JPH06105643B2 - Method of manufacturing circuit board with resistance - Google Patents

Description

TECHNICAL FIELD The present invention relates to a method for manufacturing a circuit board with resistance,
Specifically, it is possible to manufacture electronic parts such as variable resistors and printed circuit boards with high performance and at low cost.

2. Description of the Related Art Conventionally, as a method for forming a circuit board with a resistor, there is known a method in which an electrode pattern is formed on a paper phenol laminated plate or a glass epoxy laminated plate with silver paint and is connected to the electrode pattern to form a resistance pattern. ing. However, when the silver paint is used, there is a drawback that silver migration occurs in a high humidity atmosphere, which leads to a short circuit accident of the circuit or, in the worst case, an ignition accident due to an overcurrent. In order to improve this drawback, there is known a method of forming a coating film with an epoxy resin or a melamine resin on a laminated plate before forming an electrode pattern with a silver paint, or overcoating the electrode pattern with a carbon resin-based paint. . Also, a conductive paint using gold powder, copper powder, or nickel powder instead of silver paint is known.

Problems to be Solved by the Invention In the above-mentioned conventional examples, when a coating film is formed on the laminated plate with an epoxy resin or a melamine resin before forming an electrode pattern with a silver paint, it is sufficient to prevent a short circuit accident or a fire accident. It is not possible to exert the effect, and in the method of overcoating the electrode pattern with carbon resin-based paint, it is extremely difficult to match the electrode pattern and the pattern with carbon resin-based paint without dimensional deviation, both in terms of design and manufacturing. -It was practically difficult to apply to high density circuit boards with resistors. In addition, the conductive paint using gold powder instead of silver paint is extremely expensive, and the conductivity using copper powder or nickel powder is inferior to silver paint, so Since the surface is easily oxidized, the conductivity varies greatly under various environments, and it can be used only under a limited number of limited conditions. Further, when it is used as a sliding electrode such as a variable resistor, a paint using copper powder or nickel powder has a drawback that noise is generated during sliding due to surface oxidation.

The present invention solves such a problem, and a high-density circuit board can be obtained with high accuracy and without problems such as silver migration, and when it is used as a variable resistor, a long sliding life can be secured. The purpose is to do so.

Means for Solving the Problems In order to solve this problem, the present invention forms an electrode pattern with a carbon resin-based paint on a synthetic resin substrate having a conductive layer formed on the surface thereof, and connects to the pattern to form an upper surface. A pattern is formed by an insulating resist for leaving a conductive layer for fixing the metal terminal, the conductive layer other than the both patterns is removed by an etching method and the insulating resist pattern is removed, and the pattern is connected to the carbon resin pattern. To form a resistance pattern.

Action With this configuration, it is possible to obtain a highly accurate circuit board with resistance without silver migration and a long sliding life.

Example Hereinafter, an example of the present invention will be described with reference to the drawings.

First, the first embodiment will be described. In FIG. 1, a polyester adhesive was applied onto a polyethylene terephthalate film 1 having a thickness of 75 μm and an aluminum foil 2 having a thickness of 9 μm was laminated [see FIG. 1 (a)]. Next, using a carbon resin-based paint, screen printing (b)
Print pattern 3 as shown in, and dry at 120 ° C for 5 minutes.
After baking, the insulating resist pattern 4 is printed by connecting to the pattern 3 as shown in FIG.
It was dried for 5 minutes. Next, as shown in (d), the aluminum foil 2 other than the portions of the pattern 3 and the pattern 4 is removed by a chemical etching method, and then the insulating resist pattern 4 is formed.
Was removed. Next, as shown in (e), the resistance pattern 5 was formed by connecting to the pattern 3 to obtain the circuit board with resistance shown in FIG. In FIG. 2, 2 _{1 to} 2 ₃ are aluminum foils, 3 _{1 to} 3 ₃ are carbon resin patterns, 5 ₁ and 5 ₂ are resistance patterns, and carbon resin patterns 3 ₁ , 3 ₂ , 3 ₃
Aluminum foil 2 ₁ , 2 ₂ and 2 ₃ are formed between the film 1 and the film 1, respectively. The electrode gap between the patterns 3 ₁ and 3 ₂ and 3 ₃ 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 by the same pattern and method as in the first example.

Next, as a comparative example, a pattern was formed by screen printing with silver paint in a shape pattern in which the carbon resin pattern of the first embodiment and the insulating resist pattern were combined on a 0.5 mm thick paper phenol laminate, and the pattern was formed. To form a resistance pattern to obtain a circuit board with resistance.

The metal terminals 6 ₁ , 6 ₂ , 6 ₃ on the aluminum foils 2 ₁ to 2 _{3 of the} circuit boards with resistors of the first example, the second example, and the comparative example obtained in this way are shown in FIG. [See] is fixed by the caulking method, and the metal brush 7 is attached to the corresponding positions of the electrode patterns 3 ₃ and 3 _1.
Was installed. 1000 hours resistance change rate between the metal terminal 6 ₂ and 6 ₃ by applying DC50V to the metal terminal 6 ₃ grounded metal terminals 6 ₂ at each sample 40 ° C. relative humidity 90% to 95% of a bath Was measured up to. The results are shown in FIG.

In the comparative example, silver migration was confirmed by a microscope at the positions of the electrode patterns 3 ₁ and 3 _{2 after} 300 hours. Further, after 400 hours, it was burned out mainly at the position where the silver transfer occurred, and the paper phenol laminate had holes. Even when the sample according to the first embodiment was assembled as a variable resistor and the brush was slid 100,000 times, sliding noise did not occur. The same was true for the second embodiment.

Incidentally, the synthetic resin base [Film 1] conductive layer formed on the surface Cu, Ni, metals such as _{Al, Fe 3 O 4, Na x} WO 3, V 2 O 3, CrO 2, S n O
_{2 -Sb 2 O 3, I n2} O 3 -S n O conductive metal oxides such as _2, TiN, TaN
It is possible to arbitrarily select from conductive nitrides such as, and conductive organic substances such as polyacetylene and polychenylene.
Also, in order to retain the heat resistance as a circuit board with resistance,
The synthetic resin substrate is preferably 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.

EFFECTS OF THE INVENTION As described above, according to the present invention, it is possible to inexpensively obtain a circuit board with a resistor that does not cause a problem such as migration of silver, and a long sliding life can be secured when the circuit board is used as a variable resistor.

[Brief description of drawings]

The drawings show an embodiment of the present invention, FIGS. 1 (a) to (e) are explanatory views showing formal steps of a circuit board with resistance, FIG. 2 is a plan view of the circuit board with resistance, and FIG. It is a graph which shows a rate of change of value. 1 ... film, 2, 2 _{1 ~} 2 ... aluminum foil, 3,3 _{1-3 3} ...
Carbon resin-based pattern, 4: insulating resist pattern, 5,5 _1, 5 ₂ ... resistance pattern, ₆₁ through ₃ ... metal terminal, 7 ...
Metal brush

Claims (1)

[Claims] 1. A pattern made of an insulating resist for forming an electrode pattern on a synthetic resin substrate having a conductive layer formed on the surface thereof with a carbon resin-based paint and leaving a conductive layer for fixing a metal terminal on the upper surface of the electrode pattern. And removing the conductive layers other than the both patterns by an etching method or the like and removing the insulating resist pattern, and connecting to the carbon resin pattern to form a resistance pattern circuit board with resistance. Manufacturing method.