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Can a resistor lose resistance after hot air?

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    Can a resistor lose resistance after hot air?

    I am curious if a 0402 resistor could go from 43 ohm to 0. In electronics class and my experience a resistor can degrade and gain resistance all the way up to not being able to conduct at all. I have never heard of a resistor decreasing in resistance and becoming 0 ohm or a dead short… that's not the direction they fail… or so I thought.

    I was attempting to remove a wson8 chip on an iMac motherboard and it required a lot of heat, on one side of the chip were 3 0402 resistors that were very close. I popped the chip out unintentionally out of the tweezers and sent those resistors flying. I was able to recover the 3 resistors and I measured the values: 15 ohm, 15 ohm, 0 ohm.

    Damn they were not all the same, I was able to acquire the schematics (yay) The problem is as I read the schematics I need a 15 ohm, 15 ohm and a 43 ohm 0402.

    This has been confusing for me because I didn't know that a resistor could become a 0 ohm resistor from applying too much hot air…. or did it, how could it?
    I proceeded to look for a spot that I could have maybe knocked a 4th 0 ohm resistor out of place and that perhaps I just didn't recover the 43 ohm but I do not see a forth place that is missing a resistor. I would just appear as that somehow this resistor became a 0 ohm resistor. I proceeded to closely look at the resistor to see if perhaps some little bit of solder or something was causing a direct short but I don't see any material causing a bypass of the resistor.

    I obviously don't want to put back a resistor measuring 0 ohms back when it should be 43 so I will have to order one… but I feel like perhaps I am missing something. I keep reviewing the schematic and attempting to follow traces but it is very difficult with the black coating covering the traces. I have a hard time believing a 3 resistors that got the same heat that only one would somehow lose resistance and I should keep reviewing things.

    #2
    Re: Can a resistor lose resistance after hot air?

    I am going to just order a 43 ohm resistor and place it, I don't understand why the one that came off the board measures 0. Albeit that I havn't been able to trace everything to the detail I would like, it gets pretty messy as especially as it goes to the chipset the three resistors are all in series to their respective pin of the chip and close so I am fairly confident where the resistors go and I cannot reuse the one measuring 0 as it needs to be 43.

    Still curious how it became a 0, looked closely for some solder on the side or anything causing this. I Didn't see anything.

    Even if I am wrong I'd rather error with more resistance, but i don't think I am.
    I am not looking forward to soldering these 0402 smd package components in, fingers crossed.

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