JPS5910769Y2 - Flexible circuit board with resistor - Google Patents

Description

[Detailed Description of the Invention] The present invention relates to a flexible circuit board with a resistor, and particularly to a flexible circuit board such as a variable resistance circuit board in which the resistor pattern is concentrated in a certain part. It's about structure.

Flexible circuit boards can be bent, folded, stacked, and wrapped, and are thin and lightweight, so they have various advantages over rigid circuit boards. New possibilities have arisen in circuit design, such as reduced wiring, smaller space requirements, and improved functionality.

However, in conventional flexible circuit boards, what is formed on the flexible circuit board itself is limited to the conductor pattern of the electric circuit. It was possible to integrally form the conductor pattern with the conductor pattern on the circuit board.

This is because while the copper foil and aluminum foil used for conductor patterns are extremely flexible, most of the materials used for resistors (patterns) used in film shapes are either rigid or not very flexible. This is because the resistor is not very flexible or is very thin, so the characteristics of the resistor change when the flexible support is bent, and the resistor is easily damaged.

Therefore, the resistor pattern is generally formed directly onto a rigid substrate such as a ceramic plate by printing, vapor deposition, etc. However, since this conventional method is difficult to perform continuously, the inventor of the present invention JP-A-5281560 previously proposed a method in which a resistor pattern is formed on a flexible heat-resistant insulating sheet and then a rigid substrate is fixed on the entire surface of the sheet. It was intended for plates and was not flexible.

For this reason, conventionally, when manufacturing electric circuits, individual resistive elements were inserted into a prefabricated flexible conductor circuit board and soldered, or by soldering to a circuit board with a rigid resistor. A method of connecting was used.

Mounting resistance elements on flexible conductor circuit boards and connecting them to rigid resistor circuit boards by soldering is very complicated.
It is a process that requires manpower, and requires soldering connections that are essentially unnecessary on the circuit, which poses problems in terms of space and material costs. Restrictions arise on top and circuit pattern placement.

Furthermore, it is said that the majority of failures in electrical equipment are caused by disconnections in soldered parts.

The flexible circuit board with a resistor according to the present invention can solve all of the above-mentioned problems, and has a flexible insulating support and an electric circuit conductor integrally formed on the support. In a flexible circuit board consisting of a pattern and a resistor pattern, a bend-resistant backing plate is bonded to the resistor pattern and its surrounding area to reinforce the resistor pattern and its surrounding area and to protect the resistor pattern. It is characterized by having a function added to it, and is characterized by a flexible circuit board in which a resistor pattern is concentrated in a certain area, such as a resistor pattern for a variable resistor, or an individual resistor element is placed in one place or It is particularly useful for applications in flexible circuit boards having resistor patterns concentrated in several fixed areas.

As the flexible insulating support used in the present invention, flexible insulating sheets or films such as polyester, polyimide, polyamideimide, flexible epoxy resin-glass cloth, and flexible epoxy resin paper can be used. The conductor pattern (including electrodes) is made of copper foil, aluminum foil, gold or tin-plated copper foil, zinc foil, lead foil, conductive printing paste, or the like.

As the material for the resistor pattern, thin films of noble metals such as gold, silver, and platinum and alloys such as nickel-tin and nickel-tin, carbon-resin pastes, metal resin pastes, and some pastes for thick film resistors are used.

Therefore, in order to obtain a flexible circuit board by integrally forming a conductor pattern for an electric circuit and a resistor pattern on a flexible insulating support, a thin film of a resistor and a resistor pattern are formed on the insulating support. After forming the conductive foil, the thin film and the foil are photo-etched into a desired shape to form both patterns, or after printing and baking the resistor paste on the insulating support, a conductive printing paste is applied. This can be done by a known method such as applying the powder to form the desired pattern.

The present invention is characterized in that a bend-resistant backing plate is bonded to the resistor pattern and the surrounding area of the flexible circuit board to partially reinforce the resistor pattern and provide a protection function for the resistor pattern. The bend-resistant plate is made of a material that completely prevents the resistor pattern from bending, such as thick plastic plates, fiber-reinforced plastic plates, various laminated plates, metal plates, etc., processed into small pieces. It will be done.

After the conductor pattern and the resistor pattern are formed on the flexible insulating support, this plate is bonded to the back side of the circuit board (insulating support side), or the resistor pattern is formed on the back side of the circuit board. It may be joined in advance at the corresponding position before being attached.

Further, when the backing plate is bonded after the resistor pattern is formed, it may be bonded to the front surface side of the circuit board (the side where the resistor pattern is present).

An example of a flexible circuit board with a resistor according to the present invention will be described below with reference to the drawings.

Figures 1 and 2 show aspects of the circuit board for variable resistance.
A resistor pattern 2 for variable resistance and a conductor (including electrode) pattern 3 are formed on the surface of the flexible insulating support 1 to form a flexible circuit board. A bend-resistant backing plate 5 is bonded to the back surface of the resistor pattern and its surrounding portion 4 to provide a protection function for the resistor pattern.

Since the present invention is structured as described above, it has the following excellent effects and usefulness.

(1) The characteristics of the resistor pattern can be maintained stably for a long period of time,
The conductor pattern in the non-bonded portion of the contact plate can fully utilize its inherent flexibility.

(2) By concentrating the resistor pattern on a certain part of the flexible circuit board and using a bend-resistant backing plate,
It is now possible to place a resistor on a flexible circuit board with a resistor, which was previously difficult to put into practical use due to unstable characteristics.
A novel circuit board with resistors that is substantially flexible is obtained.

(3) The conventionally required space for connecting the flexible conductor circuit board and the resistance element is no longer required, and space and material costs can be significantly reduced.

(4) Since the above-mentioned solder connection part is eliminated, failures caused by disconnection in that part essentially do not occur, and reliability is improved.

(5) There is no need to consider layout to facilitate soldering, and the degree of freedom in design increases.

(6) Continuous production of flexible circuit boards with resistors becomes possible.

[Brief Description of the Drawings] Fig. 1 is a plan view showing an example of a flexible circuit board with a resistor of the present invention, and Fig. 2 is a plan view taken along the line I-I' in Fig. 1 and viewed from the direction of the arrow. A cross-sectional view is shown. 1... Flexible insulating support, 2... Resistor pattern, 3... Conductor (including electrode) pattern, 4... Resistor Pattern and its surrounding area, 5...Bending-resistant backing plate.

Claims (2)

[Scope of utility model registration request] (1) In a flexible circuit board consisting of a flexible insulating support, a conductor pattern of an electric circuit formed on the support, and a resistor pattern, the resistor pattern and its surrounding area are provided with bending resistance. A flexible circuit board with a resistor, which is formed by bonding a backing plate to reinforce the resistor pattern and its surrounding area and to provide a protection function for the resistor pattern. (2) A flexible circuit board with a resistor according to claim 1, wherein the resistor pattern is concentrated in a certain portion of the circuit board.