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Reballing Temps don't seem right

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    Reballing Temps don't seem right

    Hello,

    Thank you for reading my post. This is my first post on this website. I have looked for hours and i am either not putting in the right words, or it's not been asked specifically the way im looking to have it answered.

    The question is this, i am working on practicing reballing on xbox 360's gpu's and cpu's.

    The problem I am having is this:
    I know that lead free solder goes into a liquid state at the temp 213c. However, i have tried to do this many many times using my hot air rework station and a 4141 nozzle which fits the gpu perfectly and it has a triple net in the middle to even out air. I have used this one thermal coupler and shows the reading at 220 when i hit 230 on station, however no matter how i do it and the thermal coupler says it's over leadfree melting point, they are not melted at all, infact they are very solid still, for me to lift a chip it has to hit 270c on my tc, and my rework station has to be at 300c or so. I am using Kingbo flux.

    I ordered a new thermal coupler (a nicer more expensive one) however, i find it odd that the termal coupler i have now seems to follow the reading of the hot air rework station perfectly when i just use it to check the air temp. This can't be coincidence.
    The thermal coupler and rework station are from different manufactures, yet they seem to follow eachother with a 5 degree fluctuation.

    This issue is driving me crazy, i find that i don't have any popcorning(like im supposed to at those temps accouring to people online), and i test the gpu using the test point referencing a gpu i bought online from a manufacture the numbers are all right and the gpu doesn't appear to be broken.

    I just don't understand it, are my tools lying to me? from what ive read anything past 250 will completely fry the gpu, the earliest point i can lift the gpu is when my tc reads 270c.



    How can it be like this? How can i be able to lift at 270c rework station at 300c for leadfree? i have watched every youtube video i can find on the subject, and i notice this as well the flux doesn't start to let off (steam?) till i hit 250c on coupler however other people seem to be getting this (steam?) at lower temps using the same flux?

    Interestingly though on a different note, i can flow leaded solder at 200c thermal coupler reading and 210c rework using kingbo on an xbox.

    Lead is within it's range, lead free isn't, same flux.

    Sorry if my english is a little sloppy, not my first language.

    #2
    Re: Reballing Temps don't seem right

    Where are you putting the thermocouple, and do you have a bottom heater?
    Originally posted by PeteS in CA
    Remember that by the time consequences of a short-sighted decision are experienced, the idiot who made the bad decision may have already been promoted or moved on to a better job at another company.
    A working TV? How boring!

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      #3
      Re: Reballing Temps don't seem right

      Yes I am using a bottom heater, when the top of the board reaches 150c I wait 5 min, then start my top heating process.

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