JP2001338803A - Resettable fuse element and its manufacturing method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a resettable fuse element which has a distinct conductive path and high resistance in an arbitrary section in the case of the minifestation of PTCR characteristics, can he used in safety and has low resistance and stable product characteristics at a lower cost by a stable manufacturing method. SOLUTION: The resettable fuse element which is composed of conductors, through which a current in the case of a stationary case flows, and matrix bodies 3 having resistivity higher than the conductors and has PTCR characteristics and in which the conductors are constituted of electrode sections 4 and PTC sections 1, the electrode sections 4 are formed of a pairs of opposed layers, the PTC sections 1 are formed of pairs of layers opposed in the same manner as the electrode sections 4 on the insides of a pair of the electrode sections 4 while being also formed of the conductive paths having an arbitrary shape connecting pairs of the layers, and the matrix bodies 3 are formed among the conductive paths having the arbitrary shapes configuring the PTC sections 1 on the insides of a pair of the layers of the PTC sections 1, and its manufacturing method are provided.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a resetter capable of withstanding repeated use having a clear structure, low resistance and excellent reproducibility, which is used for protecting batteries and personal computers from overheating and overcurrent. The present invention relates to a bull fuse element and a manufacturing method thereof.

[0002]

2. Description of the Related Art The spread of mobile phones has been remarkable all over the world, especially in Northern Europe and Japan, and the technological innovation of mobile phones has made great progress, especially in communication systems. The same is true for the advancement of mobile phone power supplies. The power of the mobile phone is
Naturally, batteries are used for better portability, but secondary batteries are almost always used in consideration of economy and environmental load. Secondary batteries are batteries that can be reused by charging and are widely used in electronic information devices such as personal computers in addition to mobile phones.

[0003] When a battery is used by mistake, the battery may be overheated or an overcurrent may flow into the battery.
Li batteries and the like which have a risk of explosion require some protection against these situations. As this protection means, a PTC element or a fuse is mainly used.

A PTC element has a PTCR characteristic (Positive Temperature Coefficient of Positive Temperature).
(Resistivity). The following examples are known for materials having PTCR characteristics.

According to JP-A-8-239485, a method for producing a conductive polymer element as a material having PTCR characteristics is proposed. The matrix phase is an organic polymer such as polyethylene, and the conductive phase dispersed therein is a conductive substance such as carbon black. A conductive polymer obtained by melt-molding a composition comprising these is a material having PTCR characteristics.
The conductive phase carbon black is uniformly dispersed as particles in the organic polymer that is the matrix phase, and the thermal expansion of the organic polymer when the temperature rises causes the conductive path of the carbon particles that are the conductive phase to be cut off. The resistance rises. Examples of blends composed of polyethylene and carbon black are shown to have PTCR properties.

However, the conductive polymer material is a polymer in which a matrix phase that expands by generating heat is a flammable substance, and has a problem in safety because of a possibility of fire. Furthermore, the rise of the specific resistance at the time of the PTCR characteristic expression,
It is somewhat slow and should be improved. In addition, the problem is that the material itself becomes large in large current applications, the resistance during normal conduction gradually increases with repeated use, and the withstand voltage characteristics deteriorate when the resistance is further reduced. is there.

[0007] The following example is also known for a material having another PTCR property. International Publication Number WO98 / 1
According to 1568, a PTC thermistor material is proposed. The matrix phase is polycrystalline ceramic, glass
It is a polycrystalline ceramic composite material, glass, or crystallized glass, and the conductive phase dispersed therein is a metal containing Bi as a main component. A material obtained by mixing and heat-forming a composition comprising these has PTCR characteristics. The metal having the conductive phase of Bi as the main component is uniformly dispersed as particles in the ceramic which is the matrix phase. By interrupting the conductive path of the metal as a component, the resistance suddenly increases. Further, in the example using a metal containing Bi as a main component, it is shown to have a PTCR characteristic. It is also shown that there is almost no characteristic change due to repetition.

However, polycrystalline ceramics, which is a matrix phase, and a metal mainly containing Bi, which is a conductive phase, are simply mixed, molded and fired, and the formation of conductive paths is stochastic. I have. For this reason, there are problems that the performance is not stable and there is anxiety leading to an accident, the resistance becomes higher than the theoretical value, and the variation among products increases as the product shape becomes smaller. Further, since there is a problem such as volatilization of metal components in the manufacturing process, a stable manufacturing method has not yet been established, and high cost is a major problem in practical use.

The biggest drawback is that the fuse must be replaced once it operates to protect it by fusing. Generally, protection of a Li-ion secondary battery is as follows.
Despite the double and triple protection, fuses are only suitable for final protection applications.

[0010]

DISCLOSURE OF THE INVENTION The present invention has been made in view of the above-mentioned conventional problems, and has as its object to have a clear conductive path, and to have any part when PTCR characteristics are exhibited. It is an object of the present invention to provide a resettable fuse element having high resistance, which is safe, has low resistance, and has stable product characteristics by a stable manufacturing method at a lower cost. The resettable fuse element is a fuse that can be used repeatedly.

Further, the object of the present invention is to make the specific resistance rise steeply when the PTCR characteristic is manifested, to have a lower resistance during steady-state energization, and to make the characteristic not fluctuate even when used repeatedly. An object of the present invention is to improve stable reproducibility, durability that can be repeatedly used many times, and the like.

[0012]

Means for Solving the Problems As a result of various studies to achieve the above object, the present inventors have made a conductive path of an arbitrary shape as a PTC portion in a current-carrying body, and It has been found that the above object can be achieved by expressing PTCR characteristics. It has also been found that the above object can be achieved by forming a plurality of fine through-holes in a thick ceramic sintered plate and pouring a metal into the current-carrying body to produce the current-carrying body.

That is, according to the present invention, there is provided a resettable fuse element having a PTCR characteristic including a current-carrying body through which a steady-state current flows and a matrix having a higher specific resistance than the current-carrying body. And a PTC portion, and the electrode portion is formed by a pair of opposing layers,
The PTC portion is formed by a pair of layers facing the electrode portion inside the pair of electrode portions, and is also formed by an arbitrary-shaped conductive path connecting the pair of layers. P inside the pair of layers
There is provided a resettable fuse element formed between conductive paths of an arbitrary shape constituting a TC portion. The shape of the conductive path is preferably a plurality of parallel substantially columnar shapes connecting the electrode portions.

In the case of a cylindrical conductive path, the ratio of the length in the direction connecting the pair of layers of the electrode portion to the diameter in the direction perpendicular to the length is preferably about 4: 1 or more. . When the diameter is relatively large with respect to the length, the conductive path, that is, the cross-sectional area of the PTC part increases, and even if the PTC part contracts, the conductive path is hard to be interrupted, and a good PT
It is not preferable because CR characteristics cannot be obtained.

Further, according to the present invention, there is provided a resettable fuse element having a PTCR characteristic composed of a current-carrying body through which a steady-state current flows and a matrix body having a higher specific resistance than the current-carrying body. And a PTC portion, and the electrode portion is formed by a pair of opposing layers, and is also formed by a plurality of parallel linear conductor portions that are close to each other from the pair of layers. Is formed in the middle of the conductor portion as a conductive path of an enormous portion connecting the conductor portion, and the matrix body has a conductor portion of a plurality of electrode portions inside a pair of layers of the electrode portion, and a plurality of conductor portions. There is provided a resettable fuse element formed between the enormous portions of the PTC portion. In the present invention, the shape of the expanded portion is preferably a cone.

In the present invention, the material of the electrode portion is P
Because it is difficult to make an alloy with Bi which is a TC part material,
It is preferable that the metal containing W or Mo as a main component is used, and the metal containing W or Mo as a main component has a particle diameter of 100 μm or less because resistance and heat generation during steady energization are suppressed. preferable. Further, the material of the PTC portion is preferably a metal mainly composed of Bi having a low melting point when formed into an alloy. Is preferably 100 μm or less. The matrix body is preferably made of ceramics because it does not ignite and is safe.

The resettable fuse element of the present invention
Even if the resistance value is 0.1Ω or less, sufficient withstand voltage and current capacity are realized, and it is suitably used, for example, for protection of secondary batteries for mobile phones. In particular, in a resettable fuse element having an enlarged conductive path, the resistance value is set to 0.01 Ω or less by devising the length of the conductor connecting the pair of electrodes and the enlarged part to be short. Is also possible.

Further, according to the present invention, a step of producing a ceramic green plate as a matrix body, a step of forming a plurality of fine through holes in the ceramic green plate, and a step of forming the ceramic green plate PTC at the specified position on the tie
A step of injecting a molten metal containing Bi as a main component as a part, a step of firing a ceramic unsintered plate into which the molten metal is injected to form an integral sintered body, and a step of mainly introducing the Bi of the sintered body. A step of polishing a metal surface as a component, a step of applying metal plating as an electrode portion to a metal surface mainly containing Bi of the sintered body, and a step of cutting the sintered body. And a method for manufacturing a resettable fuse element.

Furthermore, according to the present invention, a step of producing a ceramic sintered plate as a matrix body, a step of forming a plurality of fine through holes in the ceramic sintered plate,
A step of injecting a molten metal mainly composed of Bi as a PTC portion into a predetermined position of the ceramic sintered plate; a step of polishing a metal surface mainly composed of Bi of the ceramic sintered plate; A resettable fuse, comprising a step of applying metal plating as an electrode portion to a metal surface mainly containing Bi of the ceramic sintered plate and a step of cutting the ceramic sintered plate. A method for manufacturing a device is provided.

On the other hand, according to the present invention, a step of producing at least two ceramic unsintered plates as a matrix body, and a step of forming a plurality of ceramic unsintered plates so that holes are aligned with each of the at least two ceramic unsintered plates. A step of forming a fine through-hole, a step of forming a metal layer mainly composed of W or Mo as an electrode part in the through-hole, and a step of forming at least one ceramic unsintered plate with a central axis of the through-hole. A step of forming a hole in the shape of an enormous portion having an arbitrary shape, a step of injecting and solidifying a molten metal mainly containing Bi as a PTC portion into the hole of the arbitrary shape, and a step of melting and solidifying the Bi Polishing a metal surface mainly composed of: and bonding another ceramic unsintered plate to the side of the ceramic unsintered plate on which a hole of an arbitrary shape is formed, in accordance with the center axis of the through hole To make an integrated laminate And a step of firing the laminate to form an integrated sintered body, a step of applying metal plating so as to connect to a conductor of an electrode portion of the sintered body, and There is provided a method for manufacturing a resettable fuse element, comprising a step of cutting.

According to the present invention, on the other hand, a step of producing at least two ceramic sintered plates as a matrix body, and a step of forming a plurality of fine powders so that holes are aligned with each of the at least two ceramic sintered plates. Forming a through hole, and forming W or Mo in the through hole as a conductor of an electrode portion.
Forming a metal layer mainly composed of:
Forming a hole in the shape of an enlarged part of an arbitrary shape in accordance with the central axis of the through-hole in a plurality of ceramic sintered plates, and forming a molten metal mainly composed of Bi as a PTC part in the hole of the enlarged part. Injecting and solidifying; polishing at least one of the fused and solidified ceramic sintered plates a metal surface containing Bi as a main component; A step of joining another at least one ceramic sintered plate to the side where the hole is formed in accordance with the center axis of the through-hole to form an integrated laminate, and connecting to a conductor of an electrode portion of the laminate A method of manufacturing a resettable fuse element, comprising a step of applying a metal plating containing W or Mo as a main component and a step of cutting the laminate.

[0022]

BEST MODE FOR CARRYING OUT THE INVENTION Hereinafter, the present invention will be described in detail. A resettable fuse element according to the present invention is one in which an electric conductor in which a steady-state current flows is formed so as to penetrate through a ceramic sintered plate as a matrix body. The current-carrying body is composed of an electrode part and a PTC part.
There is a significant feature in that expression is performed only at a specific position in the TC region.

In the prior art, when a temperature rise such as heat generation due to an abnormal current or external heating occurs, even if the matrix phase thermally expands and a means for interrupting a conductive path in the conductive phase is used, Even when the phase is a means for heat-shrinking to interrupt its own conductive path, the conductive path is not a specific part of the conductive phase and is ambiguous. Whether or not to conduct is determined stochastically from the conductive particle diameter and the conductive particle interval. For this reason, the resistance becomes higher by at least an order of magnitude than the theoretical value, and since there is a large variation in characteristics among the products, there is always anxiety leading to an accident.

In the present invention, the PTC portion is formed as a pair of opposing layers and a conductive path having an arbitrary shape connecting between the layers, and the PT is formed only at the conductive path portion having an arbitrary shape.
The conduction path is clarified by expressing the CR characteristic, that is, by operating as a fuse. Also, the electrode portion is formed as a pair of opposing layers and a plurality of parallel linear conductor portions which are close to each other from between the layers, and the PTC portion is formed as a conductive path in the form of an arbitrarily large portion in the middle of this conductor portion, The conductive path is clarified also by expressing the PTCR characteristic only in this conductive path portion, that is, operating as a fuse.

In the present invention, in the resettable fuse element having no enormous portion of the conductive path, the shape of the conductive path may be, for example, a plurality of parallel substantially columnar shapes that are easy to manufacture and that connect the electrode portions. When a substantially cylindrical conductive path is used, the ratio between the length and the diameter of the substantially cylindrical conductive path needs to be approximately 4: 1 or more in order to obtain good PTCR characteristics. The increase in diameter with respect to length is due to P
This means that the cross-sectional area of the TC section is relatively large compared to the volume of the PTC section, so that even if the PTC section shrinks, the inconvenience that the conductive path is hard to be interrupted is likely to occur.

The material of the PTC part in the present invention is a metal containing Bi as a main component. A metal containing Bi as a main component has a low melting point and can exhibit PTCR characteristics around 150 ° C., which is suitable as a fuse. Further, the temperature at which PTCR characteristics are developed can be controlled by changing the composition and the composition of Bi as a main component.

Further, the metal containing Bi as a main component is
It is preferable that the particles have a particle diameter of 100 μm or less in order to improve reproducibility and durability as a fuse. When an overcurrent flows in the PTC portion, the temperature rises due to heat generation, the PTC portion shrinks, and the current is cut off due to an increase in conduction resistance. However, the metal particles mainly containing Bi are fine. In contrast, the stress applied to the adjacent matrix body when contracted and reduced in volume is less. If the matrix body is not deformed and is not broken, the possibility of causing melting and outflow of the metal mainly containing Bi at the time of heat generation is reduced. Can withstand more.

As described above, since the conductive path is clear and the conductive path is completely released during operation, abnormal temperature rise does not occur, and the metal mainly composed of Bi in the PTC portion melts and flows out. This is preferable because it contributes to reproducibility and durability.

In the present invention, the material of the electrode portion is W,
Alternatively, it is a metal containing Mo as a main component. The metal containing W or Mo as the main component hardly reacts with Bi, and does not cause the characteristic change and the performance deterioration due to the deterioration of the materials of the electrode portion and the PTC portion.

In the present invention, it is preferable that the matrix body be made of ceramics in order to improve safety, reproducibility, and durability. Ceramics have a low affinity for a metal containing Bi as a main component and are unlikely to react with each other and change in quality with each other, and thus do not cause characteristic fluctuations and performance deterioration due to material deterioration in the PTC portion. Also, since it is not a flammable substance, it does not ignite at the time of heat generation and is safe.

As an example of alteration due to a reaction with the surroundings,
When Bi is oxidized, its melting temperature changes, its characteristics change, and it stops conducting. Although this can be said to have a fail-safe characteristic, in order to exhibit stable performance, as described above, there is no affinity for the periphery, such as ceramics, metals containing W or Mo as a main component, and the like. It is preferable to use a material having low reactivity and difficult to react.

The resettable fuse element according to the present invention
Since the resistance value during energization can be suppressed to 0.1Ω or less and the current loss is small, it is suitably used for protection of secondary batteries for mobile phones and the like that require more power saving. In a resettable fuse element with a huge conduction path,
Since the expanded portion can exhibit sufficient PTCR characteristics, if the length of the conductor connecting the pair of layers of the electrode portion and the expanded portion is shortened, the resistance can be further reduced, and the resistance during energization is reduced to 0.1. 0
1 Ω or less can be realized.

Hereinafter, the present invention will be described with reference to the drawings.
FIGS. 1A and 1B show a resettable fuse according to an embodiment of the present invention, in which a plurality of thin linear conductive paths (hereinafter, referred to as linear portions 5) are formed in an electric conductor and specified. This shows an example of a resettable fuse element that exhibits PTCR characteristics in this portion. It is formed from an electric conductor comprising the electrode part 4 and the PTC part 1 and the matrix body 3,
The electrode portion 4 is formed by a pair of opposing layers,
The PTC portion 1 is formed inside a pair of electrode portions 4 by a pair of layers facing each other similarly to the electrode portion 4 and is also formed by a plurality of parallel linear portions 5 connecting the pair of layers. . The matrix body 3 is formed between a plurality of parallel linear portions 5 inside a pair of layers of the PTC portion 1.

FIG. 1A shows an energized state. In a steady state, a current flows from the electrode unit 4 through the PTC unit 1. The resistance is small because it flows simultaneously through the parallel linear portions 5 via the pair of layer portions. By manufacturing many linear portions 5, it is possible to reduce the resistance value in a steady state.

FIG. 1B shows an open state, that is, a state in which the fuse is blown.
The plurality of parallel linear portions 5 formed inside the pair of layers of the C portion 1 are cut and completely released. When an overcurrent occurs, heat is generated and the temperature rises. At this time, the metal containing Bi as a main component is shrunk at a plurality of parallel linear portions 5 that are mainly a part of the PTC portion 1, and the pair of layers side Pulled. Therefore, a gap 2 is formed in the conductive path, which is a plurality of parallel linear portions 5, and the current is cut off due to an increase in the conduction resistance. When the temperature decreases, the linear portion 5 recovers again and a current flows.

FIGS. 2A and 2B are diagrams according to the present invention.
One embodiment of a resettable fuse element in which a plurality of large cubic conductive paths (hereinafter, referred to as "enlarged portions 6") are formed in an electric conductor and PTCR characteristics are developed at the specified portions. This is an example in which the enlarged portion 6 is a cone. The electrode unit 4 is formed of a pair of opposing layers, and is formed of a pair of opposing layers, and is formed of a plurality of parallel linear shapes that are close to each other from the pair of layers. It is also formed by the conductor 7. The expanding part 6 is formed as a conductive path by connecting the conductor part 7 in the middle of the conductor part 7. Matrix body 3
Are inside the pair of layers of the electrode section 4 and the plurality of conductor sections 7
And between the enlarged part 6.

FIG. 2A shows an energized state. In a steady state, a current flows from the electrode section 4 through the expanding section 6.
The resistance is small because it flows simultaneously through the conductive paths, which are a plurality of enlarged portions 6, via the linear conductor portions 7 parallel to the pair of layer portions of the electrode 4. By manufacturing a large number of enlarged portions 6, it is possible to reduce the steady-state resistance value and to reduce the resistance value to 0.01Ω or less.

FIG. 2B shows an open state, that is, a state in which the fuse is blown, and when the PTCR characteristic is developed, a plurality of conductive paths, which are the bulging portion 6, are broken and completely released.
When an overcurrent occurs, heat is generated and the temperature rises. At this time, the metal mainly composed of Bi shrinks in a plurality of conductive paths that are mainly the enlarged portion 6, and the gap 2 is generated in the enlarged portion 6,
The current is cut off due to an increase in the conduction resistance. When the temperature drops, the bulging portion 6 recovers again and a current flows.

The enlarged portion 6 indicates a conical portion formed in the middle of the conductor portion 7 of the parallel fine through hole. In the resettable fuse element shown in FIGS. 2 (a) and 2 (b), the reason why the enlarged portion 6 is formed into a conical shape is that a large energization resistance during fuse operation can be obtained. FIG. 3 (a)
FIGS. 5A to 5C are comparative explanatory diagrams showing the amount of change in height for each shape when the PTC portion 1 of the resettable fuse element according to the present invention contracts in volume. 3A shows an example of a sphere, FIG. 3B shows an example of a cylinder, and FIG. 3C shows an example of a cone. FIG. 3C shows the largest change in height. In the example in which the metal mainly composed of Bi, which is the PTC portion 1, contracts by 3% in volume, the upper and lower sides are 15% in FIG.
In FIG. 3, a change in height was observed in the upper part 3%, and in FIG. It is preferable that the height is largely changed, that is, the gap 2 is large because the current-carrying resistance during the fuse operation increases.

FIGS. 4A to 4G show a plurality of thin linear conductive paths (hereinafter, referred to as linear portions 12) in an electric conductor which is an embodiment of the resettable fuse element according to the present invention. It is explanatory drawing which shows an example of the manufacturing method of the resettable fuse element which has this. The thick ceramic sintered plate 13 as a matrix body is prepared as a slurry or paste by mixing an appropriate binder, a plasticizer, a dispersant, a sintering aid, an organic solvent, and the like into ceramic powder, and preparing the slurry or paste. Using the paste, a ceramic unsintered plate having a predetermined thickness is obtained according to a doctor blade method, a calender method, a printing method, a reverse roll coater method, and the like, and further sintered to form a ceramic sintered plate 13. .

Next, a plurality of fine through holes 15 are formed in the ceramic sintered plate 13. The through hole 15 is a mold / N
It may be formed by C punching, excimer laser processing, or the like. In preparation for later cutting, a partition plate 17 is bonded to both surfaces of the ceramic sintered plate 13 for each product unit. Then, a molten metal 16 mainly composed of Bi is injected as a PTC portion into the through hole 15 and both surfaces of the ceramic sintered plate 13 and solidified. Next, Bi of the ceramic sintered plate 13
The surface of the metal 16 containing Bi as the main component is polished, and the metal 16 containing Bi as the main component of the ceramic sintered plate 13 is further polished.
Is plated with metal as an electrode part on the surface of the substrate. Finally, the ceramic sintered plate 13 is cut for each product and shipped.

A plurality of fine through-holes 15 are formed in a ceramic unsintered plate, and a partition plate 17 is bonded to both surfaces,
It is also possible to inject a molten metal 16 mainly containing Bi as a PTC portion into the through hole 15 and both surfaces. In this method, a firing operation is performed on the ceramic unsintered plate into which the molten metal 16 has been injected to obtain a sintered body. The firing temperature at this time differs depending on the matrix phase.

FIGS. 5A to 5F show a method of manufacturing a resettable fuse element having a plurality of linear portions 12 in an electric conductor, which is an embodiment of the resettable fuse element according to the present invention. It is explanatory drawing which shows another example. FIG.
This is almost the same as the manufacturing method shown in (g), except that the step of bonding the partition plates 17 to both surfaces of the ceramic sintered plate 13 is canceled, and the process of manufacturing the thick ceramic sintered plate 13 as a matrix body is performed instead. In this case, the projection 18 corresponding to the partition plate 17 is prepared in advance.

FIGS. 6A to 6G show a plurality of large arbitrarily-shaped cubic conductive paths (hereinafter referred to as an enlarged portion 11) in an electric conductor which is an embodiment of the resettable fuse element according to the present invention. FIG. 4 is an explanatory diagram showing an example of a method for manufacturing a resettable fuse element having a “resetable fuse element”. The thick ceramic sintered plate 13 as a matrix body is prepared as a slurry or paste by mixing an appropriate binder, a plasticizer, a dispersant, a sintering aid, an organic solvent, and the like into ceramic powder, and preparing the slurry or paste. Using the paste, a ceramic unsintered plate having a predetermined thickness is obtained according to a doctor blade method, a calender method, a printing method, a reverse roll coater method, and the like, and further sintered to form a ceramic sintered plate 13. . At least two ceramic sintered plates 13 are produced.

At least two ceramic sintered plates 13
Are formed with a plurality of fine through-holes so that the positions of the holes are matched. The through holes may be formed by die / NC punching, excimer laser processing, or the like. W in the through hole,
Alternatively, a metal containing Mo as a main component is injected and the conductor portion 1 of the electrode portion is formed.
9 is produced. Next, a hole in the shape of the enlarged portion 11 is formed in at least one of the two ceramic sintered plates 13 in accordance with the central axis of the conductor portion 19 of the electrode portion, and the hole in the shape of the enlarged portion 11 is formed. , A molten metal 16 mainly containing Bi as a PTC portion is injected and solidified, and the surface of the metal 16 is polished. At least one other ceramic sintered plate 13 is joined to and integrated with the side of the ceramic sintered plate 13 where the hole in the shape of the enlarged portion 11 is formed, in accordance with the central axis of the conductor portion 19 of the electrode portion. The laminate 20 is used. Next, W or M is connected so as to be connected to the conductor portion 19 of the electrode portion of the laminate 20.
Metal plating 14 containing o as a main component is applied. Finally, the laminate 20 is cut for each product and shipped.

A plurality of fine through holes are formed in the ceramic unsintered plate, and a metal containing W or Mo as a main component is injected into the through holes to form a conductor portion 19 of an electrode portion. A hole in the shape of the enlarged portion 11 is formed in accordance with the central axis of the conductor portion 19, and a molten metal 16 mainly composed of Bi is injected into the hole in the shape of the enlarged portion 11 as a PTC portion and solidified. Further, the surface of the metal 16 is polished to form a hole in the shape of the enlarged portion 11 of the ceramic unsintered plate, and at least one other ceramic is aligned with the central axis of the conductor portion 19 of the electrode portion. It is also possible to join the unsintered plates to form an integrated laminate 20. In this method, a firing operation is performed on the laminate 20 to obtain a sintered body. The firing temperature at this time differs depending on the matrix phase.

As described above, according to the present invention, through-hole processing, Bi-based metal injection, polishing, plating,
By a very clear and simple processing means of cutting and bonding if necessary, a resettable fuse element with lower resistance and larger capacity having a constant PTCR characteristic can be stably manufactured.

[0048]

EXAMPLES Next, the present invention will be described in more detail with reference to examples, but the present invention is not limited to these examples.

Example 1 Using a paste obtained by mixing a binder, a plasticizer, a dispersant, a sintering aid, and an organic solvent with a ceramic powder, a ceramic non-sintered plate was formed according to a doctor blade method and fired. A ceramic sintered plate was obtained.
0.3mm diameter x 2mm length on the ceramic sintered plate
After forming a plurality of through holes by NC punching, a partition plate is adhered to both surfaces of the ceramic sintered plate, and a Bi alloy is melted and injected as a PTC portion into the through holes and both surfaces of the ceramic sintered plate to be solidified. I let it. Then, the solidified Bi
The surface of the alloy was polished, and the surface of the Bi alloy was further subjected to W plating as an electrode portion. Finally, the ceramic sintered plate was cut for each product to obtain a resettable fuse element. The resistance value of each of the manufactured resettable fuse elements was measured, and the PTCR characteristics were examined. Table 1 shows the results.

(Example 2) A plurality of through-holes having a diameter of 0.3 mmφ and a length of 2 mm were formed in a ceramic unsintered plate by NC punching, and a partition plate was bonded to both surfaces of the ceramic unsintered plate. A Bi alloy as a PTC portion was melted and injected into both surfaces of the through-hole and the ceramic unsintered plate and solidified, and then fired to obtain a ceramic sintered plate. Otherwise, a resettable fuse element was manufactured in the same manner as in Example 1. A resettable fuse element having a through hole having a diameter of 0.3 mmφ × 1.3 mm in length and a diameter of 0.1 mmφ × 0.5 mm in length was produced in the same manner, and the resistance of each element was measured to evaluate the PTCR characteristics. Examined. Table 1 shows the results.

Example 3 Two ceramic sintered plates were produced in the same manner as in Example 1. After forming a plurality of through-holes having a diameter of 0.3 mmφ and a length of 2 mm in the two ceramic sintered plates by NC punching so that the positions of the through-holes are aligned, a W alloy is melted and injected into the through-holes. It was solidified to form a conductor portion of the electrode portion. Next, a conical hole is formed in one of the two ceramic sintered plates in accordance with the central axis of the conductor portion of the electrode portion.
The i alloy was melted, poured and solidified, and the surface of the Bi alloy was polished. Another ceramic sintered plate was joined to the side of the ceramic sintered plate on which the hole of the conical body was formed in accordance with the central axis of the conductor of the electrode portion, to obtain an integrated laminate. Next, W plating was performed by connecting to the conductor of the electrode part of the laminate. Finally, the laminate was cut for each product to obtain a resettable fuse element. A resettable fuse element having a through hole having a diameter of 0.3 mmφ and a length of 0.5 mm was produced in the same manner, and the resistance of each element was measured to examine the PTCR characteristics. Table 1 shows the results.

(Example 4) A plurality of through holes having a diameter of 0.3 mmφ and a length of 2 mm were formed in two ceramic unsintered plates by NC punching so that the positions of the through holes were aligned. The W alloy was melted, injected and solidified to form a conductor portion of the electrode portion. Next, a conical hole is formed in one of the two ceramic unsintered plates in accordance with the central axis of the conductor portion of the electrode portion.
The i alloy was melted, poured and solidified, and the surface of the Bi alloy was polished. On the side of the ceramic unsintered plate where the hole of the cone was formed, another ceramic unsintered plate was joined to the center axis of the conductor of the electrode portion to obtain an integrated laminate. . Next, the laminate was fired to obtain a sintered body. Otherwise, a resettable fuse element was manufactured in the same manner as in Example 3. A resettable fuse element with a through hole of 0.3 mm in diameter x 0.5 mm in length was also manufactured,
Each resistance value was measured, and the PTCR characteristics were examined. Table 1 shows the results.

(Comparative Example 1) A through hole having a diameter of 0.3 mmφ
X A resettable fuse element was prepared in the same manner as in Example 1 except that the length was 0.5 mm, and the resistance value was measured.
The PTCR characteristics were examined. Table 1 shows the results.

(Comparative Example 2) A through hole having a diameter of 0.3 mmφ
× length 1.0 mm, and diameter 0.3 mmφ × length 0.5
A resettable fuse element was prepared in the same manner as in Example 2 except that the thickness was changed to mm, the resistance value was measured, and the PTCR characteristics were examined. Table 1 shows the results.

(Consideration) Using a ceramic substrate, a resettable fuse element was formed three-dimensionally by extremely clear and simple processing means such as through-hole processing, metal injection, polishing, plating, and cutting. Both the method of processing after firing and the method of processing a fired ceramic substrate resulted in a resettable fuse element exhibiting excellent PTCR characteristics. A preferable manufacturing condition is a case where there is a conical expanded portion and the through hole size, that is, the conductor portion is thicker and shorter, having a diameter of 0.3 mmφ and a length of 0.5 mm. It was confirmed that the resistance value was suppressed low in inverse proportion to the size of the through hole, that is, the diameter of the conductor portion, and increased in proportion to the length thereof. The method of processing the ceramic substrate after firing or the method of processing the fired ceramic substrate hardly affected the resistance value. On the other hand, with regard to the PTCR characteristics, better results were obtained when there was an enormous portion than when there was no such portion.
When there is no enormous part, the length / diameter (L / D) of the through hole
And good results were obtained when L / D ≧ 4. This is presumably because the larger the diameter of the through-hole, the larger the contact area at the boundary of the through-hole, and the smaller the L, the smaller the volume of change becomes, making it difficult to cut the conductive path. You.

[0056]

[Table 1]

[0057]

As described above, according to the present invention, a resettable fuse element having a clear conductive path and completely cutting off the conductive path when the PTCR characteristic is developed and causing no leakage current can be obtained by a clear procedure. Since it is manufactured using a simple processing means, the effects of improving safety and reducing manufacturing costs can be obtained. In addition, the rise of the specific resistance when the PTCR characteristic is manifested becomes steeper, the resistance at the time of steady energization becomes lower, the characteristic reproducibility does not fluctuate even when used repeatedly, and the reproducibility is improved. It also has the effect of improving durability.

[Brief description of the drawings]

FIG. 1 is a view showing an embodiment of a resettable fuse element according to the present invention, in which a plurality of thin linear conductive paths are formed in an electric conductor, and a PTCR characteristic is developed in a specified portion thereof. It is an explanatory view showing an example of an element,
FIG. 1A shows an energized state, and FIG. 1B shows an open state (a state in which a fuse is blown).

FIG. 2 shows an embodiment of the resettable fuse element according to the present invention, in which a conductive path of an enlarged portion of a cone is formed between a plurality of parallel linear conductors in an electric conductor and specified. FIG. 2A is an explanatory view showing an example of a resettable fuse element that exhibits PTCR characteristics in this portion. FIG. 2A shows an energized state, and FIG. 2B shows an open state (a state in which a fuse is blown).

FIG. 3 is a comparative example explanatory diagram showing the amount of change in height when the volume shrinks due to the shape of the enormous portion of the resettable fuse element according to the present invention. FIG. 3 (a) is an example of a sphere, FIG.
3B shows an example of a cylindrical body, and FIG. 3C shows an example of a conical body.

FIG. 4 is an explanatory view showing an example of a method for manufacturing a resettable fuse element having a plurality of thin linear conductive paths in an electric conductor, which is an embodiment of the resettable fuse element according to the present invention. (A) is a process for preparing a ceramic sintered plate,
FIG. 4B shows a fine through-hole forming step, FIG. 4C shows a partition plate bonding step, FIG. 4D shows a Bi-based metal injection step, and FIG.
4E shows a Bi-based metal surface polishing step, FIG. 4F shows a W or Mo-based metal plating step, and FIG. 4G shows a cutting step.

FIG. 5 is an explanatory view showing another example of a method for manufacturing a resettable fuse element having a plurality of thin linear conductive paths in an electric conductor, which is one embodiment of the resettable fuse element according to the present invention. 5 (a) is a process for preparing a ceramic sintered plate, FIG. 5 (b) is a process for forming fine through holes, and FIG.
5D is a Bi-based metal surface polishing step, FIG. 5E is a W or Mo-based metal plating step, FIG.
(F) shows a cutting step.

FIG. 6 is an explanatory view showing an example of a method of manufacturing a resettable fuse element having a conductive path of a conical body as a plurality of enlarged portions in an electric conductor, which is an embodiment of the resettable fuse element according to the present invention; FIG. 6A is a process for producing a ceramic sintered plate (a substrate having an electrode portion already formed in a fine through-hole), FIG. 6B is a process for forming a hole (for example, a conical hole) in the shape of an enlarged portion, and FIG. c) is a Bi-based metal implantation step, and FIG.
6 (e) shows a ceramic sintered plate laminating step, FIG. 6 (f) shows a W or Mo based metal plating step, and FIG. 6 (g) shows a cutting step.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... PTC part (Bi system metal), 2 ... air gap, 3 ... matrix body (ceramics), 4 ... electrode part (W or Mo system metal), 5 ... linear part (PTC part), 6 ... bulge part ( PTC
Part), 7: conductor part, 11: expanded part, 12: linear part, 13
... Ceramic sintered plate, 14 ... Metal plating (W or M
o), 15: through-hole, 16: metal (Bi-based), 17: partition plate, 18: projection, 19: conductor, 20: laminate.

 ──────────────────────────────────────────────────続 き Continued on the front page (72) Inventor Shigeki Hayashi 2-56, Suda-cho, Mizuho-ku, Nagoya, Aichi Prefecture Inside Nihon Insulator Co., Ltd. (72) Inventor Akimasa Ichikawa 2-56, Suda-cho, Mizuho-ku, Nagoya-shi, Aichi Prefecture No. Japan Insulator Co., Ltd. F-term (reference) 5E034 AA07 AB01 AC11 DB01 DC05 FA02

Claims (16)

[Claims] 1. A PTCR comprising an electric conductor through which a constant current flows, and a matrix having a higher specific resistance than the electric conductor.
A resettable fuse element having characteristics, wherein the conductor is constituted by an electrode portion and a PTC portion, wherein the electrode portion is formed by a pair of opposing layers, and wherein the PTC portion is formed by a pair of the electrode portions. Is formed by a pair of layers facing each other similarly to the electrode portion, and is also formed by a conductive path of an arbitrary shape connecting the pair of layers, and the matrix body is formed by a pair of layers of the PTC portion. A resettable fuse element formed between conductive paths of an arbitrary shape constituting the PTC portion inside the fuse element. 2. A PTCR comprising an electric conductor through which a constant current flows, and a matrix having a higher specific resistance than the electric conductor.
A resettable fuse element having characteristics, wherein the current-carrying body is constituted by an electrode portion and a PTC portion, and the electrode portion is formed by a pair of opposing layers and is close to each other from the pair of layers. The PTC portion is formed in the middle of the conductor portion as a conductive path of an enormous portion having an arbitrary shape connecting the conductor portion, and the matrix is formed by a plurality of parallel linear conductor portions. A resettable fuse element, wherein the body is formed inside the pair of layers of the electrode portion and between the conductor portions of the plurality of electrode portions and the plurality of PTC portions. 3. The conductive path having an arbitrary shape is a plurality of parallel, substantially cylindrical conductive paths.
2. The resettable fuse element according to item 1. 4. In the substantially columnar conductive path, a ratio of a length in a direction connecting the pair of layers of the electrode portion to a diameter in a direction perpendicular to the length is approximately 4: 1 or more. The resettable fuse element according to claim 3, wherein: 5. The resettable fuse element according to claim 2, wherein the arbitrarily-shaped enlarged portion is a cone. 6. The resettable fuse element according to claim 1, wherein a material of said electrode portion is a metal containing W or Mo as a main component. 7. The resettable fuse element according to claim 6, wherein the metal containing W or Mo as a main component of the electrode portion has a particle diameter of 100 μm or less. 8. The resettable fuse element according to claim 1, wherein the material of the PTC portion is a metal containing Bi as a main component. 9. The resettable fuse element according to claim 8, wherein the metal mainly composed of Bi in the PTC portion has a particle diameter of 100 μm or less. 10. The resettable fuse element according to claim 1, wherein the matrix body is made of a ceramic. 11. The resettable fuse element according to claim 1, wherein a resistance value when energized is 0.1 Ω or less. 12. The resettable fuse element according to claim 1, wherein a resistance value when energized is 0.01 Ω or less. 13. A non-sintered ceramic plate that forms a matrix body having a high specific resistance and no current flow, a step of forming a plurality of fine through holes in the non-sintered ceramic plate; A predetermined position of the sintered plate is formed by a pair of opposing layers inside the pair of opposing electrode portions similarly to the electrode portions, and is also formed by a conductive path of any shape connecting the pair of layers. A step of injecting a molten metal containing Bi as a main component as a PTC portion to be formed, a step of firing the ceramic unsintered plate into which the molten metal has been injected to form an integrated sintered body, Polishing a metal surface mainly composed of Bi as a main body; and W or Mo as an electrode portion formed by a pair of opposing layers on the metal surface mainly composed of Bi of the sintered body. Based on gold A step of plating, the manufacturing method of resettable fuse elements, characterized in that it comprises the step of cutting said sintered body. 14. A step of preparing a ceramic sintered plate that forms a matrix body having a high specific resistance and no current flow, forming a plurality of fine through holes in the ceramic sintered plate, A PTC formed at a predetermined position by a pair of layers facing the electrode section inside the pair of electrode sections facing each other, and also formed by a conductive path of an arbitrary shape connecting the pair of layers. As a part, a step of injecting and solidifying a molten metal containing Bi as a main component, a step of polishing a metal surface containing Bi as a main component of the ceramic sintered plate, and a process of polishing the Bi of the ceramic sintered plate. A step of applying a metal plating mainly containing W or Mo as an electrode part formed by a pair of opposing layers to a metal surface as a component, and a step of cutting the ceramic sintered plate. Method for producing a resettable fuse element characterized by comprising Nde. 15. A ceramic non-sintered plate having a high specific resistance and forming a matrix body through which no current flows is prepared, and the position of the hole is adjusted to each of the at least two ceramic non-sintered plates. Forming a plurality of fine through-holes, and the through-holes are formed by a pair of layers facing each other, and a plurality of parallel linear conductors adjacent to each other from the pair of layers. W as an electrode portion to be formed,
Or a step of forming a metal layer containing Mo as a main component; and forming at least one of the at least two ceramic unsintered plates with a hole having an arbitrarily large shape in accordance with the central axis of the through hole. Forming a PTC portion connecting the conductor portion in the middle of the conductor portion into a hole in the shape of the expanded portion, and solidifying by injecting a molten metal containing Bi as a main component; Polishing the metal surface mainly composed of Bi of the at least one ceramic unsintered plate, and expanding the at least one ceramic unsintered plate which has been subjected to hole processing in the form of an enlarged portion. A step of joining another at least one ceramic unsintered plate to a laminated body in accordance with the central axis of the through-hole on the side where the hole in the shape of the part is formed; and Firing to form an integrated sintered body; W is an electrode part formed of a pair of opposing layers on a metal surface mainly composed of Bi of the body and formed by a plurality of parallel linear conductor parts adjacent to each other from the pair of layers. Or a step of applying a metal plating containing Mo as a main component, and a step of cutting the sintered body. 16. At least two ceramic sintered plates forming a matrix body having a high specific resistance and no current flow are prepared, and a plurality of ceramic sintered plates are arranged so that holes are aligned with each of the at least two ceramic sintered plates. Forming a fine through-hole; forming a metal layer containing W or Mo as a main component as an electrode portion formed by a pair of opposing layers in the through-hole; On one of the ceramic sintered plates,
Forming a hole in the shape of an enlarged portion of an arbitrary shape in accordance with the central axis of the through hole; and forming the hole in the shape of the enlarged portion as a PTC portion connecting the conductor portion to the middle of the conductor portion. Injecting and solidifying a molten metal as a main component; and B of at least one of the at least two ceramic sintered plates.
polishing a metal surface containing i as a main component; and forming the through hole on the side of the at least one ceramic sintered plate on which the hole in the shape of the enlarged portion is formed. A step of joining another at least one ceramic sintered plate to form a laminated body in accordance with the central axis of the hole, and a pair of opposed metal surfaces mainly composed of Bi of the laminated body. A step of applying metal plating as an electrode part formed of a plurality of layers and also formed by a plurality of parallel linear conductor parts adjacent to each other from the pair of layers, and a step of cutting the laminate. A method for manufacturing a resettable fuse element, comprising: