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  • EEVblog #181 – Dead Bug Prototype Soldering

    Posted on June 21st, 2011 EEVblog 29 comments

    Dave show you how to solder a small 3 axis accelerometer LGA surface mount chip “dead bug” style onto a microcontroller prototyping board.
    This technique allows you to easily prototype projects using tiny SMD components designed only for reflow soldering.

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    27 responses to “EEVblog #181 – Dead Bug Prototype Soldering” RSS icon

    • When i first saw the youtube preview image i went “that is a accelerometer”. Probably cause i soldered one of those on a very similar way. I hate these impossible to solder packages.

    • another way around this could be to use a wii nunchuck – I bought a few cheap ones for less than $5 and you get I2C access to the 3 axis accell data (and a 2 axis analog joystic and 2 digital buttons) – handy for quick experimenting before playing with those nasty non hobby friendly packages. Nice dead bug work thoug Dave – an important and useful skill there.

    • The tip of the iron seems to cover two pads at once.. why would a smaller tip not be preferred to the chisel type?

      Also, when you later attach the flying leads to the same pad, wont the melted solder UNDO some of the leads here that go to the chip?

      • Karl (not that Karl, the other Karl)

        Heat transfer. And as you can see from the video the larger tip is really no problem. But with a small tip you would have to prod around like mad.

    • I wonder whether you could create a pcb with a hole that matches the package and have pads surrounding that hole. Then you just have to create solder bridges over the chip and pcb pads lying close together.

      Any ideas?

    • This technique reminds me of a wiring/prototype system I used in the 1980′s.It consisted if a pen like holder with a spool of wire on the top (much like a wire wrapping tool) The wire was like enameled copper wire that you soldered point to point. The insulation melted at the point of conact to make the joint. Wires of different colours could be bought. Can’t remember it name but it worked well and could be a winner for this sort of thing.

    • I suggest using magnetic wire instead. Radio Shack has a 3 pack that works great for these applications. The ends of the magnetic wire needs to be tinned to remove coating.

    • I struggled with this problem myself and here is what I came up with:
      http://www.starlino.com/reverse_surface_mount.html
      The idea is using a conductive pen it’s made of silver (warning: the cheaper carbon ones have some resistance) and bringing the device on the same level as pcb. I guess I would call the method “dead buried bug” .
      Nowdays however you can order a wide range of cheap smd adapters, a good source is http://www.proto-advantage.com

    • George Graves

      I’d like to think I could have designed, toner-transfered, etched and re-flowed a one-off adapter board in the time that it took you dead bug that….but I’m not positive I could.

    • I did pretty much exactly the same thing a while back (http://www.kerrywong.com/2010/04/16/interfacing-lis3lv02dl-using-spi-i/). What I found is that it is probably easier using a thinner wiring and a through whole protoboard.

    • adam lumpkins

      Dave how “Heat sensitive” is that accelerometer? Like allways GOOD JOB!!!!

    • Dave

      I think you may need to take some soldering lessons.

      Percy

    • Haha, love the magnification: makes even Dave’s relatively steady hands shake like he had OD of caffeine.

    • Hello.
      Good Technique.

      I did something very similar,for about one year.
      But i buid the board too.
      Handmade board.

      see the Pictures:
      http://metemedo.com.sapo.pt/fig.html

      Thanks.

    • All the pins look Au plated. If true flux isn’t really needed…

    • Do you clean up the flux after soldering ? Because afaik, leave it this way and it will ruing your board in a couple of months.

    • There’s a guy who does some of the finest hand soldering I’ve ever seen. Not exactly dead bug style but the he uses very fine pitch wires for his works.

      That’s his line following robot project:
      http://elm-chan.org/works/ltc/report.html

      There are many other projects under his domain.

    • On a related note, it’d be nice to have breakout boards with 0.1” pin headers for LGA (and such) packages that could convert such ICs to DIP that could be inserted into a breadboard.

      Routing the wires of such a breakout board in a way to de-invert the direction of the pins of dead bugs could be a nice touch.

    • Very nice demonstration. I’ve come across several similar packages that have a large thermal pad in the center for heatsinking. How would you go about applying a heatsink to a dead bug? A bit of copper foil bent up normal to the chip surface?

    • Bird sh*t solder is what we call that, if you worked for me i would be pulling you aside to talk about your poor soldering! Sure it will work but it’s nasty. Go get yourself a suitable tip and flux and try again. No clean BGA rework flux in a syringe will is much better suited to this job, you wont end up with those spikes of solder.

    • Out of curiosity, Dave, could you have used your hot-air rework station to achieve the same thing? – assuming you had a SMD adapter lying around which perhaps you didn’t.

      But thanks for the description – flipping the chip on its back is such an obvious technique – once someone shows it to you. :)

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