I've got a technician training on BGA Reballing and we are making progress.

However now for some reason he's killing the motherboards entirely that he's working on. Thank goodness we are well stocked on testing laptops - but we cant quite figure out what hes doing wrong.

Previously we had popcorning issues but resolved this through some heat adjustments and techniques - however now for some reason the boards being killed all together.

I suspect our heat adjustments may be driving thermal distortion in the motherboard but wanted to get some opinions from people who have tried it already.