marking pcb's

The post was a bit vague.....I don't see anywhere the claim that the boards are the same......I guess you have insider info since you find it necesary to correct..... Though, you might be correct!!

Only one problem....once you rout the board from it's frame...the notches are gone.....I have seen this time and time again when engineers are running tests.....You would have to notch the finished product....and most probably make it seriously ugly.....

On Wed, 17 Dec 2003 03:11:30 -0500, "zapp" Gave us:

Use the opaque epoxy as an ink. Make numerals. It can be scraped off, but where do they get *YOUR* brand to remark it with?

Since the notches do not involve any actual numerals, but are encoded by you with a limited set, they cannot decode them to copy or falsify them.

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Now we know they are all the same!....here is an easy way to identify each board....during the drilling process have a serial number drilled with one of the smaller holes in a land area....there are M codes that allow you to do this and it is a minimal engineering expense....it could be as easy as 1 to 50 ...they could easily do this for you...and hey, you can't forge that now can you.....Just assign a number to each student.....You may have seen card frames with lot numbers drilled into them...this is how some PCB houses keep board lots from getting mixed during the plating process where most of the "evils" occur..... A happy holiday season to all.....Ross

On Wed, 17 Dec 2003 11:11:32 GMT, "CWatters" Gave us:

They also have some with RTCs in them. The startup time, and serial cannot be duped, so hiding it physically is not required.

There are RTC chips out there that are serialized.

On Thu, 18 Dec 2003 02:23:08 GMT, "Ross Mac" Gave us:

It was obvious to me. It was later confirmed by the instructor.

On Thu, 18 Dec 2003 02:26:16 GMT, "Ross Mac" Gave us:

I guess that you've never owned or used needle files.

Small triangular notch, less than a half mm deep. Almost any encoding schema can be used, and one can even be made up.

All but crack proof. Colored fingernail polish can even be introduced, and the finished work varnished over to seal it in.

Nice, pleasing to the eye view of the individual PCB encoding.

The boards are already built as far as the SMT reflow part goes, if it is SMT at all. No frame involved. They are all already broken out, and get worked on individually by the students.

Notches?... We need some stinkin' notches!...

Badges?... We don' need no stinkin' badges!...

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Glad you're sportin' wood on this one.....He never stated it until late in the post!

On Thu, 18 Dec 2003 02:33:13 GMT, "Ross Mac" Gave us:

The boards are already made, and even if they weren't, they would still have to all be the same for each PCB on the palletized "frame"

Going through all of that trouble is kaka. Hell, the easiest way would be to have them laser marked after the PCB mfg part was finished. 3 seconds per PCB... max.

Kee rimany!

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No trouble at all.....what is your experience in this field???

What is then to prevent another student from sabotaging the serial on others' boards?

Get yourself a invisable marking pen that shows up under UV light. They are used for secrectly marking things for what ever purpose you have. Probably available at your local office supply store....Paul

On Thu, 18 Dec 2003 15:07:29 -0500, "Kevin G. Rhoads" Gave us:

The other students... and their guns. :-]

On Thu, 18 Dec 2003 17:36:51 -0800, "PJ" Gave us:

With as many UV sources in school labs, I'd think that it would get found out.

How are you going to keep it from washing away when the flux is cleaned off the board?

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Nice snip job!