3D STEP Model Polarity Dot Missing on SOICs
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=3545
Printed Date: 02 Oct 2025 at 5:50am
Topic: 3D STEP Model Polarity Dot Missing on SOICs
Posted By: m.elsayed
Subject: 3D STEP Model Polarity Dot Missing on SOICs
Date Posted: 23 Sep 2025 at 1:00pm
|
1-i need more detail by what means "some 3D missed dot polarity"? 2-what are the packages have this note? 3- how to correct this dot on 3D?  |
Replies:
Posted By: Tom H
Date Posted: 23 Sep 2025 at 1:43pm
|
This package is not a Metric Pin Pitch SOP. The Package Marking has a Dot and no chamfer on the body. It is a 50 mil (1.27 mm) pin pitch SOIC. These packages were introduced in the early 1980's when the package had a 45 degree chamfer all along the Pin 1 edge. No Polarity Dot. You need to know the difference between Imperial and Metric pin pitch packages. We have no plans on changing this polarity marking concept that been around for the past 35 years. Metric Pin Pitch SOPs come in these Pin Pitches:
The Imperial Pin Pitch SOIC Packages come in these Pin Pitches:
------------- Stay connected - follow us! https://twitter.com/PCBLibraries" rel="nofollow - X - http://www.linkedin.com/company/pcb-libraries-inc-/" rel="nofollow - LinkedIn |
Posted By: m.elsayed
Date Posted: 23 Sep 2025 at 4:02pm
|
Thanks Tom for your great support and help all time just if can add more details for packages have this concept other than SOIC and SOP? also is there any reference document i can read this point on it?
|
Posted By: m.elsayed
Date Posted: 23 Sep 2025 at 4:41pm
|
Thanks , Tom but just if can add more details for packages have this concept other than SOIC and SOP?
|
Posted By: Tom H
Date Posted: 23 Sep 2025 at 4:46pm
|
If you see a small outline package with a Chamfer along the entire side of the body where pin 1 is, than you know it's a SOIC. If you see a small outline package with a Polarity Dot where pin 1 is, than you know it's a SOP. Metric Pin Pitch SOPs come in these Pin Pitches:
The Imperial Pin Pitch SOIC Packages come in these Pin Pitches:
------------- Stay connected - follow us! https://twitter.com/PCBLibraries" rel="nofollow - X - http://www.linkedin.com/company/pcb-libraries-inc-/" rel="nofollow - LinkedIn |
Posted By: m.elsayed
Date Posted: 23 Sep 2025 at 4:50pm
|
Great Tom, But I'm asking you to explain for the below packages which I think it have same case.
 |
Posted By: Tom H
Date Posted: 23 Sep 2025 at 5:30pm
|
The SOT component families are Small Outline Transistors. This is a TI SOIC. No Pin 1 Polarity Dot on the 3D Model.  ------------- Stay connected - follow us! https://twitter.com/PCBLibraries" rel="nofollow - X - http://www.linkedin.com/company/pcb-libraries-inc-/" rel="nofollow - LinkedIn |
Posted By: m.elsayed
Date Posted: 23 Sep 2025 at 5:50pm
|
Can please have details for each package type in image like SOD, SODFL,SOFL,....SOJ, SOL,.... SOT223 (All package on mage) What pitch should have dot and what pitch shouldn't have dot like what you explained for SOP package. |
Posted By: Tom H
Date Posted: 23 Sep 2025 at 5:59pm
All SOT23s are metric pin pitch.
SOT223s come in various metric pin pitches and different pin quantities. All SODs are 2-pin packages. No pin pitch. All SOJs and SOLs are Imperial pin pitch and are on there way to becoming Obsolete. All QFPs are metric pin pitch. SOICs are Imperial unit pin pitch and they are the only component family with a Chamfer on the Body along the top edge of where pin 1 is. ------------- Stay connected - follow us! https://twitter.com/PCBLibraries" rel="nofollow - X - http://www.linkedin.com/company/pcb-libraries-inc-/" rel="nofollow - LinkedIn |
Posted By: m.elsayed
Date Posted: 23 Sep 2025 at 6:33pm
|
1-what about other packages? 2-according to reply all Sot will have dot,so please why mentioned note may there is not? |
Posted By: Tom H
Date Posted: 23 Sep 2025 at 8:08pm
|
SOT 3D STEP models don’t have a polarity dot because the component manufacturers don’t have one on their physical packages. Polarity Dots on component packages are intended for assembly shops to prevent inverting the component placement. Packages that have odd pins where it’s impossible to invert the assembly attachment. A 3-pin SOT23 does not need a polarity dot. A 4-pin SOT143 can’t be inverted. A SOT223 cannot be inverted. ------------- Stay connected - follow us! https://twitter.com/PCBLibraries" rel="nofollow - X - http://www.linkedin.com/company/pcb-libraries-inc-/" rel="nofollow - LinkedIn |
Posted By: m.elsayed
Date Posted: 24 Sep 2025 at 2:12am
|
Please provide more details for this note "Some 3D models may not support the polarity dot" it added for all the packages below  it will be great if have document explains this point so i can be aware by this concept
|
Posted By: m.elsayed
Date Posted: 24 Sep 2025 at 2:27am
|
also lease provide more details for this note "Some 3D models may not support the polarity dot"
it added for all the packages below  it will be great if have document explains this point so i can be aware by this concept |
Posted By: Tom H
Date Posted: 24 Sep 2025 at 8:14am
If the 3D Color panel in the Calculator has 'Primary Polarity' then the 3D STEP model will have polarity. If there is no 'Primary Polarity' button then there is no polarity dot.  ------------- Stay connected - follow us! https://twitter.com/PCBLibraries" rel="nofollow - X - http://www.linkedin.com/company/pcb-libraries-inc-/" rel="nofollow - LinkedIn |