JP3259884B2 - 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 which is widely used, for example, when constructing circuits for various electric appliances.

[0002]

2. Description of the Related Art Conventionally, as shown in FIG. 5, a metal oxide film resistor has 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 cap terminals 5 and 6 pressed into both ends of the base material, lead wires 7 and 8 welded to the terminals, and a protective film 9 formed on the surface of the resistor. It is composed of

On the other hand, considering a material that can be used as a metal oxide film material, a tin oxide single phase has a large specific resistance and a temperature coefficient of resistance (hereinafter, referred to as TCR) is very large. The conditions of use are very limited and not practical.

[0004] For these reasons, ATO having a small specific resistance and a TCR having a positive value or a value close to 0 has been put to practical use as a metal oxide film material. These materials have a high TCR since the carrier concentration is high and the effect of scattering of the carrier by the lattice vibration is larger than the increase of the carrier concentration by the heat excitation energy when the temperature rises. High electrical conductivity.

[0005] As described above, in general, those having a low specific resistance have a high carrier concentration and a positive or nearly zero TCR.
Those having a large specific resistance have a low carrier concentration,
TCR has a large negative value.

[0006] As a method of manufacturing the above-described metal oxide film resistor, a chemical film forming method such as a spray method or a chemical vapor deposition method (CVD) is generally used. In these methods, a rod-shaped mullite-alumina-based substrate 1 is sprayed with a vapor of an aqueous solution or an organic solution containing stannic chloride and antimony trichloride in a furnace heated to 600 to 800 ° C. , ATO film (metal oxide film 1)
0) is formed. Further, metal cap terminals 5 and 6 are press-fitted into both ends of the base material 1 so that the base material 1 has a desired resistance value.
Is rotated, and a part of the ATO film is trimmed with a diamond cutter or laser.
After welding the lead wires 7 and 8 to 6, a protective film 9 made of resin is formed to obtain a metal oxide film resistor. The completed resistance value of the metal oxide film resistor obtained in this way depends on the thickness of the ATO film and the number of trimming turns, if the size of the base material is constant, and is generally 10Ω to 100Ω.
kΩ.

[0007]

According to such a conventional 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. A method of narrowing the trimming interval of the ATO film can be considered.

However, in the case of a conventional metal oxide film resistor, the specific resistance of the ATO film is about 1 × 10 ^-3 to 1
Since it is × 10 ^-2 Ω · cm, the film thickness must be considerably reduced in order to increase the resistance value. At this time, there is a problem that the TCR tends to be a large negative value because the strain of the film itself and the ratio of the depletion layer on the film surface to the entire film increase.

Further, when the initial resistance value of the ATO film is low, if the final resistance value is 100 kΩ or more, the number of turns of the trimming by the laser increases, so that the trimming takes a very long time and the trimming interval is too narrow. Therefore, there is also a problem that the trimming cannot be performed physically.

[0010] As described above, when the film thickness is too thin or the trimming interval is narrowed, the cross-sectional area of the electric conduction path decreases, and the contact area with the outside increases. As a result, the resistance value of the film itself changes due to the influence of moisture and alkali ions in the insulating base material, and it has been difficult to obtain a highly reliable metal oxide film resistor.

The present invention solves such a problem of a conventional metal oxide film resistor, and has a completed resistance value of 100 k.
It is an object of the present invention to provide a metal oxide film resistor having a TCR of not less than Ω, a TCR smaller than that of the related art, and a higher reliability.

[0012]

The present invention of claim 1 Means for Solving the Problems] includes at least an insulating substrate, a metal oxide film having a negative temperature coefficient of the resistance value on the substrate, on the film positive A metal oxide film resistor comprising a metal oxide film having a temperature coefficient of resistance and a metal oxide film having a temperature coefficient of negative resistance on the film having the temperature coefficient of positive resistance. is there.

According to a second aspect of the present invention, there is provided a metal oxide film resistor in which the metal oxide film contains tin oxide, indium oxide, or zinc oxide as a main component.

According to the first aspect of the present invention, for example, an insulating base material and a metal oxide film having a positive temperature coefficient of resistance are mainly used as a resistor, and a metal oxide film having a positive temperature coefficient of resistance is used between the base material and the film. Forming a metal oxide film having a negative temperature coefficient of resistance, and further forming a metal oxide film having a temperature coefficient of negative resistance on the metal oxide film having a temperature coefficient of positive resistance. Thereby, it is possible to suppress the diffusion of alkali ions, which is a cause of the decrease in reliability due to the thinning for higher resistance, and to suppress the deterioration of the film having a positive temperature coefficient of resistance due to moisture. .

The formation of the metal oxide film having a negative temperature coefficient of resistance makes it possible to suppress a decrease in reliability due to an increase in resistance.
A highly reliable metal oxide film resistor can be obtained.

[0022]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Embodiments of the metal oxide film resistor according to the present invention will be described below with reference to the drawings.

First, prior to the description of a specific embodiment, the metal oxide film manufacturing apparatus used in the present embodiment will be described with reference to FIG.

As shown in FIG. 1, the substrate 1 is placed in a reaction tube 11, and the reaction tube 11 is fixed so as to be located at the center of a furnace core tube 12 of an electric furnace 13. The core tube 12 is rotated. At this time, the furnace core tube 12, the reaction tube 11, and the substrate 1 are heated by the electric furnace 13 to a temperature at which the composition for forming the metal oxide film (10) is decomposed or higher.

The rotation of the reaction tube 11 is for uniformly forming the metal oxide film 10 on the substrate 1, and mechanical vibration may be applied to the reaction tube 11. Furnace core tube 12
It is not particularly necessary to rotate the reaction tube.
Is fixed to the furnace core tube 12 in order to stabilize the rotation.

Into the reaction tube 11, a carrier gas 18 is fed from a gas supply device 17 through a pipe 15 to a raw material supply device 16 containing the film forming composition, and a gas of the film forming composition is supplied through a pipe 14. Or send a mist. The sent gas or mist is decomposed on the heated substrate 1 to form a metal oxide film 10. The undecomposed gas of the film forming composition is sucked by the gas exhaust device 20, cooled, and collected.

The carrier gas 18 supplied from the gas supply device 17 includes an inert gas such as air, oxygen, nitrogen and argon. It is possible to control the supply amount of mist and mist. Also, by heating the raw material supply device 16 or applying ultrasonic waves to the raw material supply device 16, it is also possible to control the supply amount of the gas or mist of the film forming composition.

(Reference Example 1) FIG. 1 shows a metal oxide film resistor of one reference example related to the present invention . Next, the configuration of this embodiment will be described with reference to FIG.

As shown in the figure, the metal oxide film resistor according to the present embodiment comprises an insulating substrate 1, a metal oxide film 2 having a negative TCR formed on the substrate 1, Metal oxide film 3 having a positive TCR formed on film 2
And metal cap terminals 5 and 6 pressed into both ends of the base material, and lead wires 7 and 8 welded to the terminals.
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 its surface, and is preferably made of porcelain such as mullite, alumina, cordierite, forsterite, and steatite. The coating 2 is a metal oxide coating material that suppresses diffusion of alkali ions into the coating 3, has a lower electrical conductivity than the coating 3, and has a negative TCR. Those containing tin oxide, indium oxide, and zinc oxide as main components are preferable. Further, the coating 3
May be a material having a positive TCR, high electrical conductivity and a high carrier concentration, and is preferably a material containing tin oxide, indium oxide, and zinc oxide as main components.

The composition for forming the metal oxide film (2) and the composition for forming the metal oxide film (3) were synthesized as follows.

In a 200 ml Erlenmeyer flask, 5 g of stannic chloride (Chemical formula 1) and 10 mol% of silicon tetraethoxide (Chemical formula 2) according to (Formula 1) are weighed and dissolved by adding 75 mL of methanol. The composition for forming the film (2) was synthesized. Also, in a 200 ml Erlenmeyer flask, 5 g of stannic chloride (chemical formula 1) and 3 mol% of antimony trichloride (chemical formula 3) in (formula 1) were weighed, and 68 ml of methanol and 8
ml of concentrated hydrochloric acid was added and dissolved to synthesize the composition for forming the film (3).

SnCl ₄ .5H ₂ O (Chemical formula 1) Si (OCH ₂ CH ₃ ) ₄ (Chemical formula 2) SbCl ₃ (Chemical formula 3) M / (Sn + M) × 100 (Formula 1) Using a device, a columnar substrate 1 of 92% alumina (outside diameter 2 mmφ × 10 mmL, Ra 0.3 μm) was placed in a reaction tube, and the film (2) forming composition was placed in a raw material supply unit 16. Air was used as the carrier gas 18, 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 1 may be lower than the deformation temperature of the substrate 1 or the melting point of the film 2, and the higher the heating temperature is, the better the film quality of the film 2 is obtained. Is preferred.

The substrate 1 in the reaction tube 11 was held at 800 ° C. for 30 minutes, and 3 g of the film (2) forming composition was placed in the reaction tube 11 for 20 minutes.
Minutes, and after forming the film 2, further at 800 ° C. for 10 minutes.
Hold for minutes. The thickness of the film 2 thus formed is usually several tens to several thousand nm, but in this embodiment, it is about 250 nm.
m.

Similarly, the substrate 1 on which the insulating film 2 has been formed is placed in a reaction tube using the film producing apparatus.
(3) The forming composition was placed in the raw material supply device 16. Air was used as the carrier gas 18, 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 1 may be lower than the deformation temperature of the substrate 1 or the melting point of the film 2 and the film 3, and the higher the heating temperature, the better the film quality of the film 3 is. 400-900 ° C is preferred.

The substrate 1 in the reaction tube 11 was held at 800 ° C. for 30 minutes, and 1 g of the composition for forming the film (3) was placed in the reaction tube 11 for 5 minutes.
Minutes, and after forming the resistance film 3, further 800 ° C
For 10 minutes. The thickness of the resistance film 3 thus formed is usually several tens to several thousand nm, but in this embodiment, it was about 150 nm.

The tin-plated stainless steel cap terminals 5 and 6 are press-fitted into both ends of the substrate 1 on which the film 2 and the film 3 are formed, and trimming is performed for 8 turns with a diamond cutter. Tin-plated copper lead wires 7, 8 were welded to the terminals 5, 6. In addition,
The cap terminals 5 and 6 only need to be in ohmic contact with the resistance film 3, and the lead wires 7 and 8 only need to be in ohmic contact with the cap terminals 5 and 6.

Finally, a thermosetting resin paste is applied and dried on the surface of the film 3 and heated at 150 ° C. for 10 minutes to form an insulating protective film 9. An oxide film resistor was obtained. The protective film 9 only needs to have insulation and moisture resistance, and may be made of a material containing only a resin or an inorganic filler as a material, and may be cured using light such as visible light or ultraviolet light in addition to heat. Good.

Reference Example 2 FIG. 2 shows a metal oxide film resistor according to a reference example relating to the present invention . Next, the configuration of this embodiment will be described with reference to FIG.

As shown in the figure, the metal oxide film resistor according to the present embodiment includes an insulating substrate 1, a metal oxide film 3 having a positive TCR formed on the substrate 1, Metal oxide film 4 having a negative TCR formed on film 3
And metal cap terminals 5 and 6 pressed into both ends of the base material, and lead wires 7 and 8 welded to the terminals.
And a protective film 9 formed on the surface of the resistor.

Here, the film 4 is for suppressing deterioration of the film 3 due to moisture, and is a metal oxide film material having a lower electric conductivity than the film 3 and a negative TCR. Often, those containing tin oxide, indium oxide, and zinc oxide as main components are preferable.

In a 200 ml Erlenmeyer flask, 5 g of stannic chloride (formula 1), 9 mol% of antimony trichloride (formula 1), and 10 mol% of ferric chloride (formula 1) (Formula 4) was weighed, and 68 ml of methanol and 8 ml of concentrated hydrochloric acid were added and dissolved to synthesize the composition for forming the film (4).

FeCl ₃ (Formula 4) The composition for forming the film (3) was fed into the reaction tube 11 for 10 minutes by using the film manufacturing apparatus to form the resistance film 3.
In this embodiment, the thickness of the resistance film 3 was about 300 nm.

Similarly, the substrate 1 on which the resistance film 3 is formed is placed in a reaction tube using the film production apparatus.
(4) The forming composition was placed in the raw material supplier 16. Air was used as the carrier gas 18, 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 1 may be lower than the deformation temperature of the substrate 1 or the melting point of the film 3 and the film 4, and the higher the heating temperature is, the better the film quality of the film 3 is. 400-900 ° C is preferred.

The substrate 1 in the reaction tube 11 was kept at 800 ° C. for 30 minutes, and 2.4 g of the composition for forming a film (4) was placed in the reaction tube 11.
After sending for 5 minutes and forming the film 4, the film was further heated at 800 ° C for 10 minutes.
Hold for minutes. The film thickness of the film 4 thus formed is usually several tens to several thousands nm, but in this reference example, it is about 100 nm.
m. Others are the same as the reference example 1 .

(Embodiment) FIG. 3 shows a metal oxide film resistor according to an embodiment of the present invention. Next, the configuration of this embodiment will be described with reference to FIG.

As shown in the figure, the metal oxide film resistor of this embodiment comprises an insulating substrate 1, a metal oxide film 2 having a negative TCR formed on the substrate 1, Metal oxide film 3 having a positive TCR formed on film 2
A metal oxide film 4 having a negative TCR formed on the film 3; metal cap terminals 5 and 6 pressed into both ends of the substrate; and a lead wire 7 welded to the terminal. And 8 and a protective film 9 formed on the surface of the resistor.

In a 200 ml Erlenmeyer flask, 5 g of stannic chloride (Formula 1), 9 mol% of antimony trichloride (Formula 3), and 10 mol% of chromium trichloride (Formula 1) Chemical formula 5) is weighed, and 68 ml of methanol and 8 ml
Was added and dissolved to obtain the composition for forming the film (4).

CrCl ₃ .6H ₂ O (Chemical Formula 5) Using the film production apparatus shown in FIG. 4, put the film 2 and the substrate 1 on which the film 3 is formed in a reaction tube 11 and prepare 1.8 g of the film. (4) The composition for formation was fed into the reaction tube 11 for 10 minutes to form the film 4 and then kept at 800 ° C. for 10 minutes. In this embodiment, the thickness of the coating 4 was about 100 nm. Others are the same as the reference example 1 .

(Comparative Example 1) For comparison, a resistor in which only the metal oxide film 3 was formed without forming the metal oxide film 4 among the two types of metal oxide films in Reference Example 2 was used. It was created as Comparative Example 1. Other configurations are the same as those of the second embodiment .

[0051] (Comparative Example 2) In addition, specifically that created the resistor for comparison as Comparative Example 2, the reaction tube 1 of a metal oxide film forming composition of 0.5g
Sent for three minutes during one. In this example, the thickness of the film 3 is about 80 nm.
Met. Others are the same as Comparative Example 1.

Table 1 shows Reference Examples 1 and 2, Examples, and Comparative Examples.
The results of 1 and 2 are given. The rate of change is 60 ° C, 95% RH
Is the rate of change in resistance when a 100-hour moisture resistance test is performed.

[0053]

[Table 1]

As shown in the above (Table 1), Comparative Example 1
The performance as a conventional resistor is shown in that the completed resistance value is 100 kΩ or less. In Comparative Example 2, the finished resistance value was certainly increased by making the film thickness about one-fourth thinner than Comparative Example 1, but as can be seen from the results of the change rate. This indicates that it is low in reliability that is susceptible to aging.

On the other hand, each of the reference examples 1 and 2 and the embodiment has a high resistance with a completed resistance value of 100 kΩ or more, a small TCR, and a highly reliable metal oxide. It can be said that it is a film resistor. In particular, the embodiment is a metal oxide film resistor having the highest resistance and the highest reliability.

As described above, according to this embodiment, it is possible to provide a metal oxide film resistor having a wide range of resistance and a small TCR, and is suitable for use as a circuit resistor for consumer and industrial equipment. Things .

[0057]

[0058]

As is apparent from the above description, the present invention has a high resistance and has a much higher TCR than the conventional one.
Has the advantages of being small and having higher reliability.

[Brief description of the drawings]

[1] Ichisan metal oxide film resistors associated with the present invention
It is a schematic diagram showing a Reference Example.

FIG. 2 is a schematic view showing one reference example of a metal oxide film resistor related to the present invention.

FIG. 3 is a schematic view showing one embodiment of the metal oxide film resistor of the present invention.

FIG. 4 is a schematic view showing one embodiment of a metal oxide film manufacturing apparatus of the present invention.

FIG. 5 is a schematic view showing an example of a conventional metal oxide film resistor.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Base material 2, 4 Metal oxide film having a negative TCR 3 Metal oxide film having a positive TCR 5, 6 Cap terminal 7, 8 Lead wire 9 Protective film 10 Metal oxide film 11 Reaction tube 12 Furnace tube 13 Electric furnace 14, 15 Pipe 16 Raw material feeder 17 Gas supply device 18 Carrier gas 19 Pipe 20 Exhaust device 21 Base material 22 Metal oxide film 23 Cap terminal 24 Lead wire 25 Protective film

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. 2-256201 (JP, A) JP-A-1-291401 (JP, A)

Claims (2)

(57) [Claims] At least an insulating substrate, a metal oxide film having a temperature coefficient of negative resistance on the substrate, and a metal oxide film having a temperature coefficient of positive resistance on the film. , and a metal oxide film having a negative temperature coefficient of the resistance value on the film having a temperature coefficient of the positive resistance value
Metal oxide film resistor was. Wherein said metal oxide film is, claims mainly tin oxide, indium oxide, any of zinc oxide
2. The metal oxide film resistor according to 1.