Get Down to the Die Level with this Internal Chip Repair

Usually, repairing a device entails replacing a defective IC with a new one. But if you’ve got young eyes and haven’t had caffeine in a week, you can also repair a defective chip package rather than replace it.

There’s no description of the incident that resulted in the pins of the QFP chip being ablated, but it looks like a physical insult like a tool dropped on the pins. [rasminoj]’s repair consisted of carefully grinding away the epoxy cap to expose the internal traces leading away from the die and soldering a flexible cable with the same pitch between the die and the PCB pads.

This isn’t just about [rasminoj]’s next-level soldering skills, although we’ll admit you’ve got to be pretty handy with a Hakko to get the results shown here. What we’re impressed with is the wherewithal to attempt a repair that requires digging into the chip casing in the first place. Most service techs would order a new board, or at best solder in a new chip. But given that the chip sports a Fanuc logo, our bet is that it’s a custom chip that would be unreasonably expensive to replace, if it’s even still in production. Where there’s a skill, there’s a way.

Need more die-level repairs? Check out this iPhone CPU repair, or this repair on a laser-decapped chip.

[via r/electronics]

47 thoughts on “Get Down to the Die Level with this Internal Chip Repair

      1. What could be used as a reasonably suitable encapsulant ( let´s say, in an equipment that is not that costly ) ?

        Also, about the tooling ? Dremel with some microscopic bits ?

          1. Yeah, Dremel in like that. I am on the look for some 2nd-hand dentist tools to experiment with. I think some of those drill bits could be of the right size. Also, don´t remember where I saw it, but I mean to experiment with a laser burner for vaporizing some part of the encapsulation.

    1. Amen, brother!

      I’ve done this to re-purpose repairable spill damaged purpose-built E-POS equipment as test-rigs.
      As long as it is only some low power leaded chip that had their leads electro-etched away and it wasn’t caused by a 12v rail eating away at a 1.2v logic pin due to said spillage.
      Some such PCBs are quite robust… especially if the pads have all been gold plated first before soldering as the gold plating slows the corrosion on the board side to a salvageable state albeit with the copper under the delaminated gold coatings being exposed/tarnished.

      Opening the lead frame to expose a salvageable amount has saved things ranging from RS232 level shifters, LPC to IO/legacy controllers and all sorts. Also quicker to just throw a milling bit down in a chuck and expose the pads than wrecking a $400 mainboard attempting to replace the fragile-state component on fragile pads.

  1. Been there, done that.
    More than once, I lifted a QFP pin, to isolate it from the PCB track, and broke it, so I had to solder a small wire directly to the remains of the pin.
    Not rocket science.

  2. Thanks for posting this. Saw it on the same subreddit a few days ago. Based on the comments there and here, I get the impression that this sort of repair is simple and common for a small subset of electronics folks and completely foreign and amazing for the rest of us — in other words, exactly the kind of technique that should be shared with a wider audience!

    1. “in other words, exactly the kind of technique that should be shared with a wider audience!”

      Yes and no. It would be more lucrative for the one with the tools and knowledge but the difficulty level to mend the botch jobs of amateurs would be heightened to new levels.

      1. Well, some botched jobs can be just discarded, on the basis of the amateur destroyed it, or the prices for repairing it can be adjusted accordingly.

        But it is interesting to divulge the possibilities of this kind of repair so that people just do not dismiss something as unrepairable and just scrap the board. We have many cases here where people just want to throw away something because “It can´t be repaired” or “it is damaged and impossible to repair “, and I almost have to force them to show / bring me the boards to look at. And these are boards with SOIC chips, When I say I will just replace the chip, they go “That can be done ? “. Sadly, common people are getting too distant of the possibilities or realities of physical things….

        1. I dunno about the fancy tools. I’ll bet you could make this work with a file, a utility knife, a bunch of flux, flat flex, and a decent temp-controlled station. In other words, anyone with $100ish to spend and a decent bit of patience.

          1. Thing is… I’ve done it this way before… Also that chloro-something “plastic weld” stuff makes a good resin softener for making such a task like this easier. Work decided the stuff was a bit too potent (towards humans) and for health and safety reasons blacklisted it from getting ordered.

  3. I wonder if you could add leads to a package that can output signals based on some internal component of the die. Might need to have some strange coupling they leads to a driver circuit, but that could be interesting…

      1. Right, still… why not be elaborate? :-|)

        I was thinking automated rework station with custom IC repair or even custom IC’s made. OK, the later is overboard. Vapo deposition wouldn’t be so home brew easy with the kit. Maybe as an additional option however?

        Well… yeah… I’m more used to setting up machines for tools to be made and not the electronic IC’s. You know better at this kind of task/project.

        Excellent work and example. I never even had the thought of performing such a task.

  4. 20 years ago, the company I worked for contracted with another firm to repair an IC with a design flaw by rerouting a trace on the IC. This was with 0.6 micron technology; I don’t know how small are the features this sort of work can be done on.

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