JPH0581162B2 - - Google Patents

Description

[Detailed description of the invention]

[Industrial Field of Application] The present invention relates to a chip-type film capacitor used for surf ace mounts, etc., which require miniaturization and heat resistance. [Prior Art] A film capacitor uses a plastic spread in the form of a film as a dielectric, and electrodes are formed on both sides of the dielectric film by metallization, etc., and the capacitor element is formed by winding or layering. It is obtained by electrically connecting the electrode to an external electrode by metallization treatment or the like, and then applying an exterior means such as a resin exterior. In recent years, electronic components are mounted by placing the electronic components at predetermined positions on a printed wiring board and soldering them using a method such as a reflow solder method, a wave solder method, or a dip solder method. In any case, when electronic components are soldered to a printed wiring board, they are exposed to high temperatures of about 230 to 260° C. for several seconds to tens of seconds.
For this reason, chip-type electronic components are required to have heat resistance. Further, in order to miniaturize electronic devices, higher packaging density of electronic components is required, and the need to mount a large number of electronic components on a printed wiring board requires miniaturization of electronic components as well. Resin films such as polyethylene, polystyrene, polycarbonate, polyethylene terephthalate, and polyphenylene sulfide have conventionally been used as dielectrics for film capacitors. However, such conventional materials have melting points that are comparable to or lower than the melting temperature of solder.
Films such as polyethylene terephthalate and polyphenylene sulfide have relatively high melting points and are said to be suitable for heat-resistant applications. However, in reality, the film begins to soften before it reaches its melting point, so even if measures such as making the exterior material sufficiently thick to prevent heat conduction are taken, the permissible temperature is only 150°C at most. However, it was difficult to use it for Surf Ace mounts under the same conditions as other electronic components. Therefore, recently, polyimide resin films, which have a high melting point and are heat resistant, are being considered. This resin is suitable as a dielectric material due to its high melting point and heat resistance, but it is difficult to process due to the material's low dielectric constant and mechanical properties, so it cannot be processed into a thin film. This was difficult and had the disadvantage that it was difficult to miniaturize the capacitor. [Problems to be Solved by the Invention] The present invention improves these drawbacks of conventional film capacitors, and aims to provide a chip-type film capacitor that can be miniaturized and has heat resistance. [Means for Solving the Problems] The chip-type film capacitor of the present invention uses a polyketone sulfide film that has heat resistance and can be miniaturized as a dielectric material, and electrodes are formed on both sides of this polyketone sulfide film. are wound or layered to form a capacitor element, and are equipped with a means for electrically connecting the electrodes of this capacitor element and external terminals for the Surf Ace mount, and are further provided with an exterior casing as necessary. It is a method that has been applied. [Function] The polyketone sulfide used in this invention is

〔Example〕

Hereinafter, the chip-type film capacitor of the present invention will be explained in detail according to examples. Figure 1 shows a typical capacitor element 1 of this invention.
FIG. 3 is an exploded perspective view showing the structure. In the figure,
An electrode 4 is formed on one surface of a strip-shaped polyketone sulfide film 2 by metallizing a metal such as zinc or aluminum, leaving a strip-shaped untreated portion 3 at one end. Then, the capacitor element 1 is formed by overlapping and winding the two strip-shaped films 2 that have undergone these treatments so that the untreated portions 3 are located in opposite directions. At this time, the electrodes 4 formed on the two strip-shaped films 2 by metallization are exposed at both winding end faces of the capacitor element 1. FIG. 2 is a cross-sectional view showing the exterior state of the chip-type film capacitor of the present invention that houses the capacitor element 1, and the electrodes 4 exposed on the winding end faces on both sides of the capacitor element 1 are treated with metallized or conductive. It is connected to one end of a plate-shaped external terminal 6 that can be mounted on the surface of the surface by an electrical connection means 5 such as an adhesive. Parts of the capacitor element 1, the electrical connection means 5, and the external terminals 6 are covered with an exterior 7 made of an exterior material such as a heat-resistant thermosetting resin. Note that the external terminal 6 protruding from the side surface of the exterior 7 is bent into a substantially U-shape from the side surface to the bottom of the exterior 7, so that it can be surface mounted when placed on a printed wiring board. ing. In this example, a capacitor element was formed by overlapping and winding dielectric films on which metal electrodes were formed by metallization, but the capacitor of the present invention is not limited to this structure. Alternatively, they may be stacked in a laminated manner instead of being rolled. Further, the electrode may be formed by overlapping a dielectric film and a foil-like metal electrode to form a capacitor element. Regarding the connection between the capacitor element and the external electrode, it is also possible to draw out the lead from the electrode part and connect it to the external terminal by means such as welding, without using metallicon treatment or conductive resin. It goes without saying that the shape of the external terminal and the packaging method are not limited to those of this embodiment as long as they are suitable for the purpose of the Surf Ace mount. In particular, since the heat distortion temperature of polyketone sulfide is higher than the melting solder temperature, the outer sheath 7 for heat resistance is not necessarily required. Next, we will show an experimental example in which capacitors were created by forming electrodes on the film surface and their characteristics were compared. (Example of the Present Invention) First, as an example of the present invention, a polyketone sulfide film with a thickness of 2 μm was used as a dielectric, and aluminum layers with a thickness of about 10 Å were vacuum-deposited as electrodes on both sides of this film. This electrode area has an area of 2 cm x 2 cm, or 4 cm ² . Then, a metal lead was electrically connected to the surface of the vapor-deposited electrode using a conductive adhesive to complete a capacitor on a flat plate. (Comparative Example) As Comparative Example 1, a capacitor was created using a polyethylene terephthalate film as a dielectric film. A polyethylene terephthalate film having a thickness of 2 μm was used as in the example of the present invention. All other structures and manufacturing methods were made under the same conditions as the examples of the present invention. Further, as Comparative Example 2, a capacitor using a polyphenylene sulfide film was created. The same 2 μm polyphenylene sulfide film as in the above example was used, and the other structures and manufacturing methods were all the same as in the examples of the present invention. Then, the relative permittivity was determined by actually measuring the capacitance value and capacitance of these capacitors. The results are shown in the table below.

〔Effect of the invention〕

As described above, the chip-type film capacitor of the present invention has the following features: (1) The relative dielectric constant of the polyketone sulfide film is higher than that of other heat-resistant resin films, and therefore a large capacitance per unit volume can be obtained. ,
Capacitors can be made smaller. (2) Polyketone sulfide film has excellent mechanical properties such as tensile strength, so even if the film thickness is made extremely thin, it can be processed into capacitor elements, making it possible to manufacture small and large-capacity capacitor elements. be. (3) Since the tensile strength is high and tension can be applied to the film, when winding the film with tension applied to it, as in the case of wound-wound capacitor elements, the element is firm and can be wound stably. Vibration is prevented and electrical characteristics are stabilized. Furthermore, there is no inconvenience such as cutting the film during winding work, and productivity is improved. (4) Since polyketone sulfide film has a high temperature resistance, the dielectric film does not deteriorate even when exposed to the high temperature of molten solder when soldering to a printed wiring board. It has the following effects and is suitable for chip-type film capacitors that are required to be compact and have heat resistance characteristics.

[Brief explanation of drawings]

FIG. 1 is an exploded perspective view showing the element structure of a chip-type film capacitor according to the present invention. FIG. 2 is a sectional view showing a completed chip-type film capacitor of the present invention using the capacitor element of FIG. 1. DESCRIPTION OF SYMBOLS 1... Capacitor element, 2... Polyketone sulfide film, 3... Untreated portion, 4... Electrode, 5... Electrical connection means, 6... External terminal, 7
...Exterior.

Claims (1)

[Claims] 1 A capacitor element formed by using a polyketone sulfide film as a dielectric layer, electrodes arranged on both sides of the polyketone sulfide film, and formed by winding or stacking them in layers, an external terminal for SurfAce mount, and this capacitor element. A chip-type film capacitor characterized by comprising means for electrically connecting the electrode and an external terminal for a Surf Ace mount.