BGA soldering with a paint stripper and stopwatch

Having just received a shiny set of PCBs from the fab-house [Devbisme] needed a way to solder the main chip in place. It has a Ball-Grid Array footprint which is notoriously difficult to populate in a home lab. But he makes it look pretty easy and decided to share a video tutorial of the process.

The main tool he used is the paint stripper (heat gun) seen above. Since he didn’t have his own fancy reflow oven he made things work with the gun as his heat source. First he applies a generous layer of liquid solder flux to the BGA footprint on the board. Next he melts some solder onto the tip of his iron and uses it to tin all of the board’s BGA pads. Then it’s time for the critical step of positioning the chip. He uses vacuum tweezers to set it in place, and traditional tweezers to fine-tune its position. From here he heats with the paint stripper for two minutes, starting far above the board and slowly moving closer, with the reverse at the end of the soldering process. Once cool the board is cleaned with distilled water and blown dry with compressed air. After a visual inspection he finishes the application with a 30 minute stay in a 300 degree oven. We’ve included the video after the break for your convenience.

We’ve seen a similar technique used for replacing a chip on an already populated board.

Comments

  1. xfdrak says:

    Had to use a similar technique to repair my PS3 after it overheated and the heatsink tension pulled the GPU fromt eh MB.

  2. Whatnot says:

    Hmm, and how does he get the other parts on then, on both sides, with plastic components, that won’t work well with a paintstripper (heatgun) (and then a low temperature oven) does it? I’m not sure but I think that at least doing the reverse side will unseat the parts on the other side.

    Incidentally the writeup on hackaday says 30 minutes at 300 but the video says 200°F (93°C), which is not only a typo but you must mention the unit used, although as an excuse I guess you have to watch the video anyway if you want to emulate it.

  3. Alex says:

    That’s nice but at least one of the heating processes is redundant, either use the heat gun or the baking in the oven, but not both. Also 30 min in the oven seems excessive. But, yay, it worked, even though the process was overkill :)

  4. Almost all the other components were attached using a soldering iron. There was a small, leadless crystal on the bottom side that was attached using the heatgun. Not enough heat was dumped into the board to loosen the BGA on the other side when I did the crystal.

    Plastic parts can also be done with the heat gun. The epoxy bodies are made to go through reflow ovens.

    • Whatnot says:

      Interesting to hear, I always wondered and worried about it, and I had some regular connectors that melted with normal soldering so I wasn’t sure how these things were made. Thanks for the info.

  5. ash says:

    I worked at a contract manufacturer for 7 years. This is a manual process but very similar to how these types of devices are reworked.
    Initial soldering is done through a reflow oven but any rework involving removing and replacing a bga involved a heat gun and appropriate heat shielding to protect surrounding components.

    • Whatnot says:

      There is a difference between a heatgun in the shape of a painststripper and the one in the form of a hot-air soldering device, so are you saying a professional outfit did not shell out the $50-$100 it cost to get a real hot-air station?

      • ash says:

        My comment was meant to reflect the process he followed was very similar. The machine I was referring to was highly automated, had custom nozzles for a variety of BGA package sizes and was probably worth several thousand dollars if not 10’s of thousands.

  6. Lloyd says:

    Heats it for 2 minutes? How does that NOT melt the chip into oblivion?

  7. Grovenstien says:

    I managed to do something very similar reflowing the main chip on my Lipo charger. I did it with a pocket gas soldering iron using the exposed flame waving it gently over the chip. I could see the moment of solder silveryness and the charger now works fine!

    • Coda says:

      I have used pencil torches for this before, but they are much hotter than heat guns, and it’s very easy to burn the PCB, destroy components and melt packages and connectors.

  8. Coda says:

    Everyone should get a heat gun. I use mine for scavenging parts from PCBs (Through-Hole and SMD) quickly and efficiently, and these days I seem to repair an increasing amount of devices containing cheap and poorly soldered BGA parts from China. A very useful tool that can be had for around $10.

  9. Reggie says:

    These days you can pick up a cheap atten mains powered hot-air station for $40, for a cheap controllable method you can’t really go wrong.

    Build a stand so you don’t have to hold it and just increase the temp accordingly.

  10. messmaker says:

    A few months ago I picked up a hot air rework station on ebay for about $45. It was a really good purchase, as far as I am concerned. I have used it a few times to rework some chips on my projects. It is very easy to use and much quieter than I thought it would be.

    I have seen a few videos online where people are really aggressive with their heating – that is a good way to damage the components. The process presented here seems pretty tame.

    I haven’t had an opportunity ( or need ) to work with BGA components… but it is nice to see that it is possible to do at home.

  11. Ryan7777 says:

    probably not a bad idea to prebake your parts at low heat before soldering more-so than after the fact, if they have been outside their sealed anti-stat packaging for long. Some SMT parts have a tendency to draw moisture into their body. When hit with a reflow oven or rework gun that moisture can turn to steam and actually pop your chip.

    • Whatnot says:

      I would think that if you have a chip that absorbed moisture into its package you want it to pop rather than having something like that installed. Because a chip should not have that happen and be considered reliable.

      • Steph says:

        All chips and PCB’s absorb moisture. It just depends on how long they have been exposed. Industry standards prefer that you bake your components and PCB’s before reflowing them to prevent delamination (caused by steam pockets).
        As for the process, it can take 5-10 minutes to fully cycle the board through a reflow profile depending on part size. the best equipment heats the the PCB as well as localized around the part.

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