I am designing a board and the problem I am facing on the board hardware is that the core power supply and ground has very low impedance of around 0.3 Ohm. This is leading to a conclusion of two nets as if these are shorted together. Although the current drawn for that particular assembly for core power supply is 9A the impedance would be low(may be around 4-5 Ohm).But is 0.2 Ohm a correct value. We have done the x-ray analysis of BGA, and no solder bridging is observed. Can anyone suggest what could be the issue?