JPH0449610A - Bush for bead core and packaging method of bead core - Google Patents

Abstract

PURPOSE:To enable simple execution of an operation of packaging a bead core on a printed wiring board and complete attainment of insulation by having integrally a small-diameter part fitted elastically in the center hole of the bead core and retained in the hole and a large-diameter part joining coaxially to one end of the small-diameter part and by forming a center hole through which an electric line pierces. CONSTITUTION:A bush 2 is constructed of an electrically insulative elastic material such as rubber and has integrally a small-diameter part 2a having an outside diameter making it possible for the part to be fitted elastically in the center hole 1a of a bead core 1 and retained in the hole 1a and having substantially the same length as the core and a large- diameter part 2b being continuous in the shape of a flange to one end of the small-diameter part 2a coaxially, while a center hole 2a through which an electric line pierces is formed in the centers of these parts. When the bead core 1 is fitted to a lead frame 3a of a circuit element 3 by using the bush 2 for the bead core, first the small-diameter part 2a of the bush 2 is pushed into the center hole 1a of the bead core 1, so that the two components be integrated. Then, the lead frame 3a is pushed into the center hole 2c of the bush 2 from the side of the small-diameter part 2a, in respect to the bead core 1 with the bush 2, and the fore end side of the lead frame 3a is made to pierce through the side of the large-diameter part 2b and project therefrom.

Description

Detailed Description of the Invention (Field of Industrial Application) The present invention relates to a bushing used in mounting a bead core made of a small cylindrical magnetic material used to prevent noise by penetrating the lines of an electric circuit. This article relates to a mounting method using a bush.

(Prior art) For example, when mounting semiconductor elements such as transistors and diodes, and electric circuit components such as connectors on a printed wiring board, bead cores are fitted into the lead frames of these circuit components, and the tips of the lead frames that pass through the bead cores. A noise prevention method is known in which a part is connected to a printed wiring board.

When using a bead core in this way, the surface of the bead core made of amorphous magnetic material is coated with an insulating layer, and when mounting circuit components such as transistors and connectors on a printed wiring board, the bead core is first attached to a lead frame. The component with the bead core will be inserted into the printed wiring board.

(Problem to be solved by the invention) The conventional bead core mounting method as described above first requires a troublesome process of coating the core surface with an insulating layer, and if the insulation is not perfect, short circuits may occur through the bead core. There was a problem that there was a risk.

In addition, even if a bead core is fitted into a lead frame of a circuit component, there is no way to hold the core in the lead frame, so when attaching it to a printed wiring board with the tip of the lead frame facing downward, hold the core with your fingers. If not, the bead core will fall off. Therefore, the work of inserting the circuit component with the bead core into the printed wiring board has become extremely troublesome.

This invention was made in view of the conventional problems mentioned above, and its purpose is to easily attach the bead core to the lead frame of a circuit component and mount it on a printed wiring board, and to make it easier to attach the bead core to the lead frame of a circuit component and to mount it on a printed wiring board. An object of the present invention is to provide a bead core bushing that can be completely insulated and a bead core mounting method using the bushing.

(Means for Solving the Problems) The bead core bushing according to the present invention is made of an electrically insulating elastic material, and has an outer diameter that elastically fits into the center hole of the bead core and is held in the hole. It integrally has a small diameter part of approximately equal length and a large diameter part coaxially connected to one end of the small diameter part, and a center hole is formed in the center of these parts through which the electric line passes.

Also, using this bead core bushing, first elastically fit the small diameter part of the bushing into the center hole of the bead core to integrate the two, and then insert the circuit component into the center hole of the bushing from the small diameter part side. The lead frame is elastically penetrated, and the penetrating tip of the lead frame is connected to the wiring board.

(Function) By elastically fitting the small diameter portion of the bushing into the center hole of the bead core, both are held integrally, and the inner periphery of the center hole of the core is completely insulated by the bush. When a lead frame of a circuit component is elastically inserted into the center hole of the bead core with the bushing from the small diameter side of the bushing, the bushing and bead core are integrally connected to the lead frame by the elastic force of the bushing. , and will not fall even if you do not hold them down with your fingers.

(Example) FIG. 1 shows a bead core bushing and its usage according to an example of the present invention. In the figure, 1 is a small cylindrical bead core made of amorphous magnetic material, and 2
3 indicates a bead core bushing according to the present invention, and 3 indicates a circuit component such as a transistor to which the bead core 1 is attached.

The bushing 2 is made of an electrically insulating elastic material such as rubber.
A small diameter portion 2a having an outer diameter (slightly larger than the inner diameter of the hole 1a) and approximately the same length as the core 1, which elastically fits into the center hole 1a of the bead core 1 and is held within the hole la; A central hole 2 that integrally has a large diameter portion 2b coaxially continuous in the form of a flange at one end, and an electric line passes through the center of the large diameter portion 2b.
c is formed. The joint between the small diameter part 2a and the large diameter part 2b is a tapered curved surface, and when the small diameter part 2a is completely pushed into the center hole 1a of the bead core 1,
The size is such that the tip of the small diameter portion 2a slightly protrudes from the end surface of the core 1. Further, the large diameter portion 2b has approximately the same size as the outer diameter of the bead core 1. Furthermore, the inner diameter of the center hole 2c is the lead frame 3a of the circuit element 3 to be mounted.
Set it slightly smaller than the width of .

When attaching the bead core 1 to the lead frame 3a of the circuit element 3 using the bead core bushing 2 configured as described above, first push the small diameter part 2a of the bushing 2 into the center hole 1a of the bead core 1 to integrate both parts. do. Next, for the bead core 1 with the bushing 2 attached, push the lead frame 3a into the center hole 2c of the bushing 2 from the small diameter part 2a side, and insert the tip side of the lead frame 3a into the large diameter part 2b.
Make it penetrate and protrude from the side. In this state, bead core 1
And it is not necessary to hold down Bush 2, but Bush 2
The core 1 and the bushing 2 are held on the lead frame 3a by the elastic force. After this, the circuit element 3 with the bead core 1 attached is mounted on a printed wiring board (not shown), but at that time, it is possible to insert the lead frame 3a into the board with the tip end facing downward, as compared to the conventional method. Core 1 will not fall like this. Automatic insertion machines can therefore also be used.

The bead core bushing 2 of the present invention is not only applicable to attaching bead cores to circuit elements such as transistors, but also to attaching bead cores to electrical circuit lines such as covered conductors and bare conductors. In that case as well, the core can be stably held at a predetermined position on the line and can be completely insulated from the line.

(Effects of the Invention) As explained in detail above, by using the bead core bushing according to the present invention, the work of attaching the bead core to the lead frame of a circuit element such as a transistor and mounting it on a printed wiring board is greatly simplified. This can be done simply and efficiently, and the bushing can reliably insulate between the core and the lead frame and between the core and the wiring board without coating the surface of the core with an insulating layer.

[Brief explanation of the drawing]

FIG. 1 is a perspective view showing the structure of a bead core bushing according to an embodiment of the present invention and an example of its usage. 1...Bead core 1a...Center hole 2...Bushing 2a...Small diameter part 2b...Large diameter part 2C...Center hole 3...Circuit parts 3a...Lead frame

Claims (2)

[Claims] (1) A small diameter part made of an electrically insulating elastic material, which elastically fits into the center hole of the bead core and is held in the hole, and has an outer diameter and approximately the same length as the core, and one end of this small diameter part. A bush for bead cores that has a large diameter part that is coaxially connected, and a center hole is formed in the center of these parts, through which an electric line passes. (2) elastically fitting the small diameter portion of the bushing according to claim 1 into the center hole of the bead core to integrate the two;
A bead core mounting method in which a lead frame of a circuit component is elastically passed through the center hole of the bushing from the small diameter portion side, and the penetrating tip of the lead frame is connected to a wiring board.