JPH10144504A - Chip-type thermistor and its manufacture - Google Patents

Abstract

PROBLEM TO BE SOLVED: To enhance the reliability such as mechanical strength, temperature cycle performance, etc., by causing external electrodes to have conductive resin layers touching the end surfaces of a chiplike elementary thermistor body and being connected electrically to surface electrodes, and metal plated layers formed on the conductive resin layers. SOLUTION: A chip-type thermistor 10a has a chiplike elementary thermistor body 1A in the shape of a rectangular parallelepiped made of a ceramic sintered body, external electrodes 3 formed on both end surfaces of the elementary thermistor body 1A, surface electrodes 2 formed on the lateral surfaces of the elementary thermistor body 1A so as to be in continuity with the external electrodes 3, and covering layers 6 of dielectric substances which cover at least these surface electrode formed lateral surfaces out of the four lateral surfaces of this elementary thermistor body 1A. And the external electrodes 3 are composed of conductive resin layers 3D being connected electrically to the internal electrodes 2 at these end surfaces, Ni plated layers 3B formed on the conductive resin layers 3D, and solder plated layers 3C. Consequently, it becomes possible to reduce the dispersion of the resistance values.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a chip type thermistor surface-mounted on a printed circuit board or the like and a method of manufacturing the same, and more particularly to a negative temperature coefficient thermistor whose resistance value decreases with a rise in temperature, and which has a mechanical strength. The present invention relates to a chip-type thermistor having excellent reliability, high accuracy and high reliability, and a method for manufacturing the same.

[0002]

2. Description of the Related Art As a typical product of a chip-type thermistor surface-mounted on a printed circuit board or the like, as shown in FIG. In order to improve solder heat resistance and solder adhesion, a terminal electrode made of a conductive metal layer 3A and a Ni plating layer 3B and a solder plating layer 3C covering the surface thereof are formed. Among them, a chip thermistor 10A having a structure in which at least a side surface on which the surface electrode 2 is formed is covered with a glass layer 4 is provided. Further, as shown in FIG. 6, a chip thermistor 10B having a structure in which an internal electrode 5 is formed in a chip thermistor body 1B is also provided. In this chip-type thermistor 10B, the glass layer 4 has at least a large opposing surface 2 of the four side surfaces of the chip-like thermistor body 1.
It is formed on the side surface (Japanese Patent Application Laid-Open No. 4-127401, Japanese Patent Application No. 7-162006).

[0003] Such a chip thermistor 10A, 1
OB is manufactured as follows.

[0004] Surface electrode, four sides coated with glass layer
Method II for manufacturing a chip-type thermistor manufactured in accordance with the present invention. I- A conductive metal powder such as Ag, Ag / Pd or the like is applied to the front and back main plate surfaces of a thin thermistor body (thermistor wafer) made of a ceramic sintered body shown in FIG. Then, a conductive paste containing glass and glass frit is printed in a predetermined pattern to form a surface electrode 12 as shown in FIG. 8B. I- Thermistor wafer 11 on which surface electrode 12 is formed
A glass layer is formed by printing and applying a glass paste on the main plate surfaces on the front and back sides and baking. The thermistor wafer having the I- glass layer 13 is cut into a rectangular shape in the Y direction in FIG. 8B so as to be orthogonal to the surface electrode pattern to obtain a prismatic thermistor body 14 shown in FIG. 8C. I- Of the four side surfaces extending in the longitudinal direction of the prismatic thermistor body 14, two side surfaces 14a,
As shown in FIG. 8D, a glass layer 13 is also formed on 14b. I-4 The prismatic thermistor element 15 having the glass layer 13 formed on the side surface is cut in a direction orthogonal to the longitudinal direction.
A chip thermistor body 1A having the surface electrodes 2 as shown in FIGS. 8 (e) and 5 and having four side surfaces covered with glass layers 4 and 13 is obtained. I- As shown in FIG. 8 (f), external electrodes 3 are formed on both end surfaces of the chip-shaped thermistor body 1A which are not covered with a glass layer. That is, by applying and baking a conductive paste, the conductive metal layer 3A is baked, and further, a Ni plating layer 3B and a solder plating layer 3C are formed.

[0005] Has a surface electrode, four sides coated with a glass layer
A surface electrode is formed on the thermistor wafer in the same manner as in the method of manufacturing a chip type thermistor II II-I-. II- This thermistor wafer is cut into strips in the same manner as I- to obtain a prismatic thermistor body. II- A glass layer is formed on the four side surfaces extending in the longitudinal direction of the prismatic thermistor body by sputtering or the like, or by applying and baking a glass paste. II-4 A prismatic thermistor body having a glass layer formed on the side surface is cut in the same manner as I-, and external electrodes are formed in the same manner as I-.

[0006] Surface electrode, two sides coated with glass layer
A surface electrode and a glass layer are formed on the thermistor wafer in the same manner as in the method III III-I- of manufacturing the chip-type thermistor . III- This thermistor wafer is made in the same manner as I-, except that the prism-shaped thermistor body is obtained by cutting it in the X direction in FIG. III-The glass layers 13 on the two opposite sides in FIG.
As shown in FIG. 9A, two side surfaces 14a and 14b of the prism-shaped thermistor element body 14 on which the glass layer is not coated are formed as shown in FIG.
An external electrode layer 16 is formed. That is, by applying and baking a conductive paste, the conductive metal layer is baked,
Further, a Ni plating layer and a solder plating layer are formed. III-2 A prismatic thermistor element 17 having a glass layer on two sides and external electrodes formed on the other two sides is shown in FIG.
As shown in the figure, the chip thermistor 18 is cut in a direction perpendicular to the longitudinal direction.

[0007] Internal electrodes, four sides coated with a glass layer
Method IV IV- A ceramic green sheet of thermistor material is prepared by a casting method, and an internal electrode layer is printed at a predetermined position. This internal electrode layer is made of Ag, Ag / P
It can be formed by printing a conductive paste containing a conductive metal powder such as d. IV- A plurality of ceramic green sheets on which the internal electrode layers are printed are laminated and pressed. (Note that a required number of ceramic green sheets on which the internal electrode layers are printed and ceramic green sheets on which the internal electrodes are not printed may be laminated and pressure-bonded.) Then, these are integrally sintered to obtain a laminated plate. IV-Apply and paste a glass paste on the front and back main plate surfaces of the laminate. IV- The laminate having the glass layer obtained is cut into strips to obtain a prismatic thermistor body. IV- Of the four side surfaces extending in the longitudinal direction of the prismatic thermistor body, a glass layer is also formed on two side surfaces not covered with the glass layer. IV-4 A prismatic thermistor element having a glass layer formed on the side surface is cut in a direction perpendicular to the longitudinal direction so that the internal electrode is exposed on the cut surface. To obtain a chip-like thermistor body 1 having four side surfaces covered with a glass layer 4. IV- The conductive metal layer 3A is baked by applying and baking a conductive paste to both end surfaces of the chip-shaped thermistor element body 1 not covered with the glass layer, and further, the Ni plating layer 3B and the solder plating layer 3C are formed. Form.

[0008] Internal electrodes, four sides coated with glass layer
A laminated plate is manufactured in the same manner as in the manufacturing method V V-IV- of the chip thermistor obtained , and the laminated plate is cut into strips to obtain a prismatic thermistor body. V- A glass layer is formed on four side surfaces extending in the longitudinal direction of the prismatic thermistor body by sputtering or the like, or by applying and baking a glass paste. V-4 A prismatic thermistor body having a glass layer formed on the side surface is cut in the same manner as IV-, and external electrodes are formed in the same manner as IV-.

It has an internal electrode and two sides are covered with a glass layer
A laminated plate is obtained in the same manner as in the method of manufacturing a chip thermistor VI VI-IV-, and a glass layer is formed on the front and back main plate surfaces in the same manner as in IV-. VI- The laminate having the glass layer is cut in the same manner as in IV- to obtain a prismatic thermistor body. VI- A conductive metal layer is baked by applying and baking a conductive paste to the two side surfaces of the prismatic thermistor body having the glass layer formed on the two side surfaces not covered with the glass layer,
Further, a Ni plating layer and a solder plating layer are formed. VI-2 A prismatic thermistor body having a glass layer on two side surfaces and external electrodes formed on the other two side surfaces is cut in a direction perpendicular to the longitudinal direction to obtain a chip thermistor.

The chip type thermistor having an internal electrode or a surface electrode manufactured by the above methods I to VI can change the resistance value over a wide range by changing the length of the internal electrode or the surface electrode. In addition, there is an advantage that chip-type thermistors having various resistance values can be manufactured using the same ceramic material.

According to the methods I, II, IV, and V, a prism-shaped thermistor element whose four sides are covered with a glass layer is cut to produce a large number of chip-shaped thermistor elements, and these are formed by a dip method or the like. The method of manufacturing a chip-type thermistor, in which a conductive paste for forming an electrode is simultaneously applied to the cut surfaces of both ends of a large number of chip-shaped thermistor bodies and baked, is extremely excellent in mass productivity. It is excellent in dimensional accuracy. In addition, since the connection surface between the thermistor element and the electrode is set in advance at the time of processing, irrespective of the coating shape of the electrode, variation in the resistance value is extremely small. Moreover, since the entire surface of the element body is covered with the glass layer and the electrode layer, there are various advantages such as excellent environmental resistance.

The chip type thermistor according to the above-mentioned methods III and VI in which only two sides are covered with a glass layer has less environmental resistance than the one in which four sides are covered, but requires less manufacturing steps and lowers cost. It has the advantage that it can be manufactured with.

[0013]

Since the chip-shaped thermistor body of the chip-type thermistor manufactured by the above-mentioned conventional manufacturing method is manufactured by cutting, the apex corners of its four side surfaces and both end surfaces are sharp. It becomes a pyramid shape. For this reason, when mounted on a circuit board, the mechanical stress resulting from bending when the board is cut or the like, or the thermal stress resulting from the difference in the coefficient of thermal expansion of the thermistor body, electrodes, solder, board, etc. during a temperature cycle passes through the external electrodes. The chip concentrates on the apical corner of the chip body, and cracks are likely to occur.

In particular, in the methods III and VI, the prismatic thermistor element body having the glass layer formed on the two side surfaces is cut to form the external electrode layer formed on the remaining two side surfaces, that is, the inorganic material of the glass layer is cut. Since different materials such as a semiconductor ceramic material of a thermistor element and a metal material of an external electrode layer are cut at the same time, stress is easily concentrated on an exposed surface of the element, and particularly, microcracks are easily generated at the apex corners.

Conventionally, efforts have been made to reduce the stress by optimizing the coefficient of thermal expansion of an inorganic layer such as glass with respect to the thermistor body, but it has not been possible to completely solve the problem. In addition, it is also possible to round the corners of the chip-shaped thermistor body by post-processing, but in this method, the processing shape tends to vary, and the chip size becomes smaller due to processing,
There is a problem that the manufacturing cost increases.

An object of the present invention is to solve the above-mentioned conventional problems and to provide a chip type thermistor excellent in reliability such as mechanical strength and temperature cycle performance, and a method of manufacturing the same.

[0017]

According to a first aspect of the present invention, there is provided a chip-type thermistor comprising: a rectangular parallelepiped chip-shaped thermistor body made of a ceramic sintered body; and external electrodes formed on both end surfaces of the chip-shaped thermistor body. A coating layer made of an insulating material covering at least two opposing side faces of the four side faces other than the both end faces, and formed on the side face on which the coating layer is formed so as to be exposed at the external electrode formation end face. A chip-type thermistor comprising: a conductive resin layer in contact with an end surface of the chip-shaped thermistor body and electrically connected to the surface electrode; and a conductive resin layer formed on the conductive resin layer. And a metal plating layer formed thereon.

A chip-type thermistor according to claim 2 is a chip-shaped thermistor element having a rectangular parallelepiped shape made of a ceramic sintered body, external electrodes formed on both end faces of the chip-shaped thermistor element, A coating layer made of an insulating material that covers at least two opposing side surfaces of the four side surfaces, and an internal electrode formed inside the chip-shaped thermistor body so as to be exposed on the external electrode forming end surface. A chip-type thermistor, wherein the external electrode is in contact with an end surface of the chip-shaped thermistor body, and is electrically connected to the internal electrode; and a metal plating layer formed on the conductive resin layer. And characterized in that:

In the chip type thermistor of the present invention, when mounted on a circuit board, mechanical stress caused by bending when the board is cut or the like, or a thermistor element during a temperature cycle,
When thermal stresses due to differences in thermal expansion coefficients of electrodes, solders, substrates, etc., are transmitted to external electrodes, these stresses are relieved by a flexible conductive resin layer serving as a base layer of the external electrodes. For this reason, generation of cracks in the chip-shaped thermistor body due to these stresses is prevented.

In the present invention, it is preferable that the chip-shaped thermistor body has four sides coated with an insulating material.

As the insulating material, an inorganic material or a polymer material can be used.

According to a first aspect of the present invention, there is provided a chip-type thermistor comprising: a step of forming an insulating material layer after forming surface electrodes on front and back main plate surfaces of a thin plate thermistor wafer made of a ceramic sintered body; and forming an insulating material layer. Forming a prismatic thermistor body by cutting the thin plate thermistor thermistor wafer into strips so that the surface electrodes are exposed on the cut surface;
Forming an external electrode layer on two of the four side surfaces extending in the longitudinal direction of the prismatic thermistor body where the insulating material layer is not formed and the body is exposed; and In a method of manufacturing a chip-type thermistor having a step of obtaining a chip-type thermistor by cutting the prism-shaped thermistor element body formed into chips in a direction orthogonal to the longitudinal direction,
In forming the external electrode layer, a conductive resin layer is formed on the two side surfaces where the element body is exposed, and then a metal plating layer is formed on the conductive resin layer by a method of manufacturing a chip thermistor. Can be.

[0023] The chip type thermistor according to claim 1 further comprises:
After forming surface electrodes on the front and back main plate surfaces of the thin thermistor wafer made of ceramic sintered body, forming an insulating material layer, cutting the thin thermistor wafer having the insulating material layer into strips Forming a prismatic thermistor body, and, among four side surfaces extending in the longitudinal direction of the prismatic thermistor body, two insulating material layers formed on the two side surfaces where the insulating body is not formed and the body is exposed Forming a chip-shaped thermistor body by cutting the prismatic thermistor body on which the insulating material layer is formed into chips in a direction perpendicular to the longitudinal direction so that the surface electrode is exposed on the cut surface. And a method of manufacturing a chip-type thermistor having a step of forming external electrodes on both end surfaces of the chip-shaped thermistor element body not covered with an insulating material layer to obtain a chip-type thermistor. In forming the pole layer, a conductive resin layer is formed on both end surfaces where the element body is exposed, and then a chip-type thermistor can be manufactured by a method for manufacturing a chip-type thermistor in which a metal plating layer is formed on the conductive resin layer. .

According to a second aspect of the present invention, there is provided a chip type thermistor comprising a plurality of ceramic green sheets on which an internal electrode layer is formed, a plurality of ceramic green sheets on which an internal electrode layer is formed, and a plurality of ceramic green sheets on which an internal electrode layer is not formed. A step of obtaining a laminated sheet by laminating a plurality of sheets, a step of integrally firing the laminated sheet to obtain a laminated plate, a step of forming an insulating material layer on the front and back main plate surfaces of the laminated plate, and a laminating process of forming the insulating material layer Forming a prismatic thermistor body by cutting the plate into strips such that the internal electrodes are exposed on the cut surface; and, among the four side faces extending in the longitudinal direction of the prismatic thermistor body, Forming an external electrode layer on the two side surfaces on which the material layer is not formed and the element body is exposed; and a step of orthogonally intersecting the prism-shaped thermistor element body on which the external electrode layer is formed with the longitudinal direction. In a method for manufacturing a chip-type thermistor having a step of obtaining a chip-type thermistor by cutting into a chip shape, in forming the external electrode layer, a conductive resin layer is formed on the two side surfaces where the element body is exposed, It can be manufactured by a chip-type thermistor manufacturing method in which a metal plating layer is formed on a conductive resin layer.

According to a second aspect of the present invention, there is provided a chip type thermistor.
A ceramic green sheet on which an internal electrode layer is formed,
Alternatively, a step of obtaining a laminated sheet by laminating a plurality of ceramic green sheets on which an internal electrode layer is formed and a ceramic green sheet not forming an internal electrode layer, and a step of integrally firing the laminated sheet to obtain a laminated plate Forming an insulating material layer on the front and back main plate surfaces of the laminate;
A step of cutting the laminated plate on which the insulating material layer is formed into strips to form a prismatic thermistor body; and forming an insulating material layer among four side surfaces extending in the longitudinal direction of the prismatic thermistor body. Forming an insulating material layer on the two side surfaces on which the element body is not exposed, wherein the prismatic thermistor element body on which the insulating material layer is formed is oriented in a direction perpendicular to the longitudinal direction, and the internal electrode is formed on the cut surface. Step of obtaining a chip-shaped thermistor body by cutting into a chip shape so as to be exposed, and forming a chip-type thermistor by forming external electrodes on both end surfaces of the chip-shaped thermistor body that are not covered with an insulating material layer In the method for manufacturing a chip-type thermistor having a step, in forming the external electrode layer, a conductive resin layer is formed on both end surfaces where the element body is exposed, and then a metal plating layer is formed on the conductive resin layer. Chip thermistor It can be produced by the production method.

[0026]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A chip type thermistor and a method for manufacturing the same according to the present invention will be described below in detail with reference to the drawings.

FIGS. 1 to 3 are sectional views showing an embodiment of the chip type thermistor of the present invention.
Members having the same functions as the members shown in FIGS.

The chip type thermistor 10a shown in FIG.
A rectangular parallelepiped chip-shaped thermistor body 1A made of a ceramic sintered body, external electrodes 3 formed on both end surfaces of the chip-shaped thermistor body 1, and external electrodes 3 on side surfaces of the chip-shaped thermistor body 1A It has a surface electrode 2 formed so as to be conductive, and a coating layer 6 of an insulating material covering at least the side surface on which the surface electrode is formed among four side surfaces of the chip-shaped thermistor body 1A.

The chip type thermistor 10b shown in FIG.
The chip-type thermistor 10a shown in FIG. 1 is different from the formation position of the surface electrode 2, and the other configuration is the same.

The chip type thermistor 10c shown in FIG.
A rectangular parallelepiped chip-shaped thermistor element 1B made of a ceramic sintered body, external electrodes 3 formed on both end surfaces of the chip-shaped thermistor element 1B, and a chip-shaped thermistor exposed on the external electrode-formed end face. The internal electrode 5 formed inside the element body 1B and the chip-shaped thermistor element 1
B has at least two opposing side surfaces having a large area among the four side surfaces.

In these embodiments, the external electrode 3 is
A conductive resin layer 3D which is in contact with the end faces of the chip-shaped thermistor element bodies 1A and 1B and which is electrically connected to the surface electrode 5 or the internal electrode 2 at the end faces; and Ni formed on the conductive resin layer 3D.
It is composed of a plating layer 3B and a solder plating layer 3C.

Such chip type thermistors 10a to 10c
In the production of the chip type thermistor according to the conventional methods I to VI, the conductive resin layer 3
It can be manufactured by forming the external electrode 3 including the D, Ni plating layer 3B and the solder plating layer 3C.

The conductive resin layer is formed by applying a conductive resin paste obtained by forming a conductive metal powder and a thermosetting resin into a paste with an organic solvent, followed by drying and heat curing.

The ratio between the metal powder of the conductive resin paste and the thermosetting resin used here is 70 to 95% by weight of the metal powder in order to secure conductivity and flexibility as an electrode layer. The thermosetting resin is preferably 30 to 5% by weight. When the proportion of the metal powder is less than 70% by weight, the electrical connection between the conductive resin layer 3D and the internal electrode 2 becomes insufficient, and the conductivity of the surface decreases when a plating film is formed by electrolytic plating. This makes it difficult to form a plating film.
If the proportion of the metal powder exceeds 95% by weight, the effect of relieving stress is reduced, which is not preferable.

As the metal powder, a noble metal powder such as Ag or Pd or Ni powder can be used. As the thermosetting resin, epoxy, phenol, xylene, urethane resin and the like can be mentioned.

The conductive resin layer 3 thus formed
For example, the thickness of D is preferably 10 to 200 μm when the final product chip has a length of about 1.6 mm. If the thickness of the conductive resin layer 3D is less than 10 μm,
Insufficient bonding strength and conduction with the chip-shaped thermistor element as a terminal electrode layer, and insufficient stress relaxation effect due to the formation of the conductive resin layer 3D. Happens. In addition,
If the chip size increases, the upper limit may be increased accordingly.

The thickness of the Ni plating layer 3B formed on the conductive resin layer 3D is preferably 1 to 5 μm, and the thickness of the solder plating layer 3C is preferably 2 to 10 μm.

In this embodiment, the Ni plating layer 3B and the solder plating layer 3C are provided as the metal plating layers. Thus, the Ni plating layer 3B and the solder plating layer 3C may be formed. Although more preferable from the viewpoint of solder wettability and heat resistance required for mounting on a substrate, as described above, the conductive resin layer 3D can sufficiently withstand solder erosion without the Ni plating layer. , And the manufacturing cost can be reduced. When the Ni plating layer is omitted, the thickness of the solder plating layer is preferably 3 to 10 μm.

In the present invention, the chip-like thermistor body 1
An insulating inorganic material layer such as a glass layer may be formed as a coating layer 6 made of an insulating material covering the side surfaces of A and 1B, and an insulating polymer material such as an epoxy resin may be formed as in the conventional method. A layer may be formed.

The chip type thermistors 10a-1 of this embodiment
0c, when mounted on a circuit board, the mechanical stress resulting from bending when the board is cut, or the thermal stress resulting from the difference in the coefficient of thermal expansion of the thermistor body, electrodes, solder, board, etc. during a temperature cycle is caused by the external electrode. 3, the conductive resin layer 3D having flexibility as a base layer of the external electrode 3
This alleviates these stresses. For this reason, generation of cracks in the chip-shaped thermistor element bodies 1A and 1B due to these stresses is prevented.

The chip thermistor shown in FIGS. 1 to 3 is an embodiment of the chip thermistor of the present invention,
The chip type thermistor of the present invention is not limited to the one shown in the drawings unless it exceeds the gist.

For example, any of various forms can be adopted for the formation position, the formation range, the number of formation, and the like of the surface electrodes or the internal electrodes.

In particular, when the surface electrode is formed, as shown in FIG. 10, the insulating material between the surface electrode 2 and the conductive resin layer 3D is formed to improve the electrical connection with the conductive resin layer. The coating layer 6 may be a chip-type thermistor 10d formed by removing a part.

[0044]

The present invention will be described more specifically below with reference to examples and comparative examples.

Example 1 A chip type thermistor shown in FIG. 1 was manufactured in the same manner as in the method I except that a conductive resin layer was formed instead of the conductive metal layer.

Commercially available manganese carbonate, nickel carbonate, cobalt carbonate and copper oxide were used as starting materials, each of which was weighed so that the metal atomic ratio became a predetermined ratio, uniformly mixed in a ball mill for 16 hours, and then dehydrated and dried. . Next, this mixture was calcined at 900 ° C. under atmospheric pressure for 2 hours, and the calcined product was again pulverized by a ball mill and dehydrated and dried. An organic binder and the like were added to the pulverized product, granulated to have a particle size of about 60 μm by a spray drier, and compression-molded into a rectangular parallelepiped by a hydraulic press. This molded product is subjected to 120 atmospheric pressure.
Bake at 0 ° C for 4 hours, length 35mm, width 50mm, thickness 1
A 0 mm thermistor sintered block was made. Next, this block was cut into a thin plate with a band saw,
A thermistor wafer having a width of 50 mm, a width of 50 mm and a thickness of 0.80 mm was obtained.

Using a pattern of 0.6 mm in width and 1.1 mm in the width direction on both main plate surfaces of the thermistor wafer, Ag was applied so that electrodes face each other on the main plate surface of the wafer.
After printing the / Pd paste, it was dried, and then the wafer was baked at 820 ° C. for 10 minutes to form a multi-row surface electrode layer having a thickness of about 10 μm.

A glass paste adjusted to a printable viscosity is printed and dried on both main plate surfaces of the thermistor wafer having the surface electrode layer formed in this manner, and is dried at 850 ° C. for about 1 hour.
By baking for 0 minutes and baking, a glass layer having a thickness of about 20 μm was formed. Then, the thermistor wafer on which the glass layer is formed is 0.1 mm by a dicing machine.
In the same manner as above, glass paste was cut on two sides of the obtained prism-shaped thermistor body without coating with a glass layer, so as to be orthogonal to the surface electrode pattern using a blade. By baking, a glass layer having a thickness of 20 μm was formed.

Next, the prism-shaped thermistor element having the four side surfaces coated with the glass layers in this manner was formed into a chip shape having a length of 1.5 mm along a center line of the surface electrode using a 0.1 mm blade by a dicing machine. Cut out.

On both end surfaces of the chip-shaped thermistor element body,
A conductive resin paste containing Ag powder (Ag powder: epoxy resin = 85: 15 (% by weight), and an organic solvent
0% by weight) was applied by a dipping method, dried at 180 ° C. for 10 minutes, and then heated and cured at 220 ° C. for 2 hours to form a conductive resin layer having a thickness of about 50 μm. 2 μm thick N on the surface of the conductive resin layer
An i plating layer was formed, and a solder plating layer having a thickness of about 5 μm was formed thereon.

The chip type thermistor thus manufactured was subjected to a substrate bending resistance test and a temperature cycle test, and the results are shown in Table 1.

The substrate bending resistance test was shown by an average value of 10 samples. The temperature cycle test was performed at -55 ° C and +1
The number of defective products out of 100 tested by a temperature cycle test of 500 cycles in the air at 25 ° C. for 30 minutes each was shown.

Comparative Example 1 A chip-type thermistor was prepared in the same manner as in Example 1, except that a conductive metal layer was formed instead of the conductive resin layer in forming the external electrodes. Were tested in the same manner, and the results are shown in Table 1.

The conductive metal layer was formed to a thickness of about 50 μm by applying an Ag paste (commercially available Ag paste including a glass frit) by dipping, holding at 820 ° C. for 10 minutes and baking.

[0055]

[Table 1]

From the results shown in Table 1, it can be seen that the chip thermistor of the present invention has improved characteristics in terms of substrate bending resistance and temperature cycle test as compared with the conventional chip thermistor.

Example 2 and Comparative Example 2 A chip-type thermistor shown in FIG. 2 was produced in the same manner as in Example 1 except that the formation pattern of the surface electrode was changed (Example 2). A chip thermistor was manufactured in the same manner as in Example 2 except that a conductive metal layer was formed instead of the conductive resin layer in forming the external electrodes (Comparative Example 2). When a test was performed on the mold thermistor in the same manner as in Example 1 and Comparative Example 1, it was confirmed that the chip thermistor of the present invention had improved characteristics as compared with the conventional chip thermistor.

Example 3 The above III except that an epoxy resin layer was formed instead of the glass layer and a conductive resin layer was formed instead of the conductive metal layer.
The chip thermistor shown in FIG. 1 was produced in the same manner as in the above method.

First, a thermistor wafer was manufactured in the same manner as in Example 1, and a surface electrode was formed in the same manner. Thereafter, an epoxy resin was applied to the front and back main plate surfaces of the thermistor wafer on which the surface electrode was formed, and then heated at 180 ° C. By drying for 10 minutes, an epoxy resin layer having a thickness of about 50 μm was formed.

Thereafter, as in Example 1, except that the width is 1.5 m along the center line of the surface electrode in parallel with the surface electrode pattern.
m into strips, surface electrodes are formed on two sides,
A prismatic thermistor body having an epoxy resin coating layer formed on the two side surfaces was obtained.

A conductive resin paste containing Ag powder (Ag powder: epoxy resin = 85: 15 (% by weight),
An organic solvent was added thereto by 10% by weight), applied by dipping, and dried at 180 ° C. for 10 minutes.
The composition was cured by heating at 220 ° C. for 2 hours. The thickness of the formed conductive resin layer is about 50 μm.

Next, the prismatic thermistor body on which the conductive resin layer was formed was immersed in a plating bath, and a Ni plating layer having a thickness of about 2 μm was formed on the surface of the conductive resin layer. A solder plating layer of about 5 μm was formed.

Thereafter, a width of 0.8 is used with a dicing machine.
The chip thermistor was cut into a chip shape of mm.

With respect to the chip type thermistor thus manufactured, a substrate bending resistance test and a temperature cycle test were performed in the same manner as in Example 1 (however, the temperature cycle test condition was-
30 minutes each at 40 ° C and + 85 ° C, in the air, 100 cycles)
And the results are shown in Table 2.

Comparative Example 3 In Example 3, a thickness of about 20 was used instead of the epoxy resin layer.
A chip-type thermistor was prepared in the same manner except that a glass layer of μm was formed and a conductive metal layer was formed instead of the conductive resin layer. The chip-type thermistor was similarly tested, and the results are shown in Table 2. It was shown to.

The glass layer is printed with a glass paste,
It was dried and baked at 850 ° C. for about 10 minutes to form a thickness of 20 μm. The conductive metal layer was formed to a thickness of about 50 μm by applying an Ag paste (commercially available Ag paste including a glass frit) by dipping, holding at 820 ° C. for 10 minutes, and baking.

[0067]

[Table 2]

From the results in Table 2, it can be seen that the chip thermistor of the present invention has improved characteristics in terms of substrate bending resistance and temperature cycle test as compared with the conventional chip thermistor.

Example 4 A chip-type thermistor shown in FIG. 3 was manufactured in the same manner as in the method V except that a conductive resin layer was formed instead of the conductive metal layer.

Commercially available manganese carbonate, cobalt carbonate and iron oxide were used as starting materials, each of which was weighed so that the metal atomic ratio became a predetermined ratio, uniformly mixed in a ball mill for 16 hours, and then dehydrated and dried. Next, this mixture was calcined at 900 ° C. under atmospheric pressure for 2 hours, and the calcined product was again pulverized by a ball mill and dehydrated and dried. An organic solvent, a binder, a dispersant, and the like were added to the obtained raw material powder to prepare a slurry, and a ceramic green sheet having a thickness of 40 μm was prepared by a casting method.

An Ag / Pd paste is printed at a predetermined position on the ceramic green sheet to form an internal electrode layer. The ceramic green sheet on which the internal electrode layer is formed and the ceramic green sheet on which no internal electrode is formed are separated by a predetermined amount. After stacking the sheets, the sheets were pressed by a hydrostatic pressing method, and then dried and baked at a temperature of 1100 ° C. for 5 hours to have a length of 35 mm, a width of 50 mm and a thickness of 0.8.
A laminate of 0 mm was obtained. A glass paste was applied to the front and back main plate surfaces of the laminated plate, dried, and fired at 850 ° C. to form a glass layer having a thickness of 20 μm. Then, a 0.8 mm wide prismatic thermistor body was cut out using a cutting machine,
A glass layer having a thickness of 20 μm was formed on the two side surfaces of the prism-shaped thermistor body which were not covered with the glass layer in the same manner as described above. Then, cut into chips so that the internal electrodes are exposed on the end faces, 1.5 mm long, 0.8 mm wide, and about 0.8 mm thick.
mm chip-shaped body was obtained.

A conductive resin paste containing Ag powder (Ag powder: epoxy resin = 85: 15 (% by weight) and an organic solvent of 10% by weight) were provided on both end surfaces of the obtained element body where the internal electrodes were exposed. % Added) was applied by a dipping method, dried at 180 ° C. for 10 minutes, and then heated and cured at 220 ° C. for 2 hours. The thickness of the formed conductive resin layer is about 50 μm.

Next, a Ni plating layer having a thickness of about 2 μm was formed on the conductive resin layer by electrolytic barrel plating, and a solder plating layer having a thickness of about 5 μm was formed thereon.

The chip type thermistor thus manufactured was subjected to a substrate bending resistance test and a temperature cycle test, and the results are shown in Table 3.

The substrate bending resistance test was shown by an average value of 10 samples. Temperature cycle test is -55 ° C and + 125 ° C
The results are shown by the number of defective products out of 100 samples in a temperature cycle test of 200 cycles in the air for 30 minutes each.

Comparative Example 4 A chip-type thermistor was prepared in the same manner as in Example 4, except that a conductive metal layer was formed instead of the conductive resin layer in forming the external electrodes. Were tested in the same manner, and the results are shown in Table 3.

The conductive metal layer was formed to a thickness of about 50 μm by applying an Ag paste (a commercially available Ag paste containing a glass frit) by dipping and baking.

[0078]

[Table 3]

From the results shown in Table 3, it can be seen that the chip thermistor of the present invention has improved characteristics in terms of substrate bending resistance and temperature cycle test as compared with the conventional chip thermistor.

[0080]

As described above in detail, according to the chip type thermistor and the method of manufacturing the same of the present invention, the reliability such as the mechanical strength and the temperature cycle performance is excellent, the variation of the resistance value is small, and the precision is high. A simple chip thermistor is provided.

[Brief description of the drawings]

FIG. 1 is a sectional view showing one embodiment of a chip type thermistor of the present invention.

FIG. 2 is a sectional view showing another embodiment of the chip type thermistor of the present invention.

FIG. 3 is a sectional view showing another embodiment of the chip thermistor of the present invention.

FIG. 4 is a sectional view showing a conventional chip thermistor.

FIG. 5 is a cross-sectional view showing a chip-shaped thermistor body having a surface electrode.

FIG. 6 is a sectional view showing a conventional chip thermistor.

FIG. 7 is a cross-sectional view showing a chip-shaped thermistor body having internal electrodes.

FIG. 8 is a perspective view illustrating a method of manufacturing a chip thermistor.

FIG. 9 is a perspective view illustrating a method for manufacturing a chip-type thermistor.

FIG. 10 is a sectional view showing another embodiment of the chip type thermistor of the present invention.

[Explanation of symbols]

1A, 1B Chip-shaped thermistor body 2 Surface electrode 3 External electrode 3A Conductive metal layer 3B Ni plating layer 3C Solder plating layer 3D Conductive resin layer 5 Internal electrode 6 Insulating material coating layer 10A, 10B, 10a, 10b, 10c, 10d Chip type thermistor

Claims (9)

[Claims] 1. A rectangular parallelepiped chip-shaped thermistor element made of a ceramic sintered body, external electrodes formed on both end faces of the chip-shaped thermistor element, and four electrodes other than the both end faces.
A coating layer made of an insulating material that covers at least two opposing side surfaces of the side surfaces, and a surface electrode formed on the side surface on which the coating layer is formed so as to be exposed on the external electrode formation end surface. Wherein the external electrode is in contact with an end surface of the chip-shaped thermistor body;
A chip thermistor, comprising: a conductive resin layer electrically connected to the surface electrode; and a metal plating layer formed on the conductive resin layer. 2. A rectangular parallelepiped chip-shaped thermistor element made of a ceramic sintered body, external electrodes formed on both end faces of the chip-shaped thermistor element, and four electrodes other than the both end faces.
It has a coating layer made of an insulating material that covers at least two opposing side surfaces of the side surfaces, and an internal electrode formed inside the chip-shaped thermistor body so as to be exposed on the external electrode forming end surface. In a chip thermistor, the external electrode is in contact with an end surface of the chip thermistor body,
A chip-type thermistor comprising: a conductive resin layer electrically connected to the internal electrode; and a metal plating layer formed on the conductive resin layer. 3. The chip thermistor according to claim 1, wherein the chip-shaped thermistor body has four side surfaces coated with an insulating material. 4. The chip thermistor according to claim 1, wherein the insulating substance is an inorganic substance. 5. The chip thermistor according to claim 1, wherein the insulating substance is a polymer substance. 6. After forming surface electrodes on the front and back main plate surfaces of a thin plate thermistor wafer made of a ceramic sintered body,
Forming an insulating material layer, forming a prismatic thermistor body by cutting the thin thermistor wafer on which the insulating material layer is formed into strips such that the surface electrodes are exposed on the cut surface; Forming an external electrode layer on two of the four side surfaces extending in the longitudinal direction of the prismatic thermistor element body where the insulating body is not formed and the element body is exposed; and A method of manufacturing a chip-type thermistor having a step of obtaining a chip-type thermistor by cutting the formed prism-shaped thermistor body into chips in a direction orthogonal to the longitudinal direction, wherein the body is exposed in forming the external electrode layer Forming a conductive resin layer on the two side surfaces, and then forming a metal plating layer on the conductive resin layer. 7. After forming surface electrodes on the front and back main plate surfaces of a thin thermistor wafer made of a ceramic sintered body,
A step of forming an insulating material layer; a step of cutting the thin plate-shaped thermistor wafer having the insulating material layer formed into strips to form a prismatic thermistor body; and extending in a longitudinal direction of the prismatic thermistor body. Forming an insulating material layer on two of the four side surfaces on which the insulating material layer is not formed and the element body is exposed; and forming the prism-shaped thermistor element body on which the insulating material layer is formed at right angles to the longitudinal direction. In the direction to perform, a step of obtaining a chip-shaped thermistor body by cutting the chip into a chip shape so that the surface electrode is exposed on the cut surface, and, on both end surfaces of the chip-shaped thermistor body which are not covered with the insulating material layer. In a method of manufacturing a chip thermistor having a step of forming an external electrode to obtain a chip thermistor, a step of forming a conductive resin layer on both end surfaces where the element body is exposed, in forming the external electrode layer, Conductive tree Method of manufacturing a chip-type thermistor, and forming a metal plating layer on the layer. 8. A ceramic green sheet having an internal electrode layer formed thereon, or a ceramic green sheet having an internal electrode layer formed thereon and a ceramic green sheet having no internal electrode layer formed by laminating a plurality of ceramic green sheets. Obtaining the laminated sheet, integrally firing the laminated sheet to obtain a laminated plate, forming an insulating material layer on the front and back main plate surfaces of the laminated plate, and cutting the laminated plate having the insulating material layer formed thereon by the internal electrodes. Forming a prismatic thermistor body by cutting it into strips so as to be exposed on the surface; and forming an insulating material layer on the four side surfaces extending in the longitudinal direction of the prismatic thermistor body. Forming an external electrode layer on the two side surfaces where the element body is exposed; and cutting the prism-shaped thermistor element body formed with the external electrode layer into chips in a direction orthogonal to the longitudinal direction. In the method of manufacturing a chip-type thermistor having a step of obtaining a thermistor, a conductive resin layer is formed on the two side surfaces where the element body is exposed in forming the external electrode layer, and then a metal plating is performed on the conductive resin layer. A method for manufacturing a chip-type thermistor, comprising forming a layer. 9. A ceramic green sheet having an internal electrode layer formed thereon or a ceramic green sheet having an internal electrode layer formed thereon and a ceramic green sheet having no internal electrode layer formed by laminating a plurality of ceramic green sheets. Obtaining a laminated sheet by integrally firing the laminated sheet to obtain a laminated plate; forming an insulating material layer on the front and back main plate surfaces of the laminated sheet; cutting the laminated plate on which the insulating material layer is formed into strips; Forming a prism-shaped thermistor body by applying a heat treatment to the surface of the prism-shaped thermistor body. Forming a layer; cutting the prism-shaped thermistor body on which the insulating material layer is formed into chips in a direction perpendicular to the longitudinal direction so that the internal electrodes are exposed on the cut surface; A method for producing a chip thermistor, comprising the steps of: obtaining external body electrodes on both end surfaces of the chip-shaped thermistor element body not covered with an insulating material layer to obtain a chip-type thermistor; A method for manufacturing a chip-type thermistor, comprising: forming a conductive resin layer on both end surfaces where an element body is exposed when forming an electrode layer; and then forming a metal plating layer on the conductive resin layer.