Technology

I’ve only had to solder a couple of SMT chips, and though my attempts have worked out for me, it’s always been a combination of frustration and fear that I’m damaging the IC. John Gammell sent this video to me in response to one of my newbie attempts. In it, he shows how a pro approaches an SMT job using the “vertical drag” method.

It looks like he fixes the IC to the board, applies flux to all the pins, and then quickly drags a bead of solder back and forth over the pins. It’s pretty unbelievable how quickly and precisely he is able to do the job. Impressive stuff.

Professional SMT Soldering

7 thoughts on “HOWTO: Fast SMT soldering

  1. “I saw it on TV, and it looked so easy!”

    Anytime I’ve tried it I just get Solder Blobs on half the pins. I suspect he has Special Solder and Flux; anyone know exactly what he’s using?

  2. And I thought hobby electronics was dead the day most DIL chips were replaced by SMT ones. Thank you for the great video!

  3. The solder looks like production grade solder (63/37), and the flux looks like a fairly standard no-clean variety. All the consumables seem like standard, but of production grade.

    The secret to this style of drag soldering is the tip. The tip being used is a wave flow tip (spoon, or hoof tip) – a bevelled tip with a concave cavity. These style of tips are available for all major brands of stations. I use a Hakko 936 analogue single iron station with a small wave tip. The 936 is a nice, reliable, cheap ($100), and stable station and can compete with the two thousand dollar Pace unit seen in the video.

    Peter, if you look at the one minute mark you can see that the dual in line U21 is tacked at pins 1 and 8 in opposing corners. This is most likely done with a no clean flux gel, and and a fine conical tip. The gel has the viscosity and tackiness to hold the chip in place until it is soldered.

    I do all of my surface mount soldering in the same way, thanks to my IPC training.

    I must say, though, that this is a very nice workbench, except for the fume extraction arm.

  4. Nice video. Though it could have show the preparation used beforehand to tack on the IC’s before the drag soldering was done. I like to pre-tin a corner pad on the PCB and then with tweezers, solder the IC pin to that one pad, square up all the pins and tack the other corner

    I thought I would just point one thing out that I think needs to be made clear, is that your technique is fantastic for SOIC and SSOP devices, you really need to be careful with the QFP’s with the high density pins. When you are dragging your iron down the length of the pins you can easily start to bend them and then you are in a world of pain, as I’ve done once. It is better to drag with the direction of the pins so that you don’t bend them, it takes a bit longer than the videos but you have less change of bending any of the fine pins

    Also to all the hobbyist solders out there, you don’t need real fancy equipment to do any of this stuff either, pretty much any $30 electronics iron and basic tip will work nearly as well as it is all in the flux. It is the flux that makes it look so easy, so get that right and your most of the way there

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