JPH04248222A - Manufacture of chip type fuse - Google Patents

Abstract

PURPOSE:To quickly find a fused place by utilizing a Cu coat formed through a process of plating with the aid of a photo-etching process to form electrodes and conductor circuits respectively, and thereafter utilizing a printing process to form a protective coat being discolored with a rise in temperature. CONSTITUTION:The surface of a ceramic substrate 2 formed collectively with a plurality of chip type fuses is roughed to form a Cu coat through a process of electroless plating. A resist coat is formed on the top face of the Cu coat to go through processes of exposure, development, etching and peeling the resist coat, and thereafter only the required part of the Cu coat is left to form each of conductor circuits 3 and each of electrodes 4 respectively. A protective coat 9 which can be discolored with a rise in temperature to detect the presence or absence of a fused place is formed on the top face of the circuit 3 and the top disclosed face of the substrate 2 respectively. Furthermore, Ni plating 7 and Au plating 8 are given to the top face of the electrode 4 and thereafter the substrate 2 is divided into separate pieces to be each formed in the shape of a chip.

Description

[Detailed description of the invention]

0001

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

0002

2. Description of the Related Art Generally, electronic circuit components are provided with fuses to prevent overcurrent from flowing and damage. In recent years, chip-type fuses have been developed for direct mounting on printed circuit boards and the like.

As a conventional method for manufacturing a chip type fuse using a ceramic substrate, there is a method as disclosed in Japanese Patent Application Laid-open No. 172626/1983. This chip type fuse has electrodes on both ends of the chip, a metal wire for the fuse is connected between these electrodes, and a protective film is formed on the top surface of the metal wire for the fuse by using transparent resin and curved into a lens shape. has been done. Therefore, the internal fuse metal wire is seen through the convex lens-shaped protective film. As a result, the image of the internal fuse metal wire is enlarged due to the light refraction effect of the protective film, thereby doubling the effect of seeing through.

[0004] In chip-type fuses with a general structure, the positive and abnormal states of the chip-type fuse can be confirmed from the outside at a glance, and it is possible to discover the blown state of the metal wire melted by heat caused by overcurrent. I can do it.

[0005]

[Problems to be Solved by the Invention] However, the above-mentioned chip type fuse has electrodes provided at both ends of the chip, a metal wire for the fuse is connected between these electrodes, and a transparent resin is further coated on the top surface of the metal wire for the fuse with a convex lens. The yield was lowered due to the formation of a shape, which hindered mass production. In addition, if a chip type fuse is extremely small and the structure of the part that becomes the fuse is minute and complicated, when an overcurrent flows and the metal wire melts, it cannot be confirmed at first glance. There was a drawback that replacement work could not be performed.

SUMMARY OF THE INVENTION An object of the present invention is to provide a method for manufacturing a chip-type fuse that does not have the above-mentioned drawbacks.

[0007]

[Means for Solving the Problems] As a result of various studies on the above-mentioned drawbacks, the present inventors formed electrodes and conductive circuits using a Cu film formed by a plating method using a photo-etching method. However, if we use a printing method to form a protective film that changes color as the temperature rises and allows us to detect whether or not it has blown out, we can quickly find the location where it has blown out due to overcurrent, and we can also create a chip-type fuse that has excellent automatic mounting. I discovered that it can be manufactured.

The present invention roughens the surface of a ceramic substrate on which a plurality of chip-type fuses are to be formed at once, forms a Cu film by electroless plating, and then forms a resist film on the top surface of the Cu film. After that, exposure, development, etching, and peeling off of the resist film were performed to form a conductor circuit and electrodes, leaving only the necessary portions of the Cu film, and then the upper surface of the conductor circuit and the upper exposed surface of the ceramic substrate were heated to A chip-type fuse in which a protective film is formed that changes color as it rises and can detect the presence or absence of fusing, and further Ni plating and Au plating are applied to the upper surface of the electrode, and then the ceramic substrate is individually divided and formed into chips. Relating to a manufacturing method.

In the present invention, the materials used for the ceramic substrate include alumina, PZT (based on lead, zirconia, and titanium), mullite, aluminum nitride, and the like.

[0010] There are no particular restrictions on the method of roughening the surface of the ceramic substrate, but if the ceramic substrate is roughened by immersing it in an alkaline melt heated to a temperature above its melting point for 30 seconds or more, the workability is excellent. Further, it is preferable because there is little variation and uniform roughening can be achieved.

[0011] The Cu film is formed by electroless plating, and electroplating requires lead terminals, which makes the process complicated and causes variations in the thickness of the plating. The disadvantage of this method is that it requires special equipment and is therefore expensive.

The protective film is not particularly limited as long as it can be formed using a material that changes color due to temperature rise and can detect the presence or absence of fusing, but phthalocyan green (C32Cl16
N8Cu), Hansaiero (C17H16N4O4)
It is preferable to use a material containing pigments such as the following, since there is less variation in discoloration and the location of fusing can be quickly discovered.

[0013]

[Examples] Examples of the present invention will be described below. Example 1 As shown in FIG. 3(a), an alumina ceramic substrate (manufactured by Hitachi Chemical Co., Ltd., product Name Harox 552, dimensions 80 x 80 x thickness 0
．． 635mm) 2 with degreasing liquid (manufactured by Hitachi Chemical, trade name H
After washing with CR-201) and drying, add 10 g of NH4F (40
．． 5% by weight), (NH4)2SO41g (4.1% by weight
), 42 ml of concentrated H2SO (14.9% by weight) and H2O
10ml (40.5% by weight) mixed solution (liquid temperature 70°C)
Roughening was performed by immersing the sample in the water for 10 minutes. Note that (a) in Figure 3
11 is a board dividing section.

[0014] Next, wash thoroughly under running water, dry and dry at 380℃.
Re-roughening was performed by immersing the sample in a NaOH melt heated to ℃ for 3 minutes. Thereafter, the surface of the alumina ceramic substrate 2 is immersed in a H2SO4 solution with a concentration of 10% by weight for 3 minutes, and vibration energy is applied by ultrasonic waves (output 300W) to neutralize the surface. Then, the surface of the alumina ceramic substrate 2 is washed with water to perform electroless Cu plating. After 4 hours, as shown in FIG. 3(b), a Cu coating 6 with a thickness of 9 μm was formed.
was formed. In addition, the electroless Cu plating solution has a pH of 12.4.
The composition shown in Table 1 was used.

[0015]

[Table 1]

After Cu plating, a photosensitive resist film (manufactured by Hitachi Chemical Co., Ltd., trade name PHT-862AF-25) is pasted on the entire surface of the Cu film 6, and a transparent resist film in the same shape as the conductor circuit to be obtained is further applied on the upper surface. After attaching a negative film (not shown) on which a transparent portion was formed, the photosensitive resist film disposed on the lower surface of the transparent portion of the negative film was cured by exposure. Next, the negative film is removed, and the photosensitive resist film in the areas that have not been developed and cured, specifically, the areas that are not exposed, is removed, and the photosensitive resist film is removed as shown in Figure 3 (c).
A resist film 10 as shown in ) was formed. Thereafter, etching was carried out using a solution of ammonium persulfate having a concentration of 25% by weight to remove portions of the Cu film 6 which were unnecessary as conductor circuits, as shown in FIG. 3(d).

After that, the photosensitive resist film cured with a 5% by weight NaOH solution was peeled off, and the photoresist film (e) in FIG. 3 was peeled off.
), a ceramic wiring board was obtained in which conductor circuits 3 and electrodes 4 were formed simultaneously.

Next, the ceramic wiring board is washed with water, and after drying, a protective material (Hitachi Manufactured by Kasei Kogyo, product name HPD-
4) was applied to a thickness of 60 μm and heated in an oven at 180°C.
This was cured for 30 minutes to form a protective film 9 as shown in FIG. 3(f).

[0019] Next, a degreasing liquid (manufactured by Hitachi Chemical Co., Ltd., trade name H
CR-201) and after washing with water, H2 with a concentration of 10% by weight
After being immersed in SO4 solution for 1 minute and washed with water again, conventionally known electroless Ni and Au plating was applied to form Ni coatings 7 with thicknesses of 2.0 μm and 0.1 μm, respectively, as shown in FIG. 3(g). A chip type fuse substrate on which a coating 8 of Au was formed was obtained. The electroless Ni plating solution used was S-680 (trade name, manufactured by Nippon Kanigen Co., Ltd.) at a bath temperature of 70°C for 10 minutes, and the electroless Au plating solution was Lectroreprep (trade name, manufactured by EEJA), and the bath temperature was 90°C. I went there for 10 minutes.

The chip-type fuse board thus obtained was processed using a slicing machine (manufactured by DISCO, product name: DA).
D-2H-6), the board was divided into individual parts at the board dividing part 11, and the individual dimensions were 3.2 x 1.6 mm in Figures 1 and 2.
Chip type fuse shown in (rated current 300mA product, resistance of conductor circuit part 0.8Ω, conductor circuit thickness 9.0μm,
A conductor circuit width of 50 μm and conductor circuit length of 18 mm) 1 was obtained.

Next, the chip type fuse 1 obtained above was
The appearance after fusing was observed. The measurement method is constant current 3
A (direct current equivalent to 10 times the rated current) was applied to both ends of the electrode of the chip type fuse 1 to blow out the fuse (conductor circuit 3), and the appearance at this time was observed. As a result, the protective film at the melting point changed color from green to brown, and
Abnormal states of all 0 fuses could be confirmed at a glance.

Comparative Example 1 Transparent resin (manufactured by Toray Dow Corning, trade name SE-17)
00) was used to form a convex lens-shaped protective film.
A chip type fuse was obtained through the same steps as in Example 1. Then, a fusing test similar to that in Example 1 was conducted using ten of the obtained chip-type fuses, and the appearance after fusing was examined. As a result, it was difficult to confirm the location of the melt.

Example 2 The same process as in Example 1 was carried out, except that a protective film was formed using a protective material (manufactured by Hitachi Chemical, trade name HPD-3) that changes color due to temperature rise and can detect the presence or absence of fusing. A chip-type fuse was obtained through the process. Then, a fusing test similar to that in Example 1 was conducted using ten of the obtained chip-type fuses, and the appearance after fusing was examined. As a result, the protective film at the melted location changed color from yellow to brown, and the abnormal conditions of all 10 fuses could be confirmed at a glance.

[0024]

[Effects of the Invention] The chip-type fuse obtained by the manufacturing method of the present invention can quickly find the location where it has blown due to heat caused by overcurrent, so repair processing can be easily carried out, and the yield is improved, making it suitable for mass production. This is an industrially very suitable chip type fuse.

[Brief explanation of the drawing]

FIG. 1 is a perspective 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 Cu coating 7 Ni coating 8 Au coating 9 Protective film 10 Resist film 11 Board division part

Claims (1)

[Claims] 1. Roughening the surface of a ceramic substrate on which a plurality of chip fuses are to be formed at once, forming a Cu film by electroless plating, and then forming a resist film on the top surface of the Cu film, After that, exposure, development, etching,
After removing the resist film and forming a conductor circuit and electrodes by leaving only the necessary parts of the Cu film, the upper surface of the conductor circuit and the upper exposed surface of the ceramic substrate change color due to temperature rise, and the presence or absence of fusing is detected. 1. A method for manufacturing a chip-type fuse, which comprises forming a protective film and further plating the upper surface of the electrode with Ni and Au, and then dividing the ceramic substrate into individual pieces and forming them into chips.