JPH0443404B2 - - Google Patents

Description

[Detailed Description of the Invention] [Summary] A method for manufacturing a magnetic molded coil, in which a winding wire is fitted onto a core of a molding die, and the outside thereof is molded with a magnetic molding material to form an outer core. After that, the core is removed, and the inner core is inserted and fixed into the hollow space created by removing the core to form a coil with a closed magnetic circuit configuration. The influence of contraction pressure can be avoided, and deterioration of magnetic properties can be prevented.

[Industrial application field]

The present invention relates to a method for manufacturing a chip-type magnetic molded coil to be mounted on a printed wiring board of an electronic device.

In recent years, electronic devices have become smaller and more dense, and along with this, the electronic components mounted on printed wiring boards have also become smaller and have changed from the conventional leaded type to leadless chip type. ing.

[Conventional technology]

Conventional molded coils are made by directly winding a wire around a drum-shaped ferrite core, and then integrally molding the core with plastic molding material.

[Problem that the invention seeks to solve]

In the conventional molded coil described above, the core is subjected to high temperature and pressure during molding and shrinkage pressure of the molding material, which sometimes causes deterioration in the magnetic properties of the core. (For example, a decrease in μe) Also, since it has an open magnetic circuit configuration, the outer dimensions become large because a thin wire is wound many times in order to realize a large inductance. DC resistance increases. It is difficult to improve Q characteristics. There were other drawbacks.

The present invention was created in view of the above points, and an object of the present invention is to provide a method for manufacturing a magnetic molded coil that can obtain a compact molded coil with excellent characteristics.

[Means for solving problems]

For this reason, the present invention provides a method for manufacturing a magnetic molded coil, which includes at least a. fitting the winding 1 into the core of a molding die, molding the outside with a magnetic molding material, and then step of removing the outer core 2 and integrally molding the outer core 2; b. Next, metal foil 3 is placed on both end surfaces of the outer core 2 obtained by the above molding, and the winding end 1a is soldered to the metal foil 3. c. Next, inserting and fixing the inner core 4 into the hollow part 2a created by removing the core of the outer core 2; d. Further attaching the terminal fittings 5 to both ends of the outer core 2, and winding the inner core 4. By performing the steps of connecting to the end 1a in this order, a chip-shaped molded coil is manufactured so that the molding pressure, high temperature, and shrinkage pressure during molding of the outer core 2 are not applied to the inner core 4. .

[Effect]

When manufacturing molded coils, the internal core material is exposed to high temperatures and
Since high pressure and shrinkage pressure of the molding material are not applied, there is no deterioration in the characteristics, and the closed magnetic circuit configuration makes it possible to improve the characteristics.

〔Example〕

FIG. 1 is a diagram for explaining an embodiment of the present invention, and a to e are manufacturing process diagrams thereof. In the figure, 1 is a winding, 2 is an outer core, 3 is a metal foil, and 4 is a winding.
5 is an inner core, and 5 is a terminal fitting.

The method of this embodiment will be explained with reference to FIG. 1. First, a winding 1 is formed as shown in FIG. a. Next, as shown in Figure b, insert the core of a mold into the winding 1 so that the inside of the winding 1 is hollow, and after molding the outside with a magnetic molding material, remove the core. It is removed and the outer core 2 is integrally molded. Next, as shown in Figure c, metal foils 3 are placed on both end faces of the outer core 2, and the winding ends (leads) are soldered to the metal foils 3. Next, as shown in Figure d, the inner core 4 is inserted into the hollow part 2a created by removing the core of the outer core 2, and fixed with an adhesive or the like. In this case, the outer diameter of the inner core is smaller than the inner diameter of the winding 1, and the length may be such that it can fit into the outer core. Finally, as shown in figure e, after attaching the terminal fittings 5 to both ends of the outer core 2,
Complete by soldering to the end of the winding.

In this way, the magnetic molded coil formed by this method can sufficiently suppress the deterioration of the characteristics of the inner core, which is particularly important in reducing the size of the coil.
Furthermore, the inductance can be adjusted by adjusting the length of the inner core and the position of the winding.

〔Effect of the invention〕

As described above, according to the present invention, it is possible to obtain a magnetic molded coil that can be downsized and have improved characteristics, and is extremely useful in practice.

[Brief explanation of the drawing]

FIG. 1 is a diagram for explaining an embodiment of the present invention, and a to e are process diagrams thereof. In FIG. 1, 1 is a winding, 2 is an outer core made of magnetic molding material, 3 is a metal foil, 4 is an inner core,
5 is a terminal fitting.

Claims (1)

[Scope of Claims] 1. A method for manufacturing a magnetic molded coil, comprising at least: a) fitting the winding 1 into the core of a molding die, molding the outside with a magnetic molding material, and then placing the winding 1 into the core; step of removing and integrally molding the outer core 2, b. Next, metal foil 3 is placed on both end surfaces of the outer core 2 obtained by the above molding, and the winding end 1a is soldered to the metal foil 3. Step c: Then, inserting and fixing the inner core 4 into the hollow part 2a created by removing the core of the outer core 2; d: Further attaching the terminal fittings 5 to both ends of the outer core 2, and attaching the terminal fittings 5 to the winding ends 1a. In the connecting process, the outer core 2 is connected to the inner core 4.
A method for manufacturing a magnetic molded coil, characterized in that a chip-shaped molded coil is manufactured by avoiding the application of mold pressure, high temperature, and shrinkage pressure during molding.