JPH03125413A - Small-size choke coil and its manufacture - Google Patents

Abstract

PURPOSE:To facilitate the positioning of terminal area materials and obtain small-size choke coils suitable for mass production without spoiling the magnetic characteristics, by letting fixed part materials have protrusions which touch a bead core, and tapered sections provided at their one-sided ends. CONSTITUTION:At first, a lead frame and a plurality of terminal area materials 23 are processed and manufactured in one united body. Fixed part materials 28 are held with a plurality of terminal area materials 23 by the use of electrically insulating resin. On that occasion, terminal area materials 23, small protrusions 29a, 29b, protruded segments 30, and tapered sections 35 are provided at the fixed part materials 28. Next, a support frame 26A is cut off. Then, a plurality of terminal area materials 23 made in one united body with a support frame 26B are pressed and inserted into through holes 22 from arrowheadlike sections 32. Lastly, the support frame 26B is removed. In this way, it becomes possible to guide and insert a plurality of terminal area materials 23 all together into the through holes 22 of a bead core 21. Accordingly, it becomes possible to fix them easily and accurately.

Description

[Detailed Description of the Invention] [Industrial Application Fields] The present invention provides a small choke coil that is mounted on a printed circuit board used in digital equipment to prevent unnecessary radiation noise in electronic equipment, and a method for mass producing the same. Regarding.

[Prior art] Conventionally, this type of small choke coil is shown in Figs. 10 to 12.
As shown in the figure, the structure includes a plurality of through holes 6
2, and a plate-shaped terminal member 63 that penetrates through the plurality of through holes 62 and protrudes to the outside of the bead core 61. The terminal member 63 is a conductive metal plate subjected to surface treatment such as solder plating. After the terminal member 63 is inserted into the bead core 61, the entire bead core 61 into which the terminal member 63 has been inserted is sealed with a sealing molded portion 64 made of electrically insulating resin such as EP. During the sealing process, a plurality of terminal members are positioned respectively.

This type of small choke coil is mounted on a board 65 by soldering a terminal member 63 to a circuit pattern 66 on the board 65, as shown in FIG.

[Problems to be Solved by the Invention] However, when the entire bead core is sealed and molded, the terminal member tends to be misaligned, resulting in a serious drawback in that the magnetic properties are impaired.

SUMMARY OF THE INVENTION Accordingly, a technical object of the present invention is to provide a small choke coil and a method thereof that are suitable for mass production and that facilitate the positioning of terminal members and do not impair magnetic properties.

[Means for Solving the Problems] According to the present invention, a small-sized bead core made of a Ni-Zn ferrite material and having a through hole, and a terminal member that penetrates the through hole and projects to the outside of the bead core. The choke coil includes a fixing member held by the terminal member and inserted into the through hole, the fixing member having a protrusion that comes into contact with the bead core and a tapered part provided at one end of the protrusion. A small choke coil with the following characteristics can be obtained.

Moreover, in this small-sized choke coil, a small-sized choke coil is also obtained, characterized in that the resin contains at least 30% by volume of Ni-Zn-based ferrite material.

In the method of manufacturing these small choke coils,
a step of integrally manufacturing the terminal member with a lead frame at one end thereof; a step of holding the fixing member around the terminal member; a step of providing the tapered portion at an end located on the opposite side to one end; and a step of press-fitting the terminal member and the fixing member into the through hole with the tapered portion at the beginning and fixing them to the bead core. There is obtained a method for manufacturing a small choke coil characterized by including the following.

[Example] Hereinafter, a small choke coil according to an example of the present invention will be described with reference to the drawings.

Referring to FIGS. 1(a), (b), and FIG. 2, the small choke coil according to the first embodiment includes a bead core 21 having a through hole 22, and a bead core 21 that passes through the through hole 22 to the outside of the bead core 21. It has a terminal member 23 that protrudes.

The bead core 21 is made of a Ni-Zn ferrite material. The bead core 21 has at least one flat surface, and usually has an outer diameter in the longitudinal direction of 1 to 7.
+on+. The radius of the inner peripheral surface of the through hole 22 is 0.3-
The length is 0.6 mm and the length is about 1 to 10 mm.

FIG. 3 shows a plurality of terminal members 23 having both ends integrated with a lead frame (support frame 26A1 and lead frame 26B).

The terminal member 23 is made of stainless steel, copper-iron alloy, phosphor bronze,
It consists of a metal plate made of magnetic material such as N42 or N52 alloy.

By performing precision sheet metal processing, photoetching, etc., a product having a shape in which a plurality of terminal members 23 integrated with a lead frame are arranged at predetermined intervals as shown in FIG. 3 is manufactured.

Each terminal member 23 has a bevelled portion 32, a small protrusion 24, and a minute hole 31. The beveled portion 32 is adjacent to the support frame 26A and has a beveled shape so that the support frame 26A can be easily removed.

The protrusion 24 and the minute hole 31 are provided in the center of the terminal member 23.

Referring to FIG. 4 in addition to FIG. 1, a fixing member 28 made of electrically insulating resin is molded around the terminal member 23 and held therein. At this time, the electrically insulating resin flows into the microholes 31 and hardens.

Therefore, since the fixing member 28 engages with the protrusion 24 and the microhole 31, it is firmly held with respect to the terminal member 23. Furthermore, by including at least 30% by volume of Ni-Zn ferrite material in the fixing member 28 made of electrically insulating resin, the terminal member 23 can be easily fixed to the bead core 21. PPS and ABS are electrically insulating resins.
, EP, etc. are used.

The fixing member 28 includes protrusions 29a, 29b, a protrusion 30,
and a tapered portion 35 are provided. The protrusions 29a and 29b are pressed against the inner peripheral surface of the through hole 22 when the terminal member 23 is inserted into the through hole 22 of the bead core 21. The projecting piece 30 projects like a flange from the end on the support frame 26A side. Insertion of the terminal member 23 into the through hole 22 is prevented by the projection piece 30 coming into contact with the end surface of the bead core 21 . That is,
The projecting piece 30 is for determining the position of the terminal member 23. The tapered portion 35 is provided at the end on the support frame 26B side and guides insertion of the bead core 21 into the through hole 22.

Next, a method for manufacturing the small choke coil of Example 1 will be described.

As shown in FIG. 3, first, the lead frame and the plurality of terminal members 23 are processed and manufactured as one body.

Referring to FIG. 4, the plurality of terminal members 23 are made of electrically insulating resin to hold the fixing member 28.

At that time, the small protrusion 29a is attached to the terminal member 23 on the fixing member 28.
, 29b, a protruding piece 30, and a tapered portion 35 are formed.

Next, the support frame 26A is cut out.

A plurality of terminal members 23 integrated with the support frame 26B are press-fitted into the through-hole 22 from the beveled portion 32.

As a result, each protruding piece 30 comes into contact with one end of the bead core 21. In addition, the small projections 29a, 29b of each fixing member 28
is pressed against the inner peripheral surface of the through hole 22 of the bead core 21.

Finally, the support frame 26B is removed.

In this way, the plurality of terminal members 23 can be inserted and guided into the through hole 22 of the bead core 21 all at once, and can be easily and precisely fixed.

Further, when mounting a digital device onto a printed circuit board, the digital device is generally mounted by suction using a suction device of a mounting machine. In the present invention, the flat surface of the bead core 21 can be sucked by the suction device of the mounting machine, and the mounting work can be easily automated.

Referring to FIG. 9, the relationship between frequency f and impedance Z is illustrated. According to this, it can be seen that the magnetic properties 11 of the small choke coil of Example 1 are superior to the magnetic properties 12 of the conventional small choke coil.

Incidentally, when the entire small choke coil of Example 1 is sealed and molded with resin, the magnetic characteristic becomes 13, and the magnetic characteristics 11 and 13 show similar characteristics. Therefore, since it is the same whether or not it is sealed, a compact choke coil that is superior to the conventional one can be obtained.

A second embodiment of the present invention will be described below with reference to the drawings.

The differences between the small choke coils of Examples 1 and 2 will be described.

With reference to FIGS. 5(a), (b) and FIG. 6, Example 2
In this case, the bead core 21 has one through hole 22.

Referring to FIG. 7, in the second embodiment, the protrusion 24 is not provided with a microhole.

Referring to FIG. 8, the fixing member 28 has a tapered portion 35, a protruding piece 30, and a small protruding portion 29. As shown in FIG.

As shown in the figure, the fixing member 28 covers a plurality of (seven in the figure) terminal members 23 except for both ends. Note that the tapered portion 35 has a taper t.

The protruding piece 30 is provided so as to protrude in a direction perpendicular to the longitudinal direction of the terminal member 23. When inserting the tapered portion 35 into the through hole 22 of the bead core 21, the protruding piece 3
0 and the bead core 21 come into contact with each other to perform positioning.

Two small protrusions 29 are provided on each side of the tapered portion 35. The two small protrusions 29 on each surface of the tapered portion 35 have an appropriate interval in a direction perpendicular to the longitudinal direction of the terminal member 23.

It should be noted that the same magnetic properties as the small choke coil of Example 1 (
FIG. 9) can also be obtained in Example 2.

[Effects of the Invention] As explained above, according to the present invention, the terminal member can be positioned well, the fixing member can strongly fix the terminal member and the bead core, and the bead core can be sealed as in the past. The present invention has the advantage that not only the magnetic properties are not impaired due to fixed molding, but also a small choke coil and a method thereof suitable for mass production can be obtained.

[Brief explanation of drawings]

FIG. 1(a) is an external view of a small choke coil according to Example 1 of the present invention, FIG. 1(b) is a sectional view of FIG. 1(a), and FIG.
The figure shows the bead core of the small choke coil in Fig. 1(b), and Fig. 3 shows multiple terminal members integrated with the lead frame used in the small choke coil in Fig. 1(b). 4(a) is a diagram showing that electrically insulating resin is molded onto the terminal member shown in FIG. 3, and FIG. 4(b) is a diagram showing that the
5(a) is a diagram showing a plurality of terminal members having small terminal members and integrated with a lead frame; FIG. 5(a) is an external view of a small choke coil according to Example 2 of the present invention; 5
Figure (b) is a cross-sectional view of Figure 5 (a), and Figure 6 is a cross-sectional view of Figure 5 (b).
7 is a diagram showing the bead core of the small choke coil in Figure 5(b), and Figure 8(a) is a diagram showing a plurality of terminal members integrated with the lead frame used in the small choke coil in Figure 5(b). ) is a diagram showing that the terminal member in Figure 7 is molded with electrically insulating resin, and Figure 8 (b) is a smaller terminal member in Figure 8 (a), which is integrated with the lead frame. Figure 9 is a diagram showing the magnetic characteristics of the relationship between frequency and impedance; Figure 10 is an external view of an example of a conventional small choke coil; Figure 11 is a diagram of a conventional small choke coil. FIG. 12 is an external view showing the other side of the coil mounted on a board, and FIG. 12 is a cross-sectional view of the small choke coil shown in FIG. 11. 1] ... Magnetic characteristics of the small choke 2 of Examples 1 and 2 of the present invention before the entire coil is sealed and molded with resin, 12.
...Magnetic characteristics of conventional small choke coils, 13...
Magnetic properties after the small choke coil of the present invention is sealed and molded with resin, 21... Bead core, 22... Through hole,
23... Terminal member, 24... Projection, 25... Positioning hole, 26A, 26B... Support frame, 28...
...Fixing member, 29.29a, 29b...small protrusion,
30... Protruding piece, 31... Microhole, 32... Pointed part, 35... Taper part, 63... Terminal member, 64
... Sealing IF molding part, 65... Board, 66... Circuit pattern. 3 Figure 1 ((1) (b) Figure 2 Figure 3 Figure 5 (a) (b) Figure 6 Figure 7 Figure 9 Figure 10 Su, 3 Figure 11 Suzu

Claims (1)

[Scope of Claims] 1) A small choke coil having a bead core made of Ni-Zn ferrite material having a through hole, and a terminal member penetrating the through hole and projecting to the outside of the bead core. The compact device includes a fixing member held by the terminal member and inserted into the through hole, the fixing member having a protrusion that comes into contact with the bead core, and a tapered part provided at one end of the fixing member. choke coil. 2) The small choke coil according to claim 1, wherein the fixing member contains at least 30% by volume of Ni-Zn ferrite material. 3) A method for manufacturing a small choke coil according to claim 1, including the steps of integrally manufacturing the terminal member with a lead frame at one end thereof, holding the fixing member around the terminal member, and fixing the terminal member. providing a member with the protrusion and the tapered part at an end located on the opposite side of the protrusion from the one end of the terminal member; and fixing the terminal member and the fixing with the tapered part at the beginning. A method for manufacturing a small choke coil, comprising the step of press-fitting a member into the through hole and fixing it to the bead core.