JPH0472602A - Manufacture of magnetic paint, conductive paint, green laminated body and laminated inductor - Google Patents

Abstract

PURPOSE:To augment the filling up density of a painted film by a method wherein, within a magnetic paint containing an organic coupling agent, as for the organic coupling agent, a polyether polyurethane resin having a specific radical and at the transition temperature of a glass in specific value is used. CONSTITUTION:As for the laminated inductor, a magnetic paint containing mild magnetic ferrite fine powder and an organic coupling agent as the main component and an organic solvent as a scattering medium is used. At this time, as for the organic coupling agent, a polyether polyurethane resin having- COOM(M represents at least one kind out of H,K,Na) and at the glass transition temperature not exceeding 60 deg.C is used. Through these procedures, the excellent powder scattering characteristics can be exhibited resultantly the filling up density of a painted film can be augmented.

Description

Detailed Description of the Invention [Industrial Application Field] The present invention relates to a multilayer inductor such as a surface mount inductor element or an impedance element obtained by laminating and sintering a magnetic layer and a conductor layer for a coil. .

[Conventional technology] In recent years, electronic devices have become rapidly smaller and lighter.

The electronic circuits and electronic components that make up these devices are becoming smaller and smaller, and inductors such as inductors and impedance elements, which play an important role in circuit construction, are chip-type with a laminated structure that can be surface mounted. elements are becoming mainstream.

A multilayer inductor used to be mounted on a printed circuit board, etc. usually has a magnetic layer made of soft magnetic ferrite fine powder and a binder, and a conductor layer made of conductive fine powder and a binder, which are alternately laminated. After.

It is formed by sintering.

Therefore, the factors that affect the performance of such multilayer inductors include not only the characteristics of the main raw material, ferrite fine powder or conductive fine powder itself, but also the binder, which is essential for forming the coating film of these fine powders. These characteristics are cited as extremely important.

That is, the main properties required of a binder are:

It must be able to provide sufficient mechanical strength and flexibility to support the manufacturing process, it must be able to provide compressibility during lamination, and the debonding agent treatment performed as a pre-sintering treatment must be at a low temperature. It can be mentioned that it can be done completely and completely.

Binders that meet these requirements include nitrocellulose, ethylcellulose, and polyvinyl butyral in non-aqueous systems, that is, systems using organic solvents as a dispersion medium, and various plasticizers are used in combination to impart flexibility. It has been widely used in the form of

[Problems to be Solved by the Invention] However, in promoting further miniaturization and higher performance, it has become clear that these conventional binders have various drawbacks.

That is, in order to achieve further miniaturization while ensuring the same performance, it is necessary to improve the powder filling rate of the magnetic layer and conductor layer, but the conventional binder is The dispersion properties of conductive powders such as silver-palladium mixed powders are poor, and therefore a high powder filling rate cannot be expected.

Secondly, the above-mentioned binders generally have a high glass transition temperature and therefore have poor flexibility, so it is essential to add a plasticizer. Therefore,! ! ! ! In aiming to improve the filling rate of the membrane, the question is how to reduce the amount added.

Therefore, the technical problem of the present invention is to solve the drawbacks of conventional binders and to create a magnetic paint and conductive paint that are mainly used for small, high-performance laminated inductors, and a green paint for laminated inductors using the same. An object of the present invention is to provide a laminate and a method for manufacturing a laminate inductor.

[Means to solve the problem]

According to the present invention, in a magnetic paint containing soft magnetic ferrite fine powder and an organic binder as main components and an organic solvent as a dispersion medium, the organic binder is -COOM (M is H
, K, , has at least one type of shk group in Na,
In addition, a magnetic coating material characterized by being a polyether polyurethane resin having a glass transition temperature of 60° C. or less can be obtained.

According to the present invention, in a conductive paint containing a metal derivative powder and an organic binder as main components and an organic solvent as a dispersion medium, the organic binder has -COOM (M
A conductive paint is obtained, which is a polyether polyurethane resin having at least one group selected from H, K, and Na) and having a glass transition temperature of 60° C. or lower.

According to the present invention, a plurality of magnetic layers containing soft magnetic ferrite fine powder and an organic binder as main components.

A green laminate comprising conductor layers containing fine metal powder and an organic binder as main components.

The organic binder in at least one of the magnetic layer and the conductive layer has -COOM (M is H, K) as a side chain.

A green laminate is obtained, which is characterized by being a polyether polyurethane resin having at least one type of Na) group and having a glass transition temperature of 60° C. or less.

According to the present invention, a ferrite paint containing a soft magnetic ferrite fine powder and an organic binder as main components, a ferrite paint containing an organic solvent as a dispersion medium, and a ferrite paint containing a metal fine powder and an organic binder;
A method for producing a multilayer inductor, in which a conductive paint containing an organic solvent as a dispersion medium is alternately printed, dried after each printing operation to form a green laminate, and sintered. The organic binder contained in at least one of the conductor layers has a side chain of -COOM (M is H, K).

A method for manufacturing a multilayer inductor is obtained, which is characterized in that the polyether polyurethane resin has at least one type of Na (Na) group and has a glass transition temperature of 60° C. or lower.

Here, the polyether polyurethane resin that can be used in the present invention is a polyether polyurethane having an ether bonding site in the main chain, and as a side chain -
Any polyether polyurethane resin may be used as long as it has a COOM group (M is at least one of H and KNa) and has a glass transition temperature of 60° C. or less. This is because if the glass transition temperature of the polyether polyurethane resin exceeds 60° C., the two effects of the present invention, imparting flexibility, cannot be achieved without the addition of a plasticizer, which is not preferable. Moreover, -CO of the polyether polyurethane resin
The concentration of the OM (M is at least one of H, K, and Na) groups is preferably in the range of 0.01 to 0.95 mmol/g. I mean.

If the concentration of this -C00M group is 0.01 mmol/g or less, the improvement in the packing density of the powder, which is one effect of the present invention, cannot be expected, and if this concentration is 0.95 m*ol/g
This is because the above is undesirable because it may cause gelation of the paint.

[Function] As the organic binder in the present invention, -COOM (M is H
, K, or Na) group-containing polyether polyurethane resin as follows.

That is, the -COOM (M is at least one of H, K, and Na) group introduced as a side chain.

In order to produce a conductive fine powder surface represented by ferrite fine powder and silver-palladium having a hydrophilic surface,
Excellent powder dispersion properties are obtained, resulting in improved coating density.

Second, since the glass transition temperature is 60° C. or lower, the resin itself has a sufficient degree of flexibility for practical use.

Therefore, appropriate flexibility and compressibility can be obtained without the addition of plasticizers, and plasticizers, which are a factor in reducing coating film density, can be eliminated.

As a result, the packing density of the coating film is improved.

Third, since the main chain has an ether bonding site, this site is easily subjected to oxidative decomposition at relatively low temperatures, and as a result, the debinding agent treatment proceeds rapidly.

These effects improve the powder packing density of the magnetic coating film and conductive coating film, which are essential for downsizing multilayer inductors, and provide excellent processability.

[Example] An example of the present invention will be described below with reference to the drawings.

An example of a multilayer inductor according to the present invention.

A detailed explanation will be given below with reference to the drawings.

Figure 1 shows the basic configuration of a multilayer inductor. 1 Although it is originally configured in a connected state, for the sake of simplicity, it is shown as a configuration diagram of unit components and a part of the conductor is emphasized. are doing.

In FIG. 1, a green laminate 10 is formed by repeatedly printing and drying a magnetic layer 11 made of ferrite and a conductor layer 12 sequentially and alternately from the bottom layer.

The conductor layer 12 formed on the inner surface of the magnetic layer 11 is made of a conductor paint whose main components are fine metal powder and an organic binder.

The green laminate shown in FIG. 1 was integrally sintered.

A sintered body 20 shown in FIG. 2 is obtained. This sintered body 20 has film-like electrode terminals 31A, 31 on the end surface as shown in FIG.
B is provided to complete the multilayer inductor 30.

Here, a specific manufacturing example of the inductor of the present invention will be explained. Ferrite paints and conductor paints with different compositions were created, and the various properties of each paint film were evaluated before and after the binder removal treatment, and the laminated inductors of Examples 1 and 2 were prototyped using these paints. . In addition, samples of Comparative Examples 1 to 4 were prepared for comparison.

Example 1 The ferrite paint composition shown in Table 1 was made into a paint using a pressure kneader and a sand grinder, and a film was formed using a doctor blade method so that the thickness after drying would be 70 μm, and the gloss was measured using a gloss meter. After conducting a flexibility test using a bending test, binder removal treatment was performed and the binder removal completion temperature was determined using a thermobalance method.

Example 2 The conductive paint composition shown in Table 2 was made into a paint using a pressure kneader and a sand grinder, and an electrode pattern of 0.3 w x 2 am was formed using a silk screen printing method so that the thickness after drying was 10 μm. A film was formed and the pattern accuracy was observed using a microscope. Furthermore, using the same paint, a film was formed using the doctor blade method to a thickness of 10 μm after drying, and the gloss was measured using a gloss meter and the flexibility was tested using a bending test.

The binder removal process was performed, and the temperature at which the binder removal was completed was determined by a thermobalance method.

Comparative Example 1 A ferrite coating film was prepared and evaluated in the same manner as in Implementation Project 1, except that the ferrite coating composition in Example 1 was changed to the composition shown in Table 3.

Comparative Example 2 A ferrite coating film was prepared and evaluated in the same manner as in Example 1, except that the ferrite coating composition in Example 1 was changed to the composition shown in Table 4.

Comparative Example 3 A conductive coating film was prepared and evaluated in the same manner as in Example 2, except that the conductive coating composition in Example 2 was changed to the composition shown in Table 5.

Comparative Example 4 A conductive coating film was prepared and evaluated in the same manner as in Example 2, except that the conductive coating composition in Example 2 was replaced with the composition shown in Table 6.

Examples 1 to 2 above. Table 7 shows the evaluation results of each coating film obtained in Comparative Examples 1 to 4.

In Table 7, glossiness is an index of the degree of dispersibility of ferrite powder or conductor powder.

It can be said that the larger the value, the better the dispersion state.

In a multilayer inductor, it is extremely meaningful to improve the dispersibility of ferrite powder or conductor powder. That is, in the magnetic layer.

It is possible to improve the ferrite powder filling rate, and in the conductor layer, it is possible to improve the conductive powder filling rate, and the uniformity of the mixed powder is promoted, which improves reliability under high temperature and high humidity conditions. As a result, the occurrence of conductor damage, disconnection, etc. can be sufficiently suppressed.

Also, in Table 7, it is a measure of the flexibility of a magnetic layer or conductor layer containing ferrite and having elasticity. If the flexibility of the magnetic layer or conductor layer is insufficient, 1
This is undesirable because cracks may occur during sheet formation, or poor compression may occur when the sheet is multilayered, resulting in decreased workability or product defects.

Further, the binder removal completion temperature in Table 7 is preferably as low as possible in order to prevent delamination due to volumetric expansion or contraction caused by the oxidation-reduction phenomenon of the conductor powder that occurs during sintering of the conductor.

Needless to say, the lower the DC resistance value of the conductor layer in Table 7 is, the more preferable it is, and as an effect of reducing the DC resistance value, improved reliability and thinning of the conductor layer can be expected.

The pattern accuracy in Table 7 is a measure of the shape flexibility, thinning, and miniaturization of the conductor layer, and is an essential element for miniaturizing and improving the performance of multilayer inductors.
This strongly depends on the dispersion state of the conductive paint. That is, as can be seen from Table 7, 9 Examples 1 to 2 of the present invention. Comparative Examples 1 to 4 are extremely effective in reducing the size and increasing reliability of multilayer inductors.

Next, a laminated inductor was prototyped using each of the paint compositions of the above examples and comparative examples, and their characteristics were compared.

Example 3゜A ferrite paint (Example 1) with the composition shown in Table 1 and a conductive paint (Example 2) with the composition shown in Table 2 were used to laminate in the basic configuration shown in Figure 3. A type inductor was prepared, and the magnetic permeability μ of the magnetic layer and the external shape when satisfying the specifications shown in Table 8 were determined. Here, the integration sintering temperature was 930°C.

Comparative Example 5 Lamination was carried out in the same manner as in Example 3, except that a ferrite paint with the composition shown in Table 5 (Comparative Example 3) and a conductive paint with the composition shown in Table 6 (Comparative Example 4) were used. A type inductor was prepared, and the magnetic permeability μ of the magnetic layer and the external shape satisfying the specifications shown in Table 8 were determined. The results are shown in Table 9.

From this table, it can be seen that the multilayer inductor of the present invention is significantly smaller in size than products of the same performance made by conventional methods.

This is due to the following two effects.

That is, first, the inductance L of the inductor element is proportional to the magnetic permeability μ of the magnetic layer and the magnetic path cross-sectional area S of this magnetic layer. Therefore, under the condition that the inductance L is constant, as the magnetic permeability μ increases, the cross-sectional area S which is the volume factor of the element
decreases.

Second, the thickness of the conductor layer is inversely proportional to the DC resistance value of the conductor layer under the condition that the conductive volume DC resistance value is constant.

Therefore, if the direct current resistance value of the conductor layer decreases, the thickness of the conductor layer, which is a volume factor of the device, decreases.

In one aspect of the present invention, the method for forming the ferrite coating film or the conductive coating film is a gravure printing method, a screen printing method, or a doctor blade method.

It should be noted that the effects of the present invention will not change in any way no matter what forming method, such as extrusion forming or injection forming, is used.

Margins [Effects of the Invention] As explained above, the present invention can provide a multilayer inductor that is small, has high performance, and has high reliability.

[Brief explanation of the drawing]

FIG. 1 is a sectional view showing the basic structure of a multilayer inductor according to an embodiment of the present invention, FIG. 2 is a perspective view showing the shape of the inductor shown in FIG. 1 after sintering, and FIG. FIG. 3 is a perspective view showing a state in which electrodes are provided on the inductor of FIG. In the figure, 10 is a green laminate and 11 is a magnetic layer. 12 is a conductor layer, 20 is a sintered body, 30 is a laminated inductor, and 31A and 31B are electrode terminals.

Claims (4)

[Claims] 1. A magnetic paint containing soft magnetic ferrite fine powder and an organic binder as main components and an organic solvent as a dispersion medium, wherein the organic binder has a -COOM (M is at least one of H, K, and Na) group. and the glass transition temperature is 60
A magnetic paint characterized by being a polyether polyurethane resin with a temperature below ℃. 2. Contains metal derivative powder and organic binder as main components,
In a conductive paint containing an organic solvent as a dispersion medium, the organic binder has -COOM (M is H, K) as a side chain.
, at least one type of Na) group, and is a polyether polyurethane resin having a glass transition temperature of 60° C. or less. 3. A green laminate comprising a plurality of magnetic layers containing a soft magnetic ferrite fine powder and an organic binder as main components, sandwiching a conductor layer containing a metal fine powder and an organic binder as the main components, the green laminate comprising: The organic binder in at least one of the magnetic layer and the conductive layer has -COOM (M is H,
1. A green laminate characterized by being a polyether polyurethane resin having at least one of K and Na) groups and having a glass transition temperature of 60° C. or less. 4. A ferrite paint containing a soft magnetic ferrite fine powder and an organic binder as the main components and an organic solvent as a dispersion medium, and a conductive paint containing a metal fine powder and an organic binder and an organic solvent as a dispersion medium are alternately layered. A method for manufacturing a multilayer inductor, in which a green laminate is formed by printing, drying after each printing operation, and sintering, wherein the organic binder contained in at least one of the magnetic layer and the conductor layer has - as a side chain. It has a COOM (M is at least one of H, K, and Na) group, and has a glass transition temperature of 6
A method for manufacturing a laminated inductor, characterized in that it is made of polyether polyurethane resin having a temperature of 0°C or less.