JP2001143904A - Composite laminate thermistor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a composite laminate thermistor which can contribute to miniaturization of an electronic apparatus using a plurality of thermistors such as a temperature compensation circuit of a crystal resonator. SOLUTION: Outer electrodes 4a, 4b, 4c are formed on the exposed end surfaces of inner electrodes 3a, 3b, 3c, 3d of a laminate, in which a first thermistor layer 1, an inner electrode layer 3a, a first thermistor layer 1, an inner electrode layer 3b, a first thermistor layer 1, a second thermistor layer 2, an inner electrode layer 3c, a second thermistor layer 2, an inner electrode layer 3d, and a second thermistor layer 2, are laminated in this order. Resistivity of the first thermister layer 1 is higher than that of the second thermistor layer 2. The inner electrode layers 3b, 3c are connected with the outer electrode 4a, on the same end surface. The inner electrode 3d is connected with the outer electrode 4b, on the end surface facing the inner electrode layers 3b, 3c. The inner electrode layer 3a is connected with the outer electrode 4c, on one side surface different from both exposed end surfaces of the inner electrode layers 3b, 3c, 3d.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a composite laminated thermistor used for temperature compensation of a crystal oscillator or the like.

[0002]

2. Description of the Related Art In a temperature compensation circuit for a crystal oscillator used in a portable telephone as shown in FIG. 12, two thermistors are used.
The other thermistor 10 for temperature compensation in the low temperature range of 25 ° C.
No. 1 is used for temperature compensation in a high temperature range of 25 to 85 ° C.

[0003] These thermistors 100 and 101 are shown in FIG.
As shown in FIG. 3, the thermistor layer 110 and the internal electrode layer 111
The external electrodes 112 are formed on both end surfaces of the laminate in which the electrodes are alternately connected, and are separately mounted on the substrate.

[0004]

According to this configuration, there is a problem that the mounting area is large and it is not possible to contribute to miniaturization of electronic equipment such as a portable telephone.

Accordingly, an object of the present invention is to provide a composite laminated thermistor which can contribute to miniaturization of electronic equipment using a plurality of thermistors such as a temperature compensation circuit of a crystal oscillator.

[0006]

In order to achieve this object, a composite laminated thermistor according to the present invention comprises at least a laminated thermistor having external electrodes formed on the surface of a laminate in which thermistor layers and internal electrode layers are alternately laminated. In the two-layer composite thermistor, each of the laminated thermistors is formed by thermistor layers having different specific resistances, and the composite laminated thermistor has at least two thermistor characteristics with one composite laminated thermistor, so that the above object can be achieved. .

[0007]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The invention according to claim 1 of the present invention is a composite in which at least two laminated thermistors having external electrodes formed on the surface of a laminate in which thermistor layers and internal electrode layers are alternately laminated. In the multilayer thermistor, each of the multilayer thermistors is a composite multilayer thermistor formed by thermistor layers having different specific resistances, has a plurality of thermistor characteristics, and is mounted in an electronic device in which a plurality of thermistors are conventionally mounted. The area can be reduced and the number of parts can be reduced.

According to a second aspect of the present invention, there is provided the composite according to the first aspect, wherein one of the external electrodes of the multilayer thermistor having a high specific resistance is formed on a surface different from the surface on which the external electrodes of the multilayer thermistor having a low specific resistance are formed. It is a laminated thermistor, and can easily integrate thermistors having different specific resistances.

According to a third aspect of the present invention, there is provided the composite laminated thermistor according to the first aspect, wherein an insulating layer is provided between the laminated thermistors. Is a laminated thermistor having the following characteristics.

According to a fourth aspect of the present invention, there is provided the composite laminated thermistor according to the first aspect, wherein a shield electrode layer connected to the same external electrode as the internal electrode layer adjacent between the laminated thermistors is provided. Mutual diffusion between the laminated thermistors is suppressed, and the laminated thermistors each have desired characteristics.

Hereinafter, embodiments of the present invention will be described with reference to the drawings.

(First Embodiment) FIG. 1 is a perspective view of a composite laminated thermistor according to a first embodiment of the present invention, and FIG.
FIG. 3 is a sectional view taken along line AB of FIG. 1, and FIG.
Is a first thermistor layer, 2 is a second thermistor layer, 3a, 3
b, 3c and 3d are internal electrode layers, and 4a, 4b and 4c are external electrodes. The first thermistor layer 1 has a higher specific resistance than the second thermistor layer 2.

FIG. 4 is an exploded perspective view of the laminated body of the composite laminated thermistor shown in FIG. 1, wherein 10 is a first green sheet, 11 is a second green sheet, and 12a, 12b, 1
2c and 12d are electrode pastes containing Pd as a main component.

First, as the first thermistor layer 1, Mn: C
o: Fe: Al = 32.5: 50: 10: 7.5 atomic%
The first green sheet 10 having a thickness of 30 μm is prepared by a doctor blade method using a raw material having a ratio.

The second thermistor layer 2 is formed of Mn: N
A similar second green sheet 11 is manufactured using a raw material having an atomic percentage ratio of i: Cu = 68: 23: 9.

Next, as shown in FIG. 4, a plurality of first green sheets 10 are laminated and pressed, and an electrode paste 12a is printed so as to form the internal electrode layer 3a.

Next, the first green sheet 10 is laminated and pressed on the electrode paste 12a, and the electrode paste 12b is printed so as to form the internal electrode layer 3b.

Subsequently, a plurality of first green sheets 10 and a plurality of second green sheets 11 are laminated and pressed on the electrode paste 12b in this order.

Next, after the electrode paste 12c to be the internal electrode layer 3c is printed on the second green sheet 11, the second green sheet 11 is laminated and pressed.

Next, after an electrode paste 12d to be the internal electrode layer 3d is printed on the second green sheet 11,
A plurality of green sheets 11 are laminated and pressed to obtain a laminated green block.

Thereafter, the laminate green blocks are cut to obtain a large number of laminates.

This laminate is fired at 1150 ° C. in the air to obtain a sintered body, which is then chamfered to form the internal electrode layers 3a, 3a.
b, 3c and 3d are exposed on the end face of the sintered body.

In this sintered body, the internal electrode layers 3b, 3
c and 3d are formed between the first thermistor layers 1 with one end exposed at the opposing end faces of the sintered body, and the internal electrode layer 3b closest to the second thermistor layer 2 and the second thermistor layer 2 and is exposed on the same end face so as to be connected to the same external electrode 4a as the internal electrode layer 3c closest to the first thermistor layer 1. The internal electrode layer 3d is exposed at a different end face.

Further, the internal electrode layer 3a includes the internal electrode layer 3b,
It is exposed on one side surface of the sintered body different from the exposed both end surfaces of 3c and 3d.

Next, the exposed side surfaces of the internal electrode layer 3a of the sintered body and the exposed end surfaces of the internal electrode layers 3b, 3c, 3d
The electrode paste containing g as a main component is applied and baked at 800 ° C. to form the external electrodes 4a, 4b, and 4c.

Thereafter, a nickel film (not shown) is formed on the external electrodes 4a, 4b, 4c by electrolytic plating, and a solder film (not shown) is further formed thereon, and the composite laminated thermistor shown in FIG. 1 is formed. Obtained.

In this composite laminated thermistor, the resistance generated between the external electrodes 4a and 4b opposed to each other across the multilayer body is the resistance generated between the internal electrode layers 3a and 3b and the resistance generated between the internal electrode layer 3c and the external electrode 4b. This is the parallel resistance of the resistors. However, since the specific resistance of the second thermistor layer 2 is smaller than the specific resistance of the first thermistor layer 1, the internal electrode layer 3c
Between the internal electrode layers 3a and 3b.
This is very large as compared with the resistance generated between b. Therefore, the resistance generated between the external electrodes 4a and 4b is substantially equal to the resistance generated between the internal electrode layers 3a and 3b,
The B constant is substantially equal to the B constant of the first thermistor layer 1.

The external electrode 4c provided on a different surface of the laminate from the external electrodes 4a and 4b is formed only on the surface of the first thermistor layer 1 and is not formed on the surface of the second thermistor layer 2. Thus, the resistance generated between the external electrodes 4a and 4c is equal to the resistance generated between the internal electrode layers 3c and 3d, and the B constant is equal to the B constant of the second thermistor layer 2.

For comparison, in the conventional laminated thermistor shown in FIG.
o: Fe: Al = 32.5: 50: 10: 7.5 atomic%
A first laminated thermistor formed by using a material having a ratio and a thermistor layer 101 are formed by Mn: Ni: Cu = 68:
A second laminated thermistor formed using a raw material having an atomic ratio of 23: 9 was manufactured.

The composite laminated thermistor according to the first embodiment,
The results obtained by immersing the two types of conventional laminated thermistors in an oil bath at 25 ° C. and 50 ° C. and measuring the resistance values are shown in Table 1.

[0031]

[Table 1]

As can be seen from Table 1, the composite laminated thermistor according to the first embodiment has the external electrodes 4a, 4b
It can be seen that it has the function of the conventional first laminated thermistor having a high resistance value between the external electrodes 4a and 4c, and has the function of the second laminated thermistor of the conventional low resistance value between the external electrodes 4a and 4c.

(Embodiment 2) FIG. 5 is a perspective view of a composite laminated thermistor according to Embodiment 2 of the present invention, and FIG.
7 is a sectional view taken along the line AB of FIG. 5, and FIG.
Denotes an insulator layer, and the same components as those in FIGS. 1 to 3 are denoted by the same reference numerals and description thereof is omitted.

The difference between the second embodiment and the first embodiment is that an insulator layer 5 is provided on the entire boundary surface between the first thermistor layer 1 and the second thermistor layer 2.

The insulator layer 5 does not form a solid solution with the first and second thermistor layers 1 and 2 at the time of firing, and the sintering temperature of the first and second thermistor layers 1 and 2 is substantially the same. It was formed of a ceramic material having substantially the same thermal expansion coefficient as the second thermistor layers 1 and 2.

By providing the insulator layer 5, mutual diffusion between the first thermistor layer 1 and the second thermistor layer 2 during firing is prevented, and between the external electrodes 4a-4b and the external electrodes 4a
-4c can be prevented from varying from desired values.

The composite laminated thermistor is manufactured in the same manner as in the first embodiment.

(Embodiment 3) FIG. 8 is a perspective view of a composite laminated thermistor according to Embodiment 3 of the present invention, and FIG.
AB sectional view of FIG. 10, FIG. 10 is a CD sectional view of FIG.
Reference numeral 6 denotes a shield electrode layer, and the same elements as those in FIGS.

In the composite laminated thermistor of the third embodiment, the first thermistor layer 1 and the second thermistor layer 2 are prevented from interdiffusion at the time of firing similarly to the second embodiment. The shield electrode layer 6 is replaced with the first thermistor layer 1 and the second thermistor layer 2 instead of the insulator layer 5.
Is provided at the boundary surface with

The shield electrode layer 6 is sandwiched between the first thermistor layer 1 and the inner electrode layer 3b closest to the second thermistor layer 2, and between the second thermistor layer 2 and the first thermistor layer 1. Nearest internal electrode layer 3c
One end is connected to the same external electrode 4a as that of the above, and the potential is the same. The other end is not connected to the external electrode 4b and the external electrode 4b
It is formed close to. Also, the side end of the sintered body is formed as close as possible to the side end while ensuring the adhesiveness between the first and second thermistor layers 1 and 2 as much as possible. That is, it is desirable to form the first thermistor layer 1 and the second thermistor layer 2 as large as possible in order to prevent mutual diffusion during firing.

In order to minimize the influence on the characteristics of the composite laminated thermistor, the shield electrode layer 6
Between the internal electrodes 3c and 3d
It is necessary to make the distance between the shield electrode layer 6 and the external electrode 4b as short as possible so that the resistance is negligibly large as compared with the resistance generated between them.

In the third embodiment, the shield electrode layer 6 is connected to the external electrode 4a, but may be disconnected from the external electrodes 4a and 4b as shown in FIG. In this case, the inner electrodes 3b, 3c closest to the shield electrode layer 6
Need not be 4a.

That is, the internal electrodes 3b and 3c are
What is necessary is just to connect to either one of a and 4b. However, at this time, the internal electrode 3d is connected to one of the external electrodes 4a and 4b to which the internal electrode 3c is not connected.

The composite laminated thermistor of this embodiment is also manufactured by the manufacturing method shown in the first embodiment.

[0045]

As described above, according to the present invention, since one composite laminated thermistor has at least two thermistor characteristics, it is possible to contribute to miniaturization of an electronic device using a plurality of thermistors such as a temperature compensation circuit of a crystal oscillator.

[Brief description of the drawings]

FIG. 1 is a perspective view of a composite laminated thermistor according to Embodiment 1 of the present invention.

FIG. 2 is a sectional view taken along a line AB in FIG.

FIG. 3 is a sectional view taken along line CD of FIG. 1;

FIG. 4 is an exploded perspective view of the composite laminated thermistor shown in FIG. 1 before external electrodes are formed.

FIG. 5 is a perspective view of a composite laminated thermistor according to Embodiment 2 of the present invention.

6 is a sectional view taken along a line AB in FIG. 5;

FIG. 7 is a sectional view taken along line CD of FIG. 5;

FIG. 8 is a perspective view of a composite laminated thermistor according to Embodiment 3 of the present invention.

9 is a sectional view taken along a line AB in FIG.

FIG. 10 is a sectional view taken along line CD of FIG. 8;

FIG. 11 is a sectional view of a composite laminated thermistor according to an embodiment of the present invention.

FIG. 12 is a temperature compensation circuit diagram of a general crystal oscillator.

FIG. 13 is a sectional view of a conventional thermistor.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 1st thermistor layer 2 2nd thermistor layer 3a internal electrode layer 3b internal electrode layer 3c internal electrode layer 3d internal electrode layer 4a external electrode 4b external electrode 4c external electrode 5 insulator layer 6 shield electrode layer

 ──────────────────────────────────────────────────続 き Continued on the front page (72) Inventor Tomohisa Okimoto 1006 Kadoma Kadoma, Osaka Prefecture Matsushita Electric Industrial Co., Ltd. 72) Inventor ▲ Taka ▼ Masayuki Hashi 1006 Kadoma, Kazuma, Osaka Pref. Matsushita Electric Industrial Co., Ltd. (72) Inventor Etsuro 1006 Kadoma Kadoma, Kadoma, Osaka Pref. BA10 BB01 BC01 BC02 DA07 DB11 DC10 DD08

Claims (4)

[Claims] 1. A composite laminated thermistor in which at least two laminated thermistors each having an external electrode formed on the surface of a laminate in which a thermistor layer and an internal electrode layer are alternately laminated, wherein the laminated thermistors have different specific resistances. Composite laminated thermistor formed of layers. 2. The composite thermistor according to claim 1, wherein one of the external electrodes of the multilayer thermistor having a high specific resistance is formed on a surface different from a surface on which the external electrode of the multilayer thermistor having a low specific resistance is formed. 3. The composite multilayer thermistor according to claim 1, wherein an insulator layer is provided between the multilayer thermistors. 4. The composite multilayer thermistor according to claim 1, further comprising a shield electrode layer connected to the same external electrode as the internal electrode layer adjacent between the multilayer thermistors.