JPH0463404A - Electronic parts and manufacture thereof - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to electronic components such as microinductors and methods of manufacturing the same.

[Summary of the invention]

The present invention aims to create a closed magnetic circuit structure by covering the surface of an element part of an electronic component such as a microinductor with a resin containing ferrite powder, thereby increasing the shielding effect and reducing leakage magnetic flux.

Further, the present invention aims to suppress the generation of stress and its influence on the element portion by curing the resin containing ferrite powder using electromagnetic induction heating using high frequency current.

[Conventional technology]

In electronic components such as inductors, problems such as increased noise, decreased Q and single oscillation are likely to occur due to the influence of leakage magnetic flux. For example, a drum-shaped open magnetic path type inductor has a large leakage magnetic flux, causes noise and interference due to mutual induction, and is often subject to restrictions on its installation position.

Up to now, attempts have been made to reduce the influence of leakage magnetic flux by forming electronic components such as inductors into closed magnetic circuit structures. For example, toroidal type, pot type, E type, U type,
This method uses a C-type core, etc.

However, the former is difficult to wind;
The latter method is disadvantageous in terms of manufacturing cost compared to the open magnetic path structure, and therefore, the adoption of these methods is limited to special cases.

On the other hand, in electronic components such as microinductors, the exterior is generally coated with a powder resin coating, etc., for the purpose of protecting internal elements from outside air, humidity, etc., and for appearance.

However, conventional exterior coatings do not take into consideration the above-mentioned magnetic properties, electrical properties, etc., and do not have any effect of improving the influence of the above-mentioned leakage magnetic flux, for example.

[Problem to be solved by the invention]

Therefore, the present invention has been devised in view of the above-mentioned conventional situation, and provides an electronic component and its manufacturing method that can reduce the influence of leakage magnetic flux without increasing manufacturing difficulties or manufacturing costs. The purpose is to provide.

[Means to solve the problem]

In order to achieve the above object, the electronic component of the present invention is characterized in that an element portion is covered with a resin containing ferrite powder in a proportion of 30 to 97% by weight.

Further, the manufacturing method of the present invention uses ferrite powder of 30 to 9
The present invention is characterized in that after applying a resin containing 7% by weight to the element portion, the resin is cured by electromagnetic induction heating using a high frequency current.

[Effect]

When the element portion of an electronic component is coated with a resin containing ferrite powder, a closed magnetic circuit structure is created, and leakage magnetic flux is reduced due to the shielding effect.

In addition, in the present invention, when curing the resin containing ferrite powder, the eddy current product and hysteresis loss of the ferrite powder are used to generate heat by t magnetic induction caused by high frequency current, so the interior is high and the air is In order to dissipate heat to the outside, a temperature gradient is created that lowers the temperature outside, and the generation of stress is greatly suppressed.

〔Example〕

Examples to which the present invention is applied will be described below.

Fig. 1 shows an embodiment of an electronic component to which the present invention is applied. All but 1a) are covered with a resin layer (2) containing ferrite powder.

The resin layer (2) is made mainly of ferrite powder and resin, with addition of curing agents, accelerators, etc. as necessary, and is applied to the surface of the microinductor (1) by dipping or powder coating techniques. It is made by being attached to.

The ferrite powder contained in this resin layer (2) may be any powder obtained by finely pulverizing various ferrites, such as fine powders of Ni-based, Mg-based, and Mn-based ferrites. It will be done. The ferrite powder used preferably has an average particle size within the range of 1 μm to 1100 tI, and if the average particle size is less than 1 μm, it may become magnetically saturated and a sufficient effect may not be obtained.

In addition, it is more preferable to set it to 50 micrometers or less within the above-mentioned range, but the thing exceeding 100 micrometers can also be used depending on the case.

On the other hand, as the resin, any synthetic resin material such as polyvinyl chloride, polyolefin, epoxy resin, polyester resin, thermosetting acrylic resin, fluororesin, cellulose derivative, etc. can be used, but there are some issues such as ease of handling. Therefore, thermosetting resins are more advantageous than thermoplastic resins.

In particular, epoxy resin is suitable because it has excellent adhesion to various metals, good workability, physical properties, mechanical properties, and chemical properties.

In addition, the amount of ferrite powder contained in the resin is 3
It is preferably 0 to 97% by weight, more preferably 50 to 95% by weight. If the content of ferrite powder is less than 30% by weight, it will be difficult to construct an effective closed magnetic path, and there is a risk that the shielding effect will be insufficient. Conversely, if the content of ferrite powder exceeds 97% by weight, the resin content will be insufficient and it will be difficult to form a coating.

The above-mentioned resin layer (2) can be formed by a normal coating method.For example, a paste-like paint is formed by dissolving a mixture of ferrite powder, epoxy resin, curing agent, and accelerator in a solvent. , this is a microinductor (1
), then blow warm air at about 40°C to volatilize the solvent and dry it. By doing this, the filling rate of the ferrite powder (ratio to the microinductor) can be increased to 80 to 80% by weight. It is possible to increase it to 90%.

In the above method, it is possible to control the viscosity at tJ4 by controlling the amount of solvent, and it is also possible to inject it into a mold to improve workability, but when the solvent evaporates, depletion occurs and the surface becomes rough. There is a rough hole.

Therefore, in order to particularly improve weather resistance, powder coating may be performed.

The outline of the manufacturing process using powder coating is shown below.

To perform powder coating, first, resin (for example, epoxy resin), ferrite powder, additives, etc. are weighed and dry mixed using a ribbon blender or the like.

Next, this is heated to 140-150°C and melt-mixed.

Furthermore, the molten mixture is dropped onto a conveyor to be cooled, and then pulverized using a hammer machine or the like.

Weigh this, add an appropriate amount of epoxy resin curing agent and accelerator, mix it with a narrator, etc., and use a single-shaft mixer etc. to
The mixture is melted and mixed at 00''C, then dropped onto the conveyor again and cooled.

Next, it is pulverized using a fine pulverizer such as a turbo mill, and then classified using a 200 to 400 mesh sieve using a blower lid or the like.

A powder coating is prepared as described above, and on the other hand, the element to be coated [microinductor (1)] is heated at 120 to 130°C for about 1 minute.

Then, the powder paint prepared in the heated state of the microinductor (1) is blown up by air and vibration, and the powder paint is adhered to the surface of the microinductor (1).

Then, the powder paint adhering to the surface of the microinductor (1) is melted by the residual heat of the microinductor (1), forming a film.

By the way, when the resin is heated and cured in the above-mentioned powder coating, the heat source is generally external, so curing starts from the resin surface and progresses to the inside. During this process, curing shrinkage occurs, stress is generated, and electronic For example, the stress may cause wire breakage, cranking, deterioration of characteristics, etc., and cracks, roughness, etc. may occur on the surface of the resin layer (2).

Therefore, it is preferable to use the eddy current product, hysteresis loss, etc. of the ferrite powder to generate heat by magnetic induction in 1 caused by a high-frequency current, and to cure the resin by this heat generation.

FIG. 2 shows an example of a heating curing device using electromagnetic induction.

This heat curing device has a rectangular parallelepiped-shaped hollow magnetic core (3
), a microinductor (1) coated with a resin containing ferrite powder is moved along this slit (4),
The ferrite powder is heated by electromagnetic induction using the magnetic field generated in the slit (4).

That is, a coil (5) is wound around the magnetic core (3), and a high frequency power source (6) is connected to the coil (5).
) is connected, and by supplying a high frequency current from this high frequency power source (6) to the coil (5), the resin containing ferrite powder is hardened by electromagnetic induction heating.

Here, if the microinductor (1) coated with resin containing ferrite powder is supplied in a state fixed to the tape carrier (7), continuous processing becomes possible.

The above-mentioned heat curing device is capable of controlling the eddy current product of ferrite powder,
Since it uses hysteresis loss to generate heat,
The temperature gradient of the resin is high inside and low outside (because heat is dissipated into the air), and the generation of stress is extremely small.

In addition, by selecting the Curie point of the ferrite powder,
The upper limit of heat generation can be determined and abnormal heating can be prevented.

This is because hysteresis loss no longer occurs in the ferrite powder when the Curie point is exceeded.

In addition, as mentioned above! When the resin is cured by magnetic induction heating, a substance that generates heat by high-frequency heating may be mixed in the resin in addition to the ferrite powder.

When a microinductor was actually coated with a ferrite-containing resin according to the above method, a closed Mi path structure was obtained, and the shielding effect was improved by about 6 dB.

Further, when the content of ferrite powder was reduced to 70% by weight, the inductance value of the microinductor was improved by about 1.5 times. This means that for the same inductance value, the DC resistance is reduced by about 20%. Therefore, when the external dimensions are the same, the inductance value can be increased, and when the inductance values are the same, the DC loss is reduced and the efficiency is improved.

Although embodiments to which the present invention is applied have been described above, the present invention is not limited to these embodiments. For example,
In the above example, the surface of the element part (microinductor) of the electronic component was coated only with the resin containing ferrite powder, but especially when using a ferrite powder with low electrical resistance such as Mnn-based tuyurite, the element It is also possible to form an insulating film on the surface of the part in advance by powder coating or the like and then cover it with a resin containing ferrite powder.

〔Effect of the invention〕

As is clear from the above explanation, in the electronic component of the present invention, the surface of the element part is covered with a resin containing ferrite powder, so that it can be effectively It is possible to improve the magnetic permeability, enhance the shielding effect, and reduce the influence of leakage magnetic flux.

In addition, according to the manufacturing method of the present invention, the stress during curing of the resin can be reduced, preventing element disconnection and magnetostriction.
Cracks etc. can be suppressed.

[Brief explanation of the drawing]

FIG. 1 is a schematic plan view showing an embodiment in which the present invention is applied to a microinductor. FIG. 2 is a schematic perspective view showing an example of a heating curing device for curing resin by electromagnetic induction heating. 1...Element part (microinductor) 2...Resin layer Patent applicant Sony Corporation (and others)

Claims (2)

[Claims] (1) An electronic component characterized in that an element portion is covered with a resin containing ferrite powder in a proportion of 30 to 97% by weight. (2) A method for manufacturing an electronic component, which comprises applying a resin containing 30 to 97% by weight of ferrite powder to an element portion, and then hardening the resin by electromagnetic induction heating using a high-frequency current.