JP4112417B2 - Chip fuse and manufacturing method thereof - Google Patents

Description

[0001]
[Technical field to which the invention belongs]
The present invention relates to a chip fuse.
[0002]
[Prior art]
Chip fuses used for surface mounting are formed by, for example, a conductive film by thick film printing, a metal film by electroless plating, a metal thin film by sputtering, etc. as a fuse element on an insulating substrate such as a ceramic substrate. .
While such a fuse conductor film is excellent in quick disconnection and ease of manufacture, the pulse resistance performance required as a protective element for an inverter circuit may not be obtained. For this reason, a chip fuse inserted as a protective element in an inverter circuit is required to satisfy not only fast-breaking performance but also pulse resistance.
[0003]
From this point of view, Japanese Patent Application Laid-Open No. 2001-52593 (Patent Document 1) discloses a technique for forming a fuse element on a polyimide resin layer , and this chip fuse is formed on a polyimide resin layer on an insulating substrate. A first metal film is formed on the upper surface with a predetermined fuse pattern, and a second metal film made of a low melting point metal is laminated on the first metal film by plating or the like. The fuse element is composed of the first and second metal films, and the fuse element is covered with an insulating protective layer.
The chip fuse has a complicated manufacturing process and is relatively thick, and the polyimide resin used for the chip fuse has excellent heat resistance, but has the disadvantages that the material is expensive and heat dissipation is low. . Furthermore, since the fuse element is laminated on the polyimide resin layer, the heat generated when the fuse element is energized is stored in the polyimide resin layer without being dissipated to the insulating substrate. There are problems such as excessive rise in the surface temperature of the metal, and unstable insulation after fusing, resulting in variations.
[0004]
Further, in the chip fuse described in Japanese Patent Application Laid-Open No. 11-96886 (Patent Document 2), a film is formed with a resin having low thermal conductivity at approximately the center of the upper surface of the insulating substrate. A fuse element is formed, and an upper surface portion of the lead formed integrally with the fuse element is disposed so as to face both ends of the upper surface of the insulating substrate, and the upper surface portion of the fuse element and the lead is covered with a silicone-based resin film.
In the above-described chip fuse, a resin film having low thermal conductivity is formed in the approximate center on the insulating substrate, and a fuse element is formed thereon, so that the fuse element is not flat and a uniform fuse film cannot be obtained. There are drawbacks. Further, the silicone-based resin film covering the upper surface of the fuse element has poor mechanical strength, and there is a drawback that the fuse blown portion is easily damaged by external stress due to adsorption during mounting.
[0005]
[Patent Document 1]
No. 2001-52593 [Patent Document 2]
Japanese Patent Application Laid-Open No. 11-96886 [0006]
[Problems to be solved by the invention]
The present invention has been made to solve the above-described problems, and the problem is that the manufacturing is easy and the manufacturing cost is reduced, and the required size is reduced while forming the product relatively thin. An object of the present invention is to provide a chip fuse that can ensure mechanical strength, quick disconnection, pulse resistance, and the like.
[0007]
[Means for Solving the Problems]
According to the present invention, a chip fuse in which an adhesive layer is formed on an insulating substrate, a fuse film including a fuse element portion and a surface electrode portion is formed on the adhesive layer, and a protective layer is provided on the fuse element portion. in the adhesive layer has a cutout portion at a substantially central portion, an insulating material having a predetermined heat storage and heat radiation are filled so as to be substantially flat and the adhesive layer in the cutout portion, the fuse film A chip fuse is provided, which is made of a metal foil, and the fuse element portion is disposed on the insulating material.
By configuring the chip fuse as described above, the fuse element portion is not disposed on the adhesive layer that has poor heat resistance and excessive heat storage, and therefore, a heat resistant layer such as a polyimide resin between the fuse film and the insulating substrate. Even if is omitted, a chip fuse having a good pulse resistance can be manufactured by withstanding a heat generation during energization or fusing and providing a fuse element portion made of a metal foil.
[0008]
In the above-mentioned chip fuse, it is preferable to fill the notch portion of the adhesive layer with a silicone resin or an epoxy resin, and by filling them, the fuse element portion of the fuse film is surrounded by the resin, Has the effect of improving the arc-preventing effect and the quick-cutability of fusing. Moreover, with the resin filled in the notch portion of the adhesive layer, suitable heat dissipation and heat storage can be obtained, and excellent fusing characteristics can be obtained. In addition, filling the notch in the adhesive layer with resin flattens the notch and flattened the fuse film so that the fusing characteristics are stable and the chip fuse can be made thinner. Become.
Further, it is preferable that the notch portion of the adhesive layer is filled with a silicone resin or an epoxy resin, and a protective layer covering the fuse film is formed of an epoxy resin having high mechanical strength. The silicone resin or epoxy resin filling the notch ensures an arc extinguishing function and suitable heat dissipation during melting, while mechanical strength and flatness of the outer surface are ensured by a high mechanical strength epoxy resin. As a result, it is possible to obtain the advantages of preventing breakage of the fuse element portion in the mounting process and improving mounting efficiency.
Further, the epoxy resin used in the protective layer, contains silicate as at least a filler, flame resistance, and undercoat having excellent heat resistance and thermal conductivity, contain Alumina at least as a filler, the mechanical strength and heat By adopting a laminated structure with an overcoat having excellent properties, thermal expansion at the time of fusing and external pressure at the time of cutting are absorbed, and mechanical strength and flatness of the outer surface are ensured.
[0009]
【Example】
DESCRIPTION OF EXEMPLARY EMBODIMENTS Hereinafter, preferred embodiments of the invention will be described with reference to the accompanying drawings.
FIG. 1 is a cross-sectional view of a chip fuse 10 of the present invention.
In the chip fuse 10, electrode portions 14a and 14c of a fuse film are provided on an insulating substrate 12 via an adhesive layer 11, and a notch portion 11a is formed in a portion of the adhesive layer 11 where the fuse element portion 14b of the fuse film overlaps. The notch portion 11 a is filled with a resin 13 having predetermined heat resistance and flexibility, and the electrode portions 14 a and 14 c of the fuse film and the fuse element portion 14 b are covered with a protective layer 15. Further, a back electrode 17 is formed on the back surface of the insulating substrate 12, an end face electrode 16 is formed so as to energize the back face electrode 17 and the fuse film electrode portions 14 a and 14 c, and the end face electrode 16 and the back face electrode 17 are further formed. A plating film 18 is formed on the exposed portions of the electrode portions 14a and 14c.
[0010]
Here, an alumina ceramic substrate is used as the insulating substrate 12, but a glass substrate or a resin substrate may be used as long as the insulating property and heat resistance are good.
Moreover, it is preferable to use an epoxy resin sheet as the adhesive layer 11, and in addition, an acrylic resin sheet and a silicone resin sheet can be used. The cutout portion 11a of the adhesive layer 11 preferably has a larger shape than the fuse element portion 14b, and is mainly a circular hole, and can be formed in a rectangular hole, a polygonal hole, or a slit shape in addition to the circular hole.
As the resin 13 filled in the notch portion 11a, a silicone resin or an epoxy resin having flame resistance, excellent heat resistance, and appropriate thermal conductivity is used, and becomes substantially flat with the adhesive layer 11. So as to be filled. When the silicone resin is filled in the notch portion 11a, arc extinguishing performance is high in addition to the above characteristics, so that it can be applied to ratings up to 5A or higher, for example. When the notch 11a is filled with an epoxy resin, it can be applied to ratings up to about 3A, for example, due to the above characteristics.
The fuse film is made of a metal foil having a material and a thickness that meet the desired fusing characteristics, and by etching the metal foil, a required pattern is formed, and the electrode portions 14a and 14c of the fuse film are formed. A fuse element portion 14b is formed. As this metal foil, for example, a copper foil or aluminum foil appropriately selected from a thickness of 5 to 35 μm, and an alloy of copper and another metal can be used. In the case of using copper foil as the fuse film, a tin film is formed on the fuse element portion 14b in order to obtain faster disconnection, and further, in order to prevent diffusion of copper and tin, forming the nickel film may be formed before.
The protective layer 15 is formed by laminating an overcoat 15b on an undercoat 15a, and the undercoat 15a is formed from an epoxy resin containing silicic acid as a filler excellent in flame resistance, heat resistance and thermal conductivity. On the other hand, the overcoat 15b is formed from an epoxy resin containing alumina as at least a filler excellent in mechanical strength and heat resistance. The undercoat 15 a is provided so as to cover the fuse element portion 14 b excluding the electrode portions 14 a and 14 c of the fuse film and the insulating material 13 filled in the cutout portion 11 a of the adhesive layer 11.
The back electrode 17 can be made of a conductive resin or the like, and when formed on the insulating substrate 12 before the fuse film is formed, a metal glaze paste or a metal organic paste can be used. In the case of forming in 12, a conductive resin paste or the like can be used. The end face electrode is formed from a conductive resin paste or a metal film formed by sputtering. Further, the plating film 18 can be formed by tin plating or nickel plating. Further, the effect of lowering the electrode resistance value by using copper plating together. There is also.
[0011]
Next, a method for manufacturing the chip fuse 10 will be described.
FIGS. 2A to 2G are perspective views showing one chip unit for explaining the manufacturing process of the chip fuse of the present invention. Although these steps actually show steps that are developed on a single insulating substrate before being divided into a plurality of chips, they are shown in units of one chip for easy understanding.
First, as shown in FIG. 2B, the adhesive sheet 11 is attached by a laminating method to form an adhesive layer. Here, the insulating substrate 12 is a collective substrate made of alumina ceramic, glass, resin, or the like that is to be cut into a number of unit regions and divided into chips. The adhesive sheet 11 is a sheet made of an epoxy resin, an acrylic resin, a silicone resin, or the like having a large number of unit area areas, and a portion corresponding to a fusing part of the fuse element for each unit area as shown in FIG. A sheet in which a notch 11a is formed is used. The cutout portion 11a of the adhesive sheet 11 is affixed to the insulating substrate 12 with the adhesive sheet 11 having the cutout portion 11a formed in advance. 11a may be formed.
When the adhesive sheet 11 is attached to the insulating substrate 12, the notch 11a is filled with the silicone resin or epoxy resin shown in FIG. 2C by screen printing or potting.
Next, a metal foil made of copper, aluminum, or the like is attached to the adhesive layer 11 by a laminating method, and as shown in FIG. 2D, the fuse film is temporarily fixed, and then thermocompression-bonded. Then, the fuse film is patterned by etching in accordance with a desired fusing characteristic to form the electrode portions 14a and 14c and the fuse element portion 14b as shown in FIG. 2E. At this time, the fuse element portion 14b Is formed within the range of the notch 11 a of the adhesive layer 11. As described above, the fuse element portion 14b may be appropriately subjected to tin plating or nickel plating and tin plating.
Further, after forming the electrode portions 14a and 14c of the fuse film and the fuse element portion 14b, the protective layer 15 including the undercoat 15a and the overcoat 15b that completely covers the fuse element portion 14b is formed. That is, as shown in FIG. 2 (f), first, an epoxy resin containing at least silicic acid as a filler excellent in flame resistance, heat resistance and thermal conductivity is screen printed on the fuse element portion 14b. A coat 15a is formed, and then, as shown in FIG. 2G, an epoxy resin containing at least alumina as a filler excellent in mechanical strength and heat resistance is screen-printed on the undercoat 15a. Thus, the overcoat 15b is formed, and the protective layer 15 is formed by these two layers.
After the formation of the protective layer 15, the back electrode 17 is formed on the back surface of the insulating substrate 12. As described above, the back electrode 17 can be formed by printing and curing a conductive resin. When the back electrode 17 is formed on the insulating substrate 12 before forming the fuse film, printing and baking of a metal glaze paste or a metal organic paste is performed. It can also be formed. Then, after performing the primary division, the end face electrode 16 is formed, and further, the secondary division is performed to form the plating film 18 on the exposed portions of the end face electrode 16, the back electrode 17, and the electrode portions 14a and 14c. The chip fuse 10 is completed.
[0012]
【The invention's effect】
In the present invention, the fuse element portion is not disposed on the adhesive layer that is inferior in heat resistance and excessively stores heat, and is disposed so as to overlap the insulating material filled in the notch portion of the adhesive layer. Therefore, for example, even if a heat-resistant layer such as polyimide resin between the fuse film and the insulating substrate is omitted, a chip fuse that can withstand the heat generated when energized or blown can be manufactured. Therefore, chip fuses of various sizes and various ratings can be provided. In addition, since the fuse film is formed from a metal foil, it is possible to easily form a fuse film with a wide range of fusing characteristics by simply adjusting the thickness of the metal foil according to the desired fusing characteristics, Since it is easy to form a fuse film having a uniform thickness, it is possible to obtain an accurate fusing characteristic.
In addition, by bonding the fuse film to the insulating substrate with an adhesive layer of an epoxy resin sheet, the fuse film can be easily configured on the insulating substrate, eliminating the need for high temperature work, thus simplifying the process. It is.
[0013]
In the present invention, since the resin having predetermined heat resistance and flexibility is filled in the notch portion of the adhesive layer, the fuse element portion is surrounded by the resin, and the arc prevention effect at the time of fusing and the quick fusing property of fusing There is an improvement effect. In addition, due to moderate heat storage and heat dissipation by the resin filled in the notch portion of the adhesive layer, excessive heat storage and heat dissipation can be prevented, and excellent fusing characteristics can be obtained. Furthermore, since the notch of the adhesive layer is filled with resin, the notch becomes flat without being uneven, and the fuse film can be affixed flat, fusing characteristics are stabilized, chip fuse Can be made thinner. If the notch part of the adhesive layer is formed so as to be surrounded by the material constituting the adhesive layer, the resin filled in the notch part is prevented from being released outside the substrate when the fuse film is thermocompression bonded. it can.
[0014]
In the present invention, the arc extinguishing function at the time of fusing is ensured by the silicone resin or the epoxy resin filled in the notch portion of the adhesive layer. In particular, an arc extinguishing function when a high-rated fuse is blown is ensured by the silicone resin.
Further, in the present invention, the fuse element portion is further covered , containing at least silicic acid as a filler , forming an undercoat from an epoxy resin excellent in flame resistance, heat resistance and thermal conductivity, and containing at least alumina as a filler, By forming an overcoat from an epoxy resin with excellent mechanical strength and heat resistance and making them into a laminated structure, it absorbs thermal expansion at the time of fusing and external pressure at the time of interruption, and also has good heat dissipation The mechanical strength and flatness of the outer surface are ensured. Since the undercoat is provided so as to cover substantially the fuse element part excluding the surface electrode part and the insulating material filled in the cutout part of the adhesive layer, the adhesion of the protective layer, the fuse element While ensuring the sealability of the part, excessive heat dissipation to the electrode part through the undercoat is suppressed, and appropriate fusing characteristics can be obtained.
[Brief description of the drawings]
FIG. 1 is a cross-sectional view of a chip fuse of the present invention.
FIGS. 2A to 2F are perspective views showing one chip unit for explaining a manufacturing process of a chip fuse of the present invention.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 10 Chip fuse 11 Adhesion layer 11a Notch part 12 Insulating substrate 13 Notch part filler 14 Fuse film 14b Fuse element part 15 Protective layer 15a Undercoat 15b Overcoat

Claims (6)

In a chip fuse in which an adhesive layer is formed on an insulating substrate, a fuse film including a fuse element part and a surface electrode part is formed on the adhesive layer, and a protective layer is provided on the fuse element part.
The adhesive layer has a notch at a substantially central portion, and the notch is filled with an insulating material having a predetermined heat storage property and heat dissipation property so as to be substantially flat with the adhesive layer. A chip fuse comprising a foil, wherein the fuse element portion is disposed on the insulating material.   The chip fuse according to claim 1, wherein the insulating material is a silicone resin or an epoxy resin.   The chip fuse according to claim 1, wherein the metal foil is a copper foil.   The protective layer is an undercoat provided with an overcoat, and the undercoat is made of an epoxy resin containing at least silicic acid as a filler, and the overcoat is an epoxy type containing at least alumina as a filler. The chip fuse according to any one of claims 1 to 3, wherein the chip fuse is made of resin.   The chip fuse according to claim 4, wherein the undercoat is provided so as to cover substantially the fuse element portion excluding the surface electrode portion and the cutout portion of the adhesive layer.   In a manufacturing method of a chip fuse in which a fuse film is provided on an insulating substrate via an adhesive layer, a step of attaching a sheet-like adhesive layer having a notch formed on the insulating substrate, and an insulating material on the notch Filling the sheet-like adhesive layer and the insulating material with a fuse film, and patterning the fuse film so that a fuse element portion is formed on the insulating material. A method for manufacturing a chip fuse.

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