JP2804288B2 - High temperature operating element - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Application Field] The present invention relates to a high-temperature operating element that is operated by being heated to a high temperature of about 1000 ° C. by a heater, for example, a cathode ray tube using hot electron emission, a hot cathode X-ray tube, The present invention relates to the structure of a high-temperature operating element such as an electron microscope and an electron gun for a cathode ray tube.

[Prior Art] Conventionally, a high-temperature operating element has been manufactured by using a so-called thick film circuit forming technique such as screen printing, as described in Japanese Patent Application Laid-Open No. 55-24646. FIG. 3 is a sectional view showing a conventional high-temperature operating device manufactured in this manner. First, a raw material constituting a ceramic substrate (10) is prepared, and a heating element layer (11) having a predetermined pattern is formed on a sheet by a printing technique such as an extrusion method passing between rolls or a casting method. An insulator (12) is formed on the substrate (10) on which the heating element layer (11) is formed, and a cathode material layer (13) and a cathode are formed on the insulator (12) by a similar printing method. A lead layer (14) and a base metal layer (15) are formed to form a high-temperature operating element. The heating element layer (11) is formed by screen-printing a paste obtained by adding a firing aid to a heater material, and the operating element is similarly formed by screen-printing a paste obtained by adding a firing aid to a desired material on a substrate (10). . After screen printing, high temperature (1000 ~
(2000 ° C.) to form a high-temperature operating element.

In this method, since a high-temperature processing step is performed at the time of manufacturing, when the heater is used at a temperature lower than this processing temperature, high-temperature long-term stability as a heater such as a small change in resistance over time can be obtained. However, the pattern accuracy obtained by screen printing is low, and the thickness control (thinning) of the heating element layer (11) is difficult, so that the power consumption is large and the resistance variation among a plurality of heaters is large. Therefore, the development of a film forming method by PVD or CVD has been promoted as a method capable of forming a pattern with high accuracy.

FIG. 4 shows a conventional method for manufacturing a high-temperature operating device by a thin film forming method. First, a resistor (heating element) film (2) for a heater is uniformly formed on a smooth ceramic substrate (1), and a high-temperature operating element film (4) is uniformly formed on the opposite side. A high-temperature operating element has been realized by forming a heater pattern and an element pattern, and bonding a lead wire (5) to the heater side.

[Problem to be Solved by the Invention] In the conventional high-temperature operating element using the above-described film forming method, a voltage is applied to the lead wire (5), and the resistance changes while the element is used as a heater. This is mainly due to the fact that the resistor (heating element) film (2) is a thin film. FIG. 5 shows the change over time in the resistance value. The initial drop in resistance is
This is because recrystallization of the thin film proceeds and crystal grains in the film become coarse. For example, when the resistor (heating element) film (2) is W (tungsten) and is used at 1000 ° C., recrystallization proceeds because 1000 ° C. corresponds to the recrystallization temperature of W. Next, the reason why the resistance increases with time is that impurities are mixed into the film or oxidized depending on the atmosphere during use. Therefore, the heater is unstable and lacks long-term reliability. In addition, there has been a problem that the film is separated from the substrate due to the internal stress of the film during use, and the performance of both the heater and the element becomes insufficient.

As described above, for a high-temperature operating element, a porous film having a low film density is provided on both sides by a thick film circuit forming technique, or a dense film having a small adhesive force and a high film density is provided by a thin film forming method. , And both the heater and the element did not exhibit sufficient performance.

SUMMARY OF THE INVENTION The present invention has been made to solve the above-mentioned problems of the conventional high-temperature operating device, and has as its object to provide a high-temperature operating device with high long-term reliability.

[Means for Solving the Problems] A high-temperature operating element according to the present invention is formed by forming a porous high-temperature operating element film having a low film density in a predetermined shape on one surface of an insulating member. A resistor film having a higher film density than the high-temperature operating element film is formed in a predetermined shape on the other surface and the polished surface, a lead wire is joined to the resistor film, and the resistor film is further covered. Further, an insulating protective film is formed on the insulating member.

[Operation] Since the resistor film in the high-temperature operating element according to the present invention is a dense film formed on a polished surface by a thin film forming method, a pattern can be formed with high accuracy, and the resistor film is fused to the resistor film. The insulating protective film functions to prevent oxidation of the resistor film due to the use atmosphere and to suppress a change in resistance during use. At the same time, it acts to hold down the substrate and the film so as not to peel off during use. On the other hand, since the element side is porous, it is easy to fit in such that a protective layer, an electron emission aid coating layer, an insulating layer and the like are easily provided on the element according to the purpose.

Embodiment An embodiment of the present invention will be described below with reference to the drawings. FIG. 1 is a sectional view showing a high-temperature operating device according to an embodiment of the present invention. In the figure, (1) is a ceramic substrate (insulating substrate), (2) is a dense resistor film having a high film density for a heater, (3) is a vitreous protective coating layer (insulating protective film), (4) ) Is a porous film having a low film density for a high-temperature operation element film, and (5) is a lead wire.
For each material, for example, it is desirable to satisfy the following requirements. The substrate (1) has good thermal conductivity and a coefficient of thermal expansion close to that of the resistor film (2), is a good insulator, does not break down at high temperature,
Be smooth. Therefore, considering availability, AlN, Al ₂ O ₃
And so on. For the resistor film (2), the vapor pressure at a high temperature range is low, and the electrical characteristics at a high temperature range are stable. Therefore, Mo, W, Pt, Ta, TiN, TiC and the like are considered. For the protective coating layer (3), diffusion at high temperatures should be small, and the softening point or melting point should be higher than the operating temperature. Therefore, a stable soft glass having a high softening point and a high melting point such as SiO ₂ and Al ₂ O ₃ can be considered. For example, in the case of SiO ₂ , the softening point is 1710 ° C. (crystal) and the melting point is 1470 ° C. (crystal). In the case of Al ₂ O ₃ , the melting point is 2030 ° C. Further, a material that scatters outside during firing, such as CaO or V ₂ O ₃ , may be included. For the lead wire (5), it is most desirable to have the same characteristics as the resistor film (2), the same diffusion coefficient as the resistor film (2), and the same material as the resistor film (2). The element film (4) should be a porous film that is provided to improve its performance and is well compatible with a protective layer, an electron emission aid coating layer, an insulating layer, and the like.

With the above-mentioned material and the structure as shown in FIG. 1, a voltage is applied to the lead wire (5) to heat the heater, that is, the resistor film (2), and to back the element film (4). It is suitable for improving the performance of a high-temperature operating element that is operated after being warmed up. For example, if a high current density is to be obtained from the element film (4),
If an electron emission aid is applied on the element film (4), the resistance change is small even when used for a long time, it is stable as a heater, and is peeled off because it is covered with a glassy protective film. Further, since the element film is porous, the electron emission aid is well adapted and a high current density can be obtained.

Here, in consideration of the above conditions, W is applied on the substrate,
W / AlN is used as a W co-fired ceramic substrate obtained by simultaneously firing these, W is formed as a resistor film (2) by a sputtering method, and glass containing SiO ₂ as a main component is used as a vitreous protective coating layer (3). A method for manufacturing a high-temperature operating element coated with high quality "glaze" will be described. In addition,
Reference Photo 1 shows a surface photograph of the porous W fired substrate used in the example, and Reference Photo 2 shows a surface photograph of the dense W sputtered film (same magnification as Reference Photo 1).

After etching the W side of the W co-fired ceramic substrate (W / AlN substrate) into a pattern of a predetermined shape, the A side of the W / AlN substrate is etched.
lN side is mechanically polished and mirror-finished. This substrate (1)
A mask of a desired heater pattern is set thereon, and a W resistor film (2) having a desired thickness (several μm to 10 μm) is formed by a sputtering method. Next, the lead wire (5) is joined to a desired place by a method such as resistance welding. Next, a vitreous "glaze" is sprayed so as to cover the heater resistor film (2) and dried to form a coating layer (3). Next, it is baked for 5 to 10 minutes in a vacuum or in hydrogen or argon, and is fused to the W resistor film. The processing temperature at this time depends on the composition of the "glaze", but 800-1400 ℃
It is about. Here, "glaze" refers to a so-called vitreous solution of an oxide. For example,
Table 1 shows the compositions of three types of glazes, A, B, and C. This is one example of a commercially available glass type ceramic coating material. Table 2 shows the composition of what is called a frit in Table 1, which is a so-called glassy oxide. This vitreous material dissolves the metal oxide slightly generated in the resistor film (2) during use as a heater and fills the gap between the metals to act as a seal coat, so that the glass material adheres to the resistor film (2). The nature is also excellent. Also,
Since it is glassy, it has high electrical insulation and does not hinder its function as a high-temperature heater.

When a protective layer, an electron emission aid coating layer, an insulating layer, and the like are provided on the surface of the element film in the next process, since the sintered substrate is made of W particles, the above-described layer is easily absorbed by the porous material. .

During use at a high temperature, distortion may occur between the substrate (1), the resistor film (2), and the protective film (3) due to a difference in thermal expansion coefficient. It exhibits a flexible behavior such as filling and acts to alleviate distortion, so that even if the entire surface is covered, there is no problem with distortion.

Further, when the lead wire (5) is coated with the same vitreous material, the effect is further enhanced.

In addition, as shown in FIG. 2, processing can be performed over a large area of the ceramic substrate.

In the above embodiment, the method of applying “glaze” was described. However, a vitreous target is prepared and a vitreous protective coating layer (3 ) Can be formed.

With respect to the vitreous composition, a single composition such as SiO ₂ or Al ₂ O ₃ may be used instead of the composite composition shown in Table 2. For example, if the substrate (1) is Al ₂ O ₃ , coating the Al ₂ O ₃ protective layer (3) also has the advantage that it is not necessary to consider the influence of impurities and diffusion.

In the above embodiment, a co-fired substrate W / AlN was used, and W
Although an example in which a high-temperature operating element film having a predetermined shape is obtained by the above-described etching has been described, a W / AlN substrate on which an element pattern is screen-printed may be used. Alternatively, a high-temperature operating element film may be formed by etching a film formed by another method, for example, a method such as thermal spraying or cladding into a predetermined shape, as long as a porous surface is formed.

In the above embodiment, the method of forming the W resistor film (2) by the sputtering method has been described. However, the so-called P method such as electron beam evaporation, laser PVD, ion plating, etc.
Needless to say, it can be formed by a method such as a VD method or a CVD method using a WF ₆ , W (CO) ₆ , WCl ₆ gas or the like. The same applies to the case where a film other than W, such as Mo, is formed.

In addition, since the insulating substrate in the above embodiment was AlN which reacts with water or alkali, a wet process was not used for forming the heater pattern. However, a wet process may be used if the substrate is made of Al ₂ O ₃ or the like.

[Effects of the Invention] As described above, according to the present invention, a porous high-temperature operating element film having a low film density is formed in a predetermined shape on one surface of an insulating member. In a predetermined shape on the polished surface, a resistor film having a higher film density than the high-temperature operating element film is formed, a lead wire is bonded to the resistor film, and the resistor film is further covered. Since the high-temperature operating element is formed by forming the insulating protective film on the insulating member, the problem of separation between the film and the substrate is solved, and a high-temperature operating element with a long-term reliable high-temperature heater can be provided. It has the effect of. In addition, since the resistor film is formed on a polished surface with a dense film, a desired pattern can be formed with high accuracy. On the other hand, since the element film is a porous film having a low film density, the performance of the element is reduced. Therefore, there is an effect that conformity with a layer provided on the element is good and the performance of the element can be easily improved.

[Brief description of the drawings]

FIG. 1 is a sectional view showing a high-temperature operating device according to one embodiment of the present invention, FIG. 2 is a sectional view showing a high-temperature operating device according to another embodiment of the present invention, and FIG. Cross-sectional configuration diagram showing a conventional high-temperature operating element formed by utilizing
FIG. 4 is an explanatory view showing a conventional method for manufacturing a high-temperature operating element by a thin film forming method, and FIG. 5 is a curve diagram showing a change over time in a resistance value of the conventional high-temperature operating element. In the figure, (1) is an insulating substrate (ceramic substrate),
(2) is a resistor film, (3) is a protective coating layer,
(4) is an element film, and (5) is a lead wire. In the drawings, the same reference numerals indicate the same or corresponding parts.

Continuation of the front page (51) Int.Cl. ⁶ identification symbol FI H05B 3/20 328 H05B 3/20 328 (58) Field surveyed (Int.Cl. ⁶ , DB name) H01J 1/20 H01J 1/22 H01J 1/26 H01J 9/04-9/10 H05B 3/20 305-333

Claims (1)

(57) [Claims] 1. A porous high-temperature operating element film having a low film density formed on one surface of an insulating member and a predetermined shape on a polished surface of the other surface of the insulating member. A resistor film having a higher film density than the high-temperature operating element film, a lead wire bonded to the resistor film, and an insulating protective film formed on the insulating member to cover the resistor film. High temperature operating element.