Silkscreen width |
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julien.meilhac
New User Joined: 18 Mar 2014 Location: Montpellier Status: Offline Points: 6 |
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Posted: 06 Nov 2014 at 7:02am |
Hello, 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
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Tom H
Admin Group Joined: 05 Jan 2012 Location: San Diego, CA Status: Offline Points: 5717 |
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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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julien.meilhac
New User Joined: 18 Mar 2014 Location: Montpellier Status: Offline Points: 6 |
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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
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Tom H
Admin Group Joined: 05 Jan 2012 Location: San Diego, CA Status: Offline Points: 5717 |
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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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julien.meilhac
New User Joined: 18 Mar 2014 Location: Montpellier Status: Offline Points: 6 |
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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
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Tom H
Admin Group Joined: 05 Jan 2012 Location: San Diego, CA Status: Offline Points: 5717 |
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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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julien.meilhac
New User Joined: 18 Mar 2014 Location: Montpellier Status: Offline Points: 6 |
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I use the Sample.fpx
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Tom H
Admin Group Joined: 05 Jan 2012 Location: San Diego, CA Status: Offline Points: 5717 |
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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:
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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julien.meilhac
New User Joined: 18 Mar 2014 Location: Montpellier Status: Offline Points: 6 |
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Thank you for your explanations.
Regards,
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