JP2008218379A - Thick film resistor composition, resistance paste, and thick film resistor - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To form a thick film resistor having small variation in resistance values, little noise, and good electric characteristics while exhibiting a high resistance value by using a lead-free thick film resistor composition and its resistance paste. <P>SOLUTION: The thick film resistor composition of conductive particles and glass frit uses the conductive particles CaIrO<SB>3</SB>, SrIrO<SB>3</SB>, BaIrO<SB>3</SB>, or Bi<SB>2</SB>Ir<SB>2</SB>O<SB>7</SB>, and the lead-free glass frit such as borosilicate glass, aluminoborosilicate glass. The lead-free thick film resistor with the good electric characteristics can be formed by using the thick film resistor composition and resistance paste containing organic vehicle. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention is a resistor paste used for forming resistors such as thick film chip resistors and hybrid ICs, in particular, a resistor paste not containing lead, a thick film resistor composition therefor, and a film using the same. The present invention relates to a thick film resistor.

  Conventionally, as a method for forming a resistor film of an electronic component, a thick film method using a resistance paste and a thin film method using sputtering of a film forming material are well known. Among them, the thick film method is a method in which a resistor is formed by printing and baking a resistor paste on a ceramic substrate. Since the equipment is inexpensive and the productivity is high, resistors such as chip resistors and hybrid ICs are used. Widely used in the manufacture of

The resistive paste used in the thick film system is substantially composed of conductive particles and glass frit, and an organic vehicle for making them into a paste 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 a ruthenium (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.

As the 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. The borosilicate lead glass contained in is used. The reason why lead borosilicate glass is used for the glass frit is that it has good wettability with Ru-based oxides, has a thermal expansion coefficient close to that of the substrate, and is suitable for viscosity during firing.

As conductive particles other than Ru-based oxides, iridium dioxide (IrO ₂ ) has also been conventionally known (Japanese Patent Publication No. 54-1917). However, even in a resistive paste using iridium dioxide as conductive particles, glass frit containing lead such as lead borosilicate glass has been used as the glass frit.

  On the other hand, recently, from the viewpoint of environmental protection, lead-free electronic components have progressed, and lead-free resistance pastes are also strongly desired. However, in the combination of Ru-based oxide conductive particles and lead-free glass frit, it is known that the resistance value increases rapidly when the proportion of the conductive particles decreases (K. Adachi and H. et al. Kuno, “J. Am. Ceram. Soc.”, 2000, 83 [10], pp. 2441-2448). For this reason, there is a problem in that the resistance value exceeding 100 kΩ / □ formed with such a resistance paste has a large variation in resistance value and noise.

Japanese Patent Publication No.54-1917 K. Adachi and H.M. Kuno, “J. Am. Ceram. Soc.”, 2000, 83 [10], pp. 2441-2448.

  In view of such conventional circumstances, the present invention provides a thick film resistor composition, a resistance paste, and a thick film resistor that do not contain lead, and in particular, a resistance value variation while having a high resistance value. And a thick film resistor composition capable of forming a thick film resistor with low noise and good electrical characteristics, a resistor paste thereof, and a thick film resistor formed using the same. Objective.

In order to achieve the above object, the thick film resistor composition provided by the present invention comprises conductive particles and glass frit, and the conductive particles are CaIrO ₃ , SrIrO ₃ , BaIrO ₃ , and Bi ₂ Ir ₂ O. It is at least one selected from ₇ , and the glass frit is a glass frit containing no lead.

  The present invention also provides a resistive paste comprising the above thick film resistor composition of the present invention and an organic vehicle, and a thick film resistor formed from the resistive paste. To do.

According to the present invention, harmful lead can be eliminated from the resistor paste and the thick film resistor formed by using the resistor paste, thereby causing environmental pollution such as conventional resistor pastes and thick film resistors containing lead. Absent. In addition, by using the resistance paste of the present invention, a thick film resistor that does not contain lead and has high resistance and small resistance variation and noise and good electrical characteristics is formed. Can do. Moreover, since the amount of expensive Ir used can be reduced as compared with the case where IrO ₂ is used as the conductive particles, it is extremely advantageous economically.

The thick film resistor composition of the present invention is substantially composed of conductive particles and glass frit containing no lead. In addition to these essential components, various additives for adjusting the electrical characteristics of the resistor can be included. In the present invention, as the conductive particles used in combination with the glass frit containing no lead, any one selected from CaIrO ₃ , SrIrO ₃ , BaIrO ₃ and Bi ₂ Ir ₂ O ₇ is used, or two or more kinds are used. Can be used in combination. The thick film resistor composition of the present invention can contain various additives in addition to these essential components to adjust the electrical characteristics of the resistor.

As described above, ruthenium compounds (for example, RuO ₂ ) have been widely used as conductive particles. On the other hand, the ruthenium compound is not selected as the conductive particles in the present invention when the thick film resistor is formed using the ruthenium compound and the glass frit containing no lead when the conductive particles of the present invention are used. This is because noise and resistance value variations become undesirable when the resistance value is 100 kΩ / □ or more.

  However, even in the thick film resistor composition of the present invention, it is necessary to make the conductive path in the thick film resistor fine in order to prevent variation in resistance value and deterioration of noise. The average particle size is desirably 1.0 μm or less. The average particle size of the conductive particles can be calculated from the specific surface area measured by the BET method.

There is no restriction | limiting in particular about the manufacturing method of the said electroconductive particle, The thing obtained by various manufacturing methods can be used. For example, it can be manufactured by a method of mixing IrO ₂ with CaCO ₃ , SrCO ₃ , BaCO ₃ , or Bi ₂ O ₃ , roasting them, and then pulverizing them. Moreover, it can grind | pulverize so that it may become a desired average particle diameter, As a grinding | pulverization method, well-known methods, such as a ball mill, a bead mill, a jet mill, can be used.

  As for the content rate of the electroconductive particle in a thick film resistor composition, the range of 5-50 mass% is desirable. When the content of the conductive particles is less than 5% by mass, the amount of the conductive particles is too small, so that the resistance value of the resulting thick film resistor is abruptly increased and becomes difficult to control. On the other hand, if the amount exceeds 50% by mass, too much conductive particles are present, so that melting of the glass frit is hindered, and it becomes difficult for the conductive particles to become familiar (wet) with the melted glass frit, thereby aggravating the noise of the thick film resistor. .

  The glass frit 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.

  In the present invention, the fact that the glass frit does not contain lead does not mean that it does not contain lead as an inevitable impurity. Inevitable impurities cannot be avoided by refining the raw material of the glass frit, so lead mixed as an inevitable impurity in the thick film resistor composition is allowed up to about 1000 ppm by mass. The analysis of lead is performed by chemical analysis. For example, a sample can be dissolved in an acid such as sulfuric acid, nitric acid, or aqua regia, and the lead content can be measured by an ICP (inductively coupled plasma) emission spectrometer.

  In order to prevent variation in resistance value and deterioration of noise, it is necessary to make the conductive path in the thick film resistor fine. For this purpose, the average particle size of the glass frit is preferably 5 μm or less. In order to obtain a glass frit having a desired average particle diameter, the melted and cooled glass frit may be pulverized using a known pulverization method such as a ball mill or a jet mill. The average particle size of the glass frit can be measured with a known particle size analyzer using, for example, Microtrac (registered trademark).

  The glass frit used preferably has a glass transition point in the range of 500 to 600 ° C. This is because if the glass transition point is lower than 500 ° C., when the resistor paste is baked to form the resistor, the glass frit melts too much and the resistor pattern collapses. On the other hand, when the glass transition point is higher than 600 ° C., the glass frit is difficult to melt and the familiarity (wetting) with the conductive particles is deteriorated, so that the current noise of the obtained thick film resistor is deteriorated.

Further, as a characteristic of the glass frit, the thermal expansion coefficient needs to be smaller than the thermal expansion coefficient of a substrate on which a thick film resistor such as an alumina substrate is to be formed, specifically 50 to 70 × 10 ⁻⁷ / K. It is desirable to be in the range. By using a glass frit having a thermal expansion coefficient in this range, the tensile stress applied to the thick film resistor fired on the alumina substrate is relieved, and cracking of the thick film resistor can be prevented. Such characteristics of the glass frit, that is, the glass transition point and the thermal expansion coefficient can be realized by examining the composition of the glass frit.

  The resistance paste according to the present invention includes the above thick film resistor composition and the organic vehicle, and therefore does not include lead. The organic vehicle to be used may be one that is usually used for resistance pastes, for example, a resin in which ethyl cellulose, butyral, acrylic or the like is dissolved in a solvent such as terpineol or butyl carbitol acetate is used. it can.

  The molecular weight of the resin in the organic vehicle may be selected in such a range that it can be dissolved in a solvent such as terpineol and the resistance paste has a viscosity suitable for printing. For example, ethyl cellulose having a mass average molecular weight of 5,000 to 400,000 is preferable. Moreover, what is necessary is just to select the solvent which volatilizes during work, such as screen printing, and the fluidity | liquidity of a paste is not lost as a solvent, For example, it is preferable to use the solvent whose boiling point is 150 degreeC or more.

  The amount of the organic vehicle contained in the resistance paste can be appropriately adjusted within a range showing viscosity suitable for screen printing, and is usually preferably in the range of 10 to 60% by mass. In addition to the above-described essential components, the resistance paste of the present invention appropriately contains various additives, dispersants, plasticizers, and the like that have been conventionally used in order to adjust viscosity and drying properties. be able to. Moreover, in order to produce the resistance paste, each component may be kneaded as usual using a commercially available pulverizer such as a roll mill.

  Using the above-described resistance paste of the present invention, a thick film resistor that does not contain lead and has excellent electrical characteristics can be formed. For example, the resistance paste of the present invention is screen-printed on a substrate such as an alumina substrate, heated and dried to remove the solvent in the resistance paste, and then fired at a temperature of 750 to 900 ° C. in the atmosphere. Thick film resistors can be formed. In order to connect the thick film resistor to an electric circuit, electrodes such as Ag and Ag / Pd alloy are usually formed in advance at positions that are opposite ends of the thick film resistor on the substrate.

[Example 1]
An aqueous NaOH solution was added to a solution prepared with K ₂ IrCl ₆ and CaCl ₂ to obtain a precipitate. This precipitate was filtered and washed, baked at 1050 ° C. for 2 hours, pulverized with a bead mill, and further baked at 700 ° C. to prepare CaIrO ₃ powder. The average particle diameter of this CaIrO ₃ powder was 53 nm.

To 1.0 g of this CaIrO ₃ powder, a composition of 10 wt% SrO—43 wt% SiO ₂ -16 wt% B ₂ O ₃ -4 wt% Al ₂ O ₃ -20 wt% ZnO-7 wt% Na ₂ O 5.0 g of glass frit made of glass A (glass transition point 540 ° C., thermal expansion coefficient 67 × 10 ⁻⁷ / K, average particle size 1.9 μm) and 4.0 g of organic vehicle are mixed and kneaded by a three-roll mill. Thus, a resistance paste was produced. The organic vehicle was prepared by mixing 10% by mass of ethyl cellulose having a mass average molecular weight of 180,000 with 90% by mass of terpineol and heating and dissolving at 60 ° C.

  This resistance paste was screen-printed to a size of 1 mm × 1 mm on an alumina substrate on which an electrode was previously formed using an Ag—Pd paste, dried at 150 ° C. for 10 minutes, and then peaked in the atmosphere using a belt furnace. Firing was performed at a temperature of 850 ° C. for 9 minutes. With respect to the obtained thick film resistor, the sheet resistance value, resistance value variation, and noise were measured, and the results are shown in Table 1 below.

  The sheet resistance value was measured by a four-terminal method using a Model 2001 Multimeter manufactured by KEITHLEY. Noise was measured by applying 1/10 W using a noise meter Model 315C manufactured by Quan-Tech. The area resistance value and the noise are average values of 10 resistors, and the resistance value variation is a value obtained by dividing the standard deviation of the resistance value by the average value of the resistance value.

[Example 2]
IrO ₂ powder and SrCO ₃ powder were mixed, roasted at 1000 ° C. for 2 hours, pulverized with a bead mill, and further fired at 535 ° C. to prepare SrIrO ₃ powder. The average particle diameter of this SrIrO ₃ powder was 49 nm.

To 1.1 g of this SrIrO ₃ powder, 4.9 g of glass frit made of the same glass A as in Example 1 and 4.0 g of an organic vehicle were mixed and kneaded by a three-roll mill to prepare a resistance paste.

  Using this resistance paste, a thick film resistor was formed in the same manner as in Example 1 above. The electrical characteristics of the obtained thick film resistor were measured in the same manner as in Example 1, and the obtained results are shown in Table 1 below.

[Example 3]
An IrO ₂ powder and a BaCO ₃ powder were mixed, roasted at 800 ° C. for 2 hours, and then pulverized with a bead mill to prepare a BaIrO ₃ powder. The average particle diameter of this BaIrO ₃ powder was 30 nm.

1.0 g of this BaIrO ₃ powder was mixed with 5.0 g of glass frit made of the same glass A as in Example 1 and 4.0 g of an organic vehicle, and kneaded with a three-roll mill to prepare a resistance paste.

  Using this resistance paste, a thick film resistor was formed in the same manner as in Example 1 above. The electrical characteristics of the obtained thick film resistor were measured in the same manner as in Example 1 above, and the obtained results are shown in Table 1 below.

[Example 4]
The powder of IrO _{2 and} the powder of Bi ₂ O ₃ were mixed, baked at 950 ° C. for 2 hours, pulverized with a bead mill, and further baked at 850 ° C. to produce Bi ₂ Ir ₂ O ₇ powder. The average particle diameter of this Bi ₂ Ir ₂ O ₇ powder was 69 nm.

To 1.0 g of this Bi ₂ Ir ₂ O ₇ powder, 5.0 g of a glass frit made of the same glass A as in Example 1 and 4.0 g of an organic vehicle were mixed and kneaded by a three-roll mill to prepare a resistance paste. .

  Using this resistance paste, a thick film resistor was formed in the same manner as in Example 1 above. The electrical characteristics of the obtained thick film resistor were measured in the same manner as in Example 1, and the obtained results are shown in Table 1 below.

[Comparative Example 1]
0.5 g of RuO ₂ powder (average particle size 35 nm) obtained by roasting ruthenium hydroxide at 800 ° C. for 2 hours, 5.5 g of glass frit made of the same glass A as in Example 1 and 4.0 g of organic vehicle Were mixed and kneaded with a three-roll mill to prepare a resistance paste.

  Using this resistance paste, a thick film resistor was formed in the same manner as in Example 1 above. The electrical characteristics of the obtained thick film resistor were measured in the same manner as in Example 1, and the obtained results are shown in Table 1 below.

[Comparative Example 2]
To 1.0 g of the same RuO ₂ powder (average particle size 35 nm) as in Comparative Example 1, 38 wt% PbO—35 wt% SiO ₂ -6 wt% B ₂ O ₃ -6 wt% Al ₂ O ₃ -10 wt 5.5 g of a lead-containing glass frit made of glass B (glass transition point 560 ° C., thermal expansion coefficient 61 × 10 ⁻⁷ / K, average particle size 1.4 μm) having a composition of% CaO-5 wt% ZnO, and 3.5 g of the same organic vehicle as in Example 1 was mixed and kneaded with a three-roll mill to prepare a resistance paste.

  Using this resistance paste, a thick film resistor was formed in the same manner as in Example 1 above. The electrical characteristics of the obtained thick film resistor were measured in the same manner as in Example 1, and the obtained results are shown in Table 1 below.

In general, the resistance variation is desirably 5% or less, and those exceeding 10% are not practical thick film resistors. Further, the noise is desirably 10 dB or less, and if it exceeds this, it cannot be said that it is a practical thick film resistor. The comparative example 2 is a conventional example using RuO ₂ conductive particles and lead-containing glass frit, and the resistance value variation and noise of the thick film resistor are in the above desired range.

As is clear from the results of Table 1 above, the thick film resistors according to Examples 1 to 4 of the present invention have small resistance value variation and noise of the thick film resistors while using glass frit that does not contain lead. It has the same electrical characteristics as Comparative Example 2 using the lead-containing glass frit as an example. On the other hand, in Comparative Example 1 in which the conductive particles are RuO ₂ and lead-free glass frit is used, it can be seen that the resistance variation and noise of the resulting thick film resistor are extremely large.

Claims (3)

A thick film resistor composition comprising conductive particles and glass frit, wherein the conductive particles are at least one selected from CaIrO ₃ , SrIrO ₃ , BaIrO ₃ , and Bi ₂ Ir ₂ O ₇ , A thick film resistor composition, wherein the glass frit is a glass frit containing no lead.   A resistive paste comprising the thick film resistor composition according to claim 1 and an organic vehicle.   A thick film resistor formed from the resistor paste according to claim 2.