JPH0528882B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Object of the Invention] (Industrial Application Field) The present invention relates to a thick film resistive element, and particularly to improving the material of an insulating coating layer covering a resistor layer thereof.

(Prior Art) Thick film resistive elements are used, for example, in applications such as being incorporated into an electron gun assembly such as a color picture tube and supplying a divided voltage to each electrode. An example of this is shown in Japanese Patent Application Laid-Open No. 14627/1983. The partial voltage resistance element built into the tube is made by printing and coating a resistance layer made of ruthenium oxide (RuO ₂ )-glass in a zigzag pattern on an insulating substrate made of alumina ceramics, baking this, and then applying this resistance layer. An insulating coating layer made of lead borosilicate glass is formed to cover the. This is then baked at 550-650°C for approximately 20-30 minutes. In addition, aluminum oxide is contained in the material of this insulating coating layer to suppress changes in resistance value, particularly due to high voltage knocking, in the manufacturing process of color picture tubes.

Incidentally, a condition required of this type of thick film resistive element is that the resistance value does not change much even when the temperature becomes high due to high temperature atmosphere or Joule heat generated during operation.

(Problems to be Solved by the Invention) However, when this type of conventionally known thick-film resistor element is incorporated into an electron tube and operated, approximately It is confirmed that there is a phenomenon in which the resistance value changes significantly within 200 to 300 hours. Further, this change in resistance value is particularly noticeable in areas to which high voltage is applied, resulting in an undesirable change in the voltage division ratio. When the resistance value partially changes in this way, the distribution of voltage supplied to each tube electrode changes and the electron lens action deteriorates, resulting in a deterioration in image quality in, for example, a color picture tube.

In view of the above circumstances, it is an object of the present invention to provide a thick film resistive element whose resistance value hardly changes even during long-term operation.

(Summary of the Invention) This invention provides an insulating coating layer mainly made of lead borosilicate glass that covers the resistor layer.
The thick film resistance element includes at least one transition metal oxide selected from chromium, cobalt, zinc, copper, zirconium, and cadmium.

(Function) According to such a thick film resistor element, even if it is operated for a long time under relatively high temperature or high voltage conditions, the change in the resistance value of the resistor layer can be kept within an extremely small range. can.

As will be described later, in the case of the conventional configuration, lead oxide, which is a common constituent of the resistor layer and the insulation coating layer, is eluted from the resistor layer and the insulation coating layer that covers it, and this causes the resistance value to decrease. It is thought that this is changing significantly. In contrast, according to the present invention, the insulating coating layer of the thick film resistance element essentially contains iron oxide, and nickel, chromium, cobalt, etc.
By containing at least one transition metal oxide selected from zinc, copper, zirconium, and cadmium, the elution of lead oxide from the resistor layer to the insulating coating layer is suppressed. Thereby, it is possible to obtain a thick film resistive element whose resistance value hardly changes even if it is operated for a long time at high temperature or in a high electric field. The reason for this is that the insulation coating layer contains iron oxide and other transition metal oxides, both of which are basic oxides, so the acidity of the insulation coating layer is kept low, and the oxidation in the resistor layer is suppressed. Lead (PbO)
There is little reaction of eluting into the insulating coating layer. In this way, changes in the resistance value of the resistor layer are suppressed.

(Example of the invention) Examples thereof will be described below with reference to the drawings.

FIG. 1 is a central vertical sectional view thereof, and FIG. 2 is a plan view seen through from above the insulating coating layer constituting the outer surface.

In accordance with a preferred manufacturing procedure, first, an elongated insulating substrate 27 made of ceramic containing approximately 96 weight percent aluminum oxide is prepared. The material of this insulating substrate may be a ceramic substrate containing aluminum oxide as a main component and silicon oxide, magnesium oxide, calcium oxide, etc., or a glass substrate. Low-resistance island-shaped electrode layers 28, 28... and stainless steel terminals 22, 23, 24, 2 including through pins are provided at required locations on this insulating substrate 27.
5, 26 are provided.

Next, on one surface of this insulating substrate 27, an inorganic mixture of ruthenium oxide (RuO ₂ ) powder and glassy material powder whose main components are lead oxide (PbO) and silicon oxide (SiO ₂ ) is melted and kneaded. The resulting resistive material is printed and coated in a zigzag pattern. This is electrically connected to each electrode terminal, and the resistor layer 29
becomes. The resistor layer 29 mainly contains ruthenium oxide, lead oxide, and silicon oxide, but may also contain titanium oxide, aluminum oxide, and bismuth oxide. In addition,
The low-resistance island-shaped electrode layer portions 28, 28, . to obtain a low resistance value.

Next, the insulating substrate coated with the resistor layer and the like is fired in the atmosphere at a temperature in the range of about 550 to 1000°C, for example 950°C. Then, the resistance value of the resistor layer is adjusted by laser trimming.

Next, to cover the resistor layer 29, lead borosilicate glass materials, namely 10 weight percent boron oxide (BeO ₃ ), 27 weight percent silicon oxide (SiO ₂ ),
Insulation containing 55% by weight lead oxide (PbO), 5% by weight aluminum oxide (A ₂ O ₃ ), and 3% by weight iron oxide (calculated as added as Fe ₂ O ₃ ) The material for the covering layer 30 is made into a paste and applied by thick film printing. Note that each terminal is not coated and left exposed.

This is then fired in air at a temperature in the range of about 550-1000°C, for example 600°C. This is then further heated at a temperature in the range of 400-550°C _{lower than} the previous firing temperature, e.g. Heat treatment for an hour.

Note that the insulating coating layer 30 may be heat-treated at a temperature of 550 to 1000° C. in a hydrogen atmosphere after coating. Through such heat treatment, a glassy insulating coating layer 30 is obtained.

Through the above manufacturing process, a thick film resistive element with a total resistance value of 500 MΩ was obtained.

The material of the insulating coating layer 30 that covers the resistor layer and the insulating substrate surface is mainly lead borosilicate glass, with iron oxide, nickel, chromium,
Contains at least one transition metal oxide selected from cobalt, zinc, copper, zirconium, and cadmium. Among these, it is particularly desirable to make iron oxide essential. and iron oxide from 0.5 to 10
weight percent (calculated as added as Fe ₂ O ₃ ), more preferably 2-5% by weight
Contain.

The thick film resistance element 21 obtained in this way is
It is arranged along the electron gun structure of the color picture tube and electrically connects the electron lens electrode and the terminal. According to the thick film resistive element of the present invention, it has been confirmed that the resistance value of the resistor layer hardly changes even during long-term operation. In other words, the resistance value of the resistor layer will not change even if the element goes through a relatively high temperature state, becomes high temperature due to Joule heat generated in the resistor layer itself, or is operated for a long time under conditions where a high voltage is applied. I was able to keep it within a very small range.

The reason why the present invention allows the change in resistance value of the resistor layer to be kept within an extremely small range even when operated at high temperature and high electric field for a long time will be explained below.

The present inventors have investigated the causes of this resistance value fluctuation,
We devised the relationship between the properties of various oxides contained in glass. As a result, in conventional thick-film resistor elements with an insulating coating layer made mainly of lead borosilicate glass, a reaction occurs in which lead oxide (PbO) in the resistor layer is leached into the insulating coating layer, resulting in a resistance to resistance. It can be inferred that the value is changing. In other words, although the conventional insulating coating layer made of lead borosilicate glass contains basic lead oxide (PbO), it has a high acidity due to the strongly acidic silicon oxide (SiO ₂ ) and boron oxide (B ₂ O ₃ ). is very high. If this insulating coating layer is simply placed on the resistor layer, the reaction between the two layers will not proceed. However, when the temperature of both layers rises due to Joule heat while the resistor element is in use, a reaction occurs in which lead oxide (PbO) in the resistor layer is leached into the insulation coating layer in a direction that neutralizes the acidity of the insulation coating layer. . It is thought that this changes the resistance value of the resistor layer.

In contrast, the resistor element according to the present invention has an insulating coating layer made of basic oxides such as iron oxide, nickel oxide, chromium oxide, cobalt oxide, zinc oxide, copper oxide, zirconium oxide, and cadmium oxide. Since the structure includes a transition metal oxide, the acidity of the insulating coating layer is kept low. Therefore, even if the temperature rises during use of the resistor element, the reaction between both layers, that is, the elution of lead oxide (PbO) from the resistor layer to the insulating coating layer, is suppressed, and changes in resistance value are suppressed. .

In particular, the iron oxide contained in the insulation coating layer is
It coexists as divalent and trivalent (ie, FeO and Fe ₂ O ₃ ). All of these are basic oxides, but divalent iron (Fe ²⁺ ) has a higher basicity, so
This reduces the reaction in which lead oxide (PbO) in the resistor layer dissolves into the insulating coating layer, thereby suppressing changes in resistance value. Therefore, it is more desirable that 90% or more of the iron in the iron oxide be divalent iron (Fe ²⁺ ).

Based on this reasoning, we attempted to demonstrate the results. The state of each insulating coating layer of a resistance element having an insulating coating layer containing iron oxide in various states was analyzed. In other words, before a resistive element is built into the picture tube, the distribution of constituent elements in the cross section of each insulating coating layer is measured using an electron beam excited X-ray microanalyzer (EPMA).
Analyzed by. The equipment used was manufactured by JEOL.
High-speed wide-area multi-analyzer JCMA-733 manufactured by Co., Ltd.
This is a special EPMA that has the function of displaying the element distribution as the concentration distribution of that element. Each resistive element was then assembled into a picture tube and operated at an anode voltage of 30 kV for approximately 3,000 hours. They were then classified into approximately three ranks depending on the degree of change in resistance value after 3000 hours with respect to the intended resistance value, and the change in resistance value corresponded to the state analysis of the insulating coating layer before operation. . As a result, the iron L-line spectrum shown in A in Figure 3 was confirmed before operation.
The amount of change in resistance value was about 4%, and the resistance value showed a tendency to change particularly significantly around 200 to 300 hours. This measurement was carried out at an accelerating voltage of 10 KeV using the L-ray of iron, where the effects of changes in chemical bonds are sensitive to wavelength and shape. Also, the same figure B
In the case shown in Fig. 2, the change in resistance value is about 2%. Furthermore, the one indicated by C in the same figure shows almost no change in resistance value even after being operated for about 3000 hours. For comparison, FIG. 3 shows the iron L-line spectra of FeO and Fe ₂ O ₃ used as standard samples.

A comparison of the analyzes shown in Figure 3 shows that in state A, FeO (Fe ²⁺ ) and Fe ₂ O ₃ (Fe ³⁺ ) coexist, and in state B, Fe ² It can be seen that although the coexistence of ⁺ and Fe ³⁺ is observed, the amount existing as Fe ³⁺ is decreasing, and that the C state has become a single state of only Fe ²⁺ . Therefore,
In order to keep the change in resistance value even smaller,
It can be seen that it is desirable for the iron oxide in the insulating coating layer to be in a single state of only Fe ²⁺ from the beginning.

The inventors also calculated the total resistance value of the thick film resistance element.
500MΩ, and make various resistor elements that are the same except that the insulating coating layer contains iron oxide or not, install these in the picture tube, and apply a voltage of 300kv, which is the anode voltage of the picture tube, between both terminals. agreement
The device was operated for 3000 hours and the amount of change in total resistance value was examined.
Figure 4 shows the iron oxide content (Fe ₂ O ₃
Calculated as added as (weight ratio)
The relationship between this and the amount of change in resistance value with respect to the initial resistance value after 3000 hours of operation is shown below. As is clear from the results in FIG. 4, when the amount of iron oxide in the insulating coating layer is in the range of 0.5 to 10 weight percent,
Especially when in the range of 2 to 5 weight percent,
Changes in resistance value during long-term operation can be suppressed to a value so small that it does not pose a practical problem.

In addition, at least 90%, more preferably 95%, of the iron ions forming iron oxide contained in the insulating coating layer
It is desirable that the above is Fe ²⁺ . That is,
When approximately 90% of the iron ions forming the iron oxide contained in the insulating coating layer are Fe ²⁺ , curve Q ₁ is shown in Figure 5.
As shown in Figure 3, after approximately 3000 hours of operation, the change in resistance value could be kept to about 2%. Similarly
In the case where 95% is Fe ²⁺ , as shown by curve Q ₂ in the same figure, it is about 1%, and similarly, 100% is Fe ²⁺
As shown by curve _Q3 in the figure, the change in resistance value could be kept to a negligible level from the beginning of operation.

In this way, more than 90% of the iron ions that form iron oxide contained in the insulation coating layer are absorbed from the initial stage of operation.
To make it Fe ²⁺ , the insulating coating layer contains 0.5 to 100 weight percent iron oxide (calculated assuming that it is added in the form of Fe ₂ O ₃ ) as described above.
If it contains hydrogen, it can be reliably obtained by performing heat treatment in an atmosphere containing at least hydrogen.

〔Effect of the invention〕

As explained above, according to the present invention, the elution of lead oxide from the resistor layer constituting the thick film resistor element to the insulating coating layer is suppressed, and the element can be operated for a long time at relatively high temperatures or under high electric fields. However, the change in resistance value can be kept within a small range. A highly reliable thick film resistance element can be obtained.

[Brief explanation of the drawing]

FIG. 1 is a sectional view of a main part showing an embodiment of the present invention.
Figure 2 is a plan view, Figure 3 is a state comparison diagram, Figure 4
5 and 5 are characteristic comparison diagrams, respectively. 21 ... Thick film resistance element, 22-26... Terminal, 27
...Insulating substrate, 29...Resistor layer, 30...Insulating coating layer.

Claims (1)

[Claims] 1. A resistor layer made of an inorganic mixture containing ruthenium oxide, lead oxide, and silicon oxide as main components is deposited on an insulating substrate, and lead borosilicate glass is applied to cover this resistor layer. In a thick film resistance element provided with an insulating coating layer mainly composed of iron oxide and at least one transition selected from nickel, chromium, cobalt, zinc, copper, zirconium, and cadmium, A thick film resistance element comprising a metal oxide. 2. The thick film resistance element according to claim 1, wherein the insulating coating layer contains iron oxide in a range of 0.5 to 10% by weight of the entire coating layer. 3 In the insulation coating layer, more than 90% of the iron in the iron oxide is 2
The thick film resistive element according to claim 1 or 2, which is made of valent iron (Fe ²⁺ ).