JPH04245132A - Base for chip fuse and chip fuse using it - Google Patents

Abstract

PURPOSE:To provide a base having good mass productivity of a chip fuse and the chip fuse excellent in its quick fusion by using said base. CONSTITUTION:A base for a chip fuse on the chemically cut photosensitive glass plate of which slits 12 for dividing the base into a number of chip fuses, are formed, and a chip fuse in which two electrodes 10 opposing to each other for every chip fuse and a fuse metal film 11 electrically connecting said electrodes to each other are arranged on the base 6 for said chip fuse.

Description

[Detailed description of the invention]

0001

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a chip fuse substrate used in electronic equipment and the like, and a chip fuse using the same.

0002

[Prior Art] Conventionally, fuses used to prevent electronic equipment from overheating, fires, accidents, etc. due to overcurrent caused by malfunctions such as incorrect operation or short circuits have a cap-shaped external connection on both ends of a glass tube. There was a tube fuse in which terminals were provided and fuse metal was connected between the terminals inside the glass tube. However, as electronic devices become smaller, the area occupied by the tube fuse becomes larger, which has become a problem. To solve this problem, a chip type fuse that can be surface mounted on a board has been proposed (Japanese Unexamined Patent Application Publication No. 172-172-1982, Japanese Unexamined Patent Publication No. 62-17
No. 2625, No. 62-172629, etc.). In the method disclosed in these publications, after forming an electrode 10 on the surface of an insulating alumina ceramic 14 in the shape of a rectangular parallelepiped chip as shown in FIG.
This wire is used as a fuse metal, and the wire is protectively coated with resin potting to form a fuse. In addition, in the figure, 5 is a through hole. However, this method not only complicates the manufacturing process because the terminal electrodes and fuse metal for electrical connection with external circuits are formed separately, but also has a disadvantage compared to chip components such as general chip resistors and chip capacitors. Due to its complicated shape, it was not suitable for automatic mounting on the surface of a circuit board. Also, when manufacturing
When using insulating alumina ceramic that is pre-cut into a single chip shape, each chip is too small, making it difficult to handle.In general, in order to increase mass production, multiple chip fuse elements are formed at once and then individually cut. Alumina ceramics are generally very rigid, so dicing with a laser or a blade coated with diamond powder is used to separate them. However, both division methods require a large amount of work time, leading to an increase in manufacturing costs. On the other hand, as a chip fuse suitable for automatic mounting on the surface of a circuit board, a method as shown in Japanese Patent Laid-Open No. 63-141233, shown in FIG. 6, has been proposed. That is, FIG. 8(a) is a cross-sectional view of the chip fuse, and FIG. 8(b) is a diagram showing the relationship between the electrode and the fuse metal. A pair of electrodes 10, 10 are provided at both ends,
A fuse metal film 11 having a pattern as shown in the figure (b) is formed between the electrodes in a planar manner on the surface by a plating method or a thick film method. Note that 16 is a covering layer.

0003

[Problems to be Solved by the Invention] However, the method disclosed in Japanese Patent Application Laid-Open No. 63-141233 is
This is an improved method for forming electrodes and fuse metals compared to the methods shown in Publications No. 2-172624, No. 62-172625, and No. 62-172629. In this case, the only way to divide the final product is by laser or dicing, and the manufacturing cost for dividing is the same as the methods shown in the above three publications. In addition, in order to increase the connection reliability when surface mounting a chip fuse, it is necessary to form terminal electrodes in the longitudinal direction of the chip on the back side of the chip fuse via the side surface of the chip. Particularly difficult problems arise when performing side metalization after separation. In other words, when forming sidewall metallization to connect the front and back electrodes using electroless plating, it is partial plating, which requires new steps such as forming a plating resist, forming an etching resist, and etching process, which increases the cost. It's going to be up. In addition, in the case of the thick film method, when using normal thick film paste for side metallization, 8
There is a problem in that heat treatment at around 50° C. is required, and the silicone resin coated on the fuse metal deteriorates. Further, when using a thick film paste that cures at around 180° C., there is a problem that the wettability and adhesion of the solder are unreliable. Further, in the case of a manufacturing method in which side through holes are formed in advance, it is necessary to form the holes in a multi-hole sheet. The holes are usually formed by punching holes in a sheet before sintering and then sintering them to obtain an alumina ceramic substrate with holes formed at the required positions, or by laser-cutting the sintered alumina ceramic substrate afterwards. A method of drilling holes is used. However, in the method of obtaining a perforated alumina ceramic substrate by sintering a perforated raw sheet, the sintering shrinkage rate of the alumina ceramic substrate generally varies by about 1%. There is a problem in that the positions of the holes in the ceramic substrate do not match, resulting in poor yield. In addition, when drilling holes in a sintered alumina ceramic substrate using a laser, although the hole position accuracy is good, there are problems such as re-adhesion of evaporated alumina ceramic near the hole and the large cost required to drill the hole. . Furthermore, in applications that require fast-acting performance, the fuse metal to be blown is in direct contact with the alumina ceramic substrate, which has good thermal conductivity. However, there is a problem in that it lacks quick cutting performance when an overcurrent flows. On the other hand, there are printed boards that have poor thermal conductivity and have established bonding and processing methods for copper, etc., but although they have excellent fast-acting properties, the melting point at which fuse metals such as copper melt is high, and the heat resistance temperature of the fuse support board is low. However, there are problems such as deterioration of the supporting board due to heat generated by the fuse, danger of smoke generation, and ignition.

The present invention has been made in view of the above-mentioned disadvantages, and has excellent fast-acting properties when overcurrent flows through the fuse portion, easy opening and splitting in the manufacture of fuses, and excellent mass productivity. The present invention provides a chip fuse substrate and a chip fuse using the same.

[0005]

[Means for Solving the Problems] The inventors have achieved the following by using a chemically cuttable photosensitive glass plate instead of the conventional alumina ceramic etc. as an insulating substrate of a chip fuse.
When used as a fuse, the fuse has excellent fast-acting properties when overcurrent flows through the fuse due to an abnormality such as a short circuit.
In addition, the inventors have found that the method is excellent in mass production because the splitting properties and the formability of through-holes for side metallization are improved in fuse manufacturing, and the present invention has been completed.

The present invention provides a chip fuse substrate in which a chemical cutting photosensitive glass plate is formed with slits to divide it into a large number of chip fuses, and a chip fuse substrate with two electrodes facing each other for each chip fuse and the electrodes. This invention relates to a chip fuse provided with a fuse metal film that electrically connects the fuse.

[0007] In the present invention, the composition of the chemically cuttable photosensitive glass plate is not particularly limited as long as it can precipitate crystals that are easily soluble in HF by an appropriate heat treatment after local exposure to ultraviolet rays, and SiO2-Li2O. -Al2O3 system is well known. This glass is made of Li2, which is easily soluble in HF, by local exposure to ultraviolet rays and subsequent heat treatment.
O.SiO2 crystals are precipitated in the exposed area, so by immersing this glass plate in an HF solution, Li2O.SiO2 crystals are precipitated in the exposed area.
By eluting the second part, it is possible to process through holes and slits.

Therefore, the chip fuse substrate of the present invention has the following features:
A chemically cuttable photosensitive glass plate (hereinafter referred to as photosensitive glass) is irradiated with ultraviolet light by applying a mask that exposes only the through holes in the electrode terminals and the slits that divide the chip fuses. Then, heat treatment is performed at, for example, 550°C (primary heat treatment) to precipitate Li2O/SiO2 crystals on the exposed area, followed by immersion in an HF solution to dissolve and remove the precipitated crystals, and finally heat treatment at, for example, 800°C (secondary heat treatment). (Second heat treatment) Obtained by crystallizing the entire glass. The material of the mask for local exposure may be any material as long as it can form a part that transmits ultraviolet rays and a part that blocks ultraviolet rays, and usually a mask made of a transparent quartz glass plate coated with a Cr vapor deposition film is used. In ultraviolet irradiation, the exposure width of the slit part is made sufficiently narrow to supply HF to the narrow slit and dissolve Li2O/SiO.
It is preferable to slow down the removal rate of the two crystals so that a slit 12 having a depth suitable for manual division as shown in FIG. 6 is formed in the photosensitive glass 1 when the through hole penetrates. In addition, by making the amount of exposure to the portion corresponding to the slit smaller than the amount of exposure to the portion corresponding to the through hole, the amount of Li2O/SiO2 crystal precipitation during heat treatment is reduced, and the processing speed of the slit portion during HF immersion is reduced. It is preferable that the through-hole opening speed be slower than the through-hole opening speed. For this reason, a method is used in which a material that absorbs some ultraviolet rays, such as a Lumirror film, is placed over the slit portion and irradiated.

When chemically machinable photosensitive glass is crystallized through secondary heat treatment, the density of the glass increases as it crystallizes and it shrinks in size, but the shrinkage rate is approximately 1%, which is an order of magnitude smaller than that of alumina, so it is not suitable for fuses. High dimensional accuracy as a forming substrate. Furthermore, since the specific heat, thermal conductivity, and density are lower than those of alumina, the rate of heat diffusion when the fuse generates heat is slow, which has the advantage of shortening the abnormal current flow time until the fuse reaches the melting point.

[0010] The electrodes and fuse metal film are formed on the chip fuse substrate by printing a paste-like conductor using a known pressure film method such as screen printing, heat-treating it, roughening the surface, plating it, and then photolithography. , an etching method is used. In the latter method, the surface may be roughened by immersion in a known fluoride solution. The plating is performed by electroless plating and, if necessary, electroplating to make the plating thickness uniform within the through hole and on the surface. After plating, photolithography and etching are performed using known methods to form a chip fuse connection body. The electrodes are made of conductive metal, and the fuse metal is appropriately selected from metals that melt when an overcurrent occurs, and gold, silver, copper, or an alloy thereof is usually used.

[0011] The chip fuse is obtained by manually dividing the above-mentioned chip fuse assembly from the slit portion.

0012

[Examples] Examples of the present invention will be described below.

Example 1 As shown in FIG. 1(a), a 60x6
0mm photosensitive glass (manufactured by Sumita Optical Glass, PSG-1
) 0.7mm square through hole shape and 15μ on top of 1
There is an ultraviolet transmitting part without a Cr vapor deposited film in the part corresponding to the m-wide slit, and a transparent quartz glass mask 2 coated with a Cr vapor deposited film 3 is superimposed on the other part. Precision exposure device ORCHMW-661B-
1, parallel ultraviolet light was irradiated at 10 J/cm2. Next, the glass plate exposed to ultraviolet rays was placed in a heat treatment furnace, and as a primary heat treatment, it was heated to 545°C in the air and held for 3 hours, and as shown in Figure 1(b), Li2O.
SiO2 crystal 4 was deposited. Next, this glass plate was immersed and stirred in a 6% by weight HF aqueous solution for 90 minutes, the precipitated crystal portion was dissolved, washed, dried, and then placed in a heat treatment furnace again and heated at 810°C for 2 hours as a secondary heat treatment. was crystallized to obtain a chip fuse substrate 6 having through holes 5 shown in FIG. 1(c) and slits (not shown).

Next, this substrate was heated to 10% by weight H at a liquid temperature of 30°C.
The surface was roughened by immersing it in an F aqueous solution for 10 minutes and stirring. Next, this substrate was washed with running water, immersed in a 30% by weight HCl aqueous solution for 1 minute, and then treated with a sensitizer (manufactured by Hitachi Chemical, HS-10).
1B) for 5 minutes and then washed with running water. Next, this was immersed in an adhesion promoter (manufactured by Hitachi Chemical, ADP-201) for 5 minutes, and after washing with running water, it was immersed in an electroless plating solution (manufactured by Hitachi Chemical, L-59) heated to 70°C for 2 hours. , 4 μm of copper plating was applied to obtain a substrate having a copper plating film 7 shown in FIG. 1(d). After that, as shown in Figure 1(e), a photosensitive resist film (manufactured by Hitachi Chemical Co., Ltd., PHT-862AF-40) was used.
8 was closely attached to the copper plating 7, a conductor forming mask 9 corresponding to the fuse pattern and the electrode pattern was placed, and after exposure to ultraviolet rays, development was performed with a 1% by weight Na2CO3 aqueous solution, and then the copper was etched with a copper chloride aqueous solution. Then, the resist film 8 was peeled off to obtain a connected body of chemically cutable photosensitive glass chip fuses having a fuse metal film 11 and an electrode 10 having a pattern as shown in FIG. Thereafter, it was divided through the slit 12 to obtain a plurality of chip fuses.

Example 2 In the same manner as in Example 1, a mask 2 was placed on a photosensitive glass 1 as shown in FIG. Thickness 188μ to sufficiently cover
m polyethylene terephthalate film (manufactured by Toray,
Lumirror (trade name) 13 were stacked and then subjected to ultraviolet irradiation and primary heat treatment in the same manner as in Example 1 to form L as shown in Figure 3(b).
The i2O/SiO2 crystal 4 was precipitated, then HF etched, and then subjected to secondary heat treatment at 650°C for 5 hours to form the structure shown in Fig. 3.
As shown in (c), the through hole hole 5 and the slit 12
A chip fuse substrate 6 having the following was obtained. DuPont Copper Paste 992 was then applied using a conventional thick film screen printing method.
2 is printed on the front surface, back surface, and inside the through hole, and baked to form the electrode 10 and the fuse metal film 1 in the shape shown in FIG.
A chemically cutable photosensitive glass chip fuse connector having a chemical cutting property of No. 1 was obtained. Next, it was divided through the slit 12 to obtain a plurality of chip fuses.

Comparative Example A chip fuse substrate (Halox 552 manufactured by Hitachi Chemical Co., Ltd.) in which a through hole with a diameter of 0.8 mm was opened in the same position as in Example 1 on a 96% alumina substrate of 60 x 60 mm with a thickness of 0.635 mm. ) was prepared. Then, after washing with degreasing liquid HCR-201 manufactured by Hitachi Chemical, washing with water, and drying,
After roughening the surface by immersing it in a NaOH melt heated to ℃ for 5 minutes, it was immersed in a H2SO4 solution with a concentration of 10% by weight for 5 minutes, and ultrasonic vibration energy with an output of 300 W was applied to neutralize the ceramic surface. . Next, copper plating, photolithography, and etching were performed under the same conditions as in Example 1 to obtain a ceramic chip fuse connector having the same pattern of fuse metal film and electrode as in Example 1. Thereafter, it was cut using a slicing machine (DAD-2H-6, manufactured by DISCO) to obtain a plurality of chip fuses.

[0017] The chip fuses obtained in Example 1 and Comparative Example were subjected to a DC fusing test in accordance with the method specified in JIS C8352 to confirm their fast blowing properties. The results are shown in FIG. As is clear from FIG. 5, Example 1
The chip fuse blows faster. That is, even if the structure (quality and pattern) of the fuse is the same, rapid blowing performance is improved by replacing the support substrate of the fuse with photosensitive glass, which has lower specific heat, thermal conductivity, and density than alumina ceramic.

[0018]

Effects of the Invention The chip fuse substrate of the present invention has through-holes and slits dividing it into a large number of chip fuses in a chemically cuttable photosensitive glass plate, so it is excellent in mass production of chip fuses with good dimensional accuracy. Moreover, the chip fuse has excellent fast-acting properties.

[Brief explanation of the drawing]

FIG. 1 is a diagram showing the manufacturing process of a chip fuse according to an embodiment of the present invention.

FIG. 2 is a plan view of a chip fuse according to an embodiment of the present invention.

FIG. 3 is a diagram showing a manufacturing process of a chip fuse according to an embodiment of the present invention.

FIG. 4 is a plan view of a chip fuse according to an embodiment of the present invention.

FIG. 5 is a graph showing the blowing characteristics of a chip fuse.

FIG. 6 is an enlarged view showing how slits are formed.

FIG. 7 is a diagram showing a conventional chip fuse.

FIG. 8 is a diagram showing a conventional chip fuse.

[Explanation of symbols]

1 Photosensitive glass 2 Mask 3 Cr vapor deposited film 4 Li2O/SiO2 crystal 5 Through hole 6 Chip fuse board 7 Copper plating film 8 Photosensitive resist film 9 Conductor formation mask 10 Electrode 11 Fuse metal film 12 Slit 13 Film 14 Alumina ceramic 15 Wire 16 Coating layer

Claims (2)

[Claims] 1. A chip fuse substrate, in which a chemically cuttable photosensitive glass plate is formed with slits for dividing it into a large number of chip fuses. 2. A chip fuse, wherein the chip fuse substrate according to claim 1 is provided with two opposing electrodes and a fuse metal film for electrically connecting the electrodes.