RU2505883C1 - Method of evacuating gas from instrument and filling it with gas - Google Patents

Abstract

FIELD: process engineering.

SUBSTANCE: proposed method comprises evacuation of the instrument and heating it, forcing gas therein and sealing of the instrument. First, the chamber is pre-evacuated to 5·10^-2 mm Hg and forcing dried nitrogen therein to pressure not over 2 atm. Then, evacuation is terminated to measure vacuum in said chamber. In case degree of vacuum does not change instrument is subjected to oil-free pre-evacuation to 5·10^-2 mm Hg. Instrument is heated during evacuation to not over 100°C. Pumps are disconnected, switched off top force inert gas to not over 1.3 atm. Chambers are filled with nitrogen to seal the instrument by cold exhaust tune solder. Then, evacuation is performed by means of turbo molecular pump to 5·10^-6 mm Hg. Pumps are disconnected, switched off top force inert gas to not over 1.3 atm. Chambers are filled with nitrogen to not over 1.2 at. Chamber is filled with nitrogen to seal the instrument by cold exhaust tune solder.

EFFECT: lower labour input, higher efficiency, longer life.

1 dwg

Description

The invention relates to the electronics industry. The invention can be used in the manufacture of gas-filled solid-state microwave devices. The method provides a continuous processing cycle of the device without exposure to atmospheric air.

A known method of pumping and filling the device with gas. [one]. Gas inlet into the device is metered and can be repeated until the required pressure is obtained, then the device is sealed.

The disadvantages of this method are:

- significant complexity of the inlet;

- a large volume of injected gas,

- gas at the time of filling is cut off from the vacuum system, which degrades the degassing of the device.

A known method of pumping and filling the device with gas - the prototype is [2], the Method includes pumping and heating the device, the inlet of gas into the device and its sealing. At the beginning of pumping and filling the device with gas, a stationary gas flow is established in the pumping system, corresponding to the stationary pressure P _{from the} gas in the device. Upon reaching thermodynamic equilibrium, the device is sealed.

The main disadvantages of this method are:

- the difficulty of establishing thermodynamic equilibrium in the selection of the stationary gas pressure and temperature of getters;

- it is difficult to maintain the relationship between a given gas concentration in the absorbers and the total amount of gas absorbed by the device.

The technical result of the invention is to reduce the complexity of the method of filling with an inert gas of the device and increase the reliability and service life of the device.

The technical result is achieved by the fact that the method of pumping and filling the device with gas comprises pumping and heating the device, letting gas into the device and sealing the device. At the beginning, a fore-vacuum pumping of the chamber to a pressure of 5 · 10 ^-2 mm Hg and the inlet of dried nitrogen into the device to a pressure of not more than 2 atmospheres, then the pumping is stopped and the vacuum in the chamber is measured. If the degree of vacuum has not changed, oil-free forevacuum pumping of the device to a pressure of 5 · 10 ^-2 mm Hg is carried out, and then pumping by a turbomolecular pump to a pressure of 5 · 10 ^-6 mm Hg, the device is heated to a temperature no more than 100 ° C. The pumps are disconnected, turned off and inert gas is injected to a pressure of not more than 1.3 atmospheres. The chamber is filled with nitrogen and the device is sealed with a cold drop of the plug.

Forvacuum pumping of the chamber to a pressure of 5 · 10 ^-2 mm Hg and the inlet of dried nitrogen into the device to a pressure of not more than 2 atmospheres is carried out to control the tightness of the seams of the solid-state device. Such a pumping out of the chamber and filling the device with nitrogen makes it possible to identify leaking seams of the device. And if the seams of the device are not tight, then measuring the vacuum in the chamber detects a change in the degree of vacuum in it. Such a device is removed from the chamber.

If there is no change in the degree of vacuum, then the oil-free forevacuum pumping of the device to a pressure of 5 · 10 ^-2 mm Hg is carried out to provide the possibility of further high-vacuum pumping.

Pumping by a turbomolecular pump to a pressure of 5 · 10 ^-6 mm Hg creates a high vacuum.

During pumping, the device is degassed and hydrocarbon contaminants, as well as water vapor, are removed.

During pumping, the device is heated to a temperature of no more than 100 ° C, since solid-state microwave devices do not withstand a higher temperature.

The pumps are disconnected and then turned off, otherwise inert gas will get into the switched off pump.

The inert gas is poured to a pressure of not more than 1.3 atmospheres, since at higher pressure, the sealed seams of the device that have already been tested with dried nitrogen can be destroyed. In this case, the penetration of gases from the atmosphere is excluded.

For each device, gas has a certain humidity determined by the manufacturing technology of the device.

The chamber is filled with nitrogen to atmospheric pressure to facilitate its rise.

The method of pumping and filling the device with gas is illustrated in the drawing.

Figure 1 presents a device for pumping and filling with inert gas solid-state microwave devices, where

building 1;

countertop 2;

vacuum chamber 3

camera lifting mechanism 4

microwave solid state device 5

device holder 6;

foreline pump 7;

turbomolecular pump 8

collector 9;

gas leakage 10;

sensor for measuring the vacuum in the chamber 11

sensor for measuring vacuum in the device 12

Example.

The solid-state microwave device 5 is installed in the holder 6, mounted on the countertop 2 in a heated vacuum chamber 3, located in the housing 1 of the device for pumping and filling with inert gas. The camera can accommodate several devices at the same time. The vacuum chamber 3 can be lifted above the tabletop 2 by means of a lifting mechanism 4. Under the tabletop 3 there is a system for creating a vacuum including a vacuum pump 7 oil-free spiral type and a turbomolecular pump 8 and a manifold 9 connected to the gas leak 10. The vacuum in the chamber is measured by a sensor 11 The vacuum in the device is measured by the sensor 12. Before the inert gas is supplied to the leakage 10, its humidity is measured. Inert gas is formir gas.

The device operates as follows.

Instruments 5 are mounted in holders 6 in the heated vacuum chamber 3. The chamber 3 is hermetically sealed, the fore-vacuum pump 7 is turned on, and the chamber is pumped out to a pressure of 5 · 10 ^-2 mm Hg. Through the collector 9 and holders 6, dried nitrogen is introduced into the devices 5 with an overpressure of 2 atmospheres. The pumping is stopped and the vacuum is measured by the sensor 11. If a change in the degree of vacuum is detected, nitrogen is injected into the chamber 3 to atmospheric pressure and opened using the lifting mechanism 4. Each device 5 is blown with helium and its leak tightness is checked by a leak detector. Defective device 5 is removed from the holder 6.

If the degree of vacuum has not changed, then the seams of the devices 5 are tight. Turn on the fore-vacuum pump 7 and pump out the device 5 to a pressure of 5 · 10 ^-2 mm Hg. Then turn on the turbomolecular pump 8 and continue pumping to a pressure of 5 · 10 ^-6 mm RT.article The devices 5 in the chamber 3 are heated by halogen lamps to a temperature of not more than 100 ° C, as a result, the devices are degassed 5. The collector 9 is heated by a nichrome spiral to 250 ° C and degassed. Pumps 7 and 8 are disconnected from the device and turned off. From the leakage 10 through the collector 9 in the holders 6 serves inert gas. Devices 5 are filled with inert gas to a pressure of not more than 1.3 atmospheres. Then nitrogen is introduced into the chamber to atmospheric pressure and the chamber is raised. They seal the devices with cold junction on the dowels.

The effectiveness of the proposed method was tested in the manufacture of a powerful microwave amplifier PM24-C8 on an experimental device.

The results obtained suggest that the reliability and service life of the device will increase by an order of magnitude. When pumping and filling small-sized devices, productivity increases 5 times.

Information sources

1. Roseberry F. Handbook of Vacuum Engineering and Technology. M .: "Energy", 1978, p. 80.

2. Patent RU No. 2195041, H01J 9 | 38 - prototype.

Claims (1)

A method of pumping and filling the device with gas, comprising pumping and heating the device, letting gas into the device and sealing the device, characterized in that the chamber is evacuated to a pressure of 5 · 10 ^-2 mm Hg at the beginning. and the inlet of dried nitrogen into the device to a pressure of not more than 2 atm, the pumping is stopped and the vacuum in the chamber is measured, if the degree of vacuum has not changed, then the oil-free fore-vacuum pumping of the device to a pressure of 5 · 10 ^-2 mm Hg, and then pumping out by turbomolecular pump to a pressure of 5 · 10 ^-6 mm Hg, the device is heated to a temperature of not more than 100 ° C during pumping, the pumps are disconnected from the device, turned off and inert gas is admitted to a pressure of not more than 1.3 atm, the chamber is filled with nitrogen to atmospheric pressure and seal the device with a cold seal exhaust tube.