JP2005005350A - Method of sealing and sorting electronic component - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a method by which electronic components can be sorted by certainly evaluating the defectively sealed states of the components even when the components have very small internal volumes. <P>SOLUTION: This method includes a step of reducing the pressure in a pressure-resistant container 1 containing a liquid F after electronic components W are dipped in the liquid of the pressure-resistant container 1 where liquid F is stored, a step of infiltrating the liquid F into defectively sealed electronic components W by returning the pressure in the container 1 to a normal pressure, and a step of taking out the electronic components W from the container 1. The method also includes a step of measuring the electrical characteristics of the components W taken out from the container 1 and sorting the defectively sealed electronic components W based on the measured results of the electrical characteristics. The functions of the defectively sealed electronic components W are deteriorated or broken by infiltrating the liquid F into the electronic components W, and the deteriorated or broken functions are discriminated by measuring the electrical characteristics. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a method for sealing and selecting electronic components suitable for evaluating and selecting the sealing performance of electronic components having a minute internal volume.
[0002]
[Prior art]
[Patent Document 1] Japanese Patent Application Laid-Open No. 7-106393 Conventionally, test methods such as a He leak test, a gross leak (bubble leak) test, and an air leak test have been widely used as methods for selecting the sealing performance of electronic components. .
In the He leak test, the atmospheric partial pressure in the work is reduced by evacuation, and then He gas is filled at a high pressure. Next, the work is once taken out into the atmosphere, put into a test port, the inside of the port is made high vacuum, the He gas in the work is sucked out, and the amount of leaked He is measured by a mass spectrometer.
The gross leak test is a method for determining the presence or absence of a leak by immersing the work in heated fluorocarbon (fluorine-based inert liquid), expanding the gas in the work and observing bubbles generated from the leak. .
The air leak test is a method of determining the presence or absence of a leak by comparing the pressure difference with the master work side where there is no leak. If there is a leak, the applied pressure is divided in the work, so the pressure drops and a pressure difference occurs between the master side. In addition, when the pressure inside the work is saturated simultaneously with the application of pressure, the large leak detection is performed by connecting to the large leak detection tank after applying the pressure. When there is a leak, the volume on the measurement side apparently increases by the work content integral. Therefore, when connected to a large leak detection tank, the pressure on the master side decreases and a differential pressure is generated.
[0003]
[Problems to be solved by the invention]
However, in the conventional test method, it has been difficult to measure the sealing performance of an electronic component having a minute internal volume (for example, the internal volume is 10 ⁻¹⁰ m ³ or less) for the following reasons.
That is, in the He leak test, since the workpiece is once taken out into the atmosphere from the He filling to the start of measurement, the filling He leaks, and during the measurement, the He partial pressure in the workpiece is reduced below the measurement limit. It becomes difficult.
In the gross leak test, bubbles having a large leak size do not release bubbles from the leak portion, and those having a small leak size do not generate bubbles, making evaluation difficult.
In the air leak test, even if there is a leak, the internal volume is small, so that a differential pressure higher than the detection sensitivity of the sensor does not occur and evaluation becomes difficult.
In addition, it is necessary to determine whether the workpiece is good or defective after measuring the leak rate in the He leak test and the differential pressure with the master capsule in the air leak test. It is difficult to test a large number of workpieces at once. Yes, processing efficiency was poor.
Furthermore, the gross leak test is performed with fluorocarbon at a high temperature (about 125 ° C.). This is because the work is heated based on Boyle-Charle's law, and the volume of the internal gas is expanded to facilitate the generation of bubbles. In fact, this method is also described in the MIL standard and the JIS standard, and is widely used as a general method for the gross leak test. However, since the test is performed at a high temperature, there is a risk that the function of the part may be impaired even if the product has a good sealing property in a work with low heat resistance or a work whose part characteristics are changed by applying heat.
[0004]
Patent Document 1 discloses a method that enables more reliable evaluation of sealing performance by performing fine leak sorting after assembly / sealing of a sealed electronic component and then performing gross leak sorting. is suggesting.
However, performing these two sealing tests increases the number of processes and decreases productivity. In addition, in an electronic component having a minute internal volume, it is difficult to evaluate leakage even if two sealing tests are performed, and the above problem cannot be solved.
[0005]
SUMMARY OF THE INVENTION An object of the present invention is to provide a sealing and sorting method for electronic components that can reliably evaluate and sort sealing defects even with electronic components having a minute internal volume.
[0006]
[Means for Solving the Problems]
In order to achieve the above object, according to a first aspect of the present invention, there is provided an electronic component sealing / selecting method in which an interior of a package containing an element is sealed, wherein the electronic component is placed in a liquid in a pressure-resistant container storing the liquid. After the immersion, the inside of the pressure vessel is brought to the first pressure state, or the inside of the pressure vessel is brought to the first pressure state, and then the step of immersing the electronic component in the liquid and the inside of the pressure vessel are taken as the first pressure state. A second pressure state higher than the pressure state, a step of infiltrating the liquid into the poorly sealed electronic component, a step of taking out the electronic component from the pressure vessel, and an electric of the electronic component taken out from the pressure vessel There is provided a method for sealing and selecting an electronic component, which includes a step of measuring a mechanical characteristic and selecting a defect by the electrical measurement.
[0007]
A case where the first pressure state is a reduced pressure state and the second pressure state is a normal pressure state will be described as an example.
For example, when an electronic component is immersed in a liquid in a pressure resistant container under normal pressure and then the pressure inside the pressure resistant container is reduced, air inside the electronic component expands, and bubbles are generated from the leak portion. Next, when the pressure vessel is returned to normal pressure, a large liquid pressure is applied to the electronic component by the difference between the normal pressure and the reduced pressure, so that the liquid penetrates into the electronic component from the leak portion.
Alternatively, the electronic component may be placed in the gas of the pressure vessel under normal pressure, the pressure inside the pressure vessel may be reduced, the electronic component may be immersed in a liquid, and then the pressure vessel may be returned to normal pressure. Also in this case, when the pressure inside the pressure vessel is returned to normal pressure, a large liquid pressure is applied to the electronic component by the difference between the normal pressure and the reduced pressure, so that the liquid penetrates into the electronic component from the leak portion.
In this way, the liquid function is positively permeated into the electronic component from the leak portion, thereby degrading or destroying the electrical function of the defective sealing product. For example, a liquid that has penetrated into a defectively sealed product adheres to an internal circuit or a sensing portion of an electronic component and changes its electrical characteristics. Thereafter, the electronic component is taken out from the pressure vessel, and the electrical characteristics of the electronic component are measured in a characteristic selection step. An electronic component with good sealing performance naturally has no abnormality in electrical characteristics. However, in the case of a defective sealing product, since there is an abnormality in electrical characteristics, it is possible to easily determine sealing defects.
In the present invention, it is only necessary to provide a pressure difference so that the liquid can penetrate into the poorly sealed electronic component. The first pressure state is not limited to the reduced pressure state (negative pressure state), but is normal pressure or positive pressure. There may be. Similarly, the second pressure state is not limited to the normal pressure, and may be a negative pressure or a positive pressure. The second pressure state only needs to be higher than the first pressure state.
[0008]
The discrimination based on the electrical characteristics as described above is different from that used for visual observation of bubbles such as the gross leak test, and even electronic components with minute internal volumes can be clearly and quickly distinguished. Inspection accuracy and efficiency can be improved. Moreover, since the discrimination based on the electrical characteristics can be automatically performed by a known apparatus, the number of production personnel can be reduced and the production cost can be reduced.
Further, in the present invention, it is not necessary to observe bubbles generated from the electronic component in a state where the electronic component is immersed in the liquid, so it is possible to immerse a large number of electronic components in the liquid at a time, and processing efficiency Can be improved.
In the defect selection step, not only defective products but also defective products having electrical characteristics (initial property defective products) can be determined together. Therefore, it is possible to simultaneously select defective sealing products and initial characteristic defective products by performing the defective selection process only once, and it is not necessary to provide a separate process for selecting defective sealing products, thereby reducing the number of processes. .
In the present invention, the pressure vessel is set to a negative pressure in order to allow the liquid to penetrate into the electronic component. Unlike the conventional high-temperature gross leak test, it is not necessary to heat the liquid, so even electronic components with low heat resistance and electronic components whose characteristics change when heated can be selected without impairing the function. In addition, it is possible to solve problems such as liquid loss due to evaporation and the time required to raise the temperature of the liquid.
[0009]
If the first pressure state is a negative pressure state and the second pressure state is a normal pressure state as in claim 2, the liquid that has penetrated into the interior when the electronic component is taken out from the pressure vessel (liquid) Can be prevented, and after the pressure is reduced for the first time, it is only necessary to purge, so that there is an advantage that the work process is simplified.
[0010]
There are various liquids that can be used in the present invention.
As in claim 3, an inert liquid may be used. Since the inert liquid has low polarity, it has a low viscosity and easily enters the electronic component from the leak portion. In particular, a liquid having a low viscosity and a high specific gravity, such as fluorocarbon, can easily enter the electronic component from the leak portion. Since the liquid that has entered inside adheres to the element and changes its electrical characteristics, it is possible to easily determine the sealing failure.
As in claim 4, a liquid having a property of corroding a conductive portion inside the electronic component may be used. An example of such a liquid is an acid. In the case of an electronic component having an internal electrode made of a base metal such as aluminum, if an acid or the like enters the electrode, the electrode is corroded or dissolved, and the electrical function is destroyed, so that a sealing failure can be easily identified.
As in claim 5, a liquid having conductivity such as water may be used. In this case, if the liquid enters the electronic component and adheres between the internal electrodes, the electrical characteristics are changed or lost because the electrodes are short-circuited.
Heating that hardens the liquid between the step of taking out the electronic component from the pressure vessel and the step of measuring the electrical characteristics of the electronic component using a liquid having a property of being cured by heat treatment as in claim 6 A processing step may be provided. An example of such a liquid is a thermosetting resin (such as an epoxy resin). In this case, the liquid that has entered the inside of the electronic component is cured, so that the electrical characteristics of the element (for example, vibration characteristics in the case of a piezoelectric element) change, and a sealing failure can be determined.
[0011]
The present invention is effective when applied to an electronic component having an internal volume of 10 ⁻¹⁰ m ³ or less as in the seventh aspect.
In the case of an electronic component having a minute volume with an internal volume of 10 ⁻¹⁰ m ³ or less, it has been difficult to detect a sealing failure by the conventional test method, but it can be reliably determined by using the method of the present invention. .
[0012]
DETAILED DESCRIPTION OF THE INVENTION
FIG. 1 shows an example of a test apparatus used in the sealing and sorting method according to the present invention.
The electronic component W used for sealing selection includes a package P and an element E accommodated therein, and the inside of the package P is hermetically sealed.
This test apparatus includes a pressure vessel 1 having pressure resistance and airtightness. In the pressure vessel 1, a liquid F such as fluorocarbon is stored. A pressure reducing pump 2 and a pressure gauge 3 for reducing the pressure inside the container 1 are connected to the upper part (air phase) of the pressure resistant container 1. The pressure reduction in the pressure vessel 1 may be performed by arranging a piston in the pressure vessel 1 and expanding the internal volume by the piston. A purge port 4 having a valve 5 is connected to the upper portion of the pressure vessel 1.
[0013]
Next, a method for performing sealing selection using the test apparatus having the above configuration will be described with reference to FIG.
First, before putting the electronic component W into the pressure vessel 1, the pressure reducing pump 2 is operated to reduce the pressure in the vessel 1 (see FIG. 2A). Thereby, the gas dissolved in the liquid F is degassed. As conditions, it is desirable to process at a normal temperature (25-30 degreeC) and a pressure of 200-500 Pa for about 30 minutes. This degassing process is a pre-process for sealing selection, and is performed as necessary.
After the degassing process, the valve 5 is opened to purge the pressure-resistant container 1 from the purge port 4, and the inside of the container 1 is returned to normal pressure. And the sealed electronic component W is immersed in the liquid F, and the pressure-resistant container 1 is sealed (refer (b) of FIG. 2).
Next, the decompression pump 2 is operated to decompress the inside of the container 1 again (see (c) of FIG. 2). As conditions, it is desirable to process for about 5 minutes at room temperature (25-30 degreeC) and the pressure of 1000 Pa or less. Since the pressure in the container 1 is reduced by this decompression process, the pressure applied to the electronic component W in the liquid is reduced, and the gas inside the electronic component W starts to expand based on Boyle-Charles' law. In the case of an electronic component W with poor sealing, the volume expansion of the internal gas is released as bubbles B from the leak portion to the outside of the electronic component W, and the internal pressure of the electronic component W is the pressure around the electronic component where the pressure has decreased. Try to balance.
Next, the valve 5 is opened, the pressure vessel 1 is purged from the purge port 4, and the inside of the vessel 1 is returned to normal pressure (see (d) of FIG. 2). At this time, since the external pressure returns to normal pressure, in the case of the electronic component W with poor sealing, the pressure applied to the surroundings returns to the state before the pressure is reduced. However, since the internal pressure of the electronic component W remains in an equilibrium state when the pressure is reduced, a pressure difference is generated, and the liquid F enters the electronic component W. Thereby, the function of the electronic component W deteriorates or is destroyed. The electronic component W having no sealing failure does not change the internal pressure, so that the liquid F does not enter and the component function is not impaired. In this step, since it is not necessary to observe bubbles generated from the electronic component W, a large number of electronic components W may be immersed in the pressure-resistant container 1 at the same time. Moreover, it is not necessary to heat the liquid F, and what is necessary is just to implement at normal temperature (25-30 degreeC).
The electronic component W for which the above processing has been completed is taken out from the pressure-resistant container 1 and its electrical characteristics are measured by the characteristic measuring device 6 (see FIG. 2E). Examples of the electrical characteristics include a resonance frequency, a band loss, a cutoff frequency, a resistance value, and a capacitance. Here, since the liquid F has entered the electronic component W having a poor sealing due to the above-described processing, desired electrical characteristics cannot be obtained and the defective sealing can be determined. Further, in this sorting step, not only the sealing failure but also the initial characteristic failure (there is no sealing failure but the electrical property is poor) can be selected together.
[0014]
FIG. 3 is a diagram showing the flow of the sealing selection method.
First, pressure reduction (degassing) processing is performed (step S1), and then purge is performed to return the pressure vessel 1 to normal pressure (step S2). Steps S1 and S2 are pre-processes. Next, the electronic component W is put into the pressure vessel 1 and immersed in a liquid (step S3), and the pressure vessel is depressurized (step S4). Next, when purging and returning the pressure vessel 1 to normal pressure (step S5), the liquid enters the electronic component W with poor sealing. Next, the electronic component W is taken out from the pressure-resistant container 1 (step S6), and the electrical characteristics of the electronic component W are measured and selected (step S7).
By performing the above processing, it is possible to reliably select sealing defects even in the electronic component W having a minute internal volume.
In the above sorting method, after the electronic component W is immersed in the liquid in step S3, the pressure vessel 1 is depressurized in step S4. On the contrary, the electronic component W is placed in the air phase of the pressure vessel 1. In this state, the pressure may be reduced, and then the electronic component W may be immersed in the liquid. In this case, since the internal pressure of the poorly sealed electronic component W in the air phase is lowered, the penetration of the liquid when the electronic component W is immersed in the liquid and then returned to normal pressure is promoted.
[0015]
In piezoelectric parts such as piezoelectric oscillators, SAW elements, piezoelectric filters, and precision parts such as semiconductors, even if a small amount of foreign matter (liquid F) enters the package and adheres to the electrodes, the electrical characteristics change greatly. The sealing failure can be easily determined.
As the liquid F, in addition to an inert liquid such as fluorocarbon, a metal corrosive liquid such as an acid, a liquid having conductivity such as water (including salt water), or a heat treatment such as a thermosetting resin. A liquid having properties may be used.
For example, in the case of a SAW element, when the liquid F adheres to the IDT electrode, the propagation frequency changes, so that the abnormality can be easily determined. Since the IDT electrode of the SAW element is formed of an aluminum film, when diluted hydrochloric acid or the like adheres, the IDT electrode dissolves and its function is destroyed. Specifically, dilute hydrochloric acid having a pH of 3 or less is preferable. Furthermore, if water adheres on the IDT electrode, a short circuit occurs between the IDTs and the electrical characteristics are lost.
When using a thermosetting resin (such as thermosetting epoxy), it is preferable to use a resin having a viscosity of 1 Pa · s or less, for example. After reducing the pressure to 100 Pa or less and returning to normal pressure, the electronic component is taken out from the pressure vessel. Thereafter, a resin curing process (curing temperature: 100 ° C., curing time: 180 minutes) is performed, and sorting based on electrical characteristics is performed.
In the case of a thermosetting resin, since it does not volatilize, sealing failure can be reliably detected even if the time until the characteristic selection elapses after the electronic component is taken out from the pressure vessel.
[0016]
FIG. 4 is a diagram showing the relationship between the test solvent (liquid) external pressure and the standard equivalent leak rate when the method of the present invention and the conventional method (gross leak test) are used. Here, an electronic component having an internal volume of 10 ⁻¹⁰ m ³ was used.
The standard equivalent leak rate is the amount of dry air that leaks in one second from the leak point at an ambient temperature of 25 ° C. when the high pressure side is 1 atm (760 mmHg or 1.013 × 10 ⁵ Pa) and the low pressure side is 1 mmHg (133 Pa) or less. It is defined by (Pa · m ³ ). In the conventional gross leak test, the leak rate detection range is 2.95E-7 to 2.95E-5 (Pa · m ³ / s). The sealing failure can be measured.
[0017]
In the above embodiment, an example is shown in which the liquid is infiltrated into the electronic component with poor sealing by returning to the normal pressure after the pressure reducing process. Good. In this case, the infiltration of the liquid is further facilitated, and the detection accuracy is further improved.
Samples to which the sealing and sorting method according to the present invention can be applied include not only general electronic components but also BAW (Bulk Acoustic Wave) filters, MEMS (Micro Electro Mechanical System) modules, specifically silicon gyros, optical There are switches and millimeter wave radar switches.
All of the above products have an extremely small internal volume of 10 ⁻¹⁰ m ³ or less, and all use glass such as Pyrex (registered trademark) glass, soda glass, and quartz glass, so that He gas is transmitted therethrough. This is because background noise increases and minute leaks cannot be selected.
[0018]
【The invention's effect】
As is clear from the above description, according to the present invention, the electronic component is immersed in the liquid in the first pressure state, and the pressure vessel is brought into the second pressure state higher than the first pressure. Since liquid is infiltrated inside the poorly sealed electronic component, the electronic component is taken out of the pressure vessel, its electrical characteristics are measured, and defective selection is performed by the electrical measurement. Unlike the case where a simple bubble is discriminated by visual observation, even an electronic component having a minute internal volume can be discriminated clearly in a short time, and the accuracy and efficiency of sealing inspection can be improved.
Further, in the present invention, since it is not necessary to observe bubbles generated from the electronic component in a state where the electronic component is immersed in the liquid, it is possible to immerse a large number of electronic components in the liquid at a time, and to improve the processing efficiency. Improvements can be realized.
In the defect sorting process, not only defective products but also defective products with initial electrical characteristics (initial property defective products) can be discriminated together, so it is necessary to provide a separate process for selecting defective products. The number of processes can be reduced.
In addition, the pressure in the pressure vessel is changed in order to infiltrate the liquid into the electronic component, and there is no need to heat the liquid as in the conventional high-temperature gross leak test. There is an effect that even an electronic component whose characteristics are changed by heating can be selected without impairing the function.
[Brief description of the drawings]
FIG. 1 is a structural diagram of an example of a test apparatus used in a sealing selection method according to the present invention.
FIG. 2 is a process diagram showing a sealing selection method in the present invention.
FIG. 3 is a flowchart showing a process flow of FIG. 3;
FIG. 4 is a diagram showing a relationship between a test solvent external pressure and a standard equivalent leak rate in an electronic component having a small internal volume.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 Pressure-resistant container 2 Pressure reducing pump 3 Pressure gauge 4 Purge port 6 Characteristic measuring device W Electronic component E Element P Package F Liquid

Claims (7)

In the sealing selection method of the electronic component formed by sealing the inside of the package containing the element,
After immersing the electronic component in the liquid of the pressure vessel storing the liquid, the inside of the pressure vessel is set to the first pressure state, or the pressure vessel is set to the first pressure state, and then the electronic component is placed in the liquid. Dipping in,
A step of setting the inside of the pressure vessel to a second pressure state higher than the first pressure state, and infiltrating the liquid into the electronic component having a poor sealing;
A step of removing the electronic component from the pressure vessel;
Measuring the electrical characteristics of the electronic component taken out from the pressure vessel, and performing defect sorting by the electrical measurement. The first pressure state is a negative pressure state,
2. The electronic component sealing and selecting method according to claim 1, wherein the second pressure state is a normal pressure state. 3. The electronic component sealing / selecting method according to claim 1, wherein the liquid is an inert liquid. 3. The electronic component sealing and selecting method according to claim 1, wherein the liquid is a liquid having a property of corroding a conductive portion inside the electronic component. 3. The electronic component sealing / selecting method according to claim 1, wherein the liquid is a conductive liquid. The liquid is a liquid having a property of being cured by heat treatment,
3. The electronic device according to claim 1, further comprising a heat treatment step of curing the liquid between the step of taking out the electronic component from the pressure-resistant container and the step of measuring electrical characteristics of the electronic component. Sealing and sorting method for parts. The electronic component sealing and sorting method according to any one of claims 1 to 6, wherein the electronic component is an electronic component having an internal volume of 10 ^-10 m ³ or less.

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