JPS62152101A - Paint for electric resistor - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

[Detailed Description of the Invention] [Field of Industrial Application] The present invention provides a resistance that has stable reproducibility with little variation even when trying to obtain a high 'r [°C] resistance, and has excellent thermal resistance. The present invention relates to a coating material for electrical resistors that exhibits value stability and is used for producing printed resistor elements that can be formed on synthetic resin laminates.

[Prior art]

Conventional carbon-resin resistance coatings consist of a combination of carbon black and/or graphite powder and thermosetting or thermoplastic resins such as phenolic resins, amine resins, epoxy resins, urethane resins, acrylic resins, etc. The resistance value is roughly determined by the mixing ratio of carbon and resin (1Ω to 10Ω).
5Ω).

However, in order to obtain a high electrical resistance value with these combinations, the amount of carbon added to the resin must be extremely small, and the formation of conductive paths made of carbon particles may be significantly affected by the behavior of the resin. become. Therefore, even if a printed resistor element is formed using only these compositions, the fluctuation in the resistance value distribution will be extremely large, and the resistance value stability against heat will also be extremely poor. Does it have a high resistance value and less fluctuation? ffff Although there has been a demand for gas antibody paints, a product that satisfies the needs has not yet been obtained.

[Purpose of the invention]

In the present invention, we conducted research in an effort to obtain a stable high-resistance paint (1001 (Ω~10 I) MΩ) that could not be obtained with conventional resistance paints whose resistance value was determined by the amount of fine carbon powder added to the resin. As a result, by adding an inorganic filler without reducing the mixing ratio of carbon to the resin solid content, it was possible to obtain a high resistance value (100I〈Ω to 100MΩ), with small variations in resistance value distribution, and furthermore, to achieve heat resistance stability. The inventors obtained the knowledge that a paint for gaseous antibodies with good moisture resistance stability can be obtained, and based on this knowledge, they conducted various studies and completed the present invention.

[Structure of the invention]

The present invention combines a resol type phenolic resin and an amine type resin.
This paint for electrical resistors is characterized in that fine powder of carbon black and/or graphite is dispersed in a mixed phenol composed of fat using a solvent, and an inorganic filler is also dispersed at the same time.

The thermosetting resin used in the present invention may include phenolic resins, amino resins, epoxy resins, urethane resins, etc., but a mixed face of resol type phenolic resin and amine resin has excellent moisture and heat resistance. It is known that it shows. As the resol type phenolic resin, all resols such as phenol resol, alkylphenol resol, xylene resin phenol, etc. can be used, but phenol resol with an ammonia catalyst is generally used. On the other hand, as amine resins, N-methylolated resins such as urea resins, melamine resins, and benzoguanamine resins are used, but melamine resins are better from the viewpoint of moisture resistance and high crosslink density, and among them, melamine resins are better because of their compatibility with phenol resols. Generally, it is preferable to use butyl etherified melamine because of its good properties (Japanese Patent Application Laid-Open No. 58-131045
Publication No.).

As for carbon, all general conductive carbons can be used, and carbon blacks with a developed chain structure such as acetylene black or graphite can be used alone or in combination. Also, although it is an inorganic filler,
Insulating paint due to its stable moisture resistance and electrical properties,
In addition to glue, which is often used in resin products related to electronic materials such as moisture-proof coating paints, talc, clay, calcium carbonate, etc. are preferably used. Further, as an antifoaming agent and a coupling agent, recon oil and the like may be used as appropriate.

In addition, the amount of carbon and inorganic filler added is
Carbon is preferably in a range of 71 parts to 15 parts by weight per 100 parts by weight of the resin solids. If it is 15 parts by weight or more, the sheet resistance value will be 10'Ω/mouth or less, achieving the desired high resistance value. On the other hand, if it is less than 4 parts by weight, it becomes impossible to form a conductive path between carbon particles, and the influence of the resin's high insulation properties increases, making it impossible to control the resistance value with the amount of carbon. Not only that, but the sheet resistance value becomes 109Ω/hole or more, making it impossible to obtain the high-resistance paste (105Ω/hole to 108Ω/hole) that is the object of the present invention.Next, regarding inorganic fillers, solid resin minute 100
It is preferably from 20 parts by weight to 200 parts by weight. If it is less than 20 parts by weight, the effect of adding the filler will be almost negligible, and the resistance value will vary widely and reproducibility will not be obtained.

Moreover, if it exceeds 200 parts by weight, the moisture resistance of the paint will deteriorate and the coating workability will also deteriorate, making it unsuitable for practical use.

〔Effect of the invention〕

By using the paint for electrical resistors having the composition according to the present invention, when trying to obtain a printed resistance element that requires a particularly high resistance value, it is possible to obtain a stable resistance value with much less variation than before. Obtained with good reproducibility.

Therefore, when directly mounting a copper foil (mount part) on a synthetic resin laminate, such as COD (chip-on-board), a high-resistance printed resistor element is used to connect the mount part and other electrodes. It is now possible to use it as a low resistance Sφ resistor to prevent static electricity by connecting it to prevent damage to the JC due to static electricity.

〔Example〕

Example Luzole type phenolic resin (Sumilight Resin PR-51
833, r (C: 65%, manufactured by Sumitomo Durez ■) 66 parts by weight butyl etherified melamine resin (Super Beckamine L-117-708, RC Nia 0%, Dainippon Ink ■
) 30 parts by weight Catalyst (Katanit P, manufactured by Nitto Chemical) 4 parts by weight Carbon black (acetylene black) 3.5 parts by weight Talc (L-1, manufactured by Shiraishi Kogyo ■) 20 parts by weight Butyl cellosolve
101 parts by weight was weighed out and stirred and mixed for 20 minutes using three rolls for ink kneading to produce a paste-like carbon resistance paint. Next, this paint was applied by screen printing to a circuit pattern on a synthetic resin laminate prepared in advance, and cured at 180° C. for 60 minutes to produce a circuit board with a resistor.

The obtained resistance element exhibited a resistance of 7.8 MΩ, and the variation was within the range of approximately +14%, and the variation in resistance value was small despite the high resistance. Further, the measurement result after performing PCT (Pressure Couple Test) at 125° C. for 16 hours was 8.3 MΩ, and the rate of change in resistance value was as small as +65%.

Comparative example resol type phenolic resin (PR-51833, R, C
: 65%) ioo parts by weight Carbon black 3.5 parts by weight Graphite 2 parts by weight Solvent
27 parts by weight The resistance value of this paint was measured in the same manner as in the example, and after curing it was found to be from 0.76 MΩ to 4
There was a large variation between -0 MΩ, and the rate of change after PCT treatment exceeded 20%, which was not practical.

Claims (2)

[Claims] (1) Carbon black and/or
Or, by dispersing fine graphite powder using a solvent,
A paint for electrical resistors, characterized in that it also contains an inorganic filler dispersed therein. (2) The mixing ratio of resin solid content and carbon black and/or graphite (resin solid content/carbon black and/or graphite amount) is 100/4 to 10
0/15 and the mixing ratio of resin solid content and inorganic filler (resin solid content/inorganic filler amount) is 100/20 to
100/200 range of paint for electrical resistors according to claim (1).