Dismiss Notice
Join Physics Forums Today!
The friendliest, high quality science and math community on the planet! Everyone who loves science is here!

Q: What's in the phone?

  1. Mar 8, 2019 #1

    Andy Resnick

    User Avatar
    Science Advisor
    Education Advisor

    During winter, when I can't take pictures of the stars, I tend to take pictures of decapsulated computer chips. As my technique improves, I'm able to find things that had been destroyed in earlier attempts- for example, I can now decapsulate MEMS devices leaving intact the suspended Si membrane, which makes for some good in-class discussions. Most recently, while processing an old iPhone, I've uncovered a bunch of 'things' that I hope PF-ers here can help identify.

    First up are small ICs that seem to be printed as thin films on quartz or sapphire- not sure which:

    c447edfc-6a3e-4d7a-8230-1ce3372dcf3e-original.jpg

    76d71adf-4741-4bec-b8a9-d8704beb1e6f-original.jpg

    Some of these circuits are fairly complex:

    e97f171a-5e84-45b0-8c27-217620400c98-original.jpg

    Does anyone know what the substrate material is and what the function of these circuits are? They are typically located within ceramic enclosures.

    Next are small blocks of Si (again, located within ceramic enclosures) that have Au traces on them, and there seems to be a thin film between the traces and the Si. Not sure what these are for:

    4a7e4662-614a-4cb4-9344-c90f3c94ec57-original.jpg

    d09ecda5-2717-46f1-bb11-1de8fbb290e5-original.jpg

    The traces came off of these during the final Nitric Acid wash.

    Last are some more complex thin-film circuits, and again the substrate is not Si (maybe Ge?). These are incredibly fragile and little bits regularly break off whenever I try to handle them:

    b4e23cdb-f135-4de0-823a-da69a13bfb7c-original.jpg

    b8f18b76-3b5d-49b0-ab0f-c76d65632597-original.jpg

    Any info/guidance about these would be most appreciated! Thanks in advance....
     
  2. jcsd
  3. Mar 8, 2019 #2
    I have no idea what they are. Some look like RF.

    The top one is cool though, it almost looks like some kind of ASIC, love what I can only assume are data busses fanning out between who knows what they do blocks!
     
  4. Mar 8, 2019 #3

    Baluncore

    User Avatar
    Science Advisor

    It would help if you photographed the chip markings and terminals before disassembly, and provided a scale on the photos.
    You have asked too many unnumbered questions.

    The analysis of the substrate is difficult but you might be able to do a chemical spot test, or analyse / recognise the flame spectrum colour when it is burnt, maybe by an electric arc. You could measure a PN junction voltage, with a fragment in a curve tracer, like in a crystal set receiver.

    Picture 1. Looks a bit like a RISC processor core, but with few control circuits, so I guess is probably a direct digital synthesizer. Digital inputs on the left, phase accumulator in the middle, then IQ, sine and cosine DACs on the right.
    Picture 2. Could be huge arrays of small output transistors in parallel.
    Picture 3. Too many possibilities. Hard to identify the terminals and connection points.
    Pictures 4, 5. Maybe mosfet transistors.
    Picture 6. Clearly an RF front end. Probably an IQ mixer. Built from tuned transmission lines above a ground plane, with transistors and mixer diodes.
    Picture 7. The square spirals are inductors so it is an RF wireless interface. Maybe with arrays of RF transistors.
     
  5. Mar 9, 2019 #4

    Tom.G

    User Avatar
    Science Advisor

    PLEASE, number at least the photos.

    My guesses, for whatever they're worth.
    Picture 2: Possibly a T/R Switch
    Picture 3: A CPU
    Picture 6: Now that @Baluncore mentions it, yeah, it fits
    Picture 7: Agree again that the lower half is RF. The upper half could be Encoder/Decoder for the modulation. The two busses of 4 wires each at the top edge would be either Power/Ground, or RF output. (IIRC, Phones these days have multi-band capability.)
     
  6. Mar 9, 2019 #5

    davenn

    User Avatar
    Science Advisor
    Gold Member


    This, above all else, would have been great

    Many IC datasheets can be found by simple googling the part number :smile:


    D
     
  7. Mar 15, 2019 at 5:47 PM #6

    Andy Resnick

    User Avatar
    Science Advisor
    Education Advisor

    Don't know where else to post these images of the MEMS gyro:

    613dfca6-f243-4df4-8de9-087051045bb5-original.jpg

    5d10fb9d-6ca0-4cc7-8d93-e49bfe030a36-original.jpg
     
  8. Mar 17, 2019 at 12:24 AM #7

    davenn

    User Avatar
    Science Advisor
    Gold Member

    amazing technology :)
     
Share this great discussion with others via Reddit, Google+, Twitter, or Facebook

Have something to add?