To design PCB with 0.8mm pitch BGAs, is ENIG PCB is better than Tlectro-plating PCB? Why? Than, what is the most effective way to determine the connection between BGA and PCB is good and strong enough?
Use ENIG, plated finish will be too thick and make for a brittle joint. ENIG is self limiting so this condition cannot be present.
To ensure that the bond is strong for BGA you must ensure that process is under control. The correct reflow profile will ensure the joints are good. You may want to Xray these joints however for shorting or excessive voiding.