JP4306892B2 - Method for manufacturing circuit protection element - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a circuit protection element, and more particularly to a chip-type circuit protection element in which a metal-coated fuse element is arranged on a substrate having an outer dimension of about 1 to 2 mm and a method for manufacturing the same.
[0002]
[Prior art]
As a chip-type circuit protection element, for example, a chip-type fuse element 20 as shown in FIG. 3 is known. In this, a fuse element 23 made of a metal film (Cu plating layer) is provided between electrodes 22 provided on both sides of a square plate-like ceramic substrate 21 made of alumina or the like, and this is covered with a glass protective film 24 and an overcoat 25. It is a thing. A narrow portion 23 a is provided at the center of the fuse element 23.
[0003]
In the fuse element 20, when an overcurrent flows, the current concentrates in the narrow portion 23 a of the fuse element 23, and the fuse element 23 is melted by generating heat, so that various electronic devices connected to the fuse element 20 can be connected. It comes to protect.
[0004]
The fuse element 20 is manufactured as follows.
First, for example, a Cr film is formed on the entire surface of a square plate-shaped ceramic substrate of about 10 cm square by sputtering, and a Cu film is formed thereon by sputtering in the same manner. Next, a photosensitive resist is applied, patterning is performed to form an opening, Cu plating is performed according to the opening pattern, and the surface electrode of the electrode 22 and the fuse element 23 are formed by the Cu plating layer. Next, the resist film is peeled off, and further, the Cu film and the Cr film located under the resist film are removed by etching.
[0005]
Next, a glass protective film 24 covering the fuse element 23 is formed by screen printing or the like. Next, the back side electrode of the electrode 22 is formed. Next, after an overcoat 25 made of an epoxy resin or the like is formed on the glass protective film 24, marking is performed. Next, after cutting the ceramic substrate into a series of chips in a strip shape, NiCr films are formed on both end faces of the ceramic substrate by sputtering to form side electrodes of the electrodes 22. Next, after cutting a series of strip-shaped chip groups into individual chips, Ni plating is applied to the electrode 22 whose longitudinal cross-sectional shape is “U” shape, and further, solder plating is applied to form external electrodes.
[0006]
[Problems to be solved by the invention]
However, in such a conventional fuse element 20, since the fuse element 23 is formed by Cu plating, a plating facility for that purpose is required, and more time is required for the plating process. There is a problem that the manufacturing cost is increased.
[0007]
The present invention has been made in view of the above circumstances, and an object thereof is to provide a method of manufacturing a circuit protection element capable of reducing the production cost structure is simple.
[0008]
[Means for Solving the Problems]
In order to achieve the above object, according to the first aspect of the present invention, there is provided a circuit protection element in which electrodes are provided on both sides of a substrate, a fuse element is formed so as to communicate with the electrode, and the fuse element is covered with a protective film. A glass layer is formed on the surface of the metal foil, a substrate is attached to the glass layer, a resist film is then deposited on the surface of the metal foil, and patterning is performed. Form a resist film pattern in the shape of the electrode and the fuse element, and then remove the metal foil in portions other than the lower side of the resist film pattern, then peel off the resist film, and then cover the fuse element The protective film is formed.
[0011]
In the present invention, since the fuse element is formed of a metal foil and the fuse element is formed without the plating process, the equipment and time required for the plating process can be reduced, and the manufacturing cost can be reduced. Further, since the fuse element is formed of a metal foil, it is possible to avoid a defective quality of the fuse element due to a defective plating due to variations in plating conditions, and to improve the product yield. As the metal foil, a conductive foil such as a copper foil is used.
[0012]
Further, when the glass layer is interposed between the fuse element and the substrate, with excellent arc extinguishing properties obtained, the heat radiation at the time of the fuse element blown is reduced fusing characteristics is improved by further metal foil And the substrate are firmly bonded via the glass layer. As the material of the glass layer, low melting point glass such as silicon glass is used.
[0013]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, a circuit protection element according to an embodiment of the present invention will be described with reference to FIG.
The fuse element (circuit protection element) 10 is a fuse element made of copper foil (metal foil) having a thickness of about 5 to 35 μm between both electrodes 12 provided on both sides of a square plate-like ceramic substrate (substrate) 11. 13 is arranged, and this fuse element 13 is covered and protected by a glass protective film (protective film) 14. As the dimensions of the ceramic substrate 11, for example, the size of a normal chip component of about 2 mm × 1.25 mm or 1.6 mm × 0.8 mm is employed. The fuse element 13 is formed in a linear strip shape having a width W of about 20 μm and a length L of about 1.2 mm, and a narrow portion 13a is provided at the center thereof. The surface electrode of the electrode 12 is integrally formed with the fuse element 13 by a copper foil having a thickness of about 5 to 35 μm.
[0014]
A glass layer made of low melting point glass such as silicon glass is deposited on the ceramic substrate 11 to a thickness of about 50 to 100 μm, and the electrode 12 and the fuse element 13 are disposed on the glass layer. The fuse element 13 is covered and protected by a glass protective film 14. Thus, since the fuse element 13 is sandwiched between the glass layers, a preferable arc extinguishing characteristic can be obtained. An overcoat made of an epoxy resin or the like is further coated on the glass protective film 14, but this overcoat need not be provided if the glass protective film has sufficient acid resistance.
[0015]
Next, a method for manufacturing the fuse element 10 will be described with reference to FIG. In this embodiment, for example, a plurality of fuse elements 10 are manufactured simultaneously using a square plate-like ceramic substrate having a side of about 10 cm.
First, a copper foil (metal foil) L having a thickness of about 5 to 35 μm is fixed on a work table by vacuum adsorption, and a low melting point glass such as silicon glass is printed on the surface of the copper foil L by about 50 to 100 μm. Then, the ceramic substrate P made of alumina or the like is pasted while being heated so that bubbles do not enter the glass layer G (see FIG. 1A).
[0016]
Next, after the glass layer G is cured, the copper foil L is cut in accordance with the shape of the ceramic substrate P, and then turned upside down, and then a photosensitive resist is applied to the surface of the copper foil L and patterned. The resist film R is left in the shape of the surface electrode of the electrode 12 and the fuse element 13 to be formed in this manner, and the resist film in other portions is removed (see FIG. 5B).
[0017]
Next, after removing the copper foil L in a portion other than the lower side of the resist film R by etching (see FIG. 4C), the resist film R is peeled off (see FIG. 4D). Thereby, the surface electrode of the electrode 12 and the fuse element 13 are formed of the copper foil L.
[0018]
Next, a glass protective film 14 of low melting point glass such as silicon glass covering the fuse element 13 is formed to a thickness of about 100 to 200 μm by screen printing or the like. Next, the back side electrode of the electrode 22 is formed. Next, after an overcoat made of an epoxy resin or the like is deposited on the glass protective film 14, marking is performed. In addition, when the glass protective film 14 has sufficient acid resistance, formation of overcoat can also be abbreviate | omitted.
[0019]
Next, both end surfaces on the electrode 12 side of the ceramic substrate P are cut by dicing or the like to form a series of chip groups in a strip shape, and a side electrode of the electrode 12 is formed by forming a NiCr film on these end surfaces by sputtering. Next, both end surfaces on the side where the side electrodes are not formed are cut by dicing or the like to form individual chips from a series of strip-shaped chips. Next, Ni plating is applied to the electrode 12 whose longitudinal cross-sectional shape is a “U” shape, and further, solder plating is applied to form an external electrode.
[0020]
Although the chip type circuit protection element has been described in the above embodiment, the present invention can be applied to various circuit protection elements in which a fuse element is arranged on a substrate in addition to the chip type.
[0021]
【The invention's effect】
As described above, according to the present invention, since the fuse element is formed of the metal foil, the equipment and time can be reduced as compared with the case where the fuse element is formed by plating, and the manufacturing cost is reduced. In addition, it is possible to avoid defective quality of the fuse element due to defective plating and to improve the product yield.
[Brief description of the drawings]
FIG. 1 is a plan view showing a circuit protection element according to an embodiment of the present invention.
FIG. 2 is a side view for explaining the method for manufacturing the circuit protection element of the embodiment of the present invention.
FIG. 3 is a plan view showing a conventional circuit protection element.
[Explanation of symbols]
10 Fuse element (circuit protection element)
11 Ceramic substrate (substrate)
12 Electrode 13 Fuse element 13a Narrow part 14 Glass protective film (protective film)
P Ceramic substrate (substrate)
L Copper foil (metal foil)
G Glass layer R Resist film

Claims (1)

An electrode is provided on both sides of a substrate, a fuse element is formed so as to communicate with the electrode, and a circuit protection element in which the fuse element is covered with a protective film is manufactured,
A glass layer is formed on the surface of the metal foil, a substrate is attached to the glass layer, a resist film is then deposited on the surface of the metal foil, and patterning is performed to form a resist in the shape of the electrode and fuse element to be formed. Forming a film pattern, and then removing the metal foil at portions other than the lower side of the resist film pattern, then peeling the resist film, and then forming the protective film covering the fuse element A method for manufacturing a circuit protection element, comprising:

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