JPH0238459A - Composition suited for organic thick film resistance element - Google Patents

Abstract

PURPOSE:To provide a composition which can give an organic thick film resistance element excellent in stability, etc., by dispersing a thermosetting resin comprising a tetracarboxylic acid dianhydride, diaminodiphenylmethane, a lactam compound and carbon in a dispersing medium such as an alcohol. CONSTITUTION:A thermosetting resin composed of tetracarboxylic acid dianhydrides of formula I and/or, diaminodiphenylmethane and/or diaminodiphenyl sulfone and a lactam compound (e.g., gamma-butyrolactam) and carbon (e.g., acetylene black) are dispersed in a dispersing medium such as an alcohol and/or a ketone. The obtained paste 16 is applied between electrodes 14 and 14 provided on a substrate 10 to form an organic thick film resistance element. In this way, a resistance element which scarcely suffers any change in its resistance value even when subjected to long-term heating can be obtained.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a composition suitable for organic thick film resistive elements, particularly for organic thick film resistive elements used as electrical resistive elements in electronic circuits such as substrates. Regarding suitable compositions.

[Prior Art] An organic thick film resistance element is made of carbon powder and a thermosetting resin, and is formed as a thin film between electrode terminals of a substrate. When forming an organic thick film resistance element, carbon powder and thermosetting resin are formed into a paste using an appropriate dispersion medium, and the paste carbon powder is applied between electrodes or lead terminals on a substrate by screen printing or the like. is applied to. The coating layer is heated and cured to form an organic thick film resistive element between the electrodes. The resistance value of the organic thick film resistance element can be increased to 100Ω by changing the blending ratio of carbon powder and thermosetting resin.
It can be adjusted within the range of /1 to 1M07.

Conventionally, epoxy resins, phenol resins, polyimide resins, and the like have been used as thermosetting resins for the base of such organic thick film resistance elements.

[Problems to be Solved by the Invention] However, when an epoxy resin or phenol resin is used as a composition in an organic thick film resistor element, high temperatures (15
If exposed to temperatures above 0°C for a long period of time, there is a problem in that the resistance value changes significantly over time. In addition, conventional organic thick film resistance elements using polyimide resin do not have a general-purpose dispersion medium that dissolves the base polyimide resin, and special highly polar dispersion media such as N-methylpyrrolidone and N,N'-dimethylformamide have to be used. Since a dispersion medium is used, screen printing (for example, emulsion of polyvinyl alcohol or acrylic resin) or squeegee may be melted or damaged during screen printing, which poses a practical problem. Furthermore, there is a problem that the shrinkage during curing is large, making it difficult to obtain a stable resistance value.

The present invention was developed in view of the above circumstances, and it is possible to use a dispersion medium that does not cause damage to the screen emulsion, squeegee, etc., and it is possible to use a dispersion medium that does not cause damage to the screen emulsion or squeegee. It is an object of the present invention to provide a composition suitable for an organic thick film resistance element made of a polyimide thermosetting resin that does not change.

[Means for Solving the Problems] In order to achieve the above object, the present invention provides a composition suitable for an organic thick film resistance element, particularly a composition for an organic thick film resistance element, whose structural formula is represented by the following: A thermosetting resin consisting of tetracarboxylic dianhydride, diaminodiphenylmethane and/or diaminodiphenylsulfone, and a lactam compound, and carbonine are dispersed in a dispersion medium of alcohols and/or ketones. Features.

[Function] According to the composition suitable for the organic thick film resistance element according to the present invention, the mixture of tetracarboxylic dianhydride, diaminodiphenylmethane and/or diaminodiphenylsulfone, and lactam compound contains alcohols and ketones. It is compatible with dispersion media such as, and is stable in the dispersion media.

Therefore, a paste of carbon powder and thermosetting resin can be easily created and kept in a stable state. The organic thick film resistance element heat-cured from the paste has sufficient heat resistance, and its resistance value does not change even after long-term heating.

Note that since alcohols, ketones, etc. can be used as the dispersion medium, they do not damage the screen emulsion or the squeegee.

[Preferred Embodiments of the Invention] Detailed embodiments of the composition suitable for the organic thick film resistance element according to the present invention will be described below.

FIG. 1 is a cross-sectional view of an electric circuit board on which an organic thick film resistive element is formed based on the composition according to the present invention. As shown in FIG. 1, an undercoat 12 (undercoat printing) is applied to the upper surface of the substrate 10, and electrodes 1414 are formed on the undercoat 12 by electrode printing. Between the electrodes 14 and 14, an organic thick film resistive element 16 according to the invention is formed by screen printing, and an overcoat 18 (protective printing) is formed on the organic thick film resistive element 16. This results in
A resistive element is formed on the electrode 14.14 on the substrate 10. Moreover, FIG. 2 is a plan view of an electric circuit board on which an organic thick film resistance element based on the composition according to the present invention is formed.

The organic thick film resistive element is made of a mixture of carbon and thermosetting resin, and the carphone and thermosetting resin are mixed in a dispersion medium to form carphone paste.

The carphone paste is applied by printing between the electrodes of the substrate using a 200-325 mesh nylon or stainless steel screen. The coating paste is heated and dried at a temperature of 150 to 230° C. for 30 to 180 minutes, and the thermosetting resin in the coating paste is partially cured to form an organic thick film resistive element between the electrodes.

For example, powdered carbon such as kedgen black, acetylene black, furnace black, graphite, etc. is used. It is preferably used in the form of particles for ease of handling.) is preferably in the range of 1 to 1000 mμ.

The mixing ratio of carbon powder and thermosetting resin is determined as appropriate; when it is desired to increase the resistance between the electrodes, the ratio of carbon powder is decreased; when it is desired to reduce the resistance between the electrodes, the ratio of carbon powder is decreased. A percentage is increased. By changing the mixing ratio of carphone powder and thermosetting resin, the organic thick film resistance element is usually adjusted within the range of 100Ω/hole to IOMΩ/hole.

Is the thermosetting resin structural formula II II II (3,4,3'
, 4'-diphenylbenzophenone tetracarboxylic dianhydride) and/or 11 II II (1;1 (3,4,3', 4'-diphenylsulfone tetracarboxylic dianhydride)) It is composed of an anhydride, diaminodiphenylmethane and/or diaminodiphenyl sulfone, and a lactam compound.

The blending molar ratio of tetracarboxylic dianhydride and diaminodiphenylmethane and/or diaminodiphenyl sulfone is used in the range of 0.5 to 1.5, preferably 0.5 to 1.5.
It is used in the range of 8 to 1.2. A composition for an organic thick film resistor element based on such a compounding ratio has excellent heat resistance and no change in resistance value over time.

Further, alcohols or ketones are used as a dispersion medium for these mixtures, and the mixtures are dispersed in a stable state (stable for 3 months or more at room temperature). Since alcohols and ketones usually do not pose a risk of dissolving and damaging the screen emulsion or sugichi, suitable compositions for the polyimide-based organic thick-film resistive element are different from conventional polyimide-based resin resistive elements. It has usability.

Lactam compound <R-靜π正〒πn11) is n or 1-6
A molar ratio of the lactam compound and tetracarphonic dianhydride is used in the range of 0.3 to 0.3. The lactam compound has the function of making tetracarphonic dianhydride compatible with a solution of diaminodiphenylmethane and/or diaminodiphenyl sulfone and alcohols or ketones.

Diaminodiphenylmethane includes 4,4'-diaminodiphenylmethane, 3.4'-diaminodiphenylmethane, 3.3'-diaminodiphenylmethane, etc., and diaminodiphenyl sulfone includes 4,4'-diaminodiphenyl methane. , 3,47-diaminodiphenylsulfone, 33'-diaminodiphenylsulfone, and the like. Lactam compounds include β-propiolactam, γ-
Examples include butyrolactam, γ-halerolactam, δ-valerolactam, ε-caprolactam, and heptolactam.

Examples of alcohols and ketones as dispersion media include methanol, ethanol, 2-methoxyethanol (methyl cellosolve), diacetone alcohol, isophorone, acetone, and methyl ethyl ketone.

Glass cloth epoxy resin laminates, glass cloth/polyimide resin laminates, aluminum core substrates, etc. are used as substrates, and copper foil, etc. that has been bonded in advance may be etched, conductive paste may be printed, or copper, nickel, or silver may be used. A circuit is formed on the board by plating etc. and used. In addition, the substrate is not damaged by dissolution in alcohols, etc., and can be heated at 150℃.
Any material may be used as long as it has the above heat resistance.

The undercoat is applied to avoid as much influence as possible from the underlying substrate, and is formed by printing on the substrate using a predetermined mesh screen or the like and drying it by heating. The same resin as the thermosetting resin used for the organic thick film resistive element is used as the material for the undercoat, but it is not necessarily limited to the same resin. In addition, the drying conditions for the resin are as follows:
The temperature is 120°C to 200°C for about 15 minutes.

The electrodes on the substrate are formed by printing silver conductive paste using a predetermined mesh screen.

In addition, the overcoat after forming the organic thick film resistive element is
It is protected and printed using a designated mesh screen, etc.
Formed by heating and drying. The same resin as the thermosetting resin used for the organic thick film resistance element is used as the material for the overcoat, but it is not necessary to be limited to the same resin. The resin is dried at a temperature of 120° C. to 208° C. for about 15 minutes.

In order to completely cure the undercoat, organic thick film resistive element, and overcoat resin, the substrate was heated to a temperature of 180 to 2
It is heated at 20° C. for about 90 to 180 minutes or more. After sufficiently curing the resin, the substrate is cooled to room temperature, thereby forming an organic thick plate resistive element.

Evaluation Test for Organic Thick Film Resistive Elements Organic thick film resistive elements are evaluated by examining the change in resistance value over time under severe conditions at high temperatures. Note that the temperature of the severe condition is set in consideration of the environmental conditions in which the resistance element is used.

[Examples] Examples of compositions suitable for organic thick film resistive elements according to the present invention will be described below.

(Example 1) Adjustment of carbon paste for organic thick film resistance element 3 and 4 above
．． 3',4'-benzophenonetetracarboxylic dianhydride 3.0 mol, 4,4'-diaminodiphenylsulfone 30 mol and γ-butyrolactam 4 mol methanol and methyl cellosolve as a dispersion medium (1.1 weight ratio) )
(Solid content: 50 wt%). Next, carbon powder was added to
Add 0% by weight to make carbon paste.

Production of Organic Thick Film Resistance Element on a Substrate As shown in FIG. 2, a glass cloth epoxy resin single-sided copper-clad laminate (1.6 mm thick) is used as the substrate 1o. After forming the lead terminal pattern 11 by etching, 1
Dry at 00°C for 10 minutes. An undercoat is printed on the substrate using a 250-mesh screen (emulsion: polyvinyl alcohol), and the undercoat layer 150 has 1
Dry at 20°C for 15 minutes. The undercoat material used is the same as the mixed resin described above.

On the undercoat layer, silver electrodes made by mixing 89 wt % silver powder into the mixed resin are printed using a 250 mesh screen to form electric fi 14 on the substrate. The substrate is dried at 120'C for 115 minutes. The carbon paste 16 is printed between the electrodes and lead terminals of the substrate using a 250 mesh screen and dried for 115 minutes at 150'C to form an organic thick film resistive element. An overcoat was printed on the organic thick film resistive elements (10 pieces with different shapes) using a 250 mesh screen, and the overcoat layer was dried at 150° C. for 15 minutes.

Next, in order to completely cure the resin on the board, the board was
0 part is heated and cured at 3° C. for 5 hours. After heating and curing, it is cooled to room temperature and used as a sample.

The organic thick film resistance element on the substrate has a resistance value of 11Ω/hole (average value of 10 pieces).

The carbon of the organic thick film resistance element on the substrate was placed under severe conditions at a temperature of 150° C., and the change in resistance value over time (hr) was investigated.

As shown in FIG. 2, this organic thick film resistance element has a
Almost no change in resistance value was observed even after hours (change rate of 1% or less after 1000 hours).

(Example 2) 3.4,3° 4°-benzophenonetetracarboxylic dianhydride 1.5 mol, 3,4,3°,4゛diphenylsulfonetetracarboxylic dianhydride 1.5 mol, 30 moles of 44-diaminodiphenylmethane and 4 moles of ε-cabralactam were dissolved in a mixture of methanol as a dispersion medium and diacet alcohol 11 (weight ratio) (solid content 50 w).
An organic thick film resistive element was formed in exactly the same manner as in Example 1, except that the mixed resin liquid was used as the mixed resin liquid.

The resistance value obtained at this time was 9.5Ω/mouth. Even after this resistance element was left in a τ atmosphere at 150° C. for 1000 hours, the change in resistance value was less than 1%, with almost no change observed.

[Comparative Example] (Comparative Example 1) Methyl ethyl ketone using 60 parts of BisA epoxy (epoxy equivalent: 460), 70 parts of butylated melamine (Melamine 27 manufactured by Hitachi Chemical, 57 wt% solution in n-butanol), and 1 part of phosphoric acid as a dispersion medium. /butyl carpitol acetate/α-terpineol-1/1/2 (weight ratio) (solid content 50 wt%) was dissolved in a mixed solution (solid content 50 wt%), and a mixed resin liquid was used for undercoat, silver electrode, carbon resistor, and overcoat. An organic thick film resistance element was formed in the same manner as in Example 1, except that the preliminary drying conditions were 120° C. for 15 minutes and the final curing conditions were 180° C. for 90 minutes. The resistance value obtained at that time was 9.4 Ω/mouth.

The same evaluation as in Example 1 was performed. As a result, as shown in FIG. 1, the resistance value gradually changed, and after 1000 hours, the rate of change decreased by 23%.

(Comparative Example 2) 0-Taresol novolac epoxy (epoxy equivalent: 22
0) 60 parts, butylated melamine (Melamine 2 manufactured by Hitachi Chemical)
7, n-butanol 57wt% solution) 70 parts, phosphoric acid 1
1/1/2 of methyl ethyl ketone/butyl carpitol acetate/α terpineol as a dispersion medium (
(weight ratio) was dissolved in a mixed solution (solid content 50 wt%) to make a mixed resin solution, and the undercoat, silver electrode, carbon resistor, and overcoat were pre-dried at 120°C x 15
except that the final curing conditions were 180°C x 90 minutes.
An organic thick film resistance element was formed in the same manner as in Example 1. The resistance value obtained at that time was 10.5 Ω/mouth.

The same evaluation as in Example 1 was performed. As a result, as shown in FIG. 2, the resistance value gradually changed, and after 100 hours, the rate of change decreased by 28%.

(Comparative Example 3) 100 parts of novolac type phenol resin (molecular weight 600) and 1 part of hexamine were dissolved in a mixed liquid of n-butanol/butyl carpitol acetate-1/1 (weight ratio) as a dispersion medium (solid content 50 wt%) The same as Example 1 except that the pre-drying conditions for the undercoat, silver electrode, carbon resistor, and overcoat were 120°C x 15 minutes, and the final curing conditions were 180°C x 60 minutes. An organic thick film resistor element was formed using the method described above.

The resistance value obtained at that time was 9.2 Ω/mouth.

The same evaluation as in Example 1 was performed. As a result, as shown in FIG. 2, the resistance value gradually changed, and after 1000 hours, the rate of change decreased by 35%.

(Comparative Example 4) A resin liquid was obtained by dissolving 100 parts of polyamino bismaleimide (Kelimide 601 manufactured by Mitsui Petrochemical Industries, Ltd.) in 100 parts of N-methylpyrrolitone as a dispersion medium.
A carbon resistor paste was prepared in the same manner as above and screen printed, but the screen emulsion (masking agent) and squeegee were partially dissolved and printing could not be performed successfully.

[Effects of the Invention] As explained above, in the organic thick film resistive element according to the present invention, the thermosetting resin used in the resistive element is a hensifenone-based and phenylsulfone-based tetracarboxylic dianhydride. , diaminodiphenylmethane and/or diaminodiphenylsulfone, and a lactam compound, the change in resistance of the organic thick film resistance element is extremely small even when subjected to long-term heating. Furthermore, the dispersion medium used in forming the organic thick film resistive element can keep the dispersoid in a stable state and will not dissolve or damage the screen emulsion or squeegee.

4. Brief explanation of the drawings FIG. 1 is a cross-sectional view of a substrate on which an organic thick film resistive element based on the composition according to the present invention is formed, and FIG. 2 is a cross-sectional view of an organic thick film resistive element based on the composition according to the present invention. FIG. 3, which is a plan view of the formed substrate, is a characteristic diagram showing the relationship between the rate of change in resistance value at a temperature of 150'C and elapsed time of an organic thick film resistance element based on the composition according to the present invention.

DESCRIPTION OF SYMBOLS 10... Board, 11... Circuit, 12... Undercoat, 14... if 2m, 16... Carphone paste, 18... Overcoat.

Claims (3)

[Claims] (1) Tetracarboxylic dianhydride whose structural formula is ▲There are mathematical formulas, chemical formulas, tables, etc.▼ and/or ▲There are mathematical formulas, chemical formulas, tables, etc.▼ and diaminodiphenylmethane and/or diaminodiphenylsulfone. A composition suitable for an organic thick film resistance element, characterized in that it is constituted by dispersing a thermosetting resin comprising a lactam compound, a thermosetting resin consisting of a lactam compound, and carbon in a dispersion medium of alcohols and/or Kents. (2) The composition according to claim 1, wherein the molar ratio of the lactam compound/tetracarboxylic dianhydride is in the range of 0.3 to 3. (3) The composition according to claim 1, wherein the lactam compound has the structure ▲ which has a mathematical formula, a chemical formula, a table, etc. ▼ and where n is in the range of 1 to 6.