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SMT variant of 2N3904 NPN transistor? Answered

Im looking for a SMT equivalent of a 2n3904 transistor. I found one on digikey that might be similar, the MMBT3904. Is this correct? Many thanks- Astroboy907



Best Answer 8 years ago

precisely. the 2n signifies the larger body traditional transistor package.

the mmbt is a surface mount sot-23 package.

It is best to design your circuit with a certain package in mind, then search for that package, and ensure the measurements match, most surface mount 3 leg packages are available for that transistor.


Answer 8 years ago

I actually found the exact part in eagle, so I dont have to design my own package (yay!). Though I might have to enlarge the pads for easier hand soldering. Luckily I have *some* experience with this after a texas instruments TPS61090 flop (project didnt even get to a pcb). Random thought, whats an ok package to hand solder? Im thinking 1206's, but I can get some 805s cheaper- but they're a lot smaller. Any thoughts?


Answer 8 years ago

really, with a good sharp tip on your soldering iron they;re all possible (my apostrophe doesnt work!)

1206 I did recently as current limiting resistors for an led project, and they were actually VERY fun to solder. 0805s are indeed much smaller but i doubt much harder using the blob one side, tweezer in place, melt, solder other side - method. Im not sure how difficult transistors would be, but their triangluar nature probably helps them suck into place easier. Keep the pads the recommended size - otherwise the part wont self-center as the solder melts.