JPH09196797A - Leakage inspecting apparatus - Google Patents

Abstract

PROBLEM TO BE SOLVED: To make it possible to accurately inspect leakage in a short cycle time by a reverse diffusion type helium leak detector. SOLUTION: In the leakage inspecting apparatus, a tube 11 communicating with a test port 10 connected to a test chamber 1 and a connecting tube 14 communicating with the exhaust port of a turbo-molecular pump 13 for constituting a reverse diffusion type helium leak detector 12 are connected to an auxiliary exhaust pump 15 such as an oil rotary pump, and the exhaust of the tube 11 and the auxiliary exhaust of the pump 13 are conducted by an auxiliary exhaust pump 15. A drag-molecular pump 17 for exhausting to the pump 15 from the port 10 is disposed at the tube 11.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an apparatus for leak-checking an airtight article used for automobiles, home electric appliances, etc. by using a helium gas with a reverse diffusion helium leak detector.

[0002]

2. Description of the Related Art Conventionally, J.
There is known a two-chamber type apparatus as shown in FIG. 1 by a pressurized vacuum method based on IS-Z2331. This device has two volumes of about 20 to 100 liters for inserting a test body a such as a refrigerator part for testing the airtightness which has been previously pressurized to about 5 kg / cm ² with helium gas. The test chambers b, b, an exhaust pump d such as an oil rotary pump for exhausting the inside of each test chamber b to about several Pa through the exhaust pipes c, c, and each test chamber b
A helium leak detector device f connected to the inside of the leak detector device f is provided, and an opening / closing valve g for rough evacuation is provided in each exhaust pipe c, and an introduction pipe e to the leak detector device f is provided for inspection. Open / close valves h, h for the respective valves are interposed, and the chamber b is provided with open / close valves i, i for venting to open the inside thereof to the atmospheric pressure. As the exhaust pump d, a combination of an oil rotary pump and a mechanical booster pump may be used.

The helium leak detector device f is
Recently, a reverse diffusion type using a turbo molecular pump for its exhaust system has become popular, and as shown in FIG. 2, a mass spectrometer tube j of magnetic field deflection type and a turbo molecule having an intake port connected to exhaust the inside thereof. A reverse diffusion helium leak detector 1 consisting of a pump k and a pipe n communicating with the test port m
And an auxiliary exhaust pump p such as an oil rotary pump or a dry pump is connected to a connecting pipe o connected to the exhaust port of the turbo molecular pump k. The test port m is connected to the introduction pipe e through the on-off valve for inspection shown in FIG.

In the two-chamber type leak inspection apparatus, while a test body a put in one chamber b is leak-checked by a leak detector device f, another test body a is put in the other chamber b. Exhaust pump d in chamber b
Therefore, there is an advantage that rough exhaustion can be performed to prepare for a leak inspection and the inspection time can be shortened. To explain the operation, a test body a whose inside is pressurized with helium gas is placed in one chamber b, an opening / closing valve g for rough evacuation is opened and vacuum exhaust is performed, and when the pressure is reduced to about 1 Pa, Open / close valve g
Is closed and the on-off valve h for inspection is opened to connect to the helium leak detector device f to perform a leak inspection. At the time of entering the leak inspection, rough evacuation of the other chamber b containing another test body a is started. If one of the test bodies a leaks, the leaked helium gas leaked into the chamber b is captured by the leak detector f, and the presence or absence of the leak can be confirmed. Leakage of the test body a in the other chamber b is similarly inspected. Generally, the cycle time of one chamber is set to about 30 seconds, and one chamber can be inspected every 15 seconds by using two chambers.

The helium gas leaked from the test body a is
Although it is sucked from the introduction pipe e in FIG. 1 to the auxiliary exhaust pump p through the test port m in FIG. 2, since helium gas is light and the gas molecules are small, the helium gas diffuses backward from the exhaust port of the turbo molecular pump k to the intake port. Then, it is detected by the mass spectrometer tube j.

[0006]

The cycle time of the above-mentioned general leak inspection apparatus is such a short time that one inspection is carried out in 20 to 30 seconds in one chamber. When a reverse diffusion type helium leak detector is attached to a leak inspection device that operates in a short cycle time, the introduction pipe e between the on-off valve h for inspection and the helium leak detector device f in FIG. Helium gas leaked from the defective test body a remains, for example, the test body a in one chamber b is a defective product, and the other test body is a good product. There was a case to judge.

An object of the present invention is to provide an apparatus capable of performing an accurate leak inspection with a short cycle time using a reverse diffusion type helium leak detector.

[0008]

According to the present invention, a pipe connected to a test port connected to a test chamber and a connection pipe connected to an exhaust port of a turbo-molecular pump constituting a reverse diffusion type helium leak detector are connected with oil. In a device that is connected to an auxiliary exhaust pump such as a rotary pump and that assists exhaust of the inside of the pipe and exhaust of the turbo molecular pump by the auxiliary exhaust pump, drag between the test port and the auxiliary exhaust pump. The above-mentioned object was achieved by interposing a molecular pump.

[0009]

BEST MODE FOR CARRYING OUT THE INVENTION An embodiment of the present invention will be described with reference to FIG. 3. Reference numerals 1 and 1 in FIG. 3 are airtight test chambers in which the airtightness of refrigerator parts, automobile parts, etc. is required. The test bodies 2 and 2 of the article to be stored are stored. The inside of the test body 2 is pre-pressurized with helium gas to about 5 kg / cm ² . To each of the test chambers 1 and 1, an oil rotary pump or an exhaust pump 5 for rough evacuation in which a mechanical booster pump is added to the oil rotary pump is connected via an exhaust pipe 4 provided with opening / closing valves 3 and 3 for rough evacuation. A reverse diffusion type helium leak detector device 8 is connected via an introduction pipe 7 equipped with on-off valves 6 for introducing gas which are opened at the time of inspection. Reference numerals 9 and 9 denote open / close valves for venting to open the inside of each test chamber 1 to atmospheric pressure.

The inverse diffusion type helium leak detector device 8 comprises an inverse diffusion type helium leak detector 12 in which a magnetic field deflection type mass analysis tube 20 is connected to an intake port of a turbo molecular pump 13, and the test chamber 1, 1
The pipe 11 connected to the test port 10 connected to the introduction pipe 7 from the above and the connection pipe 14 connected to the exhaust port of the turbo molecular pump 13 have an exhaust speed of 5 to 10 l / Connected to the auxiliary exhaust pump 15 of about min, the drag molecular pump 17 is provided in the middle of the pipe 11.
And an on-off valve 16 for inspection are sequentially provided in the exhaust direction, and an oil rotary pump is provided through a pipe 21 provided with an on-off valve 18 for auxiliary in a pipe 11 between the drug molecular pump 17 and the on-off valve 16. , Molecular weight pumps such as dry pumps 17
The auxiliary exhaust pump 19 for the vehicle is connected. Although the connection pipe 14 is connected to the pipe 11 after the opening / closing valve 18,
Auxiliary exhaust pump 15 for turbo molecular pump as shown in FIG.
One auxiliary exhaust pump 22 can also serve as the auxiliary exhaust pump 19 for the drug molecular pump. In this case, the on-off valve 16 for inspection is provided in the middle of the connecting pipe 14.

The drug molecular pump 17 has an advantage that it can perform the exhaust operation even in a high pressure flow region which does not reach the molecular flow region. In the turbo molecular pump, the introduction pressure of the suction port is 1 or less.
It is around Pa, whereas the drug molecular pump is 100P
The exhaust operation can be started from about a, and for example, at 10 Pa, exhaust can be performed at a relatively high exhaust rate of 20 l / min. In the leak inspection device, the exhaust pump 5 is installed inside the test chamber 1.
After exhausting to about 10 Pa, the on-off valve 6 for introducing gas is opened, but the drag molecular pump has sufficient reliability in terms of strength against the load at this time.

In the reverse diffusion type helium leak detector device 8 in the standby state, the on-off valve 6 for gas introduction is closed, the on-off valve 18 for auxiliary is opened, and the on-off valve 16 for inspection is closed. Has become. When rough evacuation of the inside of the test chamber 1 containing the test body 2 by the exhaust pump 5 is completed, the opening / closing valve 3 for rough evacuation is closed, and the opening / closing valve 6 for introducing the gas is opened. The open / close valve 18 is closed, and the open / close valve 16 for inspection is opened. As a result, the gas flowing from the chamber 1 flows to the auxiliary exhaust pump 15 via the on-off valve 6 for introducing gas, the drag molecular pump 17, and the on-off valve 16 for inspection, and when there is a leak, helium gas is released. It is diffused in the turbo molecular pump 13 and detected in the mass spectrometer tube 20. When this leakage inspection is completed, the standby state is kept as it is and the degree of residual helium gas in the pipe 11 is monitored, or the auxiliary opening / closing valve 18 is opened immediately and the opening / closing valve 16 for inspection is closed. Since the pipe 11 is provided with a drag molecular pump 17 that performs an exhaust operation even when the introduction pressure is high and has a large exhaust speed, an opening / closing valve 6 for introducing gas when the test chamber 1 is exhausted to about 10 Pa. Can be opened for leak inspection and the pumping speed is high
The helium gas remaining in the chamber 1 can be sufficiently swept, and the test chamber 1 can be replaced with a new one without erroneous recognition of leakage.

The pressure inside the test chamber 1 is 10
^With a high vacuum of ^-2 Pa or less, the conventional reverse diffusion type helium leak detector cannot suck the helium gas flowing out from the test body 2 to the helium leak detector because the auxiliary exhaust pump does not have a pumping speed. Since the apparatus of the present invention is equipped with a drag molecular pump having a sufficient exhaust speed in the molecular flow, even if the inside of the test chamber 1 is in a high vacuum, the leaked helium gas is sucked into the helium leak detector for leak inspection. Can be done reliably. When the internal pressure of the test chamber 1 is sufficiently low, the same effect can be obtained by providing a turbo molecular pump or a composite molecular pump instead of the drug molecular pump 17.

Further, if the auxiliary exhaust pump 15 is an oil rotary pump, there is a problem that the oil mist starts to be released from around 100 Pa, which contaminates the test body 2 in the test chamber 1, and a leak inspection of the semiconductor manufacturing apparatus is performed. However, in the case of the present invention, the drug molecular pump 17 plays a role as a filter, and a leak test can be carried out even on a test body which is unfavorable to contamination of semiconductor manufacturing equipment.

[0015]

DESCRIPTION OF THE PREFERRED EMBODIMENTS To compare the function of the device of the present invention with that of a conventional device, the helium detection capability of the device of the present invention shown in FIG. 3 and the conventional device of FIG. 1 equipped with the helium leak detector of FIG. And the time until the helium gas remained (cleanup time) was investigated.

In the apparatus of the present invention having the configuration shown in FIG. 3, the test chamber 1 has a capacity of 16 liters, and a standard helium leak of 1.7 × 10 ⁻⁷ Torr · l / s is attached to the test chamber 1, and a drug molecule is added. As the pump 17, a pump of 15 liter / s was used. The helium standard leak is an alternative to accommodating the test body 2 in the test chamber 1 and inspecting the leak, and the inside of the chamber 1 is roughly exhausted by the exhaust pump 5 for 20 seconds (until 3 Pa). After that, a helium standard leak was intermittently flown into the chamber 1, and the helium leak detector 8 measured the magnitude of the helium gas output value and the time until the helium gas output value reached the background output value (cleanup time). . The opening time (test time) of the on-off valve 16 for introducing gas was divided into 5 seconds and 10 seconds and performed 10 times each, and the helium gas output value and the cleanup were examined at each time. The results are as in Test Examples 1 and 2 in the following table.

On the other hand, the conventional device shown in FIG.
1.7 × 10 ⁻⁷ To in a 6-liter test chamber b
A helium standard leak of rr · l / s was used. The inside of the chamber b is also 20 by the exhaust pump d.
After performing rough evacuation for 2 seconds (until 3 Pa), a standard helium leak is intermittently flown into the chamber b until the helium leak detector reaches the helium gas output value and the helium gas output value becomes the background output value. The time (cleanup time) was measured. The time (test time) for opening the on-off valve h of the helium leak detector f was divided into 5 seconds and 10 seconds and performed 10 times each, and the helium gas output value and the cleanup were examined at each time. The results are as in Test Examples 3 and 4 in the following table. From the above results, it can be seen that when the test time is 5 seconds, the standard leak output value of the apparatus of the present invention is improved 5.8 times that of the conventional apparatus, and even when the test time is 10 seconds, 3. The standard leak output value is doubled. Also, it can be seen that the test time of the test apparatus was 5 seconds and the apparatus of the present invention was shortened by 4 seconds as compared with the conventional apparatus, and the test time was 10 seconds by 4 seconds.

[0018]

As described above, according to the present invention, the drag molecular pump is interposed in the pipe connected from the test port to the auxiliary exhaust pump in the device for inspecting the leakage by reverse diffusion of the turbo molecular pump. With the relatively high introduction pressure, the reverse diffusion helium leak detector can start the leak inspection, the inspection efficiency is improved, the inside of the pipe can be swept quickly and cleanly, and the false erroneous inspection due to the residual helium gas is reduced. Since it is possible to prevent the contamination of the test body by the pump, there is an effect that the test body that does not like the contamination can be leak-inspected. By arranging the open / close valve according to the second aspect, the effect that the leak inspection can be accurately performed can be obtained.

[Brief description of drawings]

FIG. 1 is an explanatory view of a conventional reverse diffusion type helium leak detector.

FIG. 2 is a schematic diagram of the main part of FIG.

FIG. 3 is a diagram showing an embodiment of the present invention.

FIG. 4 is a diagram showing another embodiment of the present invention.

[Explanation of symbols]

1 test chamber 2 test body,
10 test ports, 11 piping, 1
2 Inverse diffusion helium leak detector, 13 Turbo molecular pump, 14 Connecting pipe, 15 Auxiliary exhaust pump, 17 Drag molecular pump, 16, 1
8 on-off valves,

Claims (1)

[Claims] 1. An auxiliary exhaust pump such as an oil rotary pump having a pipe communicating with a test port connected to a test chamber and a connecting pipe communicating with an exhaust port of a turbo-molecular pump constituting a reverse diffusion helium leak detector. connection,
In a device for assisting exhaust in the pipe and exhaust of the turbo molecular pump by the auxiliary exhaust pump, a drag molecular pump is interposed between the test port and the auxiliary exhaust pump. Leak inspection device.