JPS61234504A - Manufacture of circuit board with resistance - 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] Industrial Application Field The present invention relates to a method of manufacturing a circuit board with a resistor.
Specifically, electronic components such as variable resistors and printed circuit boards can be manufactured with high performance and at low cost.

BACKGROUND ART Conventionally, as a method for forming a circuit board with a resistor, it is known that an electrode pattern is formed using silver paint on a paper phenol laminate or a glass epoxy laminate, and a resistor pattern is formed by connecting to the electrode pattern. ing. However, when silver paint is used, silver migration occurs in a high humidity atmosphere, resulting in a short circuit or, in the worst case, a fire caused by overcurrent. In order to improve this drawback, methods are known in which a coating film is formed on the laminate with epoxy resin or melamine resin before forming the electrode pattern using silver paint, or overcoating the electrode pattern with carbon resin paint. . or.

Conductive paints that use gold powder, copper powder, or nickel powder instead of silver paint are known.

Problems to be Solved by the Invention In the conventional example described above, if a coating film is formed with epoxy resin or melamine resin on the laminate before forming the electrode pattern with silver paint, it is difficult to prevent short circuits and fire accidents. In addition, with the method of overcoating the electrode pattern with carbon resin paint, it is extremely difficult both in terms of design and manufacturing to match the electrode pattern and the pattern made of carbon resin paint without any dimensional deviations.・It was actually difficult to apply it to high-density circuit boards with resistors. Furthermore, conductive paints that use gold powder instead of silver paints are extremely expensive, and paints that use copper powder or nickel powder have inferior conductivity compared to silver paints, making it difficult to use powder as a conductive material. Since the surface is easily oxidized, the conductivity fluctuates greatly under various environments, and it is only possible to use it under very limited conditions. Furthermore, when used as a sliding electrode such as a variable resistor, paints using copper powder or nickel powder have the disadvantage that noise is generated during sliding due to surface oxidation.

The present invention solves these problems.

When a high-density circuit board can be obtained with high precision and without problems such as silver migration, and when used as a variable resistor.

The purpose is to ensure a long sliding life.

Means for Solving the Problem In order to solve this problem, the present invention forms a pattern with a carbon resin paint on a synthetic resin substrate with a conductive layer formed on the surface, and connects the pattern with an insulating resist. A pattern is formed, and the conductive layer other than the two patterns is removed by etching or the like, and the insulating resist pattern is removed and connected to the carbon resin pattern to form a resistance pattern.

Function: With this configuration, it is possible to obtain a resistor-equipped circuit board with high precision, no silver migration, and a long sliding life.

EXAMPLE Hereinafter, an example of the present invention will be described based on one drawing.

First, a first example will be explained. In Figure 1,
75 μm thick polyethylene terephthalate film 1
A polyester adhesive was applied thereon and a 9 μm aluminum foil 2 was laminated thereon [see FIG. 1(a)]. Next, using carbon resin paint, screen printing method (
Print a pattern 3 as shown in b), dry and bake at 120°C for 5 minutes, then connect to the pattern 3 and print an insulating resist pattern 4 as shown in (Q),
It was dried at 120°C for 5 minutes. Next, as shown in (d), the aluminum foil 2 other than the pattern 3 and pattern 4 portions is
was removed by chemical etching, and then the insulating resist pattern 4 was removed. Next, as shown in (e), a resistor pattern 5 was formed by connecting to the pattern 3 to obtain a circuit board with a resistor as shown in FIG. In FIG. 2, 21-2 are aluminum foils, 31-3. 5. is a carbon resin pattern. ．． 5□ is a resistance pattern, and carbon resin pattern 31, 3□.

Aluminum foil 2□, 2. between 3□ and film 1. .

23 are formed respectively. Also, patterns 3□ and 3, .
3. The distance between the electrodes was 0.3 mm.

Next, as a second example, copper was vapor-deposited on a polyimide film having a thickness of 50 μm, and a circuit board with a resistor was obtained using the same pattern and method as in the first example.

Next, as a comparative example, a pattern was formed on a paper phenol laminate with a thickness of 0.5 mm using a silver paint using a screen printing method, with a shape pattern combining the carbon resin pattern of the first example and the insulating resist pattern. A resistor pattern was formed by connecting to the pattern, and a circuit board with a resistor was obtained.

Metal terminals 61°, 62.6. [
Refer to Figure 2] is fixed by caulking method, and the electrode pattern 3
．． A metal brush 7 was installed at the corresponding position of 3□. Place each of the above samples in a tank at 40°C and a relative humidity of 90 to 95%, ground the metal terminal 62 to the metal terminal 6°, apply C, 50V, and measure the rate of change in resistance value between the metal terminals 6□ and 61. Measurements were made for up to 1000 hours. The results are shown in FIG.

In the comparative example, silver migration was confirmed using a microscope at the positions of electrode patterns 31 and 32 after 300 hours. Moreover, after 400 hours, the paper phenol laminate was burnt out mainly at the position where the silver migration occurred, and holes were left in the paper phenol laminate. or.

Even when the sample according to the first example was assembled as a variable resistor and the brush was slid 100,000 times, no sliding noise was generated.

Further, the case of the second embodiment was also substantially the same.

The conductive layer formed on the surface of the synthetic resin base [film 1] is made of metals such as Cu, Ni, and A1, Fe, 0.25%, etc. , Na2WO
4, V, O,.

Cry, t SnO, -3b, O,, In, O, -5
Conductive metal oxides such as nO, conductive nitrides such as TiN and TaN, polyacetylene 1. It can be arbitrarily selected from conductive organic substances such as polythenylene. or,
In order to maintain heat resistance characteristics as a circuit board with a resistor, the synthetic resin base is preferably a thermoplastic resin with a melting point of 210° C. or higher or a thermosetting resin with a glass transition point of 60° C. or higher.

Effects of the Invention As described above, according to the present invention, a resistor-equipped circuit board with high precision and no problems such as silver migration can be obtained at low cost, and when used as a variable resistor, a long sliding life can be ensured.

[Brief explanation of the drawing]

The drawings show an embodiment of the present invention, and FIGS. 1(a) to () are explanatory diagrams showing the first type of circuit board with a resistor, FIG. 2 is a plan view of the circuit board with a resistor, and FIG. It is a graph showing the rate of change in resistance value. 1... Film, 2,2□~23... Aluminum foil. 3.3□~3.... Carbon resin pattern, 4...
...Insulating resist pattern, 5,5. ．． 5□...Resistance pattern, 61-6. ...Metal terminal, 7...Metal brush agent Yoshihiro Morimoto Figure 1

Claims (1)

[Claims] 1. A pattern is formed using a carbon resin paint on a synthetic resin substrate with a conductive layer formed on the surface, and a pattern is formed by an insulating resist connected to the pattern, and the conductive layer other than the two patterns is A method of manufacturing a circuit board with a resistor, which comprises removing the layer by etching or the like, removing the insulating resist pattern, and connecting it to the carbon resin pattern to form a resistor pattern. 2. The method for manufacturing a circuit board with a resistor according to claim 1, wherein the synthetic resin substrate is a thermoplastic resin having a melting point of 210°C or higher or a thermosetting resin having a glass transition point of 60°C or higher.