JP2000049001A - Resistor for surge protection - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain a resistor for surge protection in which surge currents hardly concentrate on the folded part of a resistor film and which can obtain stable characteristics. SOLUTION: A resistor for surge protection is constituted by arranging a plurality of linear resistor patterns 2a, 2b, etc., in parallel on a substrate 1 and connecting members among patterns 2a, 2b, etc., so as to connect adjacent resistor patterns 2a, 2b, etc., in series. At least the connecting regions (x) between the patterns 2a, 2b, etc.,, and the connecting members are made of a conductive material which is composed mainly of Ag or Cu.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a resistor element, and more particularly to a structure of a resistor pattern for surge protection.

[0002]

2. Description of the Related Art In a conventional surge protection resistor, a resistor film having a predetermined resistance value is formed by baking a resistor paste made of ruthenium oxide or the like on an insulating substrate such as alumina. Also, for example, on an insulating substrate,
A resistor film having a predetermined shape is formed by a sputtering method or the like while covering a predetermined mask.

[0003] A resistor for surge protection is formed of a metal material having a relatively high conductivity, and is formed in a long current path pattern (a resistor film having a long conductor length) in order to obtain a high resistance.

In order to form such a resistor film having a long conductor length, a resistor film 51 having a serpentine folded pattern is conventionally formed on the surface of an insulating substrate 50 as shown in FIG. In addition, between both ends and the insulating substrate 50,
Alternatively, electrode pads 52 and 53 made of a conductive film having good conductivity are formed on the upper surfaces of both end portions as shown by oblique lines.
As shown in FIGS. 5 and 6 (a), in order to control the resistor film in the region of the predetermined substrate 50, the zigzag folded portion R is bent in a substantially U-shape or as shown in FIG. 6 (b). For example, a pattern in which the bent portion R is bent in a substantially U-shape is used.

Usually, as shown in FIGS. 5 and 6 (a), the bent portion R is formed to be curved at a predetermined curvature. This is because when a surge current flows through the resistor film 51, the current is expected to flow relatively uniformly over the entire conductor width.
That is, as shown in FIG. 6B, when the bent portion R is bent at 90 °, a surge current is concentrated inside the conductor film, and a part of the resistor film 51 is easily burned. In FIG. 6, the direction of the current is indicated by an arrow. That is, in FIG. 6A, in the structure in which the bent portion R is curved at a predetermined curvature, there is no extreme difference between the inner periphery and the outer periphery of the resistor film. On the other hand, as shown in FIG. 6B, in the structure bent at right angles, current is concentrated inside the bent portion R. It is thought that destruction will progress from here.

On the other hand, in order to improve the mounting density of the insulating substrate, as shown in FIG. 6B, the bent portion R is bent at 90 ° to reduce the distance between the adjacent resistor films 51. It is effective. However, when the above-described current concentration is considered, it should be practically avoided.

[0007]

At the bent portion R of the conventional surge protection resistor film, if the curvature is not sufficiently large, current concentration occurs on the inner peripheral side, and the film is easily damaged. Therefore, as a result of the pattern of the resistor film, in particular, a serpentine shape, it is not possible to form the gap between the adjacent resistor films, and the occupied area on the insulating substrate becomes very large. As a result, the board mounting density could not be increased.

In order to increase the mounting density, a structure in which bending is repeated at 90 degrees is conceivable. In this case, however, current concentration cannot be avoided, and it cannot be applied to a surge protection resistor.

SUMMARY OF THE INVENTION The present invention has been made in view of the above problems, and has as its object to form a resistor film substantially 90 °.
It is an object of the present invention to provide a surge protection resistor in which a surge current hardly concentrates on a bent portion even if the bent portion is bent.

[0010]

According to a first aspect of the present invention, a plurality of linear resistor patterns are provided on a substrate,
A surge protection resistor in which each resistor pattern is connected in series by a connection member, wherein the connection member is made of Ag
Alternatively, the surge protection resistor is made of a conductor material containing Cu as a main component.

According to a second aspect of the present invention, there is provided a surge protection resistor comprising a plurality of linear resistor patterns arranged on a substrate and connecting the respective resistor patterns in series by connecting members. A surge protection resistor characterized in that an intermediate conductor film containing Ag or Cu as a main component is applied to a surface region of the resistor pattern to which the connection member is connected.

[0012]

According to the present invention, a plurality of resistor patterns constituting a resistor film are linearly juxtaposed and connected in series with each other so as to have a predetermined conductor length. This connection is achieved by a connecting member.

In the first invention, the connecting member is made of Ag or C
It is made of a conductor material mainly containing u. Further, in the second invention, the surface where the resistor pattern and the connection member are connected is covered with the intermediate conductor film mainly composed of Ag or Cu. That is, a conductive film containing Ag or Cu as a main component is formed in a connection region where each resistor pattern is connected in series.

As a result, the surge current has conventionally been concentrated inside the bent portion. However, in the present invention, the surge current flows through the conductive film of good conductivity in the series connection region, so that the current Specifically, the current can be prevented from being concentrated on the bent portion.

Thus, a stable characteristic can be derived without a surge current being concentrated and sparking. In addition, since the resistor film is provided with a substantially linear resistor pattern, the substrate mounting density can be increased.

[0016]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A surge protection resistor according to the present invention will be described below with reference to the drawings.

FIG. 1 is a plan view of a surge protection resistor according to the first invention.

In the figure, 1 is an insulating substrate, 2 is a resistor pattern, 3a, 3b, 3c and 3d are connection members, and 4a and 4b are electrode pads. In particular, of the resistor pattern 2, 2a, 2b, 2c, 2d, 2e,
2f is provided with a reference numeral for convenience in detail to explain the adjacent relationship. In the figure, various surface wirings and electronic components constituting other circuits are mounted on the insulating substrate 1, but they are omitted in the figure.

The insulating substrate 1 is a heat-resistant substrate such as an alumina substrate. On the insulating substrate 1, for example, 5
Book linear resistor patterns 2a, 2b, 2c, 2d,
2e are formed to be parallel to each other. Specifically, it is formed by printing and baking a resistance paste such as ruthenium oxide.

Each of the resistor patterns 2a, 2b, 2c, 2
At the ends of d and 2e, connecting members 3 indicated by hatched portions in FIG.
a, 3b, 3c, and 3d are arranged. Connection member 3
a, 3b, 3c, and 3d are formed by printing and baking a conductive metal paste such as Ag, Ag-Pd, or Cu.

An electrode pad 4a is provided at one end (lower end in the figure) of the resistor pattern 2a.
An electrode pad 4a is formed at the other end (upper end in the figure) of e.

Here, the connection member 3a is formed so as to straddle the other end (the upper end in the figure) of the resistor pattern 2a and the other end (the upper end in the figure) of the resistor pattern 2b. The connection member 3b is formed so as to straddle one end (lower end in the figure) of the resistor pattern 2b and one end (lower end in the figure) of the resistor pattern 2c. Similarly, connection member 3
c, 3d are formed.

Thus, the electrode pad 4a, the resistor pattern 2a, the connection member 3a, the resistor pattern 2b, the connection member 3b, the resistor pattern 2c, the connection member 3c, the resistor pattern 2d, the connection member 3d, and the resistor pattern 2e A series of surge resistors of the electrode pad 4b is formed.

The resistance of the connection members 3a to 3d is infinitely close to zero and substantially negligible as compared with the resistance patterns 2a, 2b, 2c, 2d and 2e.
3d, the resistance patterns 2a, 2b
There is no potential difference in the width direction of b, 2c, 2d, and 2e, and the surge current in the resistor patterns 2a, 2b, 2c, 2d, and 2e can flow evenly. That is, the current distribution is as shown in FIG. FIG. 7 shows only the portions of the resistor patterns 2a and 2b and the connecting member 3a which are adjacent to each other.

The resistor patterns 2a, 2b, 2c,
Since 2d and 2e are linear and are provided side by side, the resistor patterns 2a, 2b, 2
The interval between c, 2d, and 2e adjacent to each other can be reduced, and the mounting density on the surface of the substrate 1 is improved.

The connection members 3a to 3d, the electrode pads 4
It is more advantageous for a and 4b to be thicker, and it is desirable to form them by a thick film technique. For example, the thickness is preferably about 5 to 20 μm.

The connection members 3a to 3d, the electrode pads 4
If a and 4b are thick, the resistor patterns 2a and 2b
After the formation of b, 2c, 2d, and 2e, they must be formed so as to overlap the upper surfaces of the resistor patterns 2a, 2b, 2c, 2d, and 2e.

This is because the resistor patterns 2a, 2b, 2
This is to prevent disconnection due to a step at the boundary between the connection members c, 2d, and 2e and the connection members 3a to 3d.

The resistor patterns 2a, 2b, 2c, 2
d, 2e and the connecting members 3a to 3d may employ various methods such as thermal spraying and sputtering other than the thick film printing method.

FIG. 2 is a modification of FIG. 1 and is a plan view of a surge protection resistor according to the second invention.

In this example, the connection member is a resistor pattern 2
a, 2b, 2c, 2d, and 2e are formed of the same material and in the same process. Note that the reference numerals 21a, 21
b, 21c and 21d.

An important structure in FIG. 2 is that, for example, in two adjacent resistor patterns 2a and 2b, the other ends of both resistor patterns 2a and 2b are integrated with a connection member 21a made of a resistive material. ing. Then, a bent portion X between the resistor pattern 2a and the connecting member 21a (shown by oblique lines in the drawing).
An intermediate conductor film 31a whose main component is a conductor material such as Ag, Ag-Pd, or Cu is superposed thereon. An intermediate conductor film 32a mainly composed of a conductor material such as Ag, Ag-Pd, or Cu is superimposed on a bent portion X (shown by oblique lines in the drawing) between the resistor pattern 2b and the connection member 21a. I have.

The other connecting members are the resistor pattern 2
The same applies to 1b, 21c, 21d, and the intermediate conductor films 31b, 32b, 31c, 32 are provided at the bent portion X, which is a portion connected in series with the resistor patterns 2b, 2c, 2d, 2e.
c, 31d and 32d are formed in an overlapping manner.

The configuration shown in FIG. 2 is used when the distance between the adjacent resistor patterns 2a, 2b, 2c, 2d, and 2e is large, or when the resistor patterns 2a, 2b, 2c, 2d, and 2e are used.
This is useful when e has a spiral shape.

FIG. 3 is for adjusting the resistance value of the surge resistor 2. Generally, to adjust the resistance value, a part of the resistor film was irradiated with laser.

FIG. 3 shows the resistor patterns 2a, 2b, 2
After forming c, 2d and 2e, the resistor patterns 2a and 2e
b, 2c, and 2d, a common conductor film 5 containing Ag or Cu as a main component is formed at the other end.
A common conductor film 6 containing Ag or Cu as a main component is formed at one end of b and 2c, and a connecting member 3d is formed at one end of the resistor patterns 2d and 2e.

What is important here is that, when the resistance value of the surge resistor is adjusted to increase, the laser irradiation or the like is performed at the interval between the resistor patterns 2a, 2b, 2c, 2d of the common conductor films 5, 6. The common conductor films 5 and 6 are cut over the entire conductor width.

For example, in the drawing, before forming the cutting groove, the actual resistance value of the surge resistor is the resistor patterns 2d and 2e.

It is assumed that the common conductor film 5 forms the resistor pattern 2
When the cut groove C1 is formed at the interval between the c and 2d, the actual resistance value of the surge resistor becomes the resistor pattern 2
d, 2e, and 2c. Further, when the cut groove C2 is formed in the common conductor film 6 at the space between the resistor patterns 2a and 2b, all the resistor patterns 2a, 2b, 2c,
d and 2e are actual resistance values of the surge resistor.

As described above, the linear resistor pattern 2
As shown in FIG. 3, if the common conductor films 5 and 6 are provided at the serially connected portions a, 2b, 2c, 2d and 2e, the resistance value can be easily adjusted to increase.

FIG. 4 shows a case where the adjustment is performed in a direction to lower the resistance value of the surge resistor 2.

This can be achieved by adding resistance value adjusting conductor films J1 and J2 between adjacent connection members, for example, based on the surge protection resistor shown in FIG.

In FIG. 4, the conductor film J1 for resistance value adjustment is used.
Is added between the electrode pad 4a of the resistor pattern 2a and the connection conductor film 3b formed between the resistor patterns 2b and 2c, the actual resistance value of the surge resistor becomes the resistor pattern 2d, 2e, and 2c. further,
Connecting the resistance adjusting conductor film J2 to the connection member a and the connection member 3
When the resistance value is added between c and c, the actual resistance value of the surge resistor becomes the resistor patterns 2d and 2e. The conductor films J1 and J2 for adjusting the resistance value are formed by applying and curing at predetermined positions using a conductive paste having a conductive powder such as Ag powder.

As described above, using the surge protection resistor shown in FIG. 1 as a basic structure, as shown in FIG. 4, the resistance value can be easily reduced and adjusted, and the versatility is improved. In addition, since the potentials can be equalized by the connection members 3a to 3d in advance, the structure is such that the current is not concentrated by the connection using the conductive material.

In the above embodiment, the description has been made on the assumption that the surge protection resistor is formed on a part of the circuit board constituting another circuit on the insulating board. Even if only the resistor is formed on a small insulating substrate, a small-sized component can be obtained.

[0046]

As described above, even if the resistor film is bent substantially at 90 °, a surge current can be uniformly flowed at the bent portion (serial connection portion), and the surge current is prevented from being concentrated. And a surge protection resistor that is not easily destroyed.

Further, since the resistor patterns can be formed close to each other, a high-density pattern can be formed in a small area.

[Brief description of the drawings]

FIG. 1 is a plan view of a surge protection resistor according to a first invention.

FIG. 2 is a plan view of a surge protection resistor according to a second invention.

FIG. 3 is a plan view of another surge protection resistor according to the first invention.

FIG. 4 is a plan view of still another surge protection resistor according to the first invention.

FIG. 5 is a plan view of a conventional surge protection resistor.

FIGS. 6A and 6B are schematic diagrams illustrating the flow of current in a resistor film due to a difference in a bent portion. FIGS.

FIG. 7 is a schematic diagram illustrating a current flow at a bent portion in the present invention.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 ... Insulated area plate 2 ... Resistor film 2a, 2b, 2c, 2d, 2e ... Resistor pattern 21a-21d, 3a-3d ... Connection member 4a, 4b ... Electrode pad

Claims (2)

[Claims] 1. A surge protection resistor in which a plurality of linear resistor patterns are provided on a substrate and each resistor pattern is connected in series by a connection member, wherein the connection member is A surge protection resistor comprising a conductor material mainly composed of Ag or Cu. 2. A surge protection resistor comprising a plurality of linear resistor patterns provided side by side on a substrate, and each resistor pattern connected in series by a connecting member, wherein A surge protection resistor, wherein an intermediate conductor film containing Ag or Cu as a main component is applied to a surface region to which the connection member is connected.