PCB Libraries Forum : IPC-J-STD-001 Gull Wing Leads and Solder Joints https://www.PCBLibraries.com/forum/ Wed, 15 Apr 2026 05:36:27 +0000 Mon, 27 Jul 2020 09:53:00 +0000 http://blogs.law.harvard.edu/tech/rss Web Wiz Forums 12.07 360 https://www.PCBLibraries.com/forum/RSS_post_feed.asp?TID=2587 <![CDATA[PCB Libraries Forum]]> https://www.PCBLibraries.com/forum/forum_images/PCBLForumLogo.gif https://www.PCBLibraries.com/forum/ <![CDATA[IPC-J-STD-001 Gull Wing Leads and Solder Joints : IPC did not accept the Proportional...]]> https://www.PCBLibraries.com/forum/ipcjstd001-gull-wing-leads-and-solder-joints_topic2587_post10857.html#10857 Author: Tom H
Subject: 2587
Posted: 27 Jul 2020 at 9:53am

IPC did not accept the Proportional Pad Stack concept. 

It was recommended but never accepted or approved. 

Everything (and I mean everything) in that Power Point presentation has been rejected by IPC. 

But PCB Libraries, Inc. implemented most of it in Library Expert (except the Proportional Pad Stack was thrown out because it was strictly based on Nominal Component Package Dimensions). 

However, the FED in Germany did pick up the Proportional Pad Stack model and published a book on it by Rainer Taube. 

]]> Mon, 27 Jul 2020 09:53:00 +0000 https://www.PCBLibraries.com/forum/ipcjstd001-gull-wing-leads-and-solder-joints_topic2587_post10857.html#10857 <![CDATA[IPC-J-STD-001 Gull Wing Leads and Solder Joints : i was looking at this document...]]> https://www.PCBLibraries.com/forum/ipcjstd001-gull-wing-leads-and-solder-joints_topic2587_post10856.html#10856 Author: david.vrtaric
Subject: 2587
Posted: 27 Jul 2020 at 9:19am

i was looking at this document  at page 38 https://dokumen.tips/documents/what-is-new-in-ipc-7351c-is-new-in-ipc-7351c-pcb-library-expert-fpx-library-multiple.html


]]> Mon, 27 Jul 2020 09:19:00 +0000 https://www.PCBLibraries.com/forum/ipcjstd001-gull-wing-leads-and-solder-joints_topic2587_post10856.html#10856 <![CDATA[IPC-J-STD-001 Gull Wing Leads and Solder Joints : Use the SOT-23 Calculator for...]]> https://www.PCBLibraries.com/forum/ipcjstd001-gull-wing-leads-and-solder-joints_topic2587_post10855.html#10855 Author: Tom H
Subject: 2587
Posted: 27 Jul 2020 at 9:12am

Use the SOT-23 Calculator for all Gull Wing leaded parts that have 3, 4, 5, 6 and 8 pins with various pin pitches. 

IPC-7351C is not released and it's not going to contain all the new features that we wanted. 

Whatever version of IPC-7351C you have is not correct (unless you're on the 1-13 Land Pattern Committee and got a Working Draft from IPC). 

You cannot manually do the math to calculate an accurate pad stack and its location. You need a calculator. 

]]> Mon, 27 Jul 2020 09:12:00 +0000 https://www.PCBLibraries.com/forum/ipcjstd001-gull-wing-leads-and-solder-joints_topic2587_post10855.html#10855 <![CDATA[IPC-J-STD-001 Gull Wing Leads and Solder Joints : Hi Tom,thanks for the fast replay.But...]]> https://www.PCBLibraries.com/forum/ipcjstd001-gull-wing-leads-and-solder-joints_topic2587_post10854.html#10854 Author: david.vrtaric
Subject: 2587
Posted: 27 Jul 2020 at 9:04am

Hi Tom,

thanks for the fast replay.

But how i can apply this calculator to SC70 package from the link?

Because i'm also looking at document what is new in ipc-7351c page 38 an fog gull wing pad length is nominal L + toe + heel ?

so for SC70 and nominal density = 0.35mm + 0.15mm + 0.2mm ?

Br.
]]> Mon, 27 Jul 2020 09:04:24 +0000 https://www.PCBLibraries.com/forum/ipcjstd001-gull-wing-leads-and-solder-joints_topic2587_post10854.html#10854 <![CDATA[IPC-J-STD-001 Gull Wing Leads and Solder Joints : No, this assumption is entirely...]]> https://www.PCBLibraries.com/forum/ipcjstd001-gull-wing-leads-and-solder-joints_topic2587_post10852.html#10852 Author: Tom H
Subject: 2587
Posted: 27 Jul 2020 at 8:32am

No, this assumption is entirely incorrect.

The Solder Joint Goals are in addition to the Manufacturing Tolerances and the Component Package and Terminal Lead Min./Max. Tolerances. 

We use the IPC-7351 mathematical model that is illustrated in IPC-7351B.

See the Surface Mount References Calculator for the math formula. 

It's in this folder on your computer: C:\Program Files (x86)\PCB Libraries\Library Expert 2019\Documents

File Name: PCB_Library_Expert_SMD_Reference_Calculator

]]> Mon, 27 Jul 2020 08:32:09 +0000 https://www.PCBLibraries.com/forum/ipcjstd001-gull-wing-leads-and-solder-joints_topic2587_post10852.html#10852 <![CDATA[IPC-J-STD-001 Gull Wing Leads and Solder Joints : Hi Tom,One question.I see the...]]> https://www.PCBLibraries.com/forum/ipcjstd001-gull-wing-leads-and-solder-joints_topic2587_post10851.html#10851 Author: david.vrtaric
Subject: 2587
Posted: 27 Jul 2020 at 4:45am

Hi Tom,

One question. 

I see the recommended Toe, Heel & Side solder joint goals from your tables (IPC-7351C Proposed Solder Joint Goal Tables for Least Density, but can you tell on what size do you apply these values from component datasheet? 

Eg.https://www.ti.com/lit/ml/mpds025f/mpds025f.pdf

I apply these values to E dimension mean values from 2.40 mm and 1.80 mm or to max value 2.40 mm and also what L value do i use 0.46 or the mean of 0.46 and 0.26? 

Br.
]]> Mon, 27 Jul 2020 04:45:16 +0000 https://www.PCBLibraries.com/forum/ipcjstd001-gull-wing-leads-and-solder-joints_topic2587_post10851.html#10851 <![CDATA[IPC-J-STD-001 Gull Wing Leads and Solder Joints : There is an exception to this...]]> https://www.PCBLibraries.com/forum/ipcjstd001-gull-wing-leads-and-solder-joints_topic2587_post10575.html#10575 Author: Tom H
Subject: 2587
Posted: 13 Jan 2020 at 5:52pm

There is an exception to this rule and that is the DPAK gull wing lead thickness can be 0.65 mm and the Toe should be 0.50 mm for the best Toe Fillet. 

The DPAK is a separate component family Terminal Lead Form in Library Expert with different Toe values than SOP, QFP, SOT and SOD. 

]]> Mon, 13 Jan 2020 17:52:24 +0000 https://www.PCBLibraries.com/forum/ipcjstd001-gull-wing-leads-and-solder-joints_topic2587_post10575.html#10575 <![CDATA[IPC-J-STD-001 Gull Wing Leads and Solder Joints : The Gull Wing lead is the second...]]> https://www.PCBLibraries.com/forum/ipcjstd001-gull-wing-leads-and-solder-joints_topic2587_post10535.html#10535 Author: Tom H
Subject: 2587
Posted: 26 Dec 2019 at 11:08am

The Gull Wing lead is the second most popular terminal leadform on most PCB’s.



There are two things that are important here:

  1. IPC-J-STD-001 does not mention any minimum Toe Goal solderfillet.
  2. The only comment for the Toe is that the Terminal Lead doesnot hang over the pad to violate the minimum electrical clearance. The Bdimension.

IPC-J-STD-001 does not put any emphasis on the Toe solderjoint goal. It’s as though it’s insignificant. The Gull Wing Terminal Lead canextend to the end of the pad and even slightly beyond the pad and still passJ-STD-001 acceptance criteria.

 

However, IPC-J-STD-001 does have several comments on theGull Wing Terminal Heel solder joint. The F dimension.

  • The F dimension for Heel Fillet for Class 1Fabrication is: Wetting is evident
  • The F dimension for Heel Fillet for Class 2Fabrication is: (G) + 50% (T)
  • The F dimension for Heel Fillet for Class 3Fabrication is: (G) + (T)

Here is an image from a Vishay recommended land pattern. The Terminal Lead Tip to Tip dimension = 6.20 mm and the recommended land pattern dimension for the outside pads = 6.248 mm. 

This meets the IPC-J-STD-001 solder joint criteria, but not the IPC-7351 solder joint goal criteria. 

http://www.vishay.com/docs/68969/si4925dd.pdf



Here are the IPC-7351B Solder Joint Goal tables 3-2 &3-3 for the Gull Wing Terminal Lead. Notice that the Toe and Heel solder jointgoals are the same value for every Gull Wing lead. Also notice that the differencebetween Most, Nominal and Least Density Levels are in 0.20 mm increments. PCBLibraries, Inc. believes that this margin between density levels is too steep.The Most density level is too large and has too much solder and the leastdensity level is too small and does not have enough solder.

Gull Wing affects the component families SOP, QFP, SOT, SODand DPAK. 



This is where PCB Libraries and IPC go our own separate way.IPC-7351B Nominal Density Level recommends a 0.35 mm Toe and Heel regardless ofthe component family, lead pitch and Terminal Lead Frame Thickness. The Lead-FrameThickness on a common DPAK is 0.65 mm but the Lead Thickness on a 0.50 mm pitchQFP or SOP is 0.15 mm. They do not require the same Toe value

PCB Libraries, Inc. believes that the Toe value should equalthe Lead-Frame Thickness to show visible wetting in the Toe solder joint. Hereis a simple image of this philosophy. 



PCB Libraries created an Incremental pad stack concept forGull Wing Leads based on Terminal Lead Thickness, which is primarily based onthe Terminal Pin Pitch.

 


PCB Libraries, Inc. believes that this margin betweendensity levels should be more subtle and swing 0.10 mm from the Nominal densitylevel to the Most and Least density level. If you compare IPC-7351 with theoriginal IPC-SM-782 land pattern standard that existed for 18 years, the SM-782standard was about 0.10 mm larger than the 7351 Nominal.

PCB Libraries, Inc. in conjunction with our top tiercustomers, created an Incremental pad stack table based on the Terminal LeadFrame Thickness which is derived from the pin pitch.


Download the Library Expert Excel spreadsheet Solder Joint Goal tables here – www.pcblibraries.com/downloads

Also, if you are a Library Expert user, the Solder Joint Goal table Excel spreadsheet is already on your computer in this folder: 

C:\Program Files (x86)\PCB Libraries\Library Expert 2019\Documents\Library Expert Solder Joint Goal Tables.xlsx

Here is an image of a real Gull Wing package with an adequate Toe Solder Joint. Not too big and not too small. 


]]> Thu, 26 Dec 2019 11:08:23 +0000 https://www.PCBLibraries.com/forum/ipcjstd001-gull-wing-leads-and-solder-joints_topic2587_post10535.html#10535