JPH11195862A - Mounting structure for electronic component - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a mounting structure, for an electronic component, which cancels the vibration of the electronic component and which prevents an unpleasant sound caused by the vibration when especially the electronic component, generating the vibration, such as a transformer or the like constituting a part of an oscillation circuit is mounted. SOLUTION: An electronic component 10 is connected to a printed-circuit board 30, made of a thermosetting resin, via a flexible board 20 which is provided with flexibility. A vibration which is generated by the electronic component 10 is cancelled by the flexible board 20, and it is not transmitted to the printed-circuit board 30. As a result, it is possible to prevent an unpleasand sound caused by the resonance of the electronic component 10 with the printed- circuit board 30.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a mounting structure of an electronic component, and more particularly to a mounting structure of an electronic component for reducing a vibration sound of a substrate on which an electronic component such as a coil and a transformer constituting a part of an oscillation circuit is mounted.

[0002]

2. Description of the Related Art Conventionally, electronic components such as coils and transformers that constitute a part of an oscillation circuit are fixedly mounted directly on an electronic circuit board or a printed board by soldering or the like. A printed board is generally formed by molding a thermosetting resin such as an epoxy resin, and has a thickness of a hard plate-like (ie,
(Having hardness). As a method of soldering to such a printed board, so-called dip soldering and flow soldering are known. Dip soldering is to insert a terminal of an electronic component into a through hole formed in a printed circuit board and then immerse the terminal in a melted solder layer to electrically and fixedly connect the printed circuit board and the electronic component by soldering. . In the flow soldering, a solder paste is applied to a pattern position to be connected on a printed circuit board, an electronic component is positioned thereon, and then the solder is melted and fixed by heating.

[0003]

The conventional mounting structure for electronic components is to secure the electrical connection between the electronic components and the printed circuit board, and to fix both by direct soldering due to the cost problem. Is common. However,
When an electronic component that constitutes a part of an oscillation circuit such as a transformer is mounted, the vibration of the electronic component is directly transmitted to the board,
In some cases, an unpleasant vibration sound is generated by resonance with the substrate. In particular, printed circuit boards (circuit boards) used in electronic devices are often hard and have a much larger area than electronic components. When the substrate is supplied and resonates with the vibration of the transformer, the substrate may function as a speaker and amplify the vibration sound. When the power supply frequency supplied to the transformer is low, an unpleasant sound “G” is generated, and as the frequency increases, a high sound “P” is generated.

More specifically, in an EL inverter transformer for driving an EL (electroluminescence) used as a backlight of a liquid crystal display, an EL inverter transformer is used.
In order to ensure sufficient luminance that L can be visually recognized, it is necessary to supply high-frequency (several hundred to several thousand Hz) power.
In the EL inverter transformer, an LC oscillation circuit is connected to a primary winding side, and the primary winding plays a role of a coil of the oscillation circuit (that is, constitutes a part of the oscillation circuit), and is boosted to a secondary winding. Generates high frequency power. At this time, a magnetic flux due to the high-frequency current is generated in the core, and the transformer causes micro-vibration accordingly. Since electronic devices equipped with a liquid crystal display are generally small and portable, and are often used close to the user's face, the sound generated by the resonance between the transformer and the substrate is generated by the user. Feels very unpleasant and harsh. Therefore, an object of the present invention is to provide an electronic component mounting structure that prevents or suppresses harsh vibration noise due to vibration of a substrate on which the electronic component is mounted and does not cause discomfort to a user.

[0005]

According to the electronic component mounting structure of the present invention, a flexible substrate having flexibility is interposed between a printed board and an electronic component, and the electronic component is fixed to the flexible substrate. Is connected to a printed circuit board. That is, according to the mounting structure of the present invention, an electronic component in which a plurality of input / output terminals are formed and which vibrates due to supply of electric power, a predetermined circuit pattern is wired on the surface thereof, and connected to the input / output terminal of the electronic component A printed board on which a plurality of terminal portions are formed, and a flexible board which is disposed between the printed board and the electronic component and is made of a flexible material for connecting the terminal portion of the printed board and the input / output terminal of the electronic component. Prepare. The flexible substrate has a first terminal for connecting to a terminal portion of the printed circuit board at an end thereof, and a second terminal for connecting to an input / output terminal of the electronic component in a region excluding the first terminal. By forming and connecting the first terminal to the terminal portion of the printed circuit board in a state where the input / output terminals of the electronic component are connected to the second terminal, the electronic component is indirectly connected to the printed circuit board. This is to absorb the vibration of the parts.

[0006]

According to the present invention, even if the electronic component vibrates, the vibration is absorbed by the flexible printed circuit board having flexibility, and the vibration is not transmitted to the hard printed circuit board. It is possible to prevent or significantly suppress the generation of unpleasant noise by resonance with the printed circuit board and amplification.

[0007]

FIG. 1 is a side view showing an electronic component mounting structure according to an embodiment of the present invention. In FIG. 1, a mounting structure of an electronic component according to this embodiment includes a transformer 10 as an example of the electronic component.
Is mounted on the flexible substrate 20 and the flexible substrate 2
By connecting 0 to the printed circuit board 30, the vibration of the transformer 10 is absorbed by the flexible board 20 and is not transmitted to the printed circuit board 30. More specifically, it is constructed and assembled as described in detail with reference to FIGS.

FIG. 2 is an exploded perspective view of each part included in the electronic component mounting structure, and FIG. 3 is a line III-I in FIG.
It is sectional drawing of the transformer which follows II. However, the input / output terminals 14 and 15 are omitted in FIG. Next, FIGS.
The details of the mounting structure of the electronic component and each component included therein will be described with reference to FIG.

The transformer 10 includes a set of E-shaped cores 11a,
11b, and includes a flat rectangular core 11. The core 11 is made of a magnetic material (for example, Mn-based ferrite having a high magnetic permeability), and has ring-shaped cores 111 and 112 formed in the center thereof, and side walls 113 and 114 formed on side surfaces along the first direction. It is formed. A bobbin 13 around which a coil 12 is wound is inserted through the core 11. The bobbin 13 is formed by integrally forming ring-shaped disks 132 and 133 on both sides of a cylindrical portion 131 made of an insulating material. The coil 12 is wound around the cylindrical portion 131.
The coil 12 has a primary coil and a secondary coil, and a lead wire is connected to an appropriate position of the primary coil. Both ends of a primary coil and a lead wire of the coil 12 are respectively connected to a plurality of input terminals 14, and both ends of a secondary coil are connected to an output terminal 15. The plurality of input terminals 14 and output terminals 1
Numerals 5 are both ends of the core 11 in the first direction, supported by the corresponding terminal support portions 16 and 17, and are fixedly supported in a direction orthogonal to the first direction. Then, the discs 132, 133 of the bobbin 13 and the core cores 111,
The E-shaped cores 11a and 11b around the periphery 112 are bonded by an adhesive 18 such as a rubber type. Also, core 1
1 is a state in which the E-shaped cores 11a and 11b are
Side walls 113, 11 of E-shaped cores 11a, 11b, respectively
The adhesive is applied by applying an adhesive 19 from the side surface (or the outer peripheral surface). In this case, the E-shaped cores 11a and 11b
The reason why the adhesive 19 such as an epoxy resin is applied from the side surface (or the outer peripheral surface) of the side walls 113 and 114 instead of the opposing end surfaces of the respective side walls 113 and 114 to adhere to each other is as follows.
If they are bonded at the opposing end faces of 4, the magnetic path will be interrupted by the insulating material, leading to a decrease in magnetic permeability and preventing efficient generation of magnetic flux. Note that the bobbin 13 and the terminal support portions 16 and 17 may be integrally formed of the same insulating material. Thereby, the number of parts and the number of assembling steps can be reduced, and the cost can be reduced.

The flexible substrate 20 is made of a flexible insulating material, for example, a polyimide film having a shape larger than the planar shape of the transformer 10 (for example, a shape larger in the first direction). The input terminal 1 of the transformer 10 is provided on one main surface (the upper surface in the drawing) of the flexible substrate 20.
4 and a position corresponding to the output terminal 15, a plurality of terminals 21 and 22 are formed at a position slightly apart from the plurality of terminals 21 and 22 in the first direction (for example, by a distance d). Printed circuit board 30 at a remote position)
A plurality of terminals 23 and 24 for connection to the terminal are formed.
The plurality of terminals 23 and 24 are substantially 1/1 of the longitudinal direction.
In order to bendable at 2, the terminal is formed in a belt shape longer than the terminals 21 and 22. According to experiments, it has been confirmed that the distance d between the terminal 21 and the terminal 23 or between the terminal 22 and the terminal 24 is effective to sufficiently prevent vibration if the distance is 3 mm or more. Can be reduced. The corresponding terminals 14 and 15 of the transformer 10 are soldered to the terminals 21 and 22 of the flexible substrate 20.

The printed board 30 is a flexible board 2
0, terminals 31 and 32 at positions corresponding to terminals 23 and 24, respectively.
Are formed, a circuit pattern necessary for achieving the function of the electronic device is formed, and appropriate components are mounted. Then, the terminals 23 and 24 of the flexible board 20 on which the transformer 10 is mounted are bent in U-shape, respectively, and are positioned at positions corresponding to the terminals 31 and 32 of the printed circuit board 30, and the terminals 23 and 31 and the terminals 24 are arranged. And the terminals 32 are soldered respectively. These soldering methods are so-called flow soldering or manual soldering. Terminal 3 for flow soldering
Solder is placed on the terminal 1 and the terminal 32, and the terminal 23 is bent in a U-shape on the terminal 31 and a part of the terminal is pressed to apply hot air to melt and fix the solder on the terminal 31. The terminal 24 is bent in a U-shape on the terminal 32 and hot air is applied thereto to melt and fix the solder. In the case of manual soldering, the terminal 23 is placed on the terminal 31 (or 32).
(Or 24) is bent in a U-shape and positioned.
This is performed by attaching the melted solder from the side of 3 (or 24). Before soldering the flexible board 20 to the printed board 30, the flexible board 2
If the terminals 23 and 24 at both ends of the flexible substrate 20 are bent and the back surface thereof is bonded with double-sided tape, or the back surface of the portion of the flexible substrate 20 where the transformer 10 is mounted is temporarily fixed with double-sided tape, etc. Efficiency can be further improved.

As described above, the mounting structure in which the transformer 10 and the printed circuit board 30 are indirectly connected to each other via the flexible substrate 20 is such that even if a high-frequency current flows through the transformer 10 and vibration is generated, The vibration is absorbed or attenuated in the area between the terminals 21 and 23 and / or the area between the terminals 22 and 24 of the flexible substrate 20, and the vibration of the transformer 10 is directly transmitted to the printed circuit board 30. It can be prevented (or suppressed), and the generation of harsh vibration noise from the printed circuit board 30 can be prevented (or significantly reduced). In particular, vibration occurs at the abutting portions of the side walls 113 and 114 of the E-shaped core 11a and the side walls 113 and 114 of the E-shaped core 11b.
It is not transmitted to. Also, the E-shaped cores 11a, 11
Since b and the bobbin 13 are fixed to each other with a rubber-based resin adhesive, vibration caused by friction between the core 11 and the bobbin 13 can also be reduced, and the harsh sound (vibration sound) generated from the transformer 10 can be further reduced. Generation of unpleasant sounds can be prevented.

When the number of input / output terminals of the transformer 10 is small, the input / output terminals 14, 21 and 23 are formed only on one side in the first direction. Connect the terminal 23 to the printed circuit board 30
, And the input / output terminal 15, the terminal 22, the terminal 24, and the terminal 32 may be omitted. In that case, in order to prevent the position of the flexible substrate 20 from shifting, it is sufficient to fix the other side of the flexible substrate 20 to the printed circuit board 30 with a double-sided tape.

In the above-described embodiment, the case of a transformer (an output transformer or an oscillation transformer forming a part of an oscillation circuit) has been described as an example of the electronic component. However, it is needless to say that the technical idea of the present invention can be applied to other electronic components that generate minute vibrations when supplied with electric power, such as a step-up transformer, a small motor, and a coil constituting a part of an oscillation circuit.

[Brief description of the drawings]

FIG. 1 is a side view showing an electronic component mounting structure according to an embodiment of the present invention.

FIG. 2 is an exploded perspective view of each component used in the mounting structure of the electronic component.

FIG. 3 is a cross-sectional view of the transformer along a line III-III in FIG.

[Explanation of symbols]

 Reference Signs List 10: Transformer as an example of electronic component 11; Core 12; Winding (coil) 13; Bobbin 14, 15; I / O terminal 20; Flexible board 21, 22, 23, 24; Terminal 30; , 32; terminal

 ──────────────────────────────────────────────────続 き Continuing on the front page (72) Inventor Kazuto Shimokawa 1049 Oda, Tateiwa, Iizuka-shi, Fukuoka Prefecture Inside Kyushu Mitsumi Corporation

Claims (3)

[Claims] 1. A mounting structure for an electronic component incorporated in an electronic device, comprising: an electronic component having a plurality of input / output terminals formed therein, the electronic component generating vibration by supply of electric power, a predetermined circuit pattern being wired on a surface of the electronic component, A printed circuit board on which a plurality of terminal portions connected to the input / output terminals of the electronic component are formed, and a flexible material, which is disposed between the printed circuit board and the electronic component; A flexible board for connecting an input / output terminal, wherein the flexible board has a first terminal connected to a terminal of the printed circuit board at an end thereof, and an electronic component in a region excluding the first terminal. Forming a second terminal for connection with the input / output terminal of the electronic component, and connecting the first terminal to the terminal portion of the printed circuit board with the input / output terminal of the electronic component connected to the second terminal. And an indirect connection between the electronic component and the printed circuit board. 2. The electronic component is a transformer having a flat shape that forms a part of an oscillation circuit. The flexible substrate has an opening between the first terminal and the second terminal, The vibration absorbing device according to claim 1, wherein the vibration is absorbed by an elastic force of a portion between a second terminal connected to the input / output terminal of the transformer and the first terminal connected to the printed circuit board. Mounting structure for electronic components. 3. The electronic component is a flat transformer that forms a part of an oscillation circuit, and has input / output terminals formed on one side surface and the other side surface thereof. A third terminal is formed at an end opposite to the first terminal, and the second terminal and the fourth terminal are formed in a region between the first terminal and the third terminal. The electronic component mounting structure according to claim 1, wherein an input / output terminal of the electronic component is connected to a fourth terminal, and the first terminal and the third terminal are connected to a plurality of terminals of the printed circuit board.