BGA ball and land design problem

2/1/2017 6:26:27 PM

Hello, recently we changed supplier of the LF BGA, we did corossection and now have doubts... previous BGA specs : pitch 1mm, ball diameter 0.6mm future BGA specs : pitch 1mm, ball diameter 0.4mm

on the crossecrion we found that one of the ball seems cracking from the package - under x-ray we saw void in other ball but this one seem quite normal, checking more BGA under x-rays show more voiding that on the opponent (previous) parts

land pad on the PCB is 0.45, profile is our standard LF and works for most of the products without any changes (12 zones myReflow) supplier of the BGA say that land pad is too big and is generating voiding problems

we will apprieciate any comments on that, as we are beginning with BGA so there is still a lot to learn - IPC 7095 is coming in the next few days.