JPH01321607A - Inductance element and manufacture thereof - Google Patents

Abstract

PURPOSE:To make it possible to obtain an inductance element which is a further miniaturized and thinned closed magnetic circuit type by constituting ferrite powder to be mingled in resin out or powder having specific particle diameters, and sealing it with resin to which this ferrite powder is mingled. CONSTITUTION:Ferrite powder consisting of powder having particle diameters of 20-210mum for the most part is mixed and kneaded with synthetic resin 7, and this mixed and kneaded substance is used to seal a core vacant coil 5 or a magnetic core contained coil 5 and these are solidified as occasion demands. For the ferrite powder, the coercive force lowers as the particle diameter becomes large, and the powder having large particle diameters is excellent as soft magnetic material compared with powder small in particle diameter. Hereby, as compared with the case that the conventional ferrite powder is used, it can improve inductance L more than 10%, if selecting conditions, more than 70%. Also, in case that the inductance L is made to be equal, it can make small the size of the element, especially the height more than 10%, if selecting conditions, more than 70%.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of the Invention The present invention relates to an inductance element used in various electronic devices and a method for manufacturing the same.

2. Description of the Related Art As shown in FIG. 5, a conventional inductance element is made by winding a copper wire 2 having an insulating coating around a magnetic core or an air-core bobbin 1 and connecting it to a terminal 3 to form a coil. The wire-wound type, which is sealed and molded using Step 4, is the mainstream.

In recent years, as electronic devices have become lighter, thinner, shorter, and smaller, electronic components have become more densely packaged, and there is a strong demand for smaller and thinner electronic components.

Under these circumstances, since the above-mentioned wire-wound inductance element is an open magnetic path type, it was difficult to make the shape smaller and thinner while maintaining the inductance value and Q value that indicate the characteristics. By mixing ferrite powder, which is a soft magnetic material, into a closed magnetic circuit type, the device can be made smaller and thinner, and has been put into practical use. In addition, this closed magnetic circuit type has a magnetic shielding effect, reduces leakage of magnetic flux to peripheral components, and enables high-density mounting, and is expected to develop in the future.

The ferrite powder used in this closed magnetic circuit type is fine with an average particle size of 1 to 11 μm (W Kaisho 64-129357
No., JP-A-54-163354). The reason why powder with such a fine particle size is used is thought to be that when calcined ferrite pellets are subjected to a crusher, they tend to become particles of this size, and that they are easily mixed and dispersed in the resin.

It should be noted that the mixing ratio of ferrite powder is preferably as high as possible from the viewpoint of magnetic properties, but from the viewpoint of ease of molding and mechanical strength after molding and hardening, it is currently in the range of 30 to 75% by volume. .

Problems to be Solved by the Invention As already mentioned, with the trend toward high-density surface mounting of electronic components,
As resistors and capacitors become smaller and thinner, inductance elements have become smaller and thinner by using closed magnetic circuit types, but they are still large in volume and tall, so there is a strong desire to make them smaller and thinner. .

In order to meet this demand in wire-wound inductance elements, it is necessary to improve the characteristics of the soil-molded part made of resin and ferrite powder of the closed magnetic circuit inductance element, and the present invention provides this part with high permeability. The object of the present invention is to provide an inductance element with high magnetic properties or an inductance element that is smaller and thinner than the current closed magnetic circuit type.

Means for Solving the Problems In order to solve the above problems, the inductance element of the present invention mainly contains ferrite powder mixed into the resin.
It is composed of powder having a particle size of 0 μm to 210 μm, and is molded against the soil using a resin mixed with this ferrite powder.

Further, this ferrite powder of 20 to 210 μm is mainly composed of an aggregate sintered body of fine particles of 0.5 to 10 μm.

Furthermore, the manufacturing method is to mix and knead ferrite powder mainly consisting of powder with a particle size of 20 to 210 μm with a synthetic resin, and to form an air-core coil or a coil with a magnetic core against soil using this mixed and kneaded product. The manufacturing method is such that the material solidifies accordingly.

Working ferrite powder is mainly made by crushing calcined pellets, and its magnetic properties, especially coercive force, are 0.1
While it is small, about 0a, powder is about 1000, which is about two orders of magnitude larger, and for this reason, no detailed study has been done on its use as a soft magnetic material. The present inventors investigated the relationship between the particle size of the powder and the coercive force, and found that
It was found that the coercive force decreased as the particle size increased, and powders with large particle sizes were superior to powders with small particle sizes as soft magnetic materials. The present invention has been made based on this fact. The permeability μ of a magnetic material is inversely proportional to its coercive force Ha, and the inductance L is proportional to μ of the magnetic core material, so l, Q
The relationship is CHe-'.

From the experimental results conducted based on the above, especially 20 to 21
By using powder with a particle size of 0 μm, the inductance L increases by at least 10 inches, and by 70% or more in the case of an appropriate particle size, compared to the conventional case of using powder with a particle size of about 10 μm or less.

Therefore, the size of the inductance element can be reduced by the increase in L while keeping L the same size. In other words, the height can be reduced by 10% or more, or by 70 inches or more if conditions are selected, compared to the current element.

EXAMPLES Hereinafter, the present invention will be explained in detail using experimental examples and examples.

Experimental example Fe2O3, NiO, and ZnO were A49 and 18°3, respectively.
A calcined pellet of Ni-Zn ferrite with a composition expressed as 1% and containing a small amount of additives is crushed in a crusher, and then crushed in a classifier to reduce the particle diameter to less than 5 μm,
5 μm to 10 μm, 10 μm to 20 μm.

It was divided into powders of 20 μm or more. For 2aμm1 or more, sieve 20μm~46μm, 451tm~
105μm, 105μm~150μm, 150μm~2
It was divided into powders of 10 μm, 210 μm to 300 μm, and 1300 μm or more.

These classified powders were hardened into a rod shape by adding a small amount of binder, and the coercive force H was measured using a vibrating sample magnetometer (VSM).
a was measured. The applied magnetic field is 6o○ considering the demagnetizing field.
Oe. The measurement results are shown in Figure 3. The coercive force is extremely low for small particle sizes, as high as 1,400 for particles less than 5 μm, and decreases as the particle size increases, especially for particles larger than 20 μm.
It was around oe, and even if the particle size was increased further, the decrease in Ha was small.

From this result, it can be seen that the ferrite powder currently mixed in the molding resin of the inductance element has a diameter of approximately 1 to 10 μm.
It became clear that a was as large as 10 to 140e. If the particle size of this powder is increased, for example to 20 μm or more, the HC can be lowered to about 4 to 50 e.
Inductance L can be increased.

When the state of these powders was observed with a scanning electron microscope, as shown in Figure 4 a and b, most of the powders with a size of 1 μm or less were single clean recrystallized particles, but some with a size of 20 μm
Powder with a large particle size of m or more is mainly 0.5 to 10μ
It was an aggregate sintered body of fine particles of m. Especially fine particles are 2-3
Particles with a size of μm account for the majority, and this seems to be consistent with the fact that the Hc of powder with a particle size of 20 μm or more does not decrease significantly even though the particle size increases. It seems to me. That is, the powder recrystallizes and grows to about 10 μm particles by calcination. Powder larger than this is an aggregate of recrystallized particles, each of which is partially or mostly stuck together and sintered. The size of the powder as an aggregate sintered body can be made into any size by pulverization, and if pulverization is carried out sufficiently, it can be reduced to the size of the currently used ferrite powder, i.e. 1
It is expected that it will be relatively easy to form powders of ~10 μm.

From my experience with sintered bodies up to this point, I have found that in sintered bodies, the coercive force is determined by the size of the crystal grains, that is, the size of the recrystallized particles in this trowel, but in the case of powder, According to the results of this experiment, the coercive force can be lowered by forming a sintered body of recrystallized particles.
If the size is 20 μm or more, the coercive force decreases, but even if the grain size of the aggregate sintered body is made thicker, there is no large decrease, and the decrease is only a slight one, which constitutes the aggregate sintered body. This seems to be due to the size of recrystallized particles.

From the above results, it was predicted that using larger powders among these powders would improve the characteristics of the inductance element, so as shown in Figure 1, 6% by weight of epoxy resin was mixed with these powders. After kneading the mixture, an air core coil 5 was formed against the soil, and its characteristics were measured by Qe measurement. The air-core coil 5 used was an insulation support copper wire with a copper wire diameter of 30 μm wound in 80 turns with an inner diameter of 0.8 mm and a height of 0.6 mm, and the outer diameter was approximately 1.4 mm. This air core coil 5 with terminals 6 connected to both ends is placed in a mold, filled with a mixture of ferrite powder and epoxy resin 7, molded and solidified to have a length of 3.2 mm and a width of 2.5 m.
The inductance element was finished with a size of 2.2 mm and a height of 2.2 mm. The measurement results are shown in 2N. Inductance L
Since it is approximately constant in the 0.1 to 10 M) h band, it is represented by the value of the IM ratio and expressed as the ratio to the value Lo of the air-core coil. As is clear from FIG. 2, L/Lo is 3.8 or less for the current powder of 10 μm or less, whereas a clear improvement is observed for particle sizes of 20/jm to 210 μm.

Especially for powders with a particle size of 106 μm to 160 μm, L/IJ
.

reaches 6.6, which is an improvement of 73 inches compared to 10 μm or less. 210I The reason why L/L o suddenly decreases when it is 1 m or more is because the inner diameter of the air core coil 5 is as small as 0.8 mm, so if the shape of the powder becomes too narrow, the inside of the air core coil will become boring and the filling rate will decrease. This is thought to be due to a decrease in Q is maximum at 2.6 to 3 MH, and the value Qmax is shown in Figure 2, but as an inductance element, any value of 40 or more is acceptable for use, especially 2.
In the range of 0 μm to 210 μm, the value reached approximately 60, which was good.

From the above, the particle size of the ferrite powder is 20 μm to 210 μm.
It has become clear that the characteristics of the inductance element can be improved by increasing L by 18% to 73%.

The above is a representative example of an experiment conducted using Ni-Zn ferrite, but the particle size was the same in experiments conducted with Kan-Zn ferrite, N1-Gu-Zn ferrite, and Mg-Cu-Zn ferrite. We obtained the trend results.

In addition, when we examined the distribution of the powder classified using a classifier or sieve using a particle size distribution meter, we found that there was a large amount of particles with approximately small diameters, and that particles smaller than the particle size limit were mixed in. The amount was 2 to S wt %, and a small amount of large particles were also mixed in. It is thought that some of the particles with a small particle size were adsorbed to the large powder and were mixed during classification, and some of the powder with a large particle size was separated during the treatment after classification. In any case, even if a large amount of powder is mixed in outside the limit, it will not affect the majority of people.

Further, instead of the above-mentioned air-core coil 5, a drum core wound with wire may be used as the coil.

Next, examples will be shown.

[Example 1] Ni-Zn based calcined pellet T” was lightly crushed to 1 μm.
A powder with a particle size of ˜10 μm and a powder with a particle size of 45 μm˜10 5/1 m was obtained. These powders are mixed with an epoxy resin base resin, a curing agent, a curing accelerator, a mold release agent, etc. so that the ferrite powder becomes 78 wt%, and the mixture is thoroughly mixed, kneaded with heated rolls, and rapidly cooled. Shattered. This powder was made into tablets with a diameter of smm and a length of 10mm using a molding machine. Next, prepare a plurality of coils by winding 50 turns of insulated copper wire K1-50 with a diameter of 30 μm around a Ni-Zn based sintered drum core, and glue the ends of the coils to terminals. After the temperature was raised to 170°C, the epoxy resin tablet 4 containing ferrite powder was encapsulated using a transfer molding machine, and then 10°C.
Solidified at 0℃, length: 3.2 mm, width: 1.6 mm, height: 1. An In+m inductance element was created.

As a result of measuring L and Qe of these inductance elements with an LCR meter, the particle size of the ferrite powder was 45 μm ~
In the case of 105 μm, the inductance L of 1 Ml-1,
is 68 μH, and 1 μm to 10 μm was created for comparison.
The effect of increasing the particle size of the ferrite powder was 52 μH larger than the 38 μH in the case of the powder. Regarding the Q value, both showed the highest value at 2.6MHz, and the value Qma
x is 55 from 457zm to 105μm, and from 1μm to 1
This was slightly improved from 51 in the case of 0 μm.

[Example 2] Mn = Zn-based calcined veresol - lightly crushed to 20μ
Powders with a particle size of m to 105 μm and a particle size of 1 μm to 10 μm were obtained. These powders were blended with ferrite powder at a mixing ratio of 85 wt% in the same manner as in Example 1, mixed and kneaded with an epoxy resin, rapidly cooled, and ground into powder. Next, an insulation support copper wire with a copper wire diameter of 30 μm is wound in 28 turns with an inner diameter o, emm, height o, 2 mm to form an air-core coil, and the ends of the air-core coil are glued to the terminals. Created. The - part is installed at the bottom of a mold with a hole of 3.2 mm in width and 1.6 mm in height, and 1 μm to 10 μm in height is filled with epoxy resin powder mixed with ferrite powder.
It was compression molded to 1 mm. For the other molds, epoxy resin powder mixed with ferrite powder of 20 μm to 105 μm was charged and compression molded to a height of 0.6 mm using the same mold. After being removed from the mold, both types were solidified at 160°C for 6 hours. Thereafter, the terminal portions were bent and molded to form inductance elements, and the inductance value and Q value were measured using an LCR meter. Height is 1.1m
The L of the 1 MI-Iz element was 1.8 .mu.H, but the L of the 0.6 mm inductance element, whose height was almost halved, was 1.9 .mu.H.

The Q value for both types is the highest at 2.0M)h, and the value Q
The max is 38 for 1.1mm element and 41 for 0.6mm element.
Met. By using an air-core coil without a magnetic core, the height of the element can be lowered, and when sealing the inside and outside of the coil with epoxy resin mixed with ferrite powder, it is possible to use ferrite powder with a larger particle size than before. By using this, it was possible to obtain an inductance value equivalent to that of a taller element.

[Example 3] A Ni-Cu-Zn based calcined pellet was lightly ground to a size of 1 μm to 10 J! 1m powder and 45μm ~2
A powder of 10 μm was obtained. When a portion of each was observed using a scanning electron microscope, it was found that most of the 1 μm to 10 μm powder was a single particle that had been recrystallized.
The powder of 45 μm to 21011 m was in the form of recrystallized particles of 1 μm to 10 μm gathered and partially sintered and stuck together. Each of the powders was blended with a ferrite powder mixture ratio of 172 wt% in the same manner as in Example 1, mixed and kneaded with an epoxy resin, rapidly cooled, pulverized, and then molded into a tablet with a diameter of 8 ff 1 m and a length of 10 m using a molding machine. Next, a plurality of drum cores made of a Ni--Zn based sintered body were wound with 40 turns of insulation support copper wire having a diameter of 30 μm, and the ends of the copper wires were bonded to terminals. These were placed in a mold, placed in a transfer molding machine, heated to 170°C, sealed with the aforementioned epoxy resin tablet containing ferrite powder, removed from the mold, and heated to 160°C.
It was solidified for 6 hours. Then bend the terminal part to length 3.
An inductance element having a size of 2 mm, a width of 1.6 mm, and a height of 1.1 mm was prepared, and the inductance value and Q value were measured using an LCR meter.

As a result, in an element using 1 μm to 10 μm powder, 1
The L in M1 was 25μH, but it was 45μm to 210μH.
In the powder of m, the improvement was 60% at 40 μH. Q value is 3
．． The highest value is shown at 0M-, and the value Qmax is 1 μm to 1
For 0 μm powder, it was 53.45 μm to 68 for 210 μm powder.

Experimental examples and examples using epoxy resins have been shown above, but in addition to synthetic resins, unsaturated polyester resins can also be used as thermosetting resins.

Phenol resin, etc. Also, thermoplastic resin such as nylon,
Needless to say, pps, liquid crystal polymer, etc. can be used.

Regarding the mixing rate of ferrite powder, since the powder particle size of the present invention is large, the surface area of the powder is small, and if the same thickness of resin is attached to the powder surface, the amount of resin will be smaller. Only by increasing the ratio of ferrite powder in the molding resin. In the experimental example, the mixing rate of ferrite powder was 96% by weight, which was calculated using specific gravity to be 82 volumetric units, which exceeds the current upper limit of 76 volumetric units. In order to improve the magnetic properties, it is preferable to increase the mixing rate of ferrite powder as much as possible, and the present invention is in accordance with this direction, and the mixing rate can be further increased by improving the strength of the resin itself and reforming the sealing molding method. there is a possibility.

Effects of the Invention As described above, in a wire-wound inductance element, in a closed magnetic circuit element in which an air-core coil or a five-core coil is sealed and molded with a synthetic resin mixed with ferrite powder, the ferrite powder is mixed with a particle size of 20 μm to 210 μm + 7). Compared to using conventional ferrite powder,
The inductance Li can be improved by 10% or more, and by 70% or more if conditions are selected. Also, the inductance Li
If they are the same, the size of the element, especially the height, should be reduced by 10%.
As described above, if the conditions are selected, the size can be reduced by 70% or more. INDUSTRIAL APPLICABILITY The present invention has high industrial value as it provides a surface-mount inductance element that is desired to have higher performance, be thinner, and be lighter.

[Brief explanation of the drawing]

FIG. 1 is a cross-sectional view showing an embodiment of the inductance element of the present invention, and FIG. 2 is an inductance element sealed and molded with resin containing ferrite powder. Figure 3 is a diagram showing the relationship between the ratio L/Lo and the maximum Q value Qmax and the particle size of ferrite powder, Figure 3 is a diagram showing the relationship between the coercive force and particle size of ferrite powder, Figure 4a, b is a scanning electron micrograph of ferrite powder, and FIG. 5 is a schematic diagram showing a typical structure of a conventional inductance element. 6... Coil, 6... Terminal, 7...
···resin. Name of agent: Patent attorney Toshio Nakao and one other person W&
1 Figure 21 JA Shiki A Akira C2 Rim) Figure 3! L degree (Doji Figure 4 (D-near 12., jl, f)" - J + = (bottom, δt, large surface, 扬・?7L hoe, meko K, smoke Figure 5 procedural amendment form Working Ceremony) October 13D, 1986

Claims (3)

[Claims] (1) An inductance element in which an air-core coil or a magnetic core-containing coil is sealed and molded with a synthetic resin containing ferrite powder, and the particle size of the ferrite powder is mainly 20 to 210 μm. (2) The inductance element according to claim 1, wherein the ferrite powder is mainly composed of a sintered aggregate of particles having a particle size of 0.5 to 10 μm. (3) Mix and knead ferrite powder mainly consisting of powder with a particle size of 20 to 210 μm with a synthetic resin, seal and mold an air-core coil or magnetic core-containing coil with this mixed and kneaded product, and solidify as necessary. A method of manufacturing an inductance element, characterized in that: