JP2000068109A - Chip-type thermistor and producing method thereof - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a highly reliable chip-type thermistor which is used for surface mount packaging and ensures less variations of a distance between one electrode and the other electrode, and to provide the producing method thereof. SOLUTION: This chip-type thermistor is constituted of a thermistor device 4 having a shape of rectangular parallelopiped, glass layers 5 which coat the surface of the thermistor device 4 excluding the both ends thereof, grounding electrodes 2 formed on the both ends of the thermistor 4, and at least one layer of plated film layers formed on the surface of the grounding electrodes 2. This chip-type thermistor 1 forms an opening part 7 in the glass layers 5 on the surface of the thermistor device to keep an appropriate distance between one electrode and the other electrode. The distance between electrodes formed at the both ends of the thermistor device 4 can be held by the opening part 7. As a result, less variations between electrodes and higher reliability can be ensured.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a chip-type thermistor and a method of manufacturing the same, and more particularly to a chip-type thermistor for surface mounting and having a highly reliable negative characteristic and a method of manufacturing the same.

[0002]

2. Description of the Related Art Conventional chip-type thermistors are disclosed in, for example, Japanese Patent Application Laid-Open No. 3-504551 (hereinafter, Conventional Example 1), Japanese Patent Application Laid-Open No. 3-250603 (hereinafter, Conventional Example 2), and No. 177402 (hereinafter referred to as Conventional Example 3). The chip-type thermistors of Conventional Examples 1 and 2 cover the four sides except for both end faces of a rectangular parallelepiped element body with a glass layer, and then apply conductive electrode portions (for example,
A base electrode) is formed, and a metal plating layer is further provided on the electrode portion. In the chip type thermistor of Conventional Example 3, electrodes are formed on the exposed end faces of the thermistor body on which four inorganic coating layers are formed.

In these conventional examples, silver electrodes formed by applying and baking a silver paste are usually used as base electrodes formed on both end surfaces of the thermistor body.
As a method of applying the silver paste, a stamping method or a screen printing method is used. However, the application by these methods involves not only the application of the silver paste to both end faces of the element body but also the application of an insulating layer (glass layer, inorganic layer, etc.) coated on the element body surface. There is a disadvantage. Furthermore, due to variations in the process conditions such as the viscosity of the silver paste, the ambient temperature and the jig, etc., the silver electrode ends adhere to not only the both end surfaces of the element body but also the insulating layer around the element body, and the ends of the silver electrodes approach each other. May be formed. When a chip-type thermistor is manufactured by such a manufacturing method, even if the electrodes on both end faces are spread as close as possible onto the insulator layer, unless the electrode ends are short-circuited, the resistance is measured. At the quality inspection stage, there is a possibility that the product will be a non-defective product because it shows a normal resistance value.

[0004] When such a chip thermistor in which the ends of both electrodes are close to each other and the gap between the two electrodes is narrow is manufactured and shipped, when such an element is mounted on a printed circuit board, high humidity may result. If the chip type thermistor is used for a long time in a place or in a bad environment, migration, which is a phenomenon of metal movement, occurs between the electrodes of the chip type thermistor, and short-circuit occurs between both electrode ends, so that there is a possibility that the electrode does not function as a temperature sensor.

In recent years, the length of the element body of the chip component, that is, the distance between both end faces of the element, has tended to be shortened. When the chip thermistor is mounted on a device and used in a field, there is a possibility that the chip thermistor may cause a malfunction such as an operation failure. Incidentally, the chip shape is further reduced in size, for example, the size is 1.0
Ultra-small ones having a shape of × 0.5 mm or 0.8 × 0.3 mm have been commercialized. The trend toward miniaturization of chip components is increasing.

[0006]

SUMMARY OF THE INVENTION The present invention has been made in view of the above-mentioned problems, and is intended for surface mounting and has a small variation in distance between electrodes and a highly reliable chip type thermistor, and a method of manufacturing the same. The purpose is to provide. Another object of the present invention is to provide a chip-type thermistor for surface mounting, which has a small variation in distance between electrodes, has high reliability, and can easily adjust a resistance value, and a method for manufacturing the same. It is.

[0007]

In order to achieve the above object, the present invention is directed to a cubic thermistor element and a glass covering the surface of the thermistor element body excluding both end faces. Layer, a base electrode formed on both end surfaces of the thermistor body, and a chip-type thermistor having at least one plating film layer formed on the surface of the base electrode, wherein the glass layer on the surface of the thermistor body, A chip-type thermistor, wherein an opening for keeping the distance between the electrodes is formed. According to this configuration, the distance between the electrodes formed on both end surfaces of the thermistor body is maintained by forming the opening, and the variation in the distance between the electrodes is small, and the reliability is high.

According to a second aspect of the present invention, the opening formed in the glass layer is formed on at least one surface of the thermistor body except for both end faces of the thermistor body. In the invention, the opening formed in the glass layer is formed on at least opposing surfaces of the thermistor body, excluding both end surfaces of the thermistor body. 2. The chip-type thermistor according to claim 1, wherein the openings formed in the thermistor body are formed on four surfaces of the thermistor body. According to these configurations, the opening is formed on one surface, the opposing surface, or the four surfaces of the glass layer formed on the surface of the thermistor element, and the opening is formed on the opposing glass layer of the thermistor element. It is advantageous from the viewpoint of manufacturing that the distance between the electrodes is maintained higher as the number of surfaces on which the openings are formed increases, and the creepage distance between the electrodes is also maintained by maintaining the distance between the electrodes. The reliability is improved. When this opening is used as the bonding surface of the printed circuit board, the temporary bonding of the chip thermistor becomes strong.

According to a fifth aspect of the present invention, in any one of the first to fourth aspects, a resistance adjusting electrode is formed on at least one element body surface except for both end faces of the thermistor element body. It is a chip thermistor as described. According to this configuration, a chip-type thermistor having a predetermined resistance value can be easily formed by trimming the resistance adjusting electrode without changing the composition of the thermistor body.

According to a sixth aspect of the present invention, there is provided the chip thermistor according to any one of the first to fifth aspects, wherein an inorganic insulating film is provided in the opening. The present invention is the chip thermistor, wherein the inorganic insulating film is formed of at least one of a silicon oxide film and an aluminum oxide film. According to this configuration, in a chip type thermistor having a small specific resistance, it is possible to prevent plating adhesion at the time of forming a plating electrode, and when the base electrode or the plating electrode comes into contact with the inorganic insulating film, a change in resistance occurs. In the measurement of the resistance value, defective products can be reliably sorted out.

The invention according to claim 8 is that the base electrode and at least one plating film layer formed on the surface of the base electrode are provided on a glass layer on at least one surface of the thermistor body. The chip-type thermistor according to claim 1, wherein the chip-type thermistor is formed with an opening formed therebetween. According to this configuration, the distance between the electrodes can be reliably maintained, so that the occurrence of migration is suppressed and the reliability can be maintained.

In a ninth aspect of the present invention, the material of the base electrode is mainly composed of silver / palladium alloy or silver,
9. The method according to claim 1, wherein a material of a plating layer plated on the base electrode is nickel or a nickel-based alloy, and a solder plating layer is formed on the plating layer.
The chip-type thermistor according to any one of the above. According to this configuration, the chip thermistor has an opening formed in the glass layer, and the existing electrode forming technology can be applied.

According to a tenth aspect of the present invention, in the method of manufacturing a chip-type thermistor, a body forming step of forming a thermistor body, and a stripe-shaped surface formed on the surface of the thermistor body formed by the body forming step. A glass forming step of forming a glass layer and an entire surface or a striped glass layer on the back surface thereof, and a first step of cutting the element body after the glass forming step into strips in a direction orthogonal to the striped glass layer. A cutting step, a cut-out glass forming step of forming a glass layer in the form of an entire surface or a stripe on the cut-out surface of the element after the first cutting step, and the striped shape of the element formed by the cut-out glass forming step A second cutting step in which the center of the glass layer is cut in the stripe direction to form a chip-shaped body; and both end faces of the chip-shaped body cut out in the second cutting step. It is a manufacturing method of a chip type thermistor which is characterized by comprising an electrode forming step of poles formed. According to this configuration, by forming a stripe-shaped glass layer, by cutting in a direction perpendicular to the stripe-shaped glass layer, an opening serving as a measure for maintaining a distance between electrodes can be easily formed. it can.

According to an eleventh aspect of the present invention, in the method of manufacturing a chip-type thermistor, there is provided an element forming step for forming a thermistor element, and a stripe-shaped glass formed on the surface of the thermistor element formed in the element forming step. A glass forming step of forming a glass layer in the entire surface or a stripe on the layer and the back surface thereof, and a thermistor body after the glass forming step,
A first cutting step of cutting into strips along the center of the individual glass layers in the stripe direction in the stripe direction;
An electrode forming step of forming an electrode on the cut surface of the strip-shaped element body after the cutting step; and after the electrode forming step, the element-formed element is cut out in a direction orthogonal to the stripe-shaped glass layer to form a chip. And a second cutting step of forming a state body. According to this configuration, by forming the stripe-shaped glass layer, an opening can be easily formed, and an electrode can be formed before cutting into individual chips, thereby simplifying a manufacturing process.

According to a twelfth aspect of the present invention, in the method for manufacturing a chip-type thermistor according to the tenth or eleventh aspect, after forming the thermistor body in the body forming step, the surface of the thermistor body is formed. A method for manufacturing a chip-type thermistor, comprising a step of forming a thin film for forming an inorganic insulating film. According to this configuration, when the opening is formed, the structure in which the inorganic insulating film is formed in the opening can be easily formed, and the resistance value changes due to the contact between the inorganic insulating film and the solder plating film layer. In addition, defective products can be reliably eliminated by quality inspection.

According to a thirteenth aspect of the present invention, in the method of manufacturing a chip thermistor according to any one of the tenth to twelfth aspects, a resistance adjusting electrode is formed on a surface of the thermistor body. It is a manufacturing method of a chip type thermistor. According to this configuration, the resistance adjustment electrode is provided on the thermistor element, and the resistance value of the chip-type thermistor can be easily adjusted. Therefore, it is not necessary to set the resistance value by adjusting the composition of the element body itself. , Making it easier to manufacture.

[0017]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of a chip type thermistor and a method of manufacturing the same according to the present invention will be described with reference to FIG.
This will be described with reference to FIGS.

Embodiment 1 Embodiment 1 of the present invention will be described with reference to FIGS. FIG. 1 (a)
1 is a perspective view showing an embodiment of a chip type thermistor, and FIG.
(B) is a sectional view as seen from the directions of the arrows X and Y. 2A to 2F are perspective views for explaining a manufacturing method thereof. In FIG. 1, a chip thermistor 1
A base electrode 2 formed on both end surfaces of the thermistor body 4 having a rectangular parallelepiped shape, a plating electrode layer 3 such as a nickel plating layer formed on the surface of the base electrode 2, and a solder plating layer 8 on the plating electrode layer 3. And a glass layer 5 is provided on the surface of the thermistor body 4 except for both end faces of the thermistor body 4, and an opening 7 is formed in the glass layer 5 on at least one surface of the thermistor body 4.

With reference to FIGS. 2A to 2F, a method of manufacturing the chip type thermistor will be described. First, manganese oxide (Mn) was used to form the thermistor body 4.
O ₂ ), cobalt oxide (CoO), nickel oxide (Ni
O) The oxide powder was weighed at a metal atomic ratio of 1: 1: 1 and mixed in a ball mill for 10 hours.
Dehydrate and dry. The mixture is heated at 900-1000 ° C for about 2
After calcining for an hour and pulverizing again by a ball mill, 10 wt% of polyvinyl butyral was used as a binder and ethanol 1 was used.
A kneaded material was prepared by adding 5% by weight and 1% of a lubricant. Next, a green sheet having a thickness of about 0.9 mm was prepared by extrusion molding the kneaded material, and the green sheet was 60 × 60 m
m size. This sheet is 1100-12
Firing was performed at 50 ° C. for about 1 hour to obtain a thermistor body 4 as shown in FIG.

A glass paste containing silicon oxide (SiO ₂ ) and boron oxide (B ₂ O ₃ ) as main components is formed on the surface of the thermistor body 4 to form a glass layer 5 as shown in FIG. 1.0mm width, 0.5m pitch
m, and a glass paste is printed on the entire back surface of the thermistor element 4 and baked at 750 to 950 ° C. to form the glass layer 5 ′. Glass layers 5, 5 'each having a thickness of about 15 .mu.m are formed on both sides. Next, as shown in FIG. 2 (c), this is cut out in a direction perpendicular to the glass layer formed in a stripe shape so as to be a strip having a width of 0.7 mm. Then, as shown in FIG. 2D, a glass layer 6 having a thickness of about 15 μm was formed on the cut surface by the same method as described above.
6 ′ (the same material as the glass layer 5) is formed.

FIG. 2 (e) shows the central portion of the strip-shaped glass layer 5 of the strip-shaped thermistor body 4 on which the glass layers 5, 5 ', 6, 6' are formed. Cut in the stripe direction as shown
Is formed. As shown in FIG. 1B, a silver paste is applied to the cut surface and a part of the glass layers 5, 5 ', 6, 6' around the cut surface and baked at about 750.degree. Form. Next, a nickel plating layer 3 having a thickness of about 2 μm was formed on the base electrode 2 by electrolytic plating.
Further, a solder plating layer 8 of Sn / Pb having a thickness of about 3 μm is formed thereon. Then, the chip type thermistor 1 shown in FIG. 2F is obtained.

As is clear from FIGS. 1 and 2, the chip-type thermistor of this embodiment has a structure in which an opening 7 is formed at least in a part of the surface of the thermistor body 4 excluding both end faces. Therefore, when a part of the base electrode 2 adheres to the thermistor body portion exposed from the opening 7 beyond the glass layer 5, the electrode interval between the base electrodes 2 is substantially reduced. Since the resistance value of the thermistor 1 shows an extremely low value, it can be removed as a characteristic failure in the resistance value selection step.

As described above, the present embodiment relates to a chip-type thermistor having a structure in which an opening 7 is formed in a part of a glass layer formed on the surface of the chip-shaped thermistor body 4 except for both end faces. Stated. In the chip-type thermistor having this structure, an opening 7 is formed on only one surface (glass layer 5) of the thermistor body 4 so that the body is exposed. Since the glass layer 5 'is formed on the entire surface and the opening 7 is formed only on one elementary surface, even if the base electrode on the other elementary surface is as close as possible, it may be selected as a good product. . However, as compared with the conventional example, since the creeping distance of the distance between the electrodes on one surface of the thermistor body is maintained, the effect of reducing the probability of occurrence of migration can be obtained.

Further, the chip type thermistor of the present embodiment has good temporary bonding with the printed circuit board by adhering an adhesive to the opening, and prevents the chip type thermistor from standing up or falling off in flow soldering. It has a secondary effect that can be eliminated. However, in the present embodiment, there is still room for improvement in terms of reliability such as occurrence of migration.

(Embodiment 2) FIGS. 3 and 4 show Embodiment 2 of the present invention, in which the above-described embodiment is further improved. FIG. 3A is a perspective view of the present embodiment, and FIG.
Is a sectional view as seen from the directions of the arrows X and Y. FIG.
FIG. 3 is a perspective view illustrating an outline of a manufacturing process of the present embodiment.
In the present embodiment, as shown in FIGS. 3A and 3B, an opening 7 'is provided on the back surface side corresponding to the opening 7 formed in the chip type thermistor of the embodiment of FIG. This is a chip-type thermistor having the same structure as that of the first embodiment, and other configurations are the same as those of the first embodiment.

Next, an outline of the manufacturing process of this embodiment will be described with reference to FIG. First, the method of manufacturing the thermistor body 4 shown in FIG. As shown in FIG. 4 (b), a glass paste containing SiO ₂ and B ₂ O ₃ as main components is applied to both surfaces of the sintered thermistor element 4 and the width is adjusted so that the front and back correspond to each other as shown in FIG. The glass layers are printed in a stripe shape of 1.0 mm and a pitch of 0.5 mm and fired at 750 to 950 ° C. to form glass layers 5 and 5 ′ of about 15 μm. This is cut out into a strip having a width of 0.7 mm as shown in FIG. 4C, and a glass layer 6 of about 10 μm is formed on the cut surface by the same method as described above.
6 'is formed (FIG. 4D). The central portion of the glass layer 5 formed in a strip shape of the strip-shaped thermistor body on which the glass layers 5, 5 ', 6, 6' are formed is cut as shown in FIG. A chip-like element having a length of 1.5 mm was formed. Next, the process proceeds to an electrode forming step, and FIG.
As shown in (b), a silver paste is applied to the cut surface and a part of the glass layers 5, 5 ', 6, 6' around the cut surface.
The base electrode 2 is formed by baking at 00 to 800 ° C. Further, a thickness of about 2 μm is formed on the underlying electrode 2 by electrolytic plating.
a nickel plating layer 3 having a thickness of about 3 μm.
A solder plating layer 8 of m / Sn / Pb is formed. Then, a chip type thermistor 1 as shown in FIG.

In the chip type thermistor 1 of this embodiment, a part of the base electrode 2 extends beyond the glass layers 5 and 5 ', and the openings 7 and
When it adheres to the portion 7 '(thermistor body), the electrode interval between the base electrodes 2 is substantially reduced.
The resistance value of the chip type thermistor 1 shows an extremely low value and can be removed as a characteristic failure in the resistance value selection step. As described above, the openings 7, 7 'are intervals at which the resistance value changes when the silver paste is adhered thereto and the base electrode 2 is formed. That is, a substantially allowable electrode interval is formed by the opening. Alternatively, the creepage distance between the electrodes is maintained by the opening.

(Embodiment 3) FIGS. 5 (a) and 5 (b) show Embodiment 3 of the present invention, which is a further improved embodiment of the above embodiment. FIG. 5A is a perspective view of the present embodiment, and FIG. 5B is a cross-sectional view as seen from the directions of the arrows X and Y. In the chip-type thermistor of the present embodiment, as shown in FIG. 5, an opening 7 exposing the thermistor body 4 is formed in the glass layer 5 formed on the surface of the thermistor body 4 except for both end faces. Structure. That is, the glass layers 5, 5 ', 6, 6' of the chip-type thermistor of the present embodiment are formed on the periphery except the both end surfaces of the thermistor body, and have a structure in which openings are formed on all four surfaces. is there.

Therefore, in this embodiment, of the four surfaces,
When a part of the base electrode 2 on one surface is attached to the surface of the thermistor body in the portion of the opening 7 beyond the glass layer 5, the electrode interval between the base electrodes 2 is substantially reduced. Since the resistance value of the chip thermistor 1 shows an extremely low value, it can be removed as a characteristic failure in the resistance value selection step. The chip-type thermistor according to the present embodiment enables more strict resistance value selection than in the case of the second embodiment. Even if the chip-type thermistor of this embodiment is mounted on a printed circuit board and used under a severe environment, the occurrence of migration can be suppressed. In this embodiment,
When the strip-shaped thermistor body 4 is cut out, the cut-out surface of the strip-shaped thermistor body 4 may be individually printed with a striped glass paste. It is preferable to form the glass paste by printing and baking a striped glass paste.

As described above, in the first to third embodiments, the element body surfaces (four surfaces) excluding both end faces of the chip-shaped thermistor element body
The chip-type thermistor having a structure in which an opening is formed in at least a part of the glass layer formed in the above is described. As such a chip type thermistor, those having various resistance values are used depending on applications. Therefore, usually, products having various resistance values must be prepared in order to cope with various uses. Therefore, it is necessary to prepare materials having various specific resistances as raw materials of the thermistor body, and to select and produce raw materials having an appropriate specific resistance as required. On the other hand, if the thermistor element 4 is made of a material having a relatively high specific resistance, the nickel plating layer 3
In the case of forming, there were no problems such as erosion of the element body during plating, adhesion of plating to the element, and erosion of the interface between the electrode and the element. This is because only the electrode surface can be plated by adjusting the current during plating. Therefore, as in the first, second, and third embodiments, an opening is formed on at least one of the remaining four surfaces excluding both end surfaces of the thermistor body 4, and the thermistor body 4 is formed from the opening through the opening. Even with the exposed structure, there was no problem such as the opening being plated when the plating electrode was formed after the formation of the base electrode.

However, in the first, second, and third embodiments, in the case of a chip-type thermistor using a material having a low specific resistance as the material of the thermistor body 4, in the plating step of forming a plating electrode on the base electrode, The opening formed in the layer is plated, or the exposed surface of the thermistor body is eroded during the formation of the plated layer, which causes a problem that the variation in resistance value is increased and the reliability such as moisture resistance is reduced. Occurred. Therefore, in order to solve these problems, an embodiment in which the above-described problems are improved,
This will be described below.

(Embodiment 4) Embodiment 4 of the present invention will be described with reference to FIG. FIG. 6A is a perspective view of the present embodiment, FIG. 6B is a cross-sectional view as viewed from the direction of the arrows X and Y, and FIG. 6C is an arrow X and Y of the modified embodiment. It is sectional drawing seen from the direction. FIG. 6 (a),
In (b), the chip-type thermistor 1a has an inorganic insulating film 9 formed on a surface of an opening 7 formed in a glass layer 5 of a thermistor body 4 having a rectangular parallelepiped shape. The surfaces of the thermistor body 4 other than both end faces of the thermistor body 4 are covered with glass layers 5, 5 ', 6, 6'. FIG. 6 (c)
Has a structure in which an opening 7 ′ is provided on the back surface side corresponding to the opening 7, and inorganic insulating films 9 and 9 ′ are formed. In any of the embodiments, both end surfaces of the thermistor body 4 are provided with a base electrode 2, a nickel plating layer 3 and a solder plating layer 8 formed on the surface of the base electrode 2, and the openings 7, 7 'are made of inorganic insulating material. The membrane 9 is exposed. An opening 7 is formed in at least one surface of the glass layer 5 of the thermistor body 4. The inorganic insulating film 9 or 9 ′ may be formed in the opening 7. After the opening 7 or 7 ′ is formed, the opening 7
Alternatively, an inorganic insulating film may be formed at 7 'by a known method.

Next, a method for manufacturing the chip-type thermistor of this embodiment will be described. First, in order to make a thermistor body, manganese oxide (MnO ₂ ) and cobalt oxide (C
oO) and an oxide powder of copper oxide (CuO) were weighed at a metal atomic ratio of 2.5: 2.5: 1, mixed in a ball mill for 10 hours, and then dehydrated and dried. The kneaded material was calcined at 900 to 1000 ° C. for about 2 hours, and was again pulverized by a ball mill. Then, 10 wt% of polyvinyl butyral and 15 wt% of ethanol were used as a binder, and a lubricant 1 was used.
% Was added to prepare a kneaded material. Next, a green sheet having a thickness of about 0.9 mm was prepared from the kneaded material by extrusion and punched out into a size of 60 × 60 mm. This sheet was fired at 1100 to 1250 ° C. for about 1 hour, and FIG.
A thermistor body 4 similar to (a) was obtained.

The entire surface of the thermistor body 4 is sputtered using a sputtering device to form 0.5 to 1.0 μm silicon oxide (SiO ₂ ) or aluminum oxide (A1).
An inorganic insulating film 9 of ₂ O ₃ ) is formed.

Next, a thermist on which the inorganic insulating film 9 is formed
SiO on the surface of the element body 4_Two, B_Two0 _ThreeThe main component of
The lath paste was applied to a thickness of about 1.0 mm, as in FIG.
Printed in stripes with a pitch of 0.5 mm.
-A glass paste is printed on the entire back of the Mister 4
Printed and fired at 750-950 ° C, about 15μm glass
The layers 5, 5 'are formed. This is made the same width as in FIG.
Cut out into 0.7mm strips, and apply the same
A glass layer 6, 6 'of about 15 .mu.m is formed in a similar manner.
(Same as FIG. 2D). And the glass layer is formed
Strip-shaped thermistor body
The central part of the glass layer 5 was cut to a length of 1.5 mm.
A chip-like body is formed.

Subsequently, the process proceeds to an electrode forming step, in which a silver paste is applied to the cut surface and a part of the glass layers 5, 5 ', 6, 6' around the cut surface and baked at about 750.degree. Form. A nickel plating layer 3 having a thickness of about 2 μm is formed on the base electrode 2 by electrolytic plating, and a solder plating layer 8 of Sn / Pb having a thickness of about 3 μm is further formed thereon. Then, a chip thermistor la shown in FIGS. 6A and 6B is formed.

FIG. 6 (c) shows another modified embodiment, in which the inorganic insulating films 9, 9 'are formed on the front and back surfaces of the thermistor body 4 in the form of a sheet by using a sputtering apparatus. FIG. 4 is a cross-sectional structural diagram of a chip type thermistor lb made from the above. The thermistor body 4 is made of an inorganic insulating film 9, 9 '.
And the glass layers 5 formed on the front and back surfaces excluding both end surfaces of the thermistor body 4
6 (a) and 6 (b), except that openings 7 and 7 'are formed in a part of 5', so that the description of the manufacturing method and structure is omitted.

In the present embodiment, as shown in FIG. 6, the inorganic insulating film 9 is provided in the opening 7, and the inorganic insulating film 9 is plated when the plating electrode is formed on the base electrode 2. There is no. Further, when the base electrode 2 adheres to the opening 7 beyond the glass layer 5 when forming the base electrode, the inorganic binder in the conductive paste forming the base electrode 2 reacts with the inorganic insulating film 9 at the time of baking. , That portion of the inorganic insulating film 9
Disappears, and the thermistor body 4 and the underlying electrode 2 come into electrical contact. As a result, a change occurs in the resistance value between the electrodes of the chip thermistor, which appears as a variation in the resistance value. Therefore, it is expected that the element having a large change in the resistance value has the base electrode protruding from the glass layer. Therefore, by eliminating such a chip type thermistor by the resistance value selection, the reliability is improved. It is possible to produce a high chip thermistor. The inorganic insulating film 9 below the glass layer 5 disappears in the subsequent baking process and remains only in the opening 7.

Of course, since the inorganic insulating film 9 'is formed also in the opening 7', the inorganic insulating film 9 'in the opening is not plated when the plating electrode is formed on the base electrode 2. . Even if the base electrode 2 adheres to the inside of the opening 7 'beyond the glass layer 5' at the time of formation of the base electrode, the inorganic binder in the conductive paste constituting the base electrode 2 is burned at the inorganic insulating film 9 '. , The inorganic insulating film 9 'in that portion disappears, and the thermistor body 4 and the underlying electrode come into electrical contact.

(Embodiment 5) A chip type thermistor of the present invention and a method of manufacturing the same will be described with reference to FIGS. FIG. 7A is a perspective view of the present embodiment,
FIG. 7B is a cross-sectional view as seen from the directions of the arrows X and Y. FIGS. 8A to 8D are perspective views showing the outline of the manufacturing process of the chip-type thermistor 1c of the present embodiment. In this embodiment, a chip-type thermistor 1 in which an inorganic insulating film is formed on a corresponding surface of
c. The chip-type thermistor of FIG. 7 is an element in which the cut surface of the thermistor body 4 is exposed, and its electrode structure is the same as the structure described in the above embodiment.

Next, a manufacturing method of the present embodiment will be described with reference to FIG. 8A, as shown in FIG. 2A, a sheet-shaped thermistor element 4 is formed, and inorganic insulating films 9 and 9 'are formed on the front and back surfaces of the thermistor element 4 using a sputtering apparatus. Formed. As shown in FIG. 8B, on the inorganic insulating films 9 and 9 ', glass layers 5 and 5' are formed in a stripe shape by printing and firing. After forming the glass layers 5, 5 ', the stripe-shaped glass layers 5, 5' are formed.
The center part of 5 ′ is cut in the stripe direction to have a width of 1.5
Thermistor body 4 in the form of a strip or stick having a thickness of mm is formed. Then, an electrode is formed on the cut surface as shown in FIG. 8C. This electrode formation is shown in FIG.
As shown in (b), a silver paste is applied and baked to form a base electrode 2, and an electrode composed of a nickel plating layer 3 and a solder plating layer 8 is formed on the base electrode 2. In these electrode forming steps, the same materials are used as in the above embodiment, and the electrodes are formed by the same method. Finally, the chip is cut into a chip having a width of 0.7 mm to obtain a chip thermistor 1c as shown in FIG. 8D. In the present embodiment, the example in which the inorganic insulating film 9 is formed is shown. However, when the thermistor element 4 has a high specific resistance, the inorganic insulating films 9 and 9 ′ are not necessarily required.
It is not necessary to provide. The inorganic insulating film 9 is formed as shown in FIG.
After the step (b), an inorganic insulating film may be formed in a portion where an opening is to be formed by a method such as sputtering.

In this embodiment, the thermistor body 4
Is manufactured by the method described in the above embodiment, and a glass layer and an inorganic insulating film formed on the surface thereof are also formed by the method described in the above embodiment. As another method for forming the inorganic insulating film, a known method other than the above, such as a PVD method, a CVD method, or a vacuum deposition method, can be used. Of course, the same applies to the following embodiments. Further, in the manufacturing method of the present embodiment, since the electrodes are formed on the cut-out surface of the strip-shaped or stick-shaped thermistor element 4, the electrodes are formed on the chip-shaped element, so that the productivity is good. In the present embodiment, the cut-out surface of the strip-shaped or stick-shaped thermistor body 4 on which the electrodes are formed has the thermistor body exposed.

(Embodiment 6) A chip type thermistor of the present invention and a manufacturing method thereof will be described with reference to FIG. FIG. 9A is a perspective view of the present embodiment, and FIG.
(B) is a sectional view as seen from the arrows X and Y. FIG.
(C) is sectional drawing which shows the modification embodiment. FIG.
Chip type thermistor 1d of the embodiment of (a), (b)
Is an embodiment in which the resistance value of the thermistor body 4 can be adjusted to a desired resistance value by a resistance adjusting electrode without adjusting the resistance value. The chip type thermistor 1d of the present embodiment is different from the embodiment of FIG.
The structure is the same as that of the embodiment shown in FIG. In this embodiment, after the resistance adjusting electrode 10 is formed on the surface of the thermistor body 4, it can be formed in the same manufacturing process as that of FIG. Electrode for resistance adjustment 1
With 0, the resistance value can be adjusted without adjusting the resistance value of the thermistor body. Of course, Figures 1,3
The electrode 10 for resistance adjustment is also used for the chip type thermistors 5 and 7.
Obviously, the same effect can be obtained by forming 10 '.

Normally, the chip type thermistor has both end surfaces at which the element and the electrode are in contact with each other, and the resistance value is determined by the contact area of this portion. As a method of adjusting the resistance value of the thermistor element, the composition of the material constituting the thermistor element must be changed in order to adjust the specific resistance. Therefore, in order to prepare products having various resistance values, it is necessary to prepare elements having other material compositions, and it has been difficult to manufacture them. But,
In the present embodiment, in order to facilitate the adjustment of the resistance value, a resistance adjustment electrode (hereinafter, adjustment electrode) 10 for adjusting the resistance value between the electrodes is provided on the surface of the element body. By trimming the electrode 10 for use, a chip thermistor having a predetermined resistance value can be easily manufactured.

In this embodiment, when the length of the adjustment electrode 10 is shorter than the length of the glass layer 5 forming the opening 7, the electrode end of the base electrode 2 is connected to the opening 7 in the same manner as in the previous embodiment. In this case, the contact with the inorganic insulating film 9 greatly changes the resistance value. Therefore, a product having such a large change in resistance value can be selected as a defective product.
FIG. 9B shows a case where the length of the glass layer 5 and the length of the adjustment electrode 10 are substantially the same. Also in this case, the base electrode 2 comes into contact with the inorganic insulating film 9 in the opening 7 to greatly change the resistance value, and can be selected as a defective product.

On the other hand, the length of the adjustment electrode 10 is
When the length of the glass layer 5 is longer than the length of the glass layer 5, no large change in the resistance value is observed even if the electrode end of the base electrode 2 spans the opening 7. That is, even if the inorganic insulating film 9 in contact with the adjustment electrode 10 and the base electrode 2 react, the thermistor element 4
Since no electrical contact is made between the electrode and the underlying electrode, no change in the resistance value is observed. However, with such a structure, by trimming the portion of the adjustment electrode 10 exposed in the opening 7 using a laser trimming device, more precise resistance adjustment becomes possible, and the final resistance is adjusted. The yield of value can be further improved.

In this embodiment, the adjustment electrodes are formed on two surfaces. However, if the adjustment of the resistance value is slight, they may be formed on only one surface. FIG.
(C) is a modified embodiment of Embodiment 6 of the chip thermistor, but it is clear that the chip thermistors of FIGS. 1, 3, 5, and 7 may be provided with adjusting electrodes. In the present embodiment, the thermistor body is not limited to the above embodiment, and in addition to the manganese oxide, cobalt oxide, and nickel oxide of the above embodiment, a material obtained by adding aluminum oxide is mixed at an arbitrary ratio. It may be something. Further, the element body having a predetermined specific resistance may be formed by using other materials.

[0048]

As described above, according to the present invention,
An opening is formed in the glass layer formed on the surface except for both end surfaces of the thermistor body, and a base electrode layer is formed on both end surfaces and a plating electrode layer is formed on the base electrode layer. In the case of contacting a part of the opening, there is an effect that it can be selectively removed as a defective product having an abnormal resistance value when the resistance value of the finished product is selected. Therefore, the chip-type thermistor selected as a non-defective product maintains the electrode interval at least between the glass layers, that is, the opening or more, and can provide a highly reliable chip-type thermistor. Therefore, in the use environment of the chip type thermistor, there is an effect that the reliability against migration and the like is remarkably improved as compared with the conventional products.

The reliability of the chip type thermistor changes by adjusting the width of the opening (the direction between the electrodes or the length direction). Therefore, if the chip type thermistor is miniaturized, the opening of the opening is correspondingly reduced. If the width is designed to be large, the reliability against migration and the like is significantly improved as compared with the conventional products.

Further, according to the present invention, since the opening is formed, the resistance value can be easily adjusted by trimming the element surface or the adjustment electrode using a laser trimming device. This has the effect that adjustment of specific resistance and the like is not required.

[Brief description of the drawings]

FIG. 1A is a perspective view showing a chip type thermistor and a method for manufacturing the same according to a first embodiment of the present invention, and FIG.

FIGS. 2A to 2F are perspective views showing Embodiment 1 of a method for manufacturing a chip thermistor of the present invention.

FIG. 3A is a perspective view showing a chip-type thermistor and a method for manufacturing the same according to a second embodiment of the present invention, and FIG.

FIGS. 4A to 4F are perspective views showing Embodiment 2 of the method for manufacturing a chip thermistor of the present invention.

FIG. 5A is a perspective view showing a chip-type thermistor and a method for manufacturing the same according to a third embodiment of the present invention, and FIG.

6A is a perspective view showing a chip-type thermistor and a method for manufacturing the same according to a fourth embodiment of the present invention, FIG. 6B is a cross-sectional view of the thermistor seen from the direction of the arrow XY, and FIG. It is sectional drawing which shows the modification of FIG.

FIG. 7A is a perspective view showing a chip-type thermistor and a method for manufacturing the same according to a fifth embodiment of the present invention, and FIG.

8 (a) to 8 (d) are perspective views showing Embodiment 5 of the method for manufacturing a chip thermistor of the present invention.

9A is a perspective view showing a chip-type thermistor and a method for manufacturing the same according to a sixth embodiment of the present invention, FIG. 9B is a cross-sectional view of the chip-type thermistor seen in the direction of the arrow XY, and FIG. It is sectional drawing which shows the modification of Embodiment 6.

[Explanation of symbols]

 1, 1a-1d Chip type thermistor 2 Base electrode 3 Plating electrode layer (for example, nickel plating layer) 4 Thermistor element 5, 5 'Glass layer 6, 6' Glass layer 7, 7 'Opening 8 Solder plating layer 9, 9 'inorganic insulating film 10, 10' electrode for resistance adjustment

Claims (13)

[Claims] 1. A thermistor element having a rectangular parallelepiped shape, and a glass layer covering a surface excluding both end faces of the thermistor element,
In a chip type thermistor having a base electrode formed on both end surfaces of the thermistor body and at least one plating layer formed on the surface of the base electrode, the glass layer on the thermistor body surface has a distance between the electrodes. The chip type thermistor characterized in that an opening for keeping the temperature was formed. 2. The thermistor body according to claim 1, wherein the opening formed in the glass layer is formed on at least one surface of the thermistor body except for both end faces of the thermistor body. Chip thermistor. 3. The method according to claim 1, wherein the openings formed in the glass layer are formed on at least opposing surfaces of the thermistor body, excluding both end surfaces of the thermistor body. The described chip-type thermistor. 4. An apparatus according to claim 1, wherein said openings formed in said glass layer are formed on four surfaces of said thermistor body, excluding both end faces of said thermistor body.
The chip-type thermistor according to 1. 5. The chip-type thermistor according to claim 1, wherein a resistance adjusting electrode is formed on at least one element body surface except for both end faces of said thermistor element body. 6. The chip thermistor according to claim 1, wherein an inorganic insulating film is provided in the opening. 7. The chip thermistor according to claim 6, wherein said inorganic insulating film is formed of at least one of a silicon oxide film and an aluminum oxide film. 8. The base electrode and at least one plating film layer formed on a surface of the base electrode are formed with an opening provided in a glass layer on at least one surface of the thermistor body. The chip thermistor according to claim 1, wherein: 9. The material of said base electrode is mainly composed of silver / palladium alloy or silver, and the material of a plating layer plated on said base electrode is nickel or a nickel-based alloy. 9. The chip type thermistor according to claim 1, wherein a solder plating layer is formed on the chip type thermistor. 10. A method for manufacturing a chip-type thermistor, comprising: a body forming step of forming a thermistor body; a stripe-shaped glass layer on the surface of the thermistor body formed by the body forming step; A glass forming step of forming a stripe-shaped glass layer; a first cutting step of cutting the element body after the glass formation step into a strip in a direction orthogonal to the stripe-shaped glass layer; A cutting surface glass forming step of forming a glass layer on the element body cutting surface after the cutting step, and cutting the center of the striped glass layer of the element formed by the cutting surface glass forming step in a stripe direction to form a chip. A second cutting step of forming the elementary body, and an electrode forming step of forming electrodes on both end surfaces of the chip-shaped elementary body cut out in the second cutting step. A method for manufacturing a chip thermistor. 11. A method for manufacturing a chip-type thermistor, comprising: a body forming step of forming a thermistor body; a stripe-shaped glass layer on the surface of the thermistor body formed by the body forming step; Or a glass forming step of forming a stripe-shaped glass layer; and a first cutting step of cutting the thermistor body after the glass forming step into strips in the stripe direction along the centers of the individual stripe-shaped glass layers. An electrode forming step of forming an electrode on a cut surface of the strip-shaped element body after the first cutting step; and, after the electrode forming step, the strip-shaped element body on which the electrode is formed is removed from the strip-shaped glass layer. A second cutting step of cutting out in a direction orthogonal to the above to form a chip-shaped element body. 12. The method for manufacturing a chip-type thermistor according to claim 10, wherein an inorganic insulating film is formed on at least one surface of the thermistor body after forming the thermistor body in the body forming step. A method for manufacturing a chip-type thermistor, comprising: 13. The method for manufacturing a chip thermistor according to claim 10, wherein a resistance adjusting electrode is formed on a surface of said thermistor body.