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I have recently discovered that my AVR Dragon has a busted voltage regulator (see this). I am trying to remove the voltage regulator IC so I can perform the mod specified on that page, however it is a SON package with what looks like all of the pins under the chip.

Is there any way I can desolder this with a (very good) temp controlled iron? I have given it a whirl with some extra solder + braid with no luck.

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Sounds like a job for hot air. I've had success with removing components using a cheap craft tool such as a dual speed heat gun. You can also find some that you can make such as Hot air pencil for under $20.

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  • \$\begingroup\$ I can get access to an smd reflow heat gun but I am not sure of which parameters to use ie nozzle diameter, temp, etc. While I have been tinkering for a long time, I have never done anything like this before. \$\endgroup\$
    – jeremy
    May 13, 2010 at 12:05
  • \$\begingroup\$ s/reflow/rework/ \$\endgroup\$
    – jeremy
    May 13, 2010 at 12:28
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    \$\begingroup\$ Use a light touch, don't force the chip off. Experiment with some junk boards first \$\endgroup\$ May 13, 2010 at 12:32
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I've had good success using solder wick to draw off as much solder as possible. Then slip the tip of a dental pick under the side of the chip and gently pry up while heating the chip with a hair dryer. You might make a heat shield for the rest of the board by loosely covering it in aluminum foil with a cutout slightly bigger than the chip you're removing.

If it helps, solder melts around 218 C. It starts to melt below that, but it's fully liquid (above the "liquidus point") at 218.

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If it has these "exposed metalized features" shown in the PDF then you can probably get it off just by heating those up. I just put big solder globs all around the chip so that I can keep the entire glob heated at once, and when it comes loose, push it off. If the chip is already bad, you don't need to worry about ruining it. You might knock off nearby parts in the process, and if the PCB quality is poor, you might overheat and remove the protective mask? layer, but these can be dealt with.

Actually, if you don't care about the chip, just destroy it. :) When I blew up an IC with a solder pad under it, for instance, I cut off all the regular leads first to make the job easier.

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    \$\begingroup\$ I strongly recommend this method (paradoxically lots of solder is good for desoldering ;). You may also try using two soldering guns (transformer type are my favorite) to compliment the lots-of-solder but you should make it with only one. In this particular case you don't need the traces under the chip so don't worry if you destroy them a little in the process (just make sure there are no shorts after you are done). \$\endgroup\$
    – jpc
    May 14, 2010 at 0:37
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Removing leadless packages is easy with a good hot air station. To speed removal up, it helps to set the temperature high - I work around 420 to 480 deg C. Don't worry about overheating it: You're not often bothered with saving a dead part and a voltage regulator is cheap, anyway. Also, I set airflow rate to near maximum. I choose a nozzle which covers the chip entirely. If such a nozzle does not exist (i.e. the chip is too big - I had to remove a 208 pin TQFP once) I work around the edges of the chip until it shows signs of moving. If the nozzle does cover the chip, I just put it over, wait a few seconds and the chip will usually come off when you remove the nozzle. Remove it quickly or the solder may solidify and stick to the board.

Be careful with hot air, as it will often remove other components. 0603's don't stand a chance if exposed for more than a few seconds and then you'll have to solder more.

My hot air station is built into my soldering station, an Aoyue 968. But you can get a cheaper hot air only station. Dave Jones of EEVBlog did a review of one recently.

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