JP7470373B2 - Leak inspection method and leak inspection device - Google Patents

Description

The present invention relates to a leak inspection method and leak inspection device that calculates the amount of leakage from an electronic component that contains a piezoelectric element and inspects for leakage.

Small electronic components with piezoelectric elements sealed inside a package are sealed by creating a vacuum inside the package or by injecting an inert gas into the package in order to maintain the performance of the circuit. Leak testing is then carried out to ensure that the package is securely sealed and that no leaks have occurred. There are two types of leak testing: gross leak testing, which checks for large leaks, and fine leak testing, which checks for small leaks.

Gross leak tests include, for example, a bubble leak test in which a package is submerged in hot water to expand the inside, and if the sealing is insufficient, the expanded air leaks as bubbles and is visually confirmed to leak out, and an air leak test described in Patent Document 1 in which a leak-free reference object and a leaking test object are placed in two sealed containers and pressurized, the pressure on the leaking test object decreases, and a leak is determined by observing the pressure difference that occurs between the reference object and the test object. Fine leak tests, for example, are tests to confirm the presence of a microhole by pressurizing the package in an inspection container filled with helium gas, forcing helium gas into the package through the microhole if there is one, and then reducing the pressure inside the inspection container to measure the helium gas leaking from the package.

In gross leak testing, bubble leak testing is unreliable because it is visually checked, and air leak testing is unable to detect minute leaks. Helium leak testing, which is a fine leak test, has the advantage of being highly sensitive to leaks, but it is time-consuming because it is performed using helium gas, and it is also difficult to detect large leak holes, so it must be used in conjunction with a gross leak tester. In addition, multiple simultaneous processing is required to reduce processing time, making it difficult to determine leaks for each electronic component being tested. For example, if a large number of items are tested simultaneously for helium leaks and defects are found, they are divided into several groups and helium leak testing is performed on each group again. The group in which a leak was found is further divided into groups, and a helium leak test is performed. This retest is repeated to find the leaking electronic component. Since the retest is performed without refilling with helium, depending on the amount of leakage, the helium may escape and the defective products may not be identified, and they will be discarded together with the good products as a group containing defects. Furthermore, performing both gross leak testing and fine leak testing with one device requires a large dedicated device.

On the other hand, leak testing may be performed using changes in the impedance of a piezoelectric element. This testing method utilizes the fact that the impedance of a piezoelectric element changes with pressure. For example, as disclosed in Patent Document 2, a piezoelectric element is placed in an inspection chamber and reduced pressure from atmospheric pressure is applied. If there is no change in the impedance of the piezoelectric element due to the reduced pressure, it is determined that there is no leak, and if there is a change in impedance, it is determined that there is a leak. In Patent Document 3, an electronic component is pressurized from atmospheric pressure, and if the amount of change in impedance is equal to or greater than a set value, it is determined that there is a leak. In Patent Document 4, an airtight sealing chamber and an inspection chamber are provided in series, and the crystal impedance (hereinafter referred to as the "CI value") in the vacuum atmosphere after vacuum sealing is compared with the CI value in the pressurized atmosphere inspection chamber to test for leaks.

Japanese Patent Application Laid-Open No. 49-59692 Japanese Patent Application Laid-Open No. 11-51802 International Publication No. 2008/038383 JP 2012-257152 A

When the leak inspection method disclosed in Patent Document 2 or Patent Document 3 is used for leak inspection, it is possible to check for the presence or absence of leaks, but it is not possible to accurately measure the amount of leaks. When a piezoelectric element is released to the atmosphere after vacuum sealing, the pressure inside the package of the piezoelectric element gradually increases through the leak hole. If the amount of leak is extremely small, it takes a long time for the pressure inside the package to become equal to the external pressure, so the pressure inside the package and the external pressure often do not match when the leak inspection begins. When a piezoelectric element released to the atmosphere after vacuum sealing is leak inspected using the method of Patent Document 2 or Patent Document 3, the initial value of the pressure inside the package is unknown, and the amount of leak cannot be calculated. Even when leak inspection of a piezoelectric element is repeated, the internal pressure at the start of the measurement differs depending on the history of exhaust or pressurization, so the amount of change in the CI value differs, and the amount of leak cannot be calculated from the amount of change in the CI value.

In Patent Document 4, the CI value is measured without releasing the pressure to the atmosphere after vacuum sealing, so the CI value measured at a known pressure inside the package can be used as a reference, and the initial pressure inside the package can be accurately obtained, making it possible to calculate the amount of leakage from the amount of change in the CI value. However, a vacuum must be maintained from vacuum sealing to leakage testing, and the vacuum sealing device and the testing device must be connected with a vacuum chamber, which causes a problem of the device becoming larger. In addition, in order to connect the sealing device and the testing device, it is necessary to share a tray for storing piezoelectric elements or to provide a separate transfer machine, and it is not easy to connect the testing device to an existing vacuum sealing device. Furthermore, for piezoelectric elements whose CI value could not be measured in a vacuum due to a malfunction of the device or defective products returned after shipping, it is difficult to calculate the amount of leakage after removing them under atmospheric pressure, as in Patent Document 2 or Patent Document 3.

In inspection methods that can only tell whether or not there is a leak, electronic components that have a leak are deemed defective. However, even if there is a leak, as long as the amount of leak is within a certain tolerance, it will not have a significant effect on the performance of the electronic component. If the amount of leak can be calculated, the tolerance for the amount of leak can be determined, which will improve product yield, so it is important to calculate the amount of leak.

The present invention was made in consideration of the above-mentioned circumstances, and aims to provide a leak inspection method that can not only determine the presence or absence of leakage from electronic components, but also calculate the amount of leakage from the electronic components, and a leak inspection device that is small, easy to incorporate into existing devices, and has a high degree of design freedom.

A leak inspection method according to a first aspect of the present invention includes:
A leak inspection method for calculating a leak amount of an electronic component in which a piezoelectric element is sealed, comprising the steps of:
an impedance change acquisition step of placing the electronic component in an atmosphere having a pressure lower than the internal pressure of the electronic component for a first predetermined time, acquiring a first impedance change of the piezoelectric element, and placing the electronic component in an atmosphere having a pressure higher than the internal pressure of the electronic component for a second predetermined time, acquiring a second impedance change of the piezoelectric element;
and a leakage amount calculation step of calculating an amount of leakage of gas leaking from the electronic component from a change in the first impedance and a change in the second impedance.

the change in the first impedance is a first gradient that indicates the change in the first impedance by a gradient;
the change in the second impedance is a second gradient that indicates the change in the second impedance by a gradient;
A leakage amount of the electronic component may be calculated from the first gradient and the second gradient.

The relationship between the time per unit time of the first predetermined time and the change in impedance may be obtained, or the relationship between the time per unit time of the second predetermined time and the change in impedance may be obtained, and the amount of leakage of the electronic component may be calculated from the obtained relationship.

The impedance change acquisition step includes:
an impedance change amount calculation step of forming a decompression curve formed from the relationship between the change in the first impedance and time and a pressurization curve formed from the relationship between the change in the second impedance and time, and determining an impedance change amount (ΔZ) based on changes in impedance values at two different points on the decompression curve or based on changes in impedance values at two points that are the same as the impedance values at the two points on the pressurization curve;
a time change calculation step of calculating a first time change (Δt _d ) based on the times corresponding to the impedance values at the two points on the depressurization curve, and calculating a second time change (Δt _u ) based on the times corresponding to the impedance values at the two points on the pressurization curve;
a pressure gradient ratio calculation step of calculating a pressure gradient ratio ( _γ ) which is a ratio between a decompression pressure gradient indicating a gradient of the decompression curve and a pressurization pressure gradient indicating a gradient of the pressurization curve, from the impedance change amount (ΔZ), the first time change amount (Δt _d ), and the second time change amount (Δt u );
The leakage amount calculation step includes:
The internal pressure (P _s ) of the electronic component may be calculated from the pressure gradient ratio (γ), and the leakage amount (Q) of the gas leaking from the electronic component may be calculated from the internal pressure (P _s ) and the elapsed time.

In the pressure reduction curve, the impedance value changes from _Zx to _Zs , which are the impedance values of the two points, and the time changes from a first time corresponding to _Zx to a second time corresponding to _Zs ;
In the pressurization curve, the impedance value changes from _Zs to _Zx , which are the impedance values of the two points, and the time changes from a third time corresponding to _Zs to a fourth time corresponding to _Zx ;
The second time and the third time may be the same time.

The pressure gradient ratio (γ) is
Calculated by γ=(ΔZ/Δt _d )/(ΔZ/Δt _u ),
(ΔZ is the impedance change amount, Δt _d is the first time change amount, and Δt _u is the second time change amount)
The internal pressure ( _Ps ) is
_Ps is calculated by ( _γPh + _Pl )/(γ+1),
(P _h is the pressure value when pressurized, and P _l is the pressure value when depressurized)
The leakage amount (Q) is
It may be calculated as Q=-V.DELTA.P.multidot.P _{atm /(Ps-Pl).DELTA.t} or _{Q =} V.DELTA.P.multidot.P _{atm /(Ph-Ps).DELTA.t} .
(V is the internal volume of the piezoelectric element, P _atm is the atmospheric pressure, and Δt is the elapsed time.)

A leak inspection device according to a second aspect of the present invention comprises:
A leak inspection device that calculates the amount of leakage from an electronic component in which a piezoelectric element is sealed, comprising:
a pressure reducing means for reducing the pressure of a first testing space in which the electronic component is placed;
a pressurizing means for pressurizing a second testing space in which the electronic component is placed;
an impedance change acquisition unit that measures the impedance of the piezoelectric element of the electronic component placed in the first and second testing spaces to acquire a change in impedance, the impedance change acquisition unit measuring the impedance of the piezoelectric element to acquire a first change in impedance after placing the electronic component in the first testing space depressurized by the depressurizing means for a first predetermined time, and measuring the impedance of the piezoelectric element to acquire a second change in impedance after placing the electronic component in the second testing space pressurized by the pressurizing means for a second predetermined time;
and a leakage amount calculation unit that calculates a leakage amount of gas leaking from the electronic component from the change in the first impedance and the change in the second impedance acquired by the impedance change acquisition unit.

The impedance change acquisition unit is
an impedance change amount calculation unit that forms a decompression curve formed from the relationship between the change in the first impedance and time and a pressurization curve formed from the relationship between the change in the second impedance and time, and determines an impedance change amount based on changes in impedance values at two different points on the decompression curve or based on changes in impedance values at two points that are the same as the impedance values at the two points on the pressurization curve;
a time change amount calculation unit that calculates a first time change amount based on the times corresponding to the impedance values at the two points on the depressurization curve, and calculates a second time change amount based on the times corresponding to the impedance values at the two points on the pressurization curve;
a pressure gradient ratio calculation unit that calculates a pressure gradient ratio, which is a ratio between a decompression pressure gradient indicating a gradient of the decompression curve and a pressurization pressure gradient indicating a gradient of the pressurization curve, from the impedance change amount, the first time change amount, and the second time change amount,
The leak amount calculation unit is
The internal pressure of the electronic component may be calculated from the pressure gradient ratio, and the amount of gas leaking from the electronic component may be calculated from the internal pressure and elapsed time.

The first testing space and the second testing space may be the same testing space, which may be formed in the same testing chamber, and the pressure reducing means and the pressure applying means may be connected to the testing chamber.

The present invention provides a leak inspection method that can not only determine whether an electronic component is leaking, but also calculates the amount of leakage from the electronic component, and a leak inspection device that is small, easy to incorporate into existing equipment, and has a high degree of design freedom.

1A and 1B show a quartz crystal resonator for which a leakage amount is calculated by a leakage amount calculation method according to an embodiment, in which (a) is a plan view of the quartz crystal resonator with a lid removed, and (b) is a cross-sectional view taken along line AA in (a). FIG. 13 is a diagram showing a change in external pressure of a quartz crystal resonator over time in a reference example. FIG. 13 is a diagram showing the relationship between the amount of leakage and the amount of change in impedance corresponding to the standing time in a reference example. FIG. 11 is a diagram showing the relationship between the actual leak amount and the measured value of the He flow rate in a helium leak test. 1 is a diagram showing a change in pressure inside a package of a quartz crystal oscillator when the inside of the package is depressurized for a certain period of time and then pressurized. 1 is a diagram showing a change in pressure inside a package of a quartz crystal oscillator when the inside of the package is pressurized for a certain period of time and then depressurized. 1 is a diagram showing the principle of a leak inspection method according to an embodiment of the present invention; FIG. 11 is a diagram showing the relationship between the pressure change when the pressure inside a package of a quartz crystal oscillator is reduced and then increased, the ratio of the time change to the amount of pressure change, the ratio of the time change to the amount of impedance change, and the pressure gradient ratio. 11A to 11C are diagrams illustrating another principle of the leak inspection method according to the present embodiment. FIG. 1 is a conceptual diagram of a leak inspection device. FIG. 2 is a block diagram of a leak inspection device. 1 is a flowchart of a leak inspection method. 1A shows an example of using the leak inspection device according to the present embodiment in a downstream process of a vacuum sealing device, and FIG. 1B shows an example of using the leak inspection device according to a comparative example in a downstream process of a vacuum sealing device.

The following describes in detail the embodiments of the leak inspection device and measurement method according to the present invention with reference to the attached drawings. Note that the embodiments described below are for illustrative purposes only and do not limit the scope of the present invention. Therefore, a person skilled in the art may adopt embodiments in which each or all of these elements are replaced with equivalents, and these embodiments are also within the scope of the present invention.

(Structure of a quartz crystal unit)
A piezoelectric element used in a leak inspection method and a leak inspection device according to an embodiment of the present invention will be described using a quartz crystal resonator as an example. Although up, down, left, and right directions are defined in the drawings, these terms are used to describe the present embodiment, and do not limit the directions when the embodiment of the present invention is actually used. Furthermore, the technical scope described in the claims should not be interpreted in a limited manner by these terms.

Figure 1 shows a quartz crystal oscillator used in the leak inspection method and inspection device according to this embodiment, where (a) is a top view of the quartz crystal oscillator with the cover removed, and (b) is a cross-sectional view of the quartz crystal oscillator in (a) taken along line A-A with the cover attached.

The quartz crystal unit 1 comprises a quartz crystal piece 10 and a package 20 that houses the quartz crystal piece 10. The package 20 comprises a base 21 and a lid 22 that closes an opening on the top surface of the base 21. By closing the opening on the top surface of the base 21 with the lid 22, an airtight space that is the inspection space is formed.

On both opposing principal surfaces of the crystal blank 10, excitation electrodes 11a, 11b made of a thin metal film for applying a voltage to the crystal blank 10 are formed by vapor deposition or sputtering. One end of the excitation electrodes 11a, 11b is connected to internal electrodes 211c, 211d of the base 21 (described later) on the underside of the crystal blank 10 via a conductive adhesive 13. As the conductive adhesive 13, for example, an adhesive with a silicone resin base material is used.

The base 21 is made of a material such as metal, ceramic, glass, quartz, or resin, and is a box-shaped member with a space for inserting the quartz crystal piece 10 inside and an open top as shown in FIG. 1(b). The base 21 has a bottom 211 and a wall 212 standing upright from the periphery of the bottom 211. A pair of external electrodes 211a, 211b for electrically connecting to an external circuit board or the like are attached to the lower surface of the bottom 211. A pair of internal electrodes 211c, 211d are attached to the bottom surface inside the base 21, and the internal electrode 211c and the excitation electrode 11a, and the internal electrode 211d and the excitation electrode 11b are connected via a conductive adhesive 13. The internal electrodes 211c and 211d are electrically connected to the external electrodes 211a and 211b, and the excitation electrodes 11a and 11b are connected to the internal electrodes 211c and 211d, so that the excitation electrodes 11a and 11b are electrically connected to the external electrodes 211a and 211b, respectively.

The lid 22 is a plate-like member made of a material such as metal, ceramic, glass, quartz, or resin, and closes the opening at the top of the base 21 to form an airtight space. A bonding material 23 such as silver solder, gold-tin, or nickel plating is applied to the top surface of the base 21, i.e., the top surface of the wall portion 212. The bonding material 23 and the lid 22 are bonded together by heating and melting them, and the package 20 is hermetically sealed.

In today's miniaturized crystal resonators, the inside of the package 20 of the crystal unit 1 is hermetically sealed under a vacuum. As mentioned above, there are methods for inspecting whether or not there is a leak in the electronic component in order to check whether or not the electronic component is being kept sealed. However, in order to ensure product yield, it is important to know the amount of leakage in addition to whether or not there is a leakage.

The principle of the leakage amount calculation method described in this embodiment will be explained while comparing it with a reference example. The leakage amount calculation method of this embodiment utilizes the characteristic that the impedance of a quartz oscillator increases with pressure due to friction between the quartz oscillator and gas molecules. The impedance of a quartz oscillator increases in proportion to the pressure in the molecular flow region, and increases in proportion to the 1/2 power of the pressure in the viscous flow region. Therefore, by measuring the change in impedance, the change in pressure inside the quartz oscillator package (hereinafter referred to as "internal pressure") can be determined, and by recognizing the change in internal pressure, it can be determined that a leak has occurred.

(Explanation of the reference example)
As a method for testing the presence or absence of leakage from the change in impedance of a quartz crystal unit, for example, there is a method (hereinafter referred to as "Reference Example 1") in which a quartz crystal blank is vacuum-sealed in a package, then removed to atmospheric pressure, the CI value of the quartz crystal is measured, the package is then placed in an inspection chamber to reduce pressure, the CI value is measured again, and the change in CI value is used to detect the pressure change and determine whether or not there is a leakage. There is also a method (hereinafter referred to as "Reference Example 2") in which a quartz crystal blank is vacuum-sealed in a package, then removed to atmospheric pressure, the CI value is measured, the package is then placed in an inspection chamber to increase pressure, the CI value is measured again, and the change in CI value is used to detect the pressure change and determine whether or not there is a leakage. These two methods for testing the presence or absence of leakage (Reference Examples 1 and 2) can test the presence or absence of leakage, but cannot measure the amount of leakage.

The reason why Reference Examples 1 and 2 cannot measure the amount of leakage will be explained using Reference Example 2. Figure 2 is a graph showing the relationship between the pressure outside the package (atmospheric pressure) and the elapsed time (t) when a quartz crystal oscillator sealed in a vacuum package containing a quartz crystal piece is left at atmospheric pressure for a certain period (t1) and then pressurized for a certain period (Δt2) to measure the CI value. If there is a leak in the quartz crystal oscillator, the size of the leak hole differs from one individual to another, so the internal pressure of each quartz crystal oscillator after the atmospheric pressure exposure time (t1) will be different. Even if the atmospheric pressure exposure time (t1) differs depending on the measurement order of each quartz crystal oscillator, the initial value of the internal pressure before pressure is applied will be different for each quartz crystal oscillator.

FIG. 3 is a graph showing the relationship between the amount of leakage (unit: Pam ² /s) and the amount of change in CI value (ΔZ: unit (Ω)) according to different leaving times. In a package with an internal volume V of 5E-12 m ³ , pressure of 2.5E+5 Pa was applied. Four patterns of leaving time (t1) were set, namely, 10 seconds, 60 seconds, 180 seconds, and 600 seconds, and the pressurization time (Δt2) was the same as 120 seconds. When the leaving time (t1) was 10 seconds and 60 seconds, the CI value also increased as the amount of leakage increased, but when the amount of leakage exceeded a certain value, a peak curve was shown in which the amount of leakage decreased, and the amount of leakage was not uniquely determined from the amount of change in the CI value. In addition, even if the amount of leakage is the same, the amount of change in the CI value (ΔZ) differs depending on the initial value of the internal pressure. The amount of leakage cannot be measured even if the amount of change in the CI value (ΔZ) is calculated. This situation is similar to Reference Example 1.

Furthermore, even if a helium leak test, which is a fine leak test, is used, the amount of leakage cannot be measured accurately. In a helium leak test, the quartz crystal oscillator to be tested is placed in an inspection chamber called a bombing chamber, where it is pressurized for a certain period of time. If there is a leak in the quartz crystal oscillator, this pressurization will cause helium gas to enter the inside of the quartz crystal oscillator through the leak. Hereinafter, the time it takes to pressurize the inspection chamber for a certain period of time and allow helium gas to enter the inside of the quartz crystal oscillator will be referred to as the filling time. After that, the inspection chamber is depressurized to create a vacuum inside the inspection chamber, and the helium gas that has entered the inside of the quartz crystal oscillator is released into the inspection chamber, so the helium gas that has leaked from the quartz crystal oscillator can be measured with a helium detector.

In helium leak testing, there is a set time between filling the quartz oscillator with helium gas and measuring it with a helium detector. In areas where the amount of leakage from the quartz oscillator is large, helium gas escapes from the quartz oscillator during this time, so the measured flow rate of helium gas may be low. In areas where the amount of leakage is small, for example, with a filling time of about 60 minutes, helium gas may not be sufficiently filled into the quartz oscillator, so the measured flow rate of helium gas may be low. When the amount of leakage is 1/10, the amount of helium filled will be 1/10, so the measured helium flow rate will be 1/100. The flow rate of helium decreases as the square of the amount of leakage.

In addition, when a retest is performed in a helium leak test, the quartz crystal oscillator must be refilled with helium gas, and in areas with a small amount of leakage, the helium pressure increases after each refill, and the helium gas flow rate is measured to be large each time a retest is performed.

In order to consider the relationship between the actual leak amount and the theoretical leak amount, a quartz crystal unit was placed in a container filled with helium gas pressurized at a pressure of 0.5 MPa, and after leaving it for 60 minutes, the amount of helium gas leak was measured, as shown in Figure 4. The internal volume V of the package was 1.E-10 ^m3 . In this measurement, the time from filling to starting the measurement was set to 1 minute, and the time from measurement to starting refilling for 60 minutes was set to 1 minute.

The graph shown in FIG. 4 shows the relationship between the theoretical value of the leak amount, the actual leak amount measured at the first time, the actual leak amount measured at the second time after refilling helium gas, and the actual leak amount measured at the fifth time after refilling helium gas, and the helium measurement value (unit: Pa·m ³ /s). The actual leak amount is shown in accordance with JIS (unit: Pa·m ³ /s) in dry air at atmospheric pressure. The theoretical value of the leak amount corresponds to the amount of helium leaking from inside the package immediately after filling the package with helium gas after a sufficiently long time has elapsed until the helium pressure inside and outside the package become equal. Since the conductance of the leak part of the quartz crystal unit is the square root of the molecular weight ratio, helium gas has a conductance 2.7 times that of air, and when 5 atmospheres of helium gas is filled into the package, a flow rate 13.5 times that of air (2.7×5=13.5 times) is measured. Therefore, the theoretical value of the helium leak amount can be expressed as air leak amount×2.7×5.

As can be seen from the graph in Figure 4, the actual leak amount overlaps with the theoretical leak amount, and the range of the actual leak amount that can be measured with high accuracy is extremely limited, as shown by the dotted line. In this way, when using the leak test using the CI value or the helium leak test described above, it is possible to determine whether or not there is a leak, but it is not possible to accurately measure the leak amount.

(Principle of the leakage amount calculation method according to the present embodiment)
The leakage amount calculation method of the present embodiment is characterized in that the leakage amount can be calculated by estimating the internal pressure of the quartz crystal resonator in a leakage inspection method using a CI value (hereinafter also referred to as impedance).

The CI value in high vacuum is a CI value (hereinafter referred to as " _Z0 value") specific to the quartz crystal unit and is not dependent on the gas pressure, and the sum of this and the amount of change in the CI value due to the gas pressure (ΔZ) is the CI value at a certain pressure. However, this _Z0 value differs for each individual quartz crystal unit. On the other hand, if the pressure is known, such as the CI value in high vacuum or atmospheric pressure, it is possible to convert the pressure from the amount of change in the CI value, so if the internal pressure of the quartz crystal unit is known, it is possible to convert the change in pressure from the change in the CI value. If the change in pressure is known, the amount of leakage can be calculated.

The applicant placed the quartz crystal oscillator under reduced pressure for a predetermined period of time and then applied pressure, or placed the quartz crystal oscillator under pressure for a predetermined period of time and then applied pressure, and calculated the internal pressure from the difference in pressure change when reduced pressure was applied and when pressurized, and derived the amount of leakage from the internal pressure.

The relationship between pressure change during decompression and pressure change during pressurization will be explained with reference to Figures 5 and 6. Figure 5 shows the pressure change inside the package of a quartz oscillator when the quartz oscillator is placed under reduced pressure for a fixed period of time, the inside of the package is evacuated (reduced pressure), and then pressurized, while Figure 6 shows the pressure change inside the package of a quartz oscillator when the quartz oscillator is placed under pressure for a fixed period of time, the inside of the package is pressurized, and then decompressed. In Figures 5 and 6, the "fixed time" when decompressing or pressurizing for a fixed period of time was calculated for three patterns: 7.5 minutes, 65 minutes, and 200 minutes.

As shown in Figures 5 and 6, the slope (gradient) of the pressure curve showing the pressure change during decompression (hereafter referred to as the "decompression curve") is different from the slope (gradient) of the pressure curve showing the pressure change during pressurization (hereafter referred to as the "pressurization curve"). As shown in Figure 5, when the exhaust time is short and the internal pressure of the package is high, the pressure gradient of the decompression curve is larger than the pressure gradient of the pressurization curve. When the exhaust time is long and the internal pressure of the package is low, the pressure gradient of the decompression curve is smaller than the pressure gradient of the pressurization curve. As shown in Figure 6, when the pressurization time is short and the internal pressure of the package is low, the pressure gradient of the pressurization curve is larger than the pressure gradient of the decompression curve. When the pressurization time is long and the internal pressure of the package is high, the pressure gradient of the pressurization curve is smaller than the pressure gradient of the decompression curve. Focusing on this characteristic, the internal pressure of the quartz crystal unit can be calculated as follows.

7 is a graph showing the change in pressure inside the package when a quartz crystal unit is left in an inspection chamber under reduced pressure _P1 for a predetermined time ( _ts1 ), and the pressure inside the package of the quartz crystal unit becomes pressure _Ps , and then the quartz crystal unit is left in an inspection chamber under pressure _Ph for a predetermined time. Here, P1 _, Ps _{, and Ph} have a relationship of _P1 < _Ps , _Ph > _Ps . The horizontal axis of the graph shows elapsed time (t), and the vertical axis shows pressure (P) or impedance (Z). The graph shows a decompression curve a that is decompressed for a predetermined period and then descends, and a pressurization curve b that is pressurized after a predetermined period and then ascends. In order to obtain the slope (gradient) of the decompression curve a and the pressurization curve b of the graph, the amount of change between the pressure value ( _Px ) and the pressure value ( _Ps ) that are the same pressure value on the decompression curve a and the pressurization curve b is defined as _ΔPd for the decompression curve a, and _ΔPu for the pressurization curve. _ΔPd and _ΔPu are the same value, and the relationship of ΔP as a representative value is _ΔPd = _ΔPu = ΔP. In the decompression curve a, the amount of time change between the time ( _tx1 ) corresponding to the same pressure value ( _Px ) and the time ( _ts1 ) corresponding to the same pressure value ( _Ps ) is defined as _Δtd (hereinafter referred to as the "first time change amount"), and in the pressurization curve b, the amount of time change between the time ( _tx2 ) corresponding to the same pressure value ( _Px ) and the time ( _ts2 ) corresponding to the same pressure value ( _Ps ) is defined as _Δtu (hereinafter referred to as the "second time change amount"). It is also possible to switch from decompression to pressurization at _ts1 by making _ts1 = _ts2 .

The decompression pressure gradient (ΔP/Δt _d ), which is the inclination of the decompression curve a, is given by the following Equation 1.
ΔP/Δt _d = −C(P _s −P _l )/V (Equation 1)
The pressurization pressure gradient (ΔP/Δt _u ), which is the slope of the pressurization curve b, is expressed by the following formula 2.
ΔP/Δt _u = C(P _h - P _s )/V (Equation 2)
Here, V (m ³ ) is the internal volume of the crystal unit package, and C (m ³ /s) is the conductance of the leak hole in the package. The decompression pressure gradient is also called the first gradient, and the pressurization pressure gradient is also called the second gradient.

The ratio of the decompression pressure gradient of the decompression curve a to the pressurization pressure gradient of the pressurization curve b (hereinafter referred to as the “pressure gradient ratio (γ)”) is calculated by the following formula 3.
γ=(ΔP/Δt _d )/(ΔP/Δt _u ) (Equation 3)
γ=(ΔP/Δt _d )/(ΔP/Δt _u )=(P _s -P _l )/(P _h -P _s ), and the internal pressure (P _s ) of the quartz crystal unit can be calculated by the following equation 4.
_Ps = ( _γPh + _Pl ) / (γ + 1) (Equation 4)

Here, P _h and P _l are known values, and the internal pressure P _s can be found by determining the pressure gradient ratio γ, and the leak amount Q can be found as a flow rate at atmospheric pressure. That is, from Equations 1 and 2, the conductance C can be found by the following Equations 5 and 6.
C=−VΔP/(P _s −P _l )Δt (Equation 5)
C=VΔP/(P _h −P _s )Δt (Equation 6)
Since the flow rate (Q) at atmospheric pressure (P _atm ) is Q=CP _atm , the leakage amount (Q) can be calculated by the following formula 7 or 8.
Q = -VΔP·P _atm / (P _s -P _l ) Δt (Equation 7)
Q = V ΔP · P _atm / ( P _h - _{P s} ) Δt (Equation 8)

The pressure gradient ratio (γ) can be calculated as the ratio of the change in impedance when depressurizing to the change in impedance when pressurizing. As described above, the change in impedance of the quartz crystal unit corresponds to the change in pressure. From Equation 3, the pressure gradient ratio (γ) is γ=(ΔP/Δt _d )/(ΔP/Δt _u ), and when substituted for the change in impedance, it can be calculated by the following Equation 9.
γ=(ΔZ/Δt _d )/(ΔZ/Δt _u )=(ΔZ _d /Δt _d )/(ΔZ _u /Δt _u ) (Equation 9)
Here, ΔZ _d is referred to as a first impedance change amount, and ΔZ _u is referred to as a second impedance change amount. ΔZ _d and ΔZ _u are the same value, and the pressure gradient ratio (γ) is found using ΔZ as a representative value.

8 shows the relationship between the pressure change inside the package of the quartz crystal unit when the exhaust is interrupted midway and then pressurized, and the pressure gradient ratio γ=( _Ps - _Pl )/( _Ph - _Ps ), the ratio of ΔP/Δt (ΔP/ _Δtd )/(ΔP/ _Δtu ), and the ratio of the ratios of ΔZ/Δt (ΔZ/ _Δtd )/(ΔZ/ _Δtu ). As shown in the figure, the curves of the three graphs of the pressure gradient ratio γ, the ratio of ΔP/Δt, and ΔZ/Δt are almost the same, and it can be seen from this graph that the pressure gradient ratio (γ) can be found by calculating the amount of impedance change (ΔZ).

Therefore, by measuring the impedance of the quartz crystal unit, the pressure gradient ratio (γ) can be calculated using equation 9, and once the pressure gradient ratio (γ) is calculated, the internal pressure ( _Ps ) of the quartz crystal unit can be calculated using equation 4. As a result, it becomes possible to calculate the leakage amount (Q) using equation 7 or 8.

Furthermore, as shown in Fig. 9, by repeating the process multiple times (decompression-pressure-decompression...), multiple values of the internal pressure ( _Ps ) are obtained. By obtaining multiple values of the internal pressure ( _Ps ), the accuracy of the leakage amount calculation is improved. If the relationship between the multiple values of the internal pressure ( _Ps ) and the time and pressure is known, it is possible to obtain the leakage amount even if the relationship between the impedance change amount (ΔZ) and the pressure change amount (ΔP) is not known.

Also, a quartz crystal unit may be placed in an atmosphere of a predetermined pressure P _l (P _l < P _s ) to obtain the relationship between time and the internal pressure (P _s ), a quartz crystal unit may be placed in an atmosphere of a predetermined pressure P _h (P _h > P _s ) to obtain the relationship between time and the internal pressure (P _s ), and the leakage amount (Q) may be calculated from a plurality of values of the internal pressure (P _s ) and the leakage amount (Q) may be averaged or weighted according to the conditions. Specifically, the impedance value per unit time when the pressure is reduced and then pressurized, or when the pressure is reduced and then pressurized, may be obtained, and the internal pressure (P _s ) may be found by obtaining a decompression curve and a pressurization curve based on the impedance value. For example, any two points ( _Z1 , _Z2 , _Z1 > _Z2 ) with different impedance values are selected from each of the decompression curve and the pressurization curve, the time _Δtd from _Z1 to _Z2 on the decompression curve and the time Δt _u from _Z2 to _Z1 on the pressurization curve are calculated, and the internal pressure when the impedance value is _Z2 is found from the pressure gradient ratio (γ). If the impedance value per unit time is obtained, the two arbitrary points can be freely set, and the relationship between time and internal pressure ( _Ps ) can be known, making it possible to continuously calculate the leakage amount and enabling fine control.

(Leak inspection device)
Next, the leak inspection device will be described with reference to Fig. 10. Fig. 10 is a conceptual diagram of the leak inspection device, and the dimensions of the device are different from those of the actual device. In addition, the up, down, left, and right directions on the paper are defined as "up", "down", "left", and "right", but these are for the purpose of explanation and do not limit the directions when the embodiment of the present invention is actually used.

The leak inspection device 300 includes a stage 301 on which the quartz crystal oscillator 1 is mounted, a contact probe 302 for measuring the resonant frequency and impedance of the quartz crystal oscillator 1, a contact block 303 that holds the contact probe 302 and moves up and down, a measurement unit 304 for measuring the impedance of the quartz crystal oscillator 1, a pressure reducing means 305 for reducing the pressure in the internal space of the inspection chamber 400 formed between the stage 301 and the contact block 303, a pressurizing means 306 for pressurizing the internal space, a pressure gauge 400a for measuring the pressure in the inspection chamber 400, and a control unit 307 for controlling the overall operation of the leak inspection device 300. The configuration of the control unit 307 will be described later.

The quartz crystal oscillator 1 is housed in a rectangular tray 14, and the tray 14 is placed on the stage 301. The tray 14 has a plurality of holes (not shown) formed therein for housing the quartz crystal oscillator 1. The plurality of holes are formed in a matrix on the tray 14.

The stage 301 has a tray 14 containing the quartz crystal oscillator 1 placed on its upper surface. The space formed by the stage 301 and the contact block 303 forms the inspection chamber 400.

The contact probe 302 is a component that measures the resonant frequency and impedance of the quartz crystal unit 1, and has a pair of contact pins 302a, 302b at its tip. When the contact block 303, which will be described later, moves up and down, the contact pins 302a, 302b come into contact with the external electrodes 211a, 211b of the quartz crystal unit 1, and a voltage is applied to measure the resonant frequency and impedance.

The measurement unit 304 receives signals transmitted from the external electrodes 211a and 211b and measures the impedance of the quartz crystal oscillator 1. The measurement unit 304 uses, for example, a network analyzer. The measurement unit 304 measures the impedance of the quartz crystal oscillator 1 while the quartz crystal oscillator 1 is placed for a predetermined time in the inspection chamber 400 whose pressure is reduced by the pressure reduction means 305 described below, and while the inspection chamber 400 is pressurized for a predetermined time by the pressure reduction means 306 described below. The measurement unit 304 transmits the measured impedance value to the control unit 307.

The contact probe 302 is moved forward or backward toward the crystal unit 1 by a lifting mechanism (not shown). In this embodiment, the contact probe 302 moves up and down in the drawing. A spring (not shown) is inserted into the contact pins 302a, 302b or the contact probe 302. The contact pins 302a, 302b expand and contract due to the elastic force of the spring, so that in the forward state, the contact pins 302a, 302b are brought into contact with the external electrodes 211a, 211b of the crystal unit 1 while applying pressure. In addition, the contact block 303 moves backward to separate the contact pins 302a, 302b from the external electrodes 211a, 211b.

The pair of contact pins 302a, 302b of the contact probe 302 corresponds one-to-one to the pair of external electrodes 211a, 211b. The contact probes 302 are arranged in the same direction as any row of quartz crystal oscillators 1 arranged in a matrix on the tray 14, and the same number of pairs of contact pins 302a, 302b are arranged as the number of quartz crystal oscillators arranged in a row. The contact probes 302 may be arranged so as to come into contact with all of the quartz crystal oscillators 1 arranged in the matrix.

A gasket 308 is attached to the periphery of the underside of the contact block 303 to strengthen the airtightness between it and the stage 301. When the contact block 303 descends and comes into contact with the stage 301, the inspection chamber 400 is sealed.

The pressure reducing means 305 is specifically a vacuum pump, and reduces the pressure inside the inspection chamber 400 by opening and closing a gate valve (not shown) installed in the flow path of the vacuum pump.

The pressurizing means 306 is a device that sends gas at a predetermined pressure into the inspection chamber 400. In this embodiment, for example, compressed nitrogen gas is introduced into the inspection chamber 400 from the pressurizing means 306. In this embodiment, the pressurizing means 306 pressurizes the inside of the inspection chamber 400 that has been depressurized by the depressurizing means 305 for a predetermined period of time.

The control unit 307 includes a CPU, a storage device, etc. For example, the CPU executes a program stored in the storage device, performs various processes based on data stored in the storage device, and controls the overall operation of the leak inspection device 300.

As shown in FIG. 11, the control unit 307 includes an impedance change amount calculation unit 309, a time change amount calculation unit 310, a pressure gradient ratio calculation unit 311, and a leak amount calculation unit 312. The impedance change amount calculation unit 309, the time change amount calculation unit 310, and the pressure gradient ratio calculation unit 311 constitute an impedance change acquisition unit.

The impedance change amount calculation unit 309 calculates the amount of change in impedance based on the impedance value measured by the measurement unit 304. Specifically, the impedance change amount calculation unit 309 forms a decompression curve and a pressurization curve that are defined by the relationship between the change in impedance and time based on the impedance value measured by the measurement unit 304. Then, the impedance change amount is calculated in the decompression curve and the pressurization curve. As shown in FIG. 7, the impedance change amount is calculated by determining impedance values (Z _x , Z _s ) at the same two points in the decompression curve a and the pressurization curve b. In the decompression curve a, the amount of change in impedance between an arbitrary impedance value (Z _x ) and the impedance value (Z _s ) when the quartz crystal resonator 1 is placed in the decompressed inspection chamber 400 for a predetermined period (t _s1 ) is defined as a first impedance change amount (ΔZ _d ). In addition, in the pressurization curve b, the change in impedance between the impedance value ( _Zs ) when the quartz crystal resonator 1 is placed in the inspection room 400 for a predetermined period ( _ts2 ) and an arbitrary impedance value ( _Zx ) is defined as a second impedance change ( _ΔZu ). Since the first impedance change ( _ΔZd ) and the second impedance change ( _ΔZu ) are the same value, the representative value is defined as the impedance change (ΔZ).

The impedance change amount (ΔZ) is ideally determined based on the impedance values (Z _x ) (Z _s ) of the same two points on the depressurization curve a and the pressurization curve b, but may be determined based on the impedance values of two non-identical points on the depressurization curve a and the pressurization curve b. When the two corresponding impedance values on the depressurization curve a and the pressurization curve b are close to each other, the two values are approximated to the same impedance value (Z _x ) or (Z _s ) and used as the reference impedance value. When the two corresponding impedance values are far apart, a conversion formula prepared separately is used to determine the same impedance value (Z _x ) or (Z _s ) and use it as the reference impedance value.

The time change calculation unit 310 calculates the change in time corresponding to the impedance change amount (ΔZ). The time change calculation unit 310 determines the amount of time change between a first time (t _x1 ) and a second time (t _s1 ) corresponding to two impedance values (Z _x , Z _s ) on the depressurization curve a as a first time change amount (Δt _d ), and determines the amount of time change between a third time (t _s2 ) and a fourth time (t _x2 ) corresponding to two impedance values (Z _x , Z _s ) on the pressurization curve b as a second time change amount (Δt _u ).

In the times corresponding to the impedance values at two points, the second time _ts1 and the third time _ts2 may be the same time. If the same time is _ts , the first time change ( _Δtd ) and the second time change ( _Δtu ) can be calculated using the three values _tx1 , _ts , and _tx2 , thereby speeding up the processing.

The pressure gradient ratio calculation unit 311 calculates the pressure gradient ratio (γ) from the impedance change amount (ΔZ), the first time change amount (Δt _d ), and the second time change amount (Δt _u ) using Equation 9.

The leak amount calculation unit 312 calculates the internal pressure ( _Ps ) of the quartz crystal oscillator 1 from the pressure gradient ratio (γ) using equation 4, and calculates the amount of gas leaking from the quartz crystal oscillator 1 using equation 7 or 8 from the calculated internal pressure ( _Ps ) and the elapsed time (Δt).

(How to calculate the amount of leakage)
A method for calculating the amount of leakage using the leakage inspection device 300 will be described with reference to the flowchart of FIG.

A tray 14 carrying multiple crystal oscillators 1 is brought into the inspection chamber 400 of the leak inspection device 300 shown in FIG. 10 and placed on the stage 301. The contact block 303 is then lowered to bring the peripheral portion of the contact block 303 into close contact with the upper surface of the stage 301, forming an airtight space between the contact block 303 and the stage 301. Then, the contact pins 302a and 302b of the contact probe 302 are lowered to contact the external electrodes 211a and 211b of the crystal oscillator 1, and calculation of the leak amount begins.

First, the pressure in the inspection chamber 400 is reduced by the pressure reducing means 305, and the quartz crystal oscillator 1 is placed in the inspection chamber 400 for a first predetermined time. Thereafter, the pressure in the inspection chamber 400 is increased by the pressure applying means 306, and the quartz crystal oscillator 1 is placed in the inspection chamber 400 for a second predetermined time. The pressure in the inspection chamber 400 is monitored by the pressure gauge 400a. The measurement unit 304 measures the impedance of the quartz crystal oscillator 1 for the first predetermined time and the second predetermined time (step S101).

Then, the impedance change calculation unit 309 forms a decompression curve a and a pressurization curve b based on the measured impedance, and calculates a first impedance change (ΔZ _d ) and a second impedance change (ΔZ _u ), i.e., the impedance change (ΔZ) (step S102) (impedance change calculation process).

The time change calculation unit 310 calculates a first time change (Δt _d ) and a second time change (Δt _u ) from the impedance change (ΔZ) (time change calculation step), and the pressure gradient ratio calculation unit 311 calculates a pressure gradient ratio (γ) using equation 9 (step S103) (pressure gradient ratio calculation step). The impedance change calculation step, time change calculation step, and pressure gradient ratio calculation step constitute an impedance change acquisition step.

The leak amount calculation unit 312 calculates the internal pressure ( _Ps ) of the quartz crystal unit 1 using Equation 4 based on the pressure gradient ratio (γ) obtained by the pressure gradient ratio calculation unit 311 (step S104), and calculates the leak amount (Q) using Equation 7 or Equation 8 based on the internal pressure ( _Ps ) (step S105) (leak amount calculation process).

(Example of using a leak inspection device)
Next, an example of using the leak inspection device according to the present embodiment will be described. When manufacturing electronic components, such as a quartz crystal unit, the leak inspection device according to the present embodiment is used, for example, after the quartz crystal unit is vacuum sealed. The characteristics of the leak inspection device according to the present embodiment when used after the vacuum sealing process will be described with reference to a comparative example.

Figure 13 shows an example of use when a leak inspection device is installed in the process downstream of a vacuum sealing device. Figure 13(a) is a diagram showing the state in which the leak inspection device of this embodiment is connected to a vacuum sealing device, and Figure 13(b) is a diagram showing the state in which a leak inspection device of a comparative example is connected to a vacuum sealing device. The figure only shows the state in which the vacuum sealing device and the leak inspection device are connected, and does not show the process upstream of the vacuum sealing device.

In the comparative example, as shown in FIG. 13(b), the vacuum sealing device 500 and the leak inspection device 503 are connected via the removal chamber 501 and the vacuum chamber 502. The vacuum sealing device 500 is equipped with an exhaust means (not shown), and performs vacuum sealing of the crystal oscillator 1 while transporting a transport tray 504 carrying a plurality of crystal oscillators 1 in the vacuum atmosphere formed by the exhaust means. The vacuum sealing device 500 is equipped with a heating and pressurizing device 505 that heats and pressurizes the crystal oscillator 1, and a cooling device 506 that cools the crystal oscillator 1. The crystal oscillator 1 is sandwiched between the heating and pressurizing members in the heating and pressurizing device 505 and heated and pressurized in a state in which the bonding material 23 is applied between the base 21 and the lid 22, and the base 21 and the lid 22 are bonded (see FIGS. 1(a) and 1(b) for the specific structure of the crystal oscillator 1). The package 20 of the crystal oscillator 1 is hermetically sealed. The transport tray 504 is then sent to the cooling device 506, where the crystal oscillator 1 is cooled.

The vacuum chamber 502 is equipped with an exhaust means and a transfer section (not shown), and in a vacuum atmosphere, the crystal oscillator 1 transported from the vacuum sealing device 500 via the removal chamber 501 is transferred from the transport tray 504 to the inspection tray 507. In the case of seam welding, the crystal oscillator 1 is inverted. The crystal oscillator 1 mounted on the transport tray 504 and the inspection tray 507 is held down by the workpiece holder 508 so as not to shift on the transport tray 504 and the inspection tray 507 during movement.

The inspection tray 507 on which the quartz crystal oscillator 1 is mounted is transferred from the transfer section of the vacuum chamber 502 to the leak inspection device 503. The vacuum chamber 502 is equipped with an exhaust means (not shown), and is evacuated by the exhaust means to maintain a vacuum atmosphere.

The leak inspection device 503 includes a leak inspection section 503a and a storage section 503b that stores the leak inspection section 503a. Exhaust means and pressurizing means (not shown) are attached to the storage section 503b. The exhaust means creates a vacuum atmosphere inside the storage section 503b, and the quartz crystal oscillator 1 placed on the inspection tray 507 from the vacuum chamber 502 is carried into the leak inspection device 503. After the pressure means pressurizes the storage section 503b, the CI value of the quartz crystal oscillator 1 is measured by the leak inspection section 503a. The inspection tray 507 that has completed the inspection is carried out from the leak inspection device 503.

In the comparative example, the internal pressure of the quartz crystal resonator 1 vacuum-sealed by the vacuum sealing device 500 must be maintained and the leak inspection unit 503b must inspect it. This requires a vacuum chamber 502, and the capacity of the leak inspection device 503 must be large to maintain a vacuum atmosphere. The leak inspection device 503 requires a capacity of, for example, 50 liters. In addition, because the capacity of the leak inspection device 503 is large, it takes time to evacuate and pressurize the leak inspection device 503, which extends the tact time.

In addition, since it is necessary to place the vacuum chamber 502, the connection structure between the vacuum sealing device 500 and the leak inspection device 503 becomes complicated and large. When adding a leak inspection device 503 to an existing vacuum sealing device 500, it is not easy to maintain a vacuum between the vacuum sealing device 500 and the leak inspection device 503 because the vacuum sealing device 500 is not designed to be connected by vacuum, and significant modifications may be unavoidable.

On the other hand, FIG. 13(a) shows the case where the leak inspection device 300 according to this embodiment is connected to an existing vacuum sealing device 500. The configuration of the vacuum sealing device 500 is the same as in the comparative example, and the vacuum sealing device 500 includes a heating and pressurizing device 505 and a cooling device 506. The method of vacuum sealing the package 20 of the quartz crystal resonator 1 using the heating and pressurizing device 505 is also the same as in the comparative example, and a description thereof will be omitted.

The transport tray 504 containing the hermetically sealed quartz crystal oscillator 1 is transported from the vacuum sealing device 500 to the removal chamber 501, as in the comparative example. The transport tray 504 is then removed from the removal chamber 501, and the quartz crystal oscillator 1 is transferred from the transport tray 504 to the inspection tray 507 under atmospheric pressure. If necessary, the inspection tray 507 is inverted. The inspection tray 507 is transported into the leak inspection device 300, where it is inspected for leaks and then removed from the leak inspection device 300.

The leak inspection device 300 of this embodiment corresponds to the leak inspection section 503a of the comparative example, but does not need to be placed in a vacuum atmosphere. Therefore, it is only necessary to evacuate and pressurize the inside of the leak inspection device 300, which corresponds to the leak inspection section 503a. Specifically, it is only necessary to evacuate and pressurize the small space around the inspection tray 507, for example, an inspection chamber with a capacity of 40 milliliters, and it is possible to miniaturize the exhaust means and pressurization means. Since the internal capacity of the leak inspection device 300 is small, the exhaust and pressurization time is short, and the takt time is shortened. The leak inspection device 300 is small and low-cost, and can individually determine gross leaks and fine leaks with a single unit.

Furthermore, since the transfer to the inspection tray 507 is performed under atmospheric pressure, there is a high degree of freedom in design and it can be easily connected to an existing vacuum sealing device 500. Also, the vacuum chamber 502 and the storage section 503b are not required as in the comparative example, and the connection structure between the vacuum sealing device 500 and the leak inspection device 300 can be made compact and simple. Furthermore, since the CI value is measured by pressurizing to atmospheric pressure or higher using the CI value under a vacuum atmosphere as the reference, the amount of change in the CI value is large and the amount of leakage can be calculated with high accuracy.

This embodiment can not only determine whether a leak exists, but also calculate the amount of leakage, improving product yield.

According to this embodiment, the amount of leakage can be calculated from the change in impedance of the quartz crystal oscillator 1 under a pressure higher than the internal pressure and from the change in impedance of the quartz crystal oscillator 1 under a pressure lower than the internal pressure, so that the amount of leakage can be obtained appropriately in a simple manner.

According to this embodiment, the change in impedance of the quartz crystal resonator 1 is regarded as a gradient, and the amount of leakage can be obtained from the change in gradient, so the amount of leakage can be easily calculated using an existing measuring device, for example, a network analyzer.

According to this embodiment, the amount of leakage can be easily calculated from the time per unit time and the amount of change in impedance, and appropriate leakage testing can be performed.

According to this embodiment, the inspection device can be used for both gross leak inspections to check for large leaks and fine leak inspections to check for small leaks, simplifying the inspection device.

According to this embodiment, the amount of leakage can be calculated by leaving the quartz crystal resonator 1 in a reduced pressure or pressurized atmosphere for a predetermined time (ts), so the amount of leakage can be measured without taking the time required for helium leakage testing.

According to this embodiment, the leak amount can be calculated even if the history before the leak test is unknown, such as when the exhaust time or atmospheric exposure time before the test differs.

In this embodiment, the decompression means 305 and the pressurization means 306 are connected to one examination chamber 400, so there is no need to perform decompression and pressurization in separate examination chambers, making the device more compact.

According to this embodiment, the pressure is reduced and pressurized in the same examination room 400, and the impedance is measured continuously, so the CI value is not affected by the position of the contact pins 302a and 302b being shifted or the stroke of the contact pins 302a and 302b being changed.

In this embodiment, the decompression means 305 and the pressurization means 306 are installed in the same examination chamber 400, but they may also be installed in separate examination chambers.

In this embodiment, it has been described that the contact block 303 moves up and down, and the contact pins 302a, 302b move in and out of contact with the external electrodes 211a, 211b, but the stage 301 may also move up and down.

In this embodiment, a method of calculating the leakage amount by first reducing the pressure and then increasing the pressure has been described, but the leakage amount may also be calculated by the reverse pattern of first increasing the pressure and then reducing the pressure.

The present invention can be used in a leak inspection method and device for electronic components.

1 Quartz crystal resonator 10 Quartz crystal blank 11a, 11b Excitation electrode 13 Conductive adhesive 14 Tray 20 Package 21 Base 211 Bottom 211a, 211b External electrode 211c, 211d Internal electrode 212 Wall 22 Lid 23 Bonding member 300 Leak inspection device 301 Stage 302 Contact probe 302a, 302b Contact pin 303 Contact block 304 Measurement unit 305 Pressure reduction means 306 Pressurization means 307 Control unit 308 Packing 309 Impedance change amount calculation unit 310 Time change amount calculation unit 311 Pressure gradient ratio calculation unit 312 Leak amount calculation unit 400 Inspection chamber 400a Pressure meter 500 Vacuum sealing device 501 Extraction chamber 502 Vacuum chamber 503 Leak inspection device 503a Leak inspection unit 503b Storage unit 504 Transport tray 505 Heating and pressurizing device 506 Cooling device 507 Inspection tray 508 Work holder

Claims (9)

A leak inspection method for calculating a leak amount of an electronic component in which a piezoelectric element is sealed, comprising the steps of:
an impedance change acquisition step of placing the electronic component in an atmosphere having a pressure lower than the internal pressure of the electronic component for a first predetermined time, acquiring a first impedance change of the piezoelectric element, and placing the electronic component in an atmosphere having a pressure higher than the internal pressure of the electronic component for a second predetermined time, acquiring a second impedance change of the piezoelectric element;
and a leakage amount calculation step of calculating an amount of leakage of gas leaking from the electronic component based on a change in the first impedance and a change in the second impedance.
Leak testing methods. the change in the first impedance is a first gradient that indicates the change in the first impedance by a gradient;
the change in the second impedance is a second gradient that indicates the change in the second impedance by a gradient;
calculating a leakage amount of the electronic component from the first gradient and the second gradient;
The leak inspection method according to claim 1 . determining a relationship between time per unit time of the first predetermined time and a change in impedance, or determining a relationship between time per unit time of the second predetermined time and a change in impedance, and calculating an amount of leakage current of the electronic component from the determined relationship;
The leak inspection method according to claim 1 . The impedance change acquisition step includes:
an impedance change amount calculation step of forming a decompression curve formed from the relationship between the change in the first impedance and time and a pressurization curve formed from the relationship between the change in the second impedance and time, and determining an impedance change amount (ΔZ) based on changes in impedance values ( _Zx , _Zs , _Zx > _Zs ) at two different points on the decompression curve or based on changes in impedance values at two points that are the same as the impedance values at the two points on the pressurization curve;
a time change calculation step of calculating a first time change (Δt _d ) based on the times corresponding to the impedance values at the two points on the depressurization curve, and calculating a second time change (Δt _u ) based on the times corresponding to the impedance values at the two points on the pressurization curve;
a pressure gradient ratio calculation step of calculating a pressure gradient ratio ( _γ ) which is a ratio between a decompression pressure gradient indicating a gradient of the decompression curve and a pressurization pressure gradient indicating a gradient of the pressurization curve, from the impedance change amount (ΔZ), the first time change amount (Δt _d ), and the second time change amount (Δt u );
The leakage amount calculation step includes:
an internal pressure ( _Ps ) of the electronic component is calculated from the pressure gradient ratio (γ), and a leakage amount (Q) of the gas leaking from the electronic component is calculated from the internal pressure ( _Ps ) and the elapsed time;
The leak inspection method according to claim 1 . In the pressure reduction curve, the impedance value changes from _Zx to _Zs , which are the impedance values of the two points, and the time changes from a first time corresponding to _Zx to a second time corresponding to _Zs ;
In the pressurization curve, the impedance value changes from _Zs to _Zx , which are the impedance values of the two points, and the time changes from a third time corresponding to Zs to a fourth time corresponding to Zx;
The second time and the third time are the same time.
The leak inspection method according to claim 4. The pressure gradient ratio (γ) is
Calculated by γ=(ΔZ/Δt _d )/(ΔZ/Δt _u ),
(ΔZ is the impedance change amount, Δt _d is the first time change amount, and Δt _u is the second time change amount)
The internal pressure ( _Ps ) is
_Ps is calculated by ( _γPh + _Pl )/(γ+1),
(P _h is the pressure value when pressurized, and P _l is the pressure value when depressurized)
The leakage amount (Q) is
Q is calculated by Q=-VΔP·P _atm /(P _s -P _l )Δt or Q=VΔP·P _atm /(P _h -P _s )Δt.
(V is the internal volume of the piezoelectric element, P _atm is the atmospheric pressure, and Δt is the elapsed time.)
The leak inspection method according to claim 4 or 5. A leak inspection device that calculates the amount of leakage from an electronic component in which a piezoelectric element is sealed, comprising:
a pressure reducing means for reducing the pressure of a first testing space in which the electronic component is placed;
a pressurizing means for pressurizing a second testing space in which the electronic component is placed;
an impedance change acquisition unit that measures the impedance of the piezoelectric element of the electronic component placed in the first and second testing spaces to acquire a change in impedance, the impedance change acquisition unit measuring the impedance of the piezoelectric element to acquire a first change in impedance after placing the electronic component in the first testing space depressurized by the depressurizing means for a first predetermined time, and measuring the impedance of the piezoelectric element to acquire a second change in impedance after placing the electronic component in the second testing space pressurized by the pressurizing means for a second predetermined time;
a leakage amount calculation unit that calculates a leakage amount of gas leaking from the electronic component from the change in the first impedance and the change in the second impedance acquired by the impedance change acquisition unit.
Leak testing equipment. The impedance change acquisition unit is
an impedance change amount calculation unit that forms a decompression curve formed from the relationship between the change in the first impedance and time and a pressurization curve formed from the relationship between the change in the second impedance and time, and determines an impedance change amount based on changes in impedance values at two different points on the decompression curve or based on changes in impedance values at two points that are the same as the impedance values at the two points on the pressurization curve;
a time change amount calculation unit that calculates a first time change amount based on the times corresponding to the impedance values at the two points on the depressurization curve, and calculates a second time change amount based on the times corresponding to the impedance values at the two points on the pressurization curve;
a pressure gradient ratio calculation unit that calculates a pressure gradient ratio, which is a ratio between a decompression pressure gradient indicating a gradient of the decompression curve and a pressurization pressure gradient indicating a gradient of the pressurization curve, from the impedance change amount, the first time change amount, and the second time change amount,
The leak amount calculation unit is
determining an internal pressure of the electronic component from the pressure gradient ratio, and determining an amount of gas leaking from the electronic component from the internal pressure and an elapsed time;
The leak inspection device according to claim 7. The first testing space and the second testing space are the same testing space, the testing space is formed in the same testing room, and the decompression means and the pressurization means are connected to the testing room.
The leak inspection method according to claim 7 or 8.

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