JP2923428B2 - Electronic components - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a resin-sealed surface-mount type electronic component such as a diode, a capacitor, a transistor, and an IC, and a mounting structure of the electronic component.

[0002]

2. Description of the Related Art Electronic components of this kind, for example diodes E
As shown in FIG. 6, the resin sealing portion 11 has a substantially rectangular parallelepiped shape.
A pair of lead terminals 12 buried at one end in the resin sealing portion 11 and opposed to each other so that the other end protrudes from the side surface of the resin sealing portion 11; A semiconductor element (diode element) 13 mounted at one end of the pair of lead terminals 12;
A metal wire for electrically connecting the diode element to the other end of the pair of lead terminals;

In general, as shown in FIG. 6, the above-mentioned diode E is formed by replacing the tip of a lead terminal 12 protruding from a resin sealing portion 11 with a mounting board B such as a printed board. It is fixed to the surface of the mounting substrate B with an adhesive C so as to correspond to a predetermined connection portion of the wiring provided on the surface, and this is subjected to reflow and soldering,
The tip of the lead terminal 12 of the diode E and the connection portion of the wiring of the mounting board B are connected by solder D and mounted.

[0004]

In recent years, the following problems are likely to occur as the size of the electronic components further increases with the improvement of electronic technology. 7 (a) and 7 (b), the lower surface 12a of the tip of the lead terminal 12 is located below or above the bottom surface 11a of the resin sealing portion 11 with the downsizing of the electronic component. And the thickness of the lead terminal 12 is reduced, and the strength of the lead terminal 12 is reduced. When the lower surface 12a of the leading end of the lead terminal 12 is located too lower than the bottom surface 11a of the resin sealing portion 11, when this is soldered and mounted on a mounting board, when it is fixed to the mounting board with an adhesive, ,
In combination with the variation in the amount of the adhesive applied, as shown in FIG. 8, the bottom surface 11a of the resin sealing portion 11 does not make sufficient or no contact with the adhesive C, resulting in incomplete fixing. Due to a mounting defect or a pressure at which the lead terminals 12 are pressed against the mounting substrate B when mounting on the mounting substrate B for fixing with the adhesive C, the lead terminals 12 are deformed or stress is applied to the resin sealing portion 11. Or even reach.

On the other hand, when the lower surface 12a of the leading end of the lead terminal 12 is located above the bottom surface 11a of the resin sealing portion 11, when this is soldered to a mounting board, as shown in FIG. The lead terminals 12 are pulled downward due to shrinkage when the molten solder D ′ solidifies, and there is a danger that the lead terminals 12 will be broken or the resin sealing portion 11 will be cracked or cracked.

[0006] In order to solve the above problems,
The lower surface 12a of the leading end of the lead terminal 12 is
Strict processing accuracy is required to always process the bottom surface 11a at a fixed position. However, the position variation problem cannot be completely solved, and it is necessary to reduce the variation as much as possible. Then, a decrease in productivity or the like is caused.

SUMMARY OF THE INVENTION It is an object of the present invention to provide a technique capable of reliably mounting a lead terminal even if the processing of the lead terminal varies, and reducing a stress applied to an electronic component at the time of mounting.

[0008]

SUMMARY OF THE INVENTION The present invention has been made to achieve the above object, and relates to the following electronic component and a mounting structure of the electronic component. An electronic component having lead terminals protruding from a side surface of a resin sealing portion and extending downward from the resin sealing portion, wherein a buffer material is provided on a bottom surface of the resin sealing portion. parts.

A concave portion is provided on a bottom surface of the resin sealing portion, and a cushioning material is integrally provided in the concave portion.
Electronic components as described.

[0010]

According to the present invention, when an electronic component is mounted on a mounting board, the electronic component is mounted between the bottom surface of the resin sealing portion of the electronic component and the mounting board via a buffer material. Therefore, even if the lower surface of the leading end of the lead terminal is located below the bottom surface of the resin sealing portion, mechanical stress applied to the electronic component when the electronic component is mounted on the mounting board during soldering is reduced. It can effectively reduce the deformation or breakage of the lead terminals, as well as the occurrence of cracks or cracks in the resin sealing portion. Can be performed more reliably. Further, even when the lower surface of the tip of the lead terminal is located above the bottom surface of the resin sealing portion, the buffer material effectively absorbs the pulling force of the lead terminal due to shrinkage during solidification of the solder paste, The stress applied to the lead terminals and the resin sealing portion can be reduced. Therefore, even if there is some variation in the processing of the lead terminals, it is possible to effectively alleviate the shock applied to the electronic component at the time of mounting, reduce the occurrence of electrical and mechanical defects in the electronic component, and to reduce the mounting failure. Can also be significantly reduced. According to the present invention, the accuracy of the positional relationship between the resin sealing portion and the external lead in the conventional electronic component is 1.
The present invention can be applied even if the width is 5 times or more wide.

[0011]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, an embodiment in which the present invention is applied to a surface-mount type diode which is a two-terminal component will be described, and the features of the present invention will be described in more detail. It will not be done. As shown in FIG. 1, the diode A in the present embodiment has a substantially rectangular parallelepiped resin sealing portion 1 and an internal lead 2 a embedded in the resin sealing portion 1.
a, 2ba and external leads 2ab, 2bb protruding from the side surface of the resin sealing portion 1 and a pair of oppositely arranged lead terminals 2a, 2b, and within the resin sealing portion 1, the pair of lead terminals 2a, 2b. One of the lead terminals 2
a diode element 3 mounted on the tip of the internal lead 2aa, and the internal lead 2 of the diode element 3 and the other lead terminal 2b of the pair of lead terminals 2a and 2b.
It has a metal wire 4 for electrically connecting to the tip of ba, and a cushioning material 5 provided on the bottom surface of the resin sealing portion 1.

The material of the cushioning material 5 is not particularly limited as long as it has insulation and elasticity and has heat resistance enough to hold an electronic component on a mounting board during solder mounting. In particular, the elasticity is such that the elasticity of the diode A supports its own weight, and the amount of displacement during compression is large in the compression direction and small in other directions, and further, the repulsive force in the compression direction during compression It is more preferable that the shrinkage force when solidifying from the molten state of the solder used for mounting is smaller, more specifically, for example, urethane foam, a resin material such as a silicone resin, a rubber material such as a silicone rubber and the like. it can.

The thickness of the cushioning material 5 is determined in consideration of the thickness of the adhesive used for fixing the diode A on the mounting board at the time of mounting, and when the diode A is fixed with the adhesive. External lead 2 of lead terminals 2a, 2b
It is preferable that the lower end portions of ab and 2bb are provided so as to be in contact with or slightly above the connection portion of the wiring on the mounting board. Therefore, it is preferable that the lower surface of the cushioning material 5 be located substantially the same or slightly higher than the lower surfaces of the distal ends of the external leads 2ab and 2bb.

As a method of providing the cushioning material 5 on the bottom surface of the resin sealing portion 1, for example, as shown in FIG. 2A, a pair of lead terminals 2a,
In the state of the lead frame 2 in which a plurality of 2b are connected in a row,
It is effective and preferable in terms of work to provide the cushioning material 5 on the bottom surface of each resin sealing portion 1 by coating and solidifying or attaching with an adhesive such as an epoxy adhesive. Then, after providing the buffer material 5 as described above, the diode A is divided into individual diodes A, and the lead terminals 2a and 2b are processed into a predetermined shape to obtain the diode A of the present embodiment. Also, as shown in FIG.
The cushioning material is affixed to the bottom surface of the resin sealing portion 1 along the longitudinal direction of the lead frame 2 provided with the resin sealing portion 1 as a strip-shaped sheet 5 ′. In the step of cutting predetermined portions of the lead terminals 2a and 2b, or by cutting before and after the step, and removing the same, and providing the cushioning material 5 on the bottom surface of the resin sealing portion 1, the operation is more simplified. It can be performed quickly.

Further, in the diode A of the above embodiment, the cushioning material 5 is provided on the bottom surface of the resin sealing portion 1 which is flat, but as shown in FIG. A concave portion 1a may be provided on the bottom surface, and a cushioning material 5 may be provided in the concave portion 1a so as to protrude from the bottom surface of the resin sealing portion 1.
By doing so, the thickness of the cushioning material 5 can be made relatively large, so that the cushioning effect can be further increased.

Next, the diode A constructed as described above is used.
FIG. 4 shows a state in which is mounted on the mounting board B by soldering. The diode A is mounted on the mounting board B such that the tips of the external leads 2ab and 2bb correspond to predetermined connection portions of wiring provided on the surface of the mounting board B such as a printed board.
After fixing the front surface and the cushioning material 5 provided on the lower surface of the resin sealing portion 1 of the diode A with an adhesive C, this is fixed to the external lead 2ab, by reflow soldering or the like.
2bb and the connection portion of the wiring are connected by solder D and mounted.

In the above embodiment, the lead terminals 2a, 2b
The external leads 2ab and 2bb are
Are bent immediately after protruding from the side surface of the external lead 2ab, and extended to the bottom surface along the side surface of the resin sealing portion 1.
2bb is bent outward from the bottom side of the resin sealing portion 1, but the present invention is not limited to this.
(A) and (b), the external lead 2a
You may bend the front-end | tip part of b, 2bb inward toward the bottom surface side of the resin sealing part 1.

The present invention is not limited to two-terminal components such as the diode or the capacitor, but can be applied to multi-terminal components such as transistors and ICs.

[Brief description of the drawings]

FIG. 1 is a side view showing a diode according to an embodiment of the present invention.

FIGS. 2A and 2B are a bottom view of a lead frame and a bottom view of another example illustrating a step of providing a buffer material on a bottom surface of a resin sealing portion of a diode in an embodiment of the present invention.

FIG. 3 is a partially cutaway sectional view showing a diode according to another embodiment of the present invention.

FIG. 4 is a sectional view showing a mounting structure of the present invention.

FIGS. 5A and 5B are a side view and a partially cutaway sectional view showing a diode according to still another two embodiments of the present invention. FIGS.

FIG. 6 is a cross-sectional view showing a conventional diode and its mounting structure.

FIGS. 7A and 7B are side views for explaining variations in processing of a lead terminal in a conventional diode. FIG. 7A is a diagram illustrating a case where a tip end of a lead terminal is located below a bottom surface of a resin sealing portion.
And (b) the case where the tip of the lead terminal is located above the bottom surface of the resin sealing portion.

FIG. 8 is a side view for explaining a mounting state of the conventional diode shown in FIG.

9 is a cross-sectional view illustrating a mounting state of the conventional diode shown in FIG. 7 (b).

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Resin sealing part 2a, 2b Lead terminal 2aa, 2ba Internal lead 2ab, 2bb External lead 3 Diode element 4 Metal wire 5 Buffer material 6 Depression A Diode B Mounting board C Adhesive D Solder

Claims (2)

(57) [Claims] An electronic component having lead terminals protruding from a side surface of a resin sealing portion and extending downward from the resin sealing portion, wherein a cushioning material is integrally formed on a bottom surface of the resin sealing portion. An electronic component characterized by being provided. 2. A concave portion is provided on a bottom surface of the resin sealing portion.
The cushioning material is integrally provided in the portion.
Electronic components as described.