Any surface mount gurus here?

channelmanic

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I can't seem to make heads or tails out of some of these SOT-23 device markings... seems A9 can be a diode, a MOSFET, or a myriad of other devices.

Anyone have or know any magic around this?
 
hi res pics here might help us nail it down

If your camera sucks dont worry.. zoom it as far as it goes, get a big marnifying glass on a stand(lighted one even better), and take a pic through the magnifying glass. Works like a champ. Cam will be 6"-30 inches above the mag glass..

SOunds crazy but it works great. Thats how i got the token conversion pics done bitd.
 
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I don't think there's any magic, but there are several pages/databases of part markings out there. Here's a list of the ones I've got bookmarked:

http://www.ecadata.de/searchnew/
http://www.icphotos.org/
http://www.marsport.org.uk/smd/mainframe.htm
http://elektronik.googlecode.com/files/SMD_Catalog222.pdf
http://ordering.digikey.com/Documen...Content/MCC_353/PDF/MCC_SMD_Marking_Codes.pdf
http://focus.ti.com/general/docs/partmarking/partmarkinghome.jsp
http://www.s-manuals.com/smd
http://ganswijk.home.xs4all.nl/chipdir/n/smd.htm
http://www.maximintegrated.com/design/packaging/topmark/
http://ganswijk.home.xs4all.nl/chipdir/n/smdcode.txt

I personally try to get an idea of what the part is (if it has a silkscreen label, is it D, Q, U, etc... and look at what is connected to pins). Then I start looking through the databases/lists and seeing which ones match the package, and pull up the datasheets to verify.

Of course there are times that you can't find the part in any database. Then I try harder to determine what the part is, and search digikey for similar parts in the same package and manually look at the markings in datasheets. And sometimes you'll find a board with a LOT of parts from the same mfg (like ST, Microchip, etc), so I'll use that as a clue that it might be from that mfg.

For those wondering what we're talking about... check out this picture for example: http://www.icphotos.org/photo/ZUMTS17H.html . Notice that the marking on the device is T4H, which doesn't really help to figure out that the actual part number of the transistor is ZUMTS17H... unless you find something to help cross reference.

DogP
 
...For those wondering what we're talking about... check out this picture for example: http://www.icphotos.org/photo/ZUMTS17H.html . Notice that the marking on the device is T4H, which doesn't really help to figure out that the actual part number of the transistor is ZUMTS17H... unless you find something to help cross reference...

That's the exact problem. There is no standard set of markings on the smaller devices.

Resistors have codes on them that tell you what the value is.

Some capacitors have markings on them (but MANY do not)

Semiconductors that are too small to have full part #s on them just have cryptic codes that could mean just about anything. I found the label from the parts reel with "A9" on them and it turns out they were an "epitaxial switching diode" - a small SOT-23 part with 2 diodes inside.

It's crazy!

I'm trying to stock up on some small parts for repairs as it's a pain to try to find and pull tiny surface mount parts for repairs off a donor board. Eyestrain is bad after 5 minutes of searching boards with a magnifying glass for a 1/10w surface mount resistor - which is about the size of this "o".

RJ
 
I'm trying to stock up on some small parts for repairs as it's a pain to try to find and pull tiny surface mount parts for repairs off a donor board. Eyestrain is bad after 5 minutes of searching boards with a magnifying glass for a 1/10w surface mount resistor - which is about the size of this "o".

For Rs and Cs, I just spent a few bucks and ordered the standard preferred values in 0603, and a few of the most common of 0402. If you're careful, you can usually put an 0603 on either an 0402 or 0805 pad, and I really like them for prototyping, because they jumper across 0.1" pins nicely.

DogP
 
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