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Thread: Ever heard of multilayer PCBs developing S/C between layers?

  1. #1
    HandyMan Newbie
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    Sep 2004
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    UK
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    Default Ever heard of multilayer PCBs developing S/C between layers?

    Hi,

    I ask this because someone I know has been told that their laptop needs a new motherboard.

    The ' laptop specialists' in question claim that they replaced an SMD fuse on the motherboard but could not find the cause of the S/C present. They say they 'lifted' every component (on the board? in the power input area? - either way, that's some feat!) but to no avail, it didn't remove the S/C.

    So, there conclusion is that there is: "... a fault in the multilayering of the
    motherboard ... as can't "break apart" the layers it couldn't be fixed..."

    Now, he doesn't know if they mean that actual layers are shorting somehow, or if tracks on one of the inner layers are shorting together.

    Has anyone heard of either occurrence in an otherwise previously working device? I've repaired things which have been factory rejects after finding thin, close-together tracks not etched properly, and so shorting together, but never previously working things except for HT sections on TV sets where a slightly conductive liquid has dried on the board and eventually caused a conductive trace to arc its way across - and deeply into - the board.

    He's not so keen to replace the motherboard like that, and I'm not so keen to believe that the S/C is due to multilayer problems. Thin tracks on an inner layer going O/C due to excessive current or whatever, that I could imagine, but S/C?

    Maybe I've just never heard of it before...?

    Thanks
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  2. #2
    tansis Newbie
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    Default

    Considering that the motherboard was built by a machine , lifting and replacing SMD components by hand whilst it can be done , it is not undertaken lightly. [ wether they actually replaced the lifted components is another argument alltogether ]

    I doubt it's a problem in the pcb, more likely an IC failure.

    My old Dell laptop bit the dust after the failure of the £5 cooling fan, cost of a replacement motherboard was twice what I paid for the machine. When asked about repairing the existing MB they replied that is was not economical to even attempt such a feat.
    It may seem like a good idea at the time but.. never stir your cold coffee with a soldering iron.

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