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Molded body polarity marking
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Tempest View Drop Down
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    Posted: 25 Jun 2019 at 8:16am
On a 3D step model, wondering why I'm not seeing a polarity mark on a molded body inductor, is the 3d step just not supporting this?It's been like this for a while just curious.

Thanks,
Paul
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Tom H View Drop Down
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Points: 5716 		Post Options Post Options   Thanks (0) Thanks(0)   Quote Tom H Quote  Post ReplyReply Direct Link To This Post Posted: 25 Jun 2019 at 9:30am
The Molded Body Inductor is bi-directional. 

It can be inverted during assembly. 

Can you provide the URL link to a datasheet that has a Polarized Inductor? 
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Points: 20 		Post Options Post Options   Thanks (0) Thanks(0)   Quote Tempest Quote  Post ReplyReply Direct Link To This Post Posted: 25 Jun 2019 at 9:46am
Hi Tom,

Some indicate polarity like the Panasonic part number ETQP4M220YFP, regardless as to if that is true or not.

The software does give the option for polarized inductor so I'd kinda expect a pin 1 indicator.

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Paul
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Points: 5716 		Post Options Post Options   Thanks (0) Thanks(0)   Quote Tom H Quote  Post ReplyReply Direct Link To This Post Posted: 25 Jun 2019 at 10:01am
Here is the Panasonic ETQP4M220YFP Molded Body Inductor. 

Download it here (much more Terminal Lead Detail) - 3D STEP

Here is what it looks like and I don't see any Polarity Marking - 
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Points: 20 		Post Options Post Options   Thanks (0) Thanks(0)   Quote Tempest Quote  Post ReplyReply Direct Link To This Post Posted: 25 Jun 2019 at 10:10am
Thank you Tom for looking this up, nice model.

I'm still wondering though, is Lib expert not supporting inductor polar marking and if not is it going to be.  If not maybe consider removing the option. 

Thank you
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Points: 5716 		Post Options Post Options   Thanks (0) Thanks(0)   Quote Tom H Quote  Post ReplyReply Direct Link To This Post Posted: 25 Jun 2019 at 10:16am
We only add Polarity Markings to packages that are polarized. 

Show me a polarized inductor and we'll add it. 

Otherwise, all inductors like all resistors, can be inverted during assembly. 

We do not want to confuse the assembly process with unnecessary polarity markings. 
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Points: 67 		Post Options Post Options   Thanks (0) Thanks(0)   Quote Ian S Quote  Post ReplyReply Direct Link To This Post Posted: 26 Jun 2019 at 1:24am
Following up on this subject here's some inductor polarity-related reading:


Ian
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Points: 5716 		Post Options Post Options   Thanks (1) Thanks(1)   Quote Tom H Quote  Post ReplyReply Direct Link To This Post Posted: 26 Jun 2019 at 6:48am
Ian - These are good articles. I wonder why the manufacturer's 3D models do't have a polarity marking. 

I've been involved in over 2,000 PCB layouts since 1974 and I've never added Polarity Marking on Inductors on the silkscreen Legend. 

I'm going to rethink this for the future. 

Thanks!
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We've been including a Pin 1 indicator on inductors when the manufacturer supplies it for the past few years. 

It was discovered during EMC testing that the polarity (a term I find inaccurate, should be more related to Pin 1 or the winding start pin) could be critical during PCB layout. 
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You should add a Pin 1 polarity marking on the silkscreen legend and the assembly drawing. 

This would help the assembly process, but also increase the performance of the PCB layout. 

I haven't seen a Pin 1 polarity marking on the mfr. provided 3D STEP models. 

If you have inductors lined up side by side, it's a good idea to point all Pin 1's in the same direction so that all the coil starting points are in the same direction. 
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