JP2004245752A - Method and apparatus for sealing test - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a method and apparatus for sealing test, with high detection capability for air bubbles, by accurately evaluating sealing performance over a wide range, for dimension of a sample and sizes of leakage holes. <P>SOLUTION: A sample W is placed in air phase 3 within a pressure vessel 1 in which a test liquid F is stared, and a piston 2 is actuated to pressurize the air phase 3 inside the pressure vessel 1 up to a prescribed positive pressure. The sample W is immersed in the test liquid F, while the air phase 3 is pressurized, and then a purge port 22 is opened for and is returned to normal pressure. Then the piston 2 is actuated to depressurize the air phase 3 to a prescribed negative pressure. Sealing performance of the sample W is evaluated, based on the presence of air bubbles generated from the sample W in the test liquid F under depressurized conditions. <P>COPYRIGHT: (C)2004,JPO&NCIPI

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a sealing test method and a sealing test apparatus for evaluating the sealing performance of a sample such as a small-volume electronic component by a bubble-type gross leak test.
[0002]
[Prior art]
As shown in FIG. 1A, a package structure of an electronic component accommodates an element E at the bottom of a concave case C and an opening of the case C. Is closed with a lid L, or as shown in (b), an element E is mounted on a substrate B, and a cover R is placed on the element E.
[0003]
In order to evaluate the sealing performance of such electronic component packages, a bubble-type gross leak test is widely performed. In a general gross leak test, an electronic component is immersed in a test liquid such as fluorocarbon (fluorinated inert liquid) kept at a high temperature, the air inside the electronic component is expanded, and bubbles generated from the electronic component are visually observed. By observing, the quality of the sealing property is determined. In this method, since the electronic components are heated, there is a possibility that the performance and quality of the electronic components may be deteriorated.In addition, the loss of the test solution due to evaporation is large, and it takes time to raise the temperature of the test solution. is there.
[0004]
Patent Document 1 discloses a method in which an electrolytic capacitor is immersed in a liquid in a pressure vessel, the inside of the pressure vessel is evacuated to a negative pressure, and bubbles are observed in a negative pressure state. In this case, by inspecting the sealing performance of the electrolytic capacitor under a negative pressure, a good product and a defective product can be clearly distinguished, and the inspection accuracy can be improved. In addition, there is no need to immerse the sample in a high-temperature test solution, and the above problem can be solved.
[0005]
[Problems to be solved by the invention]
In recent years, the size of electronic component packages has been reduced, and small electronic components having a side of about 1 to 2 mm have been put to practical use. In such a small electronic component, since the inner volume of the package is very small, air bubbles are not easily generated from the electronic component by merely setting the inside of the pressure vessel to a negative pressure state as in Patent Document 1, and the sealing property is reduced. The inspection was difficult.
In addition, not only the size of the electronic component but also the size of the leak hole, the bubble was not separated from the leak portion in both the small leak hole and the large leak hole, and the evaluation was difficult.
[0006]
FIG. 2 shows the relationship between the size of bubbles and the size of leak holes in a sample.
FIG. 2A shows a case where the leak hole is small. Since the pressure at which the test liquid penetrates into the leak hole due to the capillary phenomenon is stronger than the gas expansion pressure from the inside of the sample, air bubbles come out of the leak hole. Can not detect bubbles.
FIG. 2B shows a case in which the leak hole has an appropriate size. When bubbles expand outside the leak hole due to gas expansion, the buoyancy acts more strongly than the adhesive force. Bubbles are released. That is, bubbles can be detected.
FIG. 2 (c) shows an example in which the leak hole becomes large and the adhesive force acting around the leak hole becomes strong, but the bubbles do not expand until the buoyancy enough to separate is obtained. In this case, the air bubbles cannot be separated from the leak hole, and the air bubbles cannot be detected.
If the bubble does not have a sufficient inflation pressure as described above, the leak hole cannot be removed even if the leak hole is too small or too large, and the bubble cannot be detected.
[0007]
Therefore, an object of the present invention is to provide a sealing test method and a device capable of accurately evaluating the sealing property over a wide range with respect to the size of the sample and the size of the leak hole and having a high degree of detection of bubbles. .
[0008]
[Means for Solving the Problems]
In order to achieve the above object, the invention according to claim 1 includes a step of arranging a sample in an air phase in a pressure vessel storing a test liquid, and pressurizing the air phase in the pressure vessel to a predetermined positive pressure. A step of immersing the sample in a test liquid while the air phase is pressurized, a step of reducing the air phase to a predetermined negative pressure, and bubbles generated from the sample in the test liquid in a reduced pressure state And a step of evaluating the sealing performance of the sample depending on the presence or absence of the sealing test method.
[0009]
According to a fourth aspect of the present invention, in a state in which a test solution is stored and a pressure vessel having an air phase above the test solution, and the sample is arranged in the air phase in the pressure vessel, the air phase is subjected to a predetermined positive pressure. Pressurizing means for pressurizing the air phase, a moving mechanism for immersing the sample in the test liquid while the air phase is pressurized, and depressurizing the air phase to a predetermined negative pressure while the sample is immersed in the test liquid. A sealing test apparatus, comprising: a decompression means for performing pressure reduction; and capable of observing bubbles generated from a sample in a test solution in a decompressed state.
[0010]
In the invention according to claim 1, a sample is placed in an air phase in a pressure vessel, and the air pressure of the air phase is increased to a predetermined positive pressure. Therefore, if a leak portion exists in the sample, gas enters the sample package through the leak portion, and the internal pressure increases. Next, the sample is immersed in the test solution while the air phase is pressurized. That is, the sample is immersed in the liquid with the internal pressure increased. Here, when the pressure of the air phase is reduced to a predetermined negative pressure, the pressure applied to the surface of the test liquid decreases, so that the pressure applied to the surface of the sample also decreases. Therefore, if a leak portion exists in the sample, air bubbles are generated from the leak portion due to a difference between the increased internal pressure and the reduced liquid pressure, and the sealing property can be evaluated by observing the air bubbles.
As described above, according to the present invention, after the internal pressure of the sample is increased, the pressure is reduced in the liquid immersion state, so that even in the case of a small sample or a small leak, bubbles generated from the leak portion can be expanded and released. In addition, the sealing property can be accurately evaluated.
[0011]
For example, after a sample is pressurized by a pressurizing device and its internal pressure is increased, the sample is transferred from the pressurizing device to a pressure vessel, immersed in a test solution in the pressure vessel, and the pressure vessel is brought into a negative pressure state. Thus, a method of increasing the degree of detection of bubbles from the sample can be considered. However, in this method, it is necessary to remove the sample from the pressurizing device and transfer it to a pressure vessel.During this time, the sample is exposed to normal pressure and the internal pressure decreases, and the degree of detection of bubbles decreases. Would.
On the other hand, in the present invention, pressurization and depressurization are continuously performed in the same pressure vessel, and the sample is exposed to normal pressure to reduce the internal pressure because the sample is immersed in the test solution in a pressurized state. I can't. Therefore, the degree of detection of bubbles can be increased.
In the present invention, it is not necessary to immerse the sample in a high-temperature test solution as in the conventional gross leak test. Can be solved.
[0012]
As in the second aspect, the step of pressurizing the air phase may be performed by compressing the volume in the pressure vessel.
In general, when pressurizing the air phase of a pressure vessel, it is common to feed compressed air from a high-pressure source such as a pressurizing pump and pressurize it. However, a driving device for driving the pressurizing pump is required. In addition, it is difficult to pressurize the device in a short time as the size of the device increases.
On the other hand, if the air phase is pressurized by compressing the volume in the pressure vessel, the pressurization step can be easily performed to a desired pressure in a short time.
As a specific method of compressing the volume in the pressure vessel, for example, a piston that slides in the pressure vessel is provided, and pressurization can be performed by moving the piston in the compression direction.
[0013]
The step of depressurizing the air phase may be performed by expanding the volume in the pressure vessel.
In order to depressurize the air phase of the pressure vessel, it is common to evacuate and depressurize from a vacuum source such as a vacuum pump.However, a driving device for driving the vacuum pump is required, and the device is large. And it is difficult to reduce the pressure in a short time. On the other hand, if the pressure is reduced by expanding the volume in the pressure vessel, the pressure can be easily reduced to a desired pressure in a short time.
Also in this case, the pressure can be reduced by providing a piston that slides in the pressure vessel and moving the piston in the expansion direction.
[0014]
If the sealing test apparatus according to claim 4 is used, the sealing test method according to claim 1 can be easily implemented.
The moving mechanism preferably has a stage on which the sample is placed, and moves the stage up and down between the air phase and the test solution.
Further, it is preferable to provide a transparent window on the side wall of the pressure vessel, particularly on a portion where the test solution is stored, so that the window can be observed from the outside.
[0015]
According to a seventh aspect of the present invention, there is provided a step of assembling an electronic component having an internal volume of 10 ⁻¹⁰ m ³ or less, and performing the sealing test method according to any one of the first to third aspects using the electronic component as a sample. And a method for manufacturing an electronic component.
In the case of a small electronic component having an inner volume of 10 ⁻¹⁰ m ³ or less, air bubbles are hardly generated from the electronic component simply by setting the inside of the pressure vessel to a negative pressure state as in Patent Document 1, and the sealing property is inspected. However, if the sealing test method according to the present invention is used, the sealing property can be accurately determined even for such a small electronic component, and an electronic component having a good sealing property can be manufactured.
[0016]
The invention according to claim 8 is an electronic component having an internal volume of 10 ⁻¹⁰ m ³ or less, wherein the sealing test method according to any one of claims 1 to 3 is performed using the electronic component as a sample. An electronic component is provided.
Also in this case, similarly to the seventh aspect, by using the sealing test method according to the present invention, it is possible to obtain a small electronic component having good sealing properties.
[0017]
BEST MODE FOR CARRYING OUT THE INVENTION
FIG. 3 shows a first embodiment of the sealing test apparatus according to the present invention, and an electronic component as shown in FIG.
This sealing test device is for performing a bubble-type gross leak test, and includes a pressure vessel 1 having pressure resistance and airtightness. A vertically movable piston 2 is arranged in the pressure vessel 1, and a predetermined amount of test liquid F is stored in a space below the piston 2. As the test liquid F, for example, a liquid having a small surface tension such as a fluorocarbon or an alcohol liquid is used. An air phase 3 is provided above the test liquid F. On the side wall of the pressure vessel 1, a transparent monitor window 4 for observing bubbles B generated from the sample W immersed in the test liquid F is provided.
[0018]
An opening 5 is formed in the upper part of the pressure vessel 1, and the opening 5 is closed by a pressure vessel lid 6. The piston 2 is provided with a sample insertion hole 7 penetrating vertically, and the injection hole 7 is closed by a piston lid 8.
A first screw hole 9 is formed in the upper wall of the pressure vessel 1, and a first ball screw 10 is screwed into the screw hole 9. The upper end of the ball screw 10 is connected to a first motor 12 fixed on the upper surface of the support plate 11. A plurality of columns 13 extending downward are fixed to the support plate 11, and the columns 13 slidably penetrate the pressure vessel lid 6, the piston lid 8, and the piston 2 and extend to the air phase 3. Here, as shown in FIG. 4, four columns 13 are arranged around the sample introduction hole 7, and the space between the column 13 and the piston 2 is hermetically sealed. A stage 14 is fixed to the lower end of the column 13, and the sample W is mounted on the stage 14.
A screw hole 2a and a screw insertion hole 8a are formed on the upper surface of the piston 2 and the flange portion of the piston lid 8, respectively, and a screw 15 is screwed into the screw hole 2a via the screw insertion hole 8a, thereby making the piston The lid 8 is fixed to the piston 2 and the sample insertion hole 7 is closed. The method of fixing the piston 2 and the piston lid 8 is not limited to the method using the screw 15.
[0019]
A guide shaft 16 is provided upright on the upper surface of the pressure vessel 1, and a second ball screw 17 parallel to the guide shaft 16 is screwed through a second screw hole 18 provided in the upper wall of the pressure vessel 1. It is rotatably connected to the piston 2. A second motor 19 is connected to an upper end of the second ball screw 17, and the motor 19 is fixed on a support plate 20 slidable with respect to the guide shaft 16.
A pressure gauge 21 is connected to an upper side wall of the pressure vessel 1, particularly, a side wall corresponding to the air phase 3, and a purge port 22 is provided. The purge port 22 is provided with an on-off valve 23.
The data of the pressure gauge 21 is sent to a controller 24, which controls the first motor 12, the second motor 19, and the on-off valve 23.
[0020]
Next, the operation of the sealing test apparatus having the above configuration will be described with reference to FIGS.
First, before starting the gross leak test, the pressure in the pressure vessel 1 is reduced, and the gas dissolved in the test liquid F is degassed. When the test liquid F is fluorocarbon, the test is performed until the generation of air bubbles disappears. However, the test is preferably performed at 500 Pa or less for 20 minutes or more.
Next, after the sample W is placed on the stage 14 as shown in FIG. 5A, the sample insertion hole 7 is closed by the piston lid 8 and the opening 5 is closed by the pressure vessel lid 6. Then, the first motor 12 is driven to stop the stage 14 immediately above the test solution F. At this stage, the pressure of the air phase 3 is normal pressure, and the on-off valve 23 of the purge port 22 is closed.
Next, as shown in FIG. 5B, the second motor 19 is driven to lower the piston 2 and compress the air phase 3. At this stage, the stage 14 on which the sample W is placed is in the air phase 3, and the internal pressure of the sample W increases. The air pressure of the air phase 3 is measured by the pressure gauge 21.
Next, while the air phase 3 is compressed as shown in FIG. 5C, the first motor 12 is driven to lower the stage 14, and the sample W is immersed in the test liquid F. That is, the sample W is immersed in the test liquid F with the internal pressure increased. At this time, whether or not bubbles are generated from the sample W through the monitor window 4 is observed.
Next, as shown in FIG. 6A, the on-off valve 23 of the purge port 22 is opened to return the air phase 3 to normal pressure. However, since the sample W whose internal pressure has increased is immersed in the test solution F, there is no change in the internal pressure of the sample W. Also at this time, the generation of bubbles from the sample W is observed.
Finally, as shown in FIG. 6B, the purge port 22 is closed, the second motor 19 is driven to raise the piston 2, and the air phase 3 is expanded. Therefore, the pressure of the air phase 3 is reduced. At this stage, since the internal pressure of the sample W is still high and the pressure applied to the test solution F is reduced, if there is a leak in the sample W, the bubbles B expand and easily escape from the sample W. break away. Therefore, by observing the bubble B from the monitor window 4, the sealing property of the sample W can be easily evaluated.
[0021]
An experiment was performed using the test apparatus under the following conditions.
Sample pressurization pressure: 2 × 10 ⁵ Pa (2 atm) or more Sample pressurization time: 10 sec or more Purge time: about 1 sec
Gross leak test pressure: 10 ³ Pa (0.01 atm) or less Gross leak test temperature: 50 ° C. or less Sample W has a structure shown in FIG. 1A or FIG. When a small electronic component having a size of 0.6 × 0.7 mm and an internal volume of 2.52 × 10 ⁻¹¹ m ³ was used, the standard equivalent leak rate was 7.3 × 10 ⁻⁸ Pa · m ^{3 / s to} 2.9. A leak in the range of × 10 ⁻¹ Pa · m ³ / s was detected.
That is, according to the present invention, it is possible to detect a small component, a small leak or a large leak that could not detect bubbles by the method of Patent Document 1 according to the present invention.
Of course, the test conditions vary depending on the size of the standard equivalent leak rate to be detected and the size of the internal volume of the sample.
[0022]
FIG. 7 shows a conventional example using an electronic component having a small internal volume (internal volume: 2.52 × 10 ⁻¹¹ m ³ ) and an electronic component having a large internal volume (internal volume: 4.62 × 10 ⁻¹⁰ m ³ ). FIG. 4 shows the relationship between the gross leak test pressure and the leak rate in the method (Patent Document 1) and the method of the present invention.
Here, the standard equivalent leak rate means that 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, the ambient temperature is 25 ° C. It is defined by the amount of air (Pa · m ³ ). Note that both the conventional method and the present invention were carried out under the same conditions as described above (provided that the pressure was 4 atm).
As is clear from FIG. 7, in the case of the conventional method, air bubbles can be confirmed at around normal pressure if the electronic component has a large internal volume, but if the electronic component has a small internal volume, 70 kPa (0.7 atm.) ) Bubbles cannot be confirmed unless the pressure is reduced below.
Further, also affected by the magnitude of the leak, the internal volume is small parts, only the range of ^{1.11 × 10 -7 Pa · m 3} /s~6.26×10 -2 Pa · m 3 / s bubble Cannot be generated, and it is difficult to evaluate a leak smaller or larger than this.
On the other hand, in the method of the present invention, bubbles can be confirmed even at normal pressure regardless of the size of the internal volume. Moreover, in the part internal volume is small, it is possible to generate bubbles within the ^{9.58 × 10 -10 Pa · m 3} /s~7.34×10 -2 Pa · m 3 / s. That is, bubbles could be generated in a wider range of leak sizes than in the conventional example.
[0023]
FIG. 8 shows a second embodiment of the sealing test apparatus according to the present invention. The same parts as those in the first embodiment are denoted by the same reference numerals, and redundant description will be omitted.
In this embodiment, an air pressure source 30 and a vacuum source 32 are connected to the pressure vessel 1 instead of the piston, and on-off valves 31 and 33 are provided therebetween. A pressure pump or a compression cylinder can be used as the air pressure source 30, and a vacuum pump can be used as the vacuum source 32. The operation of this test apparatus is the same as in FIGS. 5 and 6, and the description of the operation will be omitted.
In this case, since there is no piston that slides inside the pressure vessel 1, the pressure vessel 1 can be downsized, and the second motor for driving the piston can be omitted, so that the structure can be simplified.
[0024]
In the above embodiment, the motors 12 and 19 and the ball screws 10 and 17 are used as the operation mechanism of the stage 14 and the piston 2, but other operation mechanisms such as a fluid pressure cylinder and a voice coil motor may be used. It is.
The method of observing bubbles from the sample is not limited to visual observation, but may be a method of automatically observing and evaluating bubbles using an imaging camera and an image processing device.
Further, in the first embodiment, the operation of the piston 2, the elevation of the stage 14, the opening and closing of the purge port 22, and the like are automatically controlled by the controller 24. However, these operations may be performed manually. .
[0025]
As shown in FIG. 2, when the leak size is equal to or larger than a certain size, buoyancy is not obtained enough for bubbles to separate from the leak portion, and the bubbles remain in the leak portion. Therefore, a means for applying a slight vibration to the sample W immersed in the test liquid F may be provided in order to promote the separation of the bubbles. For example, the vibrator may be connected to the stage 14 supporting the sample W via vibration transmitting means.
The specific conditions for applying the vibration may be set as follows, for example.
Frequency: 100 to 700 Hz, Power: Peak output 80 mW, Waveform: Sine wave, Holding time: 10 sec
In this case, bubbles can be forcibly released by applying vibration to the sample, and in combination with the bubble generation technology by pressurization and decompression in the present invention, it is possible to measure from a minimum leak size to a maximum leak size, The detection accuracy of the sealing property can be improved.
[0026]
As the pressurizing means and the depressurizing means, the piston 2 and its operating mechanism are used in the first embodiment (see FIG. 3), and the pneumatic source 30 and the vacuum source 32 are used in the second embodiment (FIG. 8). One embodiment may be combined with the means of the second embodiment. For example, the piston 2 and the pneumatic source 30 may be used together as the pressurizing means of the first embodiment, and the piston 2 and the vacuum source 32 may be used together as the depressurizing means.
[0027]
Examples of the sample to which the sealing test method according to the present invention can be applied include, in addition to general electronic components, a BAW (Bulk Acoustic Wave) filter and a MEMS (Micro Electro Mechanical System) module, specifically, a silicon gyro, an optical Switch, millimeter wave radar switch, etc.
All of the above products have an extremely small internal volume of 10 ⁻¹⁰ m ³ or less, and all use Pyrex (registered trademark) glass, so that He gas permeates and background noise increases, This is because minute leaks cannot be sorted out.
[0028]
【The invention's effect】
As is clear from the above description, according to the present invention, after increasing the internal pressure of the sample, the sample is immersed in the liquid while the internal pressure is increased, and the pressure is reduced in the liquid immersion state to generate bubbles. Since the observation is performed, bubbles generated from the sample can be expanded, and the generation of bubbles can be promoted. Therefore, the sealing property can be accurately evaluated over a wide range with respect to the size of the sample and the size of the leak.
In addition, since the pressurization and the decompression can be performed in the same pressure vessel, the internal pressure of the sample does not decrease between the pressurization of the sample and the depressurization. Therefore, the degree of expansion of the bubble can be increased, and the detection accuracy can be improved.
Further, since sufficient detection ability can be obtained at room temperature, it is possible to suppress the evaporation of the test liquid and improve the working efficiency.
[0029]
If the method of the present invention is applied to an electronic component having an internal volume of 10 ⁻¹⁰ m ³ or less as in claims 7 and 8, the sealing performance can be improved even for a small electronic component that has been difficult to determine in the past. An electronic component that can be accurately determined and has good sealing properties can be manufactured.
[Brief description of the drawings]
FIG. 1 is a cross-sectional view of a package structure of two types of general electronic components.
FIG. 2 is a diagram illustrating a mechanism of generation of bubbles from a sample.
FIG. 3 is a structural diagram of a first embodiment of a sealing test apparatus according to the present invention.
FIG. 4 is an enlarged sectional view taken along line AA of FIG. 3;
FIG. 5 is a process chart showing the first half of the sealing test method in the present invention.
FIG. 6 is a process chart showing the latter half of the sealing test method in the present invention.
FIG. 7 is a diagram showing the relationship between the reduced pressure and the standard equivalent leak rate depending on the size of the internal volume.
FIG. 8 is a structural diagram of a second embodiment of the sealing test apparatus according to the present invention.
[Explanation of symbols]
Reference Signs List 1 pressure vessel 2 piston 3 air phase 10 ball screw 12 motor 14 stage 17 ball screw 19 motor 21 pressure gauge 22 purge port W sample (electronic component)
F test liquid

Claims (8)

Arranging the sample in the air phase in the pressure vessel storing the test solution,
Pressurizing the air phase in the pressure vessel to a predetermined positive pressure,
A step of immersing the sample in a test solution while the air phase is pressurized,
Depressurizing the air phase to a predetermined negative pressure,
A step of evaluating the sealing performance of the sample based on the presence or absence of bubbles generated from the sample in the test solution under reduced pressure. The sealing test method according to claim 1, wherein the step of pressurizing the air phase is performed by compressing a volume in the pressure vessel. The sealing test method according to claim 1, wherein the step of reducing the pressure of the air phase is performed by expanding a volume in the pressure vessel. A pressure vessel that stores the test solution and has an air phase above the test solution;
Pressurizing means for pressurizing the air phase to a predetermined positive pressure while the sample is arranged in the air phase in the pressure vessel,
A moving mechanism for immersing the sample in the test solution while the air phase is pressurized,
Decompression means for reducing the air phase to a predetermined negative pressure while the sample is immersed in the test solution,
A sealing test apparatus characterized in that bubbles generated from a sample in a test solution under reduced pressure can be observed. The sealing test apparatus according to claim 4, wherein the pressurizing means is a cylinder that changes a volume in the pressure vessel. The sealing test apparatus according to claim 4, wherein the pressure reducing unit is a cylinder that changes a volume in the pressure vessel. Assembling an electronic component having an internal volume of 10 ⁻¹⁰ m ³ or less;
4. A method of manufacturing an electronic component, comprising: performing the sealing test method according to claim 1 using the electronic component as a sample. An electronic component having an internal volume of 10 ⁻¹⁰ m ³ or less,
4. An electronic component obtained by performing the sealing test method according to claim 1 using the electronic component as a sample.

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