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Soldering...what techniques do they recommend?

colporteur

I was behind a solder pencil today populating a few PCB's and got to thinking what solder techniques are still applicable today.

When I solder active devices like diodes and transistors I secure alligator clips to the device before soldering to wick away heat. I also solder devices with rows of pins by skipping every second pin, then cycle back to solder in the pins missed on the first pass.

This got me to thinking about SMD. No alligator clip on a diode in that environment. 

My question, is it still necessary to use the above techniques for soldering? I gained my skill in the early 80's. Technology changes so maybe I am stuck in the past.

  • 0

    Hi Sean,

    Soldering a lot of surface-mount with a small integrated-heater tip is a real pleasure. Quicker than through-hole, and easier in many ways because the irons do not need to supply as much heat on a small pad compared to all the metal in wire leads and through-hole pads.

    Good tweezers are essential, there were recommendations of tweezers from people on another thread. For a soldering iron, one of the USB soldering irons with integrated heater could be a low-cost option to get a feel for it all, before upgrading to a soldering station. The recent USB soldering iron I tried feels great on surface-mount, it's one choice, but others will be equally as good, for instance this one. I have only used mine for a week so I cannot comment on long-term reliability of it yet.

    There's some soldering technique ideas in the video below which I created as part of a RoadTest. The surface-mount portion of the video starts at time 8:45 in the video. Maybe some of it helps . You probably won't want to use the same method I use to solder the resistors at time 9:30, because it's a bit unorthodox. Most people put some solder on a pad first, it makes it easier. Anyway, you can see that with these small soldering irons, you can dip in-and-out with the iron within seconds, so there's no real chance of overheating components. 

    By the way regarding "When I solder active devices like diodes and transistors I secure alligator clips to the device", this is not necessary for through-hole parts any more. It was relevant for old semiconductor devices, but I can't think of any typical device that needs this any more (just mentioning this in case that's the reason for not using surface-mount).

    Also, a lot of surface-mount parts are the same size (or very similar ballpark) to through-hole parts. A head magnifier helps loads though.

  • 0 in reply to shabaz

    I don't have an immediate need to invest in SMD. 

    The techniques I use were to prevent failure of a component during install. I put headers pins on some Nano's and automatically soldered every other pin down one side then up the other. Then returned to fill in the gaps. A habit from replacing memory IC's on my Apple IIc.

    The small size of an SMD LED made me wonder about heat. I have used a solder pencil to attach wires to 402 size LED and they work. Flux and tinning is the secret.