JPH0917609A - Multilayered type chip thermistor - Google Patents

Abstract

PURPOSE: To provide a small-sized multilayered type chip thermistor excellent in performance which has inner electrodes in an element, and a manufacturing method of it. CONSTITUTION: In this multilayered type chip thermistor, inner electrodes 12 are arranged in a thermistor element 11, and heat-resistant insulating films 14 are formed on the surfaces of the thermistor element 11. The following are employed; a process wherein thermistor material sheets and the inner electrodes 12 are alternately laminated and baked, a process wherein glass surfaces are formed on both of the surfaces of a baked object, a process wherein cutting into a strip shape is performed, a process wherein a glass film is formed on the surface of the thermistor element 11 of strip-shaped segment, a process wherein chips are formed by cutting the thermistor element, and a process wherein outer electrodes 13 are formed at both ends of the chip.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a laminated chip thermistor mounted on an electronic device, a printed circuit board or the like and a method for manufacturing the same, and more particularly to a laminated chip thermistor having internal electrodes inside a body and a method for manufacturing the same. Regarding

[0002]

2. Description of the Related Art Conventionally, a laminated chip thermistor having internal electrodes inside a thermistor element body is integrally laminated with a thermistor element body and dried, and then cut to make a chip, which is then baked. Further, after the external electrodes were formed on both end surfaces of the fired product, the electrodes were fired again, whereby the product was manufactured. JP-A-6-53009 JP-A-6-61014

[0003]

However, according to this manufacturing method, since the unfired thermistor element body is cut to manufacture the chip, the resistance value of the fired product varies greatly. Also, because it is cut into chips in the unbaked stage,
Since the element body was soft and the size of the cut pieces and the cutting accuracy were limited, it was difficult to deal with products of 1.0 mm × 0.5 mm or less.

Further, for the purpose of extending the life of the product, even if the thermistor element body is reinforced by coating glass or the like in order to supplement the bending strength of the thermistor element body, the spattering method must be employed because the chip is fine. In that case, the coating was thin and not suitable for practical use.

[0005]

[Means for Solving the Problems] Therefore, in order to solve the problems of the above-mentioned manufacturing method, as a result of various investigations, the thermistor body is not cut into chips into chips, but the thermistor body is baked. It was found that the above problems can be solved by cutting into chips later.

That is, the gist of the present invention is that, in claim 1, 1 to 1 are contained inside the thermistor element body (11).
The thermistor element body has ten layers of internal electrodes (12), and external electrodes (13) are formed on both end surfaces of the thermistor element body.
4) A multilayer chip thermistor characterized by being formed. In the second aspect, a raw material sheet layer (15) formed by laminating a plurality of thermistor raw material sheets and an internal electrode pattern (2) formed on the upper surface of the raw material sheet layer.
1) and 1) are laminated 1 to 10 times, and a raw material sheet layer is laminated on the upper surface thereof to produce a laminate (16); and a heat-resistant insulating film raw material film (17) is formed on both upper and lower surfaces of the laminate. After applying, a step of firing this, a step of cutting the fired product into strips, and a step of applying the heat-resistant insulating film raw material film in the longitudinal direction of the thermistor body surface of the cut strips (18),
The step of firing this again and cutting it
And a step of forming external electrodes on the surface of the thermistor element body surface on which the heat resistant insulating film of the chip is not formed, and a method of manufacturing a laminated chip thermistor.

In the present invention, the number of layers of the internal electrodes is limited to 10 layers, since the thermistor body sandwiched between them is thinned as a result of which the durability of the product is lowered.

The present invention is applied to an NTC thermistor, and the thermistor body is based on an oxide such as Mn, Co, Cu or Fe.

As the internal electrodes, those based on silver or palladium are mainly used.

An external electrode mainly made of silver is used, and a metal plating (20) is applied to the surface of the external electrode in order to improve adhesion with solder or environmental resistance.

The heat-resistant inorganic film is applied to strengthen the die strength of the multilayer chip thermistor itself and to protect the thermistor body from high temperature and corrosive gas under the measurement environment. Alternatively, crystallized glass or the like is optimally used.

[0012]

In the present invention, since the thermistor element body is fired and then cut, a part of the thermistor piece can be sampled after firing and the resistance value thereof can be investigated. Based on this resistance value, the thermistor piece can be examined. Since the cutting length of the chip can be adjusted, a highly reliable product can be obtained. Further, since the thermistor element body having a large area and having been fired is obtained in the intermediate stage of the manufacturing process, it is possible to apply a glass raw material film to this by a printing method, and by firing this, the surface of the thermistor element body Since a coating such as glass can be formed on the surface of the thermistor, the folding strength of the product can be improved and the thermistor body can be protected from the measurement environment.

[0013]

An embodiment of the present invention will be described below with reference to FIG.

In FIG. 1, reference numeral 15 is a raw material sheet.
The material sheets are NTC thermistor material sheets 1 to 10
It is produced by stacking layers and pressure bonding.

An internal electrode pattern (21) is formed on the upper surface of the raw material sheet (15) by a printing method and dried. After drying, a raw material sheet is further pressure-bonded to the upper surface of the internal electrode pattern, which is then dried and fired at a temperature of 1100 ° C. for 5 hours to produce a laminated plate (16).

In this step, after the raw material sheet is pressure-bonded to the upper surface of the internal electrode pattern, the internal electrode pattern is formed on the upper surface, the raw material sheet is further placed, and the internal electrode pattern is formed on the upper surface. By repeating this process, a laminated plate having a plurality of layers of internal electrodes can be obtained.

A glass material film is formed as a heat-resistant insulating film material on both sides of this laminated plate by a printing method, and is baked at a temperature of 850 ° C. for 10 minutes to form a wafer (55 mm × 38 m).
A sintered body of m × 0.45 mm) was obtained. The sintered body was cut into strips using a wet cutting machine. After cutting, a glass film was formed by a printing method on the cross section of the strip-shaped piece in the long-side direction on which the heat-resistant insulating film was not formed, and the glass film was baked at a temperature of 850 ° C. for 10 minutes. The fired product is cut by a wet cutting machine to obtain chips (L1m
m × W0.5 mm × T0.45 mm) was produced.

An electrode material composed mainly of silver was adhered to both end surfaces of the chip on which the glass layer was not formed and was fired again to form external electrodes. Ni plating was formed on the surface of this external electrode by electrolytic plating to produce a multilayer chip thermistor. In this example, the internal electrode was only one layer.

Comparative Example An internal electrode pattern is formed on the upper surface of a raw material sheet by a printing method and dried. After drying, the raw material sheet is further pressure-bonded to the upper surface of the internal electrode, and then dried to form a wafer-shaped product, which is cut into a predetermined length to form a chip-shaped product. This was baked at a temperature of 1100 ° C. for 5 hours. An electrode material composed mainly of silver and palladium was attached to the surface of the thermistor body, dried, and then baked at a temperature of 820 ° C. for 5 minutes to form an external electrode, thereby producing a laminated chip thermistor.

The size of the multilayer chip thermistor manufactured in this comparative example and the structure of the internal electrodes are the same as those in the example.

<Experiment> The following experiment was conducted using the laminated chip thermistor produced in the examples and the comparative examples. [Experiment 1] 100 multilayer chip thermistors produced by the methods of Example 1 and Comparative Example 1 were arbitrarily sampled,
The difference in dimensional variation was investigated. The results are as shown in Table 1.

Table 1 Example 1 Comparative Example 1 Average (mm) Standard Deviation Average (mm) Standard Deviation L 1.002 0.002 0.990 0.015 W 0.501 0.002 0.512 0.023 T 0.450 0.001 0.441 0.050 The variation in Example 1 is smaller. [Experiment 2] 100 multilayer chip thermistors produced by the methods of Example 1 and Comparative Example 1 were arbitrarily sampled and 5
The variation of the resistance value at 0 ° C was examined. Table 2 Example 1 Comparative Example 1 Average (KΩ) Standard Deviation Average (KΩ) Standard Deviation 2.994 0.012 2.853 0.260 Example 1 has less variation.

[0023]

According to the present invention, it is possible to obtain a multilayer chip thermistor which is small in size, has a small fluctuation in resistance value, has a high bending strength, and is excellent in environmental adaptability.

[Brief description of the drawings]

FIG. 1 is a sectional view of one embodiment of the present invention.

FIG. 2 is a cross-sectional view of one embodiment of the present invention.

FIG. 3 is a sectional view of one embodiment of the present invention.

FIG. 4 is a process drawing of an example of a method for manufacturing a multilayer chip thermistor of the present invention.

[Explanation of References] 11 Thermistor body 12 Internal electrode 13 External electrode 14 Heat resistant insulating film 15 Raw material sheet layer 16 Laminated plate 17 Heat resistant insulating film raw material film 18 Strip-shaped piece 19 Chip 20 Metal plating 21 Internal electrode pattern

Claims (2)

[Claims] 1. A thermistor element body (11) is formed with 1 to 10 layers of internal electrodes (12), and external electrodes (13) are formed on both end surfaces of the thermistor element body. A laminated chip thermistor characterized in that a heat-resistant insulating film (14) is formed on the surface without electrodes. 2. A raw material sheet layer (15) formed by laminating a plurality of thermistor raw material sheets, and an internal electrode pattern (21) formed on the upper surface of the raw material sheet layer.
Or 10 times, and a step of producing a laminate sheet (16) by laminating a raw material sheet layer on the upper surface thereof, and applying a heat resistant insulating coating raw material film (17) on the upper and lower surfaces of the laminate sheet, and then baking the same. And a step of cutting the fired product into strips,
A step of applying a heat-resistant insulating film raw material film in the longitudinal direction of the thermistor body surface of the cut strip-shaped piece (18), and then firing the same again; and a step of cutting this and manufacturing a chip (19). And a step of forming an external electrode on the surface of the thermistor body on which the heat-resistant insulating film of the chip is not formed, the method of manufacturing a multilayer chip thermistor.