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Forum: PCB Design & Technology seven segment shaped four digit numbers on pcb


Author: guest (Guest)
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Hello

does anybody know what these "seven segment like" four digit numbers 
are, that can be found on many PCBs?

Here is an example of a raspberry pi 1 PCB bottomside, where such a 
number can be found printed inverted on the silk screen, right 
underneath the UL marking. (Bottom left, above D16) 
https://xdevs.com/doc/RPi/rpi3/rpi_oldb.jpg

I have been searching the internet for quite a while but found nothing 
reliable so far.

Thanks

: Moved by Moderator
Author: Georg (Guest)
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guest wrote:
> nothing
> reliable so far.

Not reliable, but may be: date of manufacturing, September 2014.

Georg

Author: guest (Guest)
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Yes, some kind of date code is also my closest guess so far. Somewhere I 
found mentioned two digits are for the year, and two digits for the 
number of the week in the year.

For the RaspberryPi 1 board this might even match, as I have one of the 
first ones from 2012 with a code 1233. Also the 1409 for 2014 week 09 
would still be fitting.

Other example numbers are 04.42 (this one has a dot in between) 0445. 
These could also fit, although I think the boards could be older than 
that.

However, I also have boards displaying 5343 and 3810. The numbers are 
all displayed in the same format, looking like seven segment digits, 
sometimes inverted, sometimes not, and in about the same size. 
Completely different boards from different companies and, quite probably 
completely different manufacturers. So the printed numbers seems to be 
some kind of standard, but these two board are definitely not from 1953 
and 1938 and as I'm not aware of any time travel activities yet, also 
not from 2053 and 2038.

Has anyone another hint?

Author: Lothar Miller (lkmiller) (Moderator)
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guest wrote:
> So the printed numbers seems to be some kind of standard
But not the information they contain.

> Has anyone another hint?
Its fairly easy: every company can print on their PCB whatever they 
want. You must ask them about their specific code...

Author: guest (Guest)
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Yes, it is fully clear to me that everyone can print on their PCBs what 
they like.
However, as I have seen this specific type of print on many different 
PCBs from different manufacturers, I thought there might be some kind of 
standard I have not found yet. Especially as the specific print of the 
four digits is in this seven segment style/font and not just standard 
text. For several of these prints the year and week format seems to 
match.

So I initially assumed there is some kind of rfc or normative document 
specifying the seven segment font format that is used. Even if it does 
not necessarily specify what the field actually contains. Or maybe this 
format even comes from a preset of a specific design software or exist 
for some historic reasons.

Again, any hints pointing me towards a source are greatly appreciated.

Author: Lothar Miller (lkmiller) (Moderator)
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guest wrote:
> So I initially assumed there is some kind of rfc or normative document
> specifying the seven segment font format that is used.
There ist not. Every manufaturer can use those digits at his own will. 
Also he can use any other markig style (barcode, labels, dots...).

> I thought there might be some kind of standard I have not found yet.
Tho only "unwritten standard" is that most of the manufactueres have an 
datecode of any kind on their PCB.
http://telcontar.net/KBK/Keycombo/help-dating.php (scroll down)
http://goughlui.com/page/6/ (in the mid)
But beside those you will find a lot of PCB without any datecode on 
them.

Attached you can find 3 datecodes from 3 different manufacturers of the 
very same PCB (manufactured for nearly two decades now). No one of them 
was requested to add anything on the PCB. They do it on their own to be 
able to track back production problems if necessary. The third one you 
could also rotate for 180° to get more "unclarity"...

> any hints pointing me towards a source
As already said: you must ask each specific manufacturer about their 
code.

: Edited by Moderator

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