JPH11214239A - Surface mount electric component - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain highly stable dielectric SMT components which do not allow any piezoelectric effect to be generated. SOLUTION: The main body 1 of an electric components made of a dielectric substance and strip lead electrodes 2 connected to the main body 1 are molded with a resin 4 and external electrodes for surface mounting are formed by bending the electrodes 2 to the lower surface of the molding resin 4 along the side faces of the resin 4. The side faces 4a of the molding resin 4 are inclined inward so that prescribed spaces 6 may be formed respectively between the side faces 4a and the vertical sections of the electrodes 2 and, at the same time, the electrodes 2 are formed to have narrow-width sections 3 which contain the boundaries between the resin 4 and the electrodes 2 coming out from the resin 4. When such SMT components are mounted on a printed wiring board 7, the molding resin 4 isolates the electrodes 2 from the main body 1 by maintaining the shape of the main body 1 and the narrow-width sections 3 and the spaces 6 between the inclined side faces 4a and lead electrodes 2 absorb mechanical pressures produced by the thermal expansion, shrinkage, etc., of the wiring board 7 resulting from soldering 5.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an electric component for surface mounting (hereinafter, SMT component), and more particularly to an SMT component mainly composed of a dielectric component.

[0002]

2. Description of the Related Art In an example of an SMT component according to the prior art shown in FIG. 3, an electrode is provided on a component body of a surface mount electrical component 11, and soldering 5 is directly performed on a conductor pattern 8 on a printed wiring board 7. Therefore, a mechanical pressure change such as thermal expansion of the printed wiring board 7 is directly applied to the chip component body, and the piezoelectric effect is easily generated.

[0003] As a method expected to be effective against such a problem, an SMT disclosed in Japanese Utility Model Laid-Open No. 60218/1990 is known.
A method in which a lead is wound around a component body electrode to form a stress buffering material, and a flexible board disclosed in Japanese Utility Model Laid-Open No. 6-9169 is mounted between one electrode of an SMT component and a printed wiring board. Methods, etc. have been devised.

[0004]

When a circuit having an SMT component mainly composed of a dielectric component according to the prior art is exposed to a temperature change, an instantaneous signal voltage change may occur, and an oscillator or a frequency may be generated. There is a problem that it is difficult to use it in an electric circuit requiring high stability such as a control circuit.

[0005] The reason is that the SMT component according to the prior art has electrodes on the component body and is directly soldered to the printed wiring board, so that a mechanical pressure change such as thermal expansion of the printed wiring board is directly affected by the chip component. This is because a piezoelectric effect may be generated in addition to the main body.

To cope with such a problem, Japanese Unexamined Utility Model Publication No. Hei 2-60218 and Japanese Unexamined Utility Model Publication No. Hei 6-9169 have disclosed. However, the former is powerless except for the contraction of the printed wiring board in the electrode direction, and the latter is expected to concentrate mechanical movement on the soldered portion, and has a problem in durability.

It is an object of the present invention to firstly provide an SMT component having high stability which does not generate a piezoelectric effect, and secondly, it is possible to realize the first object more easily. The goal is to provide a highly reliable method.

[0008]

According to a first aspect of the present invention, there is provided a surface-mounting electrical component to be mounted on a printed circuit board, wherein a strip-shaped lead electrode is connected to the component body, and the component body and the strip-shaped electrode are connected to each other. Perform resin molding on the connection part of the lead electrode, bend the strip-shaped lead electrode along the side surface of the resin mold to the lower surface of the resin mold to form an external electrode for surface mounting, and as the side surface of the resin mold goes down, A predetermined gap is provided between the vertical portion of the strip-shaped lead electrode and the vertical portion of the strip-shaped lead electrode as if tapering inward, and the lead width of a portion of the strip-shaped lead electrode including a boundary coming out of the resin mold is reduced. It is preferable to use a dielectric component for the component body.

More specifically, a strip-shaped lead electrode (FIG. 1-2) is connected to a component body (FIG. 1-1) mainly composed of a dielectric component, and the component body (1) and the strip-shaped lead electrode (2) are connected. The connection portion is resin-molded (FIG. 1-4), and the strip-shaped lead electrode (2) is bent along the side surface of the resin mold (4) to the lower surface of the resin mold (4) to be used as an external electrode for surface mounting as it is. . Here, an inclined surface (4a) is attached to the side surface of the resin mold (4), and the inner side is narrowed toward the bottom,
A predetermined gap (FIG. 1-6) is left between the vertical portion of the strip-shaped lead electrode (2) and the width of the strip-shaped lead at a portion including a boundary where the strip-shaped lead electrode (2) comes out of the resin mold (4). Has a narrow portion (FIG. 1-3).

In this way, when mounted on the printed wiring board (FIG. 2-7), the resin mold (4) retains the shape of the main body and the strip-shaped lead electrode (2) and the component main body (1) A printed wiring board (7) is formed by a narrow portion (3) of a strip-shaped lead having a reduced width and a gap (6) between a side surface of a resin mold (4) and a strip-shaped lead electrode (2).
Can absorb mechanical pressure such as thermal expansion and contraction.

[0011]

Next, the present invention will be described with reference to the drawings.

FIG. 1 is a plan view showing an embodiment of the present invention.
FIG. 2 is a sectional view, a bottom view, and a side view, and FIG. 2 is a sectional view showing an operation of this embodiment with respect to a mechanical change of the printed wiring board.

In FIG. 1 and FIG. 2, a band-shaped lead (band-shaped lead electrode) 2 is connected to a component main body 1 mainly composed of a dielectric component, and a resin mold 4 is applied to a connection portion between the component main body 1 and the band-shaped lead electrode 2. Then, the strip-shaped lead electrode 2 is bent along the side surface of the resin mold 4 to the lower surface of the resin mold 4 to form an external electrode for surface mounting on the printed wiring board 7 as it is. Here, the side surface of the resin mold 4 is inclined to form an inclined surface 4a which tapers inward as going downward, and the inclined surface 4a and the strip-shaped lead electrode 2 are formed.
A predetermined gap 6 is formed between the vertical portion and the vertical portion.
Further, the shape of the strip-shaped lead electrode 2 has a narrow portion 3 in which the width of the strip-shaped lead electrode 2 in a portion including the boundary from the resin mold 4 is reduced. When mounted on the printed wiring board 7 shown in FIG. 2, the resin mold 4 retains the shape of the main body and separates the band-shaped lead electrode 2 from the dielectric component main body 1 to reduce the width of the band-shaped lead. 3 and the gap 6 between the side surface of the resin mold 4 and the strip-shaped lead electrode 2, the mechanical movement 9 accompanying the mechanical pressure change such as the thermal expansion and contraction due to the soldering 5 of the printed wiring board 7 and the movement of the strip-shaped lead. Absorb by 10.

In the embodiment of the present invention, as shown in FIG. 1, a dielectric component is used as the component body 1, and a ceramic magnetic capacitor chip is used as an example of the dielectric component. In the operation of the embodiment according to the present invention shown in FIG.
A mechanical movement 9 accompanying a mechanical pressure change such as thermal expansion and contraction due to soldering 5 of the printed wiring board 7 is caused by a movement 10 of the strip-shaped lead caused by the narrow portion 3 of the strip-shaped lead electrode 2 via the conductor pattern 8. It is converted into a change in the gap 6 between the strip-shaped lead electrode 2 and the resin mold 4, so that no mechanical force is transmitted to the component body 1 of the ceramic magnetic capacitor chip in the resin mold 4.

Further, in another embodiment of the present invention, a plastic film capacitor may be used as the dielectric component.

[0016]

According to the SMT component of the present invention, when mounted on a printed wiring board, the resin mold retains the shape of the main body and separates the strip-shaped lead electrode from the component main body (mainly a dielectric component), and has a width. The mechanical pressure such as expansion and contraction of the printed circuit board is absorbed by the gap between the strip-shaped lead electrode and the inclined side of the resin mold where the narrow strip is formed. Therefore, no mechanical pressure is applied to the component body, which has the effect of not causing instantaneous signal voltage fluctuations due to the piezoelectric effect. Dielectric components are also used in electrical circuits such as oscillators and frequency control circuits that require high stability. SMT parts can be used.

[Brief description of the drawings]

FIG. 1 shows an embodiment of an SMT component of the present invention (a).
Is a plan view, (b) is a cross-sectional view, (c) is a bottom view, and (d) is a side view.

FIG. 2 is a cross-sectional view showing an operation of this embodiment with respect to a mechanical change of a printed wiring board.

FIG. 3 is a sectional view showing a conventional SMT component.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Component main body (ceramic ceramic capacitor chip) 2 Strip-shaped lead electrode 3 Narrow part 4 Resin mold 5 Soldering 6 Gap 7 Printed wiring board 8 Conductive pattern 9 Mechanical movement 10 Strip-shaped lead movement 11 Surface-mounted electrical parts

Claims (4)

[Claims] 1. An electrical component for surface mounting to be mounted on a printed wiring board, wherein a strip-shaped lead electrode is connected to a component body, and a resin molding is performed on a connection portion between the component body and the strip-shaped lead electrode. An electrode is bent along the side surface of the resin mold to the lower surface of the resin mold to form an external electrode for surface mounting, and the side surface of the resin mold is an inclined surface that slopes inward as going downward. A surface mounting electrical component, wherein a predetermined gap is provided between a vertical portion and a lead width of a portion of the strip-shaped lead electrode including a boundary from the resin mold, the lead width being reduced. 2. The electric component for surface mounting according to claim 1, wherein a dielectric component is used for the component main body. 3. The electric component for surface mounting according to claim 2, wherein said dielectric component is a ceramic porcelain capacitor. 4. The electrical component for surface mounting according to claim 2, wherein said dielectric component is a plastic film capacitor.