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The Tragedy of Chestnut and the Qian Li 3D stencil

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  • The Tragedy of Chestnut and the Qian Li 3D stencil

    This was my first attempt to reball a small IC with Qian Li 3D. (I have previously used QianLi for larger ICs no problems!) I tried this with 2 different Qian Li 3D stencils - destroying two Chestnuts - same result.
    I struggled repeatedly to get Chestnut to align in the 3D holder. But Chestnut would neither sit flat, nor align. - With repeated attempts the placeholder eventually took a chunk out of Chestnut..
    Chestnut would not sit flat in the 3D placeholder and solder collected under the stencil between the balls.
    I cried and tried again. This time no solder under the stencil but the balls were grossly uneven . But Chestnut was already dead by 3D mutilation anyway. RIP Little Chestnut!

    My third Chestnut. Using a cheap solder stencil securing another Chestnut on the back with Kapton tape. Chestnut easily aligned and secured. Same solder paste, same hot air and time. Result perfect reball. I repeated with another Chestnut. Same result - perfect reball. Success!

    I 'm pretty convinced that Qian Li in this instance was the problem. I'm not exactly sure why - maybe it’s the way the 3D is moulded and completely surrounds the IC. And others may claim not to have had this problem? I am interested to know what your experience is of reballing smaller ICs like Chestnut with Qian Li 3D stencils.
    Attached Files