JP2004022812A - Coil component for printed coil fixed on printed circuit board - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a coil component excellent in characteristics for a printed coil, fixed on a printed circuit board. <P>SOLUTION: A soft magnetic core 3 is inserted to a through hole 2 formed in a printed circuit board 1 and a printed coil 4 is formed spiral on the printed circuit board 1 surrounding the through hole 2. An innermost turn of the printed coil 4 is formed at a distance d from the through hole 2, which can ensure electrical insulation between the core 3 and the printed coil 4. <P>COPYRIGHT: (C)2004,JPO

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a coil component such as a thin transformer or a choke coil used for an electronic device or a power supply device, and more particularly to a printed coil type coil component employing a printed coil as a coil.
[0002]
[Prior art]
2. Description of the Related Art Among coil components such as a transformer and a choke coil, a printed coil type coil component including a printed coil in which a printed coil is formed in a spiral shape on a printed board around a through hole of the printed board through which a core is inserted is known. .
[0003]
[Problems to be solved by the invention]
Among these types of printed coil type coil components, those requiring a large inductance have the problem that the diameter of the coil increases as the number of turns increases, the space occupied by the printed circuit board increases, and the device size increases. there were. For this reason, in a conventional print coil type coil component fixed to a printed circuit board, an increase in the diameter of the print coil is suppressed by providing the innermost turn of the print coil in contact with the core insertion hole. Further, a printed circuit board having a multi-layered conductor layer is used to form a multi-layered printed coil to suppress an increase in the diameter of the printed coil.
[0004]
However, in this case, it has been found that the creeping electric resistance between the innermost turns of each layer exposed or in contact with the core insertion hole decreases at high humidity, and the coil characteristics fluctuate due to humidity. In addition, when the innermost peripheral turn exposed or in contact with the core insertion hole and the outer peripheral surface of the core are in contact with each other, a creeping leakage occurs through the outer peripheral surface of the core, or when a core having a low specific resistance is used, the innermost peripheral turn is reduced. It has been found that the ground insulation resistance of the Pb decreases and the coil characteristics deteriorate.
[0005]
The present invention has been made in view of the above problems, and has as its object to provide a printed coil type coil component fixed to a printed circuit board having excellent characteristics.
[0006]
[Means for Solving the Problems]
The printed coil type coil component fixed to the printed circuit board according to claim 1, wherein a soft magnetic core inserted into a through hole formed in the printed circuit board, and a spiral formed on the printed circuit board surrounding the through hole. In the printed coil type coil component provided with the printed coil, the innermost turn of the printed coil is formed apart from the through hole by a distance capable of securing electrical insulation between the core and the printed coil. It is characterized by:
[0007]
According to the present invention, the innermost turn of the print coil is formed at a predetermined distance (preferably 0.5 to 5 mm) from the through hole (core insertion hole).
[0008]
By doing so, the innermost turn of the printed coil can secure a sufficient electrical insulation distance with respect to the core or the through hole, and printing from the innermost turn through the inner circumferential surface of the core insertion hole can be performed. It is possible to satisfactorily prevent the interlayer leakage along the coil and the ground leakage through the outer peripheral surface of the core and the core itself, thereby preventing the deterioration of the electrical characteristics of the coil.
[0009]
If the distance between the innermost turn of the print coil and the through hole (core insertion hole) is less than 0.5 mm, the above problem occurs at high humidity. It is not preferable because it increases.
[0010]
In a preferred embodiment, a Mn-based ferrite core is employed as the core. This Mn-based ferrite core is obtained by mixing known trace elements into 70 to 85% of ferrous dioxide and 15 to 25% of manganese in a weight ratio.
[0011]
Although this Mn-based ferrite core has excellent soft magnetic properties, it has a problem of inferior electrical insulation. In this embodiment, however, the electrical contact between the printed coil and the Mn-based ferrite core is ensured by using the above-mentioned distance without using a bobbin. As a result, it is possible to improve the magnetic characteristics of the coil component without worrying about leakage.
[0012]
A printed coil type coil component fixed to a printed board according to claim 4, wherein the printed component includes a soft magnetic core fixed to the printed board, and a print coil formed on the printed board and forming a magnetic flux in the core. In a printed coil type coil component fixed to a substrate, the printed coil is a printed circuit board side half formed by each half turn of the printed coil formed on the printed circuit board in a direction parallel to each other and intersecting the magnetic flux direction of the core. Turn part,
A flexible substrate-side half-turn portion comprising each half-turn of the printed coil formed in a direction parallel to each other and intersecting with the magnetic flux direction of the core on a flexible substrate fixed to the printed substrate covering the core, The half turns of the printed circuit board-side half-turn portion are sequentially connected to the respective half turns of the flexible board-side half-turn portion to form the printed coil.
[0013]
In other words, in the present invention, each half turn in which each turn of the print coil interlinking with the magnetic flux direction of the core is formed on the printed circuit board, and each of the half-turns formed on the flexible board fixed to the surface of the printed circuit board covering this core. The half turns are sequentially connected to form a printed coil.
[0014]
Since the flexible board can be bent freely, the bend absorbs the thickness of the core mounted on the printed board (the width in the thickness direction of the printed board), and as a result, both ends of the half-turn formed on the flexible board Can be directly bonded to both ends of the half-turn formed on the printed circuit board by existing conductor bonding methods such as soldering, ultrasonic bonding, conductive adhesive, or easily bonded through solder balls or solder bumps Can be.
[0015]
In addition, the half turn of the flexible substrate and the half turn of the printed circuit board can be formed so as not to directly contact the core. In this case, electric leakage through the core itself or the surface of the core can be prevented well, and the coil characteristics can be improved. Degradation can be prevented.
[0016]
BEST MODE FOR CARRYING OUT THE INVENTION
Preferred embodiments of the printed coil type coil component fixed to the printed board of the present invention will be described with reference to the following examples.
[0017]
(Example 1)
An example of a choke coil as a printed coil type coil component fixed to a printed circuit board according to the first embodiment will be described with reference to FIGS. 1 is a plan view of a main part, and FIG. 2 is a longitudinal sectional view of a main part.
[0018]
1 is a printed circuit board, 2 is a core insertion hole (through hole), 3 is a core, and 4 is a printed coil.
[0019]
The printed circuit board 1 has a printed coil 41 made of a conductive pattern on the surface of the resin plate 10 and a printed coil 42 made of the conductive pattern on the back surface of the resin plate 10. The coil may be multilayered. Various circuit components including a capacitor constituting an LC smoothing circuit (low-pass filter) are mounted on the printed circuit board 1 to realize an initial circuit such as a DC-DC converter.
[0020]
Therefore, the printed coil 4 of this embodiment is composed of two printed coils 41 and 42 which overlap in the thickness direction of the printed circuit board 1 and are connected in series with each other.
[0021]
The print coils 41 and 42 are spirally formed around the core insertion hole 2, and the straight rod-shaped Mn-based ferrite core 3 fixed to the bottom surface of a case (not shown) is inserted through the core insertion hole 2. I have.
[0022]
A through-hole 11 is formed in the resin plate 10 of the printed board 1, and a via-hole conductor 12 is buried in the through-hole by a known printing method. The via-hole conductor 12 connects the innermost ends A, A of the two print coils 41, 42, whereby the two print coils 41, 42 are connected in series, and the number of turns of the print coil 4 Are the sum of the print coils 41 and 42. Reference numeral 43 denotes the outermost peripheral end of the print coil 41, and reference numeral 44 denotes the outermost peripheral end of the print coil 42, which constitute both ends of the print coil 4.
[0023]
What is important in this embodiment is that the distance d between the innermost turns of each of the printed coils 41 and 42 and the core insertion hole 2 is 2 mm (preferably 0.5 to 5 mm). .
[0024]
In this manner, sufficient electrical insulation between the printed coils 41 and 42 and the Mn-based ferrite core 3 having electrical conductivity can be sufficiently ensured. Therefore, a Mn-based ferrite core having excellent soft magnetic properties is employed. A choke coil having excellent magnetic properties can be formed.
[0025]
The outermost peripheral end 44 of the printed coil 42 is projected to the surface side of the printed circuit board 1 by a not-shown via-hole conductor at a position not shown, and then connected to other circuit components such as the outermost peripheral ends 43 and 44 smoothing circuits. Is done. Note that the print coil 42 may be formed inside the printed circuit board 1 instead of the rear surface.
[0026]
(Example 2)
A choke coil according to another embodiment will be described below with reference to FIGS. FIG. 3 is a plan view of a main part of the printed circuit board as viewed from the front, and FIG. 4 is a plan view of a main part of the printed circuit board as viewed from the back.
[0027]
Reference numeral 1 denotes a printed circuit board in which two core insertion holes (through holes) 21 and 22 are formed at a predetermined distance, and both legs of a U-shaped core (not shown) are inserted into these core insertion holes 21 and 22. The ends of both legs contact the opposite ends of an I-shaped core (not shown), thereby forming a closed magnetic circuit.
[0028]
A printed coil 41 made of a conductive pattern is formed on the surface of the resin plate 10 of the printed board 1, and a printed coil 42 made of the conductive pattern is formed on the back surface of the resin plate 10.
[0029]
Through holes 111 and 112 are formed in the printed circuit board 1, and the through holes 111 and 112 are filled with through hole conductors for connecting the print coils 41 and 42.
[0030]
As shown in FIG. 3, the front side print coil 41 has a spiral coil formed around the core insertion hole 21 in a clockwise direction from the through hole 111 as a starting point. 22 is connected to the outermost peripheral end of a spiral coil formed in a clockwise direction with the through hole 112 as a starting point.
[0031]
As shown in FIG. 4, the printed coil 42 on the back side has a spiral coil formed counterclockwise around the core insertion hole 21 starting from the through hole 111, and a spiral coil formed around the core insertion hole 22 starting from the through hole 112. And a spiral coil formed in a counterclockwise direction. Further, among the printed coils 42, the innermost peripheral end of the spiral coil that goes around the core insertion hole 21 is connected to one end of the front side printed coil 41 through the through hole 111, and the innermost peripheral end of the spiral coil that goes around the core insertion hole 22. Is connected to the other end of the print coil 41 on the front side through a through hole 112.
[0032]
In this way, the outermost ends of the back side print coils 41 and 42 are both ends of the print coil composed of the two print coils 41 and 42 connected in series with each other. In addition, the number of turns can be increased while reducing the space required for the print coil and simplifying the wiring structure.
[0033]
(Example 3)
An example of a choke coil as a print coil type coil component fixed to a printed circuit board according to the third embodiment will be described with reference to FIGS. FIG. 5 is a vertical sectional view of a main part, and FIG. 6 is a plan view of a main part.
[0034]
5 is a printed board, 6 is a core, and 7 is a flexible board.
[0035]
The printed board 5 has a conductor pattern described later on the surface 50 of the resin plate, and the flexible board 7 also has a conductor pattern on the surface 70 on the printed board 5 side. A ring-shaped core 6 is fixed to the surface 50 of the printed board 5, and a flexible board 7 is fixed to the printed board 1 so as to cover the core 6.
[0036]
As shown in FIG. 6, on the surface 50 of the printed board 5, a printed board side half-turn portion 8 formed by half of each turn of the printed coil, that is, a half turn 80, is formed. On the front surface, a flexible substrate side half-turn portion 9 constituted by the other half of each turn of the print coil, that is, a half turn 90 is formed. In FIG. 5, these half-turn portions 8, 9 are not shown.
[0037]
Each half turn 80 constituting the printed board side half turn portion 8 is formed by a straight conductor pattern which is formed in parallel with each other and is inclined downward and to the left as shown by a broken line in FIG. As shown by the broken lines in FIG. 6, each half turn 90 constituting the flexible substrate side half turn portion 9 is formed by a straight conductor pattern which is formed diagonally to the right and inclined downward to the right.
[0038]
The core 6 is formed of a nickel-based ferrite core having excellent electrical insulation, and is inserted between the two half-turn portions 8 and 9. The right end of the half turn 80 and the right end of the half turn 90 are soldered, and the left end of the half turn 80 and the left end of the half turn 90 are also soldered to form one coil, that is, a printed coil as a whole.
[0039]
The flexible board 7 may be adhered to the surface 50 of the printed board 5. Although the core 6 is fixed to the printed circuit board 5 by this bonding or the joining of the half turns 80 and 90, the core 6 may be bonded to the printed circuit board 5.
[0040]
In this way, even if the number of turns increases, the coil diameter does not increase, and a small and easy-to-manufacture printed coil can be realized.
[0041]
(Modification)
In the above embodiment, a half-turn is formed on the core-side surface of the flexible board 7 and the printed board 5, but a half-turn is formed on the surface opposite to or inside the core-side surface of the flexible board 7 and the printed board 5. Is also good. Further, a half-turn may be formed on the surface of the flexible substrate 7 and the printed circuit board 5 on the core side, and a resin insulating film may be interposed between the half-turn and the core.
[0042]
Since the flexible substrate 6 can be freely bent, the bending absorbs the thickness of the core 6 mounted on the printed circuit board 5 (width in the thickness direction of the printed circuit board) to easily form a multi-turn printed coil. can do.
[0043]
(Modification)
In the above embodiment, a choke coil, that is, an inductor, particularly a choke coil for a smoothing circuit has been described. However, the present invention can be applied to an inductor for other uses and further to a transformer.
[Brief description of the drawings]
FIG. 1 is a plan view of a main part of a printed coil according to a first embodiment.
FIG. 2 is a longitudinal sectional view of a main part of the print coil of FIG. 1;
FIG. 3 is a main part plan view of a printed circuit board of a printed coil of Example 2 as viewed from the surface.
FIG. 4 is a plan view of a main part of a printed circuit board of a printed coil of Example 2 as viewed from the back.
FIG. 5 is a vertical sectional view of a main part of a printed coil according to a third embodiment.
FIG. 6 is a plan view of a main part of the print coil of FIG. 5;
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 Printed circuit board 2 Core insertion hole 3 Core 4 Print coil

Claims (4)

A soft coil core inserted into a through hole formed in a printed board, and a printed coil type coil component including a printed coil spirally formed in the printed board surrounding the through hole,
A print coil type fixed to a printed circuit board, wherein an innermost turn of the print coil is formed apart from the through hole by a distance capable of securing electrical insulation between the core and the print coil. Coil parts. The printed coil type coil component fixed to the printed circuit board according to claim 1,
A printed coil type coil component fixed to a printed circuit board, wherein the core comprises a Mn-based ferrite core. The printed coil type coil component fixed to the printed circuit board according to claim 1,
A printed coil type coil part fixed to a printed circuit board, wherein the distance is set to 0.5 to 5 mm. A soft coil core fixed to a printed board, and a printed coil type coil component fixed to a printed board including a printed coil formed on the printed board and forming a magnetic flux in the core,
The print coil is
A printed circuit board-side half-turn portion consisting of each half-turn of the printed coil formed on the printed circuit board in a direction parallel to each other and crossing the magnetic flux direction of the core;
A flexible substrate side half-turn portion comprising each half turn of the printed coil formed in a direction parallel to each other and intersecting with the magnetic flux direction of the core on a flexible substrate fixed to the printed substrate covering the core,
Consisting of
The respective half turns of the printed circuit board side half turn portion are sequentially connected to the respective half turns of the flexible substrate side half turn portion to form the printed coil, and are fixed to the printed circuit board. Printed coil type coil parts.

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