JPH02253601A - Metal oxide film resistor of three-layer structure - Google Patents

Abstract

PURPOSE:To increase resistance and reduce resistance change rate due to exposure to high temperature and that due to solder heat resistance by forming a first metal oxide film layer on the surface of an insulating base and then forming specific second and third metal oxide film layers on it. CONSTITUTION:The title item consists of a first metal oxide film 2 directly in contact with the surface of an insulating base 1, a second metal oxide film 3 with a small resistivity less which is coated on the first metal oxide film 2, and a third metal oxide film 4 with less specific resistance than the first metal oxide film and with a resistivity different from that of the second metal oxide film. Then, since the first metal oxide film 2 is a layer which was further crystallized, there are recesses and projections on the surface and the second and third metal oxide films 3 and 4 are thinly formed on them, thus resulting in a large resistance, small resistance change rate due to solder heat resistance, and small resistance change due to exposure to high temperature.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a metal oxide film resistor in which a metal oxide film containing tin oxide as a main component is formed on an insulating substrate.

[Prior Art] A conventionally known metal oxide film resistor has a structure in which, for example, a metal oxide film containing tin oxide as a main component is formed on the surface of a rod-shaped porcelain substrate (for example, 3 m in diameter and 11 mm in length). Metal cap terminals are fitted onto both ends of the coated rod-shaped porcelain base to form connection terminals, and after attaching lead wires, these surfaces are coated with an insulating and moisture-resistant material. Covered with an exterior protective film.

Generally, metal oxide film resistors with a small resistance temperature coefficient are used, which are made by forming a metal oxide film containing antimony in a tin oxide film whose main component is tin oxide. There is.

Such metal oxide film resistors are generally manufactured by forming a metal oxide film on the surface of an insulating substrate by a method called "spraying method."

In the method called "spraying", tin chloride (SnCβ) is first added to a mixed solution of water, hydrochloric acid, alcohol, etc.
A raw material solution in which 4) and a small amount of antimony trichloride (sb cβ, ) are dissolved and a rod-shaped mullite/corundum porcelain substrate are prepared.

Next, separately from this, using these raw material solutions and the porcelain substrate, using a membrane device whose main part is shown in FIG.
A metal oxide film resistor is manufactured by forming a metal oxide film on the surface of the substrate.

To explain the outline of the membrane device shown in Fig. 3, a heat-resistant Fi9 is rotatably supported in a class 8, and a heating element is provided on the furnace wall so that the entire cage is heated. . There is a raw material solution supply device outside the furnace! 0 and a device fff11 for compressing air are provided. Pipe 12 from raw material solution supply device lO and air compressor +1 toward n9, respectively.
．． 13 have been derived. A nozzle 14 is connected to the leading end of the pipe and is installed so that the raw material solution is sprayed toward the basket.

For film deposition using this device, the raw material solution is supplied to the raw material solution supply device! Put the mullite/corundum porcelain a into the 15R9 and while rotating, raise the temperature inside the furnace to 500.
The temperature is raised to 800°C to 800°C, and in this state, the raw material solution is sprayed from a nozzle using compressed air. After that, the spraying is stopped, the heating inside the furnace is stopped, and the substrate is taken out.The resistor taken out from the furnace is placed in another furnace and heated to 200℃.
It is heat treated at a temperature of ~300° C. for several 10 minutes to several hours to form a thermally and electrically stable film.

Next, metal caps are fitted on both ends of the base, and the surface of the base is cut in a spiral shape to obtain a predetermined resistance value. After that, the lead wires were welded and a protective film was formed to obtain a metal oxide film resistor product. However, due to problems such as stability and reliability of the film, a resistance value of only about 200Ω before spiral cutting could be obtained. In addition, the temperature coefficient of resistance has only been achieved to about ±200 ppm/''C in the temperature range of -55°C to +155°C.

[Problems to be Solved by the Invention] Obtaining a higher resistance value than the conventional resistance value without spiral cutting by using a metal oxide film formed on the surface of a substrate having the above dimensions requires increasing the film thickness. This is possible by making it thinner and increasing the resistance value. however,
As the film thickness becomes thinner and the resistance value increases, other characteristics change. For example, soldering due to an increase in the temperature coefficient of resistance and a decrease in thermal stability is caused by the rate of change in resistance value before and after and due to high temperature storage. There is a problem in that a practically usable high resistance metal oxide film resistor cannot be obtained because of an increase in the rate of change in resistance value. In addition, since slight variations in film formation conditions have a large effect on the temperature coefficient of resistance of metal oxide film IIQ resistors, it is difficult to obtain metal oxide film resistors with a small temperature coefficient of resistance, especially ±110.
There was a problem in that it was not possible to obtain a metal oxide resistor with a value within 0 pp/''C.

An object of the present invention is to provide an inexpensive metal oxide film resistor that solves these problems.

[Means for Solving the Problem] As a means for solving the problem, the present inventors formed a metal oxide film consisting of a laminate of two different layers containing tin oxide as a main component on the surface of an insulating substrate. We have developed a product that is a further improvement of Fuzo's composite metal oxide film resistor, which has connection terminals attached to both ends of the 10-layer insulating substrate. In this improved product, the metal oxide film portion is composed of a laminate of three different layers, and the first metal oxide film layer is formed on the surface of the insulating substrate, and the first layer has a specific resistance. This can be obtained by forming a second metal oxide film layer with a small resistance, and further forming a third metal oxide film layer having a specific resistance smaller than the first layer and different from that of the second layer. This is a three-layer metal oxide film resistor.

The first metal oxide film is made of iron, indium, nickel,
The main component may be a thin film of tin oxide, which contains as an auxiliary component at least an element selected from the group consisting of phosphorus, zinc, cadmium, and antimony, and its thickness is preferably 0.05 to 5 μm, preferably 0. It can be made into .5-2μ seaweed.

The second metal oxide film has at least l! 4
The thin film may be made of tin oxide as the main component, and may have a thickness of 0.003 to 2 .mu.m, preferably 0.005 to 1 .mu.m.

The third metal oxide film contains at least l a selected from the group consisting of antimony, nickel, chromium, fluorine, phosphorus, arsenic, iron, manganese, barium, bismuth, cobalt, zinc, copper, boron, cadmium, and vanadium.
The main component containing the element i as an auxiliary component can be a thin film of tin oxide, and the thickness thereof can be 0.003 to 2 μm, preferably 0.005 to 1 μm.

[Function] Since the first metal oxide film formed on the surface of the insulating substrate according to the present invention is a relatively thick layer, crystallization progresses, and the crystal diameter grows large. The second metal oxide film is a layer formed on the crystal plane of the first metal oxide film, so although it is a thin film, fine crystal grains are not precipitated and the crystallinity is high. It is made of a good, thermally stable membrane.

The third metal oxide film is a layer formed by crystal growth on the crystal plane of the second metal oxide film, so that it overlaps with the crystal plane of the second metal oxide film, so although it is a thin metal oxide film, no microcrystals are precipitated and it has a crystalline property. The film is thermally stable.

Since the first metal oxide film is a highly crystallized layer, its surface is uneven, and the second and third metal oxide films are both thinly formed on top of it, increasing the resistance value. It is a film that has been coated.

Furthermore, since the temperature coefficient of resistance of the metal oxide film resistor of the present invention is a composite value of the temperature coefficients of resistance of the second and third metal oxide films, ±100 ppn +
/ ” temperature coefficient of resistance within 1°C is possible.

Therefore, even if the thickness of the second and third metal oxide films with low specific resistance, which govern the resistance value of the resistor, is made thinner, the resistance value is high and the rate of change in resistance value due to soldering heat resistance is small, and the resistor has a high resistivity value. It becomes possible to obtain a resistor that has a small rate of change in resistance value due to the change in resistance value, and a resistance temperature coefficient that is extremely small compared to conventional ones.

Next, the configuration of the present invention will be explained in detail based on examples.

[Example 1] Mullite corundum with an alumina content of 70%! A
100 pieces of porcelain base (diameter 3.0no+, length flam)
00 pieces were prepared, ultrasonically cleaned in alcohol for 1 minute, then in pure water for 15 minutes, and dried in a dry mold at a temperature of 170° C. for 60 minutes.

Also, apart from this, pure water ・・・・・・１２
50g ethyl alcohol・・・・・・・・・・・・・・・
・ Prepare 70 g of a mixed solution, and add to the mixed solution: 625 g of an aqueous solution containing 60% tin chloride (Sn Cβ4) and iron chloride (FeCJ!s'6Hio) ** +84
．． A first raw material solution was prepared by dissolving 6 g.

Next, pure water ・・・ ・・・ ・・・ 125
0g hydrochloric acid...
200g ethyl alcohol・・・・・・・・・・・・
Prepare 70 g of a mixed solution, and add to the mixed solution 525 g of an aqueous solution containing 50% tin chloride (SnCβ4) and 7% tin chloride (SbCJ2s). 25.7g
A second raw material solution was prepared by dissolving.

Next, pure water・・・・・・・・・・・・・・・・・・
・1250g hydrochloric acid
200g ethyl alcohol・・・・・・・・・・・・
Prepare 70 g of a mixed solution, and add to the mixed solution 625 g of an aqueous solution containing 6 liters of stannic chloride (SnCI; ts) and 7 nitimony chloride (SbCRs). A third raw material solution was prepared by dissolving 31.5 g.

After preparing these raw material solutions, the surface porcelain substrate was placed in the basket of the film deposition apparatus whose main parts are shown in Fig. 3, and the temperature inside the furnace was raised to 700''C while rotating the basket. ,700℃
The first raw material solution is put into the raw material solution supply device 1o while maintaining the same temperature, and a mist of the raw material solution is sprayed together with compressed air from the nozzle 14. After that, the second JJx raw material solution is sprayed, and then the second raw material solution is sprayed. After spraying the raw material solution No. 3, the temperature inside the furnace is lowered while the spraying is stopped and the basket is continued to rotate, and the Mi device body coated with the film is taken out and the film thickness is
As a result, the thickness of the first metal oxide film is 1 μm on average, and the thickness of the second metal oxide film is:
The average thickness of the metal oxide film of the third rri was 5XIO-'μm.

Next, the resistor was heat-treated at 200° C. for 2 hours in a separately prepared furnace, and then metal caps with lead wires were fitted to both ends of the base, and the surface of the base other than the lead wires was covered. A resistor was obtained which was coated with a protective film and packaged with an insulating material.

Four groups of 200 resistors were randomly selected from these resistors, and the resistance value at 20°C, resistance temperature coefficient, resistance change rate due to soldering heat resistance, and resistance value change rate due to high temperature storage were calculated. was measured for all 200 pieces in each group according to the four-terminal method.

The resistance value at 20°C is determined by leaving the resistor in a constant temperature bath kept at a temperature of 20"C for 30 minutes, and then changing the resistance value (R,.) at 20"C. The average flI was determined, rounded to the nearest IO, and shown in Table 1.

The rate of change in resistance value before and after soldering heat resistance was determined by measuring the resistance value at 20°C, then immersing the resistor in a solder bath melted at 350°C for 3 seconds, taking it out, and leaving it at room temperature for 3 hours. Thereafter, the resistance value was measured, and the rate of change with respect to the resistance value at 20° C. was determined, and the maximum absolute value of the rate of change is shown in Table 1.

To measure the resistance temperature coefficient, leave the resistor in a constant temperature bath kept at 20°C for 30 minutes, and then change the resistance value (R,.) at 20°C to iJl'! Then, the temperature in the constant temperature bath was maintained at -55℃, held for 30 minutes, and then the resistance value was measured.Then, the temperature was raised to 155℃, and after held for 30 minutes, the resistance value was measured at the temperature of 155℃. Measured at 20℃
Difference in resistance value between and 155℃, 20℃ and -55℃ (ΔR)
was calculated, and the resistance fA frequency was calculated using the following formula.

Northern bamboo snoring (ΔR/R, 0-ΔTl・10'(ppm/
``C) However, △T indicates the difference between 2(1'c) and rRQ constant 4 degrees.

In this way, the temperature coefficients of resistance on the low temperature side and high temperature side of the 200 resistors were determined, and the maximum absolute values of the temperature coefficients of resistance are shown in Table 1.

The rate of change in resistance value when left at high temperature is as follows: After measuring the resistance value at 20"C, leave it in a zoo"C constant temperature bath for 100 hours, take it out, and let it return to room temperature for 12 minutes. The resistance value was measured, and the rate of change with respect to the resistance (+6) of 20''C was determined, and the maximum absolute value of the rate of change is shown in Table 1.

[Example 2] In the second and third raw material solutions in Example 1, 25.7 g of chloride (Sb CAs),
Ammonium fluoride (NH, F1
Example 1: Chiongai with added 21.4g and 32.0g
The same treatments and measurements as above were carried out, and the results shown in Table 1 were obtained.

[Example 3] (Hereinafter blank) Antimony chloride (S b CQ s) 25.7 g and 31 g were added to the second and third raw material solutions in Example 1.
．． Nickel chloride (NiCgx・6H,0
) The treatment and measurement were carried out in the same manner as in Example 1, except that 5.8 g and 8.6 g were added, respectively, and the results shown in Table 1 were obtained.

[Example 4] 25.7 g and 31.5 g of antimony chloride (SbCβs) in the second and third raw material solutions in Example 1
Chromium chloride (CrClS-6HsO)7
．． The treatment and measurement were carried out in the same manner as in Example 1, except that 2 g and 8 g were added, respectively, and the results shown in Table 1 were obtained.

[Example 5] Processed in the same manner as in Example 1 except that 10.7 g and 13.4 g of ammonium fluoride (NH, F) were further added to the second and third raw material solutions in Example 1, respectively. The results shown in Table 1 were obtained.

[Examples 6 to 8] In the first raw material solution in Example 1, the amount of iron chloride (Fe C s-6Ht O) was set to 42.3 g, and nickel chloride (NiO2, . 6
Hz O) 29.5g, Phosphorus pentachloride (PC flood,)
25.4g, indium chloride (In Cl2s'nHx
o, where n=3 to 4) The treatment and measurement were performed in the same manner as in Example 1, except that 51.0 g was added, and the results shown in Table 1 were obtained.

[Examples 9 and 101 The average film thicknesses of the second and third metal oxide films in Example 1 were 3X 10-'μm and 5X10-'', respectively.
The processing and measurements were carried out in the same manner as in Example 1, except that the thickness was set to μm, and the data shown in Table 1 was obtained.

[Example 11.12] The treatment and measurement were carried out in the same manner as in Example 1, except that the average thickness of the first metal oxide film in Example 1 was set to 0.5 μm and 2.0 μm, respectively. , the results shown in Table 1 were obtained.

[Comparative Example 1] A second metal oxide film was immediately formed without forming the first metal oxide film in Example 1! The treatment and measurement were carried out in the same manner as in Example 1, except that the thickness of the second and third metal oxide films was 5XlO-''μm.
What are the results shown in Table 1? 4.

(Left below) Example 1~! In 2, the case where the raw material contained in the first raw material solution mainly contains tin chloride and contains iron, iron and nickel, iron and phosphorus, iron and indium is shown, but the embodiment of the present invention The same effect is not limited to these cases, but a similar effect can be obtained when any element of lf1 or more selected from iron, indium, nickel, phosphorus, zinc, cadmium, and antimony is included. Any IF where the additive element is selected from iron, indium, nickel, and phosphorus! Particularly good effects can be obtained when the above conditions are met.

Further, although an example has been shown in which the raw material contained in the second raw material solution is mainly composed of tin chloride and contains antimony, fluorine, nickel, chromium, antimony and fluorine, the present invention is not limited to these cases. , chromium, fluorine,
Any one selected from phosphorus, arsenic, iron, manganese, barium, bismuth, cobalt, zinc, copper, boron, cadmium, and vanadium! ! Similar effects can be obtained when the above elements are included. Particularly effective is when one or more of antimony, nickel and chromium is selected.

Further, although an example has been shown in which the raw material contained in the third raw material solution is mainly composed of tin chloride and contains antimony, fluorine, nickel, chromium, antimony and fluorine, the present invention is not limited to these cases. , nickel, chromium, fluorine, phosphorus, arsenic, iron, manganese, barium, bismuth,
Any lf selected from cobalt, zinc, 14, boron, cadmium, vanadium! Similar effects can be obtained when the above elements are included. Particularly effective is when one or more of antimony, nickel and chromium is selected.

Further, in Examples 1-12, only the case where the additive elements contained in the second and third raw material solutions are the same is shown, but the same effect can be obtained even when the additive elements are different.

Further, in Examples 1-12, only the case where the second and third metal oxide films have the same thickness is shown, but the same effect can be obtained even when the thicknesses are different.

Furthermore, although a cylindrical porcelain substrate was used in Examples 1 to 12, the shape of the substrate is not limited to this, and any shape, such as a prismatic or plate-like shape, will exhibit the same effect.

In addition, in Examples 1 to 2 above, the film was deposited by "spraying method", but ultrasonic! Lii! The same effect can be obtained by making the raw material solution fine enough to float using a tlJ powder, making it into a gaseous state, and spraying it onto the substrate, or by depositing a film by CVD, sputtering, or the like.

[Effects of the Invention] According to the present invention, it is possible to increase the resistance value of a conventional metal oxide film resistor by several tens of times, and the resistance value change rate due to high temperature storage and resistance value change due to soldering heat resistance is reduced. A metal oxide film resistor with a high thermal stability and a small coefficient etc. can be obtained.
Furthermore, a metal oxide film resistor with an unprecedentedly low temperature coefficient of resistance can be obtained. Therefore, the present invention greatly contributes to expanding the scope of use and improving reliability of metal oxide film resistors in the electronic industry.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a sectional view of a metal oxide film resistor of the present invention, and FIG. 2 is a perspective view thereof. FIG. 3 is a schematic view, including a cross-sectional view, of an example of a film deposition apparatus used for manufacturing the metal oxide film resistor of the present invention. Symbol Explanation l...Insulating base 2...First metal oxide film 3...Second metal oxide film 4...Third oxide Metal film 5...Cap 6...Lead 7
...Exterior protection v4 8...Furnace 9...
... Basket lO ... Raw material solution supply device II.
...A device that compresses air

Claims (2)

[Claims] (1) A metal oxide film resistor having a structure including a metal oxide film containing tin oxide as a main component on the surface of an insulating base, wherein the metal oxide film is in direct contact with the surface of the insulating base.
a second metal oxide film coated on the first metal oxide film and having a lower specific resistance than the first metal oxide film, and further on the second metal oxide film. The metal oxide film is coated with a three-layered metal oxide film consisting of a third metal oxide film having a resistivity lower than that of the first metal oxide film and a resistivity different from that of the second metal oxide film. A three-layer metal oxide film resistor. (2) The first metal oxide film has a thickness of tin oxide as a main component containing at least one element selected from the group consisting of iron, indium, nickel, phosphorus, zinc, cadmium, and antimony as an auxiliary component. The second metal oxide film is a thin film of 0.05 to 5 μm, and the second metal oxide film contains antimony, nickel, chromium, fluorine, phosphorus, arsenic, iron, manganese, barium, bismuth, cobalt, zinc, copper, boron, cadmium, and vanadium. The main component is a thin film of tin oxide with a thickness of 0.003 to 2 μm, and the third metal oxide film contains antimony, nickel, chromium, The thickness of the main component is tin oxide, which contains as an auxiliary component at least one element selected from the group consisting of fluorine, phosphorus, arsenic, iron, manganese, barium, bismuth, cobalt, zinc, copper, boron, cadmium, and vanadium. The three-layer metal oxide film resistor according to claim 1, which is a thin film of 0.003 to 2 μm.