KR20210079878A - Surface roughness Improving Method of Substrate and Substrate Using the Same - Google Patents

Abstract

The present invention provides a substrate having excellent quality by improving surface roughness through a method for improving surface roughness, including the steps of: a) preparing a substrate; b) polishing the surface of the substrate to form open pores on the surface; c) applying nanoparticle suspension to fill the open pores on the surface of the substrate; d) improving adhesion between nanoparticles and the substrate through optical sintering or thermal sintering to the substrate to which the nanoparticle suspension is applied.

Description

TECHNICAL FIELD [0002] Surface roughness Improving Method of Substrate and Substrate Using the Same

The present invention relates to a method for improving the surface roughness of a substrate and a substrate with improved surface roughness using the same, and more particularly, to a method for improving the surface roughness of a substrate using nanoparticles and a substrate with improved surface roughness using the same will be.

Precision parts used in mobile phones, computers, electronic parts, industrial parts, etc. are manufactured by various methods, for example, die casting, injection molding, etc., and then metal coating is applied to the surface by applying a plating process. However, due to the nature of the manufacturing method, the micropores formed on the surface and inside of the final material cause a partial height difference on the surface, thereby reducing the quality of the final product.

In this regard, FIG. 1 is a cross-sectional view of a substrate coated with a paint according to the prior art.

According to Figure 1, the conventional substrate has pores formed on the surface and inside of the final material due to the characteristics of the manufacturing method. Therefore, when a paint is coated after polishing by a conventional method, pores burst, swell, dent, etc. during the drying and curing of the paint. In some cases, the quality of the final product was deteriorated as a problem of

Accordingly, there was an effort to solve this problem by using metal nanoparticles, but there was a problem in that the thickness of the additionally formed printed layer due to the roughness due to the size of the metal nanoparticles itself becomes non-uniform. In addition, since the adhesion between the metal nanoparticles and the substrate was weak, a problem occurred in which the plating layer was detached in the course of use, and thus the performance was deteriorated.

Accordingly, while solving these problems, there is a need for a coating technology that can replace the plating process in order to apply eco-friendly surface treatment technology.

An object of the present invention is to solve the problems of the prior art as described above and the technical problems that have been requested from the past.

Specifically, an object of the present invention is to provide a method for improving the surface roughness of a substrate using nanoparticles.

Another object of the present invention relates to a substrate having excellent overall properties by improving the surface roughness using the above method.

The present invention is

A) preparing a substrate;

b) polishing the surface of the substrate to form open pores on the surface;

c) applying a nanoparticle suspension to fill the open pores on the surface of the substrate;

D) improving the adhesion between the nanoparticles and the substrate through optical sintering or thermal sintering to the substrate to which the nanoparticle suspension is applied; provides a method for improving the surface roughness of a substrate, including.

In one embodiment, the step c) is,

c-1a) forming a nanoparticle sealing layer by applying a nanoparticle suspension to fill the open pores on the surface of the substrate; and

C-1b) grinding the portion of the nanoparticle sealing layer exposed on the surface of the substrate; may include.

In another embodiment, the step c) is,

c-2a) image analysis of the open pores formed on the surface of the substrate; and

c-2b) selectively applying the image-analyzed open pores with a nanoparticle suspension; may include.

In step c-2b), the application may be performed by a nozzle spray process.

Step c) may be performed under a vacuum atmosphere.

In step d), the light treatment may be performed by irradiating intense pulsed light (IPL).

In step d), the heat treatment may be performed by heating to 50 to 300° C., maintaining for 5 to 150 minutes, and then cooling to room temperature.

In addition, the present invention, after performing step d),

E) a level coating step of applying an acrylic compound to the optically sintered or thermally sintered substrate; may be further included.

The present invention is

Provided is a substrate having improved surface roughness by using the method for improving surface roughness.

The substrate may have a surface roughness improved by 50 to 95%.

According to one embodiment of the present invention, since the open pores can be selectively filled by applying nanoparticles to the open pores formed by grinding the substrate, the roughness of the substrate can be improved and the surface roughness can be improved. In addition, after the open pores are filled using the nanoparticles, post-treatment through optical sintering or thermal sintering is performed, so that the adhesion between the nanoparticles and the substrate is improved, thereby providing a substrate having excellent adhesion.

According to another embodiment of the present invention, the plating process can be replaced by a simple and eco-friendly method because it proceeds including the step of level coating after filling the open pores using nanoparticles.

1 is a cross-sectional view of a substrate coated with a paint according to the prior art;
Fig. 2(a) is a cross-sectional view of the substrate;
Fig. 3 (a) is a cross-sectional view of a substrate having open pores on its surface, and Fig. 2 (b) is a photograph taken after polishing the surface of the aluminum alloy injection product;
4 (a) and (b) are schematic diagrams showing the application process of the nanoparticle suspension according to an embodiment of the present invention;
5 is a schematic diagram showing a process of applying a nanoparticle suspension according to another embodiment of the present invention;
6 is a cross-sectional view of a substrate having a level coating layer formed thereon;
7 is a photograph of a substrate according to an experimental example;
8 is an enlarged photograph and 3D image of a substrate according to an experimental example; and
9 is an FE-SEM photograph of a substrate having improved surface roughness according to an experimental example.

Hereinafter, an embodiment of the present invention will be described in more detail with reference to FIGS. 2 to 9 .

2 to 6 are views showing each step of the method for improving the surface roughness of the substrate according to the embodiment of the present invention.

First, as shown in FIG. 2 , the substrate 100 is prepared in step (a).

The substrate 100 may be, for example, a metal material used as an exterior material for electronic products, such as aluminum, aluminum alloy, magnesium, magnesium alloy, ceramic, SUS, copper, or alloys thereof, and specifically, aluminum or its It may be manufactured by die casting in the form of a metal as an alloy.

Due to the characteristics of the die-casting manufacturing process of the substrate 100 , the surface may be roughly formed and may have a plurality of pores 200 therein. Since it is necessary that the substrate 100 does not have a thick oxide film, hydroxide film, etc., a degreasing process, etching process, washing process, etc. for removing foreign substances and oil from the surface as a pretreatment process can be selectively performed.

Next, as shown in FIG. 3(a), in step (b), the surface of the substrate 100 is polished to confirm the open pores 210 formed on the surface.

In order to improve the roughness of the surface of the substrate 100 roughly molded by injection, a polishing process is generally performed. At this time, the pores inside are exposed and the surface roughness may be worse. Therefore, the present invention can improve the surface roughness, including the process of filling the exposed internal pores, that is, the open pores (210).

Specifically, the substrate 100 that has undergone the polishing process may have open pores 210 exposed on the surface of the substrate 100 and closed pores 220 formed inside the substrate 100 .

The polishing method may use one or more of electropolishing, mechanical, chemical, and physical polishing, but is not limited thereto.

In this regard, Figure 3 (b) is a photograph taken after polishing the surface of the aluminum alloy injection molding.

Referring to FIG. 3(b), it can be seen that a plurality of open pores are observed while the pores inside are exposed when the surface of the aluminum alloy is polished. These open pores cause deterioration of the surface roughness of the substrate. Accordingly, in the present invention, the nanoparticle suspension may be applied to fill the open pores 210 on the surface of the substrate 100 as will be described below.

The nanoparticle suspension may be in the form of an ink or paste as a suspension containing the nanoparticles. The nanoparticles may be metal nanoparticles such as copper, aluminum, gold, or silver, oxide nanoparticles such as silica, or polymer nanoparticles, but is not limited thereto.

The nanoparticle suspension may include a solvent other than nanoparticles, other additives, and the like, but is not limited thereto. The solvent may be deionized water, alcohol or ammonia water, but is not limited thereto.

Specifically, Figure 4 (a) and (b) is a schematic diagram showing the application process of the nanoparticle suspension according to an embodiment of the present invention.

As shown in FIG. 4(a), in step (c-1a), the nanoparticle encapsulation layer 300 may be formed by applying a nanoparticle suspension to fill the open pores 210 on the surface of the substrate 100. have.

The application is not particularly limited as long as it is a commonly performed method, but, for example, may be performed by any one method selected from roll coating, spraying, immersion, spray squeezing and immersion squeezing.

Due to the nature of the fine nanoparticles, in the application process, the nanoparticles can be located not only on the open pores 210 but also on the surface of the substrate 100 , so that the nanoparticle sealing layer 300 is a nanoparticle sealing layer exposed over the surface of the substrate 100 . It consists of a portion 320 and a nanoparticle encapsulation layer portion 310 that fills the open pores.

Accordingly, as shown in FIG. 4(b), the nanoparticle sealing layer portion 320 exposed on the surface of the substrate 100 in step (c-1b) may be polished. The nanoparticle sealing layer portion 320 exposed over the surface of the substrate 100 through the polishing process is removed, and the surface of the substrate 100 and the surface of the nanoparticle sealing layer portion 310 filling the open pores are on the same surface. Since it is positioned so that the surface of the substrate 100 can be formed flat, the surface roughness can be improved.

For the polishing, electrolytic polishing, mechanical, chemical, and physical polishing processes may be used depending on the type and size of the substrate 100 and nanoparticles, for example, ceramic abrasive such as sand and bead blasting, SiC paper, etc. It may be carried out by a phosphorus method or a chemical method of precipitation in washing water of 25 to 35° C. for 10 to 30 minutes, but is not limited thereto.

The nanoparticles are metal nanoparticles such as copper, aluminum, gold, silver, etc., oxide nanoparticles such as silica, or polymer nanoparticles. can be used without

The nanoparticle suspension may be in the form of an ink or paste as a suspension containing the nanoparticles. The nanoparticle suspension may include a solvent other than nanoparticles, other additives, and the like, but is not limited thereto. The solvent may be deionized water, alcohol or ammonia water, but is not limited thereto.

As shown in FIG. 5 , the open pores formed on the surface of the substrate 100 in step (c-2a) may be analyzed as an image.

The image may be analyzed through an image forming apparatus (not shown), and the image forming apparatus analyzes the position of the open pores formed on the surface of the substrate 100 so that only the open pores are selectively filled with the nanoparticle suspension. make it possible

Specifically, the nanoparticle suspension may be selectively applied to the open pores analyzed by image in step (c-2b) to form the open pores 410 filled with nanoparticles.

The application may be performed using the nozzle 500 . The nozzle 500 is for selectively ejecting the nanoparticle suspension into the open pores at high speed, spaced apart from the open pores at a predetermined interval and connected to the upper flow path (not shown), and You can get information about your location. When ejecting the nanoparticle suspension, if the ejection is small in a high pressure state, the pressure energy is converted into velocity energy, so that the open pores 410 filled with nanoparticles can be quickly formed.

The nanoparticles may be used without limitation as long as they are metal nanoparticles such as copper, aluminum, gold, or silver, oxide nanoparticles such as silica, or polymer nanoparticles.

The particle diameter of the nanoparticles may be 1 to 500 nm, specifically 10 to 250 nm. If the particle diameter of the nanoparticles is too small outside the above range, difficulties in the process may occur, and if it is too large, the pores between the nanoparticles increase in the process of filling the open pores, or it is not preferable because it becomes difficult to fill the small open pores.

The nanoparticle suspension may be in the form of an ink or paste as a suspension containing the nanoparticles. The nanoparticle suspension may include a solvent other than nanoparticles, other additives, and the like, but is not limited thereto. The solvent may be deionized water, alcohol or ammonia water, but is not limited thereto.

The viscosity of the nanoparticle suspension may be 10 to 300,000 cP. If the viscosity of the nanoparticle suspension is too small outside the above range, it is difficult to obtain the intended effect of the present invention, and if the viscosity is too large, difficulties in the process may occur.

In the present invention, the process of applying the nanoparticle suspension of step (c) may be made under a vacuum atmosphere.

Such a vacuum atmosphere allows the nanoparticle suspension applied to the substrate 100 to be filled into the open pores without air bubbles, so that ultimately, a substrate with improved surface roughness can be obtained.

In the present invention, the surface roughness of the substrate is improved by filling the open pores 210 located on the substrate 100 using the nanoparticle suspension, while the adhesion between the nanoparticles and the substrate 100 is improved through the post-treatment process. while removing impurities other than nanoparticles.

As an example, optical sintering may be performed in step (d).

Such optical sintering can be accomplished by irradiating intense pulsed light (IPL), and sintering can be performed within a short time without damage to the substrate at room temperature and atmospheric pressure, thereby enabling selective sintering with high sintering penetration. The optical sintering using the IPL can be made through, for example, plasmonic welding by irradiation with a Xenon lamp, and by appropriately controlling the wavelength of the irradiated light, the adhesion of the nanoparticles is improved using less than UV 400 nm. and substrate surface cleaning through impurity removal using NIR greater than 700 nm.

As another example, thermal sintering may be performed in step (d).

This thermal sintering may be accomplished through a process of cooling to room temperature after heating and maintaining for a certain period of time, specifically, heating to 50 to 300° C. and maintaining for 5 to 150 minutes, and then cooling to room temperature. . When the heating temperature and the temperature holding time are out of the above-defined ranges, there is a risk that the substrate may be damaged or the efficiency of the process may be lowered, which is not preferable. In the cooling step, the cooling may use a fluid or water, specifically, may use a fluid or sprayed water such as fine droplets.

FIG. 6 is a schematic diagram showing the level coating layer 600 formed in the filled open pores 310 of the substrate 100 as another embodiment.

When the open pores are filled, since the level coating layer 600 can be easily formed, the plating process can be replaced by a simple and eco-friendly method, and surface roughness of the plating level can be provided.

The level coating layer may be formed by applying a suspension containing an acrylic compound.

The acrylic compound is an acrylic monomer; and an acrylic oligomer.

The acrylic monomer is, for example, methyl methacrylate, methyl acrylate, ethyl acrylate, styrene, 2-ethylhexyl acrylate, butyl acrylate, 2-hydroxyethyl methacrylate, 2-hydroxyethyl acrylic Late, 2-hydroxypropyl acrylate, hydroxybutyl acrylate may be one or more from the group consisting of methacrylic acid, acrylic acid and itaconic acid, but is not limited thereto.

The acrylic oligomer may be an oligomer of the acrylic monomer, and in some cases, may be at least one selected from the group consisting of a urethane-modified acrylate oligomer, an ether acrylate oligomer, and an ester acrylate oligomer, but is not limited thereto.

Thereafter, the acrylic compound may be cured through heat, ultraviolet light, or the like.

On the other hand, the present invention provides a substrate with improved surface roughness by using the method for improving the surface roughness of the substrate.

In the substrate 100 according to the present invention, the open pores 210 are filled with nanoparticles, and the surface roughness of the substrate 100 is improved through a post-treatment process such as light sintering or thermal sintering, while the nanoparticles and the substrate Adhesion may be improved.

Accordingly, the level coating layer 600 can be formed more easily to replace the plating process in a simple and eco-friendly way, and it is possible to provide a surface roughness of the plating level. That is, in the plating process, wastewater containing a large number of heavy metals or light metal ions is generated, but the method according to the present invention is very environmentally friendly because it is possible to minimize the generation of wastewater because it does not go through the plating process.

Since the substrate to which the process according to the present invention is applied is improved to 50 to 95%, specifically 55 to 90%, compared to the base material, it is possible to minimize bursting, swelling of the painted surface, denting, etc. occurring from the pores of the base material. The above range is an optimal range in consideration of the manufacturing process, economic feasibility, and the like.

Specifically, the surface roughness (Ra) of such a substrate may be 10 nm to 2 um, specifically 10 nm to 1.8 um.

Hereinafter, examples of the present invention will be described in detail. However, the following examples are merely illustrative of the present invention, and the content of the present invention is not limited to the following examples.

Experimental example

Under the following experimental conditions, an aluminum substrate was prepared, the surface was polished, a copper oxide suspension was applied, the sealing layer portion exposed on the surface was polished, and the substrate surface was improved by performing optical sintering. This is shown in Table 1, Figures 7, 8 and 9.

- Al substrate surface treatment: O ₂ plasma, 150 W, 300 sec

-Material for screen printing: Water-based CuO ink, > 50 wt%, ~250 nm, ~300,000 cP

-IPL process conditions after coating: 3 kV, 1320 ms (pulse width), 1/3/5/10/20 shots

Rp(um) Rv(um) Rz(um) Ra(um) Rq(um) Before coating 47.117 63.437 110.554 2.835 4.090 After coating 39.578 47.211 86.789 1.915 3.036 After IPL 26.681 22.465 49.146 1.594 2.190

Referring to Table 1 and FIGS. 7 to 9 , it can be seen that the surface roughness (Ra) of the substrate prepared according to the present invention is improved compared to the surface roughness (Ra) of the base material before coating. In particular, referring to FIG. 9 , it can be confirmed that the copper nanoparticles are filled in the fine portions such as pores or scratches, thereby improving the surface roughness.

100 entries
200 pore
210 open pore
220 closed pore
300 nanoparticle sealing layer
310 Part of the nanoparticle sealing layer filling the open pores
320 Part of the nanoparticle encapsulation layer exposed over the substrate surface
Open pores filled with 410 nanoparticles
500 nozzles
600 level coating layer

Claims (10)

A) preparing a substrate;
b) polishing the surface of the substrate to form open pores on the surface;
c) applying a nanoparticle suspension to fill the open pores on the surface of the substrate;
D) improving the adhesion between the nanoparticles and the substrate through optical sintering or thermal sintering to the substrate to which the nanoparticle suspension is applied; and According to claim 1, wherein the step c),
c-1a) forming a nanoparticle sealing layer by applying a nanoparticle suspension to fill the open pores on the surface of the substrate; and
c-1b) polishing the portion of the nanoparticle sealing layer exposed on the surface of the substrate; According to claim 1, wherein the step c),
c-2a) image analysis of the open pores formed on the surface of the substrate; and
C-2b) The method of improving the surface roughness of a substrate, comprising: selectively applying the nanoparticle suspension to the open pores analyzed by the image. [4] The method of claim 3, wherein the application in step c-2b) is performed by a nozzle spray process. The method of claim 1, wherein step c) is performed under a vacuum atmosphere. The method of claim 1, wherein the light treatment in step d) is performed by irradiating intense pulsed light (IPL). The method of claim 1, wherein the heat treatment in step d) is performed by heating to 50 to 300° C. and maintaining it for 5 to 150 minutes, followed by cooling to room temperature. The method of claim 1, wherein after performing step d),
E) a level coating step of applying an acrylic compound to the photo-sintered or thermally sintered substrate; A substrate having improved surface roughness by using the method according to claim 1 . The substrate according to claim 9, wherein the surface roughness of the substrate is improved by 50 to 95%.

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