Identifying SMD parts


I don't know if anyone has ever mentioned this or not. All my homebrew projects are 100% SMD unless I purchase a kit that uses through hole parts.

There are a couple of problems associated with SMD construction. One is parts falling to the floor or flying through the air and getting lost. Another is identifying parts that are later found. Or during construction and testing you place parts on the bench thinking you will remember later on to put them back in stock. Of course you can't remember what the part is a few days later.

The parts that can't be identified by sight are small semiconductors in SOT packages and capacitors. Capacitors can be identified with a tester but the semiconductors can't. About a year ago I developed a process to make the semiconductor problem easier. When I get a shipment from Mouser or Digi-Key I open the part package and look at the part labeling under the microscope. I then write the number on the outside of the package. That way if I find a loose part marked C145 or 6M, it will be possible to determine what the part is. I keep inventory sheets of all my parts and I also put the part label on the inventory sheets.

Some of the semiconductor manufacturers are starting to put the part labels on their data sheets. An example of this is the On Semiconductor MMBF5484/5/6 parts. The data sheet shows the parts as being marked 6B, 6M, and 6H. Hopefully it will become standard practice for all manufacturers in the near future to include this information in their data sheets.


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