JPH04255627A - Manufacture of chip-type fuse - Google Patents

Abstract

PURPOSE:To provide a chip-type fuse with excellent contact strength of its electrode part, excellent uniformity in characteristics and instant break property after the meltable body is melted, and excellent in mass production. CONSTITUTION:The surface of a ceramic base 2 is processed to have a roughness of 2-6mumRmax, thereafter, a metallic (copper) coat 6 is formed on the surface of the substrate 2, then, a resist film 10 is formed on the metallic coat 6, then, exposure, development, etching, separation of resist film 10 are performed, only the necessary part of the metallic coat 6 is left to form a conductor circuit 3 and an electrode 4, then, a protective film 9 is formed on the upper surface of the conductor circuit 3 and the upper exposed surface of the ceramic substrate 2 and thereafter to be formed in a chip shape.

Description

[Detailed description of the invention]

0001

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for manufacturing a chip type fuse.

0002

[Background Art] Conventionally, a metal fusible material was connected between the terminals of a glass tube in order to prevent accidents such as overheating of electronic equipment and fire due to overcurrent caused by failures such as malfunctions and short circuits in electronic equipment. There was a tube fuse. However, as electronic devices have become smaller, problems have arisen with the tubular fuses, such as being too large, poor in mass production, and difficult to surface mount on wiring boards. To solve this problem, a chip-type fuse was proposed that is easy to miniaturize, has excellent mass production, and is easy to surface-mount on wiring boards. These chip type fuses are formed on a ceramic substrate in consideration of the heat generated when the fuse is cut. Generally, an alumina ceramic substrate is used as the ceramic substrate, and electrodes and a fusible material are generally formed on the upper surface of the alumina ceramic substrate by a thick film method, a plating method, or the like.

0003

However, when forming a fusible body by the thick film method, the surface roughness of the part (ceramic substrate) on which the fusible body is formed is 0.2 to 2.0 μmRma.
If it is less than There are disadvantages such as high

On the other hand, when forming a fusible body by a plating method, it is necessary to roughen the ceramic substrate before plating, and the surface roughness of the part where the fusible body is to be formed is, for example, 1 to 2 μm.
If it is less than Rmax, the fusible material will remain in place after melting and the fast cutting performance will be reduced, and if it is more than 8μmRmax, the adhesion strength between the fusible material and the electrode part will be weak, and the width of the fusible material will be reduced due to the large surface roughness. This results in drawbacks such as the fact that the thickness and resistance of the fuse are not constant, and the resistance value of the fuse is not constant.

The present invention eliminates these drawbacks and provides a method for manufacturing a chip-type fuse that has excellent adhesion strength in the electrode portion, excellent fast-acting properties and uniformity of characteristics after the fusible material is melted, and is excellent in mass production. It is something to do.

[0006]

[Means for Solving the Problems] The present invention has a surface roughness of 2.
After roughening the surface of the ceramic substrate so that Rmax is ~6 μm, a metal coating is formed on the surface of the ceramic substrate, and then a resist film is formed on the top surface of the metal coating,
After that, the resist film is removed by exposure, development, and etching, leaving only the necessary parts of the metal coating to form a conductor circuit and electrodes. After forming a protective film on the upper surface of the conductor circuit and the upper exposed surface of the ceramic substrate, This invention relates to a method for manufacturing a chip-type fuse that is molded into a chip.

The ceramic substrate used in the present invention is not particularly limited, but it is preferable to use an alumina substrate. There are no particular restrictions on the method of roughening the surface of the ceramic substrate, but it is preferable to use an alkali molten salt (roughening liquid) such as NaOH or KOH to roughen the surface. Then, the surface roughness of the ceramic substrate will be 2.0.
~6.0 μm Rmax. In the present invention, the surface roughness after roughening is 2 to 6 μm Rma
x, and if it exceeds 6μm Rmax, the thickness and width accuracy of the fusible part (conductor circuit part) formed by forming a metal film and pattern etching will decrease, and the resistance value as a fuse will remain constant. I won't. Furthermore, if the surface roughness of the substrate is less than 2 μm Rmax, it becomes difficult for the fusible metal to move after melting, resulting in a decrease in fast cutting performance.

[0008] There are no particular restrictions on the method of forming the metal coating, but it is preferable to use a plating method. There are no particular restrictions on the metal coating as long as it is a soluble metal, but C
It is preferable to use a low melting point metal such as u, Zn, or Sn. On the other hand, as the metal film forming the electrode, it is preferable to use a metal such as Cu, Au, Zn, or Sn, which is easy to solder. Furthermore, since flame retardancy is required for the protective film, it is preferable to use silicone.

[0009]

[Examples] Examples of the present invention will be described below. Example 1 An alumina ceramic substrate (manufactured by Hitachi Chemical, trade name Halox 552, dimensions 3.2 x 1.6 x thickness 0.635) with through holes with a diameter of 0.8 mm (φ) formed at both ends.
mm) with a degreasing solution (manufactured by Hitachi Chemical, trade name: HCR-20
1), and after drying, the alumina ceramic substrate was roughened by immersing it in a NaOH melt heated to 350°C for 10 minutes, and the surface roughness was 3.2 μm Rmax as shown in Figure 3 (a). I got 2. After roughening, H2 with a concentration of 10% by weight
The surface of the alumina ceramic substrate 2 was immersed in SO4 solution for 5 minutes to neutralize it, and then washed with water and subjected to electroless copper plating for 2 hours to form a 4 μm thick copper coating 6 as shown in FIG. 3(b). Formed. As the electroless copper plating solution, L-59 (trade name, manufactured by Hitachi Chemical Co., Ltd.) was used.

After copper plating, a photosensitive resist film (manufactured by Hitachi Chemical Co., Ltd., trade name PHT-862AF-25) is attached to the entire surface of the copper coating 6, and a pattern having the same shape as the conductor circuit to be obtained is further applied to the upper surface of the copper coating 6. A negative film (not shown) on which a transparent portion was formed was attached to the substrate, and the photosensitive resist film provided under the transparent portion of the negative film was cured by exposure. Next, the negative film was removed, and the photosensitive resist film was removed from the areas that had not been developed and cured, specifically, the areas that had not been exposed, to form a resist film 10 as shown in FIG. 3(c). Then concentration 2
Etching was performed using a 5% by weight ammonium persulfate solution to remove the copper coating 6 from unnecessary portions of the conductor circuit, as shown in FIG. 3(d). After this, N with a concentration of 5% by weight
The photosensitive resist film cured with the aOH solution is peeled off, and a conductor circuit (fusible part) is formed as shown in FIG. 3(e).
A ceramic wiring board on which electrodes 3 and 4 were formed was obtained.

Next, the ceramic wiring board is washed with water, dried, and then printed on the upper surface of the conductor circuit 3 and the alumina ceramic substrate 2.
A silicone resin (manufactured by Toray Dow Corning, trade name SE-1700) was applied to a thickness of 60 μm on the upper exposed surface of the film, and cured in an oven at 130°C for 15 minutes, as shown in Figure 3(f). A silicone protective film 9 was formed thereon. Next, degreasing liquid (manufactured by Hitachi Chemical, trade name HCR-201)
After washing with water, it was immersed in an H2SO4 solution with a concentration of 10% by weight for 1 minute, and after washing again with water, electroless nickel plating and gold plating were applied by conventionally known methods, as shown in FIG. 3 (g), respectively. A chip type fuse substrate was obtained in which a nickel film 7 and a gold film 8 of 2.0 μm and 0.1 μm were formed. The electroless nickel plating solution used was S-680 (trade name, manufactured by Nippon Kanigen Co., Ltd.), and plating was carried out at a bath temperature of 70°C for 10 minutes. Plating was performed at a temperature of 90°C for 10 minutes. The chip-type fuse board thus obtained was processed using a sling machine (manufactured by DISCO, product name: DAD).
-2H-6) was used to cut both ends to obtain the chip type fuse 1 shown in FIGS. 1 and 2. Note that in FIGS. 1 and 2, 5 is a through hole. The conductor circuit 3, which is the fusible portion of the obtained chip-type fuse, had a width of 60 μm, a thickness of 4 μm, and a length of 18 mm.

Comparative Example 1 An alumina ceramic substrate similar to that in Example 1 was roughened in the same manner as in Example 1 to obtain a surface roughness of 1.5 μm Rma.
An alumina ceramic substrate of x was obtained. Thereafter, a chip type fuse was obtained through the same steps as in Example 1. The conductor circuit of the obtained chip type fuse has a width of 60 μm and a thickness of 4 μm.
and the length was 18 mm.

Comparative Example 2 The same alumina ceramic substrate as in Example 1 was used, except that it was immersed in KOH melt as a roughening solution for 30 minutes.
A chip type fuse using an alumina ceramic substrate with a surface roughness of 8.5 Rmax was obtained through the same process as above. The width of the conductor circuit of the obtained chip type fuse was 60 μm,
The thickness was 4 μm and the length was 18 mm.

Next, using 20 chip-type fuses obtained in Examples and Comparative Examples, the resistance value of the conductor circuit portion, the adhesion strength of the electrode portion, and the fusing time when a current of 2 A was applied were determined. The results are shown in Table 1.

[0015]

[Table 1]

As is clear from Table 1, the chip type fuse according to the example of the present invention is superior to the chip type fuse of the comparative example in the adhesion strength and fast-acting property of the electrode portion.

[0017]

[Effects of the Invention] According to the present invention, a chip type fuse for preventing accidents such as overheating of electronic equipment and fire due to overcurrent caused by failures such as malfunctions and short circuits of electronic equipment can be manufactured while maintaining mass productivity. It is possible to provide a chip-type fuse suitable for protecting electronic equipment, which has excellent adhesion strength of electrode portions, improved fast-acting properties, and improved stability of characteristics.

[Brief explanation of the drawing]

FIG. 1 is a slanted view of a chip-type fuse according to an embodiment of the present invention.

FIG. 2 is a sectional view taken along the line AA in FIG. 1;

FIG. 3 is a cross-sectional view showing a manufacturing process of a chip-type fuse according to an embodiment of the present invention.

[Explanation of symbols]

1 Chip type fuse 2 Alumina ceramic substrate 3 Conductor circuit 4 Electrode 5 Through hole 6 Copper coating 7 Nickel coating 8 Gold coating 9 Silicone protective film 10 Resist film

Claims (1)

[Claims] 1. After roughening the surface of a ceramic substrate so that the surface roughness is 2 to 6 μm Rmax, a metal coating is formed on the surface of the ceramic substrate, and then a resist film is formed on the top surface of the metal coating. After that, the resist film is peeled off by exposure, development, etching, and a conductor circuit and electrodes are formed leaving only the necessary parts of the metal coating, and a protective film is formed on the upper surface of the conductor circuit and the upper exposed surface of the ceramic substrate. ,
A method for manufacturing a chip-type fuse, which is characterized by molding it into a chip.