JPH0526721Y2 - - Google Patents

Description

[Detailed description of the invention] [Purpose of the invention] (Field of industrial application) The present invention relates to a fixed resistor with a lead wire, and more particularly to a resistive film.

(Prior Art) Conventionally, the coating of a fixed resistor with a lead wire (for example, a metal glaze film fixed resistor, etc.) has been formed by a method such as dipping a metal glaze member into the curved surface of a cylindrical ceramic. ing. However, this method has a problem in that the coating is uneven and it is difficult to obtain a uniform film, making it difficult to improve the production efficiency of the film deposition process.

[Problems to be solved by the invention] In view of the above-mentioned problems, the present invention eliminates unevenness in the resistive coating and makes it possible to obtain a uniform film.
It aims to improve production efficiency or productivity.

[Structure of the invention] (Means for solving the problems) The present invention includes a flat chip ceramic substrate having a substantially hexahedral shape, a resistive film, an electrode electrically connected to at least the resistive film, and A metal electrode cap fitted onto the electrode so as to be electrically connected to the electrode, a lead wire attached to an outer end surface of the electrode cap, and at least the resistive film, the exposed electrode portion, and the electrode cap. At least a component thereof is an insulating coating film that covers a part of the lead wire.

(Function) In the present invention, as the ceramic substrate of the fixed resistor with lead wires, a flat chip type made of, for example, a flat plate or a substantially hexahedron including a square shape is used to form a resistive coating, so there is no unevenness. A highly uniform film can be obtained at the same level as film formation.

(Example) An example of the present invention will be described with reference to the accompanying drawings. 1 in FIG. 1 is a resistive film uniformly coated on a flat-chip ceramic substrate made of a substantially rectangular parallelepiped and heated and fired. Electrodes 2, 2 are formed at both ends in the length direction, and metal electrode caps 3, 3 are fitted, for example, to cover the electrodes 2, 2 and to be electrically connected to the electrodes 2, 2. For example, lead wires 4, 4 are welded to approximately the center of the outer end surfaces of the electrode caps 3, 3. Here, lead wires 4, 4 are welded in advance to approximately the center of the outer end surfaces of the electrode caps 3, 3.
It may be fitted into the

Furthermore, except for a portion of the lead wires 4, 4, the ceramic substrate, the resistive film 1, the exposed portions of the electrodes 2, 2, and the entirety of the electrode caps 3, 3 are printed using a printer and a firing furnace (not shown), respectively. An insulating coating film 5 is applied and heated and baked. Here, the insulating coating film 5 is made of, for example, epoxy resin.

In this way, the fixed resistor with lead wire of the present invention is manufactured. The shape of the electrode caps 3, 3 is not limited to the substantially rectangular tray shape shown in FIG. 1, but may be, for example, substantially circular tray shape.

Further, the shape of the fixed resistor with a lead wire of the present invention is not limited to the substantially rectangular parallelepiped shown in FIG. 1, but may be any other substantially hexahedral shape. in this way,
By making the shape of the surface on which the resistive film 1 is formed on the ceramic substrate at least a flat surface or a smooth surface (for example, a flat plate or a square shape) (rather than having a curved side surface such as a columnar shape), As a film method, a simple method such as screw printing means can be used, and a uniform resistive film can be obtained. Since the screen printing means can control the thickness of the resistive material, for example, by controlling the emulsion thickness of the screen, the level or degree of film formation of the resistive film 1 is increased, and unevenness is eliminated.

For this reason, the defect rate during trimming (not shown: adjustment to the target resistance value) after the resistive film 1 is printed and formed by heating and baking is reduced, which greatly contributes to production efficiency or productivity and film deposition cost reduction. .
For example, while the trimming failure rate of conventional cylindrical resistors (not shown) using a laser trimming device (not shown) after resistive film formation is 2.0%, the flat chip resistor of the present invention (for example, flat or square) has a trimming failure rate of 2.0%. Shape) The trimming failure rate after forming a resistive film on a ceramic substrate is 0.07%.
This is an improvement of about 29 times.

[Effects of the invention] As explained above, according to the invention, the shape of the resistive film forming surface on the ceramic substrate of the fixed resistor with lead wires is flat or smooth,
For example, since the resistive film is formed using a flat chip made of a substantially hexahedron including a flat plate shape or a square shape, the level of film formation is high and unevenness is eliminated. Furthermore, since the trimming failure rate after forming the resistive film is reduced, production efficiency or productivity is improved, leading to cost reductions in forming the resistive film and in the fixed resistor with lead wires.

[Brief explanation of drawings]

FIG. 1a is a perspective view of a fixed resistor with lead wires showing an embodiment of the present invention, FIG. 1b is a partially transparent perspective view showing a state in which electrode caps are fitted to both electrodes in FIG. 1a, Figure 1c is a perspective view showing the state in which lead wires are connected to both outer end surfaces of the electrode cap shown in Figure 1b, and Figure 1d is a perspective view showing that almost the entire fixed resistor is insulated except for a portion of the lead wires shown in Figure 1c. FIG. 3 is a perspective view showing a state in which a coating film is applied. 1... Resistive film, 2... Electrode, 3... Electrode cap, 4... Lead wire, 5... Insulating coating film.

Claims (1)

[Scope of utility model registration request] A flat-chip ceramic substrate having a substantially hexahedral shape, a resistive film, an electrode electrically connected to at least the resistive film, and a metal plate fitted onto the electrode so as to be electrically connected to the electrode. At least the constituent elements include an electrode cap, a lead wire attached to an outer end surface of the electrode cap, and an insulating coating film covering at least the resistive film, the electrode exposed portion, and a part of the electrode cap and the lead wire. A fixed resistor with lead wires featuring: