CapSense® with a Flex PCB - KBA82731

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Question: What are the design guidelines for using Flex PCB instead of FR4 PCB for CapSense designs?

 

Answer:

You need to follow two important guidelines when using a Flex PCB for your CapSense design:

  1.   You may need to use a slower CapSense clock, because the resistance per square inch for Flex is higher.
  2.   Do not use a hatched ground below your sensor. Flex PCB is much thinner than FR4 PCB, and a hatched ground will increase parasitic capacitance.

Refer to the design guide Getting Started with CapSense for more design guidelines.