JP2627650B2 - Flat type resistor and its lead terminal bonding - Google Patents

Description

Description: BACKGROUND OF THE INVENTION (Industrial Application Field) The present invention relates to a flat-type resistor and a method for joining lead terminals thereof, and more particularly to a flat-plate with a high-power lead wire in which a large pulsed current flows momentarily. TECHNICAL FIELD The present invention relates to a joining structure and a joining method between an electric conductor part of a type resistor and a lead wire.

(Prior Art) Conventionally, as a flat resistor for large power, a thin film resistor 22 is adhered to the surface of a heat conductive substrate 21 having excellent electrical insulation such as an alumina substrate as shown in FIG. Then, elongated electric conductors 23 and 23 ′ are adhered in parallel along opposing edges on the surface of the thin film resistor 2, and a multi-core lead wire 24 is attached to a substantially central portion in the longitudinal direction of the conductor. One with a 24 'is known. The high-power flat-plate resistor is fixed to the surface of a hollow box having a water-cooled structure, for example, and is used as a water-cooled resistor in a thyristor inverter as a high-power power supply such as an induction heating power supply. .

(Problems to be Solved by the Invention) In a conventional flat-type resistor, when a large current is applied, partial current concentration occurs on the entire joint portion between the electrode conductor portion and the resistor, and the resistive film deteriorates from that portion. Starts, and there is a problem that durability is reduced. It is considered that the cause is that the current path from the lead wire to the resistor via the electrode conductor is not uniform in the electrode conductor due to the area resistance of the electrode conductor. Therefore, in order to solve the problem, it is sufficient to reduce the sheet resistance of the electrode conductor, but the electrode conductor must be elongated to effectively use the resistance surface, and the thickness is increased. For this reason, it is difficult to reduce the sheet resistance of the electrode conductor part because, for example, it is difficult to increase the thickness because the productivity is reduced and the cost is increased. On the other hand, as a measure for solving the above-mentioned problem without reducing the sheet resistance of the electrode conductor portion, as shown in FIG. 5, the multi-core lead wire 25 extends over substantially the entire length of the electrode conductor portion 26 in the longitudinal direction. It is conceivable to make the current density of the electrode conductor portion uniform by soldering to the electrode conductor and flowing a current directly from the lead wire over the entire length of the electrode conductor. But,
Even in the case of this method, when the multi-core lead wire 25 and the electrode conductor 26 are soldered, as shown in FIG. As a result, the current distribution in the electrode conductor is not uniform,
The above problem cannot be completely eliminated. In the figure, 28
Is a flat resistor.

Another problem with the conventional flat-plate resistor with multi-core leads is that the lead wires are connected to the electrode conductors by soldering, which results in low mechanical strength.

The present invention has been made in view of the above circumstances,
The purpose is to eliminate the non-uniformity of the current distribution between the electrode conductor and the resistor without increasing the thickness of the electrode conductor of the flat-plate resistor, A flat plate resistor having a lead terminal structure capable of preventing the electrode conductor portion and the resistor near the electrode from deteriorating, improving the mechanical strength of the lead terminal portion, and improving the durability of the flat plate resistor, and a lead thereof. It is to provide a terminal joining method.

(Means for Solving the Problems) A flat resistor according to the present invention for achieving the above object,
In a flat plate type resistor with a lead wire formed by joining a flat electrode conductor portion formed on the surface of a flat resistor and a lead wire to form a current path, a metal around which the core wire of the lead wire is wound The present invention employs a technical means having a lead terminal structure including a piece and a flat electric conductor portion in which the core wire and the metal piece are joined together.

The lead terminal bonding method for obtaining the flat plate resistor employs a technical means characterized in that the core wire of the lead wire is wound around a metal piece and then bonded to a flat electric conductor portion. Things.

(Operation) The above-described lead terminal structure reduces the contact resistance from the lead wire to the resistive film, and allows current to flow uniformly from the lead wire and the electrically good conductive metal piece to the electrode conductor, and from the lead wire to the electrode conductor. Current distribution can be made uniform. As a result, the current distribution from the electrode conductor to the resistance film becomes uniform. As a result, a micro temperature rise due to partial current concentration can be avoided, and the durability of the lead type flat plate resistor can be greatly improved and the failure rate can be significantly reduced.

In addition, due to the above terminal structure, the joining strength between the electrode conductor and the lead wire is greatly improved as compared with the conventional soldering of the lead wire to the electrode conductor, and a mechanically strong resistor is obtained. Can be

Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.

FIG. 1 is a perspective view of an essential part showing one embodiment of a lead terminal structure of a flat plate type resistor with lead wires according to the present invention.

In the figure, reference numeral 1 denotes an insulating substrate made of a plate-like insulating ceramic having excellent electrical insulation and thermal conductivity, such as an alumina substrate.
Is a thin film resistor formed in a fixed area and a fixed shape on the surface of the insulating substrate by a suitable film forming method such as a vacuum electrodeposition method, a screen printing baking method, and a foil body bonding method. It is a pair of electrode conductors formed in parallel along opposing edges on the surface of the thin film resistor 2 by a film forming method (only one is shown in the figure).

Reference numeral 4 denotes a multi-core lead wire. In the present embodiment, the multi-core lead wire 4 is divided into two bundles 5, 5 ', and the length is substantially equal to the length of the electrode conductor portion in the longitudinal direction. As shown in the figure, around the metal side 6 consisting of a round wire of a good electrical conductor such as a hard copper wire cut into a length, the lead wire is wound hard so that the divided portion is located at the center. The lead terminal was formed by soldering the wire and the metal piece together to the electrode conductor portion 3. Although only one electrode is shown in the drawing, another lead terminal having the same structure is provided on the other electrode conductor.

FIG. 2 shows another embodiment of the present invention, in which a metal piece 9 made of a copper prism material having a trapezoidal cross section or the like is used as the metal piece. Other configurations are the same as those of the above-described embodiment, and are denoted by the same reference numerals.

As in the above two embodiments, the multi-core lead wire is divided into a plurality of portions, and the divided portion is located at the central portion in the length direction of the electrode conductor portion, and is extended on both sides from there. It is desirable to make the current density uniform, but the present invention is not necessarily limited to this. It may be configured by soldering so as to extend in one direction.

FIG. 3 shows still another embodiment of the present invention. In the present embodiment, a disk-shaped thin film resistor 11 is formed on the surface of an insulating substrate 10 such as an alumina substrate by an appropriate film forming method as described above. A narrow donut-shaped electrode conductor portion 12 is formed, and the other electrode 13 is formed at the center. The multi-core lead wire 14 joined to the outer peripheral electrode conductor 12 is divided into two core bundles 15 and 15 ′, each of which is a ring-shaped hard copper wire metal having substantially the same radius as the electrode conductor 12. A piece 16 is hard-wound and soldered to the surface of the electrode conductor 12 at the outer periphery. The multi-core lead wire of the other pole is soldered to the center.

In the present embodiment, the metal pieces need not be ring-shaped, but may be two semicircular arc-shaped pieces. Alternatively, two arc-shaped electrode conductors may be provided on the outer periphery of the resistor, and each lead terminal formed by winding a multi-core lead wire around an arc-shaped metal piece may be soldered.

As described above, various embodiments of the lead terminal structure of the flat plate resistor according to the present invention have been described. However, the present invention is not limited to these embodiments. The joining is not limited to soldering, and other joining methods such as welding can be adopted, and various design changes can be made within the scope described in the claims. These resistors are excellent for high power, for example, when the insulating substrate is fixedly attached to the surface of a box body through which cooling water circulates in the body cavity, the heat generation of the resistor is effectively suppressed. A water-cooled resistor can be obtained.

Next, the results of a comparative test performed on a flat-type resistor according to the present invention in which the lead terminal structure was manufactured according to the first embodiment, and as a comparative example, a lead-type resistor having the lead terminal structure shown in FIG. 5 were shown. .

A 35 mm × 10 mm resistor is formed on a 40 mm × 21 mm alumina substrate by a thick film firing method, and 30 mm is placed near both sides of the surface of the resistor.
A flat resistor with a resistance value of 10 ohms, with a 3 mm electrode conductor formed by the thick-film firing method, is used to make a 30-mm long steel-copper metal piece with a multi-core lead consisting of 30 cores with a core diameter of 0.15 mm. First
It was wound as shown in the figure and soldered to the electrode conductor. In the case of the comparative example, a similar multi-core lead wire was directly soldered to the electrode conductor as shown in FIG.

In both cases, the peak voltage is varied to make the pulse width 3
μs, a pulse voltage with a pulse repetition frequency of 10 KHz was applied, the pulse voltage was 100 V to 200 V, that is, the pulse current was 10 A
At about 20 A, there was no abnormality in both, but pulse voltage 400
In V, no abnormality occurred in the former planar resistor according to the embodiment of the present invention, but in the latter flat resistor having the lead terminal structure of FIG. From the seam and burnt out. In the former, no abnormality was observed even at a pulse voltage of 500 V, that is, a pulse current of 50 A, and it was found that the flat type resistor having the terminal structure according to the present invention maintained good performance. In the above experiment, it goes without saying that coolers of the same performance were attached to the back surface of the alumina substrate to prevent steady heating of the resistor.

(Effect) The lead terminal structure of the flat-plate resistor of the present invention having the above-described configuration reduces the junction resistance from the lead wire to the resistive film in the flat-type high-power resistor handling a large current. At the same time, from the lead wire to the electrode conductor,
The current distribution from the electrode conductor to the resistor can be made uniform, and a micro temperature rise due to partial current concentration can be avoided, resulting in a significant improvement in durability and a reduction in failure rate. be able to.

In addition, since the core of the lead wire is attached to the metal piece and then joined to the flat electric conductor, joining is easy,
In addition, the present invention has excellent effects, for example, the joining strength is greatly increased as compared with the conventional one, the mechanical strength is high, and the maintenance and inspection can be reduced.

[Brief description of the drawings]

1 is a perspective view of a main part of a first embodiment of the present invention, FIG. 2 is a perspective view of a main part of a second embodiment, FIG. 3 is a perspective view of a third embodiment,
FIG. 4 is a perspective view showing a terminal structure of a conventional flat-type resistor,
FIG. 5 is a perspective view of a terminal structure of a flat plate type resistor showing a comparative example of the present invention, and FIG. 6 is a side view of a main part showing a defect thereof. 1, 10, 21: insulating plate, 2, 11, 22, 28: resistor, 3, 1
2, 23, 26: electrode conductor part, 4, 14, 24: multi-core lead wire,
5, 5 ', 15, 15': core bundle, 6, 9, 16: metal piece

Claims (2)

(57) [Claims] 1. A flat-plate type resistor with a lead wire, wherein a current path is formed by joining a flat electrode conductor portion formed on the surface of a flat resistor and a lead wire. A flat resistor having a lead terminal structure including a metal piece wound with a core wire and a flat electric conductor portion formed by joining the core wire and the metal piece together. 2. A method of joining lead terminals in a plate-type resistor having a lead wire, wherein a current path is formed by joining a plate-like electrode conductor portion formed on the surface of a plate-like resistor and a lead wire. And a method of bonding a lead terminal of a flat-type resistor, comprising winding a core wire of the lead wire around a metal piece and then bonding the core wire to a flat electric conductor portion.