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Adapting QFN-20 Package to Perfboard — Parallax Forums

Adapting QFN-20 Package to Perfboard

MikerocontrollerMikerocontroller Posts: 310
edited 2010-01-04 08:03 in General Discussion
· I'm ordering an Si Labs FM receiver chip.· It is available only in a QFN-20 package.· Can it be adapted to a perfboard using thru-hole mounting?· I did find QFN to SMT adapters but I have yet to learn SMT techniques.· Any ideas?· Thanks.

Comments

  • Phil Pilgrim (PhiPi)Phil Pilgrim (PhiPi) Posts: 23,514
    edited 2010-01-02 08:01
    Chekc out SchmartBoards: www.schmartboard.com/index.asp?page=products_csp. If you don't have any SMT experience, this is really the best way to go.

    -Phil
  • MikerocontrollerMikerocontroller Posts: 310
    edited 2010-01-03 20:53
    · Thanks for the link, Phil.· I will try the SchmartBoard.· I am confused by the socket, however.· All the depictions of the QFN socket· i·'ve seen look like industrial metal dies with pressure lock covers.· I thought they would resemble something like PLCC sockets.· Do QFN chips need to be "locked down" to stay in place?··Can a PLCC socket be used?· I have seen these offered in thru-hole configuration.
  • Phil Pilgrim (PhiPi)Phil Pilgrim (PhiPi) Posts: 23,514
    edited 2010-01-04 00:33
    If there's a socket for QFN packages, it's going to be a really expensive one designed for chip programming and testing. And, no, PLCC sockets will not work. The lead spacing is different, and they're designed for a different kind of package.

    The only practical way to use QFNs is to solder them in place. That's what the SchmartBoard is used for. Its advantage is that it fixtures the chip for you and provides troughs for the solder to make the soldering virtually goof-proof. Otherwise, you'd be learning to solder SMTs using one of the more difficult packages to work with.

    One final note: You're dealing with VHF frequencies. This means short, direct connections. So do the entire project on the SchmartBoard, if you can, rather than transitioning to perfboard.

    -Phil

    Post Edited (Phil Pilgrim (PhiPi)) : 1/4/2010 12:38:49 AM GMT
  • MikerocontrollerMikerocontroller Posts: 310
    edited 2010-01-04 01:23
    · Thanks again, Phil.· It makes sense now. When you mentioned the solder wells I began to understand how it would make SMT work easier.· If I were to use SMT components with leads (excepting the QFN, of course) the wells would also help position the part being soldered. ··In the case of the QFN there is no need to purchase a socket as the chip is soldered· directly·to the board.· Time to give it a try.
  • LeonLeon Posts: 7,620
    edited 2010-01-04 08:03
    Some people have managed to glue QFN chips upside down and attach wires to the pads. I wouldn't have any problems doing that as I have a microscope, but I'd just make a PCB for it.

    Leon

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