What can you do if your circuit repair diagnosis indicates an open circuit within an integrated circuit (IC)? Your IC got too hot and internal wiring has come loose. You could replace the IC, sure. But what if the IC contains encryption secrets? Then you would be forced to grind back the epoxy and fix those open circuits yourself. That is, if you’re skilled enough!
In this video our hacker [YCS] fixes a Mercedes-Benz encryption chip from an electronic car key. First, the black epoxy surface is polished off, all the way back to the PCB with a very fine gradient. As the gold threads begin to be visible we need to slow down and be very careful.
The repair job is to reconnect the PCB points with the silicon body inside the chip. The PCB joints aren’t as delicate and precious as the silicon body points, those are the riskiest part. If you make a mistake with those then repair will be impossible. Then you tin the pads using solder for the PCB points and pure tin and hot air for the silicon body points.
Once that’s done you can use fine silver wire to join the points. If testing indicates success then you can complete the job with glue to hold the new wiring in place. Everything is easy when you know how!
Does repair work get more dangerous and fiddly than this? Well, sometimes.
Thanks to [J. Peterson] for this tip.
love that title: ‘basic skills’ for mobile phone repair
It’s too bad the world has come to this: mostly unfixable black boxes. My car dealership can’t even repair an EV charge cable chewed up by rabbits. How will today’s teenagers climb “from 0 to 60” with no ladder rungs in between so they can become tomorrow’s tech wizards or just plain tech-competent? In the 1950s and ‘60s there was a solid learning path for gear-heads, and same in the 1970s and ‘80s for computers.
YouTube
I understand where you’re coming from. And …
When I was a kid, I bought a couple transistors and built a thing. Today’s kids can buy a couple microcontrollers for $5 and build something. When they grow up – they can STILL buy Pi Pico 2 for $5 and build stuff, same as we did. They can just build better stuff, with better building blocks.
My daughter was writing code for fun, modding one of her games, when she was ten years old – and she’s not even a tech nerd.
My grandad didn’t have transistors when he was a kid – he could do relay logic. Maybe wind his own relay coil. I don’t think I missed out on much by using premade transistors. It just means I could build more capable circuits than my grandad did. And my daughter can build more capable ones than I did.
I think the trick is to have some understanding one level deeper than what you’re working with. If you’re using transistors, have a rough idea of how transistors work, so you can understand why they get hot. If a microcontroller is your building block, have some understanding of how work – what an “instruction” is and what 1MB means.
Very true!
I think it’s great that you can have an idea now, buy a few breadboard modules, slap something together, make the thing in KiCad, send to PCBWay and have your professionally made little four layer PCB, completely populated, for basically the BOM cost.
That wasn’t possible, even in the wildest fever dream, when I started doing electronics.
I can’t see anything wrong with that, whatsoever!
Oh, and now with management thinking AI is a suitable replacement for junior programmers, apprenticeship stepping stones are threatened too. (“Fire escape ladders” fully raised—no access from ground level.) Where are future software architects going to “cut their teeth”?
They’d lose a sale and open themselves up to all sorts of liability if they did plus the labor rate of a dealership tech means you’d probably be able to buy a new one for the same price or less.
People forget other people need to earn a living and dealerships need to cover their overheads.
Plus, if you’re a hacker, why didn’t you repair it yourself?
I think you are seriously underestimating human curiousity and persistence. One could have made the same argument for doing math by hand vs using a calculator. And understanding math by hand is important, but noone is doing that unless they absolutely have to. Does that mean that fewer people understand math? Not really, since there are more people capable of teaching it, because they dont spend their time doing precious calculations.
My personal bet is that younger generations are going to surpass us (the guy in the vid doesn’t seem perticularly old).
“One could have made the same argument for doing math by hand vs using a calculator.”
They still teach doing math by hand.
Most of the stuff I know about electronics and computers kids never get taught. I wasn’t taught it. I was forced to learn it because DHCP didn’t exist yet, and in order to hook a computer up at a university you needed these magic keys and man, they look suspiciously like bytes and how does this work anyway?
And let me be clear – I’m not a computer scientist or electrical engineer. I just know this stuff because I had to learn it in order to do stuff. The kids coming up in my field now don’t. And so they don’t know it. And it’s bad. Very bad.
This is not the same thing as “math by hand vs a calculator.” This would be like if no one ever taught multiplication tables or long division or multidigit multiplication and you were just given a calculator in grade 2 or something.
Old people thinking young people will be the death of us all are hilarious.
I am an EET in an Engineering R&D Lab so I have unfortunately had to do this type of work, it sucks.
I work with plenty of people with these skills old and young.
Digging into an IC or PCB is work to be avoided but we work on prototypes so sometimes we haul out the dental tools and put on our patience pants.
i wonder too. i think in some ways it’s not so different from how it’s always been though. there’s parts of the problem space that i understand well, and parts where i barely know a gloss of it. the windows through which we view technology are all changing but funamentally i think it isn’t changing…we view tech through a window. for example, the gulf between someone who understands low-level software and someone who understands high-level software may be growing but there’s always been that gulf in practice and always been people who straddle the gulf, and people who can’t see beyond node.js.
think about the demise of MSDOS…a lot of really arcane and valueless skillsets used to be broadly distributed in the population just because even casual users needed to compensate for the enormous weaknesses of that OS. now OSes are much stronger than DOS in so many ways, and casual users don’t understand anything about them and even many kinds of software developer don’t really understand them…but there still are people who understand them. even if they become a tiny fraction of software developers at large, they still exist and still, really, in very large numbers in an absolute sense.
This whole diatribe tells me you don’t understand the problem. It’s very, very different now. There are outright legally enforced barriers to learning.
As for the “demise” of DOS and “stronger OSes”, you clearly just don’t know what you are talking about. It’s still in use you know, and low level operating systems are in use everywhere. The “weaknesses” you don’t define are what exactly, quality of life additions like what you might find in a well customised busybox install?
there have always been legally enforced (and generally ineffective) barriers to learning.
the weaknesses of DOS are that it forced even regular end users to be aware of things like IRQs and TSRs and high memory. DOS still exists, but regular joes haven’t thought about those things in 25 years. it also forced a bunch of awareness on every developer that now hardly anyone (by proportion) thinks about. i don’t miss thinking about far pointers or EMS or modifying the global interrupt table. i don’t know how kids will learn without those hurdles but i suspect those limitations were not the sine qua non of learning
The places that still use older systems like that have at least one person on staff who knows the information required to maintain it, and if they’re smart they have that person take notes.
You don’t define “the problem” or what you mean by any of your second paragraph either, don’t act all high and mighty just because you see a massive emergency where others do not.
We have become a disposable society. It is terrible how much waste we produce. Things are not made to be serviced anymore. Just look at the ‘right to repair’ movement. Manufacturers don’t WANT you fixing things. There’s more profit selling new. Apple.. you pretty much need a new phone every 2-3 years..microsoft.. windows 11 mandate on machines that are perfectly fine doing what they need to do..
I get called on to fix things that..no one knows how to fix anymore. When was the last time you saw an electronics repair shop?
fwiw there’s a smartphone repair shop downtown in my small city. it’s been there about 5 years
Yesterday, two of them. Every town I’ve lived in has had one, with the exception of Salem, Kentucky, a town of 600 people last time I checked. I am also the guy that fixes things nobody knows how to fix anymore, which means there are at least two people that know how to fix things “nobody” can fix.
This is amazing but I’m curious how a keyfob SOC became so hot that the bond wires inside the IC package came loose. Was it some sort of manufacturing defect?
I also wonder how much a Mercedes-Benz replacement keyfob costs because this repair can’t have been cheap.
Some keys are scary expensive, like $600 and don’t forget you have to get the key and car to talk to each other as well which will almost definitely be a specialist or dealer job.
$600 keyfob + $200 programming
And if you have no working keys then they can’t clone a new one and it’s ECU replacement time. I was quoted $4500 for that.
NEVEN lose your last key!
ECU replacement is the manufacturer’s officially prescribed service method for dealers in this scenario but it’s not truthfully the only option. Avoid the dealership and call around for a locksmith that specializes in automotive. He’ll have the equipment to bypass the security and enroll additonal keys.
Grey market equipment to accomplish this task can also be readily purchased online – typically out of Eastern Europe.
Or, better yet, NEVER buy Mercedes-Benz.
Or a toyota… or a .. insert any manufacturer.
Toyota fobs are 600$ and most shops don’t have the software to recode the keys. Dealerships, sure.. for a massive price. My local locksmith.. nope.
Find me any manufacturer in 2025 who’s keyfobs aren’t ridiculously expensive.
It didn’t take especially long. You just need someone with “basic skills”.
Another example of how Chairman Xi’s horde of devious minions use the CCP’s cunning plans known by secret code names of “doing” and “superior skills” to steal from western companies their rightful fat profits.
Having done wirebond to die repairs myself, I am impressed.
What is all of this pretending state sponsored espionage isn’t a problem (and yes, that’s the problem, not your made up example)?
Actually, given the chip application, this may be a response to tampering.
Holy mother of repairs!! What’s next? Sanding all the epoxy and repair the transistors in the silicon itself?
Actually, there is very expensive equipment to do that. You can cut wires, add wires, and contacts inside the chip itself. It is quite expensive and fairly limited. Search for FIB on the web.
Don’t give them any ideas…
Ok but did the car start???
If this is an example of “basic skills” I can’t wait to see the advanced ones.
I get kind of sad when I see a video where someone calls it /welding/ … Which it is certainly not. It’s a very skilled worker, but it leaves me wondering, why on earth are they not using a cheap galvo fiber laser to open up the chip? It would be much more precise and safe.
American? In some places, that’s called welding.
Using a torch – to get a better view. With the key fob fixed, they can get in the car to open the bonnet and mend the other things.
In the US, welding melts the base metal; soldering melts a low-melting point filler and wets the base metal. While brazing does the same with a filler alloy similar to the base metal.
But also in the US, football is a game played with neither your feet nor a ball. It’s handegg. :)
Oh yes, why are they not using an expensive piece of equipment? Everyone has one laying around, don’t they?
Think about the cost of even a cheap decent laser compared to some sand paper.
Fiber lasers have come down in cost significantly (under $2k for one that can easily decap something like this chip). It really depends if that cost is more or less than the profit lost due to the failure rate of doing the decapping manually with a hand tool. I’d imagine the break even point would be if you do more than a handful of this type of repair a year.
Considering the repair was a success, I’m going to venture that the $2,000 cost would have been significantly more than the profit lost due to the failure rate of doing the decapping manually with a hand tool.