JPH05240729A - Leakage inspection device - Google Patents

Abstract

PURPOSE:To provide a leakage inspection device which prevents contamination of a master leak used in correcting sensitivity and can reduce the workload of a worker in handling the master leak. CONSTITUTION:The leakage from a master leak is measured in order to correct the sensitivity of a leakage inspection device and check the condition of the device, by evacuating a vacuum chamber 1 to a predetermined vacuum pressure by means of vacuum chamber exhaust pumps 12, 13, causing trace gases to leak from a trace gas supply source 7 into the vacuum chamber 1 through the master leak at a constant rate and for a predetermined time, and measuring the trace gas concentration of the vacuum chamber 1 using a gas sensor (mass spectrometer)5. The master leak 2 through which the trace gases are periodically made to leak at a constant rate is provided between the trace gas supply source and the vacuum chamber, so as to prevent contamination of the master leak and enable significant reduction in the workload of a worker in handling the master leak.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION The present invention relates to a radiator, heater,
The present invention relates to a leak inspection device for inspecting a hollow device under test such as a condenser and an evaporator for leaks.

[0002]

2. Description of the Related Art A conventional leak test apparatus for a hollow test object is described. First, the hollow test object is placed in a vacuum chamber, and then the hollow test object is filled with a trace gas. Then, the vacuum chamber is evacuated, and the trace gas concentration in the vacuum chamber is measured by a gas sensor such as a mass spectrometer to check for leakage of the hollow test product.

However, the above-mentioned leak inspection device is
Since the measured value is affected by environmental temperature and other subtle changes in each part of the device, conventionally, the operator interrupts the test of the hollow DUT at regular intervals (for example, every 4 hours), and Instead, put a standard leak product called a master leak that has a leak amount equivalent to the leak standard value of the hollow DUT into the vacuum chamber, measure the leak from this master leak to the vacuum chamber with a gas sensor, and obtain the leak measurement value. Compare (current value) with the previous master leak measurement value (previous value),
According to the comparison result, the sensitivity is calibrated and the quality of the leak inspection device is checked.

The order of measuring the leak amount of the master leak is as follows: the vacuum chamber is opened to the atmosphere, the master leak is inserted into the vacuum chamber, and the master leak is traced into the vacuum chamber. (Pipe for filling gas) to fill the trace gas into the master leak, seal the vacuum chamber, sweep the vacuum chamber to a predetermined vacuum pressure, measure the leak, and open the vacuum chamber to the atmosphere. Then, the master leak is separated from the trace gas sealing tube, and the master leak is taken out from the vacuum chamber.

[0005]

However, in the measurement of the master leak leak amount for the sensitivity calibration of the leak inspection device or the device pass / fail check described above, the master leak is usually taken out from the storage place and inserted into the vacuum chamber. Requires a series of operations to connect to the trace gas sealing tube, fill the trace gas inside the master leak, remove the master leak from the tube after measurement, remove it from the vacuum chamber, and store it again in the storage location. However, the master leak is a precision component that is easily damaged and dislikes dirt, and the handling of it is a heavy burden on the operator.

Further, since the master leak is a component which has a filter but has an extremely small leak hole, if dust or dew condensation is caused near the leak hole through the filter during the operation and storage, the master leak leaks. There was a problem that the amount fluctuated. Although a strong filter can be attached to the master leak to prevent dust from reaching the leak hole, the use of an excessively strong (fine-grained) filter affects the leak amount of the master leak. At the same time, since the progress of the dirt is accelerated, a new problem arises in that frequent filter replacement is required.

The present invention has been made in view of the above problems, and it is an object of the present invention to provide a leak inspection apparatus capable of preventing the master leak used for sensitivity calibration and the like from being contaminated and reducing the burden on the operator in handling the leak. Has a purpose.

[0008]

SUMMARY OF THE INVENTION A leak inspection apparatus according to the present invention comprises a vacuum chamber for accommodating a hollow DUT into which a trace gas having a predetermined pressure is injected, and each of the vacuum chambers is swept up to a predetermined vacuum pressure. In a leak inspection device comprising a vacuum chamber exhaust pump for controlling and a gas sensor for sequentially detecting trace gas in each vacuum chamber, a trace gas supply source and each vacuum chamber are connected through a pipe and a valve, and the trace gas It is characterized in that it is provided with a master leak for periodically leaking the trace gas supplied from the supply source into the vacuum chamber at a predetermined leak flow rate.

[0009]

The master leak leakage amount for the sensitivity calibration and the device quality check of this leak inspection device is measured by sweeping the vacuum chamber to a predetermined vacuum pressure with a vacuum chamber exhaust pump,
This is done by leaking the trace gas from the trace gas supply source to the vacuum chamber by a master leak at a constant flow rate for a predetermined time, and measuring the trace gas concentration in the vacuum chamber with a gas sensor.

The sensitivity calibration and the device quality check are
As in the conventional case, the current value of the measured value can be compared with the previous value or a predetermined reference value manually or by an automatic data processor.

[0011]

As described above, in the leak inspection apparatus of the present invention, the master leak for periodically leaking the trace gas at a constant flow rate is provided between the trace gas supply source and the vacuum chamber through the pipe and the valve. Therefore, it is possible to prevent the contamination of the master leak used for sensitivity calibration and the like, and to significantly reduce the burden on the operator in handling the master leak.

[0012]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the leak inspection apparatus of the present invention will be described with reference to the drawings. 1 shows a partial piping diagram, FIG. 2 shows a plan view of a master leak, and FIG. 3 shows a cross-sectional view of a master leak. As shown in FIG.
1 test chamber section (only No. 1 test chamber section is shown in FIG. 1) A, and a trace gas cylinder for supplying trace gas (here, helium gas) to each test chamber section A through a pressure regulating valve 6 (the present invention) Trace gas supply source 7) and each test chamber A
A master leak exhaust pump 9 and vacuum chamber exhaust pumps 12 and 13 exhausted from the chamber, and a mass spectrometer (gas sensor in the present invention) for measuring the trace gas concentration (leakage amount) in the vacuum chamber 1 in each test chamber section A. 5 and.

Since the test chambers A have the same structure, the number of the test chambers A is the same. 1 The configuration of the test chamber section will be described. The vacuum chamber 1 is composed of a metal can body having an opening at one end and a door that opens and closes the opening of the metal can body. By closing the door, the vacuum chamber 1 is made airtight from the outside. A tip end portion of a trace gas sealing tube 16 projects from the ceiling of the vacuum chamber 1, and the trace gas sealing tube 16 is connected to an outlet of the pressure adjusting valve 6 through a trace gas sealing valve 15. Further, the vacuum chamber 1 is connected to vacuum chamber exhaust pumps 12 and 13 which are connected in cascade through a vacuum chamber exhaust valve 10, and the vacuum chamber 1 is connected to a mass spectrometer 5 through a test valve 11.

The trace gas cylinder 7 is filled with high-pressure helium gas, and this high-pressure helium gas is decompressed by the pressure adjusting valve 6 and sent to each valve 15. The mass spectrometer 5 is a gas sensor that selectively detects helium,
The introduced gas to be measured is ionized to be electrostatically accelerated, and the magnetic field is deflected to collect specific ions on the electrode according to the degree of deflection due to the mass difference of the component gases. Since this is well known, detailed description thereof will be omitted.

The characteristic part of the present invention will be described below. The pressure adjusting valve 6 is connected to the suction port of the master leak 2 through the trace gas supply valve 4, and the leak port of the master leak 2 is connected to the ceiling of the vacuum chamber 1 through the calibration valve 3. The master leak 2 is connected to a master leak exhaust pump 9 through a trace gas sweep valve 8.

Details of the master leak 2 will be described with reference to FIGS. Master leak 2 is external housing 20
And an outer housing 20 having an inner housing 30.
The bottom plate 23, the hole plate 24, the middle plate 25, the hole plate 26, and the top plate 27 are sequentially stacked and fastened with long bolts 28. The inner space S1 of the hole plate 24 vertically divided by the bottom plate 23 and the middle plate 25 is an upstream space of the master leak, and similarly the inner space of the hole plate 26 vertically divided by the middle plate 25 and the top plate 27. S2 is a space on the downstream side of the master leak. A lower end portion of a circular can-shaped case 28 having a lower end opening is fitted into and welded to a circular hole penetrating the top plate 27, and the inside of the circular can-shaped case 28 communicates with the internal space S2 by the circular hole.

A through hole is also vertically formed in the central portion of the intermediate plate 25, and an inner housing 30 is erected in the through hole. The inner housing 30 is formed by sequentially stacking a filter holding cylinder 31, a filter 32, a lower cylinder 33, a leak portion 34, an upper cylinder 35, a filter 36, and a filter holding cylinder 37. That is, the lower end portion of the lower cylinder 33 is screwed into the through hole of the intermediate plate 25, and the filter 32 is inserted into the lower end opening of the lower cylinder 33, and then the filter holding cylinder 31 is screwed. .. After the leak portion 34 is placed on the upper end of the lower cylinder 33, the lower end portion of the upper cylinder 35 is screwed onto the upper end portion of the lower cylinder 33, and the leak portion 34 is sandwiched between the lower cylinder 33 and the upper cylinder 35. .. After the filter 36 is inserted into the upper end opening of the upper cylinder 35, the filter holding cylinder 37 is screwed.

The leak portion 34 is sandwiched between the lower cylinder 33 and the upper cylinder 35 and has a base 34a having a central hole (not shown) vertically penetrating in the center thereof, and a tapered portion extending downward from the central portion of the base 34a. The glass tube 34b and the upper end of the glass tube 34b are hermetically sealed to the base 34a. Further, as shown in FIG. 2, the internal space S1 is connected to the outlets of the valves 4 and 5 by piping, and the internal space S2 is connected to the outlet of the valve 3 by piping. Minute holes (not shown) at the lower end of the glass tube 34b determine the leak amount of the master leak 2.

In this master leak, from the trace gas cylinder 7, the valve 4, the internal space S1, the filter 32,
Glass tube 34b, filter 36, internal space S2,
The trace gas leaks to the vacuum chamber 1 through the valve 3 at a constant flow rate. When the master leak exhaust pump 9 is operated with the valves 3 and 4 closed and the valve 5 opened, the trace gas inside the master leak 2 is exhausted to the outside by the exhaust pump 9.

The procedure of the leak test of the hollow DUT by the leak inspection apparatus will be described below. The vacuum chamber exhaust pumps 12 and 13 and the master leak exhaust pump 9 are assumed to be constantly operating. First, the hollow DUT 14 is placed in the vacuum chamber 1, and the gas injection portion (not shown) of the hollow DUT 14 is connected to the trace gas sealing tube 16. Next, the door of the vacuum chamber 1 is closed, the valve 10 is opened, and the inside of the vacuum chamber 1 is evacuated. Further, the valve 15 is opened and the trace gas is enclosed in the hollow DUT 14. Depending on the hollow DUT 14, the trace gas may be charged into the vacuum chamber 1 after being filled therein.

As a result, if there is a leak in the hollow DUT 14, the trace gas leaks into the vacuum chamber 1. Therefore, when the valve 11 is opened, the trace gas is introduced into the mass spectrometer 5, and the mass spectrometer 5 The leak amount is measured by integrating the detected ion current for a predetermined time. The valve 11 is designed to open only for the time required for measurement. Since the measurement sensitivity of such a leak inspection device varies due to subtle changes in the mass spectrometer 5 and the vacuum system, the master leak leakage amount described below is measured, and the performance of the device is confirmed based on this measurement result. And sensitivity calibration are performed every 4 hours.

The measurement of the master leak leakage amount will be described below. The valves 3, 4, 10, 11, 15 are closed and the valve 8 is opened before the measurement of the master leak leakage amount. First, the measured hollow device under test 14 is taken out of the vacuum chamber 1 and the door is closed. Then, the valve 10 is opened, the vacuum chamber 1 is evacuated to the reference pressure, and the valve 10 is closed. Open and close valve 8,
Trace gas is introduced from the cylinder 7 through the master leak 2 into the vacuum chamber 1 at a standard timing and a constant leak amount. Then, the valve 11 is opened and the amount of trace gas leakage is measured by the mass spectrometer 5.

After this measurement, the valves 3, 4, 10, 11,
15 is closed, the valve 8 is opened, the atmosphere is introduced into the vacuum chamber 1 by a valve (not shown), the door is opened, and the next hollow DUT 14 is received. The master leak leak amount output from the mass spectrometer 5 is checked by a data processing device (not shown) to see if it is within a certain allowable range. If it is within that range, this data processing device is considered to be in good operation. It judges and permits the subsequent measurement. If it is out of the range, an alarm is issued and the subsequent measurement is interrupted. Further, the data processing device compares the previous value (measured 4 hours before) with the current value of the master leak leakage amount, and multiplies the ratio by the future measured value to perform sensitivity calibration.

From the above, the No. 1 Test chamber part A
Although the measurement of the master leak leakage amount and the sensitivity calibration of the above have been described, the above operation is performed for the other five test chamber parts A.
Also do in order. Since the above-mentioned work for one test chamber A can be sufficiently performed in the same time range (for example, 20 seconds) as the work for measuring the leak amount for a normal hollow DUT, 20 × for all test chambers A after all.
The work of measuring the master leak leakage amount can be completed in 6 = 120 seconds.

In the embodiment described above, the master leak 2
Although a component having a minute leak hole is used as the above, a constant leak amount can be obtained by gas permeation of the glass wall and the like, and even in this case, the master leak 2 can be prevented from being soiled. As described above, the leak inspection device
Since the master leak 2 that periodically leaks the trace gas at a constant flow rate is provided between the cylinder 7 and the vacuum chamber 1 so as to be openable and closable, the master leak 2 can be prevented from being contaminated, and the master leak 2 can be prevented. Since the handling is unnecessary, the burden on the operator can be reduced.

That is, both ends of the master leak of the present invention are connected between the trace gas supply source and the vacuum chamber through pipes and valves, stored outside the vacuum chamber as in the conventional case, and manually put in and taken out from the vacuum chamber. It is much less likely to be polluted than when it is used. The only source of pollution is dust and moisture in the air that flows into the vacuum chamber from the outside when the door of the vacuum chamber is opened, but the air that has flowed into the vacuum chamber is immediately closed by the vacuum chamber exhaust pump after the door is closed. As it is evacuated, these dust and water that accompany the vacuum chamber are discharged to the outside by this exhaust gas stream and immediately evaporated, and the vacuum chamber is clean most of the time. Furthermore, the operator does not need to handle the master leak when measuring the leak amount of the master leak, so that the burden can be reduced, and a space for storing the master leak is not required, so that space can be saved.

Other effects of this embodiment will be described below. (1) First, in this embodiment, the master leak 2 and the vacuum chamber 1
Are connected through the valve 3, and the valve 3 is opened only when measuring the master leak leakage amount. By doing this, it is possible to prevent the dirty air from the vacuum chamber 1 from entering the master leak 2 while the vacuum chamber 1 is open to the atmosphere.
It is possible to prevent clogging of the master leak 2 and damage to the filter.

(2) Next, in this embodiment, the master leak 2 and the vacuum chamber 1 are connected through the valve 3, the master leak 2 and the cylinder 7 are connected through the valve 4, and the master leak 2 and the master leak exhaust are further connected. After the measurement of the master leak leakage amount is completed by connecting the pump 9 to the valve 8, the valves 3 and 4 are closed, the valve 8 is opened, and the remaining traces in the master leak 2 and in the pipe connected to the master leak 2 are traced. Exhausting gas.

With this arrangement, the residual trace gas inside the master leak 2 and in the pipe connected to the master leak 2 is measured as the next leak amount measurement value when the next master leak amount is measured. Can be avoided and the calibration accuracy can be improved. Although the valve 8 is provided upstream of the minute holes of the master leak 2 in the above-described embodiment, it may be provided downstream, or both.

[Brief description of drawings]

FIG. 1 is a block diagram showing an embodiment of a leak inspection device of the present invention,

FIG. 2 is a plan view of the master leak shown in FIG.

3 is a sectional view of the master leak of FIG. 1,

[Explanation of symbols]

1 is a vacuum chamber, 2 is a master leak, 5 is a mass spectrometer (gas sensor), 7 is a trace gas cylinder (trace gas supply source), 14 is a hollow DUT, 12 and 13 are vacuum chamber exhaust pumps,

Claims (1)

[Claims] 1. A vacuum chamber for accommodating a hollow DUT into which a trace gas having a predetermined pressure is injected, a vacuum chamber exhaust pump for sweeping each vacuum chamber to a predetermined vacuum pressure, and each of the vacuum chambers. In a leak inspection apparatus including a gas sensor for sequentially detecting the trace gas, a trace gas supply source and each of the vacuum chambers are connected through a pipe and a valve, and the trace gas supplied from the trace gas supply source is connected to the vacuum chamber. A leak inspection device comprising: a master leak that periodically leaks to a predetermined leak flow rate.