Leakage detection method using micromachined-thermal-convection accelerometer
AssigneeMemsic, Inc.
InventorsYaping Hua, Zongya Li, Hanwu Xiao
Life of this patent
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Abstract
A method and device for identifying leaks in or a leakage rate of an integrated circuit package. The method and device include integrating a micromachined-thermal-convection accelerometer in the integrated circuit package and evaluating the initial and subsequent sensitivities of the accelerometer. A change in sensitivity with time provides indicia of a leak and a measure of leakage rate.
Claims16
A method for detecting leaks in or a rate of leakage of a hermetically sealed integrated circuit package having a cavity, the method comprising:
- integrating a micromachined-thermal-convection accelerometer in the hermetically sealed package;
- measuring an initial inner pressure (P1) of the cavity;
- measuring an initial sensitivity (S1) of the micromachined-thermal-convection accelerometer in the cavity;
- measuring a second sensitivity (S2) of the micromachined-thermal-convection accelerometer in the cavity at some time (t);
- calculating a second inner pressure (P2) of the cavity at time (t);
- and
- calculating an average leakage rate (R) using the initial inner pressure (P1), the second inner pressure (P2), and time (t), wherein the average leakage rate (R) is calculated using the equation:
- R=(P2−P1)/t.
A method for detecting leaks in or a rate of leakage of a hermetically sealed integrated circuit package having a cavity, the method comprising:
- integrating a micromachined-thermal-convection accelerometer in the hermetically sealed package;
- comparing a first sensitivity (S1) of the accelerometer with a second sensitivity (S2) of said accelerometer and calculating a ratio of sensitivity (S2/S1) therefrom;
- and
- calculating the rate of leakage using an initial inner pressure (P1), a second inner pressure (P2) that is a function of the ratio of sensitivity (S2/S1), and time (t) between the initial and second inner pressures.
A method for detecting leaks in or a rate of leakage of a hermetically sealed integrated circuit package having a cavity, the method comprising:
- integrating a micromachined-thermal-convection accelerometer in the hermetically sealed package;
- measuring an initial inner pressure (P1) of the cavity;
- measuring an initial sensitivity (S1) of the micromachined-thermal-convection accelerometer in the cavity;
- measuring a second sensitivity (S2) of the micromachined-thermal-convection accelerometer in the cavity at some time (t);
- calculating a second inner pressure (P2) of the cavity at time (t) using the equation:
- P2=P1*(S2/S1)1/2;
- and
- calculating an average leakage rate (R) using the initial inner pressure (P1), the second inner pressure (P2), and time (t).
Dependencies are inferred from the claim text.