JP2003218311A - Electronic part having lead wire - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an electronic part having a lead wire for being installed on a wiring pattern board, which enables the reliability of soldering the electronic part to be improved. <P>SOLUTION: The electronic part 2 has a lead wire 2a which is soldered with a wiring pattern 1a at a periphery of an opening hole 1b using solder 3 wherein a flexible constricted portion 2c is formed at a connecting portion 22 between a body itself 2d of the electronic part 2 and a soldering portion 21 of the lead wire 2a of the electronic part 2. <P>COPYRIGHT: (C)2003,JPO

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an electronic component with a lead terminal, and more specifically, to a lead terminal of an electronic component with a lead terminal and a circuit formed around an opening or the like of a substrate into which the lead terminal is inserted. The present invention relates to an electronic component with a lead terminal for electrically connecting the wiring pattern of (1) with solder.

[0002]

2. Description of the Related Art In recent years, electronic components with lead terminals mounted on a substrate have been required to be miniaturized in electronic devices such as mobile phones, and the shape of the lead terminals of the electronic components used in those devices has been changed. , Is miniaturized so that it can be mounted at high density.

Various devices using the above electronic components with lead terminals are required to have high reliability for a long period of time in an environment where they are used. In particular, the lead terminals of the electronic components with lead terminals and the wiring patterns on the board are soldered. In the soldering part that is electrically connected with the lead terminal, to prevent the solder from cracking or the like against the thermal stress acting on the soldering part of the lead terminal caused by the difference in expansion and contraction due to temperature change, It is required to firmly hold the component on the substrate. In recent years, lead-free solder is often used, but in the case of lead-free solder,
Since it has higher strength and rigidity than conventional solder, thermal shock tends to cause microcracks in the solder on the component side of the soldered part at the initial stage and at the time of thermal shock.

Japanese Patent Laid-Open No. 9-246687 discloses a means for firmly holding an electronic component with lead terminals to a substrate. This publication proposes mechanically and firmly holding the connection between the solder and the lead terminal to improve reliability against thermal shock. As shown in FIG. 6, this conventional technique is a soldering part for a lead terminal 22a of an electronic component 22 with a lead terminal to be inserted into a substrate 11 on which a circuit wiring pattern 11a is arranged around an opening 11b. A constricted portion 22b is provided at a portion located at 44. This is because by providing the constricted portion 22b on the lead terminal 22a of the electronic component with lead terminal 22 that comes into contact with the solder of the soldering portion 44, the contact area with the solder is increased and not only the electrical connection but also the physical connection is performed. Open hole 11b
It is intended to function as a retainer for the insertion direction of.

[0005]

In the case of an electronic component typified by a relay component having a plurality of lead terminals in the longitudinal direction parallel to the substrate, the substrate is affected by heat when soldering the electronic component. When it bends, the stress concentrates most on the root of the lead terminal of the electronic component body due to its distortion.Therefore, even if a constriction is provided on the lead terminal in the soldering section as in the above-mentioned conventional technique, sufficient reliability can be obtained. The effect of improving sex cannot be expected.

Therefore, the present invention provides a lead terminal shape of an electronic component with a lead terminal, which is highly reliable even by expansion and contraction during soldering of the above-mentioned substrate and thermal shock in the usage environment of the electronic component with a lead terminal. This is a technical issue.

[0007]

[Means for Solving the Problems] Means for solving the above-mentioned problems are as follows: An electronic component having a main body and lead terminals extending from the main body, wherein the lead terminals are soldered to a circuit board. An electronic component with a lead terminal, comprising: a soldering part, and a connecting part for connecting the soldering part and the main body, and a constricted flexible part is formed in the connecting part. To do.

As a function of the above-described means, since the flexible portion is provided in the portion of the lead terminal which is not soldered (connecting portion), it occurs between the lead terminals due to the difference in thermal expansion and contraction of the board and the solder. The strain is relieved by the bending of the flexible portion, and the stress acting on the rigid portion such as the portion where the lead terminal of the electronic component and the substrate soldering portion are soldered is reduced, and by extension, the portion to be soldered. It works to avoid cracking in the.

[0009]

BEST MODE FOR CARRYING OUT THE INVENTION Embodiments of the present invention will be described below with reference to FIGS. 1, 2, 3, 4, and 5. FIG. 1 is a first embodiment of the present invention, and an example of mounting an electronic component with lead terminals on a single-sided wiring board will be described. The substrate 1 in the drawing is provided with an opening 1b, and a circuit wiring pattern 1a is provided on the lower surface around the opening 1b. A body 2d of the electronic component 2 with lead terminals is provided with a lead terminal 2a extending from the body 2d,
The lead terminal 2a is inserted into the opening hole 1b of the substrate and is electrically and mechanically coupled to the wiring pattern 1a by the solder 3. The lead terminals 2a are soldered parts 21 which are parts to be soldered to the single-sided wiring board 1.
And a connecting portion 22 that is a portion that connects the soldering portion 32 and the main body 2d, and the connecting portion 22 between the soldering portion 22 and the main body 2d has a constricted flexible portion. 2c is provided. The flexible portion 2c has a cross-sectional shape smaller than the cross-sectional area of the lead terminal 2a so that the displacement caused by the stress or strain between the main body 2d and the substrate 1 mainly due to the difference in expansion and contraction due to heat is alleviated. It forms a flexible waist. The constricted flexible portion 2c of the lead terminal 2a elastically bends, so that the inside of the solder 3 or the solder 3 and the wiring pattern 1a or the lead terminal 2a is formed.
It serves to reduce the stress applied to the joint portion of the solder and the occurrence of cracks in the joint portion of the solder 3. FIG. 2 shows a second embodiment of the present invention, which is an example of mounting an electronic component with lead terminals on a double-sided board. In the figure, the circuit wiring pattern 1a is arranged on both sides of the opening 1b of the substrate 1, and the solder 3 is spread over both sides of the substrate 1. The names and numbering of other parts have the same meaning as in FIG. The flexible portion 2c is provided in the connecting portion 22 between the soldering portion 21 and the main body 2d even in the state of implementation of FIG. 2, and is generated between the main body 2d and the substrate 1 by an external force or thermal stress. The displacement caused by bending is absorbed to reduce the stress exerted on the solder 3 by the lead terminal 2a. FIG. 3 is a schematic side view in which the flexible portion 2c of the lead terminal 2a in FIGS. 1 and 2 is partially enlarged. The constricted shape of the flexible portion 2c may be, for example, a concentric circular shape that is easily bent in all directions from the lead shaft center, or may be a rectangular cross section having a flexible directional property as shown in FIG. The constricted shape of the flexible portion 2c is designed so that the elastic force works optimally depending on the amount of bending and the material of the lead terminal 2a, and is not limited to the example shown in the drawing. FIG. 5 shows an embodiment in which the present invention is applied to an electronic component having a plurality of lead terminals 2a.

The electronic component with lead terminals 2 has a plurality of lead terminals 2a, and the lead terminals 2a are shown in FIG.
It is a form soldered to the wiring pattern 1a of the circuit provided only on the lower surface, that is, on the side opposite to the main body 2d.
In this embodiment, the lead terminal 2a having the constricted flexible portion 2c is only on the outermost side of the plurality, and the central lead terminal 2aa does not have the constricted flexible portion 2c. Other names and numbering have the same meaning as in FIG. Thus, when soldering an electronic component having a plurality of lead terminals 2a, X of the main body 2 and the substrate 1
The difference in thermal expansion and contraction in the direction (horizontal direction in FIG. 5) becomes strain, and stress acts on the soldered portion between the lead terminal 2aa located in the center of the electronic component 2 shown in FIG. 5 and the circuit wiring pattern 1a. The displacement due to the thermal expansion between the substrate 1 and the main body 2 described above is relatively small in the central portion of the electronic component 2 (see the broken line of the lead terminal 2aa shown in FIG. 5) and is large in the outer peripheral portion, that is, the edge portion (FIG. 5). Refer to the broken line of the shown lead terminal 2a).
Therefore, it is effective to provide the outermost lead terminal 2a of the electronic component 2 with the constricted flexible portion 2c. If the difference in thermal expansion coefficient between the components of the electronic component 2 and the substrate 1 is large, it is obvious that the lead terminal 2a may be provided with a flexible portion even in the central portion of the electronic component 2.

The present invention, like the prior art, uses the lead terminal 2
There is no need to change the shape of the soldering part a, and it is not necessary to change the conditions for soldering the board on which the electronic component with lead terminals according to the present invention is newly mounted.

[0012]

As described above, in the electronic component with lead terminal of the present invention, the constricted flexible portion is provided at the portion (connecting portion) on the lead terminal between the soldering portion and the electronic component body. In terms of thermal shock at the time of soldering, reliability of soldering, and the like, higher reliability can be obtained than that of electronic components with lead terminals of the related art. In consideration of the difference in the coefficient of thermal expansion of the materials used for the electronic component body and the stress such as warpage of the board generated by heat, the constriction shape of the lead terminal of the electronic component is individually determined according to the characteristics of the component. By designing, the optimum constriction shape can be set so as to absorb the stress generated in the soldered portion of the board even when the board expands and contracts or warps. Regarding the reliability of the above-described occurrence of minute cracks in the solder part, an effect has been confirmed in a thermal shock test at -30 ° C to 80 ° C, which is a typical evaluation condition for electronic components.

[Brief description of drawings]

FIG. 1 is a first embodiment of the present invention, and is a schematic enlarged cross-sectional view of a lead terminal in a state where an electronic component with lead terminal is mounted on a single-sided wiring board.

FIG. 2 is a second embodiment of the present invention, and is a schematic enlarged cross-sectional view of a lead terminal in a state where electronic components with lead terminals are mounted on a double-sided wiring board.

FIG. 3 is a schematic enlarged side view of a flexible portion of the lead terminal according to the present invention.

FIG. 4 is a schematic enlarged cross-sectional view of another embodiment of the flexible portion of the lead terminal according to the present invention.

FIG. 5 is a schematic side view and a schematic plan view of another embodiment of an electronic component having a plurality of lead terminals according to the present invention.

FIG. 6 is an embodiment of a lead terminal in the prior art.

[Explanation of symbols]

1 substrate 1a wiring pattern 1b Open hole 2 electronic components 2a lead terminal 21 Soldering area 22 Connection site 2c flexible part 2d body 3 solder

Claims (3)

[Claims] 1. An electronic component having a main body and a lead terminal extending from the main body, wherein the lead terminal connects a soldering portion to be soldered to a circuit board, and the soldering portion and the main body. An electronic component with a lead terminal, comprising: a connecting part, and a constriction-shaped flexible part formed in the connecting part. 2. The electronic component with lead terminals has a plurality of the lead terminals, and at least one of the lead terminals has the constricted flexible portion. The electronic component with a lead terminal according to claim 1. 3. The electronic component with lead terminals according to claim 2, wherein the flexible portion is formed on the lead terminal located on the outermost side of the main body.