Trouble reballing a Tri-Star chip

I'm practicing tri-star replacement on an old 6. I've learned that a properly balled logic board AND chip are essential to end up with the "muffins" you find under other BGA type chips. When everything is done right, there are no solder bridges between the pads, you can "jiggle" the chip when it's at temp and surface tension snaps the chip into place. If I drop a new chip (pre-balled with lead-free) I'm able to jiggle, but I don't see any "muffins" around the edge. I'm thinking I don't have enough solder on the logic board, the pre-balls are two small, or both. So I wick everything clean, drag solder new humps onto the logic board, and then try to put humps on the tri-star chip. But no matter what I try, cannot put new humps or solder balls on the tri-star chip. I've tried drag soldering, and paste with a stencil and hot air. I've tried low-temps and high temps. I'm only using leaded solder (63/37). I've tried 3 different fluxes. For some reason, once I take off the factory solder from a tri-star chip, I CANNOT get the chip to accept new solder. No mater how much cleaning I've done, or which flux/heat I've used.

I'm guessing there's some chemistry or bonding thing going on here that I have not learned. Has anyone else seen this? How do you solve it? How do you get the tri-star chip to accept new solder after cleaning up the old?

Thanks to anyone that is willing to share a thought or have a suggestion!

Ответ на этот вопрос У меня та же проблема

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