JP3152363B2 - Surface mount type choke coil - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a small-sized coil, and more particularly to a surface-mounted choke coil mounted on a printed circuit board of a digital device and used for preventing unnecessary radiated electromagnetic noise in an electronic device.

[0002]

2. Description of the Related Art With the digitization and speeding up of signals handled by digital equipment, it is important to cope with signal interference and malfunction due to unnecessary radiated electromagnetic noise generated or received on signal lines and power supply lines. I have. Conventionally, a choke coil in which a ferrite core is passed through a signal line cable between a digital device and a printed circuit board is used as a measure against these problems. Conventionally, in a small toroidal choke coil of this type (hereinafter, referred to as a small choke coil), as shown in FIG. 5, a small diameter toroidal core made of a ferrite material having a high relative magnetic permeability characteristic and a high specific resistance, and a signal line are used. A small choke coil 51 is obtained by winding a copper wire with an insulation coating around the toroidal core. These small choke coils are directly mounted on a printed circuit board after peeling off the insulating coating of the winding terminals, the winding ends 54 are connected to the board terminals 53, and the choke coils are fixed to the board with an adhesive 55. You. There is also a small choke coil which is once housed in a case with a dedicated terminal and mounted on a printed circuit board and connected for convenience of handling.

[0003]

A conventional small-sized choke coil of this type is used for automation, small space, and high-density mounting of a printed circuit board due to digitization of a signal handled by a digital device or the like and high-speed operation. It has a drawback that it cannot sufficiently meet market needs for surface mounting components such as a low profile.

[0004]

SUMMARY OF THE INVENTION The present invention provides a small toroidal choke coil formed by winding an insulated copper wire around a small diameter toroidal core, wherein the toroidal core is attached to a main surface of a thick plate made of an electrically insulating material. It has an annular groove that is deep enough to accommodate it, and has a small choke coil positioning projection at the center, and a flat back surface facing the surface on which the small choke coil is mounted, and a side surface of the main surface. A pin terminal is provided, and the mounting portion of the small choke coil extends from the mounting surface of the small choke coil to the root of the pin terminal, and one of the small choke coils has an appropriate inclination angle from the bottom surface of the annular groove on the main surface. An opening groove provided with a guide groove and an insulating case provided with an opening groove from the middle at right angles to the annular groove on the main surface, and the toroidal coil wound around the toroidal core is connected to the insulation case. The bottom end of the small choke coil is housed in an annular groove, and the bottom side is open from the middle groove, and the top side is perpendicular to the bottom of the annular groove. After being connected to each of the pull-out pin terminals through the groove, the annular groove side of the main surface is set to the lower surface, and the tip of the pin terminal is flattened to the same surface as the main surface by a press machine so as to be surface-mounted so that the surface is mounted. At this time, a surface-mounted choke coil having a flat surface capable of adsorbing a flat surface of the insulating case is used.

That is, the present invention provides a small choke coil in which a coated insulated copper wire is wound around a toroidal core and housed in a resin molded body.
An annular groove having a depth sufficient to accommodate the toroidal core and having a positioning cylindrical projection attached at the center, and a guide having a moderate inclination angle from the bottom surface of the annular groove on one of the winding ends of the annular groove on the side from which the winding end is drawn out. An insulating case having a groove provided therein, the opening extending to the root of a pin terminal planted on both side surfaces of the main surface; and a toroidal coil wound around the toroidal core being formed in an annular groove of the insulating case. After fixing the center hole of the toroidal coil to the positioning cylindrical projection, pulling out the end of the winding through the opening groove and connecting it to the pin terminal, the main surface annular groove is placed on the lower surface, and the tip of the pin terminal is placed. A surface-mounted choke coil characterized by being formed flat on the same surface as the main surface.

[0006]

An annular groove for inserting a toroidal coil having a positioning cylindrical projection for inserting and positioning a central hole of the toroidal coil in the center is provided, and one of the annular grooves is shaped into a shape inclined from the bottom surface to a slope. In the insulation case, the other end is provided with a pin terminal on the end face where the opening groove is attached. After solder connection to the terminal, the top of the component is sucked by the suction pad by forming the tip of the pin terminal into a surface mountable shape with the opening side with the annular groove of the insulating case facing down Then, a surface mount type choke coil that can be mounted by an automatic machine is used.

[0007]

FIG. 1 is a perspective view of a completed appearance of one embodiment of a surface mount type choke coil according to the present invention, and FIG. 2 is a perspective view of a toroidal coil having a toroidal core used in the present invention and a coated insulated copper wire wound by bifilar. FIG. 3 is an external perspective view of an insulating case for surface mounting used in the present invention, and FIG. 4 is a perspective view of the insulating case for surface mounting shown in FIG.
FIG. 2 shows a cross-sectional view taken along line A. The insulating case 31 is a rectangular thick plate made of an electrically insulating material, and has on its surface a suction flat surface 36 for the automatic mounting machine to suck the insulating case, and FIG. 3 shows the toroidal coil shown in FIG. An annular groove 32 having a depth dimension sufficient for storage and having at the center thereof a positioning cylindrical projection 33 for positioning and sandwiching between the inner wall of the annular groove and the central hole of the toroidal coil 21 is formed. A pair of opening grooves 34 are formed in the case side surfaces, each of which is open to both end surfaces through the annular groove 32. The depth of one of the opening grooves 34 is a depth sufficient to accommodate the thickness of the winding end 24 of the toroidal coil and a depth reaching the root of the outer pin terminal 37. The other has a depth reaching the root of the external pin terminal 37 as shown in FIG. 4, and a portion communicating with the annular groove 32 has a depth higher than the thickness of the toroidal coil. A guide groove 35 having an appropriate inclination angle and leading to the opening groove is provided. Further, external pin terminals 37 (for example, having a diameter of 0.6 mm and a thick plate of 0.3 mm) extending horizontally from the side surface of the case are implanted so as to connect the roots to the open grooves 34 on both sides of the insulating case.

Next, the surface mount type choke coil of the present invention will be described. A toroidal coil 21 as shown in FIG. 2 is obtained by winding a winding 23 of a coated insulated copper wire in which two conductors are parallel to, for example, a bifilar winding around a Ni-Zn-based small-diameter toroidal core 22 having high relative magnetic permeability characteristics. . For example, the outer diameter of the toroidal core is φ4 mm and the wire diameter is φ0.1 m
/ M single line or parallel line. The center hole of the toroidal coil 21 formed by applying a winding inside the annular groove 32 of the insulating case 31 shown in FIG.
3, the winding end 24 is drawn out of the insulating case 31 through the opening groove 34, and wrapped around the pin terminal 37. At this time, the bottom of the toroidal coil at the winding end 24 of the toroidal coil 21 which is drawn out from the bottom of the winding passes through the guide groove 35 provided at an inclination angle from the bottom of the annular groove shown in FIG. After that, it is tied to the root of the pin terminal 37. For soldering, several pin terminals 37 of the insulating case 31 are collectively held in a wire jig (for example, by a magnet or the like, or clamped by a spring force), and then immersed in a molten solder bath for several seconds. At the same time as the insulating film on the winding end 24 is thermally peeled off, it is soldered and connected to the pin terminal 37. For example, when forming the pin terminal 37 into a gull-wing shape, the structure of the press die is a relatively simple die that holds the case holding portion, the terminal pressing portion, the terminal bent portion, and the like with a spring force. Terminal bending and terminal cutting can be processed in one operation process. Inspection of relatively simple inductance, DC resistance, etc., inspection of terminal bending dimensions, etc.
Check performance.

[0009]

The present invention relates to a small choke coil formed by winding an insulated copper wire around a small diameter toroidal core.
On the main surface of a thick plate made of an electrically insulating material, an annular groove having a depth sufficient to accommodate the toroidal core is provided, and a centering cylindrical projection for positioning the toroidal coil is provided at the center thereof, and the toroidal coil is mounted. The back surface with respect to the opening surface to be formed has a flat surface, has a pin terminal implanted on the side surface of the opening surface, extends to the root of the pin terminal, and has one side from the bottom surface of the main surface annular groove. An insulating case having an opening groove provided with an appropriate inclination angle, a toroidal coil wound on the toroidal core is housed in an annular groove of the insulating case, and an end of the winding is pulled out to the pin terminal through the opening groove. After the connection, the tip of the pin terminal is formed into a shape that can be surface-mounted by a press machine, with the annular groove on the opening side being the lower surface so that the annular groove on the main surface is the lower surface. A surface-mounted choke coil that has a flat surface that can be attracted by an automatic mounting machine such as a printer and that does not impair the magnetic characteristics of the toroidal coil that forms a small choke coil because the toroidal coil is not sealed with resin or the like. Get.

[Brief description of the drawings]

FIG. 1 is a perspective view of a completed appearance of an embodiment of a surface-mount type choke coil according to the present invention.

FIG. 2 is an external perspective view of a toroidal coil in which a bifilar winding is applied to a toroidal core used in the present invention.

FIG. 3 is an external perspective view of an insulating case for surface mounting used in the present invention.

FIG. 4 is a sectional view taken along line AA of the insulating case for surface mounting shown in FIG. 3;

FIG. 5 is an external perspective view showing a conventional small choke coil.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 21 Toroidal coil 22 Toroidal core 23 Winding 24, 54 Winding end 31 Insulating case 32 Annular groove 33 Positioning cylindrical projection 34 Opening groove 35 Guide groove 36 Suction plane 37 Pin terminal 51 Choke coil 53 Substrate terminal 55 Adhesive

Claims (1)

(57) [Claims] 1. A small choke coil formed by winding an insulated copper wire around a toroidal core and enclosing the insulated copper wire in a resin molded body, wherein the choke coil is sufficient to accommodate the toroidal core on a main surface of a thick plate made of an electrically insulating material. At an appropriate depth, an annular groove with a positioning cylindrical projection attached at the center and an opening groove with a guide groove with an appropriate inclination angle from the bottom of the annular groove on one of the winding ends of the annular groove on the side where the winding end is drawn out are attached. An insulating case in which the opening groove extends to the roots of the pin terminals implanted on both side surfaces of the main surface, and a toroidal coil wound on the toroidal core, and a central hole of the toroidal coil positioned in an annular groove of the insulating case. After attaching and fixing to the cylindrical projection for use, drawing out the end of the winding through the opening groove and connecting to the pin terminal, the main surface annular groove is placed on the lower surface, and the tip of the pin terminal is flush with the surface of the main surface. Flat A surface mount type choke coil characterized by being formed.