You need to select the false touch board, and tuner it.
Does these boards have a high noise?
Does these boards have a poor consistency?
Can you tell me how you set the finger threshold, noise threshold and hysteresis?
At the same time, you need to clarify what device you do, and what the working environment?
thanks for the reply
1. power supply no noise as it is connected to USB port
2. I am using auto tune mode so i have not tune it manually
3. device is CY8C4245AXI-483
4. this problem i am facing in 1 or 2 board out of 100 boards.
5. working environment is normal. even on lab table with temp 25 degree
Sometimes due to manufacturing tolerance, board to board variation can happen in terms of thickness and material use.
I recommend to check the Cp of the CapSense on those boards. The Cp would certainly be different from the passed boards and that is the reason it would have failed.
2nd there could be Pin shorts to GND or Open which can lead to this issue.