Packaging a sealed cavity in an electronic device
An electronic device includes a package substrate, a circuit assembly, and a housing. The circuit assembly is mounted on the package substrate. The circuit assembly includes a first sealed cavity formed in a device substrate. The housing is mounted on the package substrate to form a second sealed cavity about the circuit assembly.
1. An electronic device, comprising:
a package substrate;
a circuit assembly mounted on the package substrate, the circuit assembly including a first cavity formed in a device substrate;
a sealing plate attached to the device substrate, enclosing the first cavity and configured to maintain a first pressure within the first cavity; and
a housing attached to the package substrate forming a second cavity about the circuit assembly, and configured to maintain a second pressure within the second cavity.
2. The electronic device of claim 1 , wherein the first cavity includes a channel formed in the device substrate.
3. The electronic device of claim 1 , further comprising a pressure sensor coupled to the sealing plate and configured to measure pressure within the first cavity as a function of displacement of the sealing plate.
4. The electronic device of claim 1 , wherein the sealing plate includes a dielectric membrane.
5. The electronic device of claim 1 , including:
an acoustic sensor coupled to the sealing plate and configured to measure vibration of the sealing plate; and
control circuitry coupled to the acoustic sensor, the control circuitry configured to determine pressure within the first cavity as a function of the mechanical harmonic signature of the sealing plate.
6. The electronic device of claim 1 , including a pressure sensor coupled to the housing and configured to measure pressure within the second cavity as a function of displacement of the housing.
7. The electronic device of claim 1 , including:
an acoustic sensor coupled to the housing and configured to measure vibration of the housing; and
control circuitry coupled to the acoustic sensor, the control circuitry configured to determine pressure within the second cavity as a function of the mechanical harmonic signature of the housing.
8. The electronic device of claim 1 , wherein the first cavity is a waveguide of a millimeter-wave chip scale atomic clock.