JPS649700B2 - - Google Patents

Description

TECHNICAL FIELD OF THE INVENTION The present invention relates to a method for manufacturing an evaporative, oxidation-resistant getter device that adsorbs residual gas in an electron tube such as a receiving tube, an X-ray tube, or a cathode ray tube.

Technical background of the invention and its problems Getter devices can be roughly divided into evaporative getter devices that adsorb residual gas on a thin film obtained by evaporating barium in the vacuum region of an electron tube, etc., and getter devices that use titanium, zirconium, tantalum, etc. There are two types of getter devices: a non-evaporable getter device, which is placed in a vacuum region to perform a getter action. Of these, barium is widely used as a substance that adsorbs evaporated substances, that is, residual gas, in evaporative getter devices, but barium-aluminum (hereinafter referred to as Ba-Al) is easily oxidized in the atmosphere.
) is made into a powder and used as a getter material. Furthermore, the getter device that is mainly used is one in which a reaction additive (reducing metal) powder such as nickel powder is mixed with Ba-Al alloy powder and the mixture is filled into a conductive container. This is because when the getter device is heated, the aluminum in the Ba-Al alloy powder reacts with the nickel powder (reactive additive).
The heat of reaction facilitates the evaporation of barium. The above-mentioned getter device heats by high-frequency heating or the like to form a getter film of barium on the inner wall of the vacuum chamber.

However, before the getter device is evaporated, the getter device is often subjected to undesired heating, and the getter material, mainly nickel, may be oxidized, which may interfere with the formation of the getter film. Also,
In order to make cathode ray tubes smaller and more energy efficient, the diameter of the net is made smaller, and in order to make the getter device function more fully, the shape of the getter device is made larger, making it difficult to insert it through the neck. Ta. Furthermore, it has been confirmed that it is better not to insert the getter device through the funnel neck in order to electrically disconnect the getter device from the electron gun and prevent undesired surge current from flowing between the getter device and the electron gun. has been done.

For example, this is the case as disclosed in British Patent No. 1226728. According to this disclosed example, the getter device is installed inside the cathode ray tube before the panel portion and the funnel portion that constitute the cathode ray tube are sealed together with frit glass. Thereafter, fritted glass is applied to the sealed portion between the funnel and the panel in the atmosphere, and a high temperature treatment is performed at 450° C. for 1 hour to complete the sealing. At this time, the getter device filled with a mixed powder of Ba-Al alloy powder and nickel powder is oxidized during the high temperature treatment at 450°C for 1 hour in the atmosphere during the above sealing process, and is mainly made of nickel oxide (hereinafter referred to as (referred to as NiO). If NiO is present in the getter device, NiO and the Ba-Al alloy powder will react rapidly at high temperatures, resulting in explosive barium scattering when the getter device is heated to evaporate barium (hereinafter referred to as getter flash). This brings about the result. If a large amount of NiO is produced, there is a risk that the metal container itself will be fused and exploded together with the getter material. For example, in cathode ray tubes for color television, this type of explosive scattering must be avoided at all costs, as it causes poor pressure resistance and impairs tube function. For the above reasons, there is a need for a getter device that does not cause any trouble even when exposed to high temperatures in the atmosphere. For this purpose, a getter device whose surface was coated with organic silane was published in JP-A-52
A getter device coated with silicon oxide is disclosed in Japanese Patent Laid-Open No. 139355-1984. A getter device coated with boron oxide is disclosed in JP-A-56-61736.

According to Japanese Patent Application Laid-Open No. 52-84960, alkyl,
It has been demonstrated that Getta devices coated with organic silanes such as aryl, aralkyl, alkaryl, and hydrogen-containing polysiloxanes can withstand heating in air at 420°C for 1 hour and evaporate barium without exhibiting explosive scattering. It is shown. However, when a getter flash is performed using a getter device coated with such an organic silane, a large amount of mainly hydrocarbon-based gases are released from the organic silane, and these gases are not easily adsorbed by the getter film, and the getter flash is A problem arises in that the pressure inside the pipe remains at around 10 ^-3 Torr for a while. Such a large amount of residual gas is ionized in a space loaded with high voltage, such as in a cathode ray tube for a television, and is accelerated and collides with the cathode or anode, causing a sputtering phenomenon. Due to this sputtering phenomenon, a part of the electron-emitting substance on the cathode flies to other undesirable locations, significantly deteriorating the withstand voltage characteristics, or causing so-called ion spots on the anode side.

Also, a getter device coated with a silicon oxide layer as shown in Japanese Patent Application Laid-Open No. 52-139355 exhibits considerable protection against high temperature oxidation. That is, when the getter device was heated in the atmosphere and then flashed, the degree of explosive scattering was considerably improved, but a small amount of getter material fell off and some sintered getter material floated outside the container. It was done.

However, in order to prevent deterioration of the voltage resistance characteristics of electron tubes such as cathode ray tubes, it is necessary to completely avoid explosive scattering, lifting of the getter material, and falling off of the getter material during getter flashing, even if it is slight. In other words, explosive scattering occurs when particles fly to undesired locations inside the pipe.
This may cause not only deterioration of withstand voltage characteristics but also a short circuit in the circuit. In addition, when the getter flush is carried out, the rising of the getter causes a barium film to be formed in undesired areas inside the pipe, causing deterioration of the pressure resistance characteristics.After the getter flushing, the getter residue falls into the pipe, causing dust in the pipe. This causes severe damage to pipe function.

Further, when the surface of the getter device coated with the silicon oxide layer was observed using an electron microscope, it was found that the silicon oxide layer had a porous structure. That is, oxygen is supplied to the surface of the getter device through these pores, and a part of the getter material, mainly the nickel powder, is oxidized. The oxidation of the nickel powder in this getter material is thought to be the cause of the explosive scattering, even if it is mild.

Also, in Japanese Patent Application Laid-Open No. 56-61736,
A getter device is disclosed in which Ba--Al alloy powder and nickel powder are coated with boron oxide. In coating the getter device with this boron oxide,
After the boron oxide is dissolved in a solvent, it is coated on the getter device by dipping, spraying, or the like. On this occasion,
The solvent used was alcohol, and methyl alcohol, for example, has the property of reacting with boron oxide to form a volatile ester having a composition such as B(OCH ₃ ) ₃ . When boron oxide is dissolved using alcohols such as methyl alcohol, ethyl alcohol, propyl alcohol, butyl alcohol, etc., a volatile ester is created, so the concentration of boron oxide changes over time and the amount of coverage remains constant. The problem was that it was difficult to do so. In other words, because the coating amount of the manufactured oxidation-resistant getter device is not constant and varies, it cannot fully demonstrate the effect of preventing NiO generation, and even though an explosive reaction does not occur, the getter material lifts up and scatters. There were problems in that the amount was not constant and the time taken until the getta flush started differed in each case. To eliminate these drawbacks, measure the amount of boron oxide dissolved in the alcohol solvent when coating the getter device with boron oxide, and try to keep the amount of dissolved boron oxide constant. It is necessary to hold a candle. However, as mentioned above, boron oxide dissolved in alcohol forms ester, and the evaporation rate is very fast, making it difficult to keep the dissolved boron oxide constant.

This problem will be explained in detail as follows. 1st
The second method is to dissolve 10% by weight of boron oxide in methyl alcohol, immediately immerse the getter device in the solution, dry it in the air at 150℃ for 2 hours using an electric dryer, and then dry it in a vacuum at 500℃ for 30 minutes. The getter device was coated with boron oxide by heating for a minute. As a second method, the getter device is coated with boron oxide using the same process as the first method, using a solution in which 10% by weight of boron oxide is dissolved in methyl alcohol and left for 6 hours. Ta. The getter device manufactured by the first method exhibited good characteristics as a getter device without any lifting phenomenon when flushed, whereas the getter device manufactured by the second method was the same as the first method. When the material was flushed under certain conditions, a floating phenomenon occurred. This is because boron oxide in the solution reacts with methyl alcohol to produce esters such as B( _OCH3 ) ₃ , which reduces the amount of boron oxide coated on the getter device, and also reduces the amount of boron oxide that is dissolved. This shows that it is difficult to keep boron oxide constant. Furthermore, it was confirmed that when water is used as a solvent to dissolve boron oxide, water causes oxidation of the Ba-Al alloy powder in the getter material, making it impossible to use water as a solvent.

Purpose of the Invention The purpose of the present invention was made in view of the above points, and it is an object of the present invention to provide a method for manufacturing a high-quality getter device that has high temperature oxidation resistance and does not cause any trouble when used. There is a particular thing.

Summary of the Invention The present invention involves applying a solution of boron oxide dissolved in a solvent that does not generate volatile esters to a getter or a getter device filled with a getter material and drying the solution to coat the getter or getter device with boron oxide. An oxidation-resistant getter device is manufactured using the same method. Even if this solution is allowed to stand for some time, it will not cause any problems in the production of oxidation-resistant getter devices. The oxidation-resistant getter device manufactured according to the present invention is not affected by high temperature treatment during sealing between the funnel and the panel.

EXAMPLES OF THE INVENTION Example 1 FIG. 1 is a sectional view of an oxidation-resistant getter device obtained according to the present invention. This oxidation-resistant getter device 10 has an outer diameter of 22.0 mm, an inner diameter of 15.0 mm, a height of 2.7 mm, and a thickness of
A getter material 11 is filled in an open annular metal getter container 12 made of inductive steel and having a U-shaped cross section with a diameter of 0.18 mm. In this example, the weight composition ratio of Ba-Al alloy powder, nickel powder, and germanium nitride-iron powder as the getter material was approximately 49:49:2.
Adjusted to. Then, this getter device 10 was immersed in an ethylene glycol monomethyl ether solution containing 10% by weight of boric anhydride, dried in the air at 150°C for 2 hours using an electric dryer, and heated in vacuum at 500°C for 30 minutes. Then, the getter container 12 of the getter device 10 was coated with a thin boron oxide 13.
When the oxidation-resistant getter device manufactured in this manner was subjected to getter flashing, it exhibited good characteristics without any explosive barium scattering or floating phenomenon. Further, a boron oxide coating was formed on the getter device in the same manner as in the above case using the solution that was left to stand for 12 hours after solution generation. When this getter device was subjected to a getter flash, it showed good characteristics without any explosive barium scattering or floating phenomenon, similar to the above-mentioned example. This shows that the getter function of the getter device does not deteriorate even if the getter device is manufactured using a solution that has been left for a while after solution generation.

Example 2 Next, a case will be described in which the getter device of Example 1, which was made using a solution that was left to stand for 12 hours after solution generation, was actually used in a cathode ray tube. FIG. 2 is a partially cutaway sectional view of the cathode ray tube 31. As shown in FIG. 2, a fluorescent screen 21 and an aluminum vapor deposition surface 22 are sequentially formed on the inner surface of a front glass panel 20, and a frame 24 is formed.
The shadow mass 23 attached via the panel is supported and fixed to the side wall of the panel. Next, the getter device 25 obtained according to the present invention is attached to the frame 24 via the support plate 26. After that, a fritted glass 29 is applied to the contact surface between the funnel 28 whose inner surface is coated with the conductive film 27 and the glass panel 20,
A high-temperature treatment at about 450° C. for 1 hour seals the two together and evaporates the organic material between the fluorescent film and the metal back coating. After this, connect the electron gun to the net section 30.
The cathode ray tube 31 is sealed through an evacuation process. Thereafter, the cathode ray tube 31 is completed through getter flashing by high frequency induction heating, aging of the electron gun, etc. In this case as well, the same effects as in Example 1 were obtained. It was confirmed that the cathode ray tube thus obtained had electron emission characteristics and breakdown voltage characteristics equivalent to those of a cathode ray tube in which a getter device was attached to an electron gun.

Furthermore, when installed in a cathode ray tube or the like before sealing the funnel and panel, the getter device manufactured by the manufacturing method of the present invention will not undergo any change due to high temperature treatment and will retain its original getter device. Indicates that it has an effect. In this case, 450℃ of Example 2
The conditions are stricter than the one hour high temperature treatment at 450℃2.
It was treated at high temperature for an hour. There are two types of getter devices to be tested: The first getter device is one in which a coating of boron oxide is formed using a solution immediately after the solution is generated. The second getter device produces a solution 12
A coating is formed using a solution that is left to stand for a period of time. When the first getter device and the second getter device were respectively flushed, no lifting of the getter material or the getter material coming out of the getter container was observed in both getter devices. Furthermore, no explosive scattering of barium, which tends to occur during gettuta flushing, was observed. Therefore, by using the production method of the present invention, a solution in which boron oxide is dissolved can be left for a while.

Next, the effect of a solvent that does not react with a boron oxide to form an ester as in the present invention will be explained in detail with reference to FIG.

In Figure 3, the horizontal axis shows the time the solution was left to stand after dissolving boron oxide in the solvent, and the vertical axis shows the amount of boron oxide dissolved in the solution compared to the boron oxide initially dissolved in the solvent. It is shown in terms of weight composition ratio. As shown in characteristic 41 using methyl alcohol as the solvent, the boron oxide in the solution decreases as the solution is left for a longer time. In other words, even if the getter device is coated with boron oxide using a solution that has been left for a while after formation, the amount of coating will be less than the initially set amount. It is estimated that it will be difficult to achieve the objectives of On the other hand, as shown in characteristic 42 when ethylene glycol monomethyl ether is used as the solvent, the amount of boron oxide dissolved in the solution remains approximately constant even if the solution is left for a while. This is because the solvent and boron oxide do not react to form ester and boron does not evaporate. That is, it is presumed that by using the solvent of the present invention, even if a getter device is manufactured using a solution that has been left for a while after being produced, the object of the present invention, such as preventing getters from floating during getter flushing, can be sufficiently achieved. Ru.

Furthermore, as shown in FIG. 4, the use of the method for manufacturing an oxidation-resistant getter device of the present invention is useful for preventing the oxidation of the getter material, which is the cause of the lifting of the getter material of the getter device and the explosive scattering of barium during getter flushing. This is explained in detail.

Figure 4 shows that oxidation-resistant getter devices were manufactured using solutions prepared by adding 10% by weight of boric anhydride to methyl alcohol and ethylene glycol monomethyl ether as solvents, and then heated at 450°C in the air for 2 hours. The weight increase due to oxidation was investigated by high-temperature treatment. The horizontal axis shows the standing time after producing the solution used to manufacture each oxidation-resistant getter device, and the vertical axis shows the high temperature treatment at 450°C for 2 hours in the atmosphere (hereinafter referred to as atmospheric treatment). The weight composition ratio obtained by dividing the oxidation weight gain of each oxidation-resistant getter device by the amount of nickel powder contained in the getter material when performing this is shown. At this time, the oxidation weight increase was divided by the amount of nickel powder because it is mainly the nickel powder that is oxidized. Characteristics of oxidation-resistant getter device when methyl alcohol is used as a solvent 51
As shown in Figure 2, when the solution is treated immediately after it is produced (the standing time is 0 hours), the oxidation weight increase is 0.20% by weight when the atmospheric treatment is performed, and even when the getter flush is performed, the lifting phenomenon and the getter material do not occur. However, no particles were observed to come out of the container (hereinafter referred to as a peeling phenomenon). However, when a solution was produced and left to stand for 6 hours, the oxidation weight increase was 0.70% by weight after atmospheric treatment, and a lifting phenomenon was observed when Getta flushing was performed. Furthermore, when a solution was produced and left for 12 hours, the weight increase by oxidation reached as much as 2.00% by weight after atmospheric treatment, and when Getta flushing was performed, the lifting phenomenon became noticeable, and even the peeling phenomenon was observed. In contrast, as shown in Characteristics 52 of the oxidation-resistant getter device when ethylene glycol monomethyl ether is used as a solvent, if the solution is allowed to stand for 12 hours after being formed and then treated in the atmosphere, the weight gain due to oxidation is 0.24% by weight. No lifting or peeling phenomena were observed even after Getta flushing was performed.

Therefore, by adopting the method for manufacturing an acid-resistant getter device of the present invention, it is possible to prevent the oxidation of the getter material, which is the cause of the lifting and peeling phenomenon of the getter material of the getter device and the explosive scattering of barium during getter flushing. It was confirmed that it is useful for

As in the above embodiment, the getter device is now able to maintain a constant thickness of the boron oxide coated on the getter material. This is because the solvent that dissolves boron oxide was changed to an alcohol, which did not react with boron oxide to form an ester. Therefore, the amount of boron oxide coated on the getter material can be adjusted as appropriate. Therefore, when the getter device of this example is flashed by high-frequency induction heating, the reactivity between the Ba-Al alloy powder and the nickel powder is as good as that of the conventional getter device not coated with boron oxide, and The scattering start time was also not impaired.

In addition, the Getsuter device can be exposed to air for 2 hours, for example.
During high-temperature treatment at 450°C, the nickel powder was not oxidized, and NiO was not formed to cause a rapid reaction between NiO and the Ba-Al alloy powder. Since the getter material can be uniformly coated with boron oxide, the cause of lifting and other problems can be fundamentally solved.
The getter device of this embodiment is disclosed in Japanese Patent Application Laid-Open No. 56-61736.
Unlike the method for manufacturing an oxidation-resistant getter device disclosed in the publication, high reliability was confirmed even when the getter device was manufactured by leaving a solution containing boron oxide dissolved therein for a while after it was produced. Furthermore, when we measured the distribution of the barium film formed by the getter flash, the amount of barium scattered, and the amount of released gas (mainly nitrogen gas, etc.), the results showed that the getter device had the same characteristics as the conventional getter device not coated with boron oxide. It was confirmed that the original role of the device was not impaired.

In the above-described embodiment, a process was described in which the getter device filled with the getter material was immersed in an ethylene glycol monomethyl ether solution containing 10% by weight of boric anhydride. However, only the getus wood was soaked in an ethylene glycol monomethyl ether solution containing boron oxide, dried in the air at 150°C for 2 hours using an electric dryer, and then heated in a vacuum at 500°C for 30 minutes. The getter device may be manufactured by coating the boron oxide and filling the getter container. Further, when coating the getter material and the getter device with boron oxide, a solution in which the boron oxide is dissolved may be applied to the getter material and getter device by spraying or the like. Furthermore, in the examples, ethylene glycol monomethyl ether alone was used as the solvent, but in addition to this, for example, a single or mixed solution of ethylene glycol monoethyl ether, ethylene glycol mono-n-butyl ether, and ethylene glycol monomethyl ether may be used. may be used as a solvent. It goes without saying that the mixing ratio of the solvents may be any ratio.

Effects of the Invention As described above, according to the present invention, since the solvent for dissolving boron oxide does not generate volatile esters that react with boron oxide, there is little change in solution concentration over time, so there is no effect on the timing of solution generation. The thickness of the boron oxide coated on the getter material can always be kept constant. The solvent and boron oxide react to form an ester, and since the boron oxide in the solution does not evaporate, the solution can be left for a considerable period of time after the boron oxide is dissolved, making it very easy to manage the solution. becomes easier. Further, according to the method for manufacturing an oxidation-resistant getter device of the present invention, the getter material may be coated with boron oxide after the getter device is manufactured, so the oxidation-resistant getter device can be manufactured easily and inexpensively. It is estimated that mass production will become easier and a getter device of higher quality can be manufactured.

[Brief explanation of drawings]

Fig. 1 is a cross-sectional view of an oxidation-resistant getter device obtained by the present invention, Fig. 2 is a partially cutaway cross-sectional view of a cathode ray tube, and Fig. 3 shows that boron oxide and solvent do not react to form an ester. Diagram showing the effect of solvent, 4th
The figure shows the standing time and oxidation of the getter material after the formation of a solution containing dissolved boron oxide. 10... Oxidation-resistant getter device, 11... Getter material,
12...Getter container, 13...Boron oxide, 42...
Characteristics using ethylene glycol monomethyl ether as a solvent, 52...Characteristics of an oxidation-resistant getter device using ethylene glycol monomethyl ether as a solvent.

Claims (1)

[Claims] 1. A step of dissolving the boron oxide in a solvent excluding water that does not react with the boron oxide to produce volatile esters to form a solution, and using the solution as a getter material or maintaining the getter material as metallic. An oxidation-resistant getter comprising the steps of applying it to a getter device filled in a container, and drying the getter material or the getter device to coat the getter material or the getter device with boron oxide. Method of manufacturing the device. 2 After coating the getter material with boron oxide,
2. The method of manufacturing an oxidation-resistant getter device according to claim 1, further comprising the step of filling a metal holder with the getter material. 3. The step of applying the solution to the getter material or the getter device in which a metal holder is filled with the getter material is a step of immersing the getter material or the getter device in which the getter material is filled in a metal holder in the solution. The first claim characterized in that
A method for manufacturing an oxidation-resistant getter device as described in . 4. The step of applying the solution to the getter material or the getter device in which the getter material is filled in a metal holder is a step of spraying the solution onto the getter material or the getter device in which the getter material is filled in a metal holder. A method for manufacturing an oxidation-resistant getter device according to claim 1, characterized in that: 5. The oxidation-resistant agent according to claim 1, wherein the solvent is a single substance or a mixed solution selected from the group consisting of ethylene glycol monomethyl ether, ethylene glycol monoethyl ether, and ethylene glycol mono n-butyl ether. A method of manufacturing a sex getter device.