JPH06132101A - Square chip resistor - Google Patents

Abstract

PURPOSE:To provide a precision, rectangular chip resistor including a thick-film resistance element and rigid electrodes, which can be produced at a high yield. CONSTITUTION:The rectangular chip resistor consists of a pair of upper electrode layers 12 formed on the principal plane of an alumina substrate 11, thick film resistor 13 formed between the upper electrode layers 12 and overlapping them, protective film 14 formed to cover the thick film resistor 13 completely, and a pair of thin film end face electrode layers 15 covering from the top to the bottom of both ends of the alumina substrate 11 and overlapping the upper electrode layers 12.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates generally to a precision grade rectangular chip resistor used in electronic circuits.

[0002]

2. Description of the Related Art In recent years, with the reduction in weight and size of electronic equipment, there is an increasing demand for surface mounting components in order to increase the mounting density of electronic components used for circuit boards. Also for resistors, as a substitute for the semi-fixed volume that has been used conventionally, there is an increasing demand for chip resistors with higher resistance value accuracy.

As shown in FIG. 3, a conventional chip resistor has a pair of silver-based thick film glaze upper surface electrode layers 2 formed on a heat-resistant insulating substrate 1 made of a high-purity alumina substrate or the like, and A ruthenium oxide-based thick film glaze resistor 3 formed between a pair of upper electrode layers 2, a resin-based or thick film glaze glass-based protective film 4 formed so as to completely cover the resistor 3, and An end surface electrode layer 5 formed of a pair of resin-based thick films respectively formed from the end surfaces on both sides of the insulating substrate 1 to the back surface so as to partially overlap the upper surface electrode layer 2, and the upper surface electrode layer 2 and the end surface electrode layer 5 are exposed. It was composed of a plating layer 6 plated with Ni and solder in order to enable soldering on the above portion.

[0004]

However, in the conventional chip resistor, the accuracy of the resistance value obtained by the resistance value correction by laser trimming, etc. is a thick film in the manufacturing process in which the protective film and the end face electrode layer are later baked at a high temperature. The resistor was deteriorated by being affected by heat, and the yield in the manufacturing process was deteriorated. For this reason, the protective film and the end face electrode layer do not use thick film glaze-based material of high temperature baking (having a softening point of about 600 ° C.), and are relatively low temperature (temperature of 150 to 200 ° C.).
It was generally formed of a resin-based material that is cured by. However, when the end face electrode layer is formed of such a resin-based material, there is a problem that the electrode strength is inferior to that when the end face electrode layer is formed of a thick film glaze-based material.

In order to solve the above problems, it is an object of the present invention to provide a rectangular chip resistor made of a thick film resistor having a high electrode strength without deteriorating the yield.

[0006]

In order to achieve the above object, a prismatic chip resistor according to the present invention has a pair of upper surface electrode layers formed on the main surface of an insulating substrate and a pair of upper surface electrode layers. A thick film resistor formed between the upper surface electrode layers so that the portions overlap, a protective film formed so as to completely cover the thick film resistor, and an insulating substrate so as to partially overlap each of the upper surface electrode layers. It is formed from both end faces to the back face, and is provided with a pair of thin film end face electrode layers formed by a sputtering method, an ion plating method or a vacuum deposition method.

[0007]

According to the present invention, since the resistance value accuracy obtained by the resistance value correction does not affect the thick film resistor in the subsequent manufacturing process, the yield strength is not deteriorated and the electrode strength is high. A precision square chip resistor can be provided.

[0008]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A rectangular chip resistor according to an embodiment of the present invention will be described below with reference to the drawings.

FIG. 1 is a sectional view showing a rectangular chip resistor according to an embodiment of the present invention, and FIG. 2 is a manufacturing process diagram of the rectangular chip resistor of FIG.

As shown in the figure, the rectangular chip resistor of the present invention has a pair of silver-palladium-based thick films on the main surface of an alumina substrate 11, which is a rectangular plate-shaped insulating substrate excellent in heat resistance and insulation. The electrode layer 12 is formed, and the upper surface electrode layer 1 is formed so as to partially overlap each of the pair of upper surface electrode layers 12.
A thick film resistor 13 made of ruthenium oxide glaze is formed between the two. Further, a thermosetting resin type protective film 14 is formed so as to completely cover the thick film resistor 13, and the upper surface electrode layers 12 are partially overlapped with each other from the end surface to the back surface on both sides of the alumina substrate 11, respectively. Ni
A pair of thin film end face electrode layers 15 formed by sputtering a system material are formed. Further, the exposed upper surface electrode layer 12 and the thin film end surface electrode layer 15 are plated with Ni, Sn—Pb by electrolytic plating in order to prevent electrode erosion during soldering and ensure reliability during soldering. Forming layer 6.

When the electrode strengths of the rectangular chip resistor of the present invention constructed as above and the conventional rectangular chip resistor are compared, the rectangular chip resistor of the present invention has a stronger electrode strength.

In general, as a chip resistor having a high resistance value accuracy, there is a thin film chip resistor in which a resistor is formed of a thin film material. However, when used in an electronic circuit, a chip resistor having only a high resistance value accuracy is used. If a resistor is needed (the temperature coefficient of resistance does not have to be small), the rectangular chip resistor according to the invention is cheaper.

Further, in this embodiment, the protective film is
Since it is made of a resin material that is thermoset at 50 to 200 ° C., it does not affect the thick film resistor thermally.
The yield of resistance value accuracy is not deteriorated.

Further, in the present invention, the protective film is made of a resin material, but when high reliability (particularly moisture resistance) is required, it is made of, for example, a lead borosilicate-based high temperature glass material. . Even in that case, if the end face electrode layer is formed by sputtering a Ni-based material and the end face electrode layer is formed by a thin film, the chip resistance having a stronger electrode strength than that formed by the conventional thick film glaze material. It was confirmed that a container was obtained.

Although the thin film end face electrode layer is formed by the sputtering method in this embodiment, the same effect can be obtained by forming it by the ion plating method or the vacuum deposition method.

[0016]

As described above, according to the present invention, since the end face electrode layer is formed into a thin film by the sputtering method, the ion plating method or the vacuum deposition method without applying heat at high temperature, a thick film resistor is formed. Since there is no heat influence, the yield of resistance value accuracy is not deteriorated, and a precision chip resistor having an electrode strength equal to or higher than the electrode strength when the end face electrode layer is formed by a thick film glaze can be realized.

[Brief description of drawings]

FIG. 1 is a sectional view showing a rectangular chip resistor according to an embodiment of the present invention.

FIG. 2 is a manufacturing process diagram of a rectangular chip resistor according to the embodiment.

FIG. 3 is a sectional view showing a conventional rectangular chip resistor.

[Explanation of symbols]

 11 Alumina substrate 12 Upper surface electrode layer 13 Thick film resistor 14 Protective film 15 Thin film end surface electrode layer

Front page continuation (72) Inventor Tomio Inoue 1006 Kadoma, Kadoma City, Osaka Prefecture Matsushita Electric Industrial Co., Ltd.

Claims (2)

[Claims] 1. A pair of upper surface electrode layers formed on a main surface of an insulating substrate, a thick film resistor formed between the upper surface electrode layers so as to partially overlap each of the pair of upper surface electrode layers, and a thickness of the thick film resistor. The protective film is formed so as to completely cover the film resistor, and the insulating film is formed so as to partially overlap with each of the upper surface electrode layers from both end surfaces to the rear surface of the insulating substrate, and the sputtering method, the ion plating method or the vacuum evaporation method is used. Rectangular chip resistor having a pair of thin film end face electrode layers formed by the method. 2. The rectangular chip resistor according to claim 1, wherein the protective film is formed of a thermosetting resin.