JPH0541522Y2 - - Google Patents

Description

[Detailed description of the invention] [Purpose of the invention] (Field of industrial application) The present invention relates to a power type resistor as a surface mount device.

(Prior art) Conventional power type resistors are relatively large, with lengths ranging from tens of millimeters to several tens of millimeters. The structure shown in was adopted. That is, a ceramic case body 1 with an open bottom is filled with an encapsulant (cement) 2, a terminal piece 3 is connected to the lead wire of the resistor body embedded in the encapsulant 2, and the terminal piece 3 is inserted into the case body 1. A pair of terminal pieces 3, 3 are inserted into through holes of a printed circuit board and fixed by soldering.

(Problem to be solved by the invention) In the conventional resistor structure as described above, the terminal piece protrudes from the bottom surface of the case body for a long time, making it unsuitable for mounting using automatic machines and making it difficult to save labor. It was hot.

In view of the above-mentioned problems, the purpose of the present invention is to provide a resistor that has a compact overall structure, a large contact area of electrode pieces, and can be easily and reliably surface-mounted on a printed circuit board using an automatic machine. .

[Structure of the idea]

(Means for Solving the Problems) The resistor of the present invention includes an electrically insulating case body having an opening on one side, an encapsulant filled in the case body, and the case embedded in the encapsulant. A resistor body that is housed in the body and has lead wires connected to both ends thereof protruding outward from both end face plates of the case body, and an electrode piece provided in the case body and connected to the lead wires of the resistor body. The case body has mounting ridges formed in the width direction at both ends of the bottom surface, and the electrode piece is in contact with the bottom surface of the case body, and the electrode piece is in contact with the lower surface of the mounting ridges formed on the case body. and a dovetail groove shape having a wide contact surface parallel to the contact surface, and rising portions that rise inward on both sides of the contact surface and are engaged with the protrusion, and is used for mounting the case body. The lead wire of the resistor body is connected to the rising portion of the electrode piece fitted on the protrusion, which is located on the end plate side.

(Function) When the resistor of the present invention is surface mounted on a printed circuit board, it is fixed by the wide contact surface of the electrode piece attached to the bottom surface of the case, so the contact area with the printed circuit board is wide and the connection is reliable. It also improves vibration resistance. In addition, the electrode piece is attached to the lower surface of the case body, and the contact surface is attached parallel to the lower surface of the case body, and lead wires bent along both end surfaces of the case body are connected to this electrode piece.
The lead wire does not particularly protrude from the case body, and the overall shape becomes a substantially rectangular parallelepiped, making it easy to insert into an automatic machine and increasing reliability of operation.

(Example) An example of the present invention will be described with reference to FIGS. 1 and 2.

4 is a rectangular case made of ceramic such as steatite, and has an opening 5 on one side in the width direction.
are formed, and grooves 7, 7 are cut from both ends of the opening 5 in the length direction toward the center of the end plates 6, 6 at both ends in the length direction, respectively.

Further, dovetail-shaped protrusions 10, 10 for attaching electrodes are tapered downward at both ends of the bottom plate 8 of the case body 4, and have planar enlarged surfaces 9, 9 on the lower surface. is formed over the entire length in the width direction, one inclined surface 11, 11 of each of these protrusions 10 projects outward from the lower part of the end plates 6, 6, respectively, and the other inclined surface 12, 12, They are formed by inclined grooves 14, 14 formed from the lower surface of the thick portions 13, 13 at both ends of the lower surface of the bottom plate 8.

Further, a central protrusion 15 for temporary fixing is formed at the center of the lower surface of the bottom plate 8 in the width direction and has the same height as the thick portion 13.

Next, reference numeral 16 denotes a main body of the wire-wound resistor, which is housed in the case body 4 and has lead wires 18, 18 projecting in the axial direction from the cap electrodes 17, 17 at both ends. It protrudes outward from the inner ends of 7,7. Further, a space around the resistor main body 16 in the case body 4 is filled with an encapsulant 19, and the opening 5 of the case body 4 is closed by the encapsulant 19.

Next, 20 is an electrode piece made of a metal plate made of iron, brass, phosphor bronze, etc. and whose surface is finished with solder plating, bent into a dovetail shape. The central part of the direction serves as a flat, wide contact surface 21 that comes into contact with the enlarged surface 9 of the dovetail-shaped protrusion 10, and both sides of this contact surface 21 are bent inward in an inclined shape and rise up. portions 22 and 23 are formed, and a pair of electrode pieces 20 formed in this way
are pushed in from one end of the dovetail-shaped protrusion 10 of the case body 4, so that the contact surface 9 is brought into contact with the lower surface of the enlarged surface 9 of the protrusion 10, and one of the rising portions 22 is pressed against the lower surface of the enlarged surface 9 of the protrusion 10. The electrode pieces 20 are fixed to the respective protrusions 10 by engaging on the inclined surface 11 and pushing the other rising portion 23 into the inclined groove 14 . Further, in the center of one rising portion 22 of the electrode piece 20 that is engaged on the inclined surface 11, a depression 24 is formed.
The engagement piece 25 that straddles the 4 is integrally formed under pressure,
The lead wire 18 drawn out from the cut groove 7 of the end plate 6 of the case body 4 is bent downward along the end plate 6,
The lower end is inserted into the recess 24 of the electrode piece 20 and connected to the engaging piece 25 by crimping or welding.

Next, a method of manufacturing the resistor of the above embodiment will be explained.

An encapsulant 19 such as Crystallite is injected into the case body 4 through the opening 5 using an injection device to approximately 1/2 of the width.

Next, insert the resistor body 16 into the case body 4 with the lead wires 18, 18 connected to the cap electrodes 17, 17 at both ends while causing the lead wires 18, 18 to protrude outward from the grooves 7, 7. The lead wires 18, 18 are bent downward along the end plates 6, 6, and the remaining space is filled with encapsulant 19, and the opening 5 is
is closed with filler 19.

Next, the electrode pieces 20, 20 are inserted into the dovetail groove-shaped protrusions 10, 10 on the bottom, respectively. Next, lead wires 18, 18
The lower ends of the electrode pieces 20, 20 on the inclined surfaces 11, 11
are inserted into the recesses 24, 24, and connected by crimping with the engaging pieces 25, 25 or by welding.

Next, the operation of the above embodiment will be explained.

When mounting on a printed circuit board, first, the temporary fixing protrusions 15 of the case body 4 are fixed on the printed circuit board with adhesive, and then the contact surfaces 21 of the electrode pieces 20 are attached to the printed circuit board by soldering. Fixed to. At this time, since the surface of the electrode piece 20 has been solder-plated in advance, the solderability is good. Further, in the electrode piece 20, one rising portion 22 is engaged with the inclined surface 11 of the protrusion 10, and the other rising portion 23 is pushed into the inclined groove 14 of the case body 4. is securely held. Further, since the electrode piece 20 has a large contact surface 21, the electrical connection is reliable and the vibration resistance is high.

Furthermore, the lead wire 18 is connected to both end face plates 6 of the case body 4.
The lead wire 1 is bent downward along the
8 does not protrude from the case body 4 and get in the way, and can be easily supplied to an automatic machine.

[Effects of the invention] According to the invention, since the mounting of the printed circuit board is made in contact with the contact surface having a large area of the dovetail-shaped electrode piece, the connection by soldering is reliable and the vibration resistance is also good. . Furthermore, since the lead wires do not protrude outward from the case body for a long time, it is advantageous for surface mounting using an automatic machine. Furthermore, since the opening of the case body is on the side surface and the case body is mounted on the printed circuit board through the bottom plate, the heat generated during energization is less conductive to the printed circuit board.

[Brief explanation of the drawing]

FIG. 1 is a partially cutaway perspective view of a resistor showing an embodiment of the present invention, FIG. 2 is a longitudinal sectional side view of the same, and FIG. 3 is a perspective view of a conventional resistor from below. 4... Case body, 5... Opening, 6... End plate, 8... Bottom plate, 10... Projection, 16... Resistor body, 18... Lead wire, 19... Encapsulant, 20
... Electrode piece, 21 ... Contact surface.

Claims (1)

[Claims for Utility Model Registration] An electrically insulating case body having an opening on one side, a mounting medium filled in the case body, and an electrically insulating case body that is embedded in the mounting medium and housed in the case body and connected to both ends. The resistor body includes a resistor body with lead wires protruding outward from both end face plates of the case body, and an electrode piece provided on the case body to which the lead wires of the resistor body are connected; Mounting ridges are formed in the width direction at both ends, and the electrode piece has a wide contact surface parallel to the bottom surface of the case body that comes into contact with the lower surface of the mounting ridges formed on the case body. , an electrode piece formed in a dovetail shape having both sides of this contact surface rising inward and having rising portions that are engaged with the protrusions, and fitted into the mounting protrusions of the case body; A resistor characterized in that a lead wire of the resistor body is connected to a rising portion located on an end plate side of the resistor.