TWI679316B - Titanium cathode surface modification method for electroplating low-roughness copper foil - Google Patents

Abstract

A method for modifying the surface of a titanium cathode for electroplating a low-roughness copper foil includes the following steps. A titanium cathode is provided. The surface of the titanium cathode may be unmodified, chemically modified, or physically modified. Step two, a conductive layer is deposited on the surface of the titanium cathode through an electroplating step; step three, the conductive layer is subjected to an etching step to form an etching film; step four, a conductive layer is precipitated on the surface of the etching film through an electroplating step ; Step five, repeat steps three and four at least once. The method of the present invention can obtain a titanium cathode with a significantly improved surface brightness and a significantly reduced roughness, and a copper foil having a smooth surface and low roughness can be electroplated.

Description

Titanium cathode surface modification method for plating low-roughness copper foil

The present invention relates to an electroplating device for electroplating a copper foil. More specifically, the present invention relates to a surface modification method of a titanium cathode of the electroplating device. By the method of the present invention, a titanium cathode with improved surface brightness and reduced roughness is obtained, and a copper foil with a low roughness can be electroplated and deposited with a smooth surface.

Titanium cathode electrodes are widely used in the manufacture of electroplated copper foil. A copper foil is obtained by depositing a thin copper layer on the surface of the titanium cathode by a plating process in a plating apparatus and peeling it off. The side of the green copper foil that is in close contact with the titanium cathode is called the smooth side (S-side), and the other side is called the rough or matte side (M-side). The Japanese JIS standard stipulates that the surface roughness Ra value of the smooth surface of the electroplated copper foil should be 0.4 μm or less.

The surface of the titanium cathode will be roughened and titanium dioxide formed due to long-term electroplated copper foil process and oxidation. Once the surface of the titanium cathode becomes rough, the smooth surface of the electroplated copper foil also becomes rough. Titanium dioxide shields the exposed area of pure conductive titanium on the cathode, weakening the conductivity of the titanium cathode and making the conductivity non-uniform. Therefore, the rough surface of the electroplated green copper foil forms coarse copper particles and becomes rough. Such changes are not allowed. As long as the Ra value of the electroplated copper foil exceeds a predetermined management value, the surface of the titanium cathode needs to be polished (commonly referred to as titanium cathode maintenance). In addition to flattening the unevenness of the surface of the titanium cathode, the conductivity is also poor. The titanium dioxide layer was polished away to expose the pure titanium layer with better conductivity.

However, the surface polishing and maintenance of the titanium cathode cannot guarantee the smooth surface of the plated green copper foil. The surface roughness can reach the expected standard (such as the aforementioned Ra value should be less than 0.4 μm), so the smooth surface of the green copper foil must be subjected to other surface treatment procedures to reduce its surface roughness.

The invention provides a method for surface modification of a titanium cathode.

A method for modifying the surface of a titanium cathode for electroplating a low-roughness copper foil includes the following steps. A titanium cathode is provided. The surface of the titanium cathode may be unmodified, chemically modified, or physically modified. Step two, a conductive layer is deposited on the surface of the titanium cathode through an electroplating step; step three, the conductive layer is subjected to an etching step to form an etching film; the etching step is an immersion of an acid etching solution, the pH of the acid etching solution:- 0.20 ~ 1.30, immersion time is 5 ~ 30 minutes; step four, a conductive layer is deposited on the surface of the etching film through a plating step; step four is the same as step two; step five, repeat steps three and Step four at least once.

Efficacy of the present invention: The method of the present invention can obtain a titanium cathode with a significantly improved surface brightness and a significantly reduced roughness, and can produce a copper foil with a low roughness on the electroplated surface.

The invention can be realized on titanium cathodes whose surface is not modified, chemically modified, or physically modified, all of which have the effects of significantly improving surface brightness and reducing roughness.

In the preferred embodiment of the present invention, a total of three conductive plating (copper layer) and two etching steps are performed on the surface of the titanium cathode. The obtained surface roughness data shows that each time the titanium cathode is significantly reduced. Surface roughness. It is logically speculated that the surface roughness of the titanium cathode can be further reduced by implementing more conductive plating (copper layer) and etching steps. According to the needs of the industry Select an appropriate number of times to control the surface roughness of the titanium cathode to obtain a low-roughness copper foil that meets the industry requirements.

First image, a surface image of the titanium cathode according to the first embodiment of the present invention, a is a surface image of the titanium cathode after the step 2 of the present invention, and b is a surface view of the titanium cathode after the steps 2, 3, and 4 of the present invention Image; c is the surface image of the titanium cathode after the steps 2, 3, 4 and 5 of the present invention.

The second figure shows the brightness value of the titanium cathode surface modified by the method of the first embodiment of the present invention.

The third figure is a 1000-times SEM image of the titanium cathode surface modified by the method of the second embodiment of the present invention.

The fourth figure shows the surface roughness (Ra) value of titanium cathode modified by the method of the second embodiment of the present invention.

First embodiment

The titanium cathode surface modification method of the invention comprises:

Step 1: The surface of the titanium cathode is contacted with a strong acid liquid with a pH value of <0 or a pH value of 0 to 4 after 14 to 28 hours to take it out and dry it. The surface of the titanium cathode is a chemically modified surface; the strong acid liquid used in this step Piranha Solution.

In step two, a chemically modified surface of the titanium cathode precipitates a conductive layer through a plating step; the conductive layer is a copper layer.

The composition of the plating solution used in this plating step includes a soluble copper salt, a pH adjuster, and an additive. The soluble copper salt is preferably a copper sulfate pentahydrate, 145 g / L to 250 g / L, and preferably 220 g / L. The pH adjuster includes, but is not limited to, nitric acid, hydrochloric acid, sulfuric acid, and phosphoric acid; sulfuric acid is preferred; the concentration is 3% to 10% (V / V); and the pH is -0.20 to 1.30. Additives: Contains chloride ions, Accelerators, levelers, inhibitors. Among them, the chloride ion concentration is 5 to 50 ppm, and preferably 10 ppm. The accelerator is selected from thiol compounds, including but not limited to SPS (sodium dithiodipropane sulfonate), MPS (sodium 3-mercapto-1-propane sulfonate), DPS (N, N-dimethyl-di- Alternatives to sodium thiocarbonylpropane sulfonate), ZPS (3- (benzothiothiazol-2-mercapto) -sodium propane sulfonate), UPS (thioureapropyl sulfate); concentration is 50 ~ 150ppm, preferably 100ppm. The leveling agent is selected from organic nitrogen-containing heterocyclic compounds, including but not limited to JGB (Janus Green B), DB (Diazine Black), MV (Methylene Violet 3RAX), SO (Safranine O), ABPV (Alcian Blue Pyridine Variant), and BTA (Benzotriazole) at a concentration of 5 to 100 ppm, preferably 10 ppm. The inhibitor is selected from polyethylene glycol (Polyethlene glycol, PEG), the molecular weight is 3000-12000, and the concentration is 50-300ppm, preferably 200ppm.

An insoluble anode is used in the electroplating step, and the material may be platinum, iridium oxide / titanium, iridium oxide / tantalum pentoxide / titanium. The bath temperature is 25 to 65 ° C, preferably 30 to 40 ° C. Current density: 30 ~ 50ASD. The copper liquid needs to be stirred, including but not limited to air stirring, motor jet stirring, blade stirring, magnet stirring, and the like.

In step three, the conductive layer (copper layer) is subjected to an etching step to form an etching film. The etching step is an immersion of an acid etching solution. Acid etching liquid is a mixture of acidic liquid and hydrogen peroxide solution; acidic liquid is one of sulfuric acid, nitric acid, phosphoric acid and aqua regia. The mixing ratio of acidic liquid and hydrogen peroxide solution is 1: 1 ~ 4: 1, pH value of acid etching liquid: -0.20 ~ 1.30, temperature: 25 ℃ ~ 45 ℃, soak for about 5 ~ 30 minutes.

In step 4, a conductive layer is deposited on the surface of the etching film through a plating step; the plating step in step 4 is the same as the plating step in step 2; and step 5 is repeated at least once in steps 3 and 4.

Titanium cathode brightness measurement (1)

As shown in the first figure, a, b, and c are three titanium cathodes in the figure, a is an image of the surface of the titanium cathode after the steps 1 and 2 of the present invention; b is the surface of the titanium cathode after the steps 1 to 4 of the present invention; c is Surface images of the titanium cathode after steps 1 to 5 of the present invention. A, b, and c all measure the surface brightness with a brightness meter, among which a surface brightness is 5.1 to 7.8, b surface brightness is 100 to 146, and c surface brightness is 120 to 177. As can be seen from the figure, the surface a has a low brightness without any reflected light and shadow. b The surface has a high brightness, with slightly reflected light and shadow in the lower right. c. The surface has high brightness, and there is obvious reflected light and shadow below. It can be proved from the first figure that steps 2 to 5 of the present invention specifically increase the surface brightness of the titanium cathode.

Titanium cathode brightness measurement (2)

The surface of the titanium cathode modified by the method of the first embodiment is subjected to a brightness test with a brightness meter, and the measured light reflection amount represents a brightness value. As shown in the second figure, there are four titanium cathodes A, B, C, and D. Among them, A, B, C, and D are all prepared by the method of the first embodiment of the present invention, but A, B, C, and D. D. Soaking time of strong acid liquid is different. A was not soaked with a strong acid liquid, B was soaked for 7 hours, C was soaked for 14 hours, and D was soaked for 28 hours. In terms of brightness performance, the surface brightness of C and D titanium cathodes are 217, 505, and the surface brightness of A, B are 64, 55, respectively. The surface brightness of C and D titanium cathodes was significantly improved. In the second figure, four titanium cathodes A1, B1, C1, and D1 are used as a comparison. None of the four titanium cathodes has undergone the modification method of the first embodiment of the present invention. Based on comparison considerations, A1, B1, C1, D1 and A, B, C, and D were all measured for brightness at 0, 7, 14, and 28 hours. Among them, the surface brightness of C1 and D1 is 24 and 59, which is much lower than that of C and D titanium cathodes. It can be proved that the method of the present invention does improve the surface brightness of the titanium cathode.

The brightness of this embodiment is used as an index for evaluating the surface roughness of the titanium cathode. It is common knowledge that when the surface roughness is large, the amount of light reflection decreases, so the brightness value decreases; conversely, when the surface roughness is smaller, the surface is more inclined With smoothing, the amount of light reflection increases and the brightness value increases. From the first The experimental results in a figure can prove that the surface brightness of the titanium cathode is significantly improved by the modification method of the present invention, which means that the surface roughness of the titanium cathode is significantly reduced. When the surface roughness of the titanium cathode is reduced, the surface roughness of the green copper foil precipitated therefrom is also reduced, which is beneficial to the production of green copper foil with a smooth surface (S surface) having a low roughness.

Second embodiment

The titanium cathode surface modification method of the invention comprises:

In step one, the surface of the titanium cathode is polished with sandpaper having a roughness of at least 1000, so that the surface of the titanium cathode becomes a physically modified surface.

In step two, a physically modified surface of the titanium cathode undergoes an electroplating step to precipitate a conductive layer; the conductive layer is a copper layer.

The composition of the plating solution used in this plating step includes a soluble copper salt, a pH adjuster, and an additive. The soluble copper salt is preferably a copper sulfate pentahydrate, 145 g / L to 250 g / L, and preferably 220 g / L. The pH adjuster includes, but is not limited to, nitric acid, hydrochloric acid, sulfuric acid, and phosphoric acid; sulfuric acid is preferred; the concentration is 3% to 10% (V / V); and the pH is -0.20 to 1.30. Additives: Contains chloride ions, accelerators, levelling agents, inhibitors. Among them, the chloride ion concentration is 5 to 50 ppm, and preferably 10 ppm. The accelerator is selected from thiol compounds, including but not limited to SPS (sodium dithiodipropane sulfonate), MPS (sodium 3-mercapto-1-propane sulfonate), DPS (N, N-dimethyl-di- Alternatives to sodium thiocarbonylpropane sulfonate), ZPS (3- (benzothiothiazol-2-mercapto) -sodium propane sulfonate), UPS (thioureapropyl sulfate); concentration is 50-150ppm, preferably 100ppm. The leveling agent is selected from organic nitrogen-containing heterocyclic compounds, including but not limited to JGB (Janus Green B), DB (Diazine Black), MV (Methylene Violet 3RAX), SO (Safranine O), ABPV (Alcian Blue Pyridine Variant), and BTA (Benzotriazole) at a concentration of 5 to 100 ppm, preferably 10 ppm. Inhibitor selected from polyethylene glycol (Polyethlene glycol, PEG), molecular weight 3000 ~ 12000, concentration 50 ~ 300ppm, preferably 200ppm.

An insoluble anode is used in the electroplating step, and the material may be platinum, iridium oxide / titanium, iridium oxide / tantalum pentoxide / titanium. The bath temperature is 25 to 65 ° C, preferably 30 to 40 ° C. Current density: 30 ~ 50ASD. The copper liquid needs to be stirred, including but not limited to air stirring, motor jet stirring, and blade stirring.

In step three, the conductive layer (copper layer) is subjected to an etching step to form an etching film. The etching step is an immersion of an acid etching solution. Acid etching liquid is a mixture of acidic liquid and hydrogen peroxide solution; acidic liquid is one of sulfuric acid, nitric acid, phosphoric acid and aqua regia. The mixing ratio of acidic liquid and hydrogen peroxide solution is 1: 1 ~ 4: 1. 1.30, temperature: 25 ℃ ~ 45 ℃, soak for about 5 ~ 30 minutes.

In step 4, a conductive layer is deposited on the surface of the etching film through a plating step; the plating step in step 4 is the same as the plating step in step 2; and step 5 is repeated at least once in steps 3 and 4.

Surface roughness measurement of titanium cathode

The third figure is a 1000-times SEM image of the titanium cathode surface modified by the method of the second embodiment. The fourth figure shows the surface roughness (Ra) value of the surface of the titanium cathode modified by the method of the second embodiment measured by a roughness meter.

In the third figure, group W is the original titanium cathode that has not been chemically or physically modified. The conductive layer (copper layer) has been plated three times. Groups X, Y, and Z are titanium cathodes whose surfaces are polished with sandpaper with a roughness of 180, 1000, and 2500, respectively After that, the conductive layer (copper layer) was plated three times.

With the third and fourth figures, the description is as follows: Group W: The first Ra-plated conductive layer (copper layer) of W1 is 0.862. The Ra value of the second conductive layer (copper layer) of W2 was 0.613. The Ra value of the third conductive plating layer (copper layer) of W3 was 0.412.

Group X: The Ra value of the first conductive layer (copper layer) of X1 is 0.773. The Ra value of the second conductive layer (copper layer) of X2 was 0.652. The Ra value of the third conductive plating layer (copper layer) of X3 was 0.449.

Group Y: The Ra value of the first conductive layer (copper layer) of Y1 is 0.558. The Ra value of the second conductive layer (copper layer) of Y2 was 0.249. The third Ra plating value (copper layer) of Y3 was 0.198.

Group Z: The Ra value of the first conductive layer (copper layer) of Z1 is 0.417. The Ra value of the second conductive layer (copper layer) of Z2 was 0.225. The Z3 third plating of the conductive layer (copper layer) has a Ra value of 0.169.

It can be known from the above-mentioned W group that steps 2 to 5 of the present invention are implemented on the surface of the titanium cathode without physical or chemical modification, and still have the function of significantly reducing the surface roughness of the titanium cathode.

From the Ra measurement results of the X, Y, and Z groups, it can be seen that the surface roughness of the titanium cathode modified by the method of the second embodiment of the present invention is significantly reduced. Especially for groups Y and Z, when the surface of the titanium cathode is polished finer by the physical modification method, and then the steps 2 to 5 of the present invention are continuously applied, a titanium cathode with a lower surface roughness can be obtained. The surface roughness of the titanium cathode is reduced, and the surface roughness of the green copper foil precipitated therefrom is also reduced, which is conducive to the production of a green copper foil with a smooth surface (S surface) having a low roughness.

As can be further seen from the fourth figure, the second embodiment of the present invention has performed a total of three conductive plating (copper layer) and two etching steps on the titanium cathode surface from step two to step five, each time significantly reducing the titanium cathode. Surface roughness. It is logically speculated that the surface roughness of the titanium cathode can be further reduced by implementing more conductive plating (copper layer) and etching steps. The appropriate number of times can be selected according to the needs of the industry, and the surface roughness of the titanium cathode can be controlled to obtain a low-roughness copper foil that meets the requirements of the industry.

Claims (3)

A method for modifying the surface of a titanium cathode for electroplating a low-roughness copper foil includes the following steps: Step 1. The surface of the titanium cathode is contacted with a strong acid liquid having a pH value of less than 0 or 0 to 4 after 14 to 28 hours to remove and dry the surface of the titanium cathode. Is a chemically modified surface; step two, a chemically modified surface of the titanium cathode precipitates a conductive layer through an electroplating step; the conductive layer is a copper layer; step three, the conductive layer is subjected to an etching step to become an etch Film; the etching step is to immerse the acid etching solution, the pH value of the acid etching solution is -0.20 to 1.30, and the immersion time is 5 to 30 minutes; the acid etching solution is a mixture of an acidic liquid and a hydrogen peroxide solution; the acidic liquid is sulfuric acid, nitric acid, One of phosphoric acid and aqua regia, the mixing ratio of the acidic liquid and the hydrogen peroxide solution is 1: 1 to 4: 1, and the temperature is 25 ° C to 45 ° C. Step four, the surface of the etching film is subjected to an electroplating step to precipitate a conductive layer; the conductive layer is Copper layer; The plating step in step 4 is the same as the plating step in step 2. Step 5, repeat steps 3 and 4 at least once. The plating solution used in the plating steps in steps 2 and 4 contains soluble copper salt and pH. Tune Agent and additive; soluble copper salt is preferably copper sulfate pentahydrate 145g / L ~ 250g / L; pH adjuster is selected from nitric acid, hydrochloric acid, sulfuric acid, phosphoric acid, and the concentration is 3% ~ 10% (V / V); pH value is -0.20 ~ 1.30; additives include chloride ion, accelerator, leveler, and inhibitor; chloride ion concentration is 5 ~ 50ppm, accelerator is selected from thiol compounds, concentration is 50 ~ 150ppm; leveling The agent is selected from organic nitrogen-containing heterocyclic compounds at a concentration of 5 to 100 ppm; the inhibitor is selected from polyethylene glycol at a concentration of 50 to 300 ppm; an insoluble anode is used in this plating step, the bath temperature is 25 to 65 ° C, and the current density 30 ~ 50ASD, stir copper solution. A method for modifying the surface of a titanium cathode for electroplating a low-roughness copper foil includes the following steps. The titanium cathode surface is polished with sandpaper having a roughness of at least 1000, so that the surface of the titanium cathode becomes a physically modified surface. Step two: titanium The conductively modified surface of the cathode precipitates a conductive layer through an electroplating step; the conductive layer is a copper layer; step three, the conductive layer is subjected to an etching step to form an etching film; the etching step is an immersion of an acid etching solution, acid Etching solution pH: -0.20 ~ 1.30, soaking time is 5 ~ 30 minutes; the acid etching solution is a mixture of acidic liquid and hydrogen peroxide solution; the acidic liquid is one of sulfuric acid, nitric acid, phosphoric acid and aqua regia; The ratio is 1: 1 to 4: 1, and the temperature is 25 ° C to 45 ° C. Step 4, the surface of the etching film is subjected to a plating step to precipitate a conductive layer; the conductive layer is a copper layer; The plating steps are the same; step 5, repeat steps 3 and 4 at least once; the composition of the plating solution used in the plating steps of steps 2 and 4 includes soluble copper salt, pH adjuster, and additives; The soluble copper salt is preferably copper sulfate pentahydrate 145g / L ~ 250g / L; the pH adjuster is selected from nitric acid, hydrochloric acid, sulfuric acid, and phosphoric acid, and the concentration is 3% to 10% (V / V); pH value It is -0.20 ~ 1.30; the additives include chloride ion, accelerator, leveler, and inhibitor; the chloride ion concentration is 5-50ppm, the accelerator is selected from thiol compounds, and the concentration is 50 ~ 150ppm; the leveler is selected from organic ingredients A nitrogen heterocyclic compound with a concentration of 5 to 100 ppm; the inhibitor is selected from polyethylene glycol with a concentration of 50 to 300 ppm; an insoluble anode is used in this plating step, the bath temperature is 25 to 65 ° C, the current density is 30 to 50 ASD, copper Liquid stirring. A titanium cathode surface modification method for electroplating a low-roughness copper foil includes the following steps: preparing a titanium cathode without chemical or physical modification on the surface; and step two, depositing a conductive layer on the surface of the titanium cathode through a plating step The conductive layer is a copper layer; step three, the conductive layer is subjected to an etching step to form an etching film; the etching step is an immersion acid etching solution, the pH value of the acid etching solution is -0.20 to 1.30, and the immersion time is 5 to 30 minutes; the acid etching solution is a mixture of acidic liquid and hydrogen peroxide solution; the acidic liquid is one of sulfuric acid, nitric acid, phosphoric acid and aqua regia; the mixing ratio of acidic liquid and hydrogen peroxide solution is 1: 1 ~ 4: 1, temperature is 25 ℃ ~ 45 ℃; step four, a conductive layer is deposited on the surface of the etching film through a plating step; the conductive layer is a copper layer; the plating step of step four is the same as the plating step of step two; step five, repeating steps three and four at least Once; the composition of the plating solution used in the plating steps of steps 2 and 4 includes a soluble copper salt, a pH adjusting agent, and an additive; the soluble copper salt is preferably a copper sulfate pentahydrate 145 g / L to 250 g / L; a pH adjusting agent It is selected from the group consisting of nitric acid, hydrochloric acid, sulfuric acid, and phosphoric acid with a concentration of 3% to 10% (V / V); the pH value is -0.20 to 1.30; the additives include chloride ion, accelerator, leveler, and inhibitor; The chloride ion concentration is 5 ~ 50ppm, the accelerator is selected from thiol compounds and the concentration is 50 ~ 150ppm; the leveling agent is selected from organic nitrogen-containing heterocyclic compounds, the concentration is 5 ~ 100ppm; the inhibitor is selected from polyethylene glycol, the concentration 50 ~ 300ppm; insoluble anode is used in this electroplating step, bath temperature is 25 ~ 65 ℃, current density is 30 ~ 50ASD, copper bath is stirred.