JP3655517B2 - Pot rivet type core surface mount choke coil - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a pot rivet type core surface mount choke coil, and more particularly, a pot rivet type core using a pot rivet type core that is a combination of a pot type core and a rivet type core as a coil core and having improved DC current superposition characteristics. The present invention relates to a surface mount choke coil.
[0002]
[Prior art]
A conventional example of a surface mount choke coil will be described with reference to FIGS. FIG. 3A is a perspective view of a surface-mounted choke coil, and FIG. 3B is a view showing a height-direction cross section along line bb ′ in FIG. FIG. 4 is an exploded perspective view of the surface mount choke coil of FIG.
3 and 4, 1 is a ring core, 2 is a drum core, 3 is a winding, and 4 is a terminal. The ring core 1 and the drum core 2 are made of ferrite which is an electrically insulating material. The side surface of the ring core 1 is formed with a pair of flat portions 12 opposed to each other. A circular arc surface portion 13 that faces each other and is adjacent to the pair of flat surface portions 12 has a notch 11 formed at the lower end portion thereof.
[0003]
The drum core 2 includes a pair of flange portions 21 and a flange core portion 22 that is integrally coupled to the flange portions 21 and connects the two. A pair of flat portions 211 facing each other is formed on a part of the both flange portions 21. The coil 3 is formed by winding the winding 3 around the core portion 22 of the drum core 2.
The terminal 4 is cut and raised as a terminal core fixing portion 41 at the center thereof. One end of the terminal 4 is bent slightly in the same plane with the tip of the terminal body to be a carragage solder portion 42, and the other end is bent at a right angle to form a rising portion 43.
[0004]
The ring core 1, drum core 2, winding 3, and terminal 4 are manufactured and prepared. Here, referring to FIG. 4 (b), the terminal 4 is bonded and fixed to the surface of the one flange portion 21 of the drum core 2 by a thermosetting adhesive such as an epoxy resin via the terminal core fixing portion 41. In this case, the rising portions 43 of the terminals 4 are opposed and fixed to the flat portions 211 of the both flange portions 21 of the drum core 2 in parallel with each other. 4C, the winding 3 is wound around the core portion 22 of the drum core 2 configured as shown in FIG. 4B. Then, both ends of the winding 3 are carraged to the carragage solder portion 42 of the terminal 4. In a state where the end of the winding 3 is carraged to the carragage solder portion 42 of the terminal 4, reflow soldering is applied to the carragage solder portion 42 to completely connect the terminal 4 and the winding 3 electromechanically. .
[0005]
The ring core 1 is fitted to the drum core 2, the winding 3, and the terminal 4 assembled as described above. When fitting the ring core 1, the notch 11 at the lower end of the circular arc surface portion 13 of the ring core 1 is opposed to the carragage solder portion 42, and the lower end of the flat surface portion 12 is made to correspond to the rising portion 43 of the terminal 4 and fitted together. To do. The carragage solder portion 42 of the terminal 4 is bent after soldering, but the notch 11 constitutes an accommodation area for the bent carragage solder portion 42. Since the drum core 2 including the winding 3 is covered with the heat shrinkable tube and accommodated in the ring core 1, the gap 5 is substantially filled with the heat shrinkable tube.
[0006]
[Problems to be solved by the invention]
The surface mount choke coil using the drum core 2 and the ring core 1 has a limit in electrical characteristics, that is, superposition characteristics. The choke coil is operated and used in a state where a DC bias voltage is applied when the choke coil is operated. However, since the core is made of a magnetic material, it naturally approaches magnetic saturation as the DC bias voltage is increased, and the inductance of the coil decreases. Therefore, the DC bias voltage applied to the choke coil cannot be increased without limit, and there is a certain limit.
[0007]
The assembly of the surface mount choke coil described above requires a large number of work steps and takes a long time for all manufacturing steps. That is, the (first) terminal 4 is bonded and fixed to the surface of one flange portion 21 of the drum core 2 through a terminal core fixing portion 41 with a thermosetting adhesive such as an epoxy resin. Next, the winding 3 is wound around the core portion 22 of the (second) drum core 2. Then, (3rd) both winding ends of the winding 3 are carraged to the carragage solder portion 42 of the terminal 4. (Fourth) Reflow soldering is applied to the carragage solder portion 42 in a state where the end portion of the winding 3 is carragled to the carragage solder portion 42 of the terminal 4, and the terminal 4 and the winding 3 are electromechanically connected. To do. (Fifth) The ring core 1 is fitted to the drum core 2, the winding 3, and the terminal 4 assembled as described above. (Sixth) The carragage solder portion 42 of the terminal 4 is bent after soldering. The above 6 steps are required.
[0008]
In addition, when a surface-mounted choke coil is manufactured by purchasing and using a ready-made rectangular electric wire, the cost of the surface-mounted choke coil is increased.
The present invention provides a pot rivet type surface mount choke coil which solves the above-mentioned problems.
[0009]
[Means for Solving the Problems]
A first embodiment of the present invention provides a pot-type core 10 composed of a top wall 101 and a side wall 103 integrally formed with the top wall 101, and a bottom plate 201 and a magnetic core portion standing upright at the center of the bottom plate 201. The rivet type core 20 is composed of a coil 3 fitted to the magnetic core portion 204 of the rivet type core 20, and the upper end surface of the magnetic core portion 204 is attached to the lower surface of the top wall 101 of the pot type core 10. Adjacently facing each other to form a magnetic path gap , an epoxy synthetic resin adhesive is applied to the opening peripheral end surface of the pot-type core 10 and the surface of the bottom plate 201 of the rivet-type core 20 so that the pot-type core 10 and the rivet-type core 20 In the pot rivet type core surface mount choke coil,
Coil 3 is intended to be deformed the rectangular copper wire formed by cutting the electric copper helically formed by winding the rectangular electric wire constructed by applying insulating material film on the surface, a rivet-type core 20 is provided with a terminal 4 fixed to the bottom plate 201 and connected to the coil 3, and this terminal 4 has a U-shaped mounting portion 44 composed of an upper piece, a lower piece, and a connecting portion for coupling the two pieces, A coil connection portion 45 that is bent from the upper piece of the attachment portion 44 to the same side as the upper piece in a coplanar state with the upper piece, and is integrally extended, and this coil connection It is composed of a pair of locking projections 46 formed to project upward from the portion 45,
The bottom plate 201 of the rivet-type core is formed with a terminal placement surface 203 having a step difference as low as the thickness of the terminal 4 on the surface, and a step is formed on the bottom plate lower surface corresponding to the terminal placement surface 203. The fitting thin wall portion 202,
The terminal 4 constituted a pot rivet type core surface mounting choke coil in which the coil connecting portion 45 was placed on the terminal placement surface 203 and the attachment portion 44 was fitted and fixed to the fitting thin portion 202 .
[0010]
DETAILED DESCRIPTION OF THE INVENTION
A reference example of the present invention will be described with reference to FIGS. FIG. 1 is an exploded perspective view of a reference example , (a) is a perspective view of a pot-type core, (b) is a perspective view of a flat coil, and (c) is a perspective view of a rivet-type core and terminals. 2A and 2B are views showing the assembled choke coil, in which FIG. 2A is a perspective view thereof, and FIG. 2B is a view showing a longitudinal section along line bb ′ in FIG. 1 and 2, members that are the same as those in FIGS. 3 and 4 are given the same reference numerals.
[0011]
Reference numeral 10 denotes a pot type core made of ferrite. Reference numeral 101 denotes a top wall of the square pot-type core 10, and a through hole 102 is formed at the center thereof. Reference numeral 103 denotes a side wall of the pot-type core 10. A notch 104 is formed in a lower corner portion where the side walls 103 adjacent to each other intersect.
The pot type core 10 is filled with pressure and molded with ferrite fine powder in a mold. The pressure-molded body of the pot-type core 10 made of the ferrite fine powder is then fired at a high temperature to form the ferrite pot-type core 10.
[0012]
Reference numeral 3 denotes a coil. In the reference example of FIG. 1, the coil 3 is configured by winding a rectangular electric wire in particular. The flat electric wire coil 3 is configured by deforming a flat copper wire into a spiral shape. Reference numeral 31 denotes a coil terminal portion. The rectangular electric wire coil 3 is formed by helically deforming a rectangular copper wire formed by cutting an extremely thin electric copper plate and applying an insulating material coating on the surface. Here, the flat electric wire coil 3 is formed by winding about 4 turns. And the coil 3 can generally be formed by winding a round cross section or a square electric wire.
[0013]
4 is a terminal. The terminal 4 includes a mounting portion 44 having a U-shaped cross section, a coil connecting portion 45 that is integrally extended from the mounting portion 44, and a locking projection 46 that is formed to protrude from the upper surface of the coil connecting portion 45.
Reference numeral 20 denotes a rivet type core made of ferrite. The rivet-type core 20 includes a square bottom plate 201 and a magnetic core portion 204 that stands integrally with the bottom plate 201 at the center thereof. Reference numeral 202 denotes a fitting thin portion formed at an intermediate portion between two opposing sides of the bottom plate 201, and the U-shaped attachment portion 44 of the terminal 4 is fitted and fixed. Reference numeral 203 denotes a terminal mounting surface, which corresponds to the plate thickness of the terminal 4 and is a region having a step that is lower than the surface of the bottom plate 201 by this thickness.
[0014]
The rivet-type core 20 is also formed by integrally filling and pressing the ferrite fine powder into the mold and molding the magnetic core portion 204 and the bottom plate 201 together. The press-molded rivet core made of the fine ferrite powder is then fired at a high temperature to form the rivet core 20.
The order of assembling the choke coil using the above components will be described.
A pot type core 10, a rectangular electric wire coil 3, a terminal 4, and a rivet type core 20 are prepared.
[0015]
(First) The terminal 4 is fitted and fixed to the terminal mounting surface 203 and the fitting thin portion 202 of the rivet type core 20. (Second) The rectangular electric wire coil 3 is fitted to the magnetic core portion 204 of the rivet type core 20. (Third) The coil terminal portion 31 of the rectangular electric wire coil 3 is soldered to the coil connection portion 45 of the terminal 4. At this time, the coil connection portion 45 of the terminal 4 is temporarily engaged with the locking projection 46 formed to protrude from the upper surface of the coil connection portion 45. (Fourth) An epoxy-based synthetic resin adhesive is applied to the opening peripheral end face of the pot-type core 10 and the surface of the bottom plate 201 of the rivet-type core 20. (Fifth) In a state where the magnetic core portion 204 of the rivet type core 20 is inserted into the through hole 102 of the pot type core 10, the two are joined and fixed.
[0016]
This completes the assembly of the choke coil.
As an example, the size of the pot rivet type core surface mount choke coil is as follows. The height of the side wall 103 is 3.8 mm, the height of the notch 104 is 1 mm, and the thickness of the metal thin plate material of the terminal 4 is 0. 4 mm, the thickness of the bottom plate 201 is 1.7 mm, and the step from the surface of the bottom plate 201 is about 0.4 mm.
In the previous reference example , a through-hole 102 is formed in the center portion of the top wall 101 of the pot-type core 10, and penetrates the magnetic core portion 204 that stands integrally with the bottom plate 201 of the rivet-type core 20. A gap of a magnetic path is formed through the hole 102. Here, the embodiment will be described with reference to FIG. 6. In the embodiment, the same reference numerals are given to the members common to the constituent members in the reference example. In this embodiment, the pot-type core 10 does not have the through-hole 102 formed in the top wall 101 and is opened only at the lower peripheral edge. A magnetic path gap is formed by making the upper end surface of the magnetic core portion 204 erected at the center of the rivet-type core 20 face each other close to the lower surface of the top wall 101 of the pot-type core 10. In the case of this embodiment, the rectangular electric wire coil 3 is sealed in a space formed by the pot-type core 10 and the rivet-type core 20, and almost no leakage magnetic flux is generated.
[0017]
As described above, the direct current superposition characteristics of the surface mount choke coil can be improved by configuring the core of the surface mount choke coil with the pot rivet core that is a combination of the pot type core and the rivet type core. This is shown by the experimental results as shown in FIG. FIG. 5A is a diagram showing a direct current-inductance characteristic curve of an experimental example of a surface mount choke coil using a core composed of a ring core and a drum core. FIG. 5B is a diagram showing a DC current-inductance characteristic curve of an experimental example of a surface mount choke coil using a pot rivet core in which a pot core and a rivet core are combined. The outer dimensions of each choke coil are products having a rated inductance of 10 μH and a vertical and horizontal dimensions of 12.5 mm and a height of 5.5 mm. The measurement was performed at room temperature of 25 ° C.
[0018]
In the conventional example of FIG. 5 (a), the characteristics suddenly deteriorate when the superimposed DC current slightly exceeds 4.0A. However, in the embodiment of FIG. 5 (B), the rated DC current is about 10 μH up to about 7.0A. It is shown that it can be put to practical use as a product. Comparing the experimental example of the conventional example with the experimental example of the example, the DC current superposition characteristic is improved by about 3.0 A.
And when looking at the number of assembly process steps for surface mount choke coils, this invention seems to be slightly reduced from the conventional 6 steps to 5 steps. Thus, it can be easily understood how the individual work contents of the present invention are simplified and the assembly work time is shortened.
[0019]
In addition, as the electric wire constituting the coil 3, in particular, by using a rectangular electric wire in which a rectangular copper wire having a rectangular cross section formed by cutting a very thin electric copper plate is coated with an insulating material, a surface-mounted choke coil The internal resistance can be reduced. That is, a commercially available flat electric wire has an oval cross-sectional shape, whereas a flat electric wire constituted by the above manufacturing process has a rectangular cross-sectional shape, and this cross-sectional shape is a rectangular electric wire. The proportion of the cross-sectional area of the rectangular electric wire itself in the coil cross-sectional area when the coil is configured can be almost 100%. This is advantageous for reducing the internal resistance of the surface mount choke coil and increasing the rated current of the surface mount choke coil. And, compared with the case of purchasing a commercially available flat electric wire and thereby forming a flat electric wire coil, it is cheaper to construct a flat electric wire coil by this invention to about 1/3. Can be This contributes to a reduction in the manufacturing cost of the entire surface mount choke coil.
[0020]
Furthermore, the through-hole 102 is not formed in the top wall 101 of the pot-type core 10, but only the peripheral edge at the lower end is opened, and the flat electric wire coil 3 is sealed in a space formed by the pot-type core 10 and the rivet-type core 20. By adopting the configuration, almost no leakage magnetic flux is generated.
[0021]
【The invention's effect】
As described above, by configuring the core of the surface-mounted choke coil with a pot rivet-type core that is a combination of a pot-type core and a rivet-type core, the direct current superposition characteristics of the surface-mounted choke coil can be improved.
By adopting a configuration in which the coil is sealed in a void formed by a pot-type core and a rivet-type core, a surface-mounted choke coil with very little leakage magnetic flux can be obtained.
[0022]
Further, by adopting the above pot rivet type core, the contents of the assembly work can be simplified and the assembly work time can be shortened.
Further, by adopting a rectangular electric wire coil as the electric wire constituting the coil, the internal resistance of the surface mount choke coil can be reduced and the manufacturing cost of the entire surface mount choke coil can be reduced.
[Brief description of the drawings]
FIG. 1 is an exploded perspective view of a reference example .
FIG. 2 is a view showing a reference example of the assembled choke coil.
FIG. 3 is a perspective view of a conventional example.
4 is an exploded perspective view of the conventional example of FIG. 3. FIG.
FIG. 5 is a diagram for explaining DC current superposition characteristics;
6 is a diagram for explaining an embodiment.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 10 Pot type core 101 Top wall 102 Through-hole 103 Side wall 104 Notch part 20 Rivet type core 201 Bottom plate 202 Fitting thin part 203 Terminal mounting surface 204 Magnetic core part 3 Coil 31 Coil terminal part 4 Terminal 44 Attachment part 45 Coil connection Part 46 Locking projection

Claims (1)

It has a top wall and a top wall and a pot type core consisting integrally formed sidewall having a rivet-type core made of magnetic core provided upright on the bottom plate and the bottom plate integrally with the center portion, rivet Having a coil fitted to the magnetic core portion of the mold core, the upper end surface of the magnetic core portion is closely opposed to the lower surface of the top wall of the pot core to form a magnetic path gap, In the pot rivet type core surface mount choke coil in which an epoxy synthetic resin adhesive is applied to the end surface and the surface of the bottom plate of the rivet type core, and the pot type core and the rivet type core are bonded and fixed,
The coil is formed by winding a rectangular wire formed by cutting a flat copper wire formed by cutting an electric copper plate into a spiral shape and applying an insulating material coating on the surface,
A terminal fixed to the bottom plate of the rivet-type core and connected to the coil is provided, and this terminal has a U-shaped mounting section composed of an upper piece, a lower piece, and a connecting portion that couples both, and From the upper piece, it is bent in the shape of a dogleg to the same side as the upper piece in the coplanar state with the upper piece, and a coil connecting portion that is integrally extended and protrudes upward to the coil connecting portion Consisting of a pair of locking projections formed,
The bottom plate of the rivet core is formed with a terminal mounting surface having a level difference as low as the thickness of the terminal on the surface, and a step is formed on the bottom surface of the bottom plate corresponding to the terminal mounting surface to form a thin fitting portion age,
A pot rivet-type core surface-mounted choke coil characterized in that the terminal has a coil connection portion placed on the terminal placement surface, and the attachment portion is fitted and fixed to the fitting thin wall portion .

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