KR100770048B1 - Etching method for electroless plating - Google Patents

Abstract

The present invention relates to an etching method for electroless plating, and more particularly, to etching the metal, which is essential for metallization of plastics, but replacing a chemical etching method, which is a typical environmental pollution causing process, with a low environmental load type process using photoelectrochemical reactions. It is about a method.

Immersing a plastic part in a colloidal solution suspended in nano-sized titanium dioxide sol state in one aspect of the present invention for achieving the above object; And irradiating a light source to the immersed plastic part. An etching method for electroless plating is provided.

 According to the present invention, by using a titanium dioxide sol as a photocatalyst, a component having an etched surface having an appropriate roughness can be produced, which is effective for electroless plating.

Electroless Plating, Photocatalyst, Titanium Dioxide, Etching, Sol

Description

Etching Method for Electroless Plating {ETCHING METHOD FOR ELECTROLESS PLATING}

1 is a graph showing the results of X-ray diffraction analysis of a titanium dioxide sol prepared according to the present invention;

FIG. 2 is a photograph showing the results of preparing a sol by replacing part of titanium with vanadium (V), chromium (Cr), iron (Fe), nickel (Ni), and niobium (Nb) in a titanium dioxide sol. ;

3 is an X-ray diffraction analysis of a result of preparing a sol by replacing a part of titanium in the titanium dioxide sol with vanadium (V), chromium (Cr), iron (Fe), nickel (Ni) and niobium (Nb). Graph showing results;

Figure 4 is a graph showing the particle size analysis results measured by the dynamic light scattering method (Photal Otsuka Electronics Co., Ltd. ELS 8000) 10 times for the titanium dioxide sol prepared according to the present invention;

Figure 5 is a graph showing the results of the light absorption test by UV-VIS spectrometer for a sol prepared by replacing a part of titanium with a transition element;

6 is a schematic diagram showing an apparatus for performing photocatalytic etching;

7 is a photograph of electron microscope results of observing a plastic surface photocatalyst etched by a titanium dioxide sol prepared according to the present invention;

8 is a photograph of electron microscope results of observing the surface of the plastic photocatalyst etched by the suspension of titanium dioxide powder prepared according to the present invention suspended in deionized water;

9 is an electron microscope photograph of the observation of the acid-etched plastic surface;

10 is a result of electroless plating on the etched plastic surface, (a) is a result of electroless plating on a photocatalyst etched plastic surface with titanium dioxide sol according to the present invention, (b) is acid etched for comparison Photograph showing the result of electroless plating on the plastic surface; And

FIG. 11 is a graph showing the results of X-ray diffraction analysis on titanium dioxide sol containing a large amount of brookite as a titanium dioxide sol prepared according to the present invention.

The present invention relates to an etching method for electroless plating, and more particularly, to etching the metal, which is essential for metallization of plastics, but replacing a chemical etching method, which is a typical environmental pollution causing process, with a low environmental load type process using photoelectrochemical reactions. It is about a method.

Electroless plating, also called chemical plating or self-catalyst plating, is a method of depositing metal on the surface of a workpiece by reducing the metal ions in an aqueous metal salt solution catalytically by means of a reducing agent without receiving electrical energy from the outside. Say how.

In other words, conventional electroplating refers to a plating method in which a metal to be dissolved in an electrolyte solution is deposited on the surface of an article to be plated by flowing the electricity as a cathode and electroless plating. Way.

Therefore, electroless plating is widely used for surface plating of parts having a material such as plastic, which cannot or cannot be supplied with electricity.

As described above, in the electroless plating, unlike the conventional electroplating method, since electron exchange is not performed by electricity supply, a separate electron exchange process for precipitation of ions in the electrolyte needs to be performed. For the electron exchange process, a reducing agent for supplying electrons to metal ions needs to be included in the electrolyte. However, if the activation energy of the reduction reaction is low enough to reduce the metal ion as soon as it comes into contact with the metal ion to be deposited (plated), the metal ion is not deposited only on the surface of the component, but the metal ion is deposited at all parts of the electrolyte. It becomes impossible to obtain plating effect.

Therefore, the reduction reaction of the metal ion by the reducing agent present in the electrolyte together with the metal ion is controlled to require a certain value or more activation energy. In this case, a catalyst for reducing the activation energy is attached to the surface of the component so that metal ions are selectively precipitated only on the surface of the component made of a material such as plastic to achieve a plating effect. The catalyst is mainly used a lot of metal, Pd, Ag, Au or Pt, etc. are used as the metal, and the most common catalyzing method is Pd-Sn colloid method. In addition, the metal catalyst also serves to provide a nucleation site for allowing the deposited metal to be easily precipitated.

At this time, it is necessary to modify the plastic surface so that the metal catalyst can be easily present on the plastic surface, a method of etching the surface is commonly used to facilitate the contact and adhesion of the catalyst. When the plastic surface is etched, the plastic surface turns into a rough surface with a large roughness, and according to this surface property, a metal catalyst can be easily attached to the plastic surface.

Conventionally, as the plastic etching method, an acid etching method in which a plastic is immersed in a strong oxide acid such as chromic acid-sulfuric acid or phosphoric acid is commonly used. This acid etching method has the advantage of simple process and excellent surface roughness improvement effect by etching, but it has problems such as generation of human harmful substances that strongly irritate the skin and mucous membrane of worker and continuous increase of environmental treatment cost. .

As an alternative process for solving the problems of the acid etching method, a dry plasma surface treatment method has emerged. The dry plasma surface treatment method has a problem that it is difficult to easily introduce due to problems such as a continuous process is difficult and equipment is expensive.

In order to solve the above problems, there is a need for an etching method that does not require expensive equipment and does not cause environmental pollution by a simple process, which is a method using a photocatalyst.

The photocatalyst technology, which has been studied in the US, Europe, and Japan as a new future technology in the environment since the late 1980s, utilizes the strong oxidation power of the hydroxyl radicals generated when the photocatalyst receives light.

Particularly, a material that is spotlighted as the photocatalyst material may include TiO ₂ , wherein when TiO ₂ is irradiated with light having a short wavelength of 400 nm or less corresponding to an energy of 3.0 to 3.2 eV, electrons in the valence band are conducting as It has a semiconductor characteristic to be excited.

By the reaction, electrons and holes are formed. The electrons and holes move to the TiO ₂ surface, and the transferred electrons and holes recombine or cause an oxidation-reduction reaction with surrounding materials. In particular, when water is present around the hole of the valence band reacts with hydroxyl groups to form hydroxyl radicals (OH), and when oxygen is present, it combines with electrons in the conduction band to form super oxides (O ₂ ⁻ ). Photoactive species such as hydroxyl radicals and super oxides play a key role in the photocatalytic reaction, and each has a strong oxidation and reducing power, and thus has a very strong reactivity with surrounding materials.

The reaction that occurs due to the strong reactivity of the hydroxyl radical and the super oxide can be various, one of which is the etching effect on plastics. That is, the above-mentioned photoactive species such as hydroxyl radicals and super oxides play a role of decomposing plastics by reacting with plastics, and the like, to obtain a plastic having a rough surface by the decomposition reaction of the plastics.

For this reason, a photoelectrochemical etching method of the TiO ₂ photocatalyst has been conventionally proposed, which is a method of photoetching the surface of a plastic by contacting the plastic with coarse size powdery TiO ₂ in the presence of moisture.

However, in this case, the size of the TiO ₂ powder used is coarse, making it difficult to evenly etch the entire plastic surface, and there is a problem that the etching surface becomes rough. Of course, as described above, the etching surface needs to have a roughness of a certain level or more, but if the etching surface is too rough, the surface of the plating layer is not flat, which is disadvantageous in pattern formation when patterning is used for use in a semiconductor substrate. As a result, roughness above the appropriate level may affect subsequent processes. In addition, TiO ₂ powders tend to have a strong tendency to agglomerate with each other under normal conditions, and this tendency further exacerbates the problems caused by the coarse powder.

In addition, apart from these problems, the TiO ₂ photocatalyst powder used in an etching process using a conventional photocatalyst has a problem that its use is limited because it has a photocatalyst characteristic that responds only to light having a wavelength in the ultraviolet band.

Titanium dioxide is present in three forms, anatase, rutile and brookite, all of which have properties suitable for photocatalysts, and particularly preferably include a large amount of brookite phase.

If described in detail the anatase phase and the rutile crystallographically TiO ₂ has the crystal structure of the tetragonal system, Brook kite the TiO ₂ is while having a crystal structure of orthorhombic depending on the combination of the Ti ions and the oxygen atoms manner different physical Has characteristics. That is, the anatase phase and the rutile phase TiO ₂ are bonded to oxygen atoms in one type, ie, symmetrical structures, while the metastable Brookite phase TiO ₂ has a crystal structure that is bonded to oxygen atoms in an asymmetric structure. More specifically, the brookite TiO ₂ is a TiO ₆ octahedron with six asymmetric oxygen atoms bonded to the central Ti ion, and each octahedron shares an edge with three neighboring octahedrons in the [100] direction. It grows to form a structure with a long tunnel in the c axis with respect to the crystal axis. This structural feature is advantageous for the capture of relatively small ionic radii and much more advantageous for the provision of large area reaction sites for photocatalytic reactions.

However, since the brookite phase is present as a metastable phase at room temperature, there is no problem in obtaining a pure brookite phase because there is no quantified manufacturing method, and thus, the anatase and rutile phases are widely used commercially.

The present invention has been made to solve the above problems, and an object thereof is to provide an etching method using a photocatalyst which provides an etching surface having an appropriate roughness.

It is another object of the present invention to provide a photocatalyst etching method which is responsive not only in the ultraviolet region but also in the visible region.

In addition, another object of the present invention is to provide a method for photocatalyst etching using a titanium dioxide sol containing a large amount of brookite phase having excellent dispersibility and excellent photocatalyst efficiency.

Immersing a plastic part in a colloidal solution suspended in nano-sized titanium dioxide sol state in one aspect of the present invention for achieving the above object; And irradiating a light source to the immersed plastic part. An etching method for electroless plating is provided.

At this time, the titanium dioxide sol, a neutralizing reaction by mixing a neutralizing agent in an aqueous solution of titanyl chloride to obtain a titanium dioxide-based hydrate; Washing and filtering the titanium dioxide based hydrate; Immersing and dissolving the titanium dioxide-based hydrate in an aqueous solution in which a hydrogen peroxide of 8 to 10 times the number of moles of titanyl chloride ion is dissolved; And the titanium dioxide-based hydrate can be prepared by a titanium dioxide sol manufacturing process consisting of a step of obtaining a titanium dioxide sol by hydrothermal synthesis by putting the solution dissolved in the aqueous hydrogen peroxide solution into an autoclave.

According to yet another aspect of the present invention, a method of preparing a colloidal solution in which titanium dioxide is suspended in a sol state by suspending titanium dioxide nano powder having a size of primary particles of 30 nm or less in water; Dipping a plastic part in a colloidal solution in which the titanium dioxide is suspended in a sol state; And irradiating a light source to the immersed plastic part. An etching method for electroless plating is provided.

At this time, the nano-sized titanium dioxide powder, the neutralizing by mixing a neutralizing agent in an aqueous solution of titanyl chloride to obtain a titanium dioxide-based hydrate; Washing and filtering the titanium dioxide based hydrate; Immersing and dissolving the titanium dioxide-based hydrate in an aqueous solution in which a hydrogen peroxide of 8 to 10 times the number of moles of titanyl chloride ion is dissolved; Obtaining a titanium dioxide sol by hydrothermally synthesizing a solution in which the titanium dioxide-based hydrate is dissolved in the aqueous hydrogen peroxide solution in an autoclave; And freeze-drying the titanium dioxide sol; it can be prepared by the titanium dioxide powder manufacturing process consisting of. In addition, the lyophilization is carried out under a vacuum of less than 300mtorr in the temperature range of -40 ~ -60 ℃.

The titanyl chloride aqueous solution used in the above-described process is prepared by dropping ice or ice water frozen in distilled water into titanium tetrachloride solution to produce yellow and hard titanium tetrachloride as an intermediate step, and then adding more water to it and dissolving the titanium ion concentration. It can be made to be 1.5M or more.

Moreover, as an operating condition of an autoclave, when the pressure in an autoclave is not specifically controlled, it is preferable that the temperature in the said autoclave is 80-140 degreeC, and it is more preferable that it is 110-130 degreeC.

However, when adjusting the pressure in the autoclave to 30 ~ 100bar, the temperature in the autoclave can be controlled in the range of 80 ~ 180 ℃.

At this time, the time of hydrothermal synthesis in the autoclave is preferably 3 to 24 hours.

Then, before the neutralizing agent is mixed with the aqueous titanyl chloride solution, one or two or more transition metal compounds of a transition metal compound including a transition metal element substituted with titanium of the titanyl chloride solution and a transition metal compound are added. It is possible to obtain a titanium dioxide sol in which the metal is partially substituted, and to produce a photocatalyst that is responsive in the visible region.

In this case, the transition metal preferably includes one selected from chromium (Cr), nickel (Ni), vanadium (V), niobium (Nb), or iron (Fe).

In addition, it is effective that the intensity of light irradiated to the component during the photocatalyst etching is 3 to 60 mW / cm ² .

When using a titanium dioxide sol containing a metastable brookite phase as the titanium dioxide sol used for the photocatalyst etching, by adjusting the pressure in the autoclave to 35 ~ 100bar, the temperature to 80 ~ 180 ℃ You need to keep it for more than 7 hours.

Hereinafter, the present invention will be described in detail.

The inventors have simply TiO ₂ having a fine particle size, even if any method when using TiO ₂ is formed as a result, simply powder research to solve the problems of the conventional method was used for the optical etching by suspending the powder of TiO ₂ in water We conclude that we cannot solve the problem that we cannot obtain and therefore only a part of the surface is etched or a surface with a very rough surface is obtained.

Therefore, in order to solve the above problem, the present inventors have found that the etching surface having an appropriate degree of roughness and uniform roughness can be obtained on the entire surface of the plastic when photoetching by allowing TiO ₂ to exist in a nano-sized sol state. I could tell the truth.

Therefore, the present invention consists of immersing a plastic part in a colloidal solution in which nano-sized titanium dioxide is suspended in a sol state, and irradiating a light source to the immersed plastic part.

The wavelength of the light source to be irradiated may be appropriately selected from the ultraviolet band or the visible light + ultraviolet band according to the component of the titanium dioxide sol described later.

At this time, the intensity of light irradiated to the component is preferably irradiated in the range of 3mW / cm ² to 60mW / cm ² to the component to be etched. If the light intensity is less than 3mW / cm ² , the photocatalytic etching effect is difficult to obtain even after long-term etching. If the light intensity exceeds 60mW / cm ² , the temperature of the sol solution increases or the surface of the specimen to be etched due to excessive heat generation. There is a problem of overetching. In addition, in order to obtain sufficient photocatalytic etching effect, it is preferable to irradiate light for 10 minutes or more.

However, the irradiation time is preferably limited to within 60 minutes because 60 minutes irradiation can obtain a sufficient effect.

In addition, as a precursor for preparing a colloidal solution in which TiO ₂ is suspended in a sol state, one prepared by dissolving titanium dioxide hydrate, for example, titanium peroxo (TiO (OH) ₂ ) in an aqueous hydrogen peroxide solution It is preferable to use. When titanium dioxide based hydrate is added and stirred to the aqueous hydrogen peroxide (H ₂ O ₂ ) solution, the titanium dioxide based hydrate is changed to a compound such as TiO (OH) (OOH), and the subsequent heating is followed by TiO (OH) (OOH). The process undergoes a solvation reaction in which TiO ₂ is formed. Concentration of a suitable hydrogen peroxide aqueous solution for dissolving the titanium peroxo is preferably 0.08 ~ 5M, when preparing titanium dioxide hydrate using titanyl chloride as described below, 8 ~ 10 of the concentration of titanyl chloride Preferably, the concentration of the pear (when the ratio of the volume of the aqueous solution of titanyl chloride and the aqueous solution of hydrogen peroxide is 1: 1). That is, the number of moles of hydrogen peroxide in the aqueous hydrogen peroxide solution is about 8 to 10 times the number of moles of titanyl chloride. If the concentration is too low, it is difficult to completely dissolve the titanium dioxide hydrate. On the contrary, if the concentration is too high, the nucleation temperature is increased due to saturated hydrogen peroxide solution.

The heating step in which the TiO (OH) (OOH) is heated is to help dissolution of the titanium peroxo and to facilitate condensation polymerization of TiO (OH) (OOH) to cause a transition to TiO ₂ . At this time, the heating is preferably carried out in a hydrothermal synthesis in an autoclave type container so that condensation polymerization occurs easily. The autoclave is preferably made of Teflon or coated with Teflon.

Moreover, it is preferable that the temperature of the said heating process is 80-140 degreeC. If the heating temperature is less than 80 ° C., the reaction time becomes too long, the particle size of the sol-forming particles increases, and the amount of undissolved titanium peroxo increases, which is disadvantageous for sol formation. On the contrary, when the heating temperature exceeds 150 ° C., the pressure inside the reaction vessel is increased and condensation polymerization is excessively activated, and as a result, the size of the sol particles is too large. Most preferred heating temperature is in the range of 110-130 ° C. However, when the pressure in the autoclave is set at a high pressure in the range of 30 to 100 bar, it can be manufactured without increasing the size of the particles up to 180 ° C.

It is necessary to carry out heating process for a certain time so that TiO (OH) (OOH) is sufficiently phase-changed with TiO _{2. At} the appropriate reaction temperature, it is necessary to maintain at least about 8 hours, and in order to dissolve the undissolved titanium peroxo sufficiently. It is most preferable to keep it for 10 hours or more. In addition, if the holding time is about 24 hours, not only is sufficient, but additional effects are hardly expected even if the holding time is longer, so the upper limit of the holding time is limited to 24 hours.

The particle size of the titanium dioxide sol obtained through the above process is 30nm or less, it is possible to obtain a titanium dioxide sol having a very fine particle diameter.

At this time, if the present titanium dioxide sol to be produced on the Brookkite it is necessary to control the conditions in the autoclave more closely. That is, the inventors of the present invention have repeatedly studied the conditions for preparing the form of titanium dioxide present in the sol as the Brookkite phase, and found that it is necessary to increase the pressure for hydrothermal synthesis in the autoclave and to perform the treatment for a long time. The photocatalyst etching method using the Brookkite phase, which is another aspect of the present invention, can be derived.

That is, in order to manufacture titanium dioxide on brookite, it is necessary to maintain the temperature at the time of hydrothermal synthesis in an autoclave at 80-180 degreeC or more, and the pressure about 35-100 bar. When the temperature is low, the reaction time becomes too long, and when the temperature is too high, the particle size increases. In addition, if the pressure is less than 35bar, titanium dioxide on the anatase is mainly formed, and it is not preferable because the pressure control is difficult when it exceeds 100bar.

In addition, since the amount of the produced Brookkite phase is less at the time of less than 7 hours even if the treatment at the pressure, it is required to be treated for at least 7 hours to obtain a titanium dioxide sol formed properly.

However, since the pressure in the autoclave depends on the temperature, when the temperature is determined as described above, the pressure range is inevitably limited to a certain level or less. Therefore, in order to increase the pressure of the autoclave it is necessary to compensate the pressure to a certain level or more, it is preferable to secure the pressure to be compensated by injecting nitrogen, argon, compressed air and the like into the autoclave.

Apart from the method described above, when the titanium dioxide sol prepared by the above method is dried by a special method, it is a nano-sized titanium dioxide powder, which has almost no self-cohesion, and has excellent dispersibility when it is added to a dispersion medium such as water in the future. It can also be used as a titanium dioxide sol. That is, the colloidal solution in which the titanium dioxide used in the photocatalytic etching of the present invention is suspended in the form of sol is prepared by drying the titanium dioxide sol solution by a special method to produce titanium dioxide powder and then suspending the titanium dioxide powder in a dispersion medium again. You may.

At this time, the drying method for obtaining the titanium dioxide powder is as follows. In order to obtain the titanium dioxide powder, the titanium dioxide sol obtained by the above-mentioned sol preparation process may be lyophilized with a vacuum of 300 mtorr or less in a temperature range of -40 to -60 ° C. The titanium dioxide powder obtained by drying in this manner is a titanium dioxide powder having a very fine size of nano size and hardly agglomerating with each other.

Thereafter, the dried titanium dioxide powder is suspended in a dispersion medium such as water (especially deionized water) when necessary, and used for photocatalyst etching as a colloidal solution.

In addition, the titanium dioxide-based hydrate (for example, titanium peroxo) for preparing the precursor solution is preferably prepared from an aqueous solution of titanyl chloride (TiOCl ₂ ) by the following process.

First, an aqueous solution of titanyl chloride is prepared from titanium tetrachloride (TiCl ₄ ), and a detailed method of preparation is already described in Korean Patent Application No. 2003-0035938 and Korean Patent Application No. 2004-0068654, which are the prior applications of the applicant, but are briefly described. Is as follows.

That is, to prepare a yellow and hard titanium tetrachloride as an intermediate step by dropping ice or ice water frozen in distilled water in a high purity titanium tetrachloride solution, and further water is added to melt the stable titanium transparent concentration of 1.5M or more It is prepared as an aqueous chloride solution.

The aqueous solution of titanyl chloride prepared by the above process is considerably more stable with respect to water than titanium tetrachloride, and if the concentration is 1.5M or more, no precipitation occurs even if stored for a long time. Can be stored in solution.

At this time, if the volume fraction of water and titanium tetrachloride is used as a condition for preparing the reaction starting material, the vapor pressure increases during the preparation of the aqueous solution of titanyl chloride having a concentration of titanium ions of 1.5 M or more, thereby increasing the loss of titanium tetrachloride. However, it is difficult to predict the yield of the final product, because the amount of reactant cannot be precisely controlled and the reproducibility of the preparation is poor.

Therefore, in the present invention, the amount of water added is less than the quantitative amount to proceed with the reaction to prepare a stable titanyl chloride aqueous solution as described above first, and then quantitatively analyze the concentration of titanium ions in the aqueous solution to determine the exact starting concentration By making it easy to calculate the yield, it is possible to maintain the reproducibility of the invention.

Subsequently, preparing a titanyl chloride aqueous solution of an appropriate concentration is followed based on the analyzed concentration of titanium ions. It is preferable that the concentration of said titanyl chloride in aqueous solution is 0.01-0.5M.

When the concentration of the titanyl chloride is less than 0.01M, the concentration of TiO ₂ formed from the sol through the process of titanium peroxo and TiO (OH) (OOH) is too low, making it difficult to achieve the etching effect using the photocatalyst intended in the present invention. On the contrary, when the concentration of the titanyl chloride exceeds 0.5M, the growth of particles due to nucleation during the hydrothermal reaction is actively performed, and as a result, a stable sol cannot be obtained. Therefore, the concentration of the titanyl chloride is suitably 0.01 to 0.5M.

An aqueous solution of titanyl chloride having these preferred conditions is prepared as a precipitate of titanium dioxide hydrate when mixed with a neutralizing agent. The precipitated titanium dioxide based hydrate (particularly titanium peroxo) is then washed and filtered to be used for the preparation of TiO ₂ sol.

At this time, since the titanyl chloride aqueous solution is acidic, the neutralizing agent mixed with the titanyl chloride aqueous solution is preferably used as a strong base aqueous solution, and among them, ammonia water or sodium hydroxide aqueous solution is particularly preferable.

However, as described above, in the case of the conventional TiO ₂ , the band gap energy is about 3.0 to 3.2 eV, and is irradiated to light having a short wavelength of 400 nm or less to function as a photocatalyst. Light corresponding to the above wavelength cannot be expected to be a photocatalytic effect of the TiO ₂ sol in the visible light band which is easily applicable as an ultraviolet band.

Another aspect of the present invention is to solve the problems of the prior art, and provides a method for producing a photocatalytic sol responsive in the visible light band by reducing the band gap energy of the TiO ₂ sol.

That is, in order not only to reduce the energy band gap of TiO ₂ but to have characteristics as a photocatalyst, it is preferable to substitute one or more metals which can be substituted with Ti and which can reduce the energy band gap with Ti. Transition metals are preferred as such substitutable metals, with chromium (Cr), nickel (Ni), vanadium (V), niobium (Nb) or iron (Fe) being particularly preferred.

When the metal ion is replaced with Ti, a sol having a Ti _{1 - x} M _x O (M is a metal element to be substituted) composition may be formed instead of the pure TiO ₂ used as the photocatalyst. In order to substitute the metal ions and Ti, it is necessary to add the metal ions to the appropriate one of the intermediate processes.

The present inventors have studied the proper process and method for substituting the Ti and metal ions, and it was found that the addition of the metal ions to the aqueous titanyl chloride solution was effective for ion substitution. That is, when an appropriate metal ion is added to the aqueous solution in the form of a compound to dissolve it, the metal ion in the metal compound is easily substituted with Ti in the aqueous solution.

In this case, the metal compound is preferably present in the form of chloride, nitride or hydroxide so that it can be easily dissolved in an aqueous solution of titanyl chloride. As described above, chloride, nitride or hydroxide of the transition metal is more preferable, and chromium chloride (CrCl) ₃ ), nickel chloride (NiCl ₂ ), vanadium chloride (VOCl ₅ ), niobium chloride (NbCl ₅ ) or iron chloride (FeCl ₃ ) are effective.

The concentration of the introduced metal compound is preferably 0.1 ~ 3.0% compared to the titanium ion concentration contained in the solution.

The most preferred method for producing the above-described titanium dioxide sol can be summarized as follows by sequentially combining from the first raw material. Of course, the technical idea of the present invention is based on preparing a titanium dioxide sol from a titanium dioxide-based aqueous solution as described above, and irradiating a light source by depositing an object to be etched in the titanium dioxide sol, but the most preferable method including the following pretreatment process It can be implemented more effectively by the method.

First, distilled water is added to the titanium tetrachloride stock solution to prepare an aqueous solution having a predetermined concentration or more of titanyl chloride. After diluting the aqueous titanyl chloride solution to reduce stability, a neutralizing agent is added to prepare titanium dioxide-based hydrate. The titanium dioxide based aqueous solution is then recovered through a washing and filtration step. The recovered titanium dioxide-based hydrate is added to the aqueous hydrogen peroxide solution and stirred, and then hydrothermally synthesized in an autoclave to produce a final desired titanium dioxide sol. According to the above process, titanium is present in the presence of titanium tetrachloride (TiCl ₄ ) → titanyl chloride (TiOCl ₂ ) aqueous solution → titanium dioxide hydrate (especially TiO (OH) ₂ ) → TiO (OH) (OOH) → titanium dioxide (TiO ₂ ) is converted into a sol.

Then, if necessary, as described above, after the appropriate freeze-drying process to prepare a titanium dioxide nano-powder, it may be suspended in water (especially deionized water) during etching and used for photocatalyst etching.

In this case, in order to secure the etching property in the visible light region, the compound of the transition metal may be added to the titanyl chloride aqueous solution to replace Ti with the transition metal in the added compound.

An article such as a plastic material to be etched is deposited in a titanium dioxide sol prepared under the above conditions, and then irradiated with light in a wavelength band expressing the photocatalytic properties.

The present invention will be described in more detail with reference to the following examples. However, the following examples are only for illustrating the present invention and not intended to limit the present invention, and thus the scope of the present invention is not limited by the following examples, and only the matters described in the claims and reasonably inferred therefrom. It is determined by the matter.

(Example)

Example 1

The titanium tetrachloride stock solution and distilled water were mixed to obtain an aqueous solution of titanyl chloride. In order to lower the heat of reaction resulting from this reaction, an appropriate amount of distilled water was slowly added at a temperature of about 0 ° C. to reach a titanium concentration of 4.7 M, followed by stirring to obtain a high concentration of titanyl chloride aqueous solution maintaining a stable state at room temperature.

Distilled water was added to the aqueous solution of high concentration titanyl chloride to obtain 400 cc of dilute aqueous solution of titanyl chloride having a concentration of 0.1 M of titanium ions.

A 10% aqueous ammonia solution was added to the diluted aqueous solution to cause a neutralization reaction until the pH reached 7. As a result of the neutralization reaction, a titanium dioxide hydrate precipitate was formed. The titanium dioxide hydrate precipitate was washed with distilled water five times and filtered, and then dissolved by dipping and stirring in 400 cc of 0.1 M hydrogen peroxide aqueous solution having a concentration of 10 times the titanyl chloride ion concentration.

The aqueous solution was placed in an autoclave and maintained at 60, 80, 100, 120 and 150 ° C. for 10 hours to carry out hydrothermal synthesis.

As a result, a sol in which titanium dioxide was suspended was obtained. 1 shows the results of X-ray diffraction analysis of the hydrothermally synthesized sol under reduced pressure. As a result of the X-ray diffraction analysis, it was difficult to confirm the crystallinity of the particles at 60 ° C., but it was confirmed that the anatase crystal phase was present at a temperature of 80 ° C. or higher.

In addition, when the temperature in the autoclave is 150 ℃ it could be confirmed that the particle size of the titanium dioxide is increased to cause the titanium dioxide does not exist in the sol state and precipitates occur.

Therefore, it can be confirmed that the temperature of the autoclave is 80 ~ 140 ℃ effective unless otherwise specifically controlled as the pressure of the autoclave as defined in the present invention.

2. Example 2

The titanium dioxide sol prepared in the same manner as in Example 1 was lyophilized at −60 ° C. at about 300 mtorr for about 5 hours to obtain a titanium dioxide powder. The particle size of the obtained titanium dioxide powder was 30 nm or less on a primary particle basis and 200 nm or less on a secondary particle basis. When the titanium dioxide powder is redissolved in a solvent such as water, a sol having a particle size having the same size as that of the primary particles can be obtained.

3. Example 3

After preparing 0.1M titanyl chloride aqueous solution in the same manner as in Example 1, the vanadium (V), chromium (Cr), iron (Fe), nickel (Ni) and niobium (Nb) in the 0.1M titanyl chloride aqueous solution Chloride was added at a concentration of 0.001 M to prepare 400 cc of a titanyl chloride aqueous solution in which Ti was partially substituted with the metal ion.

10% aqueous ammonia solution was added to the titanyl chloride aqueous solution and neutralized until pH 7. As a result of the neutralization reaction, a titanium dioxide hydrate precipitate was formed in the form of Ti _1-x M _x (OH) _{2 in} which part of Ti was substituted with metal ions. The titanium dioxide hydrate precipitate was washed with distilled water five times and filtered, and then dissolved by dipping and stirring in 400 cc of 1.0 M hydrogen peroxide aqueous solution, which is 10 times the titanyl chloride ion concentration.

The aqueous solution was placed in an autoclave and maintained at 120 ° C. for 10 hours to carry out hydrothermal synthesis.

The results of observing the titanium dioxide particles in the hydrothermally synthesized sol after transmission with a transmission electron microscope are shown in FIG. 2. In Figure 2 (a) is a photograph of pure titanium dioxide sol not substituted with transition metal ions, it can be seen that showing the shape of the arrowhead shape of about 20 ~ 30nm. (b) is the result of the addition of V, it can be seen that very fine particles of 5nm or less are produced. (c) is a micrograph when Cr is added, and it can be seen from the photograph that needle-shaped particles having a particle size of about 50 nm were formed. (d) was found to have a size and shape similar to that of (a) which is the result of pure titanium dioxide as a result of the addition of Fe. (e) is the case of adding Ni, which is also similar to the result of adding Fe. Finally, it was confirmed that (f) had a little less growth in the long axis direction than the case of adding Cr shown in (c) as a result of adding Nb.

3 shows the results of X-ray diffraction analysis of the hydrothermally synthesized sol under reduced pressure. (A) in Figure 3 means the analysis results for the particles when the hydrothermal synthesis temperature is set to 120 ℃ in Example 1, (b), (c), (d), (e) and (f) Shows the analysis results when V, Cr, Fe, Ni and Nb were used as substituted metal ions, respectively.

As can be seen from the above analysis results, there was a slight relative difference, but it was found that the substitution of some of Ti with metal ions did not significantly affect the crystallinity of the particles.

Figure 4 is a graph showing the average value of the particle size analysis results measured by the dynamic light scattering method (Photal Otsuka Electronics Co., Ltd. ELS 8000) 10 times for the titanium dioxide sol prepared in this Example.

From the results of FIG. 4, it was confirmed that the case of replacing with Cr had a relatively large particle size, but most of the other cases were fine crystals having a particle size of 250 nm or less. However, this method is made of a special method called light scattering method, which measures the size of particles as they pass through the path of light, so when the content of particles is high, such as the photocatalyst etching solution used in the present invention, Particles can be detected so that particles of much larger size than the actual size can be detected. In the case of the present Example, it was confirmed that the actual particle size of the sol particles is 30nm or less. This can be confirmed even if compared with the result of FIG. That is, the results of FIG. 2 are the results of observing the shape of each individual particle by transmission electron microscope, but the results of FIG. 4 are the particle size analysis by light scattering method. In this case, the particle size according to the overlap of particles during the analysis Can be observed larger.

Results of measuring zeta-potential for each particle are shown in Table 1 below.

division V addition Cr addition Fe addition Ni addition Nb addition zeta-potential -34mV +4 mV -32mV -33mV -28mV

As can be seen in Table 1, the zeta-potential of each particle except Cr was found to have excellent dispersibility as -28mV to -34mV. Therefore, the titanium dioxide sol hardly causes problems such as aggregation and precipitation even after a long time passes.

However, in case of Cr, it can be used for photocatalyst etching, and when used within a short period, it can be used without any particular problem.

4. Example 4

The titanium dioxide sol prepared in Example 3 was subjected to a light absorption test with a UV-VIS spectrometer. As shown in FIG. 5, in the case of the titanium dioxide sol not substituted with transition metal ions, light having a wavelength of less than 380 nm absorbs easily, while light absorption is rapidly decreased in a higher wavelength band. I had. Therefore, it was confirmed that the effect can be obtained only in the ultraviolet region when etching parts using pure titanium dioxide sol.

However, in the case of titanium dioxide sol in which a part of Ti is substituted with V, Cr, Fe, NI, Nb, etc., although light absorption is lower than that of pure titanium dioxide sol in the short wavelength region, pure dioxide is long in the long wavelength region. It can be seen that it has higher light absorption than titanium sol.

Accordingly, although the titanium dioxide sol substituted with the transition elements has a lower light absorption in a short wavelength region such as an ultraviolet region than a pure titanium dioxide sol, the light absorption of a long wavelength region such as a visible ray region is high, so Photocatalytic properties can be exhibited even in the presence of light.

5. Example 5

As shown in Fig. 6, a branch having a width × length × height of 5 × 5 × 8 cm is removed from (i) the titanium dioxide sol obtained in Example 1 and (ii) the titanium dioxide powder obtained in Example 2 in a quartz container excellent in light transmittance. After charging each solution suspended at a concentration of 0.005 g / l in deionized water, plastic parts were deposited in the solution to cause an etching reaction by a photocatalyst.

As a light source, a mercury short arc lamp that can irradiate light in the wavelength range of 300 ~ 500nm is used, and the intensity of light reaching the part by adjusting the distance between the part and the light source and the light source intensity is 40mW / cm ² . Adjusted. The part was etched by exposing the part and titanium dioxide sol to the light source for 15 minutes in each case.

For comparison, acid etching was performed by immersing the same plastic part in a 20% sulfuric acid solution for 15 minutes ((iii)).

The etching results in the cases (i), (ii) and (iii) are shown in FIGS. 7, 8 and 9, respectively. As can be seen from the respective figures, all showed excellent etching results. However, in the case of acid etching (FIG. 9), it can be confirmed that the etching amount is larger and the size of the etched pores is larger than the case of using titanium dioxide sol or titanium dioxide powder, which is an etching method according to the present invention. no.

That is, as described above, when the etching surface is too rough, when the pattern is subsequently formed by electroless plating, a problem arises in that the shape of the pattern becomes rough and the precision may be lowered. Looking at Figure 10 can be confirmed more reliably. That is, FIG. 10A is a photograph of a case where a copper electrode pattern is formed by patterning after electroless plating in the case of (i), and FIG. 10B is a photograph of a copper electrode pattern in the case of (iii). to be. The electroless plating process is as follows.

First, the parts were immersed in a PdCl ₂ + SnCl ₂ + 30% HCl solution for 15 minutes to adsorb Pd particles, which serve as catalysts in the electroless plating, to the surface of the specimen, and then H to activate the adsorbed Pd particles. _It was immersed in ₂ SO ₄ solution for 5 minutes.

Thereafter, the parts were subjected to electroless copper plating. Ferring liquid was used as a plating liquid, and formaldehyde was used as a reducing agent.

The plating solution was maintained at 55 ~ 60 ℃ and the specimen was deposited for 3 minutes. 2,2-bipyridyl and NaCN were used as stabilizers to prevent sudden precipitation of copper, and a small amount of surfactant was added to improve the properties of the copper film. At this time, the pH of the plating liquid was adjusted with a sodium hydroxide solution.

Patterning was performed on the plating layer to form a pattern of electrodes.

As can be seen from the results of FIGS. 10A and 10B, when the pattern is formed on the part surface of (i), which is a result of photocatalytic etching with a titanium dioxide sol, the pattern is formed on the part of (iii), which is a result of acid etching. A much smoother and cleaner pattern surface was obtained.

Therefore, the advantageous effect of the photocatalyst etching method by this invention was confirmed.

6. Example 6

In order to investigate the effect of the photocatalyst including the brookite phase, a brookite phase titanium dioxide sol was prepared by the following method.

Titanium dioxide hydrate was obtained in the same manner as in Example 1. The titanium dioxide hydrate was immersed and stirred in an aqueous hydrogen peroxide solution under the same conditions as in Example 1.

The dissolved aqueous solution was hydrothermally synthesized at 120 ° C. for 10 hours while maintaining the internal pressure of the autoclave at 40 bar using nitrogen, argon, compressed air, or the like to obtain a titanium dioxide sol containing a large amount of brookite phase.

As a result of observing the monodispersed spheres of the obtained titanium dioxide with a transmission electron microscope, all the primary particles of 30 nm or less were observed, and particles having a more spherical shape than the particles obtained in Example 1 were observed. As a result of the X-ray diffraction test on the particles, as shown in FIG. 11, it was confirmed that the crystalline phase of the particles contained a large amount of brookite phase.

In addition, the results of the UV-VIS spectrum analysis of the titanium dioxide sol obtained in this example showed that light absorption occurs in a relatively long wavelength region as compared to the titanium dioxide sol on the anatase (when treated at 120 ° C. in Example 1). there was.

In addition, as a result of photocatalyst etching using the titanium dioxide sol on the brookite, an etching surface having a level similar to that of FIG. 7 was obtained even at a very low luminous intensity of 10 mW / cm ² .

Thus, the beneficial effect of the Brookkite phase could be confirmed.

As described above, according to the present invention, by using a titanium dioxide sol as a photocatalyst, a component having an etching surface having an appropriate roughness can be produced, which is effective for electroless plating.

In addition, the present invention can provide a photocatalyst etching method that is responsive to not only ultraviolet light but also visible light by replacing some of Ti with transition metal ions.

Finally, another effect of the present invention is to provide a method for photocatalyst etching using a brookite phase having excellent dispersibility and excellent photocatalytic efficiency.

Claims (22)

delete Immersing the plastic part in a colloidal solution in which nano-sized titanium dioxide is suspended in a sol state; And Irradiating a light source to the immersed plastic part; As an etching method for electroless plating consisting of, The titanium dioxide sol, Neutralizing by mixing a neutralizing agent with an aqueous solution of titanyl chloride to obtain titanium dioxide-based hydrate; Washing and filtering the titanium dioxide based hydrate; Immersing and dissolving the titanium dioxide-based hydrate in an aqueous solution in which a hydrogen peroxide of 8 to 10 times the number of moles of titanyl chloride ion is dissolved; And Comprising the titanium dioxide-based hydrate is dissolved in the aqueous hydrogen peroxide solution into an autoclave and hydrothermally synthesized to obtain a titanium dioxide-based sol An etching method for electroless plating, which is prepared by a titanium dioxide sol process. The method of claim 2, wherein the aqueous titanyl chloride solution is prepared by dropping ice or ice water frozen in distilled water into the titanium tetrachloride stock solution to prepare yellow and hard titanium tetrachloride as an intermediate step, and then adding and dissolving water to the titanium ion concentration to 1.5. Etching method for electroless plating, characterized in that the production to be M or more. The etching method of claim 2, wherein the temperature in the autoclave is 80 to 140 ° C. The method of claim 4, wherein the temperature in the autoclave is 110 ~ 130 ℃. The method of claim 2, wherein the temperature in the autoclave is 80 to 180 ° C. when the pressure in the autoclave is adjusted to 30 to 100 bar. The etching method for electroless plating according to any one of claims 4 to 6, wherein the time of hydrothermal synthesis in the autoclave is 3 to 24 hours. The method of claim 2, wherein before the neutralizing agent is mixed with the aqueous titanyl chloride solution, one or two or more transition metal compounds of a transition metal compound including a transition metal element substituted with titanium of the aqueous titanyl chloride solution, a nitride, and a hydrate. Etching method for electroless plating, characterized in that the addition. The etching method of claim 8, wherein the transition metal comprises one selected from chromium (Cr), nickel (Ni), vanadium (V), niobium (Nb), or iron (Fe). Way. The method of claim 2, wherein the intensity of light irradiated to the component in the step of irradiating the light source is 3 ~ 60mW / cm ² Etching method for electroless plating. The etching method of claim 2, wherein the pressure in the autoclave is controlled to 35 to 100 bar and the temperature is maintained to 80 to 180 ° C for at least 7 hours. delete Preparing a colloidal solution in which titanium dioxide is suspended in a sol state by suspending titanium dioxide nano powder having a size of primary particles of 30 nm or less in water; Dipping a plastic part in a colloidal solution in which the titanium dioxide is suspended in a sol state; And Irradiating a light source to the immersed plastic part; As an etching method for electroless plating consisting of, The nano-sized titanium dioxide powder, Neutralizing by mixing a neutralizing agent with an aqueous solution of titanyl chloride to obtain titanium dioxide-based hydrate; Washing and filtering the titanium dioxide based hydrate; Immersing and dissolving the titanium dioxide-based hydrate in an aqueous solution in which a hydrogen peroxide of 8 to 10 times the number of moles of titanyl chloride ion is dissolved; Obtaining a titanium dioxide sol by hydrothermally synthesizing a solution in which the titanium dioxide-based hydrate is dissolved in the aqueous hydrogen peroxide solution in an autoclave; And Lyophilizing the titanium dioxide sol; Etching method for electroless plating, characterized in that produced by the titanium dioxide powder manufacturing process consisting of. The etching method of claim 13, wherein the freeze drying is performed under a vacuum of 300 mtorr or less in a temperature range of -40 to -60 ° C. The method of claim 13, wherein the titanyl chloride solution is prepared by dropping ice or ice water frozen in distilled water into titanium tetrachloride stock solution to prepare yellow and hard titanium tetrachloride as an intermediate step. Etching method for electroless plating, characterized in that the production to be M or more. The method of claim 13, wherein the temperature in the autoclave is 80 ~ 140 ℃. The method of claim 16, wherein the temperature in the autoclave is 110 ~ 130 ℃. 15. The method of claim 13, wherein the temperature in the autoclave is 80 ~ 180 ℃ when the pressure in the autoclave is adjusted to 30 ~ 100bar. The etching method for electroless plating according to any one of claims 16 to 18, wherein the time of hydrothermal synthesis in the autoclave is 3 to 24 hours. The method of claim 13, prior to mixing the neutralizing agent in the aqueous solution of titanyl chloride, one or two or more transition metal compounds of the transition metal compound, nitride, hydrate of the transition metal containing a transition metal element substituted with titanium of the aqueous titanyl chloride solution Etching method for electroless plating, characterized in that the addition. The method of claim 20, wherein the transition metal is selected from chromium (Cr), nickel (Ni), vanadium (V), niobium (Nb), or iron (Fe). Etching method. 15. The method of claim 13, wherein the intensity of light irradiated to the component in the step of irradiating the light source is 3 ~ 60mW / cm ² Etching method for electroless plating.

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