JP2000340445A - Green tape, manufacture thereof, multilayer ceramic substrate, planar transformer, switching power supply - Google Patents

Abstract

PROBLEM TO BE SOLVED: To reduce the variation in the width of a conductor by pressing a projecting part of a molded object against the surface of a green tape to form a recess in a conductor printing part on the surface and then printing the recess with conductor ink. SOLUTION: A projecting type molded object 11 is formed with a projecting part 11A, which is projecting by approximately D2=70 μm from the surface 11B of the projecting type molded object 11. The projecting part 11A is pressed against a soft green type 1 in the direction shown by an arrow A1 to form a recess 1A in the green tape 1. The recess 1A is printed with conductor ink 12 so that the conductor ink 12 may be below the surface 1B of the green tape 1 by approximately D3=5 μm-15 μm. By this method, there is no leakage of the conductor ink 12 out of the recess 1A and therefore the bleeding of the conductor ink 12 can be prevented. Moreover, the variation in the width of the conductor ink 12 can be reduced.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for manufacturing a green tape, a multilayer ceramic substrate, a planar transformer, a switching power supply, and a green tape used for portable equipment such as a printer and a notebook personal computer, and more particularly to a thin tape on which a conductor is printed. The present invention relates to a method for manufacturing a green tape, a multilayer ceramic substrate, a planar transformer, a switching power supply, and a green tape.

[0002]

2. Description of the Related Art With reference to FIGS. 12 and 13, a general method of printing a conductor of a green tape in a planar transformer in which a conductor of a switching power supply transformer coil is printed on a green tape will be described.

Referring to FIG. 12, a via is opened in a green tape (multi-layer ceramic tape) 100, the via is printed, and a conductor 101 is printed. Green tape 100
Has a thickness D2 of 100 μm to 200 μm. The printed conductor 101 has a thickness D1 of about 10 μm to 20 μm.
Having.

[0004] Referring to FIG.
Are laminated by thermocompression bonding, the conductor printing of the outer layer is performed, and the firing is performed, whereby the multilayer ceramic substrate 110 having a transformer is manufactured.

[0005] There is also a method in which the green tape 100 is laminated and then baked, and the conductor printing of the outer layer is performed, and then the outer layer is baked.

[0006]

In a switching power supply transformer, if the resistance of the coil portion is large, heat loss is generated by multiplying the square of the value of the current flowing through the coil portion by the resistance value, so that the efficiency of the switching power supply is reduced. I do.

[0007] The conductor 10 printed to reduce the resistance value of the conductor coil in order to prevent the efficiency of the switching power supply from decreasing.
1 is increased, the multilayer ceramic substrate 110 shown in FIG.
After lamination, the portion 100A corresponding to the conductor 101 on the surface of the green tape 100 after lamination becomes thicker than the portion 100B corresponding to the portion without the conductor 101. Therefore, the raised portion 100A corresponding to the conductor 101 is raised.

The raised portion 100 corresponding to the conductor 101
The swelling of A causes blurring when printing on the surface of the multilayer ceramic substrate 110, and causes cracking of the multilayer ceramic substrate 110 during firing.

When printing is performed in a state where the multilayer ceramic substrate 110 has cracks, problems such as bleeding 101A occur. In the case of printing after firing, defects such as bleeding similarly occur. If a defect such as bleeding occurs, the width of the conductor 101 varies widely, and short-circuits with an adjacent pattern. In order to prevent a short circuit with an adjacent pattern, the overall thickness of the multilayer ceramic substrate 110 after lamination is made uniform, or the conductor 1 is not printed when the conductor 101 is printed.
It is necessary to prevent bleeding 101A from occurring at 01.

From the above circumstances, the thickness D1 of the conductor 101
Can usually only be about 10 μm to 20 μm.

Since the resistance value of the primary side transformer coil is about 6 ohms, heat loss due to current increases. As a result, a rise in the temperature of the transformer coil becomes a problem.

There is also a problem that the efficiency of a switching power supply using the above-described transformer coil tends to be about 3 to 7% lower than the efficiency of a power supply equipped with a normal winding type transformer.

An object of the present invention is to provide a method of manufacturing a green tape, a multilayer ceramic substrate, a planar transformer, a switching power supply, and a green tape in which the width of a conductor is small.

Another object of the present invention is to provide a method of manufacturing a green tape, a multilayer ceramic substrate, a planar transformer, a switching power supply, and a green tape in which a conductor does not bleed during printing of the conductor.

Still another object of the present invention is to provide a green tape, a multilayer ceramic substrate, a planar transformer, a switching power supply, which does not cause blurring when printing on the surface of the multilayer ceramic substrate and does not cause cracking in the multilayer ceramic substrate during firing. And a method of manufacturing a green tape.

Still another object of the present invention is to provide a method of manufacturing a green tape having a thick conductor, a multilayer ceramic substrate, a planar transformer, a switching power supply, and a green tape.

Still another object of the present invention is to provide a method of manufacturing a green tape, a multilayer ceramic substrate, a planar transformer, a switching power supply, and a green tape having a low resistance value of a coil portion.

Still another object of the present invention is to provide a method of manufacturing a green tape, a multilayer ceramic substrate, a planar transformer, a switching power supply, and a green tape, which cause less heat loss due to electric current.

[0019]

A method for manufacturing a green tape according to the present invention is a method for manufacturing a green tape on which a conductive ink is printed, wherein a groove is formed in a conductive printing portion on the surface of the green tape. One step and a second step of printing a conductive ink in the groove,
The step includes a third step of pressing the convex portion of the convex molded product against the surface of the green tape, thereby achieving the above object.

[0020] The third step may include a step of pressing the convex portion against the surface of the green tape such that the depth of the groove is substantially 70 μm.

[0021] The second step may include a step of printing the conductive ink such that the surface of the conductive ink is lower than the surface of the green tape.

The green tape according to the present invention is a green tape on which conductive ink is printed, wherein the green tape has a groove formed in a conductive printed portion on the surface of the green tape and a green tape printed on the groove. And a conductor ink, wherein the conductor ink is printed such that the surface of the conductor ink is lower than the surface of the green tape, thereby achieving the above object.

The conductive ink has a thickness of 5 μm from the surface.
It may be printed so as to be about 15 μm lower.

The multilayer ceramic substrate according to the present invention is a multilayer ceramic substrate on which a green tape on which a conductive ink is printed is laminated, wherein the green tape has a groove formed in a conductive printed portion on the surface of the green tape. And a conductive ink printed in the groove, wherein the depth of the groove is substantially 70 μm, whereby the object is achieved.

The conductor ink may be printed so that the thickness of the conductor ink is about 55 μm to 65 μm.

The coil substrate with a built-in ceramic according to the present invention is a coil substrate with a built-in ceramic on which a green tape on which a conductive ink is printed is laminated, wherein the green tape is formed on a conductive printed portion on the surface of the green tape. It has a groove, conductive ink printed on the groove, and a coil formed on the surface of the green tape, thereby achieving the above object.

[0027] The coil includes a primary coil, a secondary coil, and a control coil.
The secondary coil and the control coil may include a five-turn coil stacked on a zero layer, and each of the secondary coil and the control coil may include a 3.5-turn coil stacked on a two layer.

[0028] The green tape may be composed of a glass-based low-temperature firing type substrate.

A planar transformer according to the present invention is a planar transformer having a coil substrate with a built-in ceramic and a ferrite core. The coil substrate with a built-in ceramic is formed by laminating a green tape on which conductive ink is printed. The green tape has a groove formed in a conductor printing portion on the surface of the green tape, a conductor ink printed on the groove, and a coil formed on the surface of the green tape, whereby The above object is achieved.

A switching power supply according to the present invention includes a planar transformer according to claim 11 and a control circuit for controlling the operation of the planar transformer, thereby achieving the above object.

[0031]

FIG. 1 is an explanatory diagram of a method for manufacturing a green tape 1 according to the present embodiment. FIG. 2 is a cross-sectional view of the green tape 1 according to the present embodiment. FIG.
1 is a cross-sectional view of a multilayer ceramic substrate 10 on which a green tape 1 according to the present embodiment is stacked. In the present embodiment, in a multilayer ceramic substrate manufactured by laminating the green tapes 1 having the conductors 12, a multilayer ceramic substrate 10 having no raised portion after lamination is manufactured.

Referring to FIG. 1, a convex molded product 11 has a convex portion 11A. The convex portion 11A is formed on the surface 1 of the convex molded product 11.
It protrudes about D2 = 70 μm from 1B.
The convex portion 11A of the convex molded product 11 is pressed against a soft green tape (ceramic tape) 1 in a direction indicated by an arrow A1. When the protrusion 11A is pressed against the green tape 1, a groove 1A having a depth of about D2 = 70 μm is formed in the conductor printed portion of the green tape 1. If the distance D2 is larger than 70 μm, the thickness D2 of the entire green tape 1 is affected.
It is preferable that 2 = about 70 μm.

A green tape is made by mixing an insulating ceramic and powder called crystallized glass with a resin or a solvent,
This is a ceramic tape having a thickness of about 0.2 mm, which is obtained by shaping the slurry into a sheet shape by a doctor blade method or the like and drying it, and refers to a base portion of a substrate.

Referring to FIG. 2, conductive ink 12 is printed in grooves 1A formed in green tape 1. The conductor (ink) 12 is at a distance D3 more than the surface 1B of the green tape 1.
= 5 to 15 μm. Therefore, the thickness D4 of the conductor (ink) 12 is 55 μm to 65 μm.
m. The thickness D4 of the conductor (ink) 12 is as shown in FIG.
2, the thickness D1 of the conductor 101 described above with reference to FIG.
(about 20 μm to about 20 μm). Therefore, the green tape 100 described above with reference to FIG.
A more uniform green tape 1 can be obtained.

The conductor (ink) 12 is printed so that the distance D3 is about 5 μm to 15 μm lower than the surface 1B of the green tape 1, so that the conductor (ink) 12 does not leak from the groove 1A. Therefore, bleeding of the conductor (ink) 12 can be prevented. Further, variation in the width of the conductor (ink) 12 can be reduced.

Referring to FIG. 3, green tape 1 on which conductor (ink) 12 is printed is laminated to form multilayer ceramic substrate 10. Since the multilayer ceramic substrate 10 is formed by laminating the green tape 1 that is more uniform than the green tape 100 described above with reference to FIG. 12, the surface printing after lamination is stable. For this reason, it is possible to obtain a good printed pattern of the conductor 12 without printing blur or blur.

A method of manufacturing a planar transformer using the multilayer ceramic substrate 10 according to the present embodiment will be described with reference to FIGS. FIG. 4 is an explanatory diagram of a method for laminating the green tape 1 according to the present embodiment. FIG.
Sheet type coil laminate (Coil substrate with built-in ceramic) 2
The appearance of is shown. FIG. 6 is an explanatory diagram showing a state in which a sheet-type coil laminate (a coil substrate with a built-in ceramic) 2 is sandwiched between ferrite cores 3. FIG. 7 shows the appearance of the planar transformer.

The planar transformer is a switching power supply transformer formed by using a conductor pattern of a multilayer substrate.

Referring to FIG. 4, a primary coil, a control unit pattern and a connection via are formed at predetermined positions on green tape 1 constituting a multilayer ceramic wiring board by printing.

Referring to FIG. 5, a sheet-type coil laminated body (coil substrate with a built-in ceramic) 2 is formed by laminating and firing a plurality of green tapes 1 each having a primary coil, a control section pattern, and a connection via formed thereon. create. Since the multilayer ceramic substrate 10 is formed by laminating the green tape 1 that is more uniform than the green tape 100 described above with reference to FIG. 12, the surface printing after lamination is stable. For this reason, it is possible to obtain a good printed pattern of the conductor 12 without printing blur or blur.

Since the thickness of the green tape 1 is kept more uniform than that of the green tape 100 described above with reference to FIG. 12, the occurrence of cracks during firing (about 800 ° C.) is prevented.

At the center of the coil formed on the green tape 1, a hole 2A for passing the ferrite core 3 is formed. As the multilayer ceramic substrate, a glass-based low-temperature firing type substrate is used. The total number of substrates is determined by the number of pattern turns, pattern width, and coil size. For example, 5
For a 0W class switching power supply application, two layers of 3.5-turn coils per layer are stacked.

Referring to FIGS. 8 and 9, examples of the shape of the coil pattern will be described. FIG. 8 is a plan view of the green tape on which the 5-turn coil pattern according to the present embodiment is formed. FIG. 9 is a plan view of the green tape on which the 3.5-turn coil pattern is formed.

Referring to FIG. 8, five-turn conductor pattern 4 is formed on the surface of green tape 1. The conductor pattern 4 corresponds to a primary coil. Referring to FIG. 9, 3.5-wound conductor pattern 5 is formed on the surface of green tape 1. The conductor pattern 5 corresponds to a secondary coil. However, FIGS. 8 and 9 show a general shape of the coil pattern, and the present invention is not limited to this.

Referring to FIGS. 6 and 7, sheet-type coil laminate 2 is sandwiched between two ferrite cores 3 to complete planar transformer 40. Planar transformer 40
Is a sheet-type coil laminate 2 formed by a green tape 1 in which the thickness D4 of the conductor 12 is about four times as thick as the thickness D1 (= about 10 μm to 20 μm) of the conductor 101 described above with reference to FIG. Is used. Therefore, as the planar transformer 40 for the switching power supply, it is possible to obtain a transformer coil having a resistance value of about 1/4 (about 1.4 ohm) in the coil section.

FIG. 10 is a circuit diagram of a switching power supply 30 equipped with the sheet-type coil laminate (coil substrate with a built-in ceramic) 2 according to the present embodiment. FIG. 11 shows the appearance of a switching power supply 30 on which the sheet-type coil laminate (coil substrate with a built-in ceramic) 2 is mounted.

Referring to FIG. 11, switching power supply 30
Is a planar transformer 4 including a sheet-type coil laminate (coil substrate with a built-in ceramic) 2 and a ferrite core 3.
0 is provided.

Referring to FIG. 10, switching power supply circuit 30A includes a primary transformer coil 18, a secondary transformer coil 19, and a control transformer coil 20.

The primary transformer coil 18 corresponds to the primary coil (the conductor pattern 4 shown in FIG. 8) formed on the sheet coil laminate 2, and the secondary transformer coil 19 is the sheet coil laminate 2 The secondary side coil formed in FIG.
(5).

When the AC power supply 151 is turned on, the AC voltage is rectified by the primary side rectifying and smoothing circuit 152 to become a DC voltage, which is supplied to the switching element 156. The DC voltage rectified by the primary side rectifying and smoothing circuit 152 is simultaneously supplied to the auxiliary power supply circuit 153.

As a result, the potential of the electrolytic capacitor in the auxiliary power supply circuit 153 gradually rises, and the PWM control circuit 154
The PWM control circuit 154 starts operating when the operation start voltage reaches the operation start voltage. When the PWM control circuit 154 starts operating, the switching element 156 turns on and off, outputs an AC voltage to the secondary winding 19 and the tertiary winding 20 of the transformer 157, and outputs a load via the secondary-side rectifying / smoothing circuit 155. , And a voltage is supplied to the auxiliary power supply circuit 153 to keep the PWM control circuit 154 in operation.

As described above, according to the present embodiment, the thickness D4 of the conductor (ink) 12 is about four times as thick as the thickness D1 of the conventional conductor 101 (= about 10 μm to 20 μm). Therefore, a green tape 1 that is more uniform than the conventional green tape 100 can be obtained.

Further, according to the present embodiment, since the multilayer ceramic substrate 10 is formed by laminating the green tapes 1 more uniform than the conventional green tape 100, the surface printing after lamination is stable. For this reason, it is possible to obtain a good printed pattern of the conductor 12 without printing blur or blur.

Further, according to the present embodiment, the conductor (ink) 12 has a distance D3 =
Since it is printed so as to be lower by about 5 μm to 15 μm,
The conductor (ink) 12 does not leak from the groove 1A. Therefore, bleeding of the conductor (ink) 12 can be prevented. Further, variation in the width of the conductor (ink) 12 can be reduced.

Further, according to the present embodiment, the thickness of the green tape 1 is kept more uniform than that of the conventional green tape 100, so that the occurrence of cracks during firing (about 800 ° C.) is prevented.

Further, according to the present embodiment, as the planar transformer 40 for the switching power supply, it is possible to obtain a transformer coil in which the resistance of the coil section is about 1/4 (about 1.4 ohms) of the related art.

Further, according to the present embodiment, it is possible to obtain a transformer coil in which the resistance value of the coil section is about 1/4 (about 1.4 ohms) of the related art, so that heat loss due to current is reduced. As a result, the efficiency of the switching coil is about 5
%improves.

[0058]

As described above, according to the present invention, it is possible to provide a method of manufacturing a green tape, a multilayer ceramic substrate, a planar transformer, a switching power supply, and a green tape in which the width of the conductor is small.

Further, according to the present invention, it is possible to provide a method of manufacturing a green tape, a multilayer ceramic substrate, a planar transformer, a switching power supply, and a green tape in which the conductor does not bleed during printing of the conductor.

Further, according to the present invention, there is provided a green tape which does not cause blur when printing on the surface of the multilayer ceramic substrate and does not crack when firing.
A method for manufacturing a multilayer ceramic substrate, a planar transformer, a switching power supply, and a green tape can be provided.

Further, according to the present invention, it is possible to provide a method for manufacturing a green tape having a thick conductor, a multilayer ceramic substrate, a planar transformer, a switching power supply, and a green tape.

Another object of the present invention is to provide a method of manufacturing a green tape, a multilayer ceramic substrate, a planar transformer, a switching power supply, and a green tape having a low resistance value of a coil portion.

Further, according to the present invention, it is possible to provide a method of manufacturing a green tape, a multilayer ceramic substrate, a planar transformer, a switching power supply, and a green tape, in which heat loss due to electric current is small.

[Brief description of the drawings]

FIG. 1 is an explanatory diagram of a method of manufacturing a green tape according to an embodiment.

FIG. 2 is a cross-sectional view of the green tape according to the embodiment.

FIG. 3 is a sectional view of a multilayer ceramic substrate on which a green tape according to the present embodiment is laminated.

FIG. 4 is an explanatory diagram of a method for laminating a green tape according to the present embodiment.

FIG. 5 is a perspective view of a sheet-type coil laminate (coil substrate with a built-in ceramic) according to the present embodiment.

FIG. 6 is an explanatory diagram of a state where a sheet-type coil laminate (a coil substrate with a built-in ceramic) according to the present embodiment is sandwiched between ferrite cores.

FIG. 7 is a perspective view of a planar transformer according to the present embodiment.

FIG. 8 is a plan view of a green tape on which a 5-turn coil pattern according to the present embodiment is formed.

FIG. 9 is a plan view of a green tape on which a 3.5-turn coil pattern according to the present embodiment is formed.

FIG. 10 is a circuit diagram of a switching power supply equipped with a sheet-type coil laminate (a coil substrate with a built-in ceramic) according to the present embodiment.

FIG. 11 is a perspective view of a switching power supply equipped with a sheet-type coil laminate (a coil substrate with a built-in ceramic) according to the present embodiment.

FIG. 12 is a cross-sectional view of a conventional green tape.

FIG. 13 is a cross-sectional view of a conventional multilayer ceramic substrate on which green tapes are laminated.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 Green tape 2 Sheet-type coil laminated body (coil board with a built-in ceramic) 3 Ferrite core for transformer 4 5 winding conductor pattern 5 3.5 winding conductor pattern 10 Multilayer ceramic substrate 18 Primary transformer coil of switching power supply 19 Switching power supply 2 Secondary transformer coil 20 Control transformer coil for switching power supply

Claims (12)

[Claims] 1. A method for manufacturing a green tape on which a conductive ink is printed, comprising: a first step of forming a groove in a conductive printing portion on a surface of the green tape; and a second step of printing a conductive ink in the groove. The method of manufacturing a green tape, wherein the first step includes a third step of pressing a convex portion of the convex molded product against a surface of the green tape. 2. The green according to claim 1, wherein the third step includes a step of pressing the convex portion against the surface of the green tape such that the depth of the groove is substantially 70 μm. Tape manufacturing method. 3. The method according to claim 1, wherein the second step includes printing the conductive ink such that the surface of the conductive ink is lower than the surface of the green tape. . 4. A green tape on which a conductive ink is printed, wherein the green tape has a groove formed in a conductive printing portion on a surface of the green tape, and a conductive ink printed on the groove. A green tape, wherein the conductive ink is printed such that the surface of the conductive ink is lower than the surface of the green tape. 5. The method according to claim 1, wherein the conductive ink is 5 μm thicker than the surface.
The printing is performed so as to be lower by about m to 15 μm.
The described green tape. 6. A multilayer ceramic substrate on which a green tape on which a conductive ink is printed is laminated, wherein the green tape has a groove formed in a conductive printing portion on a surface of the green tape, and a green tape printed on the groove. A conductive ceramic ink, wherein the depth of the groove is substantially 70 μm. 7. The conductor ink is printed such that the thickness of the conductor ink is about 55 μm to 65 μm.
The multilayer ceramic substrate according to claim 6. 8. A coil substrate with a built-in ceramic on which a green tape on which a conductive ink is printed is laminated, wherein the green tape is formed in a groove formed in a conductive printing portion on a surface of the green tape, and is printed in the groove. And a coil formed on the surface of the green tape. 9. The coil includes a primary coil, a secondary coil, and a control coil, wherein the primary coil includes a five-turn coil stacked in ten layers, Each of the side coil and the control coil is
9. The method according to claim 8, comprising a 3.5-turn coil stacked in two layers.
The described ceramic built-in coil substrate. 10. The coil substrate with a built-in ceramic according to claim 9, wherein the green tape is made of a glass-based low-temperature firing type base material. 11. A planar transformer having a coil board with a built-in ceramic and a ferrite core, wherein the coil board with a built-in ceramic is formed by laminating a green tape on which a conductive ink is printed. A planar transformer, comprising: a groove formed in a conductor printing portion on the surface of the green tape; conductive ink printed on the groove; and a coil formed on the surface of the green tape. 12. A switching power supply comprising: the planar transformer according to claim 11; and a control circuit that controls an operation of the planar transformer.