How-To: Make a surface mount soldering iron

Modding today's hardware often means moving or removing tiny surface mount components, and using a standard soldering iron feels about as effective as using a hammer to kill a fly. If buying an expensive reflow workstations seems like overkill to overclock your laptop, check out today's How-To where we'll build a simple reflow tool for under $20. Don't know what we're talking about? Well, you might want to click on anyway, it's an impressive feat nonetheless that might want to get you installing particular chips on particular game consoles (or not).

For today's How-To:

You'll need:

• Radio-Shack de-soldering Iron ($10)
• Small fish tank air pump ($7)
• Six to eight feet of vinyl fish tank air hose ($1)
• De-soldering braid or steel wool 
• Zip ties
  

Modify the de-soldering iron

The tip of the iron needs a little bit of work to efficiently heat the air flow. We lightly pinched the tip of the tip with our vice. Crushing the tip seemed to help direct the airflow, but we're not calling it necessary. Let us know what works best for you.

The next trick is to add some heat exchanging material to the tip of the iron. Cut off a length of de-soldering braid or get a small bunch of steel wool. The braid is copper, so it should conduct heat more efficiently.

Roll up the braid/wool and lightly stuff it into the tip of the iron. Don't push so hard that you restrict the air flow to much. The material will slow down the air flow slightly, and help radiate the heat of the iron into the air.  Gently re-install the tip, it's made of soft metal.

Get airflow to the iron

Since we don't have any heat resistant tubing, we used the suction bulb as a bulky, but simple heat insulator. Drill a hole in the end of the bulb with a 5/32 inch drill bit or something similar. The hole needs to be round for a good seal.

Insert the tube

Cutting the end of the vinyl tubing at a 45 degree angle will help a bit. Wet the end of the tube lightly and push the end into the hole you drilled in the bulb. Attach the other end of the tube to the outlet on the air pump. To clean things up, secure the airhose to the iron and along the power line with the zip ties.  Later we replaced the zip tie on the handle with some stylish red electrical tape.

Hot stuff

To use the gun effectively, allow the iron a sufficient warm up time without turning on the air pump. Once it's toasty, plug in the air pump and it'll be ready to go. In order to get a feel for the way the heat transfer works, we tried out our gun on a few workbench materials.

Heat shrink tubing

The tubing shrinks instantly with none of the burn marks we gotten with more primative methods.

Hot glue

If you've ever used a soldering iron to slice through some stubborn hot glue, you'll love this trick.
Hot glue is great, but sometimes it gets in the way. The heated air liquifies the hot glue without burning it.

Surface mount:

But what about actually soldering surface mount components? Our solder paste is on order, so we had to test it on a pre-assembled board.  It easily melts the solder joints on this chip.

Conclusion

Working with surface mount hardware has been a recurring challenge for us. We hate to admit it, but we may have actually resorted to crushing certain SMD resistors to enable some features in our hardware. Aside from the mad scientist look of our new tool, we can't wait to offer to mod someone's console with, um, parts from the fish tank. And that, friends, is reason enough to go through with this How-To.

Yes, they built one before over at gideontech. Ours won't melt the hose; Nope, we didn't read yours first.
[Thanks GideonX]

To really give credit for the earliest one we could dig up,  check out this one from 2001. [Via usbmicro.com]

If you don't like buying stuff from RadioShack, they rolled their own after sacrificing the microwave for science. [Via dansworkshop.com]

[ipod movies @ Mar 7th 2006 7:45PM]

I probably wont use it but its a great guide!

[kevin @ Mar 7th 2006 7:53PM]

sweet! i'm going to use this to reform the surfaces of plastic parts i hacked up for DIY modding in my car.

[Richard @ Mar 7th 2006 8:01PM]

Holy crap!
This is fantastic. I've been putting off buying a proper SMD station because they're so expensive.

Now I have no excuse to remove those crappy SMD green LEDs and swap em with blues!

[Steve @ Mar 7th 2006 8:02PM]

The easy way to remove SMD resistors is with two fine-tip soldering irons.

[nono @ Mar 7th 2006 8:06PM]

Pretty sweet!!! and I have the most of the stuff already...

[hg @ Mar 7th 2006 8:16PM]

Here's another example of ghetto surface mount - http://www.surveyor.com/cgi-bin/robot_journal.cgi/2006/03/07#020 - the skillet works great if you want to reflow an entire single-sided.

[Luis Antonio @ Mar 7th 2006 8:49PM]

how about puting in a pushbutton switch on the handle to control the air pump and just use it when needed ?

[Alan @ Mar 7th 2006 9:04PM]

Great idea! Cheap to build too :)

[stuart @ Mar 7th 2006 9:25PM]

Very nice guide! I will probably build one of these soon. Update when you get your solder paste!

[Zach Mauch @ Mar 7th 2006 11:05PM]

Wow, I'm a Senior at Oklahoma State University in Electrical Engineering and this may solve some of the problems that we've been having in building our circuits. The surface mount of the PICs (small programable processors) has been difficult to acomplish. This might greatly aid it.

Zach

[Adam Pennington @ Mar 7th 2006 11:05PM]

I understand the point of this, but if you can get access to a real rework station, it is very nice. I use a Metcal MX-500 rework system, and it is very nice to work with SMD components. Unlike a standard soldering iron, this heats up instantly, cools off almost as fast, and keeps constant heat while you're in contact with metal.

[GideonX @ Mar 7th 2006 11:46PM]

Looks like the same guide we posted last year, except with new pics:

http://www.gideontech.com/content/articles/297/1

[Will] Indeed, it's the same idea. Ours won't melt the hose thanks to the bulb trick.

[Gihad Joe @ Mar 8th 2006 2:43AM]

Is engadget not giving credit where credit is due?

http://www.gideontech.com/content/articles/297/1

[EdZ @ Mar 8th 2006 3:35AM]

This is great! I've got some video transcoder SMDs to solder, now I just need to find a source of solder paste in the UK.

[Jomo @ Mar 8th 2006 4:08AM]

I for one prefer the original guide over at gideontech...

[LS (UK) @ Mar 8th 2006 4:31AM]

Surely a hammer would be very effective at killing a fly?

[VBAjedi @ Mar 8th 2006 7:40AM]

Indeed, a hammer is very effective at killing a fly. The problem is that you often kill whatever's under/around the fly in the process!

[Daniel M. @ Mar 8th 2006 8:46AM]

Zach said: "This might greatly aid it."


wow, you sound purrtty smart!

[Spike @ Mar 8th 2006 9:34AM]

I owned these radioshack desoldering bulb irons before, the end where the bulb attaches doesn't get hot enough to melt the hose.

[Joe @ Mar 8th 2006 10:45AM]

God bless you Engadget.

[cordelia @ Mar 8th 2006 11:10AM]

interesting guide

[Todd @ Mar 8th 2006 5:12PM]

For the guy soldering PICs, I find that its easier to put extra solder on, then wick off the excess. It helps to have a fine tip too. I prefer to use the Metcal MX-500 at work, but when the wand cord breaks, the Weller irons we have work fine.

[Bill @ Mar 8th 2006 6:21PM]

Hey, that's great! I'm going to build one to go with my reflow oven...

http://articulationllc.home.comcast.net/sm0402.htm

Thanks!

[james @ Mar 8th 2006 6:30PM]

This is cool, but overkill for what someone said (swapping SMD LEDs). For discretes with only two contacts, you just put some tweezers on the part and use a regular (fine tip) iron to melt one side, then the other. Using the tweezers to apply a little upward force and you should only have to go side to side two or three times before it pops up cleanly, usually leaving pads with solder so you can you just reverse this technique to put in the new discrete.

[james @ Mar 8th 2006 6:34PM]

Also, look at www.schmartboard.com for a way of putting on tighter package parts with only a soldering iron.

[Raptor @ Mar 8th 2006 8:10PM]

Jesus, You guys maken all these things. Its like tring to invent toast all over again. JUST USE A HEAT GUN, AND SOME FLUX! the chip will come right off. No offence to this guy. Its all cool and stuff. But all that work when its already invented. Heat Gun.
Again sorry if I pissed any one off.

[cirano @ Mar 12th 2006 4:03PM]

Finally a good how to on making a SMD heat gun. Thank you, thank you. Now I can desolder all the components off the messed up old motherboards I have. Woo Hoo!!

[Jeff Walther @ Mar 13th 2006 2:31PM]

I agree with Raptor. A heat gun does the trick. Get one with adjustable temperature. I use a Milwaukee brand I bought at Home Depot with dial temperature setting. About 800 - 900F for 1 - 2 minutes takes off a chip.

If you're worried about surrounding components buy some cheap modeling clay and cover them with little snakes of clay. This keeps nearby SM resistors from blowing away.

If you impregnate the solder with Chip Quik first, then a setting of 600F will do the trick.

For resolder, carefully align the chip, tack down a couple of corner pins with a fine soldering pencil (e.g. 15 watt grounded from RS) then melt beads of solder all around the chip. Yes, intentionally form bridges. Heat the beads with a higher power pencil, such as the RS 40 watt pencil. This will insure even heating on all pins and pads. Then come back through with braid and collect the excess removing the bridges.

A small amount of care is needed to not remove too much solder. But it's really pretty simple.

I've removed and reinstalled 208 pin QFPs and 160 pin QFPs using these methods without a failure yet. I did use Chip Quik to lower the heat required for removal, in the case of these big chips.

[mike @ Mar 13th 2006 3:02PM]

You can use silicone tubing from your local hobby shop if you don't want to use the bulb. Just as for fuel tubing. It's used on RC aircraft, cars and boats. Cheap, flexible and high temp.

[anil @ Mar 14th 2006 7:04AM]

also try to have different nozzole attachment for small/big,sguare/rectangle IC with detachable/screwable collar mount.This will give uniform heat distribution on the component to remove,avoiding risk of pattern tracks of PCB being damaged.

[Karl @ Mar 15th 2006 5:15PM]

I knew I would find a use for that aquarium air pump I bought!!! Better solution than other DIY air-reflow guns I have seen.

[Jim @ Mar 18th 2006 8:50PM]

This just doesn't work as well as described. It just doesn't get hot enough. I tried it at least 15 times with different copper braid / steel wool configurations to no avail. A great idea and hack if it ended up working after spending the < 35 bucks. :-/

[Will O'Brien @ Mar 18th 2006 8:58PM]

Jim,
Please describe how it doesn't work for you. What kind of components? What kind of solder? My feeling with the device is that it walks a line of being hot enough. Did you let the iron pre-heat enough? Cutting the air flow for a period of time can get it hot enough. For full on smd soldering, I think it has maybe a 40% duty rate.

I tested it with several smd pieces that had been mounted with soldering paste, and it works decently.

More details please!

[Jim @ Mar 19th 2006 7:02PM]

I'm soldering both QSOP Led Drivers and 0402 Resistor Arrays. It may be that the solder I am using has a higher melting point, but it doesnt seem to flow the solder paste I use either. Granted, I only tried one kind of paste and one kind of wire solder. I am sure I let the iron heat up enough without the heat, I also varied the air speed by restricting the pump inlet. I ended up going with the flood and suck method I've seen online and have had some success, but I'd like to get the air pencil working somehow.

[Will O'Brien @ Mar 20th 2006 10:43AM]

Jim,
The writeup at usbmicro - linked at the end of the article suggests that preheating the board a bit helps. (placing it a toaster oven for a few minutes, etc.)

When I get a chance, I'll pick up an infrared thermometer and see just how hot I can get it. (probably next month, so I won't have that data too soon)

Did you try pinching the tip with a vice/vice grips or pair of channel lock pliers?

Since we're building a simple heat exchanger here, more surface area is better. I'll suggest putting some more steel wool inside the upper metal tube.

Wrapping the tip in a good quality high heat insulator would also help.

Finally, we could add some copper tubing that wraps around the tip/heating shaft and replaces the upper tube to provide a longer air heating chamber.

If all else fails...
I ran across a not about a hot air etching tool that micheals sells. It runs about $30 and may get plent hot already. However, I haven't had a chance to hunt down this lead. In the bay area at least, there's supposed to be a coupon for %50 of a purchase - yeilding it for $15.

You could probably try it, and if it doesn't get hot enough just return it.

[Nate @ Apr 28th 2006 10:43AM]

I built this one too, and it doesn't work for me either, it'll melt thin plastic, but that's about it. I made it to replace some smd leds, and it doesn't work worth a crap, I even left it to heat up for over 30 minutes with no air, and still not hot enough to melt solder, no matter how much braid I put in it. waste of $20

[Will O'Brien @ Apr 28th 2006 12:34PM]

Did you try preheating the board with the LEDs at all?

[skelotar @ Nov 14th 2006 1:24PM]

This doesn't work for me. As some previous posters mentioned, its only good for melting thin plastic. The problem is that a lot of heat is radiated away from the body of the soldering element through the metal on the iron. If that radiated heat could be contained, this might actually work.

[Will O'Brien @ Nov 14th 2006 3:33PM]

It seems to be a hit or miss thing. It's been a while since this how-to, but I'll make a suggestion - get some copper tubing or similar and wrap the heating element with it. Feed the air throught the tube - this could increase the preheat time sufficiently. (worth a shot if you're dying for it.)