PCB Rework and Repair Guide [pdf]

(intertronics.co.uk)

66 points | by varjag 2 days ago

5 comments

  • lnsru 1 hour ago
    Almost 30 years old. Old good times without BGAs and modern barely visible components. While some basics are still applicable the modern problems are not covered at all.
    • alnwlsn 42 minutes ago
      Provided you have good eyesight and steady hands, I've mostly found what happens as you get smaller is:

      - Heating becomes easier. There's no large sinks to take the heat away. It's also easier to overheat things.

      - You need finer tweezers, and don't drop them because if you do the tips will bend.

      - The solder's surface tension does more of the work. It feels a lot more like sticking together things with tiny droplets of glue. Having the correct amount of solder in the right place is critical.

      - Solder and flux become two separate things you have to care about individually

      - It is easier to burn yourself

      - learning how to brace your hand against something in a way that gives you very fine control. One reason soldering with an iron can be difficult is because your hand is so far away from the tip, like trying to write with a pen held by the end.

      • godelski 21 minutes ago
        When I started my first job a coworker encouraged me to learn how to solder SMDs and do "microsoldering". Like most people I thought I was going to need high precision and a much steadier hand. Probably like most people that learned I was impressed at how quick I picked it up. I think the hardest thing was learning about part "tombstoning" but that's not that difficult to deal with. I'm not going to say it is easier than soldering through-hole components, but I think for most people the mental barrier is much higher than the actual barrier.

        I now highly recommend learning it to anyone doing electronics. It's well worth the (small) time investment and makes things a lot easier, opening lots of doors. Even for a hobbyist you immediately get benefits. Everything becomes more compact, 2 sided boards are much more usable, and, of course, it opens up a lot of repairability (and recycling. Are you really a hobbyist if you aren't desoldering and reclaiming parts?).

    • Vexs 1 hour ago
      I don't think that modern boards are really repairable at all beyond component replacement- 4+ layer stackups being the big reason. If there's a way to do anything to those boards besides total replacement I'd be super interested to know.

      The techniques here are also way beyond basics I think- like, you look at most guides for repair and it's "idk just solder some bodge wires on there, here's what a good joint should look like"

      • dsvf 1 hour ago
        Andrew Zonenberg posted a Twitter thread a year or two ago where he fixed a missing PCB trace some layers down a PCB, with a stereo microscope, precision mill and very steady hands.

        Edit: here's the thread. It's a 6 layer PCB with a short on L5 that needs to be fixed from the L1 side.

        https://xcancel.com/azonenberg/status/1468825231225540611#m

    • varjag 1 hour ago
      It's great for working on vintage equipment, stuff that might need (and warrant) that kind of repair. Less so if you run a cell phone repair shop.
  • eimrine 28 minutes ago
    I have a problem of dismounting brittle SATA ports, maybe I just need more preheating but they are sitting really tight in the board.
  • amelius 2 hours ago
    Missing: how to solder a wire to the thermal pad on the bottom side of an IC. Assume there are components on the back side.
    • eimrine 38 minutes ago
      Isn't it just ground? If not, can you drill a corner of the chip? Most of chip material is just plastic.
  • donquichotte 1 hour ago
    Beautiful illustrations!
  • barfiure 3 hours ago
    Watch the PACE videos as well, they’re on YouTube and they also cover how to remove conformal coating and using different tools.