If you have a related question, please click the "Ask a related question" button in the top right corner. The newly created question will be automatically linked to this question.
Provide as much spacing as possible between buttons
Provide significant spacing between buttons and nearby ground planes
Route all electrode connection traces on the PCB layer furthest from the surface
Set sensor idle states to High-Z (floating) so that nearby sensors don’t provide coupling points that can cause false detections
If possible, use a non-conductive enclosure for the product
Spill Rejection Applications
Spill rejection applications include those which are able to detect when a fluid spill has occurred on the sensing panel. Common applications are white goods such as a cooking surface control panel. The goal of spill rejection is not to enable full touch detection (which is extremely difficult when moisture or fluids cover multiple keys and/or ground), but simply to detect the presence of a spill and lock out the keypad until the spill is cleared by a user. This is most commonly achieved with the use of a guard channel, whose purpose is to detect large objects as well as spills.
Design Tips for Spill Detection
When designing a spill detection application:
Implement a guard channel to detect when a large unknown object or some kind of spill comes into contact with the sensing panel
In software, utilize the guard channel to mask reporting of touches on other keys when a spill is detected.
The CAPTIVATE-PHONE demonstration panel has a guard channel that is used for proximity sensing, palm rejection, and basic moisture rejection.
