direct Link To This Post 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.
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Aaronbat View Drop Down
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Points: 1 		Post Options Post Options   Thanks (0) Thanks(0)   Quote Aaronbat Quote  Post ReplyReply Direct Link To This Post 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
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stanleycayochok View Drop Down
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Points: 23 		Post Options Post Options   Thanks (0) Thanks(0)   Quote stanleycayochok Quote  Post ReplyReply Direct Link To This Post Posted: 26 Feb 2021 at 12:47am

Will definitely get the latest version.

Thank you Jeff for the detailed explanation.
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Jeff.M View Drop Down
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Points: 491 		Post Options Post Options   Thanks (0) Thanks(0)   Quote Jeff.M Quote  Post ReplyReply Direct Link To This Post 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.
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stanleycayochok View Drop Down
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Points: 23 		Post Options Post Options   Thanks (0) Thanks(0)   Quote stanleycayochok Quote  Post ReplyReply Direct Link To This Post 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     
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Jeff.M View Drop Down
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Points: 491 		Post Options Post Options   Thanks (0) Thanks(0)   Quote Jeff.M Quote  Post ReplyReply Direct Link To This Post 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.
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stanleycayochok View Drop Down
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Points: 23 		Post Options Post Options   Thanks (0) Thanks(0)   Quote stanleycayochok Quote  Post ReplyReply Direct Link To This Post 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?
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Tom H View Drop Down
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Points: 5940 		Post Options Post Options   Thanks (0) Thanks(0)   Quote Tom H Quote  Post ReplyReply Direct Link To This Post 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. 
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