JPH07201533A - Chip part - Google Patents

Abstract

PURPOSE:To enable a chip part to be prevented from increasing in leakage current and enhanced in insulating properties by a method wherein a laminate is cut into sticks so as to make inner electrodes exposed at both their end faces, the sticks are burned, coated with epoxy resin except their end faces where the inner electrodes are exposed, and cut into pieces, and both the end faces of each piece are coated with a conductive film. CONSTITUTION:Unburned sheets 4 and inner electrode sheets 3 for a laminated ceramic varistor are laminated together and cut into stick-like pieces so as to make the inner electrodes 3 exposed at both the end faces of each piece where outer electrode films are provided, and the stick-like pieces are burned. Then, each stick-like piece is sealed up or overcoated with epoxy resin, silicone resin, or glass, excluding both its end faces where the inner electrodes are exposed, or unburned sheets 4 and inner electrode sheets 3 are laminated together and cut into stick-like pieces so as not to make a film forming section exposed at both the end faces of each piece, the stick-like pieces are burned, and then, each piece is sealed up or overcoated 5 with epoxy resin, silicone resin, or glass. Both end faces of 8 stick-like piece where the inner electrodes are exposed are coated with an NiCr evaporation film 7, an Ni evaporation film 8, and an Sn/Pb or Au evaporation film 9 to be provided with external electrodes.

Description

[Detailed Description of the Invention] (Paragraphs are numbered for each paragraph.) [0001] The present invention is applied to abnormal high voltage, noise, static electricity, etc. generated in electric equipment and electronic equipment. The present invention relates to a varistor for protecting semiconductors and circuits of equipment. 2. Description of the Related Art In recent electronic devices, elements for the purpose of improving reliability are widely used. Conventionally, an element is laminated and fired so that the internal electrode sheets are alternately exposed on the formed unfired laminated ceramic varistor sheet, and metal paste or the like is applied and baked on both ends where the internal electrodes are exposed. And a method in which a metal paste or the like is applied to both ends of the element, baked, and then plated on the upper layers of both ends. However, metal paste or the like is applied to both ends of the conventional element as described above,
In the method of forming external electrodes after baking or applying a metal paste or the like to both ends of the element, and baking and then plating the upper layer of both ends, the element itself is exposed except for the external electrode surface, so soldering The adverse effect of the flux that sometimes occurs,
For example, the chlorine component causes reduction of the element itself, increase of leakage current, and deterioration of insulation. Further, there occurs a phenomenon that the plating liquid used for plating permeates the element from the electrode material such as metal paste.
It is considered that this is because, when the plating layer is formed, the plating solution penetrates from the electrode material such as the metal paste and destroys the interface between the element body and the metal paste-like electrode material by some reaction. When such a phenomenon occurs, adhesion between the element body and the electrode material in the form of a metal paste is deteriorated or the environment is liable to be adversely affected from the outside.Therefore, in evaluation of environmental characteristics such as long life including humidity resistance. This includes the risk that the quality of electronic devices will not meet the demand for high quality in recent years. In order to solve the above-mentioned drawbacks, the present invention laminates an unfired sheet of a laminated ceramic varistor and an internal electrode sheet so that the internal electrodes are exposed on both end faces. After cutting into sticks and baking, mold or overcoat with epoxy, silicon resin, glass, etc. except for the end faces where the internal electrodes are exposed, or the internal electrodes are exposed at both end faces. So that the internal electrodes are exposed at both ends where the internal electrodes are exposed, after being cut into sticks and fired, and then molded and overcoated with epoxy, silicon resin, glass, etc. A conductive coating is formed by film deposition or the like for surface mounting. [Working] [0006] An unfired sheet of a laminated ceramic varistor and an internal electrode sheet are laminated, cut into sticks so that the internal electrodes are exposed at the end faces, and then fired to remove both end faces where the internal electrodes are exposed. Epoxy, silicone resin, glass, etc. by molding or overcoating with epoxy, silicone resin, glass, etc. For example, after conducting a molding or overcoating with etc., it is cut into individual pieces, and a conductive coating is formed on both ends where the internal electrodes are exposed by coating to form a surface mount. Has the following reasons. (1) Conventionally, compared with the electrode surface where the element itself other than the external electrode surface is exposed, reduction of the element itself and increase of leakage current due to chlorine component in the flux generated during soldering are prevented, It is possible to increase the insulating property. (2) In addition, since the plating process is not performed, there is no concern that the plating solution will penetrate into the element body, and the external electrode can be formed without deteriorating the characteristics of the element. By using the manufacturing method, it is possible to increase the surface mounting density by significantly reducing the thickness of the electrode portion. (3) Further, since the entire element is molded or overcoated with epoxy, silicon resin, glass or the like, it is imprinted on the molded or overcoat. It is possible. FIG. 1 is a laminated structure diagram for explaining the outline of the present invention. In FIG. 2, the one described in FIG. 1 is cut into sticks so that the internal electrodes are exposed at both end faces and then baked, and epoxy, silicon resin, glass, etc. are removed except for the end faces where the internal electrodes are exposed. It is the figure which carried out the mode and the overcoat in. In FIG. 3, the structure described in FIG. 1 is cut into sticks so that the internal electrodes are not exposed at both end faces, and then baked, and a mold or an overcoat made of epoxy, silicon resin, glass or the like is used. FIG. FIG. 4 is a cross-sectional view in which the one described in FIGS. 2 and 3 is further cut into individual pieces, and conductive coatings are formed on both ends where the internal electrodes are exposed by film deposition or the like. 1 is an upper protective sheet, 2 is a lower protective sheet, 3 is an internal electrode sheet, 4 is a ceramic varistor sheet, 5 is a mold or overcoat made of epoxy, silicone resin, glass or the like, 6 is the outer electrode film surface, 7 is NiC
Reference numeral 8 is a vapor deposited film of r or the like, 8 is a vapor deposited film of Ni or the like, and 9 is a vapor deposited film of Sn / Pb or Au. The layers are laminated under the conditions shown in FIG. 1, the internal electrodes 3 are cut into sticks so as to be exposed at the external electrode film deposition portion 6 and then baked, and the external electrode film deposition portion 6 where the internal electrodes 3 are exposed is baked. Excluding epoxy or silicon resin, glass or the like, and an overcoat 5, or the external electrode film forming portion 6
Are cut into sticks so as not to be exposed at both end faces, then baked, and molded with epoxy, silicon resin, glass, etc. or overcoat 5, and then cut into individual pieces to form the internal electrodes. Surface-mounting by depositing a vapor deposition film 7 of NiCr or the like, a vapor deposition film 8 of Ni or the like, a vapor deposition film 9 of Sn / Pb or Au on the external electrode deposition film portion 6 where 3 is exposed to form external electrodes. Turn into. As described above, according to the present embodiment, the reduction of the element itself and the increase of the leakage current due to the chlorine component in the flux generated at the time of soldering are prevented, the insulation property is increased, and the reliability in the surface mounting on the printed board is improved. You can get sex. In addition, since there is no need to go through the plating process, there is no concern that the plating solution will penetrate into the element body, and external electrodes can be formed without deteriorating the characteristics of the element. It is possible to increase the surface mounting density by significantly reducing the thickness of the part. Furthermore, since the entire element is molded or overcoated with epoxy, silicon resin, glass or the like, it is possible to imprint on the molded or overcoat. As described above, according to the present invention, the unfired sheet of the laminated ceramic varistor and the internal electrode sheet are laminated, and the internal electrode is cut into sticks so as to be exposed at both end faces and then fired. , Excluding both end surfaces where the internal electrodes are exposed, mold or overcoat with epoxy, silicon resin, glass or the like, or make a stick so that the internal electrodes are not exposed at both end surfaces. After cutting, bake, epoxy,
After molding or overcoating with silicon resin, glass, etc., it is cut into individual pieces, and a conductive coating film is formed on both ends where the internal electrodes are exposed by coating to form a surface. Implement. By doing so, it is possible to prevent the reduction of the element itself and the increase of the leakage current due to the chlorine component in the flux generated at the time of soldering, to increase the insulation property and to improve the reliability of the surface mounting on the printed circuit board. The effect is obtained. Further, since the plating process is not performed, there is no concern that the plating solution will penetrate into the element body, and the external electrode can be manufactured without deteriorating the characteristics of the element. The effect of significantly reducing the thickness of the electrode portion can be obtained. In addition, since the entire device is molded or overcoated with epoxy, silicon resin, glass or the like, it is possible to stamp on the molded product or overcoat. It is possible to read the product name, etc. and support surface mounting.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a laminated structure diagram for explaining the outline of the present invention. FIG. 2 is a sectional view of the structure described with reference to FIG. 1, cut into sticks so that the internal electrodes are exposed at both end faces, and then baked, and epoxy resin, silicon resin, glass, etc. are removed except for the both end faces where the internal electrodes are exposed. FIG. 3 is a perspective view showing a mold and an overcoat. FIG. 3 is the same as that described with reference to FIG. 1, cut into sticks so that the internal electrodes are not exposed at both end faces, and then baked, and a mold or overcoat made of epoxy, silicon resin, glass or the like is used. FIG. FIG. 4 is a plan view of the structure shown in FIGS. 2 and 3, further cut into individual pieces, and a vapor-deposited film of NiCr or the like, N
It is sectional drawing which deposited the vapor deposition film of i etc. and the vapor deposition film of Sn / Pb or Au in order. [Explanation of reference numerals] 1 upper protective sheet 2 lower protective sheet 3 internal electrode sheet 4 ceramic varistor sheet 5 mold and overcoat with epoxy, silicon resin, glass, etc. 6 external electrode film-coated surface 7 NiCr Vapor deposited film 8 etc. Vapor deposited film 9 Ni etc. Vapor deposited film Sn / Pb or Au etc.

Claims (1)

Claim: What is claimed is: 1. An unfired sheet of a laminated ceramic varistor and an internal electrode sheet are laminated by a method of forming electrodes of a chip varistor body (hereinafter referred to as an element), and the internal electrodes are exposed on both end faces. After cutting it into sticks and firing,
After excluding both end surfaces where the internal electrodes are exposed, a mold or an overcoat with epoxy, silicon resin, glass, etc. is performed, and then the pieces are cut into individual pieces to expose the internal electrodes at both ends. A chip component characterized in that a conductive coating is formed by film deposition and the like to be surface-mounted. 2. An unfired sheet of a laminated ceramic varistor and an internal electrode sheet are laminated by a method of forming an electrode of an element, cut into sticks so that the internal electrodes are not exposed at both end faces, and then fired to obtain epoxy or silicon. A chip component characterized by molding or overcoating with resin, glass, etc., then cutting it into individual pieces, forming a conductive coating with a film, etc., for surface mounting . (1) The items shall be divided into the items (claims) that describe only the items that are essential to the composition of the invention. (2) Change the line for each claim and add a number of 1 (even if the number of claims is 1, it is described as "[Claim 1]". If it is 2 or more, "[ Serial numbers such as "Claim 1]" and "[Claim 2]".)