JP3266752B2 - Metal oxide film resistor - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a metal oxide film resistor widely used for forming circuits of various electric appliances.

[0002]

2. Description of the Related Art As shown in FIG. 5, a metal oxide film resistor generally comprises a rod-shaped insulating substrate 1 such as mullite or alumina, and tin oxide or antimony-added tin oxide (ATO) formed on the surface thereof. Metal oxide film 10, metal cap terminals 5 and 6 pressed into both ends of the base material, lead wires 7 and 8 welded to the terminals, and protective film 9 formed on the surface of the resistor It is composed of When the metal oxide film material is composed of a tin oxide single phase, the specific resistance is large and the temperature coefficient of resistance (TCR) is very large. For this reason, generally, as a metal oxide film material, AT
O has been put to practical use.

The method of manufacturing the above metal oxide film resistor generally uses a chemical film forming method such as a spray method or a chemical vapor deposition method (CVD). In these methods, 60
The vapor of an aqueous solution or an organic solvent solution containing stannic chloride and antimony trichloride is sprayed onto the rod-shaped substrate 1 in a furnace heated to 0 to 800 ° C., so that the ATO film ( A metal oxide film 10) is formed. Further, the metal cap terminals 5 and 6 are press-fitted into both ends of the substrate 1,
While rotating the substrate 1 so as to obtain a desired resistance value, AT
A part of the O film is trimmed with a diamond cutter or a laser, and after the lead wires 7 and 8 are welded to the cap terminals 5 and 6, a protective film 9 made of resin is formed.
Obtain a metal oxide film resistor. The completed resistance value of the metal oxide film resistor obtained in this manner varies depending on the thickness of the ATO film and the number of trimming turns, if the size of the base material is constant, but is generally from 10Ω to 100 kΩ.

[0004]

According to the above-described resistance adjusting method, in order to obtain a metal oxide film resistor having a completed resistance value of 100 kΩ or more, the thickness of the ATO film must be reduced or the ATO film must be thinned. It is necessary to take a method of narrowing the trimming interval of. However, since the specific resistance of the ATO film is approximately 1 × 10 ⁻³ to 1 × 10 ⁻² Ω · cm, the film thickness must be considerably reduced in order to increase the resistance value. At this time, since the strain of the film itself and the ratio of the depletion layer on the film surface to the entire film increase, there is a problem that the TCR tends to be a large negative value.

Further, when the initial resistance value of the ATO film is low, if the final resistance value is set to 100 kΩ or more, the number of turns of trimming by a laser or the like increases, and it takes a very long time for trimming. Is too narrow, and there is also a problem that it cannot be physically trimmed. And, as described above, if the film thickness is made too thin or the trimming interval is made narrower,
As the cross-sectional area of the electric conduction path decreases, the contact area with the outside increases, and the resistance value of the film itself changes due to the influence of moisture and alkali ions in the insulating base material due to electric stress and humidity. Therefore, it was difficult to obtain a metal oxide film resistor having high reliability. An object of the present invention is to provide a highly reliable metal oxide film resistor having a completed resistance value of 100 kΩ or more, a low temperature coefficient of resistance, and a high reliability.

[0006] Metal oxide film resistor of the present invention, Murai
, Alumina, cordierite, forsterite and
Base material made of a material selected from the group consisting of iron and steatite, at least one selected from the group consisting of tin oxide, indium oxide, and zinc oxide provided on the base material. A resistive film composed of a metal oxide thin film as a main component, and an insulating film composed of a metal oxide thin film that suppresses diffusion of alkali ions into the resistive film provided between the insulating substrate and the resistive film Comprising, the insulating film is silicon oxide, aluminum oxide, titanium oxide,
And at least one selected from the group consisting of zirconium oxide . Also book
The invention relates to the resistance film provided on the resistance film.
A second insulator made of a metal oxide thin film that suppresses intrusion of moisture
Further comprising an edge film, wherein the second insulating film is made of silicon oxide, acid,
Aluminum oxide, titanium oxide, and zirconium oxide
At least one selected from the group consisting of
A metal oxide film resistor.

Here, the metal oxide thin film on the substrate
The film thickness of the composed insulation coating, it is not preferable is smaller than the surface roughness of the substrate.

[0008]

[Function] By forming a metal oxide insulating film between an insulating base material and a metal oxide resistance film, a factor of a decrease in reliability due to the thinning of the metal oxide film for higher resistance. Can be suppressed from being diffused. In addition, by forming a thin metal oxide insulating film on the metal oxide resistance film, water content, which is another factor in reducing reliability due to the thinning of the metal oxide film for higher resistance, is used. The deterioration of the resistance film due to the above can be suppressed. At this time, by making the film thickness of the metal oxide insulating film thinner than the surface roughness (Ra) of the base material,
The contact between the metal oxide resistance film and the cap terminal becomes possible, and a special means for electrically connecting the two is not required. By forming these metal oxide insulating films, it is possible to suppress a decrease in reliability due to an increase in resistance, and to obtain a metal oxide film resistor having high resistance and high reliability.

[0009]

FIG. 1 shows a metal oxide film resistor according to an embodiment of the present invention. An insulating base material 1, a metal oxide insulating film 2 formed on the base material 1, a metal oxide resistance film 3 formed on the insulating film 2, a metal cap terminal pressed into both ends of the base material 5, 6, a lead wire 7 welded to the terminal,
8 and a protective film 9 formed on the surface of the resistor. Here, the substrate 1 only needs to have an insulating property at least on the surface, and is preferably made of mullite, alumina, cordierite, forsterite, or steatite . The insulating film 2 suppresses diffusion of alkali ions into the resistance film 3, and is made of silicon oxide, aluminum oxide, titanium oxide, or zirconium oxide.
It is preferable that the main component is nickel . Further, the resistance film 3 is preferably made of a material having high electric conductivity and a high carrier concentration and mainly composed of tin oxide, indium oxide or zinc oxide. Also, the cap terminals 5 and 6 only need to be ohmically joined to the resistance film 3, and the lead wires 7 and 8 only need to be ohmically joined to the cap terminals 5 and 6.

FIG. 2 shows a metal oxide film resistor according to a reference example . 1 in that a metal oxide resistance film 3 is formed on an insulating substrate 1 and a metal oxide insulation film 4 is formed thereon. Here, the insulating film 4 suppresses deterioration of the resistance film 3 due to moisture or the like, and the same material as the insulating film in FIG. 1 is used. Figure 3
5 shows a metal oxide film resistor according to another embodiment. A metal oxide insulating film 2, a metal oxide resistance film 3,
The point that the metal oxide insulating film 4 is sequentially formed is different from the above example. Note that the sizes in FIGS. 1 to 3 are not always accurate. In particular, in FIGS. 2 and 3, the cap terminals 5 and 6 are not shown to be in contact with the resistance film 3, but the surface of the substrate 1 is rough and the film 4 formed on the surface is rough. Is thin film, etc.
The cap terminal press-fitted on the coating 4 partially cuts the coating 4 and is in electrical contact with the resistance coating 3.

FIG. 4 shows the surface of a heated insulating substrate,
1 shows an apparatus for forming a metal oxide film by supplying vapor or mist of a composition for forming an insulating film or a resistance film made of a metal oxide. A quartz reaction tube 11 containing a base material on which a metal oxide is to be formed is fixed by a packing 13 in a furnace core tube 12 also made of quartz. The furnace core tube 12 inserted into the electric furnace 14 is driven by a driving device (not shown) to be rotated at an appropriate rotation speed in the electric furnace 14. A raw material supply device 16 containing the metal oxide film forming composition 15 is connected to a gas supply device 17 for supplying a carrier gas by a pipe 18, and the reaction tube 1 is connected by a pipe 19.
Connected to 1. Also, at the other end of the reaction tube 11,
An exhaust device 21 is connected by a pipe 20.

In order to form a metal oxide film on the surface of a substrate using this apparatus, first, the substrate is placed in a reaction tube 11 and set as shown in the drawing, and the substrate is heated by an electric furnace 14.
While maintaining the temperature at which the composition for forming a metal oxide film is thermally decomposed or higher, the reaction tube 11 is rotated. In this state, the carrier gas is sent from the gas supply device 17 to the raw material supply device 16 through the pipe 18, and the vapor or mist of the metal oxide film forming composition is supplied to the reaction tube 11 through the pipe 19. The vapor or mist supplied to the reaction tube 11 is decomposed in contact with the base material to form a metal oxide film on the base material surface. Then, the undecomposed metal oxide film forming composition is sucked by the gas exhaust device 21, cooled, and collected. In addition, as the carrier gas supplied from the gas supply device 17, air, oxygen, or an inert gas such as nitrogen or argon is used. The supply amount of the evaporation or mist can be controlled by the flow rate of the carrier gas. Further, by heating the raw material supply device 16 or applying ultrasonic waves to the raw material supply device, the supply amount of the evaporation or mist can be controlled.
The rotation of the reaction tube 11 is for uniformly forming the metal oxide film on the substrate, and mechanical vibration may be applied instead of rotating the reaction tube 11. In addition, there is no particular need to rotate the furnace core tube 12, and in this embodiment, the reactor tube 11 is fixed to the furnace core tube 12 in order to stabilize the rotation.

Example 1 In this example, a metal oxide film resistor having the structure shown in FIG. 1 was manufactured. First, a composition for forming the metal oxide insulating film 2 and a composition for forming the metal oxide resistance film 3 were synthesized as follows. In a 200 ml Erlenmeyer flask, 10 ml of silicon tetraethoxide (Si (OCH ₂ CH ₃ ) ₄ ) was weighed, and 40 ml of methanol was added and dissolved to synthesize a composition for forming an insulating film. Further, Erlenmeyer flask 200 ml, stannic chloride _{5g (SnCl 4 · 5H 2 O} )
And the number of moles of metal M, and the formula M / (Sn +
M) having a value of 0.09 of antimony trichloride (Sb
Cl ₃ ) was weighed, and 68 ml of methanol and 8 ml of concentrated hydrochloric acid were added and dissolved to synthesize a composition for forming a resistive film. Next, using the apparatus shown in FIG. 4, a cylindrical substrate 1 having an alumina content of 92% (outer diameter 2 mm, length 10 mm, surface roughness R
a 0.3 μm), a metal oxide insulating film and a metal oxide resistance film were sequentially formed. That is, first, the base material 1 was placed in the reaction tube 11 and the composition for forming an insulating film was placed in the raw material supply device 16. Air was used as the carrier gas, the gas flow rate was 1 liter / min, and the heating temperature of the substrate 1 was 800 ° C. The heating temperature of the substrate is
The heating temperature may be lower than the deformation temperature of the base material or the melting point of the insulating film to be formed, and the higher the heating temperature, the better the quality of the obtained insulating film. 80
The substrate 1 in the reaction tube 11 was held at 0 ° C. for 30 minutes, and then 7 g of the composition for forming an insulating film was fed into the reaction tube 11 over 30 minutes to form the insulating film 2 on the substrate surface. It was kept at 800 ° C. for 10 minutes. The film thickness of the insulating film 2 thus formed is usually several tens to several thousand nm, but in this embodiment, it was about 300 nm.

Next, in the same manner, the substrate 1 on which the insulating film 2 was formed was placed in a reaction tube 11 and the composition for forming a resistive film was placed in a raw material feeder 16. Air was used as the carrier gas, the gas flow rate was 1 liter / min, and the heating temperature of the substrate 1 was 800 ° C. The heating temperature in this case may be lower than the deformation temperature of the base material 1 or the melting point of the resistance film 3 formed with the insulating film 2. The higher the heating temperature, the better the quality of the resistance film 3 obtained. Yes, 400-9
00 ° C is preferred. The substrate 1 in the reaction tube 11 was held at 800 ° C. for 30 minutes, and then 1.2 g of the composition for forming a resistive film was formed.
Was sent into the reaction tube 11 over 7 minutes to form the resistive film 3 and then kept at 800 ° C. for 10 minutes. The film thickness of the resistance film 3 formed in this manner is usually several tens to several thousands n
m, but in this example, it was about 200 nm. The tin-plated stainless steel cap terminals 5 and 6 are press-fitted into both ends of the substrate 1 on which the insulating film 2 and the resistance film 3 are formed, and trimmed for 8 turns with a diamond cutter. Copper lead wires 7, 8 plated with tin on 5, 6 were welded. Finally, a thermosetting resin paste is applied to the surface of the resistive film 3 and dried, and heated at 150 ° C. for 10 minutes to form an insulating protective film 9.
Was formed to obtain a metal oxide film resistor of the present invention. The protective film 9 only needs to have insulation properties and moisture resistance.
As the material, only a resin or a material containing an inorganic filler is used. For curing the protective film, light such as visible light or ultraviolet light may be used instead of heat.

Reference Example 2 g of aluminum chloride (AlCl ₃ ) was weighed into a 200 ml Erlenmeyer flask, and 75 ml of methanol was added and dissolved to synthesize a composition for forming a metal oxide insulating film. After holding the substrate put in the reaction tube 11 at 800 ° C. for 30 minutes using the apparatus of FIG.
2.5 g of the same composition for forming a resistive film as in Example 1 placed in the raw material supplier 16 was fed into the reaction tube 11 at a flow rate of air of a carrier gas of 1 liter / min for 15 minutes, and the resistive surface The film 3 was formed and further kept at 800 ° C. for 10 minutes. The resistance film thus obtained has a thickness of about 40.
It was 0 nm. Next, the substrate 1 on which the resistance film 3 is formed
Is placed in a reaction tube and kept at 800 ° C. for 30 minutes, and then 1 g of the above-mentioned composition for forming an insulating film placed in the raw material feeder 16
Was fed into the reaction tube 11 at a flow rate of carrier gas air of 1 liter / min over 5 minutes to form an insulating film 4 on the surface of the resistive film 3 and further kept at 800 ° C. for 10 minutes.
The film thickness of the insulating film 4 thus formed is about 50 n.
m. Thus, a metal oxide film resistor having the configuration shown in FIG. 2 was produced.

Example 2 10 ml of titanium tetraisopropoxide (Ti (OCH (CH ₃ ) CH ₃ ) ₄ ) was placed in a 200 ml Erlenmeyer flask.
Was weighed and dissolved by adding 40 ml of methanol to synthesize a composition for forming a metal oxide insulating film. Using the apparatus of FIG. 4, the substrate 1 on which the insulating film 2 and the resistance film 3 were sequentially formed in the same manner as in Example 1 was placed in a reaction tube 11, and 800 ° C.
After holding for 30 minutes, 4 g of the above-mentioned composition for forming an insulating film put in the raw material supplier 16 is sent into the reaction tube 11 at a flow rate of carrier gas air of 1 liter / min for 20 minutes, and the surface of the resistive film is formed. An insulating film is formed on the
C. for 10 minutes. The thickness of the insulating film 4 thus formed was about 100 nm. Thus, a metal oxide film resistor having the configuration shown in FIG. 3 was produced.

Comparative Example 1 A resistor was manufactured in the same manner as in Reference Example except that the metal oxide insulating film 4 was not formed. Comparative Example 2 A resistor was produced in the same manner as in Comparative Example 1 except that 1 g of the metal oxide film forming composition was sent into a reaction tube over 5 minutes, and the thickness of the resistance film 3 was changed to about 100 nm. .

Table 1 shows a comparison of the characteristics of the resistors of Examples 1 and 2, Reference Example and Comparative Examples 1 and 2. Each resistance value is about twice that before trimming. The rate of change is at a temperature of 60 ° C and a relative humidity of 95%.
This is the rate of change of the resistance value after standing for 100 hours with respect to the value before standing. The temperature coefficient of resistance (TCR) is 25
It is a value at 125C to 125C.

[0019]

[Table 1]

[0020]

As described above, according to the present invention, a metal oxide film resistor having a small temperature coefficient of resistance can be obtained even in a high resistance value region.

[Brief description of the drawings]

FIG. 1 is a longitudinal sectional view showing a schematic configuration of a metal oxide film resistor according to an embodiment of the present invention.

FIG. 2 is a longitudinal sectional view showing a schematic configuration of a metal oxide film resistor in a reference example .

FIG. 3 is a longitudinal sectional view showing a schematic configuration of a metal oxide film resistor according to another embodiment of the present invention.

FIG. 4 is a longitudinal sectional view showing a schematic configuration of an apparatus for producing a metal oxide film in one embodiment of the present invention.

FIG. 5 is a longitudinal sectional view showing a schematic configuration of a conventional metal oxide film resistor.

Continued on the front page (72) Inventor Masaki Ikeda 1006 Kazuma Kadoma, Osaka Prefecture Inside Matsushita Electric Industrial Co., Ltd. Inventor Yasuhiro Shindo 1006 Kazuma Kadoma, Kadoma, Osaka Prefecture Inside Matsushita Electric Industrial Co., Ltd. (72) Inventor Kozo Igarashi 1006 Kadoma Kadoma, Kadoma City, Osaka Pref. 64-37894 (JP, A) JP-A-1-130502 (JP, A) JP-A-2-256201 (JP, A) JP-A-1-137502 (JP, U)

Claims (2)

(57) [Claims] (1) mullite, alumina, cordierite,
Select from the group consisting of forsterite and steatite
An insulating substrate made of a selected material, and a resistor made of a metal oxide thin film containing at least one selected from the group consisting of tin oxide, indium oxide, and zinc oxide provided on the substrate. A film, and an insulating film made of a metal oxide thin film that suppresses diffusion of alkali ions into the resistance film provided between the insulating substrate and the resistance film, wherein the insulating film is silicon oxide; A metal oxide film resistor comprising, as a main component, at least one selected from the group consisting of aluminum oxide, titanium oxide, and zirconium oxide. 2. The resistance skin provided on the resistance film.
The first layer consisting of a metal oxide thin film that suppresses the penetration of moisture into the film
A second insulating film, wherein the second insulating film is made of silicon oxide.
Element, aluminum oxide, titanium oxide, and zirconium oxide
At least one element selected from the group consisting of
The metal oxide film resistor according to claim 1, wherein