JPS6346566B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a laminated transformer, and more particularly to a transformer in which a thin layer of insulator and at least two sets of conductive patterns for coils are laminated.

A conventional transformer consists of a magnetic core having an E-I shape, an E-shape, an E-Y shape, etc., and an insulated conductor wire wound around any leg of the core to form a pair of coils. However, the transformer using this method requires a complicated winding process, and the manufactured transformer becomes large.

The present inventors proposed a method of manufacturing an inductor using a lamination method in Japanese Patent Application No. 161,221/1983 in order to solve the problems of the conventional inductor using a wire-wound method. To summarize, a conductive pattern for an inductor is printed on a thin insulating substrate, an insulator layer is further laminated on top of that, a conductive pattern for an inductor is printed, and the lamination process is repeated in the same way. A chip-shaped laminate was formed, this was fired, and a terminal electrode was baked on the edge of the laminate so as to be connected to the end of the conductor pattern exposed at the edge of the laminate. This method provided benefits such as miniaturization of composite parts, mass production, and cost reduction.

The present inventors recognized that the above-mentioned technique can also be used in transformers by taking appropriate measures, and provided the laminated transformer of the present invention.

It is an object of the present invention to provide a laminated chip transformer by alternately laminating thin layers of magnetic insulator (preferably insulating magnetic ferrite) and at least two sets of conductive patterns for coils. do.

The laminated transformer of the present invention is manufactured using printing technology, and the resulting component constitutes a transformer in which two sets of conductive patterns for coils constitute a continuous conductor that circulates from layer to layer of laminated magnetic insulators. Moreover, it has a small and monolithic structure.
Laminated transformers can be manufactured in large numbers at the same time through a consistent printing and laminating process, making it possible to stabilize quality and mass-produce. In addition, the small, chip-shaped laminated transformer of the present invention also has assembly advantages such as ease of attachment to a printed circuit board or the like.

The invention will be explained in detail below in conjunction with the drawings.

The magnetic insulator used in the present invention is an insulating magnetic ferrite powder selected according to the application, made into a paste with an appropriate binder (butyral resin, methyl ethyl cellulose, etc.), and then printed as a paste ink. Formed on a thin layer (hereinafter referred to as printing method). These are later fired. The conductive pattern for the electrode layer and coil used in the present invention is obtained by forming a paste of metal powder such as Pd, Ag-Pd, etc. with a suitable binder into a thin plate shape by a printing method. It is preferable to use heat-resistant metal powder such as Ag--Pd for electrodes and other conductors that undergo firing at high temperatures, and to form terminal electrodes using conductive metal powder such as Ag.

1 to 7 show the laminated transformer of the present invention and its manufacturing process. FIG. 1 explains a practical method for carrying out the present invention. First, a base film such as polyethylene terephthalate (not shown) is used.
is prepared, and a thin plate (film)-shaped magnetic insulating layer 1 is printed on it.

Referring again to FIG. 1, the magnetic body 1 is connected to lines a and b.
However, in reality, these lines are imaginary, and each layer is formed following the magnetic material 1, and cut along these lines with an appropriate cutter before and after. Hereinafter, in order to simplify the explanation, only one section of the laminated composite component will be explained.

FIG. 2 shows one section of the insulator layer shown in FIG.
A pair of hook-shaped coil conductive patterns 2 and 3 are printed on the surface of the insulating layer 1. conductive pattern 2,
3 extends to the lower side of the insulating layer 1 at its ends 4 and 5, and its inner ends 6 and 7 terminate in close proximity. The gap g between the inner ends 6 and 7 is appropriately determined depending on the coupling coefficient k of the intended laminated transformer. Moving to the process shown in FIG. 3, rectangular insulating layers 8 and 9 are laminated by printing onto the underlying conductor pattern and insulating layer. At that time, the end 6 of the lower conductive pattern,
7 are left exposed and used as connecting portions of the conductive pattern. Next, as shown in FIG. 4, conductive patterns 10 and 11 for forming coils are printed. The conductive patterns 10 and 11 are U-shaped, and their inner parts are arranged close to each other, and their inner ends have connecting parts 14 and 15 that overlap with the connecting parts 6 and 7 of the lower conductive pattern. The outer ends 12 and 13 extend toward the upper side of the stack. As can be seen from the above description, the conductor patterns 2 and 10 form a first set of continuous circuit patterns to form the first coil, and the conductor patterns 3 and 11 form a second set of continuous circuit patterns. forming a second coil. The ends of each coil are exposed on the lower and upper sides of the stack. Although the number of laminated layers is limited to simplify the explanation, it is also within the scope of the present invention to repeat the steps shown in FIGS. 2 to 4 as many times as necessary depending on the purpose. Next, as shown in FIG. 5, an insulating layer 16 is laminated by printing to cover the entire surface of the lower layer. Finally, individual laminates are obtained by cutting the laminate along lines a and b, as described in connection with FIG.
5, 12, and 13 are exposed. The thus obtained laminate is fired in a firing furnace to obtain an integral chip-shaped laminate in which each layer is firmly bonded. Next, as shown in FIGS. 6 and 7, the terminal electrode 1 is made of silver paste, etc.
7, 18, 19, and 20 are applied or printed so as to connect to the ends 4, 5, 12, and 13 of the conductive pattern, respectively, and to extend at least between the upper and lower ends of the side surface of the laminate, and then baked at an appropriate baking temperature. These terminal electrodes are baked into the laminate. It will be clear that the completed laminated transformer has the equivalent circuit shown in FIG.

As described above, since the laminated transformer of this embodiment is manufactured using the printing method, it has the above-mentioned advantages of the printing method. Furthermore, by appropriately adjusting the gap between the two sets of coils during manufacturing, a transformer with a desired coupling coefficient can be obtained. The finished laminated transformer is strong and compact, and can be directly attached to a printed wiring board as a leadless component by using external film terminal electrodes.

Next, a laminated transformer according to a second embodiment of the present invention will be described. FIG. 9 shows one of the sections having the same arrangement as in FIG. 1. First, an L-shaped first
Print a conductive pattern 22 for forming a coil. One end of the conductive pattern 22 is exposed at the lower side of the insulating layer 21, and the inner end is terminated at the connection portion 24. Moving on to the step shown in FIG. 10, the left side of the magnetic insulating layer 21 and the conductive pattern, leaving the connecting portion 24, is covered with a magnetic insulating layer 25 by printing. Then the 11th
As shown in the figure, a conductive pattern 26 for forming an L-shaped second coil is formed so as not to interfere with the connection part 24.
is printed. At this time, one end 27 of the conductive pattern 26 is exposed on the upper side of the insulating layer 21, and the inner end is terminated at the connecting portion 28. Next, as shown in FIG. 12, a magnetic insulating layer 29 covering the center portion of the conductive pattern 26 is formed by a printing method, and then, as shown in FIG. 13, a conductive pattern 30 for forming an L-shaped second coil is printed. be done. This conductive pattern terminates at a connecting portion 31 that overlaps the connecting portion 28 of the conductive pattern 26 and a connecting portion 32 at the inner end. As shown in FIG. 14, next, a magnetic insulating layer 33 is formed by a printing method so that the connecting portion 32 remains, and then the first
As shown in FIG. 5, a U-shaped conductive pattern 34 for forming the first coil is printed. One end of the conductive pattern 34 overlaps the connection portion 24 of the lower conductive pattern 22 for forming the first coil, and the other end 36 is exposed on the upper side of the laminate. Next, as shown in FIG. 16, a magnetic insulating layer 37 is coated on the entire surface of the laminate by printing, leaving only the connecting portion 32 of the conductive pattern for forming the second coil, and then as shown in FIG. 17. A conductive pattern 38 is printed. At this time, the connecting portion 39 at one end of the conductive pattern 38 overlaps the connecting portion 32 of the lower conductive pattern, and the other end 40 is exposed at the lower side of the laminate. Next, as shown in FIG. 18, a magnetic insulator layer 41 is formed on the entire surface by a printing method. Once the lamination has been completed up to this stage, the parts are cut into individual parts in the same manner as shown in FIG. 1, and then fired in a firing furnace to form a monolithic fired body. The ends 23 of the conductive pattern for the first coil are on the upper and lower sides of this fired laminate.
36 is exposed, and terminal electrodes 42, 43, 44, 45 are connected to the ends 27, 40 of the second coil conductive pattern, respectively.
burn. The appearance of the laminated transformer completed as described above is as shown in Fig. 18, and this is
It is similar to that shown in FIG. 7 in connection with the embodiment.

It will be clear that the laminated transformer of this embodiment provides similar benefits to the first embodiment. Furthermore, since the two sets of orbiting conductive furnaces (coils) can be overlapped with each other with a magnetic insulator interposed,
Coupling between coils can be enhanced. Although the embodiments of the present invention have been described using two sets of coils, three sets, four sets, etc. may be provided depending on the application.

[Brief explanation of the drawing]

1 to 7 are plan views showing the sequential manufacturing steps of the laminated transformer according to the first embodiment of the present invention, and FIG. 8 is an equivalent circuit diagram of the laminated transformer of the first embodiment.
FIGS. 9 to 18 are plan views showing sequential manufacturing steps of a laminated transformer according to a second embodiment of the present invention. The main members in the figure are as follows. 1, 8, 9, 16: Insulating layer, 2, 10: Conductive pattern for first coil formation, 3, 11: Conductive pattern for second coil formation, 17, 18, 19, 20:
Terminal electrode, 21, 25, 29, 33, 37, 4
1: Insulator layer, 22, 34: Conductive pattern for forming the first coil, 26, 30, 38: Conductive pattern for forming the second coil.

Claims (1)

[Claims] 1. A laminate of a plurality of printed magnetic insulator layers, and at least two sets of printed conductive patterns that are embedded in the laminate and continuously circulate from one layer of the magnetic insulator layer to another, an integral sintered body comprising conductive patterns whose revolving axes are substantially perpendicular to the surface of the magnetic insulating layer; and lead-out portions of these conductive patterns drawn out to side end surfaces of the laminate; A laminated transformer comprising a film-like external terminal having a sufficient area suitable for solder and provided at least between the upper and lower ends of the side end face, covering the lead-out portion of the side end face.