Method for testing the leakage rate of vacuum encapsulated devices
AssigneeFraunhofer-Gesellschaft zur Foederung der angewandten Forschung e.V.
InventorsWolfgang Reinert, Dirk Kaehler, Peter Merz
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Abstract
The present invention is directed to a method for testing the leakage rate of an encapsulated device comprising the step: bombing the device with a neon and/or argon atmosphere using a bombing pressure of at least more than environmental pressure and measuring the quality factor before and after bombing. Preferably, the bombing time is about 10 to 100 hours, and the bombing pressure is 1.5 to 100 bar, more preferably 1.5 to 5 bar and most preferably about 4 bar. With this test, the leakage rate of fine leaks of the device may be determined.
Claims20
A method for testing the leakage rate of an encapsulated device having a device cavity of below 5 mm3 and including a microresonating structure, comprising the steps of:
- (a) bombing the device with a neon or argon atmosphere using a bombing pressure of at least more than environmental pressure;
- (b) measuring the quality factor of the microresonating structure before and after bombing, wherein the measurement of the quality factor is performed by measuring the damping properties of the resonating structure within the encapsulated device (“ring-down method”);
- and
- (c) calculating a cavity pressure before and after bombing from the measurement according to (b), wherein a decrease in the quality factor indicates a leakage.
A method for identifying a leaking encapsulated device including a microresonating structure comprising the steps of:
- (a) bombing the device with a neon or argon atmosphere using a bombing pressure of at least more than environmental pressure;
- (b) measuring the quality factor before and after bombing, wherein measurement of the quality factor is performed by measuring the damping properties of the resonating structure within the encapsulated device (“ring-down method”);
- (c) calculating a cavity pressure before and after bombing from the measurement according to (b), and determining whether said device leaks by comparing the cavity pressure before and after bombing.
A method of identifying encapsulated devices including microresonating structures that are not sufficiently tight to provide an expectation of a service life time of 5 to 15 years comprising the steps of:
- (a) bombing the devices with a neon or argon atmosphere using a bombing pressure of at least more than environmental pressure and a bombing duration of about 24 hours;
- (b) measuring the quality factor before and after bombing, wherein measurement of the quality factor is performed by measuring the damping properties of the resonating structure within the encapsulated device (“ring-down method”);
- (c) calculating a cavity pressure before and after bombing from the measurement according to (b), and determining whether said devices are sufficiently tight by comparing the cavity pressure before and after bombing, wherein an increase in the cavity pressure of more than 1% after said bombing indicates that said encapsulated devices are not sufficiently tight to provide a service life time of 5 to 15 years.
A method of detecting damage to devices that have encapsulated microresonating structures, the method comprising the steps of:
- (a) bombing the devices with a neon or argon atmosphere using a bombing pressure of at least more than environmental pressure;
- (b) measuring the quality factor before and after bombing, wherein measurement of the quality factor is performed by measuring the damping properties of the resonating structure within the encapsulated device (“ring-down method”);
- (c) calculating a cavity pressure before and after bombing from the measurement according to (b), and determining whether said devices are damaged by comparing the cavity pressure before and after bombing.
Dependencies are inferred from the claim text.