JPH06181123A - Bead core for absorbing noise - Google Patents

Abstract

PURPOSE:To improve the pitch-length accuracy and noise absorbing ability of bead cores by providing a recessed section halfway between two holes each in each bead core. CONSTITUTION:A lead frame 6 is folded in a U-shape and passed through one hole 2 after the frame 6 is passed through another hole 2. When signals on a substrate pass through the frame 6, unnecessary high-frequency radiation noise is absorbed by bead cores 1 made of a ferrite. Since the grooves 5 of the cores 1 can be formed so that the grooves 5 can be easily engaged with projections 8 of a case 7 through packaging work, the workability can be improved. In addition, since the grooves 5 can be formed almost parallel to the two holes 2 and the thickness around the holes 2 become nearly uniform, no excessive strain is generated and the accuracy of the positions, shapes, etc., of the holes and the pitch length of the core 1 are improved. As a result, the absorbing abilities of the cores 1 become uniform. Moreover, since the thicknesses 1c of the groove 5 sections are slightly thicker than those 1b of the hole 2 sections and the side faces of the cores 1 are sloped, no excessive strain is generated at the time of extrusion molding and sintering. Therefore, the cores 1 do not crack during the manufacturing process and are not broken by residual strains.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a noise absorbing bead core.

[0002]

2. Description of the Related Art Conventionally, a bead core for absorbing high frequency unwanted radiation noise has two holes in which lead frames are inserted in parallel.
A two-hole type having a book is widely used.

A conventional two-hole type noise absorbing bead core has, for example, those shown in FIGS. 4 and 5. 4 and 5 show an example of a conventional two-hole type noise absorbing bead core, FIG. 4 (a) is a front view seen from the opening direction of the hole, FIG. 4 (b) is a side view, and FIG. 5 (a). Is a front view seen from the opening direction of the hole, and FIG. 5B is a plan view. The front shape of the two-hole type bead core 1 is rectangular. Two holes 2
Is a rectangular hole through which a lead frame (not shown) is inserted, and penetrates substantially parallel to each other with a pitch length 3 which is about three times the length of the long side of the hole cross section as a mutual interval. ,
Further, the two holes 2 are bored from the core surface 1a at intervals equal to or slightly larger than the length of the long side or the short side of the hole cross section.

In the core 1, a lead frame (not shown) is inserted into one hole 2 and then folded back into the other hole 2 into a U shape. When the bead core 1 is mounted on the substrate, when the signal on the substrate passes through the lead frame (not shown), the high frequency unwanted radiation noise contained in the signal is absorbed by the ferrite bead core 1 and is not radiated to the outside. . In many cases, a plurality of bead cores 1 are housed in a case and used as a package.

[0005]

Since the conventional two-hole type noise absorbing bead core is constructed as described above, when the ferrite powder is extrusion-molded and then sintered and molded, the holes are not formed. Since it penetrates two holes, the contraction is not performed uniformly, and it is not possible to sufficiently secure the accuracy of the position and shape of the hole, and the outer shape cannot be sufficiently accurate. The absorption performance of high frequency unwanted radiation noise depends on the shape and size of the bead core. In particular, since it depends largely on the pitch length 3 which is the distance between the two holes, if the accuracy of the position and shape of the holes is not sufficient, the irregularity in absorbing high frequency unwanted radiation noise will become large and the quality assurance. There was a quality problem that was difficult to do. Further, due to insufficient shape and size, the work of inserting the lead frame into the hole 2 is not smoothly performed, and the work of accommodating a plurality of cases in a case and making them into a package is also not performed smoothly. Was. Further, in the packaging process, the workability is poor because the bead core has no unevenness for positioning.

Further, since the two holes penetrate through, when the molding is carried out by extrusion molding and subsequent sintering, the shrinkage is not uniform, so that the surface corresponding to between the two holes has a large distortion. That is, there is a problem in that the manufacturing yield is low, that is, cracks tend to occur at the positions of the cracks 4 shown in FIG. 5 during manufacturing, or there is damage due to residual strain.

In order to solve the above problems, the present invention has a high precision pitch length, has a good high-frequency unnecessary radiation noise absorption performance, and prevents cracks during manufacturing, and also forms a package. An object of the present invention is to provide a noise absorbing bead core having improved workability.

[0008]

According to the present invention, there are two parallel holes through which the lead frame is inserted, and the two holes are parallel to the two holes at the surface positions facing each other in the middle part of the two holes. A noise-absorbing bead core having a groove-shaped recess was formed.

[0009]

Since the depression is provided at the surface position corresponding to the middle portion of the two holes, the accuracy of the position and shape of the holes is increased and the accuracy of the pitch length is increased. Further, the extrusion pressure during extrusion molding is made uniform, and the strain during sintering and molding becomes small, so that cracks do not occur during manufacturing or damage due to residual strain does not occur. Furthermore, the depressions provided on the surface facilitate the positioning of the bead core in the packaging operation.

[0010]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT An embodiment of the present invention will be described with reference to FIGS. FIG. 1 (a) is a front view seen from the opening direction of the holes of this embodiment, FIG. 1 (b) is a side view thereof, and FIGS.
FIG. 4A is a front view and a plan sectional view, respectively, which are mounted on a case of this embodiment. The two-hole type bead core 1 has a substantially rectangular parallelepiped shape as a whole, and the front surface thereof has a substantially rectangular shape when viewed from the opening direction of the hole 2. A groove 5 is formed on both surfaces of the rectangular parallelepiped as viewed from the front, that is, in the center of the wide plane of the rectangular parallelepiped in the same direction as the hole 2. Groove 5
Is about 1/4 to 1/5 of the width of a wide plane, and the depth is about the same as the short side of a hole described later. The side wall of the groove 5 has a gentle slope.

Two holes 2 for inserting the lead frame 6 having a rectangular cross section are formed so as to penetrate from the front side to the other side substantially in parallel with the groove 5. The two holes 2 are substantially parallel to each other and are spaced apart from each other with a pitch length 3 which is about three times the long side of the rectangular hole cross section as a space between them, and the two holes 2 extend from the core surface 1a. The distance is equal to or slightly larger than the long side length of the hole cross section.

As shown in FIGS. 2 and 3, the lead frame 6 is inserted into the bead core 1 after being inserted into one hole 2 and then folded back into the other hole 2 in a U shape. When the other bead cores 1 are arranged adjacent to each other, the bead cores 1 are also adjacently inserted into the holes 2 of the other bead core 1 and then folded back into the other holes 2 in a U-shape.

A plurality of bead cores 1 are housed in the case 7. A protrusion 8 and a protrusion 9 are provided on the inner surface of the case 7, the protrusion 8 engages with the groove 5, and the protrusion 9 engages between the two bead cores 1 as a partition.

When the bead core 1 is mounted alone or in a packaged form on a substrate, when the signal on the substrate passes through the lead frame 6, the high frequency unwanted radiation noise contained in the signal causes ferrite bead core 1 to be included in the signal. It is absorbed by and does not radiate to the outside.

With such a structure, if the groove 5 is not provided, the wall thickness of the groove 5 portion becomes the wall thickness 1c 'shown by the length between the two dotted lines in FIG. Although the thickness is very large compared to the wall thickness 1b of the portion, since the groove 5 is provided, the wall thickness of the groove 5 portion is 1c, and the thickness of the hole 2 portion is There is no excessive distortion when the bead core 1 is extruded and then sintered and molded, because it has a slightly larger thickness than the wall thickness 1b and the side surface is an inclined surface, Will not be cracked or damaged by residual strain.

Further, the groove 5 of the bead core 1 can be easily engaged with the projection 8 of the case 7 for positioning during the packaging operation.

Further, the groove 5 of the bead core 1 is bored substantially parallel to the two holes 2 so that the wall thickness around the holes 2 becomes substantially uniform, and is formed by extrusion and during sintering thereafter. Sometimes there is no excessive distortion, the precision of the hole position, shape, etc. improves and the precision of the pitch length increases. Since the pitch length accuracy is high, the high-frequency unwanted radiation noise absorption performance is uniform.

[0018]

According to the present invention, since the depression is provided at the surface position corresponding to the intermediate portion of the two holes, the accuracy of the position and shape of the holes is improved and the accuracy of the pitch length is increased. Therefore, for example, the high-frequency unnecessary radiation noise absorption performance becomes uniform and the quality is improved. Further, the extrusion pressure during extrusion molding is made uniform, and the strain during sintering and molding becomes small, and cracks do not occur during manufacturing, and there is no damage due to residual distortion, so the manufacturing yield is improved. Further, the depressions provided on the surface facilitate the positioning of the bead core in the packaging operation, thus improving workability.

[Brief description of drawings]

FIG. 1 is a front view and a side view seen from the opening direction of a hole according to an embodiment of the present invention.

FIG. 2 is a front view mounted on the case of the embodiment.

FIG. 3 is a plan cross-sectional view mounted on the case of the embodiment.

FIG. 4 is a front view and a side view showing a conventional example.

FIG. 5 is a front view and a plan view showing a conventional example.

[Explanation of symbols]

 1 Bead Core 1a Core Surface 1b, 1c, 1c 'Wall Thickness 2 Hole 3 Pitch Length 5 Groove 6 Lead Frame 7 Case 8 Protrusion 9 Protrusion

Claims (1)

[Claims] 1. A lead frame has two parallel holes through which the lead frame is inserted.
A noise-absorbing bead core having a groove-shaped recess parallel to the two holes.