A method for predicting the failure time of airtightness of micro-nano sensor packaging

Abstract

The present invention discloses a method for predicting the airtight failure time of a micro-nano sensor package. The method comprises the following steps: determining the leakage rate of the micro-nano sensor at different times and establishing a functional relationship between the leakage rate and time; then establishing a prediction model based on the functional relationship and the internal volume of a packaging cavity of the micro-nano sensor, and determining the changing relationship between the pressure in the packaging cavity and time according to the prediction model; then predicting the airtight failure time of the package based on the changing relationship and the failure threshold of the packaging cavity pressure, thereby realizing the prediction of the airtight failure time of the micro-nano sensor and the reliability prediction of the airtight packaging of the micro-nano sensor, which only requires a small amount of data acquisition, and effectively reduces the time required for the prediction.

Description

Technical Field

[0001] The invention belongs to the technical field of micro-nano sensors, and in particular relates to a method for predicting the airtight failure time of a micro-nano sensor package. Background Art

[0002] The internal structure of micro-nano sensors is generally at the micron or even nanometer level. Its design and manufacturing involve multiple disciplines and engineering technologies, such as physics, semiconductors, optics, electrical engineering, chemistry, materials engineering, mechanical engineering, medicine, information engineering and bioengineering.

[0003] Packaging is the main factor affecting the total production cost of micro-nano sensors. Commonly used industrial wafer-level vacuum packaging processes include anodic bonding, silicon-silicon bonding, and eutectic solder bonding. For ordinary plastic-sealed pressure sensors, packaging accounts for 20% of the total production cost, while for pressure sensors that work continuously in harsh environments (high pressure and rapid temperature changes), packaging accounts for 95% of the total production cost. Other micro-nano sensors have similar packaging costs.

[0004] The complex geometry, high diversity and tiny size of micro-nano sensors are the reasons for their high packaging costs. Therefore, it is necessary to study the airtightness of their packaging and predict airtightness failure. However, the size of the micro-nano sensor packaging cavity is very small, and undetectable leakage will cause packaging failure.

[0005] Therefore, how to predict the failure time of the airtightness of the micro-nano sensor package is a technical problem to be solved by those skilled in the art. Summary of the invention

[0006] The purpose of the present invention is to predict the failure time of airtightness of micro-nano sensor packaging, and a method for predicting the failure time of airtightness of micro-nano sensor packaging is proposed.

[0007] The technical solution of the present invention is: a method for predicting the airtight failure time of a micro-nano sensor package, comprising the following steps:

[0008] S1. determining the leakage rate of the micro-nano sensor at different times, and establishing a functional relationship between the leakage rate and time;

[0009] S2, establishing a prediction model based on the functional relationship and the internal volume of the packaging cavity of the micro-nano sensor, and determining the relationship between the pressure in the packaging cavity and time according to the prediction model;

[0010] S3. Predicting the failure time of the packaging airtightness based on the change relationship and the failure threshold of the pressure in the packaging cavity.

[0011] Furthermore, the functional relationship between the leakage rate and time is specifically shown in the following formula:

[0012]

[0013] Wherein, L(t) is the functional relationship between the leak rate and time, L0 is the initial value of the leak rate, t0 is 1 hour, and t is time.

[0014] Furthermore, the prediction model is specifically shown in the following formula:

[0015]

[0016] Wherein, P(t) is the pressure in the packaging cavity at time t, L(t) is the functional relationship between the leakage rate and time, and V is the internal volume of the packaging cavity.

[0017] Furthermore, the relationship between the pressure in the packaging cavity and time is specifically shown in the following formula:

[0018]

[0019] Wherein, P(t) is the pressure in the packaging cavity at time t, L(t) is the functional relationship between the leakage rate and time, V is the internal volume of the packaging cavity, t0 is 1 hour, and t is time.

[0020] Furthermore, the step S3 specifically includes the following sub-steps:

[0021] S31, determining a failure threshold of the pressure in the packaging cavity;

[0022] S32. Determine the failure time based on the prediction model and the failure threshold.

[0023] Compared with the prior art, the present invention has the following beneficial effects:

[0024] The present invention determines the leakage rate of the micro-nano sensor at different times and establishes a functional relationship between the leakage rate and time; then, based on the functional relationship and the internal volume of the packaging cavity of the micro-nano sensor, a prediction model is established, and the changing relationship between the pressure in the packaging cavity and time is determined according to the prediction model; then, based on the changing relationship and the failure threshold of the packaging cavity pressure, the packaging airtightness failure time is predicted, thereby realizing the prediction of the airtightness failure time of the micro-nano sensor. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] Figure 1 FIG. 1 is a flow chart of a method for predicting the airtight failure time of a micro-nano sensor package provided by an embodiment of the present invention;

[0026] Figure 2 Shown is a schematic diagram of the comparison between the prediction curve of the prediction model and the experimental data. DETAILED DESCRIPTION

[0027] The following will be combined with the drawings in the embodiments of the present application to clearly and completely describe the technical solutions in the embodiments of the present application. Obviously, the described embodiments are only part of the embodiments of the present application, not all of the embodiments. Based on the embodiments in the present application, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of this application.

[0028] This application proposes a method for predicting the airtight failure time of micro-nano sensor packaging, such as Figure 1 The figure is a flow chart of a method for predicting the airtight failure time of a micro-nano sensor package proposed in an embodiment of the present application. The method comprises the following steps:

[0029] Step S1, determining the leakage rate of the micro-nano sensor at different times, and establishing a functional relationship between the leakage rate and time.

[0030] In the embodiment of the present application, the leakage rate of the micro-nano sensor at different times can be obtained by a specified instrument, and the leakage rate at different times is shown in the following Table 1:

[0031] Table 1

[0032]

[0033] In the embodiment of the present application, the functional relationship between the leakage rate and time is specifically shown in the following formula:

[0034]

[0035] Wherein, L(t) is the functional relationship between the leak rate and time, L0 is the initial value of the leak rate, t0 is 1 hour, and t is time.

[0036] Step S2: establishing a prediction model based on the functional relationship and the internal volume of the packaging cavity of the micro-nano sensor, and determining the relationship between the pressure in the packaging cavity and time according to the prediction model.

[0037] In the embodiment of the present application, the prediction model is specifically shown as follows:

[0038]

[0039] Wherein, P(t) is the pressure in the packaging cavity at time t, L(t) is the functional relationship between the leakage rate and time, and V is the internal volume of the packaging cavity.

[0040] Specifically, for molecular flow, the relationship between conductance and leakage rate is:

[0041] L=CP air ;

[0042] Where L is the leakage rate, C is the conductance, and P air is standard atmospheric pressure.

[0043] According to the gas flow equation, the pressure difference in the packaging cavity is:

[0044]

[0045] Where V is the internal volume of the packaging cavity, Q is the gas leakage per unit time, C is the flow conductance, and P out is the external pressure of the package cavity, P is the internal pressure of the package cavity, dP(t) is the differential of pressure, and dt is the differential of time

[0046] Due to the pressure difference between the inside and outside of the packaging cavity, the external gas will enter the interior through the leak hole, and the internal pressure changes to:

[0047]

[0048] Where P(t) is the pressure in the package cavity at time t, C is the flow conductance, and P air is the standard atmospheric pressure, P0 is the initial pressure inside the cavity, exp is an exponential function with e as the base, V is the internal volume of the packaging cavity, and L(t) is the functional relationship between the leakage rate and time.

[0049] The curve of internal pressure changing with time is close to a straight line in the first section, and the slope gradually decreases in the second section. For the reliability analysis of micro-nano airtight packaging, failure occurs in the first section, so the model can be simplified. Combining the above, the prediction model can be obtained:

[0050]

[0051] Wherein, P(t) is the pressure in the packaging cavity at time t, L(t) is the functional relationship between the leakage rate and time, and V is the internal volume of the packaging cavity. The simplified model reduces complexity while ensuring accuracy.

[0052] In the embodiment of the present application, the relationship between the pressure in the packaging cavity and time is specifically shown in the following formula:

[0053]

[0054] Wherein, P(t) is the pressure in the packaging cavity at time t, L(t) is the functional relationship between the leakage rate and time, V is the internal volume of the packaging cavity, t0 is 1 hour, and t is time.

[0055] The model is verified by experimental data of the change of air pressure inside the micro-nano sensor packaging cavity with time. The data comes from a MEMS device that uses the surface activated bonding (SAB) method to bond Si / Si at room temperature, such as Figure 2 Comparing the prediction curve of the prediction model with the experimental data, it can be seen that the model's prediction of the internal pressure of the packaging cavity is relatively close to the experimental data.

[0056] Step S3: predicting the failure time of the packaging airtightness based on the change relationship and the failure threshold of the pressure in the packaging cavity.

[0057] In the embodiment of the present application, step S3 specifically includes the following sub-steps:

[0058] S31, determining a failure threshold of the packaging cavity pressure;

[0059] S32. Determine the failure time based on the prediction model and the failure threshold.

[0060] Specifically, according to the specific working conditions, the failure threshold of the pressure in the micro-nano sensor packaging cavity is determined. -15 Pa m 3 / s, the package cavity volume is 6.72mm 3 When the failure threshold is 500Pa, the failure time of the micro-nano sensor airtight packaging due to leakage is about 35.5 years.

[0061] Those skilled in the art will appreciate that the embodiments described herein are intended to help readers understand the principles of the present invention, and should be understood that the protection scope of the present invention is not limited to such specific statements and embodiments. Those skilled in the art can make various other specific variations and combinations that do not deviate from the essence of the present invention based on the technical revelations disclosed by the present invention, and these variations and combinations are still within the protection scope of the present invention.

Claims

1. A method for predicting the airtight failure time of a micro-nano sensor package, characterized in that: The following steps are involved: S1. determining the leakage rate of the micro-nano sensor at different times, and establishing a functional relationship between the leakage rate and time; The functional relationship between the leak rate and time is specifically shown in the following formula: Wherein, L(t) is the functional relationship between the leak rate and time, L0 is the initial value of the leak rate, t0 is 1 hour, and t is time; S2, establishing a prediction model based on the functional relationship and the internal volume of the packaging cavity of the micro-nano sensor, and determining the relationship between the pressure in the packaging cavity and time according to the prediction model; The prediction model is specifically shown in the following formula: Wherein, P(t) is the pressure in the packaging cavity at time t, L(t) is the functional relationship between the leakage rate and time, and V is the internal volume of the packaging cavity; S3. Predicting the failure time of the packaging airtightness based on the change relationship and the failure threshold of the pressure in the packaging cavity.

2. The method for predicting the airtight failure time of micro-nano sensor packaging according to claim 1, characterized in that: The relationship between the pressure in the packaging cavity and time is specifically shown in the following formula: Wherein, P(t) is the pressure in the packaging cavity at time t, L(t) is the functional relationship between the leakage rate and time, V is the internal volume of the packaging cavity, t0 is 1 hour, and t is time.

3. The method for predicting the airtight failure time of micro-nano sensor packaging according to claim 1, characterized in that: The step S3 specifically includes the following sub-steps: S31, determining a failure threshold of the pressure in the packaging cavity; S32. Determine the failure time based on the prediction model and the failure threshold.

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