JPH01201131A - Airtightness testing method - Google Patents

Abstract

PURPOSE:To increase the durability of bellows by producing a vacuum inside and outside the bellows and conducting a test without any stress due to the pressure difference. CONSTITUTION:The airtightness of the bellows 4 is tested by using the device having the bellows put in a vacuum chamber 5. While all solenoid valves 11, 12, and 15-17 are closed, the bellows 4 are put on a sample table 8 across an O ring 9 and a lid part 7 is mounted on a holding part 6. Then the valves 11 and 15 are opened at the same time to obtain the desired degree of vacuum and then the valve 15 is closed while the valve 17 is opened to admit He, thereby detecting whether or not there is a leak by an He detector in this state. The valves 11 and 17 are closed and the valves 12 and 16 are opened at the same time after the test to put the inside and outside of the bellows 4 back to the atmospheric pressure, thereby taking the bellows out.

Description

[Detailed Description of the Invention] [Summary] Regarding the airtightness test method for bellows, the purpose is to conduct the airtightness test without impairing the durability of the bellows, by evacuating the inside of the bellows and simultaneously evacuating the outside of the bellows. , constitutes an airtightness test method by testing the airtightness without applying stress due to pressure difference to the bellows.

[Industrial application field]

The present invention relates to a method for testing the airtightness of bellows.

BACKGROUND OF THE INVENTION Due to the need to process large amounts of information at high speed, information processing devices have made remarkable progress, and the semiconductor elements forming the main body of these devices have increased in capacity, and LSIs and VLSIs have come into practical use.

Now, as a mounting method for these semiconductor elements, alumina (
LSI packages are mounted in a matrix on a multi-layered VA board made of ceramics such as α-Al zOi), but the LSI chips housed in the LSI package consume a lot of power and generate heat. It has become extremely difficult to maintain the temperature of LSI chips within the maximum operating temperature using the conventional forced air cooling method.

Therefore, instead of conventional air cooling, liquid cooling is used as a cooling method.
One example of this is that in LSI packages, an elastic heat transfer element with bellows is placed in close contact with the heat transfer substrate on which the LSI chip is mounted, and cooling water is passed through the elastic heat transfer element. A method of forcibly cooling the heat transfer substrate is being considered.

Here, the LSIs arranged in a matrix on the board
In order to water-cool the elastic heat transfer elements arranged in a matrix on the thermal base of the package in close contact with each other, the elastic heat transfer elements must be formed with elasticity.

The present invention relates to a method for testing bellows used in such applications.

[Conventional technology]

The bellows are made of an elastic metal such as beryllium% (Be-Cu) + H bronze, and are formed into a cylindrical shape with folds on the sides; however, the bellows used here has one end surface made of copper ( It is sealed with a heat transfer plate with good thermal conductivity such as Cu).

As shown in Fig. 3, the airtightness test method for bellows is as follows:
The bellows 4 to be tested through the O-ring 1 after being inserted into the test port of the helium (He) leak detector
and operate the exhaust system to make the inside of bellows 4 10-
' With the pressure reduced to approximately torr, lie gas is blown from the outside of the bellows 4, and the H that has passed through the bellows 4 is
Airtightness was measured by mass spectrometry of e-gas.

However, according to this method, the bellows 4 is deformed due to a large pressure difference between the inside and outside of the bellows 4.

FIG. 2 is a cross-sectional view (A) of the bellows 4 before evacuation and a cross-sectional view (B) after evacuation, and since the bellows 4 is made of elastic metal, extreme contraction occurs after evacuation. There were problems in that durability decreased and, depending on the material, permanent deformation occurred, resulting in defective products, and it was necessary to improve the testing method.

(Problems to be Solved by the Invention) As described above, when testing the airtightness of a bottomed bellows using a He leak detector, the conventional method creates a large pressure difference between the outside and the outside of the bellows. The problem is that deformation occurs, reducing durability and, depending on the material used, causing permanent deformation and resulting in defects.

[Means for solving problems]

The above problem is solved by installing a bellows to be tested on a sample stand that has a first electromagnetic valve and a first electromagnetic leak valve, and has an exhaust path in the center that connects to a helium leak detector. An airtight vacuum chamber equipped with a second solenoid valve for shutting off the exhaust path connected to the exhaust system via an O-ring, a third solenoid valve for helium gas supply, and a second solenoid leak valve at the top of the vacuum chamber prepared for Using a test device, open the first solenoid valve and the second solenoid valve at the same time to reduce the pressure inside and outside the bellows to a vacuum, then close the second solenoid valve and open the third solenoid valve to reduce the pressure in the vacuum chamber. This can be solved by using an airtightness test method in which a helium gas atmosphere is created under reduced pressure and the airtightness of the bellows is detected using a helium leak detector.

[Effect]

When testing the airtightness of easily deformed parts such as bottomed bellows, the sensitivity of the He'J-Kuditech tester is very excellent. 760 torr outside the bellows, approximately 10 torr inside the bellows
This was done after confirming that the presence or absence of a leak can be detected with the same precision as in the past even if there is an air pressure difference of about 1 digit even without the presence of a pressure difference of -'torr), while the bellows hardly deforms.

Since the mass spectrometer that makes up the He leak detector cannot operate unless it is in a high vacuum, we decided to achieve this one-digit pressure difference in a high vacuum state, and installed the bellows in an airtight container. After simultaneously evacuating the inside and outside of the bellows to create a high vacuum state, the exhaust path outside the bellows is closed and He gas is supplied to achieve a pressure difference that does not cause large deformation of the bellows.

By adopting such a method, the presence or absence of a leak can be detected without impairing the durability of the bellows.

〔Example〕

FIG. 1 is a cross-sectional view of the airtightness testing apparatus used in carrying out the present invention.

This device is composed of a holding part 6 and a lid part 7, each of which has a vacuum chamber 5 in which a bellows 4 is installed.

The holding unit 6 includes a sample stage 8 in a vacuum chamber 5, and a bellows 4 is installed via an O-ring 9.

Here, the exhaust path 10 reaching the center of the sample stage 8 is provided with a first solenoid valve 11 and a first electromagnetic leak valve 12, and the mounting part 13 is provided at the tip of the exhaust path 10. li
It is configured to be inserted and fixed into the test port of the e-leak detector.

In addition, a groove is provided on the upper surface of the holding part 6.
A ring 14 is fitted.

Next, the lid part 7 has a second solenoid valve 15 that opens and closes the exhaust system.
A second electromagnetic leak valve 16 and a third electromagnetic valve 17 for opening and closing the I(e gas passage) are provided.

As a test method using such an airtight test device, the bellows 4 is placed on the sample stage 8 via the O-ring 9 with all the solenoid valves 11, 12, 15, 16, 17 closed, The lid part 7 is attached onto the holding part 6 via the O-ring 14.

Next, the first solenoid valve 11 and the second solenoid valve 15 are simultaneously opened to exhaust the inside and outside of the bellows 4 to approximately 1 O-6 torr.

After reaching a predetermined degree of vacuum, the second solenoid valve 15 is closed, the third solenoid valve 17 is opened, and a small amount of He gas is introduced.
-'torr, and in this state, the presence or absence of a leak is detected by a He leak detector.

After the test is completed, the first solenoid valve 11 and the third solenoid valve 17 are closed, and the first solenoid leak valve 12 and the second solenoid leak valve 1 are closed.
6 at the same time to bring the inside and outside of the bellows 4 to atmospheric pressure and take it out.

By adopting such a method, the airtightness test can be performed without causing almost any deformation of the bellows 4.

〔Effect of the invention〕

By implementing the present invention, it becomes possible to perform airtightness tests on bellows without reducing durability or causing permanent deformation of the bellows.

[Brief explanation of the drawing]

Figure 1 is a cross-sectional view of the airtightness test device used to implement the present invention, Figures 2 (A) and (B) are cross-sectional views explaining the deformed state of the bellows, and Figure 3 is an explanation of the conventional airtightness test method. FIG. In the figure, 1.9.14 is an O-ring, 4 is a bellows, 6 is a holding part, 7 is a lid part, 8 is a sample stage, 11 is a first electromagnetic valve, 12 is a first electromagnetic leak valve, and 15 is a a second solenoid valve, 16 is a second solenoid valve;
The electromagnetic leak valve 17 is a third electromagnetic valve. Tsubokifu Seikifuimo 3 Figure

Claims (2)

[Claims] (1) In a bellows airtightness test method using a helium leak detector, the airtightness is tested without applying stress to the bellows due to pressure differences by creating a vacuum inside the bellows and simultaneously creating a vacuum outside the bellows. An airtightness test method characterized by: (2) First solenoid valve (11) and first solenoid leak valve (1
2), the bellows (4) to be tested is installed on a sample stand (8) equipped with an exhaust path (10) connected to a helium leak detector in the center, and the sample stand (8) is provided inside. An O-ring (14) is attached to the top of the vacuum chamber (5).
) and a third solenoid valve (17) for supplying helium gas.
) and a second electromagnetic leak valve (16), open the first electromagnetic valve (11) and the second electromagnetic valve (15) at the same time, and check the inside and outside of the bellows (4). After reducing the pressure to vacuum,
The second solenoid valve (15) is closed and the third solenoid valve (17) is opened to create a reduced pressure helium gas atmosphere in the vacuum chamber (5), and the airtightness of the bellows (4) is detected by a helium leak detector. An airtightness test method according to claim 1, characterized in that: