I want to make my first PCB with a BGA microcontroller, an NXP RT1062 and I have some doubts.
1.- Will 4 layers on the PCB suffice?
2.- Is it possible to put the decoupling capacitors on the same side of the PCB as the microcontroller? Having to solder on both sides, using an oven, would be a problem, I don't know how I could do it.
A well-planned 4 layer design may suffice but as somebody has already said, it depends on the rest of your design. Layers can dissipate heat effectively. So, check the thermal requirement of your microcontroller and other components.