Playing with Cheap Heat Guns


If you have not heard of hot air rework, you are missing out! Hot air is my absolute favorite tool when working with embedded electronics. Hot air (checkout our hot-air rework tutorial) allows us to heat up multiple solder joints at once. This makes it much easier to remove problem voltage regulators, or turn a mis-mounted IC around, or replace a blown capacitor.

The problem is that most re-work stations cost $100-200. A high-end hot-air rework station will cost you >$1000. I cannot stress enough how great hot-air is, but you may not need to spend even $100!

http://www.sparkfun.com/tutorial/news/HeatGuns-M.jpg

A few people recommend these low cost embossing tools. The two pictured are Marvy Uchida (purple) and Mini Heat Tool Model: MT-50 (blue). At $20, you can’t really go wrong. But I tried them, and I wasn’t too impressed. They do work. You can remove ICs, but they have a very large nozzle. This will cause a significant portion of the PCB to heat up rather that the specific IC you’re working on.

I was able to remove a TFQP ATmega168 from an old Arduino-Skinny board I had laying around. So if all else fails, these guns help. But for everyone but the absolute beginner, I would not recommend them for real IC/SMD rework.

Now if you need to heat shrink - these things ROCK! I have been forced to use matches to heat shrink at home. One of the above guns may have fallen into my backpack and may follow me home.

Has anyone else found a better solution than a full hot-air station for SMD rework? A good low-cost solution that is completely DIY?


Comments 34 comments

  • A BernzOmatic Micro Torch (ST200T)- only about $11 is worth a shot.
    Besides being a torch, it has a soldering / hot blower attachment.
    These heat from a catalytic element so there’s no open flame.
    The soldering iron works surprisingly well, and would make a very good portable iron.
    I played around with the hot blower and found that it did a good job desoldering SMD parts. (Within minutes I had 20-30 parts I could hardly see and will probebly never use.)
    Since the hot air tip is so small, it’s pretty accurate and did not see any damage to the board. Worse case you have a new portable tool!

  • I envy you guys can have so much fun ,hope join you one day !

  • I use the Aoyue 852A hot air rework machine. It is great, I got it for around $80. Has a digitally controllable air flow and heat. They also have a hand held model, 8032, for $35 that I have not used but if $80 is too much money I guess you could try it.
    http://techgsm.com/Hand_Held_Hot_Air_Soldering_Station_Aoyue_8032,4380.html?_set_currency=USD

  • “You can remove ICs, but they have a very large nozzle. This will cause a significant portion of the PCB to heat up rather that the specific IC you’re working on."
    How about cramming on a Wilton cake decorating frosting tip?
    http://www.wilton.com/store/images/site_images/402-1%20_mpg.jpg

    • Yep, I immediately thought of cake icing tips. Found some cheap ones, but there’s no good way to affix them to the tip without welding or forming some kind of staple.
      The heat gun I found has a metal center core that is held in place by six plastic nubs. After about 90 seconds, even without the icing tip, is starting to soften the plastic nubs, and the smell of burning plastic begins. When I turn it off, I have to hold it upright until it cools, so it won’t slowly melt the nubs all the way down to the outer shell. And this is even written in the instructions for the device! Need to find some asbestos-like shims instead.

    • You can make a custom nozzle out of thin brass sheet. Make template out of stiff paper, transfer to brass sheet, cut [it’s pretty soft], bend to shape and braze using a MAPP torch and some thin brazing rod. A Butt joint will be fine.

    • I’ll give that a shot - the fish pump desoldering iron seems to almost get hot enough, but can’t get over the hump. My main interest in hot air work right now is recovering (and reusing) parts from the vast array of boards I have in the ancient computers in this room. I’ll be trying the skillet method for new construction… I’m naively hopeful that I won’t have to take one or two parts of my first PCB…

  • I went out and bought the stuff to make the one that PaulS (and I think someone earlier in the thread) mentioned, but it didn’t work for me. It’ll burn my hand an inch away, melt plastic, melt wax, and even melt solder on a spool (from 1/8th of an inch), but I might as well be pouring water on the parts I’m trying to salvage off a board, because it’s not delivering heat. The link with the instructions isn’t very specific with the ductile material, but I’ve tried stripped coiled wire (22 AWG), magnet wire semi-coiled/bunched up, aluminum mesh (crammed pretty tight in there), and nothing. It’s a 45 watt desoldering iron, it makes plenty-o-heat, but my 40-gallon tank air pump won’t deliver it, at any velocity I can achieve with the airflow regulator. Could anyone tell me what horribly stupid thing I’m overlooking?

    • The original “under $20” hot air tool that I made is good for new soldering with the board heated, and using solder paste. For -unsoldering- you might consider a paint stripping gun or the embossing tools as they force out a wider, hotter airstream.
      I get a lot of email about my original idea. Not everyone gets their version working, but for the most part the emails are positive success stories. The idea has spawned a series of imitations - some with unique variations, some that are identical (obvious from a recent post).
      I personally own some pro tools now, but the DIY one I made served me well. And I like to believe that it inspired people to air solder at a time that hobby-level soldering was mainly only done with pencil irons.
      Just for grins I went to Hobby Lobby and purchased an embossing hot-air tool to play with. It is great that more solutions are being discovered and that more SMT hot-air soldering is now within reach of the casual maker.

  • This is what I made, it might be the best DIY one out there.
    http://www.gideontech.com/content/articles/297/1

  • has anyone tried this from harbor freight?
    http://www.harborfreightusa.com/usa/itemdisplay/displayItem.do?itemid=41592&CategoryName=&SubCategoryName=
    It is a plastic welder and needs air source, but it small enough to be held like a soldering iron and it can generate really hot air. Costs about $39.
    I used it to remove some smd usb connectors.

  • While not cheap, I have used hot air and I have used Chip Quik. Chip Quik wins hands down. http://chipquik.com/ (Available at Digikey)
    How it works: Chip Quik is a combination of clear, smokeless flux and a low melting alloy. You apply the flux to the part to be removed. Then you apply the alloy. (The ally actually starts melting before you even touch it with the iron; it melts that low in temp.) Once all the leads of the part are wet by the alloy and it is sufficiently warm, the part will just slide off the pads. Then you just clean up the board and/or the part with more flux and solder wick.
    The low melting point means you don’t need to get the board nearly as warm and you don’t muck up the parts around it. The only drawback is that it won’t work well with BGAs if at all. (I’ve only ever used it with leaded/exernally padded parts.)
    I’ve even used it to remove parts from customer’s boards for failure analysis.

  • I have had great luck reflow soldering and desoldering/preheating difficult components (chips or connectors) with a purple one I picked up at CuriousInventor.

  • RPCElectronics: I am looking for an easy way to make some restriction nozzles and try to tighten up the air stream for small work.
    How about copper water pipe reductions? 1" to ¾", then ¾" to ½"?
    Just can’t solder the reductions together, but if you slightly oval one and then twist, that might work. Or drill a hole and add a rivet.

    • Just use a MAPP torch and some brazing rod. This higher temp “weld” will not be softened by the hot air.

  • As you found out, it’s easy to find an alternative to a prfession hot-air station, but most will heat too much of the board and it’s hard to localize it.
    I am actually using a Badger heat gun/paint remover. I use it by clamping one edge of the board in a really nifty board holder I have and heating from the bottom.
    The nozzle is roughly an inch in diameter and does heat up more of a board that I want, but it does a great job at heating up fast and getting the job done. I have used it mostly for doing re-work on larger parts like SMT GPS modules (Trimble Copericus mostly).
    I even use it to reflow small boards after I paste and pick and place them by hand. I put the board my board holder and then reflow by heating from the bottom.
    I am looking for an easy way to make some restriction nozzles and try to tighten up the air stream for small work.

  • We’ve been using the Weller #6966C at work for decades, ~$120. Gives 250 watts funneled into a 2" long 0.35" dia nozzle at hair-dryer air speeds. Works well on most parts, from SFF transceiver cans (might need two such guns) down to 0402 surface mount. We also use it for installing surface mount parts, especially those with a power pad. Protect neighboring parts with tin foil first, especially those that are small or thermally isolated. Dance the airstream about to distribute the heat evenly.
    If you can’t afford the Weller, consider taking a used hairdryer, add a nozzle, and slow the fan. Careful though, some of those can give nearly 10x the heat of our 250 watt Wellers. And not clear the materials they use will stand up to the higher temperatures, may need to add an interior metal shield plus insulation layer to the heating element chamber.

  • For SMD including BGA, even 1511 packages, the cheap target hot plate worked well for me if you control the temp. Go to Harbor Fright and get a $20 router speed controller to plug the $19 round Target hot plate into. It works great, and if you spend the time to characterize the temps vs the control dial, you can keep everything within allowable max temp specs. Using an Aluminum cover plate is a good idea too, especially for larger boards.

  • I’ve used one of these soldering iron/torch that are propane based… The problem with the torch is that you don’t get enough air pressure out of the nozzle. It works to remove parts, but soldering is almost impossible, unless your footprint is large enough and your component is properly aligned.
    With a proper reflow station you can see the part aligning itself with the footprint because there is enough air pressure to create an air cushion underneath it. This does not happen with a torch, you trully need air pressure…

  • hot-air guns, matches, lighters? don’t people use soldering irons any more?
    An iron is (IMHO) the best way to heat-shrink cable covers: it applies the heat just where it’s needed and nowhere elso. The rubber of the heatshrink has a high enough melting point that it doesn’t stick to the iron, nor does it melt to leave holes.
    So far as removing ICs goes, some 30+ years ago I made a DIY IC remover out of a piece of small-bore copper tube. It’s similar to the Antex desoldering bits, and has a tube that fits over the heating element of the iron and a flattened section of tube, which is the right size and shape to fit between all the pins of a DIP16 IC, to heat them all up simultaneously - works great and cost pennies.

  • Take a look here:
    This app note involves using very inexpensive hot air soldering equipment. Using the methods mentioned in this app note, surface mount soldering becomes easier for small shops and hobbiests.
    This is how I created the (probably) worlds-first air-pencil soldering iron for under $20. (Early 2001)
    http://www.usbmicro.com/odn/documents/ACC430664DD26DDE5986574AAA62775FDFF29EA1.html
    http://www.usbmicro.com/odn/images/B1C9C73E94A28C10155838F4F8F8EA14FEB163C5.jpg
    The “Under $20 (USD) Air-Pencil Soldering Iron” is made from a desoldering iron and an aquarium air pump.

  • Hi there!
    I have a very simple trick for any TQFP or simmilar parts rework:
    First: put as much solder as you can on the pins, clogging them to the point of being one solid solder row per side of the chip.
    Second: Use your firendly utility knife, and chop the top of the pins (slowly do multiple pass right were the pins come out of the chip).
    Third: The chip will come loose and pop/fall. If not, make sure you really cut all the pins, and pry it out.

    Fourth: Remove the pins with solder with your friendly solder wick.

    I tend to call this method the perfect complement of the solder-wick soldering method. I used this on two TQFP-144 last week, and it works like a charm.

  • This one on eBay seems to have a better nozzle than the one in Nate’s article: http://cgi.ebay.com/ws/eBayISAPI.dll?ViewItem&item=250370486939

  • I’ve been using a $40 ace hardware heat gun with electronic temperature control. Like he said above, the nozzle is a bit large. But I’ve thought about using pipe reducers or sheet metal to make some different nozzles.

  • I noticed you mentioned matches for heat shrink. I actually prefer a Bic lighter over a heat gun for small pieces. I’ve done thousands of connections that way, just use the blue part of the flame so it doesn’t leave burn marks. I can even do big pieces (1" diameter) but you have to be careful of the lighter flint getting too hot and burning your thumb.
    Learned the trick from my first boss in radio engineering, and have passed it on to several people since. Give it a shot!
    jon

  • My favorite are the Solderpro butane irons with the catalytic heat gun tip. This is oxygen free soldering. Find some nice techniques on:
    http://www.larsen-b.com/Article/291.html
    Adding something like the following no-cost hot plate for preheating, you need the heat gun just to push the temperature over the melting point:
    http://www.splashelec.com/catalog/pub/soldering/hotPlate.jpg

  • I can’t tell if it’s a smaller nozzle than you have there but I love my $20ish Wagner HT400 heat gun. It works great for SMDs. I think Wagner makes a variable temperature model now for a little more.

  • Nice find! Couple questions to help those thinking about modding one of these things..
    What size nozzle do you find yourself using most of the time? Do you ever use the square IC nozzles?
    Any chance you could post the mount diameter for the nozzles you sell?
    -p

  • I made a simple rework tool out of an older soldering iron. I saw the idea someplace but can’t find the link now. The idea is to blow air thru a hot coil of nichrome wire. Wind a coil of nichrome wire about the size of a pen spring. Attach a length of silicon tubing to a brass tube about the same diameter as your coil. One end of the nichrome is pinched between the brass tube and the silcone tube and the other is attached to the metal part of the soldering iron that held the heating element. The coil sticks out where the soldering tip used to be. Attach a wire to the brass tube and another to the soldering iron metal and connect it to a variable DC supply that can handle an amp or two. You will probably need some kind of heat resistant, insulating material to get the tubes fitting snugly inside the iron so it all stays together. Attach the other end of the silcon tube to the pump and adjust the power supply till you are getting really hot air exiting from the nichrome coil.
    It’s good for small parts but since the tip is so small it won’t do large chips.

  • One thing I have found a hot air gun useful for is removing parts from old boards. You need one that gets really hot and moves a lot of air. Heat the crap out of the solder side till the solder melts then give the board a sharp whack over a coffee can or something to catch the parts. A lot of solder comes off too but I’ve salvaged hundreds of thruhole and SMT chips, connectors, passives etc this way. You can remove SMT parts from the component side too but it requires care not to overheat the parts. Do this in a well ventilated area !

  • Neg want!
    I can’t help but think if you attached a metal nozzle to the front somehow, probably screws, you could make the airstream thinner for better reworking?
    –neg


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