JPH0262012A - Inductance element and its manufacture - Google Patents

Abstract

PURPOSE:To obtain a high impedance value and to make this element small- sized and thin by a method wherein a flat square wound coil having no bobbin or no magnetic core is buried in a mixture of a high-permeability magnetic powder and a resin. CONSTITUTION:An in-line winding coil 2, having no core, whose number of turns is about 24 turns is made. After this coil 2 bas been attached to metal sheet terminals to be used as external terminals 3, 4, the coil 2 as a whole is compressed and molded by using a resin ferrite 1. During this process, a high permeability ferrite powder is filled as highly as possible, e.g., 90wt.% or higher, with reference to a resin in such a way that the ferrite 1 of high permeability is obtained after its compression and molding operation. An epoxy- based resin, a nylon-based resin or a polyurethane-based resin is suitable as a main resin. Thereby, a high impedance value is obtained; a small-sized and thin element can be made.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of the Invention The present invention relates to a high-performance coreless inductance element that is compact and suitable for high-density packaging used in various electronic devices, and a method for manufacturing the same.

2. Description of the Related Art A conventional inductance element is made by winding a copper wire 7 having an insulating coating layer around a magnetic core or bobbin 6, and molding the outer periphery with resin or resin ferrite 5, as shown in FIG. In most cases, an external terminal 8°9 is provided to serve as an inductance element. The smallest product of this inductance element currently commercialized is 2.6 L
The size is 2゜0W x 1.8H To 3.

Problems to be Solved by the Invention However, as electronic devices become lighter, thinner, shorter, and smaller, the electronic components used in them are required to be further miniaturized and made into chips.In recent years, in particular, the packaging density of electronic circuits has been dramatically improved. The development and practical application of surface-mounted components that allow However, inductance elements cannot be used with other passive chip components such as resistor elements and capacitors (all of which have a minimum of 1.
6LXo, 8WX0.4H), the development of smaller chips has been delayed.

The main reason for this is that most inductance elements are constructed using either a bobbin (core) for winding the coil or a magnetic core made of a high permeability magnetic material to further improve the characteristics. Therefore, there is a limit to miniaturization, and even if the winding core is made smaller, the yield in the winding and assembly process will decrease, resulting in lower productivity.
This caused problems in terms of cost.

In this way, a structure for making the inductance element even smaller without deteriorating its characteristics is being sought. For example, a ferrite sintered multilayer chip inductance element, which is said to be more compact than the wire-wound inductance element described above, has been proposed (see Japanese Patent Publication No. 67-39521) and has been put into practical use (minimum product 2. 0LX1.2"Xo, 8
H@'). However, even with this configuration, the precise printing process,
There are still problems in terms of yield and manufacturing cost due to high temperature firing and the use of expensive noble metal conductive materials.

In view of the above problems, the present invention provides a conventional wire-wound type inductance element.

Means for Solving the Problems In order to solve the above problems, the inductance element of the present invention is made by preparing a coreless (no bobbin) winding coil made of rectangular conductive wire in an aligned manner, and then winding it with a soft magnetic material of high magnetic permeability. The structure is such that it is embedded in a mixture of powder and resin.

In this manufacturing method, a rectangular conductive wire with a predetermined cross-sectional dimension is used to create a coreless coil that is wound in a desired diameter and number of turns, and this coil is attached to a metal plate terminal that serves as an external terminal. After that, the above-mentioned wire-wound coil is compression molded into the desired size and shape using a mixture of high permeability magnetic powder and resin to embed it, and the metal plate terminals exposed to the outside are molded to form external terminals. It is processed.

Function: In the inductance element configured as described above, since no winding core is used, the size of the inductance element can be determined by the height of the coil itself. Therefore, the device can be made smaller and thinner, and has a simpler structure, which simplifies the process, improves yield, and significantly reduces manufacturing costs.

In addition, in the case of the wire-wound inductance element, which is already in practical use and whose exterior is molded and sealed with resin ferrite, compression molding cannot be used when sealing the coil with resin ferrite because of the core. The transfer molding method, which is a type of injection molding method, is used. Therefore, in this method, since a certain amount of flow of the resin ferrite is required during molding, there is a limit to increasing the content of ferrite powder in the resin ferrite. As a result, resin ferrite cannot be expected to significantly improve the characteristics of an inductance element.

However, according to the method of the present invention, since no winding core is used, the ferrite powder content in the resin ferrite can be increased to 90 wt% or more, and since the coil is an aligned winding coil using a rectangular conducting wire, the pressure is high. Even with compression molding, there is no change in the shape of the coil or round wire that occurs when round conductors are used, so stable high compression molding is possible, resulting in high inductance for an inductance element that does not use a magnetic core. It has the advantage that a high Q value can be obtained.

Furthermore, since the inductance element of the present invention structurally covers the coil portion with a homogeneous high permeability resin magnetic material,
It is also excellent as an inductance element for high-density packaging and high-frequency bands, as magnetic flux does not leak outside and there is no risk of crosstalk, and it is also suitable as an electromagnetic noise countermeasure component, which has recently become a hot topic.

EXAMPLE An example of the present invention will be described below with reference to FIG. 1, but it goes without saying that the inductance element is not limited to a single coil body, but also includes a transformer type or an inductance network consisting of a plurality of coils. .

Here, a case will be described in which high magnetic permeability ferrite powder is used as an example of the magnetic powder.

First, organic insulation coated 0, 037IOIIX 0
．． Winding diameter using 09mm mm wire: 0.6rtan
First, a coreless aligned winding coil 2 with φ1 number of turns: 24 turns is created. After attaching this coil 2 to the metal plate terminals that will become the external terminals 3 and 4, the entire coil 2 is attached to the resin ferrite 1.
3.2L at a pressure of 2t/C14 from the arrow direction in Figure 1.
Compression molding to a size of X1.6 W
As described above, the resin ferrite layer 1 after compression molding is made to have high magnetic permeability. As the main resin, other resins with good processability such as epoxy resin, polyurethane resin, acrylic resin, nylon resin, phenol resin, polyester resin, etc. are suitable, but here we will focus on improving heat resistance. A thermosetting epoxy resin was used. After compression molding, the product was cured for 180°C3o minutes, and the metal plate terminals exposed to the outside were bent along the sides of the molded chip as shown in FIG. 1 to produce an inductance element as external terminals 3.4.

As a comparative product, the same coreless coil as above was sealed with resin ferrite by transfer molding to produce inductance elements of the same size, and the inductance value and Q value of each were measured and shown in the table below.

In the above example, an inductance element was made in the same way using a round copper wire with a diameter of 0.03 mm, but when the compression molding pressure exceeded 6t/cJ, the coils wound in alignment began to shift by 1t/cJ. At C- or above, the L value and Q value actually worsened.

(Left below) Effects of the Invention As described above, according to the present invention, the inductance element in which the entire rectangular winding coil without a core is compressed and embedded with a resin magnetic material has a high Q1 high inductance value, Moreover, it can produce many excellent effects such as being able to be made smaller and thinner.

[Brief explanation of the drawing]

FIG. 1 is a sectional view of a resin ferrite-embedded coreless inductance element according to an embodiment of the present invention, and FIG. 2 is a sectional view of a typical conventional drum core magnetic core type inductance element. 1... Resin ferrite, 2... Rectangular winding coil, 3.4... External terminal.

Claims (2)

[Claims] (1) An inductance element in which a rectangular winding coil without a bobbin or magnetic core is embedded in a mixture of high magnetic permeability magnetic powder and resin. (2) Create an aligned winding coil without a bobbin or magnetic core using rectangular conductive wire, attach it to a metal plate terminal that will serve as an external terminal, and then wrap the coil with a mixture of high permeability magnetic powder and resin. A method of manufacturing an inductance element, in which the inductance element is compressed into a desired size and shape so as to be buried, and the exposed metal plate terminal is processed to become an external terminal.