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Need to build some type of mold housing for a NAND Flash Chip or a Micro Controller Unit Located on USB Flash Drives
Last Post 08 Feb 2013 05:06 AM by Engineer-3. 6 Replies.
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Engineer-3
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Posts:4

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11 Jan 2013 06:03 AM
    Hello,

    First of all, I am not an actual engineer. We have some concept ideas and will utilize the employment of an actual engineer once we have more information behind this all. With this said, please forgive my not so technical way of thinking and explaining all of this.

    We are attempting to build some type of an enclosure or housing that would allow us to perform chip swaps from 2 duplicate devices.

    1. We have 2 identical duplicate USB Flash Drives (Full PCB with components inside of casing).

    2. Device #1 is not working due to a failed MCU (Micro Controller Unit).

    3. Device #2 is in a working condition.

    4. We would like to swap the bad micro controller from device #1 with the good micro controller from device #2.

    5. One problem, the micro controller is surface mounted; meaning, all of the soldering points are under the chip. It is hard to properly align all of the connecting points (most of the time there are over 20) with the PCB soldering points due to a visibility issue (we cannot see under the MCU as it is being connected to the surface of the PCB).

    6. At this point, we have 2 different options.
    a) Purchase expensive imaging equipment that will allow us to see through the PCB and chip to allow for proper alignment. Not sure if there is equipment like that out there? I am envisioning something along the lines of a X-Ray machine?? Maybe some type of imagining equipment that would allow us to accomplish this is not too expensive?? Please give any suggestions as to what the name of the equipment could be (brand name, links etc...).
    b) Create some type of housing or mold that would temporarily attach to the PCB securely. Basically, a mold that would be the perfect size to allow us to just place the chip inside of this mold and then heat the whole board with the MCU Chip inside of housing. After heating, the good Micro Controller chip would be properly attached to the PCB and this temporary mold (housing) could be removed.

    7. And whalaa, we have a working USB drive again as the bad MCU was replaced with a working one.

    8. Attached is an image of a USB device with a surface mounted controller.

    Again, please excuse my not-so technical verbiage in this write up.

    Any and all comments, suggestions and questions are appreciated.

    Thanks ahead,

    Engineer-3
    Niel
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    Posts:193

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    11 Jan 2013 02:16 PM
    Engineer-3:

    What is your purpose for doing this?

    Is it to save / recover the data or is it to actually recover the rest of the electronics?

    If the former there may be more reliable less expensive ways to accomplish this.

    If it is the latter -
    -What percentage of systems fail due to an MCU failure?
    -Is this for a specific Flash Drive construction or will it be universal?


    Niel Leon
    Engineering.com
    Engineer-3
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    Posts:4

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    05 Feb 2013 10:09 AM
    Hello Niel,

    Thanks for the response and my apologies for not getting back to you sooner in regards to this. I was expecting that engineering.com would send me an alert in regards to any replies (never received one).

    Anyhow, yes this would be predominantly used to perform a data recovery on a particular device. It would be specific to each type of a different flash drive, so not universal. We would need to create multiples of these types of enclosures to cater to different device types of physical layouts.

    Thanks,

    Engineer...
    Niel
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    Posts:193

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    05 Feb 2013 03:19 PM
    OK:

    That makes sense. Recovering valuable data, may make this a cost effective process. Data recovery is your primary objective. You are not trying to put these units out into the world.

    As a result this is really a specialized de-soldering tool that would hook up to a heating unit.

    Do you have the have the technical data on the MCU's in question?

    Do you have any samples to work from to confirm the process once the basic design is built for initial testing?

    What sort of de-soldering stations do you have available to you?

    Niel

    PS: to get notifications you need to request them. See the radio box below the submit button - Subscribe.
    Engineer-3
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    Posts:4

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    06 Feb 2013 07:25 AM
    Not sure if you follow 100%.

    1. We have de-soldering capabilities for taking chips off, this is not the problem.

    2. The problem is that we do not have a proper way of re-soldering a duplicate good chip back onto the bad device as all of the pins are located on the bottom area of the chip. We cannot physically see that all of the connectors have been perfectly lined up to attempt re-soldering. So, if we build some type of an enclosure that will perfectly sit around the affected are then we could just drop the chip inside of this enclosure knowing that the chip is properly aligned with the PCB and commence with the re-soldering

    3. We only have the data that is located on the actual MCU's themselves, we do not have pin-outs. In this case pin-outs and data sheets would not be necessary because we are tlaking about virtually 100% identical device that have the exact PCB layout and the Chips are 100% the same. We know that this method of recovery works 100%, but this has only been experimented with when the actual MCU chips have connecting legs on the sides of the chips where we have no issue of re-soldering the chips onto another a PCB because the connectors are visible as we are doing it.

    Examples of MCU's:

    A. Easy to Solder because connectors are located on the side of the chip: http://www.copy-mcu.com/wp-content/uploads/2011/09/atmel.jpg

    B. Hard to Solder because the connectors are located on bottom of chip: http://johndayautomotivelectronics.com/wp-content/uploads/2012/11/Freescale-11-13-12AUT-P27794_MPC5777M_ChpSht-HR-2.jpg

    4. We have a ton of in-house devices that can be utilized for testing.

    5. We have regular heating guns for de-soldering chips. Link to example: http://compare.ebay.com/like/350493137410?var=lv<yp=AllFixedPriceItemTypes&var=sbar

    Thanks,

    Engineer
    Niel
    Basic Member
    Basic Member
    Posts:193

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    07 Feb 2013 02:06 PM
    I think understand. You need a mask or alignment fixture which will allow you to properly align the new chip over the exact location from which the old MCU was removed.

    That should be relatively straight forward.

    Do the circuit boards have alignment or registration marks which can be used to properly align them with in a system?

    If this is the case then it should be possible to develop a system with two xy stages one over the other which would allow you to align the soldering head and the new MCU chip to the to the proper location on the board.

    There may need to be multiple masks which are designed to hold specific circuit board and MCU chips. These would be relatively to create as needed.

    Niel
    Engineer-3
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    08 Feb 2013 05:06 AM
    Hi Niel,

    Yes, that is exactly it. The problem is that I am not sure where to even begin with any of this? How do we get this accomplished?

    Any ideas would be helpful.

    Thanks ahead,
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