JPH08130116A - Chip transformer - Google Patents

Abstract

PURPOSE: To provide a very reliable chip transformer which has no shorts nor migration. CONSTITUTION: A chip transformer is made by a method wherein a plurality of magnetic green sheets 11-13 on which a plurality of coil patterns P which become input and output coils or a coil extraction pattern are printed are laminated and bonded and magnetic sheets which do not have a coil pattern printed which allows a magnetic path through which a magnetic flux passes to go around are laminated and bonded on and under the coil sections and then the laminate is sintered. In such a chip transformer, an insulators Z1, etc., are located between the coil extraction pattern E and the coil patterns P. The insulators are made by screen printing two or more insulating magnetic sheets or insulating magnetic paste. The insulator is let to exist only at the extraction pattern E section. The insulators Z1, etc., are made of non-magnetic insulating ceramic.

Description

Detailed Description of the Invention

[0001]

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

[0002]

2. Description of the Related Art Conventionally, an integrated structure type chip transformer of this type characterized by being small and thin has an input / output coil as shown in FIG. 5 on an insulating magnetic sheet 18 produced by a doctor blade method or the like. It is manufactured by printing a plurality of conductive patterns P, stacking a plurality of them, press-bonding them, and sintering by a hot press.

As shown in FIG. 6, the structure is such that upper and lower layer patterns P are sequentially through-hole connected (indicated by a dotted line) to form a desired winding coil, and the coil pattern is wound around the input / output terminals of these winding coils. The magnetic sheet is not pulled out to the side surface of the transformer by the pullout pattern E.

[0004]

However, although the above-mentioned drawing pattern E intersects with the upper layer pattern and the lower layer pattern through one sheet of the insulating magnetic material sheet, it is produced by the doctor blade method or the like. Magnetic material sheets are prone to defects such as pinholes, and if these defects occur on the magnetic material sheets at the intersections, the drawing pattern and the coil patterns in the upper and lower layers are short-circuited, causing the chip transformer to generate heat, emit smoke, or are in use. There is a risk of causing migration and becoming defective.

An object of the present invention is to solve the above problems and provide a highly reliable chip transformer which prevents short circuits and migration.

[0006]

That is, in the present invention, a plurality of magnetic material green sheets (1 to n) printed with a plurality of conductor patterns (P) and lead-out patterns (E) to be input / output coils are laminated. In a chip transformer formed by sintering after pressure bonding, insulators (Z1, Z2) are provided between the coil pattern (E) and the coil pattern (P).
It was constituted by interposing. Further, in the present invention, the above-mentioned insulator is two or more insulating magnetic material sheets (Z1). Further, in the present invention, the insulator is formed by screen printing using the insulating magnetic material paste (Z2). Further, in the present invention, the insulator is arranged only in the lead-out pattern (E) portion. In the present invention, the insulators (Z1, Z2) are formed by screen printing of a non-magnetic insulating ceramic sheet or a non-magnetic insulating ceramic paste.

[0007]

[Operation] With the above structure, in the present invention, even if the magnetic material sheet has a defect such as a pinhole, the magnetic material sheet is protected by the newly interposed insulator, so that the insulation between the patterns is maintained.

Further, in the present invention, when a non-magnetic insulating ceramic sheet is used as the insulator, a gap is created between the coils to increase the magnetic resistance, and the magnetic saturation of the chip transformer is relaxed.

[0009]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to FIGS.

FIG. 1 shows an example in which an insulative magnetic material sheet Z1 is used as an insulator newly interposed between a lead-out pattern E serving as an input / output terminal of a coil and a coil pattern P.
This figure is a cross section of the portion corresponding to the 11th, 12th, and 13th layers (the laminated portion where the drawing pattern E and the coil pattern P intersect) of the laminated arrangement of the magnetic material green sheets for forming the spiral coil shown in FIG. The figure is shown. The eleventh layer is a magnetic material green sheet 11 having a coil pattern P printed on its surface. The 12th layer is the magnetic material green sheet 1
An insulating magnetic material sheet Z1 is laminated as an insulator on the back side of 2 to form a two-layer insulating structure, and a lead-out pattern E for input / output terminals of the spiral coil is printed on the front side.
The 13th layer has the same 2 layer structure as the above 12th layer sheet,
The coil pattern P is printed on the front side.

The drawing pattern E formed on the 12th layer sheet and the upper and lower layers (1
The coil patterns P formed in the first layer and the thirteenth layer are insulated by the two insulating magnetic material sheets. The external structure of this 12th-layer magnetic sheet is shown in FIG. still,
The end portion of each pattern P is drawn to the back surface by a through hole and connected to the pattern P of another layer as shown by the dotted line in FIG.

On the other hand, FIG. 2 shows an example in which an insulator is formed by screen printing using an insulating magnetic material paste Z2. This figure also shows a sectional view of the 11th, 12th, and 13th layers of the sheet in FIG. 6, and in this embodiment, the 11th layer is the magnetic material green sheet 11, and the coil pattern P is printed on the surface.
The 12th and 13th layers are obtained by screen-printing an insulating magnetic material on a magnetic material green sheet in a paste form, and forming a pattern P on the green sheet. The coil pattern P is protected by two layers of one magnetic material green sheet 12 or 13 and another insulating magnetic material paste Z2. In this case, since the insulating magnetic material paste Z2 is formed by screen printing, it is possible to make it thinner than the above-mentioned magnetic material sheet.

FIG. 3 shows an example in which an insulator is interposed only in the extraction pattern E portion. In this case, the eleventh layer and the thirteenth layer are magnetic material green sheets, and only the twelfth layer in which the extraction pattern E is formed is subjected to the insulation treatment. That is, the insulating magnetic material paste is screen-printed on the terminal portions of the magnetic material green sheet 12, the extraction pattern E is printed, and the insulating magnetic material paste is further printed on the extraction pattern E to form a sandwich. is there. In this case, since only the extraction pattern E portion of the magnetic sheet on which the extraction pattern E is formed is insulated,
The manufacturing process is simplified.

In this way, when the chip transformer is manufactured, the insulating magnetic material sheet Z1 is formed on the upper and lower layers of the extraction pattern E.
Since the formed conductor portion is always protected by the two-layer insulator by interposing the insulator such as the insulating magnetic material paste Z2, the insulating property between the patterns can be kept extremely good.

When a nonmagnetic insulating ceramic material is used instead of the insulating magnetic material as the insulator Z described above, the magnetic resistance between the coils is increased due to the gap generated by the ceramic material, and the transformer itself. Therefore, in addition to the above-described insulating effect, it also has an excellent effect of magnetically enduring high power.

[0016]

As described above, according to the present invention, an integral structure formed by laminating, crimping and sintering a plurality of insulating magnetic material sheets printed with a plurality of conductor patterns to be input / output coils. In this chip transformer, an insulator is interposed between the coil drawing pattern and the coil pattern, so even if a defect such as a pinhole occurs in the magnetic material green sheet, the conductor is protected by the interposed insulator. Therefore, short circuit or migration between the input / output coils or between the outputs is prevented, and the reliability of the chip transformer is significantly improved.

Further, according to the present invention, when the insulator is screen-printed with a non-magnetic insulating ceramic sheet or a non-magnetic insulating ceramic paste, a gap is generated between the coils due to the insulating ceramic material, so that a magnetic field is generated. The resistance becomes higher, the magnetic saturation of the chip transformer is relaxed, and it becomes possible to endure higher power magnetically.

[Brief description of drawings]

FIG. 1 is a cross-sectional view of an insulating magnetic material sheet that constitutes a chip transformer according to the present invention. ●

FIG. 2 is a sectional view of an insulating magnetic material sheet different from that of FIG. 1, which constitutes the chip transformer.

FIG. 3 is a sectional view of an insulating magnetic material sheet different from that of FIG. 2, which constitutes the chip transformer.

FIG. 4 is a perspective view showing an external structure of an insulating magnetic material sheet that constitutes the chip transformer.

FIG. 5 is a diagram showing a conductor pattern for forming a spiral coil.

FIG. 6 is a diagram showing a stacking arrangement of magnetic material green sheets forming a chip transformer. ●

[Explanation of symbols]

1 to n Magnetic material green sheet E Coil extraction pattern P Coil pattern S1, S2 Magnetic sheet without coil pattern printed Z1 Insulator (insulating magnetic material sheet) Z2 Insulator (insulating magnetic material paste)

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Masahiro Iguchi 5-36-1 Shimbashi, Minato-ku, Tokyo Fuji Electric Chemical Co., Ltd. (72) Fumiaki Nakao 5-36-11 Shinbashi, Minato-ku, Tokyo Fuji Electrochemical Co., Ltd.

Claims (5)

[Claims] 1. A plurality of magnetic material green sheets (1 to n) on which a plurality of coil patterns (P) to be input / output coils and coil drawing patterns (E) are printed, and above and below the coil portions, A magnetic sheet on which a coil pattern is not printed so that the magnetic path through which the magnetic flux passes goes around (S1
, S2) are laminated and pressure-bonded and then sintered, and insulation is provided between the coil drawing pattern (E) on the inner side of the coil and the coil pattern (P) on the outer side of the coil. A chip transformer characterized in that bodies (Z1, Z2) are interposed in the stacking direction. 2. The chip transformer according to claim 1, wherein the insulator is two or more insulating magnetic material sheets (Z1). 3. The insulating material is an insulating magnetic material paste (Z
2. The chip transformer according to claim 1, which is formed by screen printing according to 2). 4. The insulator according to claim 1, wherein the insulator is interposed only in the extraction pattern (E) portion.
Alternatively, the chip transformer according to claim 3. 5. The chip transformer according to claim 1, wherein the insulators (Z1, Z2) are formed by screen-printing a non-magnetic insulating ceramic sheet or a non-magnetic insulating ceramic paste.