Electronic component, and method for manufacturing the same

An electronic component is provided in which: impact-absorbing layers are provided so as to cover at least the corner portions of both end portions of a base which is made of an insulating mixture of ceramic and glass; a conductive film is formed so as to cover the surface of these impact-absorbing layers and the surface of the base; the portions of this conductive film which cover the surfaces of the impact-absorbing layers are formed into electrodes; and a resistance-adjusting groove is provided in an other portion of the conductive film than the portions serving as the electrodes.

TECHNICAL FIELD

The present invention relates to an electronic component which is used for various kinds of electronic equipment, and a manufacturing method for the same.

BACKGROUND ART

A conventional electronic component of this type will be described with reference toFIGS. 4A and 4B.FIG. 4Ais a perspective view of a circuit protective element which is an example of the conventional electronic component.FIG. 4Bis a sectional view of the circuit protective element, seen along an A-A line inFIG. 4A.

As shown inFIGS. 4A and 4B, the circuit protective element is configured by: a base1; a conductive film2; a protective film5; and a plating layer7. The base1is shaped like a pillar, such as a column and a prism. It is made of any of ceramic, glass, and a mixture of ceramic and glass, which have an insulation characteristic. The conductive film2is made of copper, silver, nickel or the like. It is formed over the entire surface of the base1. An electrode6is formed by each of the portions of the conductive film2which are located at both end portions of the base1. A plating layer7is formed on the surface of the electrode6. The protective film5is made of epoxy resin or the like. It is formed so as to cover the portion of the conductive film2's surface except its portions located at both end portions of the base1.

A portion of the conductive film2is cut off by means of laser irradiation or the like. Thereby, a resistance-adjusting groove3is created in the conductive film2. It makes substantially one turn so that its tips overlap each other. The region between the portions in which the tip portions of the resistance-adjusting groove3overlap each other is a narrow portion4. As an electronic component which has such a groove, for example, there is a chip component which is disclosed in Japanese Patent Laid-Open No. 7-307201 specification.

Herein, the conductive film2is a portion which fulfills the electrical function of the circuit protective element. For example, if an electronic component is a resistor, it becomes a resistant body. In the case of the circuit protective element shown inFIGS. 4A and 4B, it turns into a fusing portion with a fusing function. In this case, if an over-current beyond a certain level is applied, the narrow portion4provided in the conductive film2generates heat. Thereby, it is melted and fused. This breaks the current which is applied on the circuit protective element.

Next, a manufacturing method will be described for the above described circuit protective element. First, over the whole surface of the base1, the conductive film2is formed by means of plating. In this case, the electrode6is formed by the conductive film2located at both end portions of the base1.

Sequentially, the conductive film2is irradiated with a laser beam to cut off a portion of the conductive film2. Thereby, the resistance-adjusting groove3is formed which has substantially one turn so that its tips overlap each other. At this time, the narrow portion4is formed within the region between the overlapped portions in the tip portions of the resistance-adjusting groove3.

Next, the protective film5made of epoxy resin or the like is formed to cover the surface of the conductive film2other than the portions located at both end portions of the base1. Finally, the plating layer7is formed on the surface of the electrode6.

In the circuit protective element which is manufactured in this way, a resistance value is measured in its manufacturing process, or the resistance-adjusting groove3is formed. In order to take such a measurement, the circuit protective element needs to be held. A chuck is pressed against the electrode6so as to come into contact with it. Thereby, the circuit protective element can be held.

At this time, if the contact resistance between the chuck and the electrode6becomes greater, the contact resistance at this portion may adversely affect the measurement of a resistance value. This makes it impossible to adjust the resistance value precisely. Therefore, the contact resistance between the chuck and the electrode6has to be made as low as possible. In order to reduce the contact resistance between the chuck and the electrode6, the chuck needs to be pressed on the electrode6by a strong force.

On the other hand, in the above described circuit protective element, the conductive film2is formed on the entire surface of the base1. Thereby, the conductive film2is united with the electrode6which is located at both end portions of the base1. In this case, the conductive film2and the electrode6are continuously formed, thus helping stabilize their electrical and mechanical connection.

However, if the conductive film2and the electrode6are continuously united, then depending upon the circuit protective element's resistance value, the conductive film2becomes thinner and the electrode6also thins down. At this time, in order to lower the contact resistance between the chuck and the electrode6, the chuck is pressed against the electrode6by a strong force. Then, the base1cannot absorb all the mechanical impact at the time when it is pressed, and thus, the corner portions at both end portions of the base1may be chipped. This is because the base1is made of any of ceramic, glass, and a mixture of ceramic and glass. If the circuit protective element which has such a chip in its corner portions is mounted on a printed board or the like, its stable electrical connection cannot be obtained. Hence, the circuit protective element with any chips in the corner portions has to be removed, thus deteriorating its yield when manufactured.

DISCLOSURE OF THE INVENTION

It is an object of the present invention to provide an electronic component and its manufacturing method in which even if a chuck is pressed against an electrode located on both end-portion sides of a base by a strong force for the purpose of holding the electronic component, then the corner portions at both end portions of the base can be prevented from being chipped, and thus, its yield rate can be improved.

An electronic component according to an aspect of the present invention electronic component includes: an insulating base; an impact-absorbing layer which is formed so as to cover at least the corner portions of both end portions of the base; and a conductive film which is formed so as to cover at least a portion of the surface of the base and the surface of the impact-absorbing layer.

In the above described electronic component, even if a mechanical impact is given to both end portions of the base when the electronic component is held, this mechanical impact can be absorbed into the impact-absorbing layer. Therefore, in order to hold the electronic component, even if a chuck is pressed, by a strong force, on an electrode located on both end-portion sides of the base, then the corner portions at both end portions of the base can be hindered from being chipped. This helps enhance its yield.

An electronic-component manufacturing method according to another aspect of the present invention includes: a first process of forming an impact-absorbing layer so as to cover at least the corner portions of both end portions of an insulating base; and a second process of forming a conductive film so as to cover at least a portion of the surface of the base and the surface of the impact-absorbing layer.

In the above described electronic-component manufacturing method, an impact-absorbing layer is formed so as to cover at least the corner portions of both end portions of an insulating base. Thereafter, a conductive film is formed so as to cover at least a portion of the surface of the base and the surface of the impact-absorbing layer. Therefore, the impact-absorbing layer can be formed between both end portions of the base and the conductive film. As a result, even if a mechanical impact is given to both end portions of the base when the electronic component is held, this mechanical impact can be absorbed into the impact-absorbing layer. Therefore, in order to hold the electronic component, even if a chuck is pressed, by a strong force, on an electrode located on both end-portion sides of the base, then the corner portions at both end portions of the base can be hindered from being chipped. This helps enhance its yield. Besides, the impact-absorbing layer is formed before the conductive film is formed. Therefore, when the impact-absorbing layer is formed, the conductive film which is an element assembly of the electronic component can be kept from being damaged. This prevents the characteristics of an electric component from being deteriorated.

BEST MODE FOR IMPLEMENTING THE INVENTION

Hereinafter, a circuit protective element according to an embodiment of the present invention will be described with reference to the drawings.FIG. 1Ais a perspective view of the circuit protective element according to the embodiment of the present invention.FIG. 1Bis a sectional view of the circuit protective element, seen along an A-A line inFIG. 1A. Herein, a circuit protective element will be described below as an example of the electronic component. However, the electronic component to which the present invention is applied is not limited especially to this example. Hence, it can be similarly applied to various chip components or the like.

The circuit protective element shown inFIGS. 1A and 1Bis configured by: a base11; an impact-absorbing layer12; a conductive film13; a protective film17; and a plating layer18. The base11is made of an insulating mixture of ceramic and glass. It is shaped like a prism, and its section at both ends is thicker than that in the center as if it were an iron dumbbell.

The impact-absorbing layer12is made of copper which is a ductile metallic material. It is formed by means of electro-less plating with copper, on the entire surface of both end portions of the base11, or on both end surfaces of the base11and on side surfaces which extend out from both end surfaces. Herein, ductility means an object's property of the object itself stretching without being destroyed.

In order to configure the conductive film13, a metallic film is formed by a sputtering method using titanium and copper. Then, it is plated with nickel, copper and gold in order. This multi-layer film covers the base11and the whole surface of the impact-absorbing layer12. In the conductive film13, the portion which covers the surface of the impact-absorbing layer12is used as an electrode14.

The portion of the conductive film13other than the portions located on both end-portion sides of the base11, for example, a portion of its middle portion, is helically cut off using a trimming method such as laser irradiation. Thereby, a resistance-adjusting groove15is formed which has substantially one turn so that its tips overlap each other at a predetermined interval. At this time, a narrow portion16is formed in the region between the portions in which the tip portions of the resistance-adjusting groove15overlap each other. In the narrow portion16, a fusing portion is formed which functions as a fuse. Thereby, if an over-current beyond a certain level is applied on the circuit protective element, the narrow portion16provided in the conductive film13generates heat. Then, it is melted and fused, thus breaking the current which is given to the circuit protective element.

The protective film17is made of epoxy resin or the like. It is formed to cover the entire surface of the middle portion of the conductive film13. Thereby, it protects the portion except the conductive film13located on both end-portion sides of the base11. The plating layer18is made of a nickel plating layer and a tin plating layer. It is formed so as to cover the portion of the conductive film13which covers the surface of the impact-absorbing layer12, or the surface of the electrode14. Herein, inFIG. 1A, the protective film17is omitted so that the resistance-adjusting groove15and the narrow portion16can be clearly shown.

As described above, in this embodiment, the impact-absorbing layer12is provided so as to cover at least the corner portions of both end portions of the base11which is made of a brittle material which is an insulating mixture of ceramic and glass. Then, the conductive film13is formed so as to cover the impact-absorbing layer12and the surface of the base11. In the conductive film13, the portion which covers the surface of the impact-absorbing layer12is used as the electrode14.

Therefore, when a resistance value is measured, or when the resistance-adjusting groove15is formed, in order to hold the circuit protective element, even if a chuck100is pressed, by a strong force, against the electrode14located on both end-portion sides of the base11, then the impact-absorbing layer12provided between both end portions of the base11and the electrode14can absorb a mechanical impact at the time when it is pressed. Thereby, the corner portions of both end portions of the base11can be hindered from being chipped, thus improving its yield rate.

In addition, copper which is a ductile metallic material is used as the impact-absorbing layer12. Therefore, the above described mechanical impact can be certainly absorbed. Besides, the protective film17is provided on the surface of the conductive film13so that it covers at least the resistance-adjusting groove15. Thereby, the resistance-adjusting groove15can also be certainly protected.

Furthermore, the plating layer18made of a nickel plating layer and a tin plating layer is formed on the surface of the conductive film13located on both end-portion sides of the base11. Therefore, the surface mounting of the circuit protective element can be conducted, thus making smaller and thinner a circuit or the like which the circuit protective element is mounted.

Herein, the three-dimensional shape of the base11is not limited especially to the above described example. Another shape but a prism, for example, a columnar shape, a sheet-like shape or the like may also be used. Moreover, without changing its section's thickness at both ends from that in the center, the base11whose section has the same thickness from one of its ends up to the other may also be used. In addition, the sectional shape of the base11is not limited especially to the above described example. Various shapes can also be used, such as a regular polygon, a circle, a rectangle and an ellipse. Furthermore, the material of the base11is not limited especially to the above described example, either. A single insulating material such as ceramic and glass may also be used. The present invention can be suitably used for various insulating brittle materials.

Herein, the method of forming the impact-absorbing layer12is not limited especially to the above described example, either. Various formation methods, such as another plating method, a sputtering method and a printing method, can also be used. Furthermore, the material of the impact-absorbing layer12is not limited especially to the above described example, either. A ductile metallic material, such as gold, silver, platinum, nickel, chromium, palladium and an alloy of these, can also be used. Moreover, the portion of the base11in which the impact-absorbing layer12is formed is not limited especially to the above described example, either. The impact-absorbing layer12can be provided in another portion, as long as it coves at least the corner portions of both end portions of the base11which is easily chipped by a mechanical impact, or the portions (i.e., the edge portions of both end portions) where the end surfaces of the base11intersect the side surfaces which extend from the end surfaces.

The portion in which the conductive film13is formed is not limited especially to the above described example, either. There is no need to cover the portion except the electrode14located on both end-portion sides of the base11, or the whole surface of the middle portion of the base11. It may also be formed so as to cover only a portion of the surface of the middle portion of the base11, or the portion where a current concentrated portion is formed which becomes a fusing portion that embodies a fusing function. In that case, it is continuously united with the electrode14located on both end-portion sides of the base11. In addition, the material and formation method of the conductive film13are not limited especially to the above described example, either. Various conductive films can be used: only a metallic film is used which is formed by a sputtering method using titanium and copper; a multi-layer film is used which is formed by plating this metallic film with one or two that are chosen from among nickel, copper, gold, silver and the like; or a metallic film is used which is formed by plating this metallic film with one or more that are chosen from among nickel, copper, gold, silver and the like. A choice among these conductive films can be arbitrarily made according to what an electric component is used for. The usage purpose includes, for example: determining a resistance-value range; inhibiting the surface of the conductive film13from oxidizing; prompting the narrow portion16made of the conductive film13to be melted and fused; storing the heat which is generated at the narrow portion16; and the like.

The shape of the resistance-adjusting groove15is not limited especially to the above described example, either. Various shapes can also be used, for example, a resistance-adjusting groove which is a little short of substantially one turn is formed in the conductive film13, so that the tips of the groove face each other at an interval and do not overlap each other. Then, the region between the tip portions of the resistance-adjusting groove may also be used as a narrow portion which makes up a fusing portion. Furthermore, a resistance-adjusting groove can be formed in the conductive film13, so that it makes several turns around the base11. Thereby, it can also be as an electronic component such as an inductor and a resistor. Moreover, the method of forming the resistance-adjusting groove15is not limited especially to the above described example, either. A narrow portion which makes up a fusing portion may also be formed by forming a notch in the conductive film13by a mechanical cutting method using a trimming blade or the like.

In addition, the material of the protective film17is not limited especially to the above described example, either. Another resin may also be used, such as a phenol resin, a polyimide resin and a silicone resin. Besides, a denatured resin of each of these, also including an epoxy resin, may also be used. Furthermore, the position in which the protective film17is formed is not limited especially to the above described example, either. It does not necessarily cover the entire surface of the middle portion of the conductive film13, as long as it covers at least the position where the resistance-adjusting groove15is formed.

Next, the manufacturing method for the circuit protective element shown inFIGS. 1A and 1Bwill be described in further detail.FIGS. 2A to 2FandFIGS. 3A to 3Fillustrate a manufacturing process for explaining the manufacturing method of the circuit protective element shown inFIGS. 1A and 1B. Herein,FIGS. 2A,2C,2E andFIGS. 3A,3C,3E are perspective views of the circuit protective element shown inFIGS. 1A and 1Bin each manufacturing process.FIGS. 2B,2D,2F andFIGS. 3B,3D,3F are sectional views of the circuit protective element, seen along the A-A line inFIGS. 2A,2C,2E andFIGS. 3A,3C,3E.

First, with reference toFIGS. 2A and 2B, a resist film19is formed on the whole surface except both end portions of the base11which is made of an insulating mixture of ceramic and glass. Next, the impact-absorbing layer12made of copper is formed by electro-less plating, so that it covers the whole surface of both end portions of the base11other than the resist film19. Herein, in the case where the impact-absorbing layer12or the conductive film13is formed by electro-less plating, preferably, in advance, the entire surface of the base11should be etched and undergo an activation treatment which has a catalytic action for electro-less plating.

Sequentially, as shown inFIGS. 2C and 2D, the resist film19is removed from the base11. At this time, the resist film19and the portion of the impact-absorbing layer12which adheres to the resist film19are simultaneously removed. As a result, the impact-absorbing layer12remains only in both end portions of the base11. Hence, in its portion other than this, the surface of the base11is exposed.

Next, as shown inFIGS. 2E and 2F, the conductive film13is formed so as to cover the entire surface of the portion of the base11which is exposed by removing the resist film19and the portion of the impact-absorbing layer12that adheres to the resist film19at the same time, as well as the whole surface of the impact-absorbing layer12. As the conductive film13, a metallic film is formed by a sputtering method using titanium and copper. Then, it is plated with nickel, copper and gold in order. At this time, in the conductive film13, the portion which covers the surface of the impact-absorbing layer12is used as the electrode14. Thereby, the conductive film13is united with the electrode14which is located at both end portions of the base11. This makes the conductive film13and the electrode14continuous. In this case, the conductive film13and the electrode14are continuously formed, thus helping stabilize the electrical and mechanical connection of the conductive film13to the electrode14.

Sequentially, as shown inFIGS. 3A and 3B, a portion of the conductive film13is cut off by means of laser irradiation. Thereby, the resistance-adjusting groove15is formed which makes substantially one turn so that its tips overlap each other. At this time, a narrow portion16is formed in the region between the portions in which the tip portions of the resistance-adjusting groove15overlap each other.

Next, as shown inFIGS. 3C and 3D, the protective film17which is made of epoxy resin or the like is formed so as to cover the portion of the conductive film13's surface except its portions located at both end portions of the base11. Lastly, as shown inFIGS. 3E and 3F, the plating layer18which is made of a nickel plating layer and a tin plating layer is formed on the surface of the electrode14.

In the above described manufacturing method for the circuit protective element, the impact-absorbing layer12is formed so as to cover both end portions of the insulating base11. Thereafter, the conductive film13is formed so as to cover the surfaces of the base11and the impact-absorbing layer12. Therefore, the impact-absorbing layer12can be formed between both end portions of the base11and the electrode14. Consequently, even if a mechanical impact is applied on both end portions of the base11when the circuit protective element is held, this mechanical impact can be absorbed into the impact-absorbing layer12. Therefore, in order to hold the circuit protective element, even if a chuck100is pressed, by a strong force, on the electrode14located on both end-portion sides of the base11, then the corner portions at both end portions of the base11can be prevented from being chipped. This helps improve its yield rate.

In addition, the impact-absorbing layer12is formed before the conductive film13is formed. Therefore, when the impact-absorbing layer12is formed, the conductive film13which is an element assembly of an electronic component or the portion which fulfills the electrical function of the circuit protective element can be kept from being damaged. This prevents the characteristics of the circuit protective element from getting worse.

Furthermore, after the resist film19is formed on the whole surface other than both end portions of the base11which is made of an insulating mixture of ceramic and glass, the impact-absorbing layer12is formed so as to cover the entire surface of both end portions of the base11. Thereafter, the resist film19is separated from the base11. Therefore, the impact-absorbing layer12can be prevented from going out of the middle portion of the base11, or the portion in which there is no need to provide the impact-absorbing layer12. This makes it possible to form the impact-absorbing layer12precisely at the portion where it needs to be provided.

Herein, in the above described manufacturing method for the circuit protective element, the impact-absorbing layer12is formed only in both end portions of the insulating base11by an electro-less plating method. However, the impact-absorbing layer12may also be formed to cover on the whole surface of the resist film19by a sputtering method and the entire surface of both end portions of the base11. In that case, if the resist film19is removed, the impact-absorbing layer12formed on the resist film19is also removed simultaneously. Therefore, in the same way as the case where the impact-absorbing layer12is selectively formed by means of electro-less plating, the impact-absorbing layer12can be formed only in both end portions of the insulating base11.

INDUSTRIAL APPLICABILITY

As described so far, according to the present invention, an impact-absorbing layer is provided so as to cover at least the corner portions of both end portions of a base which is made of any of ceramic, glass, and a mixture of ceramic and glass, which have an insulation characteristic. In addition, a conductive film is formed so as to cover the surface of this impact-absorbing layer and the surface of the base. In this conductive film, the portion which covers the surface of the impact-absorbing layer is used as an electrode. Therefore, when a resistance value is measured, or when a resistance-adjusting groove is formed, in order to hold an electronic component, even if a chuck is pressed, by a strong force, against the electrode located on both end-portion sides of the base, then the impact-absorbing layer between both end portions of the base and the electrode formed on both end-portion sides of the base by a portion of the conductive film can absorb its mechanical impact. Thereby, the corner portions of both end portions of the base can be prevented from being chipped, thus improving its yield rate.