JPH02126530A - Chip fuse - Google Patents

Abstract

PURPOSE:To easily make the size of fuse small and perform the surface mounting by installing electrodes on an insulating heat resistant substrate and connecting them with a fuse actor. CONSTITUTION:Electrodes 2 are installed on an insulating heat resistant substrate 1 of ceramics, etc., and they are connected with a fuse actor 3. The fuse actor 3 is, therefore, protected by an insulating heat resistant substrate 1, so that it has a sufficient resistance against heat generated when the electrode 2 is soldered. Thereby, solder dip and solder reflow become possible; as a result, the surface mounting can be accomplished. Moreover, it is possible to carry out fine working and make the size of fuse small by installing the fuse actor 3 by vacuum evaporation or wire bonding.

Description

[Detailed description of the invention] (Industrial application field) The present invention relates to chip fuses.

(Prior art) Fuses include those that use a metal wire as a fuse acting body and enclose the metal wire in a glass tube so that the metal wire melts due to heat generation (tubular fuse); A layer of a low melting point substance such as a thermoplastic resin or an organic layer is formed, and a conductive material is provided on this layer, and when the conductive material generates heat, the low melting point substance melts and the low melting point substance changes shape. There are fuses in which the conductive material is disconnected (indirectly operated fuses).

The metal wire used for the tubular fuse has a low melting point, such as Sn, [3i, Cd, Pb, In
Zn, Δ!, etc., have high melting points. ,ΔJ? , Cu
, Fa, Pt, etc. alone or alloys are used. When connecting a tubular fuse to a circuit, a fuse holder is used.

In addition to the single fuse components mentioned above, chip capacitors and resistors containing fuses or substances that act as fuses are also commercially available.

(Problems to be Solved by the Invention) By the way, in the above-mentioned conventional fuse parts, tube type fuses,
However, it is difficult to miniaturize the metal wire due to the structural constraints of enclosing it in a glass tube, and because the metal wire is often made of a low-melting point substance, it cannot withstand the heat during soldering. Not suitable for surface mounting.

Indirectly operated fuses use a low melting point material such as thermoplastic resin, so they cannot withstand the heat during soldering and are not suitable for surface mounting. In addition, during manufacturing, a process of applying a low melting point substance onto the substrate is required, which takes a lot of man-hours, and the wire breaks due to a change in shape when the low melting point substance melts, so the fusing characteristics are inevitably inconsistent. , there are problems such as increased variation.

Furthermore, in conventional resistors with built-in fuses, the size is inevitably increased due to the addition of the fuse portion.

In recent years, electronic components have become more and more densely packed, and the components mounted on electrical devices are also required to be smaller in size. Therefore, there is a need for fuses used in these devices that are small, have excellent characteristics, can withstand 1 minute of heat from soldering, etc., and can be easily surface-mounted. .

Therefore, the present invention was made in view of these problems, and its [1] object is that it can be easily miniaturized.
The aim is to provide a chip fuse that can also be surface mounted.

(Means for Solving the Problems) The present invention has the following configuration to achieve the above object.

That is, the present invention is characterized in that electrodes are provided on an insulating heat-resistant substrate such as ceramics, and the electrodes are connected by a fuse acting body. The fuse acting body is provided as a metal film layer obtained by depositing a metal having predetermined fusing characteristics between the electrodes by vacuum evaporation on an insulating heat-resistant substrate on which electrodes are formed, or Preferably, a metal wire having a predetermined fusing characteristic is used as the fuse effecting body, and the metal wire is wire-bonded between electrodes of an insulating heat-resistant substrate on which electrodes are formed.

(Function) The fuse effecting body is protected by the insulating heat-resistant substrate, so it has sufficient resistance to the heat generated when soldering the electrodes. This enables solder dip and solder reflow, making surface mounting possible. Also, by providing a fuse effecting body by vacuum deposition or wire bonding.

Fine processing becomes possible and the size of the fuse can be reduced.

(Embodiments) Hereinafter, preferred embodiments of the chip fuse according to the present invention will be described in detail based on the accompanying drawings.

<Embodiment 1> Fig. 1 shows an example in which a thin film metal material is used as the fuse effecting body, Fig. 1(a) is a side sectional view of the chip fuse, and Fig. 1(b) is its plan view. It is.

In the figure, reference numeral 1 denotes a substrate having electrical insulation and heat resistance, and in the embodiment, a flat plate made of alumina ceramics is used. Reference numeral 2 denotes electrodes formed at both ends of the substrate 1 in the longitudinal direction. In the example, a Δg/Pd-based thick film conductor is printed on the alumina ceramic substrate Y,
It was fired at 850°C to form an electrode. The electrode 2 is provided on the upper and lower surfaces of the substrate, covering the side edges of the substrate, and on the upper surface of the substrate,
Connection portions 2a with the fuse effecting body are provided facing each other and extending slightly. The material of the electrode 2 is not particularly limited as long as it is a heat-resistant conductor.

3 is the connection part 2a, 2 of the electric current t@2.2 on the board L
This is a fuse effecting body formed in a thin film shape between a and a. In the example, a metal containing Δg as a main component was provided as a thin film layer on the substrate 1 by vacuum evaporation. As shown in FIG. 1(b), the fuse effecting member 3 has a wide joint portion with the connecting portion 28, and a narrow central portion. During this vacuum deposition, a predetermined pattern is formed using a metal mask. In addition, as a method for forming the fuse effecting body 3, other methods such as printing a conductive paste and providing it can also be adopted.

4 is an insulating protector that covers the fuse effecting body 3. In the example, glass pastes 1 to 1 were printed on the upper surface of the fuse effecting body 3 by a screen printing method and fired at 600° C. to form the insulating protector 4.

In addition, a method such as molding an insulating resin as the insulating protector 4 may also be adopted.

As described above, this embodiment is characterized in that a metal thin film is used as the fuse effecting body 3, and the metal thin film layer serving as the fuse effecting body is provided on the insulating and heat resistant substrate 1. It goes without saying that the method of forming the electrode 2, the fuse effecting body 3, and the insulating protector 4 is not limited to two consecutive methods, but one of various methods can be applied.

In addition, the electrodes were formed by printing the thick film conductor described above, and the fuse acting body was formed by the blank evaporation method.J7f.

Printing a membrane glass paste to form a dielectric protector is an extremely efficient method for manufacturing chip fuses, and it is possible to pre-form large alumina ceramic substrates that can be divided into chip fuse sizes. Keep it
A large number of chip fuses can be formed at once by providing electrodes, fuse actuators, and insulating protectors using the method described in 2.1 and dividing them into individual pieces. Further, since it is based on screen printing or the like, it is easy to form fine particles, and even extremely small products can be manufactured easily.

The resistance value of the chip fuse in the above example was about 0.2Ω, and the wire broke when a DC voltage was applied and a current of about 4Δ flowed. Also, no change in fuse characteristics was observed in a test in which the product was immersed in a solder bath at 260°C.

In the chip fuse of this example, the fusing characteristics of the fuse acting body can be controlled by changing the vapor deposition material that forms the fuse acting body, changing the thickness of the deposited film, changing the pattern during vapor deposition, etc. can do.

<Embodiment 2> Fig. 2 shows an embodiment in which a metal wire is used as the fuse effecting body, with Fig. 2(a) showing a side sectional view and Fig. 2(b) showing a plan view.

In the figure, the configurations of a substrate 1, an electrode 2, and an insulating protector 4 are the same as in the first embodiment. Reference numeral 5 denotes a metal wire serving as a fuse effector connecting between electrodes 2.2. 6 In this example, an AU wire with a diameter of 25 μm was used as a fuse effector and was connected to electrode 2.2 by wire bonding. After this, thick film glass
A paste was applied and fired to form an insulating protector 4.

The resistance value of the obtained chip fuse was about 0.1Ω,
A DC voltage was applied to the rFr wire at a current of about 3.8 cm.

Further, no change in fuse characteristics was observed even after immersion in a solder bath at 260°C.

In this embodiment, the metal wire used as the fuse acting body is provided by the conventional wire bonding method, so it is easy to miniaturize the chip fuse, and automatic bonding can also improve production efficiency.

Note that the wire diameter of the metal wire used as the fuse acting body is 10
The fusing characteristics can be controlled by changing the thickness to .mu.m, 25 .mu.m, 50 .mu.m, etc., or by changing the metal wire material to .DELTA.1 other than .largecircle..

<Embodiment 3> Figure 3 shows another embodiment in which a metal wire is used as the fuse acting body. This is an example of a shape. In the figure, reference numeral 6 denotes electrodes, one electrode being provided on one opposing side and two electrodes provided on the other side. As shown in the figure, one metal wire serving as the fuse effecting body 5 is wire-bonded between each of the opposing electrodes 6. In the case of a mini mold transistor, a chip is mounted between opposing electrodes and wire bonded, but in the chip fuse of this embodiment, the chip is removed and wire bonded between the electrodes. Therefore, when manufacturing the chip fuse of this embodiment, it is possible to use the conventional automatic mounting machine as is.

” - In each example, the electrode material was Δg/[
) The conductor is not limited to the d-type conductor, but any material having the necessary heat resistance and soldering properties may be used, and thick film conductors, plated films, thin film conductors, and laminated films thereof can also be used.

The chip fuse of the present invention can be made much smaller than conventionally used fuses, so it can be easily incorporated into electrical components such as resistors and capacitors, and it can improve the safety of resistors with built-in fuses and capacitors with built-in fuses. It can also be used as an electrical component with

The present invention has been variously explained above using preferred embodiments, but the present invention is not limited to these embodiments.
Of course, many modifications can be made without departing from the spirit of the invention.

(9! Bright Effect) The chip fuse of the present invention, configured as described above, can be made much smaller than conventional fuses. This makes it easy to combine with various parts such as capacitors and resistors. Further, since the fuse effecting body is protected by an insulating heat-resistant substrate, it has high heat resistance and can be operated with solder dips, solder reflow, etc., and can be suitably used for surface mounting. This enables high-density mounting of electrical equipment.

In addition, when forming the fuse acting body by vacuum evaporation, the fusing characteristics of the fuse can be controlled as appropriate.
Further, the pattern forming the fuse effecting body can be arbitrarily designed.

Furthermore, chip fuses obtained by wire bonding metal wires can be easily manufactured by wire bonding, and conventional automatic bonding machines can be used.

Furthermore, the chip fuse of the present invention has the following advantages: the blowing characteristics of the fuse acting body can be appropriately controlled and set, and there is no variation in the blowing characteristics caused by the structure of conventional indirectly operated fuses. Effective.

[Brief explanation of drawings]

FIGS. 1(a) and (b) are side sectional views and plan views showing a first embodiment of a chip fuse according to the present invention, and FIGS. 2(a) and (b) are side views showing a second embodiment. Sectional View and Plan View, FIGS. 3(1) and (1)) are a side sectional view and a plan view showing the third embodiment. DESCRIPTION OF SYMBOLS 1... Substrate, 2... Electrode, 2a... Connection part,
3.5...Fuse action body, 4...Insulation protector. Figure Figure Figure

Claims (1)

[Claims] 1. A chip fuse characterized in that electrodes are provided on an insulating heat-resistant substrate such as ceramics, and the electrodes are connected by a fuse acting body. 2. The fuse acting body is provided as a metal thin film layer obtained by depositing a metal having predetermined fusing characteristics between the electrodes by vacuum evaporation on an insulating heat-resistant substrate on which electrodes are formed. The chip fuse according to claim 1. 3. A metal wire having a predetermined fusing characteristic is used as the fuse acting body, and the metal wire is wire-bonded between electrodes of an insulating heat-resistant substrate on which electrodes are formed. chip fuse.