WO2018074562A1 - Resistive paste and resistor produced by firing same - Google Patents

Abstract

Provided are: a lead-free thick film resistor which has good electrical characteristics such as low current noise, while having a high resistance; and a lead-free resistive paste which serves as a starting material for this resistor. A resistive paste which contains conductive particles that are formed from ruthenium dioxide, a glass frit that does not contain lead, an organic vehicle and an additive, and wherein from 5% by mass to 12% by mass (inclusive) of amorphous silica having a specific surface area of from 60 m²/g to 125 m²/g (inclusive) is contained as the additive.

Description

Resistive paste and resistor produced by firing the same

The present invention relates to a resistor paste used as a resistor material such as a thick film chip resistor or a hybrid IC, and more particularly to a resistor paste not containing lead and a resistor produced by firing the paste.

Conventionally, as a method for forming a resistor film of an electronic component, a thick film method in which a film is formed using a resistance paste containing a film forming material and a thin film method in which a film forming material is formed by sputtering or the like are generally used. Are known. Among them, the thick film method is to form a resistor by printing a resistor paste on a ceramic substrate and then firing it. This method is inexpensive and has high productivity required for film formation. It is widely used for manufacturing resistors included in electronic components such as chip resistors and hybrid ICs.

The resistive paste used in the above thick film system contains conductive particles and glass frit, and an organic vehicle for making them suitable for printing. As the conductive particles, ruthenium dioxide (RuO ₂ ) or pyrochlore-type ruthenium-based oxides (Pb ₂ Ru ₂ O _7-X , Bi ₂ Ru ₂ O ₇ ) are generally used. The reason why the Ru-based oxide is used as the conductive particles is mainly because the resistance value changes gently with respect to the concentration of the conductive particles.

In addition, as a glass frit, a large amount of lead such as lead borosilicate glass (PbO—SiO ₂ —B ₂ O ₃ ) and lead aluminoborosilicate glass (PbO—SiO ₂ —B ₂ O ₃ —Al ₂ O ₃ ) is used. Including lead borosilicate glass. The reason why the lead borosilicate glass is used for the glass frit in this way is that it has good wettability with the Ru-based oxide, has a thermal expansion coefficient close to that of the substrate, and has a suitable viscosity during firing.

In the above-described resistance paste, various additives have been included for a long time in order to improve the characteristics of the resistor after film formation. For example, Patent Document 1 discloses a thick film resistor excellent in electrical characteristics by mixing a refined ruthenium oxide powder, a glass containing PbO, and niobium oxide (Nb ₂ O ₅ ) together with an inert vehicle. A technique for producing a resistive paste is disclosed.

Japanese Examined Patent Publication No. 63-035081

However, when Nb ₂ O ₅ is used as an additive, the characteristics can be improved with a small addition amount, but the resistance value is also greatly changed, so that there is a problem that it is difficult to adjust the resistance value. In recent years, lead-free electronic components have been promoted in consideration of environmental protection, and lead-free solder pastes are also required. In addition, electronic components made from the above-mentioned resistance paste are becoming increasingly smaller and have higher performance, and as a result, resistance resistors with higher resistance and lower current noise are produced. What can be done is required.

The present invention has been made in view of the above situation, and can form a lead-free thick film resistor excellent in electrical characteristics capable of suppressing current noise while having a high resistance value. An object is to provide a lead-free resistance paste.

As a result of repeated studies on a lead-free resistance paste capable of achieving the above object, the present inventor uses a lead-free oxide containing ruthenium in conductive particles by including a specific additive in the resistance paste. At the same time, it has been found that a resistor having good electrical characteristics can be produced even when a lead-free glass frit is used, and the present invention has been completed.

That is, the resistance paste provided by the present invention is a resistance paste containing conductive particles made of ruthenium dioxide, a glass frit containing no lead, an organic vehicle, and an additive, wherein the additive has a specific surface area. It is characterized by containing 5% by mass or more and 12% by mass or less of amorphous silica of 60 m ² / g or more and 125 m ² / g or less.

According to the present invention, there is provided a resistance paste capable of producing a thick film resistor excellent in electrical characteristics capable of suppressing current noise to a low level while having a high resistance value without causing environmental pollution due to lead. Can do.

Hereinafter, embodiments of the resistance paste of the present invention will be described. There is no restriction | limiting in particular about the form of ruthenium dioxide as electroconductive particle contained in this resistance paste of embodiment of this invention, The oxide obtained by a general manufacturing method can be used. However, in order to suppress the variation in resistance value and current noise of the thick film resistor formed by firing as much as possible, it is desirable to make the conductive path in the thick film resistor finer. The average particle diameter by diameter is preferably 1.0 μm or less.

The glass frit contained in the resistance paste is not particularly limited as long as it does not contain lead. For example, borosilicate glass, aluminoborosilicate glass, borosilicate alkaline earth glass, borosilicate alkali glass, borosilicate zinc glass, borosilicate bismuth glass, or the like can be used. As described above, D50 (median diameter) measured by laser diffraction particle size distribution measurement of glass frit to minimize the conductive path in the thick film resistor and suppress variations in resistance value and current noise of the thick film resistor as much as possible. Is preferably 5 μm or less.

The organic vehicle contained in the resistance paste may be one that is usually used in resistance pastes, for example, a resin in which a resin such as ethyl cellulose, butyral, or acrylic is dissolved in a solvent such as terpineol or butyl carbitol acetate. Preferably used.

The resistance paste further contains 5% by mass to 12% by mass of amorphous silica (SiO ₂ ) having a specific surface area of 60 m ² / g or more and 125 m ² / g or less as an additive. Amorphous silica has a function of increasing current resistance by increasing the resistance value of the resistor formed by firing. The reason why the specific surface area of amorphous silica is limited to 60 m ² / g or more and 125 m ² / g or less is that current noise (dB) is hardly negative when the specific surface area is less than 60 m ² / g, and conversely 125 m ² / g. This is because the viscosity of the resistance paste becomes too high and it becomes difficult to prepare the resistance paste. In addition, the content of amorphous silica is set to 5% by mass or more and 12% by mass or less with respect to the resistance paste. This is because the current noise (dB) is unlikely to become negative even if the value exceeds the value.

The method for producing the resistance paste of the above-described embodiment of the present invention is not particularly limited, and a predetermined amount of the components of the resistance paste described above is weighed into a commercially available kneading apparatus such as a roll mill, and kneaded. Can be produced. At that time, the mixing ratio of the conductive particles and the glass frit is preferably about 5/95 to 50/50 in terms of the ratio of the conductive particles / glass frit on a mass basis. Further, the method for manufacturing the resistor is not particularly limited, and the resistor can be formed by the same method as the conventional one using the resistor paste of the embodiment of the present invention as a material. For example, the above-mentioned resistance paste is applied to a normal substrate such as an alumina substrate by screen printing or the like, dried, and then fired at a peak temperature of about 800 to 900 ° C. using a belt furnace or the like, thereby lead-free. Can be formed.

In addition to the essential components described above, the resistor paste according to the embodiment of the present invention is conventionally used in various ways such as dispersants and plasticizers that are conventionally used to adjust the electrical characteristics of thick film resistors. You may add an additive as needed.

Conductive particles, glass frit, organic vehicle, and additives are mixed at various blending ratios to prepare multiple resistor paste samples, which are then fired to form thick film resistors and their electrical properties Was evaluated. Specifically, RuO ₂ powder having a BET diameter of 40 nm prepared by roasting ruthenium hydroxide was prepared as the conductive particles. The glass frit was prepared by mixing, melting, quenching and pulverizing by a general method, 10 mass% SrO-43 mass% SiO ₂ -16 mass% B ₂ O ₃ -4 mass% Al ₂ O ₃ -20 mass A glass frit having a composition of% ZnO-7 mass% Na ₂ O and having a D50 of 1.9 μm as measured by laser diffraction particle size distribution was prepared.

Five types of amorphous SiO ₂ having specific surface areas of 3 m ² / g, 30 m ² / g, 60 m ² / g, 80 m ² / g, and 125 m ² / g are prepared as additives, and organic vehicles are used as organic vehicles. A material mainly composed of ethyl cellulose and terpineol was prepared. These RuO ₂ powder, glass frit, additive, and organic vehicle were weighed so as to have various blending ratios and kneaded by a three-roll mill. Thus, resistance pastes of Samples 1 to 17 were produced.

Next, an alumina substrate on which two electrodes having an interelectrode distance of 1 mm are formed using AgPd paste is prepared for the resistance paste of each sample, and the two electrodes are connected on the alumina substrate. The film was screen-printed to a width of 1 mm, dried at 150 ° C. for 10 minutes, and then fired in a belt furnace at a peak temperature of 850 ° C. for 9 minutes. The electrical characteristics (resistance value, current noise) of the thick film resistor thus fabricated were measured. The composition of the resistance paste and the characteristics of the resistor obtained by each paste are shown in Table 1 below. The resistance value was measured by a 4-terminal method using a Model 2001 Multimeter manufactured by KEITHLEY, and the current noise was measured by applying a 1/10 W using a noise meter Model 315C manufactured by Quan-Tech.

As can be seen from Table 1, in the case of forming a thick film resistor with conductive particles and lead-free glass frit consisting of low-cost RuO ₂ also, a specific surface area of 60 m 2 / ^g or more as an additive 125m ² / by g or less amorphous SiO ₂ is present invention is added in a range defined, the addition of amorphous SiO ₂ in a manner that does not meet the requirements for and the present invention without added amorphous SiO ₂ It can be seen that the current noise can be reduced compared to the case.

Claims (4)

A resistive paste containing conductive particles made of ruthenium dioxide, glass frit containing no lead, an organic vehicle, and an additive, having a specific surface area of 60 m ² / g or more and 125 m ² / g or less as the additive. A resistive paste comprising amorphous silica in an amount of 5% by mass to 12% by mass. A lead-free resistor formed by firing the resistor paste according to claim 1. An electronic component comprising the resistor according to claim 2. A method for producing a lead-free resistor, wherein the resistor is produced by firing the resistor paste according to claim 1.