QFN Or MLF Soldering Without Solder Paste


Take a few minutes to watch this amazingly informative video on how to solder QFN or MLF components without solder paste.  The quality of the video and the information within is quite nice. Even if you don’t intend to work with these parts, you could pick up some tips for soldering with hot air.

22 thoughts on “QFN Or MLF Soldering Without Solder Paste

  1. Love it how the crazy yanks say “sodering”.

    Don’t they see the “L” in there?

    Have a look up what “sodering” or more to the point “sodomy” actually means using google.

    1. ‘Sodering’ means ‘soldering’ and has since at least the 1600s; in fact, it’s in the King James Bible that way, which suggests that if you limeys are using it differently now then that’s just a symptom of language rot.

  2. Now all I need is a new set of hands that don’t shake, and a microscope that allows me to use it while soldering at a price that doesn’t make small children cry.

  3. This video made me wonder: do they make ceramic or ceramic-tipped tweezers? And a quick google search shows that they do, so if you work with airflow soldering and the tiny parts that might be handy to acquire.
    The are also anti-magnetic (obviously) and anti-static even in most cases I gather, or as one site puts it:
    “They can be used for a variety of laboratory and electronic applications due to their heat and corrosion resistance, insulation and anti-static and nonmagnetic properties.”

  4. The key tool is the hot air, which is a Aoyue 6028 in the video. It’s a China-made tool that’s worked well for us considering the price. We sell it for $90, google to find it on amazon and others. You can get flux for $5-$20 depending on quantity, pens are around $5. Lastly, we normally do NOT use a scope during the process. These little QFNs have an amazing ability to snap into place–just get it close by hand.

  5. I do this pretty regularly at work, since we make qfn’s. I use a lab hotplate (with circuit boards bolted onto the sides to act as hand-rests so you don’t burn your hands on the top.) It works well at 200C. I put a dot of solder on the center of the DAP and put the chip on that, so I know that the DAP solder has reflowed when the chip drops down onto the outer pads. It works better if you use lead-based solder: enough capillary action to self-center the part. Also, Metcal sells one tip with an end radius of like 0.16mm, fine enough to touch the exposed metal on the sides of some QFN’s so you can reflow to the pad. Also also, you can often check continuity on individual leads by checking for the reverse body diode drop from a lead to ground. Also also also if you have a two-sided board, you can load the difficult parts on one side, then take a reasonably thick piece of aluminum plate and cut out holes where those parts live, and put the board face-down on the plate on the hotplate and load qfn’s on the topside as well.

  6. I do this with home-etched boards using a butane soldering iron with a hot air blower attachment. Much cheaper than a hot air rework station, just practice on some bare board so you can get a feel for how close to hold the iron without scorching the board.

  7. this is pretty precise. couldnt most people with soldering experience just wing it with a heat gun. i cant imagine destroying the pcb or components if youre a little off, unless you really dont know what youre doing.
    great video nonetheless!

  8. the other method is to hand apply solder balls using a blunt syringe needle like the ones sold for re-inking cartridges.
    interestingly they can be purchased by the thousand for not much money so if you are sufficiently determined reworking BGA can indeed be done.
    or soldering from scratch…

    takes a while though but if its a choice between scrapping a >$900 board or trying a $20 fix…

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