32kHz crystal and ultrasonic welding

[Alberto Perosa]

Ultrasonic welding is commonly used to seal plastic enclosures for electronic devices.
32kHz crystals can be damaged by this type of welding and manufacturers recommend not to use ultrasonic welding.
Since we use a 32kHz crystal for precise timing on nRF52, I ask if anyone has experience with crystal failures caused by ultrasonic frequencies or tested practical solutions to this issue.

[Hung Bui]

Hi Alberto, 

I agree with Nguyen on that you should look for the option with Mems oscillator. Our nRF52 does support BYPASS mode to use with rail-to-rail external source.

Another option is to find anti-ultrasonic crystal but I don't think it's very popular.