Voltlog
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- Опубліковано 26 кві 2019
- $2 for 5 PCBs Any Color jlcpcb.com In this video we are taking a look inside a Bosch/Audi engine control unit. These things are always interesting to take apart for educational purposes because they are manufactured to be ultra reliable.
→I got this Bosch 4B2907401E ECU from here voltlog.com/y/6p14x
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#VoltLog #Teardown #ECU - Наука та технологія
The vent is used to equalize the air pressure between the inside and outside. Without it the device starts sucking water/moisture from the outside if the air pressure rises.
But how can the device start sucking water/moisture if it's hermetically sealed?
@@voltlog I assume that it is sealed when it leaves the factory. But after some years the seal and the connectors are becomming vulnerable.
It's called as DAE or PCE Pressure control element. It doesn't allow air inside but it can release air from inside
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Nice review/teardown. 👍
Useful video 👍 very good
Just recently open this Bosch. I have to apply Hot Air to soften the Seal and pry open the aluminum cover.
The big diode is for protection. In case you somehow connect the battery in the wrong way. That exact diode is used in many other electonic devices nowdays. I whorked for HARMAN where we built head units for cars(Audi, Maseratti, FCA).
The first chip you mentioned is the Atmospheric pressure sensor, since the ECU has torque and boost limiting maps based on atmospheric pressure.
How can it measure pressure if it's a sealed unit?
@@JamieVegasits not sealed, the black thing on top is vent
@@Skaude It's sealed, and the black thing is just a rubber flexible stopper, it allows atmospheric pressure to be detected by the unit on the board, without actual contact with air.
@@JamieVegas its a Gore Vent
The connector is not just a connector, but also includes a lot of RFI shielding and ferrite filter chokes and bypass capacitors in it as well, evidenced by the rear of it being a RF cage over the inside. Best to have this where the lead lengths to the outside are the shortest, so inculded in the connector housing by Amp. Hairy design work as your ceramic materials have to be precisely controlled as they do shrink during the firing stage from the green soft raw part, and those are also multilayer ceramic parts as well.
I saw the filtering passives on the pcb right next to connector pins but you are saying this connector also has built-in chokes and capacitors? Then it would make an interesting teardown, maybe in a future video.
@@voltlog Generally a lot of them do, often only on particular pins, with the extra components on the board being there for clamping purposes. Depends on the model though, if they have run out of board space then the connector becomes the filter space, or if they have need for extra filtering during EMI testing. Just pop off the steel shield and see if there is ceramic plating or ferrite plates inside. They typically are pressed over the pins before the bend, snug up against the back of the connector, with a grounding ring on the outside for the capacitor type.
The bottom parts are placed in the same direction so they can be wave soldered. You can see bit of a red glue under one of the chips. This saves even more costs.
Good catch, thanks!
@@voltlog
Also the extra pads after each IC on the bottom tells you the direction of the wave soldering. They are "solder thieves" and are there to prevent the last pins from being bridged.
VL, the rubber valve is not for condensation/humidity, the ECU has the MEMS atmospheric pressure sensor on the PCB(the AE4525) so it needs an opening to the exterior
I have worked with a lot of ECUs from Bosch and Continental. None of them had an internal pressure sensor but each had such a vent plug.
This could be true if the ECU indeed contains the pressure sensor but I haven't confirmed that yet.
You didn't mention anything about CAN bus communication controller or input/output. One of the crucial properties of the ECM and common failure in these units. Anyways this video is very useful though.
A couple of weeks ago I replaced a Mosfet (one of the ones in the left on the heatsink) of a similar ecu in a BMW motorcycle.
yup I would imagine Bosch would spin this design around for multiple types of vehicles.
Now I want to get a bad one (thinking it would be cheaper) and gut it and use the box for one of my projects.
This one was pretty cheap at $10 shipped. I am assuming it was functional.
Nice review. From what I've heard Infineon is not the major player anymore. Some of the manufacturers are favoring Cypress now.
It's about ASIL levels. Some Cypress products are ISO 26262 conpliant too. 😉
Back in 2012 I worked on a project where Bosch, CRF and Freescale designed a new ECU controller chip and safety certifications were a big thing. Regarding on how the agreement was made between the partners this new architecture was going to be sold by each partner to a different market with slight variations.
Infineon now is the biggest player,it just bought cypress,it was the second largest manufacturer of automotive semiconductors slighty behind NXP,now it is way ahead.
Very nice, Can you please show its software programs samples
Failed to note them EMC protective features. Array of through holes all round outer edges. All pins are fitted with bypass capacitors at front edge connector.
Good catch, thanks!
I think the vias at the edges are as much if not more for heat transfer between the layers than for EMI protection.
standard EMC management, heat transfers are the pafs an through holes of the pads under the driver chips
The extra copper on the PCB edges could be for heat sinking and also to create a faraday cage for EMC/EMI reasons.
I did this on a design I worked on. It will be interesting if the extra copper edges are capacitively coupled to the case, that’s what we did. But it can also be directly connected for EMI.
Thanks for the info.
AE4525 looks like an older generation mems pressure sensor that was used for altitude measurement.
From the part number it was most likely made by Aktiv-Electronic, Berlin
@@megatesla Thanks for the info!
Is it possible to replace it with a different one cause I can't find anything with this AE number ?
The purpose of the do218 diode is to burn the fuse in the event of a reverse polarity in the supply line
Design must survive reverse polarity WITHOUT damage. NO BLOWING FUSES!
ECU must survive reversed supply without damage. NO BLOWN FUSES allowed.
Depending on requirements that diode is added for the exact purpose of blowing the fuse ,that does not mean that other protection is not pressent for the ecu to survive the reverse polarity.
@@Brandon-wo2xj have been designing such ECU and am quite familiar with the specifications by the Auto manfsvturers. Blowing fuses is NOT allowed
I haven't checked but it could also be in series, preventing reverse polarity without any damage.
The vent is probably for barometric corrections otherwise a hermetic enclosure would disable the sensor.
kordta makes sense 👍🏼
likely Butyl for the seal.
thanks!
I haven't seen any conformal coating, is there any?
Also CAN bus transceivers are not shown.
Thanks
Most likely the CAN transceiver is the 8 pin IC (??43547) between the large Infineon controller and the TDK common mode filter (ZJY5-2). At least the pin-out looks correct.
And you are right, there is no conformal coating. It seems to be common practice not to apply conformal coating on these PCBs. Since the ECU is sealed, residual solvents in the lacquer can not evaporate and electrolytic processes can dissolve parts of the solder which then can cause short circuits between IC pins.
In general conformal coatings can create their own problems. Not in favour at all also costly messy manfacturing step
I was actually wondering why they didn't use conformal coating, but this certainly answers my question, makes sense now as that would possibly be unreliable long term.
My guess is the module is sealed, thus no need for conformal coating.
Hello,
Great video.
What's the size and pitch thread of 4 ecu case bolts?
thank you
15
I wonder if the processor can be reused for other duties? Remove it and have a new PCB board made for it.... There are literally tons of these things at the local motor dismantling yard and are also cheap...
I think the problem would be the development tools for that processor, compiler/IDE. Other than that it's a nice idea, this would be a great general purpose Digital/Analog control box.
Very cool to see one of these from the inside!
Why is it bad to have 100% coverage under those SMD packages ( ua-cam.com/video/x_9p3E5BVXo/v-deo.html )?
Did anybody notice green corrosion on pins of ecu on last part of video... this could be the culprit.
Where the Eprom chip?
Probably EPR/EPDM seal
Yup I think you are right!
4 megabit chip, or 4 megabyte chip?
hola , donde se encuentra el inmo ? gracias
TANTALUMS? EVIL!
why?
Not really, at least you know they will not fail for at least 20 years if properly specified and used correctly, while electolytics all are guaranteed to fail after some time. Tantalum if used well derated and current limited is not going to go bang, especially for quality manufacturers who run them conservatively.