JPH01147803A - Resistance paste - Google Patents

Abstract

PURPOSE:To obtain resistance paste displaying excellent TCR characteristics, and to acquire the resistance paste having the resistance value of superior characteristics by adding approximately 5-30wt.% boron nitride to a solid component. CONSTITUTION:A metallic hexaboride and reduction-resistant glass frit are dispersed into an organic vehicle, thus acquiring resistance paste. Approximately 5-30wt.% boron nitride is contained to the metallic hexaboride and the reduction-resistant glass frit at that time. Aliphatic alcohol, the ester of such alcohol such as acetate, propionate, etc., are used as the organic vehicle. Boron nitride is employed for inhibiting the increase of a resistance value at a time when the resistance paste is baked to a thick-film resistor and obtaining superior TCR characteristics. Accordingly, the resistance paste displaying surpassing TCR characteristics is acquired, and the resistance paste having the resistance value of excellent characteristics is obtained with superior reproducibility.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of the Invention The present invention relates to a resistive paste that can be formed as a thick film resistor on a substrate such as alumina together with a base metal such as copper as a conductor, and in particular to its composition.

Conventional wave' and its problems α In recent years, base metals such as copper have been increasingly used in electrodes or conductive patterns of thick film electric circuit boards, and there is a demand for resistance pastes that can be fired together with copper in a reducing atmosphere.

This type of resistance paste is basically a dispersion of a metal hexaboride as a conductive component and a glass frit as a binder in an organic vehicle as a solvent.
It is necessary that the thick film resistor exhibit good characteristics when fired in a reducing atmosphere to form a thick film resistor.

Therefore, conventionally, as described in Japanese Patent Publication No. 59-6481, Japanese Patent Application Laid-open No. 55-27700, Japanese Patent Application Laid-Open No. 55-29199, metal hexaborides such as LaBg and reduction-resistant glasses such as boalumin were used. Resistance pastes containing calcium oxide glass, Ba borosilicate glass, and Ca-based glass have been proposed.

However, the resistance paste obtained here can be put to practical use in the range of 10 to IOKΩ when fired into a thick film resistor by using LaBa with a relatively small diameter. When IOKΩ is exceeded, the temperature resistance characteristic (TCR), which is an important characteristic of a resistor, decreases by -1000p.
It has the problem that it deteriorates to more than pm/''C and cannot be put into practical use.

Therefore, the present invention provides TCR up to a sheet resistance value of about 2MΩ.
A thick film resistor with excellent characteristics can be obtained, and depending on the mixing ratio of solid components (conductive component, glass frit, and boron nitride) in the organic vehicle, a constant and stable resistance can be obtained when the thick film resistor is made. The purpose is to provide a resistor paste that can reproduce the values.

The resistance paste according to the present invention contains, in addition to a metal hydroboride and a reduction-resistant glass frit, dispersed in an organic vehicle about 5 to 30% of boron nitride based on these solid components. It is characterized by the fact that

Organic vehicles are inert liquids used as solvents. Examples of organic vehicles that can be used are aliphatic alcohols,
Esters of such alcohols such as acetate and propionate, terpenes such as pine oil, terpineol, etc., solutions of resins such as polymethacrylates of lower alcohols or solutions of ethylcellulose in solvents such as pine oil and monobutyl ether of ethylene glyfur monoacetate. Particularly preferred is an acrylic resin dissolved in α-terpineol. The vehicle may contain a volatile liquid to promote rapid curing after application to the substrate.

The ratio of organic vehicle to solid components in the resistance paste of the present invention is not necessarily constant depending on the method of dispersing the solid components and the type of vehicle used.

Metal hydroborides can be used as conductive components, such as La
Ba, YBa*CaB1*BaBs,
Including Sr's etc.

Glass frit is used as a conductive component during firing or as a bonding agent to the substrate, and has an insulating property, and BsOs
, Sing ,' BaO, CaO, KtOr M
gO, SrO.

Contains borosilicate alkaline earth oxides such as ZrO, particularly about 0.5 to 5.0 mo of niobium oxide (NbxOi)
Addition of 1% is effective in suppressing increase in resistance value.

As shown in Table 1 below, boron nitride (BN) suppresses the increase in resistance value when fired into thick film resistors and provides good TC.
Used to obtain R characteristics. The effect of adding BN begins to be exhibited when the amount exceeds about 5 wt % based on the solid component, and when it exceeds about 30 wt %, the resistance value increases on the contrary.

Note that the mixing ratio of metal water boride, glass frit, and boron nitride can take any value depending on the required resistance value.

EXAMPLES Hereinafter, examples of the resistance paste according to the present invention will be explained in detail.

The resistance pastes of Examples 1 to 7 shown in Table 1 below were prepared by incorporating LaBa as a conductive component and glass frit and BN as binders in an organic vehicle consisting of acrylic resin-α-terpineol as a solvent. They were dispersed at the mixing ratios shown in each of Examples 1 to 7.

[Margin below] The LaB 6 used was treated with a vibration mill to reduce the average particle size to 0.8.
It is expressed in μm. The glass frit is Ba0(1
9,39mo1%), Cab (9,05mo1%),
BzO* (35,26 mo1%).

SiOx (30,97mo1%L Nb*Os (2
, 39 mo1%) and KzO (2.95 mo1%).

Specifically, the raw materials constituting the glass frit component are mixed according to the mixing ratio, the mixed raw materials are allowed to melt in a platinum crucible, are poured into cold water, and are ground by a wet ball mill to form a frit.

The above composition of LaBa, glass frit, and BN is dispersed in an organic vehicle by two-part milling to form a paste.

The organic vehicle is 85 wt% α-
A terpineol solution containing 15% acrylic resin dissolved therein was used. The organic vehicle is 28% by weight based on solids. '-Also, as shown in Table 2, as Comparative Examples 1 to 3, resistance pastes were manufactured using the same components as in each of the above-mentioned Examples and following the same procedure. Comparative Example 1.2 is an example in which BN is not added, and Comparative Example 3 is an example in which 40 wt % of AIN is added to other solid components.

The resistor paste produced as described above was screen printed on an alumina substrate between pre-fired copper electrodes, and heated to 120°C.
After drying for 10 minutes, it was fired. Firing was performed at 900°C in a nitrogen atmosphere furnace.

The sheet resistance values and TCR of the thick film resistors of each example and comparative example are shown in Tables 1 and 2. Example 1~
All of No. 7 exhibited sheet resistance values of 2.3 to 2.3 MΩ, and had good TCR characteristics. The area resistance value is 2.
Even in Example 6, which has the highest value of 3MΩ, the TCR characteristic is 13.
It is 52 ppm/''C, which is at a practical level.

On the other hand, Comparative Examples 1 and 2 in which BN was not added had low sheet resistance values and a narrow range of resistance values. Further, in Comparative Example 3 in which 40 wt % of BN was added, the sheet resistance value was 169 or more, and it virtually did not function as a resistor of a circuit element.

Therefore, when the mixing ratio of the glass frit is reduced in order to lower the resistance value, the bonding force between the solid components is weakened, a strong resistance film is not formed, and the adhesion with the substrate is also deteriorated.

It should be noted that the resistance paste according to the present invention is not limited to the above-mentioned examples, and the organic bisilicate metal hexaboride and the borosilicate alkaline earth oxide as the main component of the glass frit are within the scope of the present invention. Various types can be selected, and their composition ratios are also arbitrary.

Effects of the Invention As is clear from the above explanation, according to the present invention, approximately 5 to 30 wt% of boron nitride is added to the solid component, so when a thick film resistor is formed, the area resistance value is 10. niΩ
It is possible to obtain a resistive paste exhibiting good TCR characteristics even when the resistance exceeds the above. Furthermore, by adjusting the mixing ratio of each solid component, it is possible to obtain resistivity values with good characteristics over a wide range with good reproducibility.

Patent applicant: Murata Manufacturing Co., Ltd.

Claims (1)

[Claims] (1) In a resistance paste in which a metal hexaboride and a reduction-resistant glass frit are dispersed in an organic vehicle, about 5 to 3
A resistance paste comprising 0 wt% boron nitride.