KR880000423B1 - Indium oxide resistor inks - Google Patents

Abstract

A resistor ink for forming a resistor film on a circuit board comprises 25-80 (Pref. 30-45) wt.% In203; 0.1-20 (pref. 3-8) wt.% MgO; 5-60 (pref. 30-45)% Ba-Ca borosilicate glass frit; and 19-35 (pref. 20-30)% organic vehicle. The glass frit pref. consists of 40- 55 (esp. 52) wt.% BaO; 10-15 (esp. 12) % CaO; 14-25 (esp. 16)% B2O3; and 13-23 (esp. 20) % SiO2. A circuit board, pref. porcelain coated metal (esp. steel), has a coating of resistor ink as above on part of its circuit.

Description

Indium oxide resistor ink

The present invention relates to a thick film resistor ink made of indium oxide having an improved temperature coefficient of resistance, and also for use in multilayer electrical structures on magnetically coated metal organs.

It is well known in the art to use specialized ink formulations to form thick films with various functions on suitable substrates that make up the structure of multilayer integrated circuit structures. This technology has attracted interest in the ability to construct very dense multilayer circuit patterns on various substrates with a wide range of applications in the electronics industry.

Substantially improved substrates for the construction of such circuits are described in US Pat. No. 4,256,796, which was invented by Mr. Hang et al. And patented on March 17, 1981, the contents of which are incorporated herein by reference. Reflected in The substrate developed by Cheng et al. Is an improved mixture of magnesium oxide or magnesium oxide and some other oxides based on the amount of oxides, consisting of barium oxide (BaO), boron trioxide (B ₂ O ₃ ) and silicon dioxide (SiO ₂ ). The magnetic composition was coated on a metal. Preferred metals here are steel, in particular low carbon content steel, which may be coated with various metals, for example copper. The magnetic composition is applied to the metal core and sintered to produce a magnetic coating film in which glass is partially removed from the metal core. This coating film has a very low viscosity at its initial melting point and soon afterwards obtains a high viscosity due to glass removal. Sintered coating films that are well suited for hybrid circuits have a deformation temperature of at least 700 ° C. and a high coefficient of thermal expansion of at least 110 × 10 ⁻⁷ / ° C.

The self-coated metal substrate developed by Cheng et al. Has superior properties compared to previously known metal substrates, whereas it is only incompatible with, or even poorly, commercially available thick film inks. There is a vulnerability in that. In addition to the need for development of inks compatible with the substrates developed by CN and others, the need for means to control the temperature coefficient (TCR) of the resistor that moves quickly from zero or optimum as the resistance of the resistor increases. Generally accepted sea.

According to the present invention, there is provided a means by which the TCR of the indium oxide resistor can be controlled within the acceptance limit, that is, within the 350 ppm / ° C plus or minus range even when the resistance value is high.

An improved resistor ink provided in accordance with the present invention consists of indium oxide, magnesium oxide as the TCR control component, barium calcium, borosilicate glass and a suitable organic medium.

According to the present invention, improved media and high resistance resistor inks useful for producing complex single or multi-layer thick film circuits on magnetically coated metal circuit boards, i.e. resistances of greater than about 500 ohms to 1 megohm per unit area Ink with a value is provided. The resistor ink of the present invention is not only particularly useful in connection with magnetic coated metal substrates developed by Heng et al, and ink of various types of thick films specially prepared therefor, but also effectively used in conventional substrates such as alumina substrates. have.

The novel resistor inks of the present invention consist of indium dioxide, magnesium dioxide, barium calcium borosilicate glass raw materials and suitable organic media. The addition of magnesium oxide as a control component in accordance with the present invention provides a resistor ink with high resistance and with an acceptable TCR value exceeding expectations.

Indium oxide should be of high purity, especially the particle size should be in the range between about 1.0 and 1.2 micrometers. Indium oxide occupies about 25 to about 80 weight percent (preferably about 30 to 45 weight percent) in the subject ink.

The magnesium oxide TCR control component of the subject ink makes up about 1 to about 20 percent (preferably about 3 to about 8 percent) by weight in the ink formulation. By varying the amount of magnesium oxide in the main ink, the TCR of this film, which usually has a negative value, is within tolerance and often close to zero.

Barium calcium borosilicate glass raw materials of the novel ink according to the present invention are, by weight, a) about 40 to about 55 percent (preferably about 12 percent) and b) about 10 to about 15 percent (preferably About 16 percent) of calcium oxide, c) about 14 to about 25 percent (preferably about 16 percent) of boron trioxide, and d) about 13 to about 23 percent (preferably about 20 percent) of silicon dioxide. It is composed. This glass stock powder occupies about 5 to 60 percent (preferably about 30 to about 45 percent) by weight in the subject ink.

Organic media are, for example, cellulose derivatives, in particular binders such as ethyl cellulose, synthetic resins such as polyacrylate or mesaacrylate, polyesters, polyolefins and the like. In general, media commonly used in the inks of the type described herein are, for example, available as Amoco A-25, Amoco H-50 and Amoco L-100 from Amoco Chemicals Corporation. Pure liquid polybutenylene and poly n-butyl mesaacrylate sold by EI dupont de Nemours and Co.

The above resins were used separately or in combination of two or more. If necessary, suitable viscosity regulators may be added to the resin material, such as those commonly used in similar ink formulations, such as Texas Eastman Company, such as Texanol. Commercially available ester alcohols, pine oil, terpineol, butyl carbiol acetate or NL Solid materials such as castor oil derivatives sold under the tradename thixatrol from Industries. The organic medium comprises about 10 to about 35 weight percent (preferably about 20 to about 30 weight percent) in the subject ink.

The novel ink of the present invention is a substrate such as conventional alumina plates or magnetically coated metal plates developed by CN and the like by conventional means such as screen printing, brushing, spraying, etc. Cree printing is preferred). The coating film of ink is then sintered in air at 100-125 ° C. for 4-10 minutes. As is commonly done in this technique, the subject resistor ink is usually applied and sintered onto the substrate after all lead ink has been applied and sintered. The resistance value of the sintered film can be adjusted by conventional means such as laser polishing or air polishing. The film formed with the main resistor ink has excellent TCR value, low current noise, good stability against laser trimming and thermal shock effect, and excellent soldering, thermal charging, power load, and moisture. In addition, this proved to be excellent in chemical compatibility with magnetically coated metal films such as CN and inks formed specifically for this.

The following examples specifically illustrate the present invention, which is to be understood that the present invention is not intended to be limited to that described herein, wherein the proportions of all components are expressed in weight and the units of temperature are otherwise stated. If not, it is Celsius.

EXAMPLE

Resistor inks were prepared from the following formula.

In the above formula, the glass powder has the following composition, the ratio of which is indicated in parentheses in weight units.

BaO (51.5); CaO (12.58); B ₂ O ₃ (15.62); SiO ₂ (20.21).

The medium is a 6% solution of ethyl cellulose, ester alcohol texanol. Formulas F and H additionally contained 1.5 l and 3.03 percent of texanol, respectively, to adjust the flow of ink.

The powder components are synthesized with an organic medium, which is first mixed by hand and then mixed by three rolling mills with shear to obtain a smooth paste suitable for screen printing. Additional media was added to compensate for the loss and maintain proper fluidity during mixing.

Copper lead ink was applied to a magnetically coated steel substrate of the type described by CN and the like and then sintered. The ink was then printed onto a substrate using 325 mesh stainless steel and a thick emulsion of 0.3 to 0.6 mils, then dried in air at 125 ° ± 10 ° for about 15 minutes and peak temperature 900 ± 10 ° for 4-7 minutes. And sintered in nitrogen gas. Sheet resistivity and hot and cold TCR were determined for each composition formula. The results are shown in the table below.

[table]

^* Contains magnesium oxide.

The effect of the amount of magnesium oxide on the TCR in the compositional formula of the present invention can be easily seen from the data in the above table. For example, it is expected from proceeding from ink E to F that an increase above the threshold in sheet resistivity can cause the TCR to be at about -1000. However, the addition of magnesium oxide in accordance with the present invention results in a four-fold reduction in both hot and cold TCR over expectations.

Claims (10)

a) about 25 to 80 weight percent of indium oxide, b) about 1 to 20 weight percent of magnesium oxide, c) about 5 to about 60 weight percent of barium calcium borosilicate glass raw material, and d) about 10 to about 35 Resistor ink adapted to form a resistor film on a circuit board composed of a weight percent suitable organic medium. The method of claim 1, wherein the ink comprises about 30 to about 45 weight percent of indium oxide, about 3 to about 8 weight percent of magnesium oxide, about 30 to about 45 weight percent of the glass, and about 20 to about 30 Resistor ink consisting of the media in weight percent. The method of claim 1, wherein the glass material comprises about 40 to about 55 weight percent barium oxide, about 10 to about 15 weight percent calcium oxide, about 14 to about 25 weight percent boron trioxide, and about 13 to about Resistor ink consisting of 23 weight percent silicon dioxide. 4. The resistor ink of claim 3 wherein the glass stock comprises about 52 weight percent barium oxide, about 12 weight percent calcium oxide, about 16 weight percent boron trioxide, and about 20 weight percent silicon dioxide. A circuit board having a coating film of resistor ink on a portion of the surface, the coating film of the resistor ink comprising: a) about 25 to about 80 weight percent of indium oxide, b) about 1 to about 20 weight percent of magnesium oxide; c) about 5 to about 60 weight percent of barium calcium borosilicate glass stock and d) about 10 to about 35 weight percent of a suitable organic medium. 6. The circuit board of claim 5, wherein the substrate is a magnetic coated metal. The circuit board of claim 6, wherein the metal is steel. An electronic device comprising a circuit board having a circuit formed thereon, wherein the circuit contains a resistor film formed by applying and sintering a resistor ink, the resistor ink comprising: a) about 25 to about 80 weight percent of indium oxide, and b) about 1 To about 20 weight percent magnesium oxide, c) about 5 to about 60 weight percent barium calcium borosilicate glass material, and d) about 10 to about 35 weight percent suitable organic medium. 9. The electronic device of claim 8 wherein the circuit board is a magnetic coated metal circuit board. The electronic device of claim 9 wherein the metal is steel.