JPH10261545A - Chip-like electronic component - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prevent the contamination, poor soldering, cracking, dropping, and damage by coating outer electrodes with a thermally sublimative or meltable thin film. SOLUTION: This electronic component body has many inner electrodes laminated and connected to end electrodes 10 in a dielectric 11. The electrode 10 has a Ni plated lower layer and Sn or solder plated upper layer to avoid producing fine powder (oxides etc.) of Sn or solder because of the exposed end electrodes 20. An inorg. or org. thin film 30 is formed to cover at least the surface of the electrodes 20.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a surface-mounted chip component of an electronic component, that is, a chip-shaped electronic component such as a chip capacitor and a chip resistor.

[0002]

2. Description of the Related Art FIG. 3 shows an example of a chip capacitor as a general chip-shaped electronic component, which has a structure in which a large number of internal electrodes are laminated inside a dielectric 11 and connected to an end electrode 20. The end electrode 20 has, for example, a nickel (N
i) The upper layer is tin (Sn) or solder plated.

FIG. 4 shows an example of a chip resistor. A RuO ₂ -based resistive film is formed on an insulating substrate 13 such as alumina, and end electrodes 20 connected to both ends of the resistive film are connected to both ends of the insulating substrate 13. And a protective coating 14 made of glass or resin for protecting the resistive film.

In general, the above-mentioned chip-shaped electronic component is mounted on a surface-mounted printed board by an electronic component mounting machine by a bulk feeder system, a tape carrier system, a disk pack system, or the like.

FIG. 5 shows an example of a bulk feeder proposed in Japanese Patent Application Laid-Open No. 7-176893, etc., in which a large number of chip-like electronic components 10 are stored in a bulk in a plastic case 2 of a hopper unit 1. The chip-like electronic component 10 is supplied to a predetermined component supply position P through a supply pipe 3 inserted into the bottom of the hopper unit and a chute 4 communicating with the supply pipe 3. At this time, the hopper unit 1 is vibrated up and down so that the chip-shaped electronic components 10 are smoothly dropped and supplied.

FIGS. 6 and 7 show another example of a bulk feeder, which is called a ball feeder. In this case, a vibration is always applied to the part ball 5 by the vibration generating unit at the lower part of the device, and a mechanism for aligning and supplying the chip-shaped electronic components 10 along the spiral component supply groove 6 on the inner surface of the part ball 5 is provided. Has become.

A chip capacitor, a chip resistor and the like as chip-like electronic components which are put into a bulk feeder in a bulk state as described above have end electrodes as external electrodes on the outer surface of the electronic component body. The lower layer of the unit electrode is, for example, nickel (Ni), and the upper layer is tin (Sn) or solder plated. Therefore, the chip-shaped electronic component is put into the bulk feeder in a state where the tin or solder plating surface of the end electrode is exposed, and no special treatment has been performed particularly for the bulk feeder.

[0008]

However, when chip-type electronic components such as conventional chip capacitors and chip resistors are mounted on a printed circuit board by an electronic component mounting machine in a bulk feeder system for a long time, the following problems occur. Occurs.

(1) In each of the bulk feeder shown in FIG. 5 and the ball feeders shown in FIGS. 6 and 7, the supply operation is performed by applying vibration to the chip-shaped electronic component.
The chip-shaped electronic components 10 in the plastic case 2 or the parts balls 5 collide with each other and rub against each other, so that fine powder (oxide or the like) of tin or solder on the end electrode surface adheres to the entire internal chip-shaped electronic components, Black stains occur.

(2) When the chip-shaped electronic component to which the fine powder is attached is soldered to a printed circuit board by solder reflow (including solder flow), the adhesion of the fine powder deteriorates the solder wettability of the end electrodes. , Which often causes poor soldering.

(3) The chip-shaped electronic components collide with each other and rub against each other for a long time, so that cracks, chips or scratches are generated.

[0012] In view of the above, the present invention, at least, coats at least the external electrode with a thin film which is sublimable or meltable by heating, thereby preventing generation of dirt, prevention of poor soldering, cracking and chipping. It is another object of the present invention to provide a chip-shaped electronic component capable of preventing occurrence of scratches.

Other objects and novel features of the present invention will be clarified in embodiments described later.

[0014]

In order to achieve the above object, the present invention relates to a chip-shaped electronic component having an external electrode on the outer surface of an electronic component main body, wherein at least the external electrode surface is heated or sublimated or melted. It is characterized by being covered with a thin film of.

It is preferable that the film sublimates or melts at a solder melting temperature or lower.

Further, it is preferable that the film is made of a material that is not tacky and is not brittle.

[0017]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Embodiments of a chip-shaped electronic component according to the present invention will be described below with reference to the drawings.

FIG. 1 shows a first embodiment of a chip-shaped electronic component according to the present invention, which is applied to a chip capacitor. In this figure, when the chip capacitor is of a multilayer type, the electronic component body has a structure in which a large number of internal electrodes are laminated inside the dielectric material 11 and connected to the end electrodes 20. Nickel (Ni), and the upper layer is tin (Sn) or solder plated.
Then, when put into the bulk feeder, the generation of fine powder (oxide or the like) such as tin or solder due to exposure of the end electrodes 20 as external electrodes at both ends of the surface of the electronic component body is prevented. For this purpose, a thin film 30 of an inorganic or organic material is formed so as to cover at least the surface of the end electrode 20. However, since it takes time and labor to form the film 30 selectively on the end electrode 20, it is preferable to provide the film 30 on the entire surface of the electronic component body. It is possible to prevent cracking, chipping and flaws not only in the 20 portions but also in the dielectric 11 portions.

The film 30 can be formed by surface treatment by a wet method (dip, dipping, etc.) or a dry method (powder melting, PVD, CVD, etc.) of an inorganic or organic material. It is about 0.1 μ to about 100 μ.

The material of the film 30 is a fluorine resin, a silicon resin, a urethane resin, an antioxidant, a parylene resin, etc., and has a property that does not affect the characteristics as a chip capacitor, and has at least an insulating property. Things.

The film 30 can be supplied to a bulk feeder in the same manner as a conventional chip-shaped electronic component, and is maintained in a solidified state at normal temperature so as to be easily handled and handled. It is a material that does not generate fine powder or the like even when rubbed, that is, a material that has no tackiness (stickiness) and is not brittle.

Further, the film 30 is sublimated or melted at the time of soldering the end electrode 20 to the printed circuit board so as not to hinder the soldering process by solder reflow or the like. Specifically, the coating 30 is
It has the property of sublimating or melting below the solder melting temperature.

According to the first embodiment, the following effects can be obtained.

(1) It is applicable to various supply systems including the bulk feeder shown in FIG. 5 and the ball feeders shown in FIGS. 6 and 7, and has a thin film 30 made of a material having no tackiness (stickiness) and being not brittle. Since it is formed to have an appropriate thickness so as to cover the surface of the unit electrode 20, there is no dirt on the chip capacitor surface even when it is housed in the feeder for a long time, and the generation of cracks, chips and scratches is prevented. Can be achieved. In particular, when components are mounted for a long time by the bulk feeder method, it is necessary to reduce the amount of input in the case to tens of thousands. In this case, it is possible to eliminate the problem.

(2) Fine powders such as oxides are prevented from adhering to the end electrodes 20, so that solder wettability is improved and soldering is performed when soldering is performed on a printed circuit board by solder reflow (including solder flow). The occurrence of defects is eliminated. At the soldering temperature, the thin film 30 sublimates or melts and disappears from the surface of the end electrode 20.
The coating 30 itself does not prevent soldering.

(3) Even when the chip capacitor is stored for a long period of time, since the end electrode 20 is covered with the film 30, the tin or solder plating surface of the end electrode 20 is not oxidized. Thus, oxidation of the end electrode 20 can be prevented for a long period of time.

FIG. 2 shows a second embodiment of the chip-shaped electronic component according to the present invention, which is applied to a chip resistor. In this figure, a chip resistor is formed by forming a resistive film 15 of RuO ₂ or the like on an insulating substrate 13 of alumina or the like, and connecting end electrodes 20 connected to both ends of the resistive film 15 to the insulating substrate 1.
3, glass for protection of the resistive film,
The electronic component body is provided with a resin-based protective coat 14. Then, a thin film 30 of an inorganic or organic material is formed so as to cover at least the surface of the end electrode 20 of the electronic component body. However, the end electrode 20
Since it takes time and labor to form the film 30 selectively on the part, it is preferable to provide the film 30 on the entire surface of the electronic component main body.
The occurrence of cracks, chips, and scratches in the insulating substrate 13 as well as the zero portion can be prevented.

The method of forming the coating 30 by the surface treatment, the material, and the like are the same as those in the first embodiment.

In each of the above embodiments, the case of a chip capacitor and a chip resistor has been described as an example of a chip-shaped electronic component. The present invention can be applied, and the external shape of the chip-shaped electronic component is not limited to the rectangular parallelepiped shape, but can be applied to a cylindrical shape or the like.

Although the embodiments of the present invention have been described above, it is obvious to those skilled in the art that the present invention is not limited to the embodiments and various modifications and changes can be made within the scope of the claims. There will be.

[0031]

As described above, according to the chip-shaped electronic component of the present invention, at least the surface of the external electrode formed on the outer surface of the electronic component body is covered with a thin film capable of being heated and sublimated or melted. With this configuration, it is possible to prevent the occurrence of dirt on the component surface, the occurrence of cracks, chips, and scratches, and the prevention of soldering defects caused by the attachment of fine powder such as oxides. In this case, the external electrodes can be prevented from being oxidized.

[Brief description of the drawings]

FIG. 1 is an enlarged sectional view of a first embodiment of a chip-shaped electronic component according to the present invention, which is applied to a chip capacitor.

FIG. 2 is an enlarged sectional view of a second embodiment of the chip-shaped electronic component according to the present invention, which is applied to a chip resistor.

FIG. 3 is a perspective view showing a conventional chip capacitor.

FIG. 4 is a perspective view showing a conventional chip resistor.

FIG. 5 is a sectional view showing an example of a bulk feeder.

FIG. 6 is a front view, partially in section, showing an example of a ball feeder.

FIG. 7 is a plan view of the same.

[Description of Signs] 1 Hopper unit 2 Plastic case 3 Supply pipe 5 Parts ball 6 Parts supply groove 10 Chip-shaped electronic component 11 Dielectric 13 Insulating substrate 14 Protective coat 15 Resistive film 20 End electrode 30 Film

Claims (3)

[Claims] 1. A chip-shaped electronic component having an external electrode on an outer surface of an electronic component main body, wherein at least the surface of the external electrode is covered with a thin film capable of being heated and sublimated or melted by heating. 2. The chip-like electronic component according to claim 1, wherein said coating sublimates or melts at a temperature lower than a solder melting temperature. 3. The chip-shaped electronic component according to claim 1, wherein the film is made of a material that is not sticky and is not brittle.