PCB Libraries Forum : Package Symbols versus Mechanical Symbols https://www.PCBLibraries.com/forum/ Wed, 15 Apr 2026 04:15:52 +0000 Mon, 17 Feb 2020 07:07:08 +0000 http://blogs.law.harvard.edu/tech/rss Web Wiz Forums 12.07 360 https://www.PCBLibraries.com/forum/RSS_post_feed.asp?TID=2518 <![CDATA[PCB Libraries Forum]]> https://www.PCBLibraries.com/forum/forum_images/PCBLForumLogo.gif https://www.PCBLibraries.com/forum/ <![CDATA[Package Symbols versus Mechanical Symbols : Plated through mountingholes...]]> https://www.PCBLibraries.com/forum/package-symbols-versus-mechanical-symbols_topic2518_post10610.html#10610 Author: delovetsky
Subject: 2518
Posted: 17 Feb 2020 at 7:07am

Plated through mounting holes which are electrically connected need to be tested for.

This means it needs to reside with the net list for automated testing.

In Allegro a mechanical plated through hole will not allow a connection and would be voided within a shape.
 
]]> Mon, 17 Feb 2020 07:07:08 +0000 https://www.PCBLibraries.com/forum/package-symbols-versus-mechanical-symbols_topic2518_post10610.html#10610 <![CDATA[Package Symbols versus Mechanical Symbols : I&#039;ve confirmed that Allegro...]]> https://www.PCBLibraries.com/forum/package-symbols-versus-mechanical-symbols_topic2518_post10370.html#10370 Author: tjnash75
Subject: 2518
Posted: 12 Aug 2019 at 4:34pm

I've confirmed that Allegro mechanical symbols don't allow electrical connections, so at the very least plated holes can't be mechanical symbols and connect to a net.  How confusing...]]> Mon, 12 Aug 2019 16:34:44 +0000 https://www.PCBLibraries.com/forum/package-symbols-versus-mechanical-symbols_topic2518_post10370.html#10370 <![CDATA[Package Symbols versus Mechanical Symbols : I believe Allegro and OrCAD PCB...]]> https://www.PCBLibraries.com/forum/package-symbols-versus-mechanical-symbols_topic2518_post10369.html#10369 Author: tjnash75
Subject: 2518
Posted: 12 Aug 2019 at 10:44am

I believe Allegro and OrCAD PCB Designer both use psm and bsm files to delineate drawing types:
Package Symbol (.psm): Used for footprints such as SOIC20, BGA, QFP, and so on.
Mechanical Symbol (.bsm) : A generic card outline, mounting hole, tooling hole, board stiffener.
Format Symbol (.osm): A through D size page format, company logo, assembly/fab notes, cross section diagram, and so on.
Shape Symbol (.ssm): Creates a filled polygon (shape) used for custom pads.
Flash Symbol (.fsm): A symbol used to represent a thermal relief connection on a negative plane.

I don't believe the dra file is any different, and that the psm/bsm file is a binary file only used during placement.  

I experimented and there's definitely a difference, as changing the file extension broke my ability to place the symbol.  

You raise any interesting point about electrical connectivity, though. 

I wonder if mechanical symbols (from the tool's perspective) can still have electrical connectivity defined.  

I would think that a mechanical stiffener (e.g. a wedge lock) would possibly fall into the same category as a plated through hole, in that respect.
]]> Mon, 12 Aug 2019 10:44:15 +0000 https://www.PCBLibraries.com/forum/package-symbols-versus-mechanical-symbols_topic2518_post10369.html#10369 <![CDATA[Package Symbols versus Mechanical Symbols : There are Plated Through Mounting...]]> https://www.PCBLibraries.com/forum/package-symbols-versus-mechanical-symbols_topic2518_post10368.html#10368 Author: Tom H
Subject: 2518
Posted: 12 Aug 2019 at 9:42am

There are Plated Through Mounting Holes which are normally in the schematic tied to GND. 

There are Non-Plated Mounting Holes which are Mechanical. 

What's a .bsm file? Is that a Concept Symbol?
]]> Mon, 12 Aug 2019 09:42:46 +0000 https://www.PCBLibraries.com/forum/package-symbols-versus-mechanical-symbols_topic2518_post10368.html#10368 <![CDATA[Package Symbols versus Mechanical Symbols : I&#039;ve noticed when I create...]]> https://www.PCBLibraries.com/forum/package-symbols-versus-mechanical-symbols_topic2518_post10367.html#10367 Author: tjnash75
Subject: 2518
Posted: 11 Aug 2019 at 7:35am

I've noticed when I create items like mounting holes, they get created as package symbols as opposed to mechanical symbols.  

I'm not sure if I'm doing something wrong, or if this is the default behavior of the tool.  

If this is the behavior of the tool, why are things like mounting holes getting created as package symbols (.psm) and not mechanical symbols (.bsm)?  

Is this a bug or am I misunderstanding the purpose of mechanical symbols?

Thanks in advance!
Tim
]]> Sun, 11 Aug 2019 07:35:47 +0000 https://www.PCBLibraries.com/forum/package-symbols-versus-mechanical-symbols_topic2518_post10367.html#10367