Thank you very much for your valuable suggestion!
We will solve it as soon as possible!
BGA, stress on the PCB
I've a problem with a BGA. I've the impression that the balls broke then there is a too big mecanical stress on the PCB. I lost some dBm and when I press on the BGA I measure the good value! It's like the balls are take off the BGA or PCB and when you press on it the balls paste to the BGA or PCB.