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I’m newish to electronics and I’m very curious, why is there a cross-hatch ground copper pattern opposite the touch pad on the AT42QT101X Capacitive Touch Breakout - I mean, why is any copper there at all?

I notice the adafruit version of this breakout also has the same ground copper cross-hatch pattern opposing the touch pad.

I’ve made my own version of this board for my project - and I didn’t include the cross-hatch ground copper under the touch electrode pad; because the only guidance (copied below) I could find in the AT42QT1010 spec sheet said to keep any ground copper away from the touch electrode

My board works mostly ok - but I’ve seen touch detection misses in the ballpark of 1 in 30 - which feels too high, so I’m wondering what I’m missing here?

“Ground planes around and under the electrode and its SNSK trace will cause high Cx loading and destroy gain. The possible signal-to-noise ratio benefits of ground area are more than negated by the decreased gain from the circuit so ground areas around electrodes are discouraged. Metal areas near the electrode will reduce the field strength and increase Cx loading and should be avoided, if possible. Keep ground away from the electrodes and traces.”

thanks, Kevin.