soldering SMD devices



  • @frank freedman

    That Zephtronics link was quite informative and visual.

  • JRoark wrote: »
    Next time you are in town stop by a PC repair place.

    Great idea! Thanks. And I even know the main sales guy...*8)


  • davejames wrote: »
    JRoark wrote: »
    Next time you are in town stop by a PC repair place.

    Great idea! Thanks. And I even know the main sales guy...*8)


    Did I just most spectacularly and epically do a pratfall? (Let me guess: You're the salesguy?)
  • JRoark wrote: »
    (Let me guess: You're the salesguy?)
    No, no I'm not. But I really do know the main sales guy!

  • Hi Dave,
    May have already mentioned it, but you can get smd to dip coupons from TI, Adafruit and others. A few cheap 8 or 14/16 pin parts to practice with and you should be good to go.

  • @frank freedman
    :cool: :thumb:
  • Effort Update...

    The hot air pencil and solder paste arrived; tried them out today. After a bit of futzin' about, I was able to successfully mount a BS2 SSOP to my board. I can see that this is going to take some practice. :cool:

    Along the way, I had an opportunity to clean up some of the pins with the "chisel-tip/solder wick" method others have mentioned. I can see why some would go that route altogether.

    After debug of this board is complete, I'll upload pictures of the whole rig. Figured out a way to pre-heat the board that some may find interesting.
  • Oh yes please. Always interested in novel pre-heating
  • Yes practice. Hence my recommendation for smd to dip adapters and some cheap SMD parts if a part rob-bird with parts you don't care about was not available to practice on. As to your preheat method, I would like to see that for sure given the allowance draining destroying price on the Zeph preheat system.

    Got the ZT-2 delivered today!! Played a bit with it, it will need some practice and experimenting to get used to the smaller heat footprint as opposed to the cheaper air tools.
  • davejamesdavejames Posts: 4,007
    edited 2019-10-14 - 03:05:22, the "interesting approach" to pre-heating a PC board in prep for hot air soldering. (see attached image)

    The bulb is a 40W, reflecto-type mounted in a porcelain fixture w/pull switch. I have not measured the temperature of the board surface, yet. All I know at this point is the board is not cold and I don't really want to keep my finger on it after the light's been on for a couple minutes. In the end, heating the board does reduce the effort of the hot air from the pencil to melt the solder paste.

    The pencil unit is also shown in the attached image; $40 on Amazon. Build quality is fair-to-good. The manual is the absolute worst I've seen in terms of Chinese-to-English "translation". It definitely requires sitting down with a warm drink and spending some time de-tangling and deciphering.

    A close look at the BS2 SSOP shows decent soldering results; this was my first attempt. I'm confident that the remaining boards will look as good or better.

    Thanks again for all that took the time to pass on their insight.
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  • That's a good idea. I use a 50W MR16 spotlight for heating boards/chips to find heat related problems but never thought of using it to preheat a board area for soldering. I bet that would make unleaded soldering easier as well. Time to do a little experimenting.

    BTW, an MR16 (12V) or GU10 (120V) 50W bulb is quite a bit smaller and more rugged than most other bulbs and makes for a very compact setup.
  • It would be nice to add a thermocouple control to that, to hold the pcb at 150degC. And to check the heat spread and rate.

    I’ve had a Zephyrtronics ZT1 Air Bath since around 1997, after having seen their system demo at the Embedded Systems trade show. It was cheaper then than it is now, but still a big investment for a small shop. I don’t regret it. It gets lots of use for rework and for prototype builds and simply as a precise hot air source. Once a pcb is held at 150 degC, the hot air pencil quickly brings components uniformly up to the reflow temperature and the air bath brings them quickly back to 150.

    You can buy heat guns for less than $20 that have pretty good temperature control. The form factor is not great, but it should be possible to DIY a nice enough air bath. Forced convection works fast, and can cover a pretty wide area.
  • Nice setup! As a comparative example, the preheater assemblies on our 3 year old selective soldering machines are made up of quartz lamps, so essentially the same idea. When the board is nearing the desired temperature, the controller begins to adjust the duty cycle of the lamps, so you get a very slow sine wave style strobing effect. The newer versions of the machines use infrared.
  • Tracy AllenTracy Allen Posts: 6,513
    edited 2019-10-14 - 23:55:59
    The heat bath helps too in combination with Metcal rework tips and flux. The tip for removing a Propeller from a board is the SMTC1120. For a BASIC Stamp (SX48), the SMTC1121.
    Metcal soldering stations an be found on Ebay etc. I have a vintage MX-500 that takes two soldering pencils, one for heavier work (STTC and SMTC tips) and one (UFTC tips) for fine work. On the heavy side, here is one I got recently from Zephyrtronics (dba Ameritronics).
    It is 22mm long, 700°F, good for reworking connectors and flat packs. On the light end, here is my favorite UFTC tip, for getting in on fine pitch pins.
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