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Silkscreen width

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=1465
Printed Date: 07 Oct 2024 at 3:28pm


Topic: Silkscreen width
Posted By: julien.meilhac
Subject: Silkscreen width
Date Posted: 06 Nov 2014 at 7:02am
Hello,

In your components library, what thickness of silkscreen line you use ?

In my actual components library I use 0.2mm but in the IPC 7351C, the nominal silkscreen line width is 0.12mm.

Can you give me some advice ?

Thanks,

Julien


Replies:
Posted By: Tom H
Date Posted: 06 Nov 2014 at 7:12am

You can set the silkscreen line width and clearance value to whatever you want.

PCB Libraries doesn't sell CAD libraries, we sell FPX files with component dimensions.

Every User defines their own pad shapes, rules, drafting line widths, zero rotations (pin 1 location), solder mask swell and many more user settings.

The reason why IPC uses 0.12 mm (5 mil) is because the "Nominal" courtyard excess in 0.25 mm (10 mil) and if the line width and clearance are 0.12 mm the silkscreen doesn't push the courtyard excess out.

If your silkscreen outline line width and spacing in 0.20 mm (8 mils) then your placement courtyard will be pushed out 0.40 mm (16 mils).

The silkscreen should stay inside the placement courtyard excess.

Do you think we should add a new User Preference for "Allow Silkscreen Outside Courtyard"? Then the placement courtyard rule would override the Silkscreen Rule.





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Posted By: julien.meilhac
Date Posted: 06 Nov 2014 at 7:32am
Thanks for your reply,

I prefer use the nominal IPC7351C width, but all manufacturer are they able to manufacture this silkscreen width (0.12mm) ?

thanks,

Julien

Posted By: Tom H
Date Posted: 06 Nov 2014 at 8:52am

Most PCB Fabrication shops now use Ink Jet Printers to apply the silkscreen and it's very accurate.

Buy using corn hatch marks and thin lines saves Ink Cartridges.

But it's a User Preference. I talk to many companies and they are using the IPC default to achieve the highest packing density in their part placement.





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Posted By: julien.meilhac
Date Posted: 01 Jul 2015 at 5:25am
Thanks for your reply.

I have an other question.

On the library expert viewer software, for the footprint of the chip resistor "RESC1608X55" and on a most footprints, the solder mask and the land (pad) have the same dimension, why ?

Best regards

Posted By: Tom H
Date Posted: 01 Jul 2015 at 8:25am
What FPX file are you Viewing?
 
The Library Expert Viewer is used by our LE Pro customers to share their personal library data and rules file with co-workers and customers. That's all it's used for, to allow others to freely View your personal library data.
 


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Posted By: julien.meilhac
Date Posted: 01 Jul 2015 at 8:28am
I use the Sample.fpx

Posted By: Tom H
Date Posted: 01 Jul 2015 at 8:42am
OK, I see what you are doing now.
 
The IPC-7351 format is to have the Pad and Masks 1:1 scale of each other and then allow the User to control the Paste Mask reduction and the Solder Mask to whatever values your company has set up.
 
Solder Mask is a Preference setting and every User creates a custom Preference file with the Mask swell of their choice.
 
The only thing the FPX file has is:
  1. Component Dimensions (for the IPC Calculators)
  2. Mfr. Recommended Pattern (for the FP Designer unique parts)

There are several hundred rules in Preferences to allow every user the opportunity to create the footprint that meets your personal corporate guidelines. Pad Shapes, Drafting Line Widths, Clearances, Solder Joint Goals, Masks, Origins, Rotations and on and on are in the Preferences file.

And in V2016, there will be more Preference rules.


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Posted By: julien.meilhac
Date Posted: 02 Jul 2015 at 12:09am
Thank you for your explanations.

Regards,


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