JP5503132B2 - Resistor paste and resistor - Google Patents

Description

  The present invention relates to a resistor paste and a resistor manufactured using the resistor paste.

  Resistors for current detection are used in electronic circuits and power supply circuits of various electronic devices. As electric and electronic devices become smaller and more functional, there is an increasing need for thick film chip resistors that are formed by printing resistor paste on a heat-resistant substrate such as ceramic and firing it. ing. The characteristics required for such a current detection resistor are a low resistance value and a low TCR (Temperature Coefficient of Resistance).

  In order to realize such characteristics, Patent Document 1 proposes a resistor paste containing conductive metal powder made of mixed powder of copper powder and nickel powder or Cu-Ni alloy powder. A resistor manufactured using this resistor paste has a resistivity of 100 μΩ · cm or less and a TCR of ± 100 ppm / ° C. or less. However, the resistor mainly composed of copper and nickel has a large thermoelectromotive force with respect to copper used for electrodes and circuit wiring, and is, for example, 40 μV / ° C. or more in the compounding ratio of copper and nickel to obtain a low TCR. There is a problem that an error may occur in current detection due to the influence.

  On the other hand, as a resistor material suitable for a current detection resistor having a resistivity of 100 μΩ · cm or less, a TCR of ± 100 ppm / ° C. or less, and a thermoelectromotive force of about 2 μV / ° C., copper / manganese / A copper / manganese / aluminum alloy called nickel alloy or nickel-free manganin is known (Non-Patent Document 1).

  However, manufacturing a chip resistor from an alloy is complicated, expensive, and difficult to downsize. Therefore, Patent Document 2 and Patent Document 3 propose a resistor paste made of a metal powder having the same composition ratio as these alloys, a glass powder, and an organic vehicle. The resistance film produced by applying and baking the resistor paste of Patent Document 2 or Patent Document 3 on a ceramic substrate has a TCR of 100 ppm / ° C. or less, a resistivity of 200 μmΩ · cm or less, and a thermoelectric power against copper. 2 μV / ° C. or less.

However, there is a problem that the resistivity of the resistance film obtained by firing the resistor pastes of Patent Document 2 and Patent Document 3 is higher than that formed of the same kind of alloy and is insufficient as a low resistance material. Further, according to the applicant's follow-up test, there is a problem that it is difficult to obtain a resistor having good performance such as poor sintering of the resistive film after firing and low adhesion between the resistive film and the substrate. . Furthermore, glass powder has a problem that it is difficult to obtain a stable resistance value characteristic because the diffusion behavior in the metal component and the sintered particle interface differs depending on the firing conditions.
Japanese Patent Laid-Open No. 11-288801 JP 2005-353620 A International Publication WO2004 / 055836 Ohmsha, University Course, Electrical and Electronic Materials, S44 (1969) 2.20, p272, co-authored by Hiraichiro Hirai and 5 others

  The present invention has been made in view of the above points, and can maintain high adhesion and high resistance value stability while maintaining the low resistivity, low TCR, and low thermoelectromotive force of the copper-manganese system. It aims at providing a body paste and a resistor.

The resistor paste according to the present invention is a paste containing at least copper and manganese as a conductive metal powder, and the total amount of the conductive metal powder is 100 parts by mass, and the manganese is 8 to 30 parts by mass, As inorganic bonding agent, any of lead borosilicate glass, zinc borosilicate glass, calcium borosilicate glass, barium calcium borosilicate glass, bismuth borosilicate glass, magnesium borosilicate glass, or silica glass The glass powder and copper oxide powder which consist of these are substantially not included.

  Thus, by not including an inorganic bonding agent such as glass powder in the paste, the sintering-inhibiting elements of manganese are eliminated, and the melting point of manganese is lowered by the alloying of manganese with copper. Thus, it is possible to obtain a resistance film having a low electrical resistivity, a low TCR, a low thermoelectromotive force, and a stable resistance characteristic comparable to a pure alloy. Moreover, high adhesion to the substrate can be obtained by the diffusion of components at the interface between the resistance film and the ceramic substrate due to improved wettability to the substrate and the promotion of reaction, and the physical anchor effect. .

In the present invention, the conductive metal powder is a mixture of two or more types of conductive metal powders having different center particle sizes, and the conductive metal powder has a center particle size of 0.8 μm or less with respect to the total amount of the mixture. Is contained in an amount of 5% by mass or more and 40% by mass or less.

  By defining the particle size and content ratio of the conductive metal powder in this way, the contact area between the conductive metal powder and between the conductive metal powder and the substrate is increased, and good resistor performance can be obtained. At the same time, the adhesion to the substrate can be further improved.

  The present invention is further characterized by further containing at least one conductive metal powder selected from nickel, iron, and aluminum.

  By adding these nickel, iron, and aluminum to a copper-manganese system, the TCR can be further reduced while maintaining a low resistance value.

Moreover, in this invention, when the total amount of the said electroconductive metal powder is 100 mass parts, the said copper is 70-90 mass parts, It is characterized by the above-mentioned.

  By setting the content ratio of the conductive metal powder in this way, all of the low TCR, the low resistance value, and the low thermoelectromotive force can be achieved more reliably.

A resistor according to the present invention is characterized in that a resistor film is formed by applying the resistor paste to the surface of an insulating substrate and firing the resistor paste, and has a low resistivity and a low TCR. Thus, it is possible to obtain a resistor having a resistance film having a low thermoelectromotive force and having high adhesion and resistance value stability.
Further, the present invention is characterized in that the volume resistivity of the resistive film after being applied and baked is 20 to 200 μΩ · cm.

  When the resistivity is within this range, a low resistance resistor of 50 mΩ or less, further 10 mΩ or less can be easily obtained, and the resistivity within this range can be obtained by using the resistor paste of the present invention. Can be easily obtained.

  According to the present invention, the absence of an inorganic bonding agent such as glass powder in the paste eliminates manganese sintering-inhibiting elements, and the alloying of manganese with copper lowers the melting point and causes firing. As a result, it is possible to obtain a resistance film having a low electrical resistivity, a low TCR, a low thermoelectromotive force, and a stable resistance value comparable to those of a pure alloy. Moreover, high adhesion to the substrate can be obtained by the mutual diffusion of the components between the paste and the substrate due to the improvement of the wettability to the substrate, the promotion of the reaction, and the physical anchor effect. A resistor having a resistance film having a low resistivity, a low TCR, a low thermoelectromotive force, and having high adhesion and resistance value stability can be obtained.

  Hereinafter, the best mode for carrying out the present invention will be described.

  The resistor paste of the present invention contains at least copper and manganese as the conductive metal powder. The copper-manganese alloy, particularly the manganin alloy has a low resistivity, a low TCR, and a low thermoelectromotive force as known in the aforementioned Non-Patent Document 1, and this is also the case with the resistor paste of the present invention. By containing copper and manganese as the conductive metal powder, a resistor having a low resistivity, a low TCR, and a low thermoelectromotive force can be formed.

  As this electroconductive metal powder, it is also possible to use metals other than copper and manganese, for example, nickel, iron, aluminum, etc. can be used. In addition to selecting one type from nickel, iron, aluminum, etc., a plurality of types can be selected and added. Thus, by using nickel, iron, and aluminum in addition to copper and manganese as the conductive metal powder, the TCR can be reduced while maintaining a low resistance value. Of nickel, iron, and aluminum, nickel is most preferable.

  The particle size of the conductive metal powder is not particularly limited, but when the paste is screen-printed, the range of 0.1 to 20 μm is preferable because it is suitable for printing.

  Moreover, it is preferable to contain the fine electroconductive metal powder whose center particle diameter is 0.8 micrometer or less 5 to 40 mass% of the whole amount of electroconductive metal powder. The particle size of the fine conductive metal powder is more preferably 0.5 μm or less. Here, the central particle diameter is a value measured using a laser diffraction / scattering particle size distribution meter.

  When the center particle size and content ratio of the conductive metal powder are within such a range, the paste is applied to the surface of the substrate and fired to produce a resistance film. The contact area between the metal powder and the substrate is increased, and alloying is promoted to obtain a resistance film having good resistor performance, and the resistance film adheres due to the chemical reaction with the substrate and the anchor effect on the substrate. The power can be greatly improved. If the content of the fine conductive metal powder having a center particle size of 0.8 μm or less exceeds 40% by mass, the viscosity of the paste becomes high and the applicability such as printing may be deteriorated. The lower limit of the center particle size is not particularly limited, but is more preferably 0.05 μm or more in consideration of the cost for obtaining fine particles. The conductive metal powder may be a combination of two or more kinds having different particle sizes.

  The content ratio of the conductive metal powder is not particularly limited, but when the total amount of the conductive metal powder is 100 parts by mass, copper is 70 to 90 parts by mass, manganese is 5 to 30 parts by mass, and the remaining amount is A metal selected from at least one of nickel, iron, and aluminum is preferable. The content of at least one metal selected from nickel, iron, and aluminum is more preferably in the range of 1 to 20 parts by mass. By adjusting the content ratio of the conductive metal powder within this range, all of the low TCR, the low resistance value, and the low thermoelectromotive force can be achieved more reliably.

The resistor paste is formed using the above conductive metal powder and an organic vehicle as main components. And generally in the resistive paste being used more inorganic bonding agent is blended conventionally, such inorganic bonding agent in the resistive paste according to the present invention is one that is not substantially contained is there.

Here, the inorganic bonding agent, when the paste is applied and baked on the surface of the substrate to produce a resistive film, which refers to a substance contributing to the improvement of adhesion between the resistor film and the substrate Specifically, glass powder such as lead borosilicate glass, zinc borosilicate glass, calcium borosilicate glass, barium calcium borosilicate glass, bismuth borosilicate glass, magnesium borosilicate glass, and copper oxide Such as powder. Glass segregates at the interface between the resistance film and the substrate mainly due to melt flow during high-temperature firing, and physically bonds the resistance film and the substrate. Copper oxide improves the adhesion between the resistive film and the substrate by promoting chemical reaction between the conductive metal powder and the substrate to form a chemical bond.

Many of the metal elements constituting these inorganic bonding agent is a noble element from manganese, upon contact with manganese and high temperature of the conductive metal powder, even in a nitrogen atmosphere, inorganic contact with manganese is oxidized The metal oxide in the mixture (glass) is reduced. Oxidized manganese significantly lowers the sinterability, and the oxidation of manganese causes the components of the sintered body to deviate from the desired alloy ratio. There is a risk that characteristics such as resistance value and TCR may not be obtained. Also the deterioration of the inorganic contact material mixture by reduction, so that the function of the junction agent is lost. As a result, the sintering of the conductive metal powder does not proceed sufficiently, the resistance film becomes less dense, the bonding force with the substrate is lowered, the adhesion is lowered, and the resistance value stability is also lowered.

On the other hand, the paste according to the present invention, since such inorganic bonding agent is not substantially contained, it is eliminated sintering inhibiting element of manganese, manganese alloyed at the desired alloy ratio and copper As a result, the melting point is lowered, and the sintering proceeds smoothly. As a result, it is possible to obtain a resistive film having a low electrical resistivity, a low TCR, a low thermoelectromotive force, and a stable resistance value characteristic comparable to a pure alloy. Also, the interdiffusion and reaction of components between the paste and the substrate due to improved wettability to the substrate (acceleration of mutual diffusion and reaction between copper oxide and manganese oxide present in a small amount in the paste and the oxide of the ceramic substrate), and by physical anchoring effect, even without containing inorganic bonding agent, in which it is possible to obtain a high adhesion to the substrate. In the present invention, “substantially free of an inorganic bonding agent” means that, in the case of not containing any inorganic bonding agent, it is permissible to contain a small amount of an inorganic bonding agent to such an extent that it does not adversely affect. For example, it may contain an inorganic bonding agent of about 0.5% by mass or less with respect to the conductive metal powder.

  Moreover, as an organic vehicle, what melt | dissolved the organic binder in the organic solvent can be used. The organic binder is not particularly limited, but is an organic compound that is easily burned off during the baking process and has a low ash content, for example, acrylics such as polybutyl methacrylate and polymethyl methacrylate, nitrocellulose, ethyl cellulose, cellulose acetate, Celluloses such as butyl cellulose, polyethers such as polyoxymethylene, polyvinyls such as polybutadiene and polyisoprene can be used, and these are used alone or in combination of two or more. It can also be used.

  Although it does not specifically limit as an organic solvent, The organic compound which gives moderate viscosity to a resistor paste, and is easily volatilized by a drying process after apply | coating a resistor paste to a board | substrate, for example, carbitol, carbitol High boiling organic solvents such as acetate, terpineol, metacresol, dimethylimidazole, dimethylimidazolidinone, dimethylformamide, diacetone alcohol, triethylene glycol, paraxylene, ethyl lactate, isophorone can be used, These may be used alone or in combination of two or more.

  A resistor paste can be prepared by blending the conductive metal powder, the organic vehicle, and, if necessary, a surfactant, an antioxidant and the like, and mixing them. The blending ratio of each material is not particularly limited, but is preferably set in the range of 1 to 20 parts by mass of the organic binder and 5 to 20 parts by mass of the organic solvent with respect to 100 parts by mass of the conductive metal powder.

By applying the resistor paste prepared as described above to the surface of the substrate and firing it to form a resistive film, a resistor such as a current detecting resistor can be produced. The substrate is not particularly limited as long as it has electrical insulation and can withstand the high temperature of baking after applying the resistor paste. For example, a heat resistant substrate such as a ceramic substrate, a glass substrate, or a silicone substrate can be used. Ceramics include alumina, zirconia, beryllia, mullite, holsterite, cordierite, oxide ceramics such as lead titanate, barium titanate, lead zirconate titanate, and non-oxidized silicon nitride, aluminum nitride, silicon carbide, etc. Among these, alumina is particularly preferable because alumina is excellent in mechanical properties, electrical properties, cost, and the like.
There are no particular limitations on the method of applying the resistor paste and the configuration, shape, and size of the resistor to be manufactured when the resistor is manufactured using the resistor paste of the present invention. The method described in JP-A-10-199705 may be used. After the resistor paste is printed on the ceramic substrate, the solvent is dried at 100 ° C. and then fired in an inert atmosphere such as nitrogen to form a resistor film. The firing conditions of the resistor film are not particularly limited, but the peak temperature is preferably set to 700 to 1000 ° C, more preferably 800 to 950 ° C, and the peak temperature holding time is set to 10 to 30 minutes. If the peak temperature is lower than 700 ° C., the sintering may be insufficient, or the adhesion between the resistance film and the substrate may be reduced. On the other hand, when the temperature is 1000 ° C. or higher, oversintering occurs, and some metals may melt, resulting in a nonuniform resistance film.

  As a resistance film suitable for the manufacture of a low resistance resistor, the volume resistivity is preferably in the range of 20 to 200 μΩ · cm. When the volume resistivity of the resistance film is within this range, a low resistance chip resistor having a resistance value of 50 mΩ or less, particularly 10 mΩ or less can be easily manufactured. By using the resistor paste of the present invention, Such a low resistivity can be easily obtained.

  Next, the present invention will be specifically described with reference to examples.

An organic vehicle was prepared by dissolving an acrylic resin at a concentration of 30% by mass in a mixed solvent having a mass ratio of 1: 1 of tapione and carbitol. And according to the mixing | blending of Table 1, electroconductive metal powder was mixed, the organic vehicle and the inorganic type bonding agent were further added to this as needed. The mixture was stirred and mixed in an automatic mortar for 20 minutes, and then kneaded five times with three rolls to prepare resistor pastes of Examples 1 to 8 and Comparative Examples 1 to 7.

  This resistor paste was screen printed in a predetermined pattern on a 96% alumina substrate. Next, after drying this printed board for 20 minutes with a 100 ° C. blower dryer to remove the solvent, it is put into a continuous firing furnace and fired in a nitrogen atmosphere at a peak temperature of 900 ° C. for 10 minutes. Thus, the resistive films of Examples 1 to 8 and Comparative Examples 1 to 7 were produced.

The appearance, adhesion, and volume resistivity of the resistive film thus obtained were evaluated by the following methods. The results are shown in Table 1.
(appearance)
When the surface of the fired resistor film is observed with a 10-fold stereo microscope, color unevenness resulting from insufficient alloying, presence of large black particles due to oxidation of manganese, dents due to melting of the metal, etc. are significant. "X", when it was scattered, it was evaluated as "△", and when it was hardly observed, it was evaluated as "◯".

(Adhesion)
The 2 mm square resistor film formed on the substrate is peeled off with stainless steel tweezers. “○” indicates that it cannot be removed even if force is applied, “△” indicates that it can be removed if force is applied, Those that could be peeled off without much effort were evaluated as “x”.

(Resistivity)
The resistance value of the 10 mm square resistance film formed on the substrate is measured using a four-terminal resistivity meter, and the thickness of the resistance film is measured using a stylus type film thickness meter. Asked.

  As can be seen in Table 1, uniform resistance films were obtained in all of Examples 1 to 8, and the surface and cross section of the fired resistance film were scanned using a scanning electron microscope and an electron beam microanalyzer. Observation and analysis confirmed that it was well alloyed. The volume resistivity is in the range of 50 to 110 μΩ · cm in each example, and is suitable for the production of a low resistance resistor. In particular, the resistivity in Example 2 is close to the value of manganin alloy. Therefore, it was shown that it is an excellent resistor material. In addition to Examples 7 and 8, good adhesion to the substrate was exhibited. In Examples 7 and 8, since the amount of the fine conductive metal powder of 0.8 μm or less is small, the adhesion is reduced.

  On the other hand, in Comparative Examples 1 to 6, the sinterability of the resistor paste was remarkably reduced due to the presence of the glass powder, and the fired resistance film was porous and the film itself had low strength. Moreover, it was confirmed that the volume resistivity was remarkably large compared with the Example with the compounding composition of electroconductive metal powder, and the adhesive force with a board | substrate was also low. In Comparative Example 7, copper oxide was blended, but the sintering progressed to some extent, but the appearance deteriorated and the adhesion strength was obvious as compared with Example 2 where the blending composition of the conductive metal powder was the same. Decreased, and the volume resistivity increased.

Claims (6)

  A paste containing at least copper and manganese as the conductive metal powder, wherein the total amount of the conductive metal powder is 100 parts by mass, the manganese is 8 to 30 parts by mass, and the inorganic bonding agent is lead borosilicate Glass powder and copper oxide powder made of any one of glass, zinc borosilicate glass, calcium borosilicate glass, barium calcium borosilicate glass, bismuth borosilicate glass, magnesium borosilicate glass, or silica glass Resistor paste characterized by not containing substantially.   The conductive metal powder is a mixture of two or more kinds of conductive metal powders having different center particle diameters, and the conductive metal powder having a center particle diameter of 0.8 μm or less is 5% by mass or more based on the total amount of the mixture. The resistor paste according to claim 1, which is contained in an amount of 40% by mass or less.   The resistor paste according to claim 1 or 2, further comprising at least one conductive metal powder selected from nickel, iron, and aluminum. The resistor paste according to claim 3 , wherein the total amount of the conductive metal powder is 100 parts by mass, and the copper is 70 to 90 parts by mass.   A resistor, wherein a resistor film is formed by applying the resistor paste according to any one of claims 1 to 4 to a surface of an insulating substrate and baking the resistor paste.   The resistor according to claim 5, wherein the resistive film has a volume resistivity of 20 to 200 μΩ · cm.