JPH0135483B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an open magnetic path type laminated coil or transformer.

The present inventors have recently proposed a method for manufacturing a laminated coil or transformer by alternately printing and laminating magnetic layers and conductors. This method uses a paste of magnetic ferrite powder, Pd-Ag,
A magnetic layer is printed using a paste of conductor powder such as Pd or Ag, a conductor is printed on top of it in a shape that can form a coil, a magnetic layer is printed on top of that, and the lower conductor is printed. Most of the pattern is covered, and then the next conductor pattern is printed over it to form a continuous coil forming pattern on the underlying conductor, and the printing stack is repeated. The advantages of this method are that a laminated coil or transformer is obtained which has a monolithic integral structure, is small in size, is convenient for soldering, the characteristics can be changed considerably by adjusting the number of laminated layers, and the process can be made consistent.

An object of the present invention is to provide an open magnetic path type laminated coil or transformer by applying the above technology.

Generally, when a high L value is desired, it is better for the magnetic path of a coil or transformer to have as little magnetic resistance as possible. However, closed magnetic circuit coils or transformers are undesirable for some applications because they saturate quickly with respect to excitation current, and are similarly unstable with respect to temperature. On the other hand, although the open magnetic path type coil or transformer has a lower L value than the open magnetic path type coil or transformer, it is less likely to be saturated with the excitation current, has a wider linear range, and has better temperature characteristics.

The present invention provides a laminated coil or transformer,
An open magnetic path type laminated coil or transformer can be provided by simply configuring one layer or a few layers near the midpoint of the laminated body from a nonmagnetic insulator. The laminate is fired at high temperatures before being made into a finished product, but if the thermal shrinkage rates of the insulator and the magnetic material differ too much during this process, it may cause cracks, so it is recommended as a material for the non-magnetic insulator layer. For example, it is preferable to make a paste using powder of ZnO--Bi ₂ O ₃ --CuO-based ceramic material and print the paste to produce the insulating layer.

Embodiments of the invention will now be described in detail with reference to the drawings. Note that although the following description is limited to laminated inductors, it is clear that the present invention can be implemented similarly for laminated transformers.

FIG. 1 shows a magnetic layer 1 in which magnetic ferrite powder is appropriately kneaded with a binder to form a paste and printed in the form of a sheet. In this case, the illustrated magnetic layer 1 represents one of the magnetic layers printed at the same time, or represents one section of a large-area magnetic sheet. In the latter case, the cutting into sections shall be carried out either before or after firing. However, in the following explanation, only one section will be explained for convenience of explanation.

After printing the magnetic layer 1 as shown in Figure 1, next
A conductor 2 is formed by printing a conductive paste in which metal powder such as Pd-Ag is kneaded in a binder and is biased towards the upper side of the magnetic layer 1. At this time, one end of the conductor is exposed to the side portion to form a lead-out portion S. Next, as shown in Figure 2, a magnetic layer 3 is printed leaving one end of the conductor 2, and then a conductor 4 connected to the conductor 2 is printed in a hook shape as shown in Figure 3, and then as shown in Figure 4. A magnetic layer 5 is printed leaving one end of the conductor 4 as shown in FIG. 5, and a hook-shaped conductor 6 to be connected to the conductor 4 is printed as shown in FIG. It can be seen that this forms a conductor pattern extending in a spiral shape between the magnetic layers. Next, for example, ZnO−
An insulator layer 7 is printed as shown in FIG. 6 using a paste containing Bi ₂ O ₃ --CuO type ceramic powder, and one end of the conductor 6 is left exposed at this time. Moving to the step shown in FIG. 7, the conductor layer 8 connected to the conductor 6 is printed in a hook shape. In this way, one layer in the stack becomes an insulator layer. Next, as shown in Fig. 8, the magnetic layer 9 is printed again, and the conductor 10 connected to the conductor 8 is printed in a hook shape as shown in Fig. 9, and its end is exposed on the left side of the laminate and pulled out. Let's call it part t. Finally, as shown in FIG. 10, a magnetic layer is printed on the entire surface to complete the lamination. The thus obtained laminate is placed in a firing furnace and fired to obtain a sintered body. Since the lead-out parts s and t of the conductor are exposed on the sintered body, as shown in Fig. 11, conductive paste (paste of powder of silver, copper, etc.) is applied and baked to form external terminals 12 and 13, and the finished product is completed. It is considered as a product.

FIG. 12 is a schematic diagram of the obtained laminated coil, in which the magnetic flux φ is due to the magnetic layers 1 and 11.
hardly leaks to the outside of the laminate. However, due to the presence of the insulator layer 7, a gap-equivalent portion is formed as indicated by diagonal lines in FIG. 12, resulting in an open magnetic path type laminated coil. Therefore, DC superimposition characteristics, temperature characteristics, etc. are significantly improved.

Note that although the above example is an example of an inductor, it is also easy to configure an open magnetic path type laminated transformer by doubling the printing of the conductor.

In addition to the above-mentioned excellent characteristics, the open magnetic path type laminated coil of the present invention has many advantages, such as being in the form of a chip, being small, easy to attach to a printed circuit board with external terminals, and being able to be manufactured through an integrated process. has advantages.

[Brief explanation of drawings]

1 to 10 are plan views showing the sequential steps for manufacturing an open magnetic path laminated coil according to an embodiment of the present invention, and FIG. 11 is a perspective view of the completed open magnetic path laminated coil, and FIG. FIG. 12 is an explanatory diagram schematically depicting the laminated coil of FIG. 11. The main parts in the figure are as follows. 1, 3, 5, 9, 11: magnetic layer, 2, 4,
6, 8, 10: Coil forming conductor, 7: Nonmagnetic insulator layer, 12, 13: External terminal.

Claims (1)

[Scope of Claims] 1. Printed magnetic layers and approximately half turns of printed conductors are alternately laminated, and the ends of each conductor are connected at the edge of the magnetic layer, so that the conductor is connected to the magnetic layer. In an integrally sintered laminated coil in which one or more coils are formed between the layers, an open magnetic path laminated coil is characterized in that a nonmagnetic insulating layer is interposed between the magnetic layers. coil. 2 The nonmagnetic insulator layer is ZnO-Bi ₂ O ₃ -CuO
2. The laminated coil according to claim 1, which is made of ceramic.