KR101661067B1 - Manufacturing method of metal polymer complex sheet - Google Patents

Abstract

Disclosed is a method for producing a metal polymer composite sheet in which the dispersibility of a metal polymer composite sheet is remarkably increased in a slurry for sheet production when the sheet is produced by a thick film process. The method comprises the steps of preparing a slurry in which first and second metal powders having different particle sizes are dispersed, a second metal powder having a relatively smaller particle size is first dispersed in a solvent, Preparing a slurry by tape casting and curing the slurry to form a composite sheet; mixing the slurry with a solution to form a mixture, and then dispersing a first metal powder having a relatively larger particle size in the mixture to produce the slurry; . The first metal powder may be at least one selected from the group consisting of Fe-Si, Fe-Ni-Si, Fe-Cr-Si and Fe-Al- The powder may be a carbonyl iron powder (CIP) composition having a particle size of 3 to 4 탆. According to the present invention, since the viscosity of the slurry is lowered and the dispersibility of the metal solid component is drastically improved and the content of the metal solid content can be greatly increased under the same conditions, the slurry is tape-cast to produce and laminate a plurality of composite sheets When the inductor is manufactured, its magnetic characteristics can be greatly improved.

Description

TECHNICAL FIELD [0001] The present invention relates to a method for producing a metal polymer composite sheet,

The present invention relates to a method for producing a metal polymer composite sheet, and more particularly, to a method for producing a metal polymer composite sheet having increased dispersibility in a slurry for producing the composite sheet.

In recent years, a power inductor widely used for a power conversion circuit such as a power circuit or a DC-DC converter is configured as a laminated structure in which a plurality of ferrites or a plurality of low dielectric constant ceramic sheets are laminated rather than a winding-type structure in which coils are wound around a ferrite core. This is because, in the case of a wire-wound structure, the high-frequency characteristics deteriorate due to the stray capacitance between the coils.

The general structure of such a stacked type power inductor can be schematically shown in Fig. That is, the power inductor 1 is formed by stacking a plurality of ceramic sheets as dummies to form the main body 10. On the ceramic sheets, a metal electrode pattern is printed to form the internal electrodes 16 of the inductor 1. [ The internal electrodes 16 are connected to each other by conductive vias (not shown) formed on the respective ceramic sheets. Finally, the external electrodes 20 attached to the surface of the main body 10 for inputting and outputting the electric signals, Lt; / RTI >

As the composition of the ceramic sheet, ferrite, a metal material and the like can be mentioned. However, ferrite has a low saturation magnetization value and poor current characteristics, and a metal material has a problem of large eddy current and hysteresis loss at a high frequency band.

Accordingly, in recent years, ceramic sheets for inductors are produced as a composite sheet composed of a composition in which metallic powder is mixed with glass or resin to maintain insulation between metal powder particles. The metal powder thus coated with the insulating layer is generally mixed with an epoxy resin as a binder to form a composite sheet.

For example, Japanese Patent No. 4881192 (published on Mar. 22, 2012) discloses a method of manufacturing electronic components, in which Bi ₂ O ₃ is coated on Fe-Cr-Si-based metal magnetic alloy powder particles, Disclosed is a technique for preventing an insulation failure due to heat or a defective breakdown voltage.

Particularly, recently, inductors are required to have a large current of rated current, so that one or two kinds of soft magnetic metal powders having different particle sizes are mixed to improve magnetic properties such as magnetic permeability and inductance and to increase the filling rate of metal powder A composite sheet is being developed.

As a related example, in the "laminated inductor" of Japanese Patent No. 5048155 (published on Oct. 17, 2012) and "laminated inductor" of Japanese Patent No. 5048156 (published on Oct. 17, Si based soft magnetic metal powder is used to produce a composite sheet.

On the other hand, in order to produce such a composite sheet, a tape casting process for forming a sheet must be performed in a state that the metal powder is well dispersed. In this process, a dispersion slurry having a high concentration should be produced while maintaining a high viscosity, and thus it is possible to produce a composite sheet containing a large amount of solid components and having excellent magnetic properties.

However, when the slurry is prepared by using the metal powder mixed with the large particles and the small particles as described above, the powder having a large particle size easily precipitates, thereby increasing the viscosity of the slurry and adversely affecting the dispersion of the metal particles , And it is impossible to disperse a higher solid content depending on conditions.

Therefore, there is a need for a manufacturing method which improves the dispersibility of the solid metal powder in the production of the composite sheet as described above.

Accordingly, the present invention provides a method for producing a metal polymer composite sheet having increased dispersibility in a slurry for producing a composite sheet.

In order to accomplish the above object, the present invention provides a method for producing a sheet of metal polymer composite, which comprises preparing a slurry in which first and second metal powders having different particle sizes are dispersed, Dispersing a second metal powder having a small particle size first in a solvent and mixing with a resin solution to form a mixture and then dispersing a first metal powder having a relatively larger particle size in the mixture to prepare the slurry; And tape casting and curing the slurry to produce the composite sheet.

At this time, the particle size of the first metal powder may be 10 to 15 탆, and the particle size of the second metal powder may be 3 to 4 탆.

The composition of the first metal powder may be at least one selected from the group consisting of Fe-Si, Fe-Ni-Si, Fe-Cr-Si and Fe- And may be carbonyl iron powder (CIP).

The first metal powder and the second metal powder may be coated with an insulating layer in order to maintain the insulating property between the respective powder particles, and the composition of the insulating layer may be Fe ₃ (PO ₄ ), Al ₃ (PO ₄ ) Bi ₂ O _3, and the like.

In addition, the content of the metal solid content dispersed in the slurry may be adjusted to 50 to 75 vol% based on the total amount of the slurry.

The content of the first metal powder and the second metal powder may be adjusted to 1: 1.

In the step of preparing the slurry, a dispersant may be added when the first metal powder and the second metal powder are dispersed. The dispersant may be at least one selected from the group consisting of BYK-111, BYK-103 and a silane coupling agent And the addition amount of the dispersant may be 0.2 to 1.5 wt% based on the total amount of the first metal powder and the second metal powder when dispersed.

The solvent may be at least one selected from the group consisting of methyl ethyl ketone (MEK), ethanol, IPA, toluene, and xylene.

The resin may be an epoxy resin, for example, a novolac epoxy resin, a phenoxy type epoxy resin, a BPA type epoxy resin, a BPF type epoxy resin, (BPF) epoxy resin, hydrogenated BPA epoxy resin, dimer acid modified epoxy resin, urethane modified epoxy resin, rubber modified epoxy resin, an epoxy resin, and a DCPD type epoxy resin.

The curing may be carried out at a temperature of 120 to 200 DEG C for 10 minutes to 1 hour.

According to the present invention, a metal powder having a relatively smaller particle size range is first dispersed in a solvent and mixed with a resin, and then the remaining metal powder is mixed with a resin, using two different metal powders having different particle size ranges, When the slurry is prepared by dispersing, the viscosity of the slurry is lowered and the dispersibility of the metal solid component is remarkably improved. Thus, the content of the metal solid content can be greatly increased under the same conditions, so that the magnetic properties of the final inductor produced by the composite sheet produced by tape casting of the slurry can be greatly improved.

1 is a cross-sectional view of a general schematic structure of a stacked type power inductor.
FIGS. 2A and 2B are electron micrographs of two kinds of metal powder particles coated with an insulating layer used as a composition of a composite sheet for an inductor in general, wherein FIG. 2A is of Fe-Si powder and FIG. 2B is carbon of iron Powder (CIP).
FIG. 3 is a schematic view illustrating a process for producing a slurry by dispersing a mixed powder obtained by mixing two metal powders at a ratio of about 1: 1 with a dispersant in a solvent.
4A to 4E are photographs showing dispersions in the slurry prepared according to the process of FIG. 3, wherein the content of each metal solid content is 50 vol% in FIG. 4A, 55 vol% in FIG. 4B, 60 vol% 4d is 65 vol%, and Fig. 4e is 70 vol%.
5 is a schematic diagram illustrating a process in which the remaining metal powder is dispersed after the metal powder having a relatively smaller particle size range is first dispersed in the solvent and mixed with the resin according to the present invention.
6A to 6E are dispersion results of the embodiment according to the process of the present invention shown in FIG. 5, wherein the final metal solid content in the prepared slurry is 50 vol% in FIG. 6A, 55 vol% in FIG. 6B, 60vol%, Figure 6d is 65vol%, and Figure 6e is 70vol%.
Fig. 7 is a graph showing the final solid metal content in slurries prepared using Fe-Si powders having particle sizes of 10-15 [mu] m and carbonyl iron powder (CIP) 3-4 [mu] m, 5 is a graph showing the viscosity of the slurry prepared according to the process of FIG. 5 according to the content of the dispersant.
FIG. 8 is an electron micrograph of a cross section of a composite sheet produced by tape-casting and then curing the slurry of FIG. 6E containing 70 vol% of metal solids in accordance with the process of the present invention shown in FIG.
BRIEF DESCRIPTION OF THE DRAWINGS The invention will be described in detail with reference to the accompanying drawings.

As described above, when a mixed powder obtained by mixing metallic powders having different particle size ranges in a general slurry manufacturing process for producing a composite sheet for inductor is dispersed in a solvent, the viscosity of the slurry is increased, Which in turn significantly degrades the magnetic properties of the inductor being fabricated.

2A and 2B are electron micrographs of two kinds of metal powder particles coated with an insulating layer prepared by mixing as a composition of the composite sheet for inductor, wherein FIG. 2A is of Fe-Si powder and FIG. 2B is carbon of iron Powder (CIP: Carbonyl Iron Powder). The insulating layer is Fe ₃ (PO ₄ ) and / or Al ₃ (PO ₄ ) composition.

In the case of this Fe-Si powder, the particle size is approximately 10 to 15 μm and the density is 7.78 g / cm 3. In the case of carbonyl iron powder, the particle size is approximately 3 to 4 μm and the density is 7.35 g / cm 3. Therefore, in these metal powders, the main component is iron (Fe), which is very dense, and particularly in the case of Fe-Si powder, precipitation easily occurs. Therefore, when the slurry for producing a composite sheet is prepared by mixing these metal powders, The dispersion efficiency of the powder naturally deteriorates.

Fig. 3 is a schematic view for explaining a process for producing a slurry by mixing and dispersing Fe-Si powder and carbonyl iron powder (CIP) as two types of metal powders having different particle sizes.

4A to 4E illustrate that after mixing the two metal powders in a ratio of about 1: 1 (by vol% or wt%) according to the manufacturing process of FIG. 3, the mixed powder is mixed with a small amount of a commercial dispersing agent in a solvent Methyl ethyl ketone (MEK) solution to prepare a slurry. The content of the metal solid in the slurry is 50 vol%, 4 vol%, 60 vol%, 4 vol%, and 70 vol%, respectively.

4A to 4E, it can be seen that the dispersion state of the mixed powder is significantly different according to the volume ratio of the metal powder to the total amount. It can be seen that the dispersed slurry can not be obtained when the metal solid content is up to 60 vol%, but when it is from 65 to 70 vol%.

Further, it is confirmed that the powder particles are uniformly and well dispersed in the solvent as the slurry is well formed and the viscosity is low. The lower the viscosity under the same conditions, the better the process convenience as well as the advantage of good dispersion characteristics since the composite sheet can be produced as a condition containing a larger amount of solids in the actual process.

According to this observation, the present invention provides a slurry for a composite sheet of a metal-resin by dispersing two magnetic metal powders, which are different kinds of solid particles having different particle size ranges, in a resin solution, The present inventors propose a manufacturing method that dramatically improves the dispersibility of a solid metal powder by using scientific facts that are difficult to disperse as the particle size becomes smaller and disperse more easily as the particle size becomes larger. As the content of the metal solid increases due to the increased dispersibility, the magnetic properties of the finally produced inductor can be greatly improved.

That is, according to the present invention, two metal powders having different particle size ranges are used, and instead of being mixed and dispersed in a solvent simultaneously, the two metal powders are separately dispersed in a solvent in a separate process. Specifically, in the present invention, after the metal powder having a relatively smaller particle size range is first dispersed in the solvent and mixed with the resin, the remaining metal powder is dispersed later. 5 is a schematic diagram for explaining this.

3 and 4A to 4E, the metal powder having a small particle size dispersed first has a solid fraction ratio with respect to the amount of the solvent as compared with the case of dispersing the mixed powder in which the two metal powders having different particle size ranges are first dispersed The dispersion is reduced by half (1/2), which makes dispersion very favorable.

Moreover, metal powders of large particle size are relatively easier to disperse in nature, but additionally, because the metal powders having a smaller particle size range as described above are first dispersed in the solvent and dispersed after mixing with the resin, Since the amount of the solvent relative to the metal powder having a large particle size of the solvent and the resin is relatively increased, the ease of dispersion is remarkably increased.

According to the present invention, the particle sizes of the two kinds of metal powders having different particle size ranges can be in the range of 10 to 15 μm and in the range of 3 to 4 μm, respectively. The metal powder having a particle size in the range of 10 to 15 占 퐉 may have a composition of at least one of Fe-Si, Fe-Ni-Si, Fe-Cr-Si and Fe-Al- Do. In addition, the metal powder having a particle size in the range of 3 to 4 mu m can be carbonyl iron powder (CIP). The final dispersed metal solid content in the prepared slurry is preferably 50 to 75 vol% based on the total amount. In addition, the two kinds of metal powders may be coated with an insulating layer selected from one or more of Fe ₃ (PO ₄ ), Al ₃ (PO ₄ ) and Bi ₂ O ₃ compositions so that the intergranular insulation can be maintained. The content of each of the two metal powders may be about 1: 1 (based on vol% or wt%).

Further, according to the present invention, a small amount of dispersant can be added when the metal powder is dispersed. One or more of the dispersing agents BYK-111, BYK-103 and silane coupling agents may be used as the dispersing agent, and the content thereof is such that the total amount of the metal powder dispersed (that is, the metal powder of smaller particle size is dispersed in the solvent , And the total amount of metal powder of the larger particle size thereafter when the metal powder is added and dispersed) is preferably 0.2 to 1.5 wt%.

According to the present invention, methyl ethyl ketone (MEK), ethanol, IPA, toluene or xylene can be used as the solvent, but methyl ethyl ketone (MEK) is preferable.

According to the present invention, the resin may be an epoxy resin, for example, a novolac epoxy resin, a phenoxy type epoxy resin, a BPA type epoxy resin ), BPF type epoxy resin, hydrogenated BPA epoxy resin, dimer acid modified epoxy resin, urethane modified epoxy resin, rubber modified epoxy resin, A rubber modified epoxy resin, and a DCPD type epoxy resin.

Further, according to the present invention, the slurry produced as described above is subjected to tape casting and then the epoxy resin contained therein is cured to produce a composite sheet. Such curing can be achieved in the temperature range of approximately 120 to 200 DEG C in the range of 10 minutes to 1 hour. Also, as described above in connection with FIG. 1, such composite sheets may be made in plurality and laminated as a stack to ultimately form the body 10 of the inductor, for example.

6A to 6E are dispersion results of the embodiment according to the process of the present invention shown in Fig. 5, wherein the final metal solid content in the prepared slurry is 50 vol% in Fig. 6A, 55 vol% in Fig. 6B, 60vol%, Figure 6d is 65vol%, and Figure 6e is 70vol%. Specifically, carbonyl iron powder (CIP) having a particle size of 3 to 4 占 퐉 was dispersed in solvent MEK at 300 rpm for 1 hour together with 0.4 to 0.8 wt% of BYK-111 based on the total amount, After mixing with the resin, Fe-Si powders having a particle size of 10 to 15 mu m were mixed and dispersed at 200 rpm for 2 hours. At this time, the contents of carbonyl iron powder (CIP) and Fe-Si powder were set to approximately 1: 1.

6a to 6e show the dispersed state according to the change in the content of the final metal solid in the prepared slurry, and particularly FIG. 6e showing the maximum content of the solid metal content. Even when the solid content is increased to 70 vol% It can be confirmed that it is mixed. This is a marked improvement over the very inferior dispersion (see FIG. 4e) of the slurry having a solids content of 70 vol% when made according to the process of FIG.

7 is a graph showing the final solid metal content of 60 vol% in a slurry prepared using Fe-Si powder having a particle size of 10 to 15 占 퐉 and carbonyl iron powder (CIP) having 3 to 4 占 퐉, 3 and the slurry prepared according to the process of FIG. 5, and comparing the viscosity according to the dispersant amounts. The remaining composition and process conditions are the same as those of Figs. 4C and 6C except for the dispersant content varying in the process of Figs. 3 and 5, respectively.

Referring to FIG. 7, the viscosity tends to decrease as the content of the dispersant increases. In particular, in the case of the slurry according to the process of FIG. 5, that is, the process according to the present invention, it is observed that the viscosity is excellent and the viscosity is extremely low, ie, less than half. Thus, it can be seen that according to the process of Fig. 5, i.e. the process according to the invention, a viscosity capable of producing a composite sheet containing up to about 70 vol% of metal solids content can be obtained.

8 is a cross-sectional view of a composite sheet prepared by tape-casting the slurry of FIG. 6E containing 70 vol% of metal solid content and curing an epoxy resin contained therein according to the process of the present invention shown in FIG. 5, ion beam). FIG.

8, it is observed that a metal powder of a large particle, a metal powder of a small particle and an epoxy resin form a composite sheet which is relatively uniformly mixed.

The various characteristics of the preferred embodiments of the present invention described above may vary somewhat within a conventional error range depending on the powder characteristics such as the average particle size, distribution and specific surface area of the composition powder, and the purity of the raw material, Is quite natural for those of ordinary skill in the art.

It will be apparent to those skilled in the art that various modifications and variations can be made in the present invention without departing from the spirit and scope of the invention as defined by the appended claims. , Additions and the like are to be regarded as belonging to the claims.

Claims (17)

A method for producing a composite sheet comprising a metal and a polymer,
A second metal powder having a relatively smaller particle size is first dispersed in a solvent and mixed with a resin solution to prepare a slurry in which a first metal powder and a second metal powder having different particle sizes are dispersed, Dispersing a first metal powder having a relatively larger particle size in the mixture to form the slurry after forming the mixture;
And casting and curing the slurry to produce the composite sheet. ≪ RTI ID = 0.0 > 21. < / RTI > The method according to claim 1,
Wherein the first metal powder has a particle size of 10 to 15 占 퐉. The method according to claim 1,
Wherein the second metal powder has a particle size of 3 to 4 占 퐉. The method according to claim 1,
Wherein the composition of the first metal powder is at least one selected from the group consisting of Fe-Si, Fe-Ni-Si, Fe-Cr-Si, and Fe-Al-Si. The method according to claim 1,
Wherein the composition of the second metal powder is carbonyl iron powder (CIP). The method according to claim 1,
Wherein the first metal powder and the second metal powder are coated with an insulating layer. The method according to claim 6,
Wherein the composition of the insulating layer is at least one selected from the group consisting of Fe ₃ (PO ₄ ), Al ₃ (PO ₄ ), and Bi ₂ O ₃ . The method according to claim 1,
Wherein the content of the metal solid dispersed in the slurry is 50 to 75 vol% based on the total amount of the slurry. The method according to claim 1,
Wherein the content of the first metal powder and the second metal powder is 1: 1. The method according to claim 1,
Wherein the dispersing agent is added when the first metal powder and the second metal powder are dispersed in the step of preparing the slurry. 11. The method of claim 10,
Wherein the dispersant is at least one selected from the group consisting of BYK-111, BYK-103 and a silane coupling agent. 11. The method of claim 10,
Wherein the additive amount of the dispersant is 0.2 to 1.5 wt% based on the total amount of the first metal powder and the second metal powder when the first metal powder and the second metal powder are dispersed, respectively. The method according to claim 1,
Wherein the solvent is at least one selected from the group consisting of methyl ethyl ketone (MEK), ethanol, IPA, toluene, and xylene. The method according to claim 1,
Wherein the resin is an epoxy resin. 15. The method of claim 14,
The epoxy resin may be a novolac epoxy resin, a phenoxy type epoxy resin, a BPA type epoxy resin, a BPF type epoxy resin, a hydrogenated BPA epoxy resin, Hydrogenated BPA epoxy resin, dimer acid modified epoxy resin, urethane modified epoxy resin, rubber modified epoxy resin and DCPD type epoxy resin (DCPD type epoxy resin). < RTI ID = 0.0 > 11. < / RTI > The method according to claim 1,
Wherein the curing is performed in a temperature range of 120 to 200 ° C. 17. The method of claim 16,
Wherein the curing is performed for 10 minutes to 1 hour.

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