BGA Repair Problems

2/28/2017 1:42:29 PM

Have an SRT w/preheat, 18 layer board all copper, 456 BGA needs to be removed and replaced. The manufacturer is Chip Express and during reflow it warps up or down. Causing either opens or shorts on the corners. I was using gel flux with multiple profiles. Now going to try dispensing paste with Camelot using a profile on the lower end of the window. It should reduce the peak temperature and time in reflow, hopefully will not warp. We have baked the parts prior to trying to reflow them. Could use help with this problem part, "Chip Express" Thanks in advance