JPH08264321A - Chip transformer - Google Patents

Abstract

PURPOSE: To lessen a winding coil in electrical field strength so as to improve a chip transformer in migration and the like by a method wherein winding coils are successively arranged on the plane in a concentric manner from inside in the order of number of wire turns. CONSTITUTION: Three coil patterns P1 , P2 , and P3 different from each other in conductor width after sintering are printed on magnetic sheets 1 to 21 of high insulation resistance. The sheets 1 to 21 are successively stacked up, and the open ends of the vertically adjacent conductor patterns P1 , P2 , and P3 are connected together through through-holes to form three concentric winding coils N1 , N2 , and N3 . The numbers of wire turns of the winding coils N1 , N2 , and N3 are set to 11.3T or so, 6.8T or so, and 15.8T or so. When a chip transformer is manufactured, the winding coils N1 , N2 , and N3 are successively arranged in a concentric manner on the plane in the order of number of turns or the coils N3 , N1 , and N2 are arranged in this sequence from inside.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a laminated / multi-coil type chip transformer used in various electronic devices.

[0002]

2. Description of the Related Art Conventionally, an integrated structure type chip transformer of this type, which is characterized by its small size and thin shape, has a plurality of types of conductor patterns P1 as shown in FIG.
, P2, P3 printed magnetic sheets 1-17 and unpatterned non-patterned magnetic sheet F are connected through holes at both open ends of the conductor patterns P1, P2, P3 formed in the upper and lower layers. , Laminating, crimping and sintering to form a plurality of winding coils N1, N2 and N3 in concentric circles,
The lead-out coils N1, N2 and N3 are respectively connected to output terminals formed on the outer circumference of the chip transformer. In order to make the magnetic flux density uniform, the orbiting coils N1, N2, and N3 are arranged from the inner side of the concentric surface in the order of a small number of coil turns, for example, N2, N1, and N3, as shown in FIG.

[0003]

However, when the winding coils N1, N2, and N3 are arranged as in the above-described conventional example, as is apparent from the partially enlarged cross-sectional view of the winding coil shown in FIG. 7, the inside of the concentric plane is shown. Since the extraction electrode D1 of this coil intersects the outer winding coil N3 with only one magnetic sheet and intersects in the upper and lower layers, it is difficult to secure the distance between the extraction electrode and another coil pattern. The electric field strength becomes large. In general, magnetic material sheets are prone to defects such as pinholes. Should such defects occur at the intersections, the extraction electrode and the coil patterns in the upper and lower layers will be short-circuited, generating heat, smoking, or in use. However, inconvenience such as inducing migration is likely to occur, resulting in lack of reliability.

As a solution to such inconvenience, the extraction electrode D
Sandwich the upper and lower sides of 1, D2, D3 with green sheets for insulation and reinforcement, or take-out electrodes D1, D2, D3
It is conceivable to temporarily stretch the sheet in the upward or downward direction (laminating direction) and then pull it out in the outer circumferential direction to avoid crossing with the coil patterns in the upper and lower layers. However, it is necessary to reconnect the upper and lower connections of the coil pattern interrupted by the intervening insulating sheet with new through holes, which lowers the electrical reliability and significantly increases the number of steps. (For through-hole connection, a dedicated sheet with through-holes formed and filled with a conductor is required.) In the case of, the extraction pattern becomes complicated to extract the extraction electrodes D1, D2, D3 in the stacking direction. Moreover, since it is necessary to connect each of them with through holes, this also poses a problem with respect to electrical reliability, man-hours, and thinning.

An object of the present invention is to provide a highly reliable chip transformer in which the electric field strength of the orbiting coil is reduced by securing a sufficient distance between the input and output coils, and migration and the like are improved.

[0006]

That is, according to the present invention, a plurality of magnetic sheets (1 to N) on which a plurality of types of coil patterns (P1 to Pn) are printed and a magnetic field through which magnetic flux passes above and below the coil portion. A laminated / multi-coil type chip transformer in which a plurality of types of orbiting coils (N1 to Nn) are concentrically formed by laminating, press-bonding and sintering non-patterned magnetic sheets (F) so that the path circulates, The winding coil (N
1 to Nn) are arranged from the inside in the concentric plane in order from the one having the largest number of coil turns.

Further, in the present invention, it is preferable to use a high magnetic flux density material for the unpatterned magnetic sheet (F).

[0008]

[Operation] According to the present invention having the above-described structure, when a plurality of magnetic coils having a coil pattern printed thereon are laminated, pressure-bonded and sintered to form a plurality of concentric coils in a concentric shape, the number of coil turns is If they are arranged from the inner side of the concentric plane in order from the largest number, the distance between the extraction electrode and the outer coil can be increased by at least the difference in the number of turns, and the electric field strength of the orbiting coil can be reduced.

Further, since there are a plurality of magnetic sheets interposed between the extraction electrode and the coil, even if a defect such as a pinhole occurs in the magnetic sheet, the probability of these defects overlapping is extremely low, and a short circuit or migration occurs. Etc., the risk is greatly reduced.

Further, in the above-described structure, since the winding coil having a larger number of turns is arranged on the inner side where the coil diameter is smaller, the winding length of the coil having the maximum resistance can be shortened and the coil resistance can be reduced.

Further, in the present invention, when a high magnetic flux density material is used for the unpatterned magnetic sheet, leakage of magnetic flux can be prevented.

[0012]

DESCRIPTION OF THE PREFERRED EMBODIMENTS FIG. 1 is a diagram showing a coil pattern in the case of applying the present invention to produce a laminated / multi-coil type chip transformer used in a DC-DC converter.

In this embodiment, the width of the conductors after sintering is 60, respectively.
Three types of coil patterns P1, P2, P3 having a thickness of 0 μm, 150 μm, and 150 μm, a green sheet having a high insulation resistance and a thickness of 70 μm (hereinafter referred to as a magnetic sheet) 1
21 to 21 are printed, and these are sequentially laminated, and the respective conductor patterns P1, P2, P3 formed in the adjacent upper and lower layers.
The three open coils N1, N2, and N3 are concentrically formed by connecting the open ends of the open coil to each other through through holes. The number of coil turns is 11.3 T (turns) for the rotary coil N1, and 6 for the rotary coil N2. .8T, orbiting coil N3 is 1
It is 5.8T.

A feature of the present invention is that, when a chip transformer is manufactured, the orbiting coils having a larger number of coil turns are sequentially arranged inside the concentric plane in the order from the inside. Orbiting coil N3, Orbiting coil N1
, The orbiting coil N2 is arranged.

That is, as shown in FIG. 1, in the coil pattern P3 of the orbiting coil N3 disposed on the innermost side of the concentric surface, the magnetic sheet 21 is separated by 21 layers at the starting end (coil winding start) N3S. Is the terminal N3E (end of coil winding), and the coil pattern of the orbiting coil N1 arranged on the inner side.
The magnetic sheet 18 is separated by 15 layers at the starting end N1S and the magnetic sheet 18 becomes the ending end N1E. Further, in the coil pattern P2 of the winding coil N2 arranged on the outermost side, the magnetic sheet 7 is the starting end N2S and the magnetic sheet 15 separated by nine layers is the ending end N2E. Further, coil lead-out electrodes D1, D2, D3 are printed at the beginning and end of each of the winding coils N1, N2, N3, and are connected to coil terminals provided on the outer periphery of the chip transformer (not shown). The magnetic sheets 1-2
1 and unpatterned magnetic sheet F with no conductor printed
The state of stacking is similar to that of the conventional coil pattern diagram shown in FIG.

The magnetic sheets 1 to 21 laminated in such a pattern arrangement are unpatterned magnetic sheets F on which no conductor is printed (not shown, so that a necessary magnetic path cross-sectional area can be obtained above and below the laminated magnetic sheets. (A plurality of sheets are stacked on top of each other), and they are pressure-bonded by a hot press and further sintered to produce a laminated / multi-coil type chip transformer. Its appearance is shown in FIG. 2 and its internal structure is shown in FIG.

FIG. 4 shows an enlarged partial sectional view of the spiral coil. As is clear from the drawing, coil patterns P1 and P are shown.
2. If P3 is arranged from the inside of the concentric plane in order from the winding coil having the larger number of coil turns, the distance between the coil extraction electrode and the outer coil can be increased by at least the number of turns difference, and the electric field strength of the winding coil is reduced by that amount. It will be. For example, in the case of this embodiment, the extraction electrode D1 of the winding coil N1
And three magnetic sheets are interposed between the outer peripheral coil N2 and the outer peripheral coil N2.

Here, the applied voltage (V) of the winding coil is set to 2
The electric field strength (Eold) of the spiral coil of the conventional structure and the electric field strength (Enew) of the spiral coil of the present invention are calculated and compared at 5 V and the thickness (t) of the magnetic sheet after sintering is 60 μm.

That is, from Eold = V / t, Eold is 417
V / mm, on the other hand, Enew = V / 3t, so Enew is 139.
It is V / mm, and it can be seen that the structure of the present invention greatly reduces the electric field strength of the winding coil.

Further, since the winding coil having a larger number of turns is arranged inside the smaller coil diameter, the winding length of the coil having the maximum resistance can be shortened and the coil resistance can be reduced. Orbiting coil N3 (1 with maximum resistance
5.8T), the conventional structure and the new structure were compared, and the coil direct current resistance was 2.3Ω in the conventional structure and 1.8Ω in the new structure of the present invention, which was about 20% lower.

When a high magnetic flux density material is used as the magnetic sheet F on which no pattern is printed, leakage of magnetic flux from the formed magnetic path can be prevented.

The number of windings is 11.3T, 6.8T, 1
The chip transformer composed of three types of 5.8T winding coils N1, N2 and N3 has been described, but the number of winding coils and the number of windings are not limited to this.

[0023]

As described above, according to the present invention, a plurality of magnetic sheets on which a plurality of types of coil patterns are printed, and a non-patterned magnetic sheet so that magnetic paths through which magnetic flux passes above and below the coil portions circulate. In a laminated / multi-coil type chip transformer, which is formed by stacking, crimping, and sintering sheets to form a plurality of types of winding coils in a concentric shape, the winding coils are arranged in the concentric plane in descending order of the number of coil turns. Since it is arranged from above, the distance between the extraction electrode and the coil outside thereof can be increased by at least the difference in the number of turns, and the electric field strength of the orbiting coil can be significantly reduced.

Further, since there are a plurality of magnetic sheets interposed between the extraction electrode and the coil, even if there is a defect such as a pinhole in the magnetic sheet, the probability of these defects overlapping is extremely low, and a short circuit or a short circuit occurs. The risk of migration etc. is greatly reduced and the reliability is improved.

Further, in the above structure, the coil having a larger number of turns is arranged on the inner side of which the coil diameter is smaller, so that the coil circumference having the maximum resistance can be shortened and the coil resistance can be reduced. Therefore, the heat loss is improved and the efficiency of the chip transformer is improved.

Further, according to the present invention, since the high magnetic flux density material is used for the unpatterned magnetic material sheet, magnetic flux leakage is eliminated and reliability is improved.

[Brief description of drawings]

FIG. 1 is a diagram showing a coil pattern of a laminated / multi-coil type chip transformer according to the present invention.

FIG. 2 is an external perspective view of the same multilayer / multi-coil type chip transformer.

FIG. 3 is a cross-sectional view showing the structure of a laminated / multi-coil type chip transformer.

FIG. 4 is an enlarged partial sectional view of a spiral coil of a laminated / multi-coil type chip transformer.

FIG. 5 is a diagram showing a coil pattern of a conventional laminated / multi-coil type chip transformer.

FIG. 6 is a sectional view showing the structure of a laminated / multi-coil type chip transformer.

FIG. 7 is an enlarged partial sectional view of a spiral coil of a laminated / multi-coil type chip transformer.

[Explanation of symbols]

 1 to N magnetic sheet D1 to Dn coil extraction electrode F unpatterned magnetic sheet P1 to Pn coil pattern N1 to Nn winding coil

Claims (2)

[Claims] 1. A plurality of types of coil patterns (P1 to P)
n) printed magnetic sheets (1 to N) and a plurality of pattern-free magnetic sheets (F) stacked, crimped, and sintered so that the magnetic paths through which magnetic flux passes above and below the coil portion circulate. In a laminated / multi-coil type chip transformer formed by concentrically forming various types of winding coils (N1 to Nn), the winding coils (N1 to Nn) are arranged inside the concentric plane in the order of increasing number of coil turns. A chip transformer characterized by being placed from. 2. The chip transformer according to claim 1, wherein a high magnetic flux density material is used for the unpatterned magnetic sheet (F).