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3D package generator gives wrong footprint for Chip LED

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Message 1 of 13
yaqoubdesign
531 Views, 12 Replies

3D package generator gives wrong footprint for Chip LED

When using a 3D Chip LED package using the package generator,  it gives a footprint which hugs the outline of the LED pads as shown below.  I did not see any settings which allows the footprint to be adjusted.   

The pads on the device are 0.2 x 0.8 mm.  The pad (footprint)  should be something like 0.6mm x 1mm .  

How can this be adjusted?  If I edit the footprint (which I  shouldn't have to do),  the 3D package becomes disassociated with the footprint.

 

Secondly, there is no indication in the 3D package generator to designate which side is the anode/cathode.  I checked with other types of diodes and they are ok.

Thanks for any advice   

 

Snag_19d0af3.png

 

 

12 REPLIES 12
Message 2 of 13

@yaqoubdesign Thanks for the concern.

 

The package editor is meant for editing 3D model or aligning 3D model over the footprint. The generated footprint is IPC compliant and it is not recommended to alter the pad sizes. However if you really want to edit the footprint you can do the same in Footprint Editor in Fusion Electronics Library and save a new version of the library which will prompt you to update the corresponding package in the library to be synched with the footprint. See the following screenshot.

 

Screenshot 2020-07-27 at 10.55.22 AM.png

 

The silkscreen normally indicates the polarity for LED. But the suggestion for showing A and K for pads is really appreciated. We will look into it. Thanks again.



Prasenjit Mondal

Principal Software Engineer
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Message 3 of 13

I hope you do so about the labeling A and C.  Please NOT "K" as you suggested...

 

Anyway,  the problem is that the footprint generated is incorrect I think.   Let me summarize again.

I used the package generator (Chip LED Generator) with basically the default settings:

Snag_26cc200.png

 See?  The generated footprint is just hugging the outline of the pads on the chip.  

When I download a 0603 package from SNAPEDA  (because they conveniently inform you that their footprints are IPC compliant I get the following for two different LED's.   In any case its not the same as from Fusion 360's package generator. 

Example 1 (a Dialight part, 0603 LED)   NOTE THE DIMENSIONS.  The Land pads are 0.83mm x 0.91mm,  total length = 2.41mm.

 

Snag_271806b.png

 

 

Example 2:  (a Rohm part 0603 LED)

 

Snag_273f718.png

 

So I'm asking someone to check if I am doing something wrong or what?

 

 

Message 4 of 13

@yaqoubdesign Sorry I meant A and C. Thanks for the correction.

 

The footprint is correct. Try to use same dimension in Fusion package generator which are used for other packages from ROHM and SnapEDA. For Chip package if you use body size with different min and max pad sizes also vary. Please try.

 

Note: Pad size might also vary slightly due to different component densities used to create the footprint across vendor. I am not sure about density table used from other vendor like SnapEDA even though it is claimed to be IPC compliant. We are following correct density table. 



Prasenjit Mondal

Principal Software Engineer
Message 5 of 13

I tried the chip generator with same dimensions required for the chip LED and I get  the following. You can see the footprint is correct- extending past the package itself, enough room for toe and heel etc..

Snag_741bb1.png

 

Now using the same dimensions for the Chip-LED package generator,  we get:

 

Snag_7f49f0.png

 

I measured the overall length of the footprint separately and it is 1.6mm,  same as "D" .   No toe room at all.    Can you please check again. How can this be correct?  It should NOT be different than that of the chip generator (first picture above) 

Snag_82c02b.png

 

 

 

Message 6 of 13

Note: component density differences are not the effect we are seeing here.  I have downloaded Library Expert Pro,  basically the experts on IPC rules,  and I have run it with chip-LED and chip-resistor at various densities.  There is very little difference, Unlike what we are seeing here with the Package-Generator.    

Message 7 of 13

@yaqoubdesign Could you please share the pad sizes in both case?



Prasenjit Mondal

Principal Software Engineer
Message 8 of 13

sure: for the chip LED the package dimensions are :

Snag_97a663.png

 D = 1.6mm,  A = 0.6mm,  A1 = 0.25mm,   E = 0.8mm,  L =0.3mm.   All of this as per previous message (see prev. message picture).  If you try these dimensions the footprint will be wrong (as far as I can tell)

 

For the chip package (non-LED),

Snag_9c6182.png

 D = 1.6mm,  A = 0.6mm,    E = 0.8mm,  L =0.3mm.  (same as per chip-LED and as per prev. message/picture)

If you try these dimensions you'll get a proper footprint. 

 

I appreciate your help in resolving this

 

 

 

 

 

Message 9 of 13

@yaqoubdesign Thanks for the details. Yeah it seems both footprint diverge while they should be same. We will look into this issue. Thanks for raising it. 



Prasenjit Mondal

Principal Software Engineer
Message 10 of 13

Thank you.

Message 11 of 13

just wondering if this got solved?

Message 12 of 13

@prasenjit.mondal 



Jorge Garcia
​Product Support Specialist for Fusion 360 and EAGLE

Kudos are much appreciated if the information I have shared is helpful to you and/or others.

Did this resolve your issue? Please accept it "As a Solution" so others may benefit from it.
Message 13 of 13

@yaqoubdesign It is resolved. Can you try in the latest Fusion release and let us know if you are still facing the problem or not. Thanks.



Prasenjit Mondal

Principal Software Engineer

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