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Alignment pins/Mounting holes

Printed From: PCB Libraries Forum
Category: Libraries
Forum Name: Schematic Symbols
Forum Description: [General or a CAE specific issues / discussions]
URL: https://www.PCBLibraries.com/forum/forum_posts.asp?TID=2128
Printed Date: 21 Nov 2024 at 10:48pm


Topic: Alignment pins/Mounting holes
Posted By: dlveazie
Subject: Alignment pins/Mounting holes
Date Posted: 10 Apr 2017 at 12:13pm
I'm curious if there are any guidelines for symbols and footprints for parts (typically connectors) with alignment and/or mounting pins.

Firstly the symbol. Advised to show all? Only copper features? None? Seems wrong to not use any because more than likely they'll go to GND.

For the footprint, abbreviations (that obviously match symbol if shown) for these types of pins. AP? MH? WT? SHLD? 

Obviously there is no "one way" but if there are any suggestions, I'd like to hear them. I'm new to the librarian role and appreciate all the experienced opinions before me.

MH for mounting hole just feels like a screw hole. I like AP# for non-copper alignment pins and WT# for weld tabs but that's only because that's what Samtec calls them.


Replies:
Posted By: Tom H
Date Posted: 07 Sep 2017 at 5:31pm
There are no global standards on connector symbols, footprints or 3D models.. 

You should create your own guidelines and adhere to them. 



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Posted By: Matthew Lamkin
Date Posted: 17 Sep 2017 at 2:03am
I would add any hole that has a connection to it into the schematic, as a mapped pin within the library part. This would usually be a separate symbol if there are many of these, so that they can be moved to a corner of the schematic rather than clog up the main drawing area.

You can usually do this like a multi gate device is done in a library part.
There is no need to add alignment pins into the schematic, if it's not electrically connected - it does not "need" to be shown, unless there are overriding reasons for it being shown.

They have the same reference name as the main symbol, otherwise it confuses the reader - so do not use anything else. It is after all the same part.

I did this so that when checking the PCB for faults etc. the person doing this is fully informed of what is connected and what is not.

Otherwise they have to guess and assume and we know what trouble this causes :)


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