Patent ID: 8638178

Claim:
A method of testing a packaged thin-film piezoelectric-on-semiconductor microelectromechanical resonator, comprising: measuring a quality factor of resonance (Q) of the packaged resonator at at least two unequal temperatures to determine a change in quality factor (EQ) over a temperature range (ΔT) spanning a smallest and largest of the at least two temperatures, for a packaged resonator having a Q AIR <Q TED , where Q AIR is the quality factor of resonance of the packaged resonator due to air damping and Q TED is the quality factor of resonance of the packaged resonator due to thermoelastic damping, said measuring comprising determining that the packaged resonator has a defective hermetic seal in the event a ΔQ/ΔT of the packaged resonator is at least 50% different than an otherwise equivalent packaged resonator having a hermetic seal.