SMD Soldering not easy

Discussion in 'General Electronics Chat' started by tracecom, Nov 23, 2012.

  1. tracecom

    Thread Starter AAC Fanatic!

    Apr 16, 2010
    Today, I tried my hand at SMD soldering for the first time. The result looked OK until I photographed it, and then not so good. I used my Hakko936 with a 900-T-B tip and .032" solder. What do I really need in order to do better?

  2. Externet

    AAC Fanatic!

    Nov 29, 2005
    That is perfectly acceptable if was not overheated. Practice will do the improvements.
  3. bountyhunter

    Well-Known Member

    Sep 7, 2009
    As long as the leads are not bridged or shorted, you're golden.

    If you are using lead free solder, it will always come out looking terrible.
  4. thatoneguy

    AAC Fanatic!

    Feb 19, 2009
    It looks much better than other first attempts I've seen.

    Try 0.020 or smaller solder, and a flux pen to wet the pads before placing component, and on the pins after placing.

    The only problem I see is about 3x more solder than needed. Smaller diameter solder will help alleviate that problem, as will a separate liquid flux. The flux will help the solder wick under the leads to the board, leaving just a small fillet of solder from lead to PCB trace.

    Practice makes perfect, but good solder of small diameter will help a great deal. I'd suggest Kester or Chip Quick, leaded solder (63/37) makes it easier as well. Lead free solder + new to soldering will end up in cooked components.
  5. KJ6EAD

    Senior Member

    Apr 30, 2011
    Last edited: Nov 23, 2012
  6. John P

    AAC Fanatic!

    Oct 14, 2008
    That's not a bad job. But if the board contact pins are on 0.1" spacing, it looks as if the chip is an ordinary SO package, so it wasn't too challenging. Try the FTDI FT232RL chip, which is the world's favorite USB-to-serial converter chip. The package it comes in has 28 pins, with 0.65mm spacing (unless you prefer the QFN-32, which hasn't got pins at all). That's almost 40 pins per inch. And there's worse out there.
  7. THE_RB

    AAC Fanatic!

    Feb 11, 2008
    Your main problem is that the chip is misaligned, makign the bottom 4 pins a bit messy looking. The soldering itself is fine.

    It's good practice to hold the chip in place and tack one leg, then check alignment with a magnifier, and if ok then solder the rest of the pins.

    I've heard some people use blutack to hold the chip aligned good to get the first tack but I don't use it on small chips as the heat makes it go funny.
  8. bountyhunter

    Well-Known Member

    Sep 7, 2009
    There's an easier way I learned many years ago:

    Get some kapton tape which is an amber clear heat proof tape. Take a strip about 1" long and lay it on only one side of the device to be soldered, so one set of tabs (or tab) is in the open. You can lift the part using the tape (hold at each end) and "steer" it to align using the tape then when it's in place, tape it down to hold it while you solder the open terminal(s). Remove the tape and solder the other side.
  9. Blofeld

    Active Member

    Feb 21, 2010
  10. tracecom

    Thread Starter AAC Fanatic!

    Apr 16, 2010
    Thanks for all the input. I have checked out every link and watched every video, and I think I can do a better job next time. I tried to use the LMC7215 breakout assembly in a breadboard that I was building, and it didn't work. I am starting another thread on that subject. Thanks again to each of you.