JPH046198Y2 - - Google Patents

Description

[Detailed description of the invention] [Field of industrial application] The present invention relates to a cylindrical chip capacitor having metal caps serving as external electrodes at both ends of a cylindrical metallized film capacitor element. By connecting with conductive adhesive,
The present invention relates to a cylindrical chip capacitor that can be easily manufactured at low cost and has high reliability when mounted on a circuit board using the dip-flow method.

[Prior Art] Conventionally, when a cylindrical metallized film capacitor element having a winding hole is used as a chip mount type capacitor, as shown in FIG. A cylindrical chip capacitor 11 is formed by thermally spraying a conductive material such as solder (hereinafter referred to as metallicon) to form the external electrode 4.

In this capacitor element 2, a trace remains as the winding hole 2a after the winding core is removed, and if left as is, there is a risk that the conductive material due to the metallicon treatment will penetrate deep into the winding hole 2a and cause a short circuit. This is prevented by putting a filling 8 such as a plastic rod in 2a.

[Problem to be solved by the invention] In the case of the conventional cylindrical chip capacitor having the above-mentioned configuration, when mounting the board by the solder dip flow method, the electrodes formed with the metallicon are exposed to the high temperature of the solder bath. If it comes into direct contact with molten solder, it will soften or melt.
In extreme cases, the electrical connection of the metal contact portion may become open.

In addition, the external electrode formed using metallicon technology has a weak connection with the capacitor element, so
There is a risk that it will peel off due to impact or the like, damaging the connection between the electrode and the element. Furthermore, electrodes made of metallicon have the problem that the metal particles have a coarse density, allowing moisture to enter the capacitor element through the particles, reducing the moisture resistance of the element. This is the cause of a significant decline.

Therefore, in order to solve these problems, conventional cylindrical chip capacitors include external electrodes formed only by the metallization technology as described above.
A method has also been proposed in which an external electrode is formed by further covering the metallicon electrode with a metal cap and mechanically and electrically connecting the metal cap and the metallicon electrode using techniques such as welding or thermal welding.

However, even in this case, the effective area of the connection between the metallicon electrode and the metal cap is not very large, and the adhesive strength itself between the metallicon electrode and the capacitor element is not very large, so these techniques Electrodes formed by combining these are also by no means sufficient in terms of mechanical and electrical connection characteristics.

Further, in the above-mentioned cylindrical chip capacitor, it is necessary to fill the winding hole with metallicon to prevent conductive material from entering, so extra members and extra assembly steps are required.

The present invention was devised in view of the above-mentioned problems, and even when applied to board mounting using the solder dip flow method, it can ensure sufficient electrical connection and mechanical adhesive strength, and is moisture resistant. The object of the present invention is to provide a cylindrical chip capacitor that is of good quality, has no risk of deterioration in reliability, and can be manufactured easily at low cost.

[Means for Solving the Problems] In order to achieve the above-mentioned object, the cylindrical chip capacitor of the present invention has a cylindrical metallized film capacitor element having a winding hole, and a cylindrical metallized film capacitor element having a winding hole at both ends facing the winding hole of the capacitor element. The part is provided with a protrusion to be inserted into the winding hole, and the part other than the part facing the capacitor element winding hole is covered with a metal cap with a through hole and bonded with a heat-resistant conductive adhesive,
A heat-resistant conductive adhesive is applied to the end face portion of the capacitor element exposed through the through-hole and a portion around the through-hole of the metal cap, and a plating layer is further formed on the adhesive and the metal cap. It is something.

[Function] The cylindrical chip capacitor of the present invention has great heat resistance by connecting metal caps with a heat-resistant conductive adhesive to form external electrodes, and the external electrodes do not soften or melt due to the heat of soldering. In addition, by applying a heat-resistant conductive adhesive around the through hole formed in the metal cap, the adhesive area between the capacitor element and the metal cap increases, and the metal cap Since the metal cap is firmly connected by being sandwiched between the metal caps, there is no risk of the metal cap peeling off due to impact or the like.

Furthermore, since the end face of the capacitor element is completely covered by the metal cap and the adhesive having a higher particle density than metallicon, moisture does not enter the inside of the element.

Furthermore, by providing a protrusion that is inserted into the winding hole on the part of the metal cap that faces the capacitor element winding hole, there is no need to thermally spray a conductive material to form external electrodes, making it easier to wind the capacitor element. Even if the core hole is not filled with a plastic rod or the like, there is almost no possibility that the conductive substance will penetrate deep into the winding hole.

[Example] Hereinafter, an example of the present invention will be described based on the drawings.

1 to 4 show one embodiment of the present invention. FIG. 1 is a perspective view of a capacitor element constituting a cylindrical chip capacitor, FIG. 2 is a schematic perspective view of a cylindrical chip capacitor, and FIG. Figure 3 is a cross-sectional view of a cylindrical chip capacitor, Figure 4 shows a metal cap in a cylindrical chip capacitor, and Figure 4A
is a perspective view, and FIG. 4B is a sectional view.

In the figure, a cylindrical chip capacitor 1 is constructed by stacking and winding a metallized film in which a metal for internal electrodes such as aluminum is vapor-deposited on the surface of a dielectric film made of synthetic resin such as polyester, and then heat-treating the film. Cylindrical metallized film capacitor element 2
is formed. Then, the capacitor element 2
A metal cap 3 is placed on both ends of the cap 3 and connected with a heat resistant conductive adhesive 5 to form an external electrode 4. Incidentally, 2a is a winding hole formed at the site where the winding core is removed.

The metal cap 3 is formed by punching a metal plate using a press, forming a tapered protrusion 3b to be inserted into the winding hole 2a in a portion facing the winding hole 2a of the capacitor element 2, and forming a tapered protrusion 3b to be inserted into the winding hole 2a. A plurality of through holes 3a are provided in a portion of the element 2 other than the portion facing the winding hole 2a, and the element 2 is formed into a cap shape, and its surface is plated with tin, solder, etc. to improve solderability.

In addition, the heat-resistant conductive adhesive 5 is made of a heat-resistant synthetic adhesive such as epoxy or polyimide as a base, and mixed with metal particles mainly composed of silver, which has good conductivity. There is.

When the metal cap 3 is disposed on the end surface of the capacitor element 2, forming the protrusion 3a on the metal cap 3 facilitates positioning of the metal cap 3 with respect to the capacitor element 2, and also allows the winding hole to This completely prevents the heat-resistant conductive adhesive 5 from entering.

In addition, when connecting the metal cap 3 to the end face portion of the capacitor element 2, not only the heat-resistant conductive adhesive 5 is applied to the back surface of the metal cap 3, but also the portion exposed from the metal cap through hole 3a of the capacitor element 2 is applied. By applying a heat-resistant conductive adhesive 5 to the area around the through hole 3a of the metal cap 3, the adhesive area is increased and the metal cap 3 is sandwiched between the adhesive 5 and firmly connected.

Further, a heat-resistant conductive adhesive 5 and a metal cap 3
By covering the metal cap with a plating layer 6 to form the external electrode 4, a decrease in heat resistance and moisture resistance due to the provision of the through hole 3a in the metal cap 3 is prevented.

The plating layer 6 includes a first layer 6a formed directly on the heat-resistant conductive adhesive 5 and the metal cap 3, and a second layer 6b formed on the first layer 6a.
It has a two-layer structure. The first layer 6a
The second layer 6b is made of nickel or copper from the viewpoint of prevention of silver corrosion due to soldering and connection strength with the conductive adhesive 5, and the metal constituting the second layer 6b is made of tin or solder which has good compatibility with solder. has been selected.

In this way, a cylindrical chip capacitor formed with an external electrode having a metal cap is shown in FIG. Alternatively, the exterior 7 may be formed of epoxy resin or the like.

[Effects of the invention] As detailed above, the cylindrical chip capacitor of the invention has great heat resistance by connecting the metal caps with a heat-resistant conductive adhesive to form the external electrodes, and is able to achieve high heat resistance during soldering. This prevents the external electrode from softening or melting, and by applying a heat-resistant conductive adhesive around the hole formed in the metal cap, the bonding area between the capacitor element and the metal cap is increased. At the same time, since the metal caps are firmly connected by being sandwiched between the adhesives, excellent connection strength can be obtained in that there is no risk of the metal caps peeling off due to impact or the like.

In addition, the end face of the capacitor element is completely covered by the metal cap and the adhesive, which has a higher particle density than metallization, and by forming a plating layer on the adhesive and the metal cap, moisture can enter the inside of the capacitor element. High reliability can be obtained.

Furthermore, by providing a protrusion that is inserted into the winding hole in the part of the metal cap that faces the capacitor element winding hole, there is no need to thermally spray a conductive material to form the external electrode, so the capacitor element Even if the winding hole is not filled with a plastic rod or other material, there is almost no risk of the conductive substance penetrating deep into the winding hole, so there is no need for special materials or processes to block the winding hole. It is easy to manufacture and can be provided at low cost.

[Brief explanation of the drawing]

FIG. 1 is a perspective view of a capacitor element in a cylindrical chip capacitor of the present invention, FIG. 2 is a schematic perspective view of a cylindrical chip capacitor of the present invention, and FIG. 3 is a sectional view of a cylindrical chip capacitor of the present invention. 4
The figures show the metal cap of the cylindrical chip capacitor of the present invention, FIG. 4A is a perspective view, and FIG. 4B is a perspective view.
is a sectional view, and FIG. 5 is a sectional view of a conventional cylindrical chip capacitor. DESCRIPTION OF SYMBOLS 1... Cylindrical chip capacitor, 2... Cylindrical metallized film capacitor element, 2a... Winding hole, 3... Metal cap, 3a... Through hole, 3b...
... Protrusion, 4 ... External electrode, 5 ... Heat-resistant conductive adhesive, 6 ... Plating layer, 6a ... First layer, 6b
...Second layer.

Claims (1)

[Scope of Claim for Utility Model Registration] (1) At both ends of a cylindrical metallized film capacitor element having a winding hole, protrusions to be inserted into the winding hole are provided at the portions facing the winding hole of the capacitor element. In addition, a metal cap with a through hole is placed over the portion other than the portion facing the capacitor element winding hole and bonded with a heat-resistant conductive adhesive, and the end face portion of the capacitor element exposed through the through hole and the through hole of the metal cap are covered. A cylindrical chip capacitor characterized in that a heat-resistant conductive adhesive is applied around the hole, and a plating layer is further formed on the adhesive and the metal cap. (2) The conductive component of the conductive adhesive is mainly silver, and the plating layer is formed on the adhesive and a first layer made of nickel or copper formed on the metal cap, and on the first layer. A cylindrical chip capacitor according to claim 1, characterized in that the second layer is made of tin or solder.