JPH01289201A - Chip resistor and manufacture thereof - Google Patents

Abstract

PURPOSE:To manufacture a high-density electronic circuit by forming a protrusion-shaped external electrode terminal layer on a face which is identical to that of a resistance film. CONSTITUTION:A protrusion-shaped external electrode terminal layer 13 is formed on the surface of a primary electrode terminal layer 10; as a method to form this layer, e.g., a metal glaze-based conductor paste composed of silver or silver-palladium, a glass frit and a resin binder is coated to be thick on the surface of the primary electrode terminal layer 10 composed of silver- palladium and of a sintered substance of glass. After this assembly has been fired at a temperature which is lower than a firing temperature of a resistance film 11, the protrusion-shaped external electrode terminal layer 13 is formed. By this setup, when this resistance is mounted on a printed-circuit board by means of a so-called face-down system where the side of the resistance film 11 is faced downward, a high-density electronic circuit can be realized.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of Industrial Application The present invention relates to a chip resistor used in a wide variety of electronic devices and a method for manufacturing the same.

BACKGROUND OF THE INVENTION In recent years, as demands for smaller electronic devices and higher performance have increased, the demand for chip resistors has increased significantly.

The conventional chip resistor has the structure shown in Figure 3.
In FIG. 3, 1 is an insulating substrate, 2 is a primary electrode terminal layer,
3 is a resistive film, 4 is an insulating protective film, and 5 is an external electrode layer.

Such a conventional chip resistor usually has a resistive film 3 made of a fused ruthenium oxide and glass on one main surface of an insulating substrate 1 made of ceramic such as alumina;
An insulating protective film 4 made of glass is provided on its surface, and a primary electrode terminal layer 2 made of a sintered body of silver-palladium and glass is provided at both opposing ends of the resistive film 3, and furthermore, both side wall surfaces of the insulating substrate 1 are provided. An external electrode layer 5 made of a sintered body of silver or silver-palladium is provided in a U-shape over a part of the back surface of the insulating substrate 1.

The external electrode layer 5 is coated with nickel and the outermost layer is a solder metal layer by barrel plating to provide an electrode structure with excellent solderability.

When such a chip resistor is mounted on a printed wiring board, the mounting structure will be as shown in FIG.

In FIG. 4, 6 is a printed wiring board, 8 is a circuit conductor layer, and 8 is a solder metal layer.

Problems to be Solved by the Invention However, in such a chip resistor, the external electrode layer 5 for connection to the printed wiring board 6 is connected to a pair of opposing ends of the rectangular insulating substrate 1 on which the resistive film 3 is formed. Since the external electrode layer 6 is formed in a U-shape along the side wall surface, it is necessary to go through an extremely complicated process to form such an external electrode layer 6, which results in a lack of productivity, making it difficult to reduce the price. It is difficult to measure, and when such a chip resistor is mounted on a printed wiring board 6 and connected by soldering, it is necessary to have a large soldering area for the circuit conductor layer 7 of the printed wiring board 6. There was a disadvantage that it was difficult to increase the density of the material.

The present invention solves these drawbacks of the conventional example and provides a chip resistor that is economical and suitable for high density.

Means for Solving the Problems In order to solve this problem, the present invention has a resistive film on at least one main surface of an insulating substrate, and a pair of opposing ends on the same surface as the resistive film. This structure includes an external electrode layer that protrudes beyond the resistive film.

Function In this way, by configuring the external electrode layer of the chip resistor with protrusions only at both ends of the pair on the same surface as the entire resistive film, it is possible to realize a chip resistor that is inexpensive and suitable for high density. Become.

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

FIG. 1 is a sectional view of a chip resistor in a first embodiment of the present invention.

In FIG. 1, 9 is an insulating substrate, 10 is a primary electrode terminal layer, 11 is a resistive film, 12 is an insulating protective film, and 13 is a protruding external electrode layer.

Examples of the chip resistor having the above configuration will be described in detail below.

In the first embodiment of the present invention, silver, scissor palladium, glass frit, and a resin binder are placed on one main surface of an insulating substrate 9 made of ceramic such as alumina, which is snap-processed so that it can be easily divided into rectangular shapes. The primary electrode terminal layer 10 was formed by applying a mixed conductive paste in a predetermined pattern using a screen printing method or the like and firing it at a high temperature of 800 to 900°C.

Next, a resistor paste made of ruthenium oxide, glass frit, and a resin binder is applied in a pattern to obtain a predetermined resistance value by the same screen printing method so that both ends are in contact with this secondary electrode terminal layer 10.
The resistive film 11 was formed by firing at a high temperature of 00°C. In this case, the resistive film 11 and the primary electrode terminal layer 10 formed at both ends thereof can be formed in large numbers on the main surface of the insulating substrate 9 made of alumina.

A large number of resistive films 111c formed on the main surface of the insulating substrate 9 made of alumina are laser trimmed so that each has a predetermined resistance value, and then a glass paste is applied to the surface and heated to a temperature of 600 to eoo°C. An insulating protective film 12 was formed by firing the film.

Next, a protruding external electrode terminal layer 13 is formed on the surface of the terminal layer 100. In this embodiment, the protruding external electrode terminal layer 13 is formed on the surface of the primary electrode terminal layer 1o made of a sintered body of silver-palladium and glass. Furthermore, a metal glaze-based conductor paste consisting of silver or silver-palladium, glass frit, and a resin binder is applied thickly, and this is fired at a temperature lower than the firing temperature of the resistive film 11 (500 to 600°C) to form protrusions. An external electrode terminal layer 13 was formed.

In this case, the thickness of the protruding external electrode terminal layer 13 is the same as that of the resistive film 1.
The thickness is 30 to 60 μ compared to the 0 to 20 μ, and the surface is coated with metal such as nickel or copper by electroless plating or electroplating to improve solderability, and the outermost layer is coated with metal such as nickel or copper by electroless plating or electroplating. Covered with solder metal.

On the other hand, in another example, as a method for forming the protruding external electrode terminal layer 13, a method was also attempted in which a ball-shaped protrusion having corrosion resistance was bonded to the primary electrode terminal layer 1o using a conductive adhesive. .

The insulating substrate 9 made of alumina with a large number of resistive films 11 and protruding external electrode terminal layers 13 formed on the main surface is finally divided into individual pieces to form a chip resistor. Ta.

The chip resistor made in this way was mounted on a printed wiring board 14 using the so-called face-down method with the resistive film 11 side facing downward, as shown in Figure 2, making it possible to realize a high-density electronic circuit. .

In FIG. 2, 14 is a printed wiring board, 16 is a circuit conductor layer, and 16 is a solder metal layer.

Effects of the Invention As is clear from the above explanation, the chip resistor according to the present invention has a structure in which the external electrode terminal layer is formed in a protruding manner on the same surface as the resistive film, so that the chip resistor according to the present invention has a structure in which the external electrode terminal layer is formed in a protruding shape on the same surface as the resistive film. Unlike the U-shaped external electrode terminals that are formed in a U-shape across both ends of a pair of opposing ends and the side wall surface, external electrode terminals are simultaneously protruded at both ends of a pair of opposing resistive films formed in large numbers on an insulating substrate. Since layers can be provided, the electrode formation process can be greatly simplified, and not only can the cost be lowered by improving productivity, but also when this chip resistor is mounted on a printed wiring board using the face-down method, the printed wiring The projecting external electrode terminals of chip resistors can be reliably soldered to the circuit conductor layer without requiring a large soldering area for the circuit conductor layer of the board, making it possible to create high-density electronic circuits. It is of great industrial value.

[Brief explanation of the drawing]

Fig. 1 is a sectional view of a chip resistor according to an embodiment of the present invention, Fig. 2 is a sectional view of a main part of the same chip resistor mounted on a printed wiring board, and Fig. 3 is a sectional view of a chip resistor according to a conventional example. 4 is a sectional view of a main part of the same chip resistor mounted on a printed wiring board. 8...Insulating substrate, 9...Next electrode terminal layer, 1°...Resistance film, 11...Insulating protective film, 12...・Protruding external electrode terminal layer, 13・
...Printed wiring board, 14...Circuit conductor layer, 16...Solder metal layer. Name of agent: Patent attorney Toshio Nakao and 1 other person No. 1
Figure 16-・-1; Nta Metal 1

Claims (2)

[Claims] (1) A resistive film having a predetermined resistance value is provided on at least one main surface of an insulating substrate, and a pair of opposing ends on the same surface as the resistive film have a protruding shape than the resistive film. A chip resistor with an external electrode terminal layer. (2) A large number of resistive films having a predetermined resistance value on at least one main surface of an insulating substrate, and external electrode terminals that are more protruding than the resistive films at both opposing ends of the resistive films. A method for manufacturing a chip resistor, which comprises dividing the insulating substrate into individual pieces after forming layers.