Hi Wendi and Don,
When we revised IPC-A-600 and IPC-6012, we put pointers in both of those documents to the new IPC-4781 qualification and performance specification for legend and marking inks (released in 2008). Prior to IPC-4781, there was no industry standard for legend and marking inks aside from an obsolete MIL spec.
This document is modeled after IPC-SM-840 for solder mask, and like that document, has requirements for adhesion to printed board laminate as well as solder mask.
We say in 3.2.10 of IPC-6012C that "Marking inks shall be permanent and shall conform to IPC-4781 or be as specified in the procurement documentation.
I agree with Don though, that we should examine this further within our two task groups. IPC-A-600H says the boards shall be inspected at no greater magnification than 2X for marking legibility. IPC-4781 says the following:
3.1.4 Legibility After marking is tested in accordance with the methods outlined in this document, excluding flammability, markings which are missing in whole or in part, faded, smeared, or shifted (dislodged) to the extent that they cannot be readily identified at not more than 3X
magnification, shall constitute failure.
Opps...
Best Regards,
John Perry
Technical Project Manager
IPC — Association Connecting Electronics Industries®
3000 Lakeside Drive # 309S
Bannockburn, IL 60015-1249 USA
+1 847-597-2818 (tel)
+1 847-615-7105 (fax)
+1 847-615-7100 (Main)
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www.ipc.org
-----Original Message-----
From: IPC-600-6012 [mailto:[log in to unmask]] On Behalf Of Dupriest, Don
Sent: Wednesday, June 16, 2010 1:55 PM
To: Listserv IPC-600-6012
Subject: Re: [IPC-600-6012] Legibility of Marking
Hi Wendi, I would say yes it applies to component marking (reference designators). Examples in 600 mostly reflect numbering (like traceability) but one example photo shows a component symbol. As to legibility; I would prescribe to if you can interpret the letters or symbol with 2X it is fine. However, this section probably could stand some more work. One thing we have noticed is 6012 does not specifically address adhesion for marking like solder mask is covered in 600 and 6012. It references a permanency requirement so one would assume tape test and/or solvent resistance would be applicable. But a tape test may be too difficult to pass for some really small feature sizes/designator letters.
Guess just another thing to add to the committee to do list.
C. D. (Don) Dupriest
Lockheed Martin - MFC
Advanced Manufacturing Technology
member of:
Production Technical Excellence Staff
Ph. 972/603-7724 fax: 972/603-9052
Email: [log in to unmask]
-----Original Message-----
From: IPC-600-6012 [mailto:[log in to unmask]] On Behalf Of Wendi Boger
Sent: Wednesday, June 16, 2010 1:05 PM
To: [log in to unmask]
Subject: [IPC-600-6012] Legibility of Marking
Everyone,
Does section 2.8 Marking in IPC-A-600 apply to Legend (component
mark)? We are increasingly seeing designs with very small legend
features causing discussions at final inspection as to whether they meet
the requirement for legibility. From what I understand legible means at
no more than 2x you can understand what the symbols are. Fussiness and
filled in holes in letters are allowed if you can tell what the letter
is.
Would appreciate some guidance on this.
Thanks,
Wendi
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