JP2004307991A - Copper plating hardness maintaining agent and copper plating method, and gravure plate and lens die using the method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a copper plating hardness maintaining agent which can form a copper plating film having excellent hardness, brightness, and leveling property, excellent machinability, and good working stability, and can maintain the hardness of the plating film without degradation for a long period of time, and to provide a method for copper plating, and a gravure plate and lens die made by using the copper plating method. <P>SOLUTION: The copper plating method comprises using a plating liquid of 20 to 80 ppm in the concentration of a nitrogen-containing polymeric compound as the copper plating hardness maintaining agent and forming the copper plating layer on the surface by energizing an object to be plated. The gravure plate and the lens die are formed by using such copper plating method. Also, the concentration of the nitrogen-containing polymeric compound is preferably 60 to 80 ppm. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to a copper plating technology, and more particularly, to a hardness of a plating film which is excellent in hardness, glossiness, leveling property, and which can form a copper plating film layer having excellent machinability and excellent processing stability. The present invention relates to a copper plating hardness maintenance agent and a copper plating method capable of maintaining the copper plating temperature for a long time without lowering, and a gravure plate and a lens mold produced by using the copper plating method.

  In order to obtain a bright copper plating film, a combination of organic compounds such as organic thio compounds, oxygen-containing polymer compounds, and organic acid amides has been added as a copper plating additive. These additives are consumed by electrolysis and are generally replenished in proportion to the amount of electricity passed.

Patent Literature 1 is shown below.
For example, in order to realize good uniform electrodeposition of copper plating on a printed circuit board having through holes and stabilize the life of a plating solution for a long period of time, the additive concentration is measured by the CVS method (Cyclic Voltammetric). Stripping). (See Patent Document 1) In the production of the gravure plate, nickel plating or copper cyanide plating is applied on the core of an iron cylinder, and copper sulfate plating is electrodeposited thereon. Thereafter, the copper plating is polished to expose a flat surface, and a layer to be subjected to a peeling treatment and further engraving or etching is electrolytically applied from a copper sulfate plating bath containing an additive. In general, various additives are added to the copper plating on the processed surface in order to improve the machinability with a diamond needle.

  Conventionally, an organic compound such as a thiourea derivative or a dye has been added as a hardness maintaining agent as an additive for the copper sulfate plating.

  When a dye-based organic compound has been used for many years, a large amount of decomposed products is accumulated in a plating tank, and it is difficult to stably maintain the composition. In addition, it is seen that the hardness is remarkably reduced by storage, although an appropriate amount is added.

  In the case of performing copper plating, in addition to a hardness maintaining agent, a plating agent is added by adding a brightening agent for providing surface gloss, an inhibitor for preventing burning, and a leveling agent for improving leveling properties. When a thiourea-based organic compound derivative is used as a hardness maintaining agent, it may be used alone or in combination with a brightener, an inhibitor, and a leveling agent. However, when used alone, the properties of the thiourea-based organic compound derivative in the plating solution are not clearly understood, and it has been difficult to maintain by analysis. In addition, when a dye-based organic compound is added and used for many years, decomposition products are accumulated in the plating tank, and it is difficult to maintain and maintain the composition stably, and an additive that does not generate decomposition products as much as possible is desired. Was.

A gravure plate, a lens mold using the gravure plate, or a Fresnel mold prepared by cutting a flat plate is added with a hardening agent to improve machinability, and is maintained in a Vickers hardness Hv 190 to 220. In order to increase the hardness, a thiourea derivative may be added alone as a curing agent.

  However, when a curing agent is added to a plating solution in combination with a brightener, an inhibitor, and a leveling agent, the CVS method cannot eliminate the influence of other components and cannot analyze and control these components. Although it was possible only with a visual test such as Hull cell, it was not possible to perform detailed management by numerical management.

Patent Document 2 is shown below.
JP, 2000-146586, A There is an example in which a good copper plating layer is obtained, for example, when the concentration of a sulfur compound in a plating solution is controlled and maintained at 20 to 60 mg / L using an ICP emission spectrometer. . (Patent Document 2) However, in particular, when producing a gravure plate or a lens mold using a copper plating method, it is not sufficient to control only the sulfur compound concentration in the plating solution, and the hardness of the gravure plate changes with time. This caused the stylus needle to be broken, and the processing after plating was not stable. When cutting the lens mold, there were cases where the lenticular lens could not be cut well because the shape of the lenticular lens was different from the design value. Further, in the manufacture of the Fresnel lens mold, there is a problem that, if the additive management is not properly added, burrs are generated and defects such as breakage during cutting of the cutting tool are generated.

  The present invention has been made in order to solve the above-mentioned problems, and although the hardness changes depending on the amount of the hardness maintenance agent added, the decomposition products thereof can be used as little as possible and can be used stably. Then, the hardness of the copper plating film does not change for several years, and when the gravure plate is manufactured by processing the gravure plate cylinder with an engraving machine, it is difficult for the stylus needle to be broken, or in the Fresnel lens mold, the tip of the mold hill is dripped. A copper plating method capable of forming a copper plating film layer having excellent hardness, glossiness, leveling property, and excellent machinability and excellent processing stability; An object of the present invention is to provide a gravure plate and a lens mold manufactured by using the method.

  The inventors are not enough to manage the concentration of the organic sulfur compound alone, but pay attention to the concentration of a hardness maintenance agent composed of an organic nitrogen-containing polymer compound that can serve as a curing agent, and appropriately manage the concentration, and determine the hardness, gloss, The present inventors have discovered that a copper plating film having good leveling property and good processing stability can be formed, and the present invention has been accomplished.

  That is, the invention according to claim 1 is a copper plating comprising, in electrolytic copper plating, an organic polymer compound added to a plating solution capable of maintaining a plated film hardness without decreasing over a long period of time. It is a hardness maintenance agent.

  The invention according to claim 2 is the copper plating hardness maintenance agent according to claim 1, wherein the organic polymer compound contains a nitrogen atom in a structural formula.

Further, the invention according to claim 3 is characterized in that a copper plating layer is formed on the surface by applying a current to an object to be plated using a plating solution having a concentration of the organic polymer compound of 20 to 80 ppm. Copper plating method.

  The invention according to claim 4 is the copper plating method according to claim 3, wherein the concentration of the organic polymer compound is 60 to 80 ppm.

  The invention according to claim 5 is the copper plating method according to claim 3 or 4, wherein the concentration of the nitrogen-containing polymer compound is maintained and a plating layer is formed on the surface of the object to be plated. It is.

  The invention according to claim 6 is a gravure plate characterized by using the copper plating method according to any one of claims 3 to 5.

  According to a seventh aspect of the present invention, a copper cutting layer is provided on a metal plate using the copper plating method according to any one of the third to fifth aspects, and the cutting layer has a shape opposite to the lens pattern shape. A lens mold formed by cutting a mold.

  The invention according to claim 8 is the lens mold according to claim 7, wherein the lens pattern is any one of a lenticular lens, a Fresnel lens, a micro lens, and a prism lens.

  The invention according to claim 9 is characterized in that the surface of the lens mold is plated with any one of ultra-thin chromium plating, electroless nickel plating, or electrolytic nickel plating. 9. A lens mold according to item 8.

  According to the present invention, the copper plating hardness maintenance agent is a non-dye-based compound, the accumulation of decomposition products is small even when used for a long time, and a copper film having a desired hardness can be obtained without a long-term decrease in hardness when a predetermined amount is added. As a result, a good gravure plate or Fresnel lens mold can be stably manufactured. By controlling the concentration of the nitrogen-containing polymer compound as a hardness maintenance agent using a plating solution having a concentration of 20 to 80 ppm, more preferably 60 to 80 ppm, it is excellent in hardness, glossiness, leveling property and cutting. It has become possible to provide a copper plating method capable of forming a copper plating film layer having excellent workability and excellent processing stability.

  In addition, since a copper plating layer having excellent machinability and good processing stability can be obtained, the life of the cutting tool can be extended, which can contribute to the cost reduction of the plate making process.

  Further, by using the method of the present invention, a highly accurate gravure plate and lens mold can be provided.

  First, a copper plating method in the case where a hardness maintenance agent is added in the presence of a brightener, an inhibitor, and a leveling agent will be described. A plating solution containing 150 to 270 g / L of copper sulfate, preferably 200 to 240 g / L, 40 to 100 g / L of sulfuric acid, preferably 40 to 80 g / L, and 50 to 150 ppm, preferably 80 to 120 ppm of chloride ion. Then, the gravure plate cylinder is alkali-degreased, activated with an acid, and plated in a plating tank. The supply of chlorine ions may be any of chlorine-containing compounds such as hydrochloric acid and sodium chloride.

  Examples of the hardness maintaining agent used in the present invention include poly (vinylamine), poly (vinylcarbazole), poly (ethyleneimine), poly (4-vinylpyridine), poly (vinylpyrrolidone), and poly (octamethyleneaminotriazole). And organic polymer compounds containing nitrogen such as poly (allylamine).

  With respect to additives other than the hardness maintaining agent, as a brightener, for example, bis (2-sulfopropyl) disulfide (disodium salt), bis (3-sulfopropyl) disulfide (disodium salt), bis (4-sulfobutyl) Disulfide (disodium salt), bis (p-sulfophenyl) disulfide (disodium salt), thiourea, sodium S- (2-ethylamido) -thiopropanoate, sodium S- (4-butylamido) -thiopropanoate, Thiourea such as sodium S- (3-propylamido) -thiopropanoate, sodium S- (3-propylamido) -thiobenzene-4-acid, sodium 3- (benzothiazolyl-2-thio) propylsulfonate, and the like; Organic thio compound derivatives can be used. As an inhibitor, for example, ethylene oxide such as polyethylene glycol, polypropylene glycol and polyethylene-polypropylene glycol, propylene oxide and their copolymers or block copolymers, polyvinyl alcohol, carboxyl cellulose, stearic acid-polyethylene glycol ether, stearyl Oxygen-containing organic high molecular compounds such as alcohol-polyethylene glycol ether, nonylphenol-polyethylene glycol ether, and octylphenol-polyethylene glycol ether can be used. As a leveling agent, for example, acetamido, propylamide, acrylamide, methacrylamide, N, N-dimethylacrylamide, N, N-diethylacrylamide, N, N-dimethylmethacrylamide, N, N-dimethylacetamide, N, N-diethylacetamide , N, N-diphenylacrylamide, poly (acrylamide), and other organic acid amides can be used.

The object to be plated can be applied to any of a gravure plate cylinder, a lenticular mold, a Fresnel lens mold, and a microlens mold. The plating conditions are as follows: the gravure plate cylinder, the lenticular mold, and the microlens molding mold are performed at a cathode current density Dk = 20 to 30 A / dm ² , and the plating for the Fresnel lens mold is performed at the cathode current density Dk = 3 to 8 A / dm ² is recommended. In particular, when plating on a flat metal plate, distortion occurs due to electrodeposition stress. Therefore, it is better to perform plating at such a low current density. The plating temperature may be any range as long as it is in the range of 25 to 45 ° C., but when plating is performed at a high current density, the higher the temperature, the more the occurrence of surface burning can be suppressed.

  After electrodeposition of copper plating on any of the objects to be plated, the surface is polished with a grindstone and finally polished with a buff to produce a base. In each case, cutting is performed in a desired pattern using a diamond cutting tool. When performing this cutting, it is important to control the hardness of the object to be cut. If the hardness is not kept within a certain range, burrs or the like may occur, and even the shape may differ from the designed value. When the gravure cylinder is manufactured by a helio engraving machine, if the hardness is low, burrs are likely to be generated in the cell, and a desired shape cannot be obtained, and it is difficult to manufacture a plate having a desired gradation curve. In manufacturing a lenticular mold or a Fresnel mold, peripheral speed, cutting depth and the like are important as cutting conditions, and it is necessary to control the hardness of copper plating as a material within a predetermined range. The Vickers hardness is measured as the hardness, and the hardness range is set to a range of Hv 180 to 240, preferably Hv 190 to 210.

  As a method of managing these additives, it is considered difficult to analyze and control additives in a plating solution containing a hardening agent used for cutting by a conventional CVS (Cyclic Voltammetric Stripping) method. Has been managed. On the other hand, additives used for printed wiring boards and the like are composed of a brightener, a suppressant, and a leveling agent, and since they do not contain a curing agent, they are easily analyzed and managed by the CVS method. The copper plating method of the present invention is characterized in that a nitrogen-containing polymer compound and an organic sulfur compound can be analyzed and managed using an analytical instrument without using a Hull cell test. That is, it has become possible to analyze and control nitrogen-containing polymer compounds using a high-performance liquid chromatograph (HPLC) and organic sulfur compounds using a capillary electrophoresis / mass spectrometer (CE / MS).

  The gravure cylinder is plated with chromium after engraving to prevent oxidation and increase the hardness of the surface. After cutting the lenticular mold, Fresnel mold and microlens mold, electroless nickel plating or electrolytic nickel plating is formed on the lens pattern surface with a plating thickness of several μm or less for the same purpose.

Hereinafter, examples of the present invention will be described in more detail. However, the present invention is not limited to the following examples.
<Example 1>
In a solution having a copper sulfate concentration of 210 g / L, a sulfuric acid concentration of 60 g / L, and a chloride ion concentration of 90 ppm, sodium S- (2-ethylamide) -thiopropanoate is 60 ppm, polyethylene glycol is 50 to 250 ppm, poly (acrylamide) is 50 to 150 ppm, and poly (acrylamide) is 50 to 150 ppm. (Vinylamine) 50 ppm was added, the bath temperature was kept at 35 ° C., and the gravure plate cylinder was plated. The brightener was analyzed using a capillary electrophoresis apparatus, and the reduced amount was replenished, and the replenishment was controlled within the range of the initial addition amount ± 10 ppm. The Vickers hardness of the layer plated by the above method was Hv210.

Next, when the obtained gravure plate cylinder was carved with a helio engraving machine, a good cell shape was formed, and a good gravure plate could be produced without a stylus needle being lost during cutting. When hundreds of gravure plates were produced by controlling the additives, the loss of the stylus needle hardly occurred, and the plate loss ratio in the helio-cutting process could be suppressed to 0.1 to 0.3%.
<Example 2>
In a solution having a copper sulfate concentration of 210 g / L, a sulfuric acid concentration of 60 g / L, and a chloride ion concentration of 90 ppm, sodium S- (2-ethylamide) -thiopropanoate is 60 ppm, polyethylene glycol is 50 to 250 ppm, poly (acrylamide) is 50 to 150 ppm, and poly (acrylamide) is 50 to 150 ppm. (Vinylamine) 50 ppm was added, and the bath temperature was kept at 35 ° C. to plate the brass plate for the Fresnel lens mold. The brightener was analyzed using a CE / MS apparatus, and the plating time was long, so a reduced amount was replenished on the way, and the replenishment was controlled within the range of the initial addition amount ± 10 ppm. The Vickers hardness of the layer plated by the above method was Hv210.

  Next, when the obtained plating plate for Fresnel lens is cut with a vertical lathe, a good Fresnel lens shape is formed, and a good Fresnel lens mold can be produced without causing a breakage of a special cutting tool during cutting. did it. The surface gloss was also good, and there was no sagging at the Fresnel mold crests, enabling uniform cutting.

Hereinafter, a comparative example of the present invention will be described.
<Comparative Example 1>
The composition of the plating solution was the same as in Example 1, and 60 ppm of sodium S- (2-ethylamido) -thiopropanoate, 50 to 250 ppm of polyethylene glycol, 50 to 150 ppm of poly (acrylamide), and 10 ppm of poly (vinylamine) were added. The temperature was kept at 35 ° C., and the gravure plate cylinder was plated. The obtained copper plating layer had good gloss and good leveling property, but had a Vickers hardness of Hv170. When the obtained gravure plate cylinder was carved with a helio engraving machine, cell shape deformation was observed and burrs were easily generated, and the quality was not such that it could be used as a gravure plate.
<Comparative Example 2>
The composition of the plating solution was the same as in Example 1, and 15 ppm of sodium S- (2-ethylamido) -thiopropanoate, 50 to 250 ppm of polyethylene glycol, 50 to 150 ppm of poly (acrylamide), and 200 ppm of poly (vinylamine) were added. The temperature was kept at 35 ° C., and the gravure plate cylinder was plated. The gloss of the obtained copper plating layer was good, but the Vickers hardness was Hv250. When the obtained gravure plate cylinder was engraved with a helio engraving machine, the cell shape was good, but streaks were conspicuous in the cell and the stylus needle was sometimes broken during cutting.

Next, apart from the above examples, a nitrogen-containing high-molecular compound serving as a curing agent was separately added with a nitrogen-containing water-soluble polymer (hereinafter referred to as a nitrogen-containing polymer), and the copper plating hardness when the addition amount was changed. The mechanism that causes the time-dependent change of the temperature was considered.
<Experiment 1>
First, a plating solution composition was prepared as follows.

・ Copper sulfate ・ pentahydrate 0.9M
・ Sulfuric acid 0.6M
Is used as a basic bath.
-SPS (Bis (3-sulfopropyl) disulfide disodium salt) 50ppm
・ PEG (polyethylene glycol) 200ppm
Was added thereto, and a nitrogen-containing polymer was added thereto at 5, 15, 20, 40, 60, 80, and 100 ppm, respectively, and used as a plating solution.

  Next, plating was performed with each plating solution, and left at room temperature to measure Vickers hardness.

  Further, in order to consider the mechanism of the temporal change of the copper plating hardness, the sulfur element, the carbon element, and the hydrogen element in the copper plating film were analyzed.

  FIG. 1 shows the change with time of the copper plating hardness due to the difference in the amount of the nitrogen-containing polymer added as a hardness maintenance agent. In the drawings, ppm is expressed in mg / L, which has the same meaning. According to this, when the addition amount of the nitrogen-containing polymer was 20 ppm, a rapid decrease was observed about 30 days after plating, and the Vickers hardness also fell below 180. At 40 ppm, it can be seen that the hardness is gradually reduced after plating, and the Vickers hardness is maintained at 180 or more even after 40 days. Further, with the addition amount of 60 ppm or more, almost no decrease in hardness is observed within the measurement period, and the Vickers hardness is maintained at 220 to 240.

The copper plating film was subjected to elemental analysis by a combustion method. The result is shown in FIG. In the drawings, ppm is expressed in mg / L, which has the same meaning. Up to the addition of the nitrogen-containing polymer at 0 to 60 ppm, the content of sulfur atoms and carbon atoms in the film increases with the increase of the nitrogen-containing polymer, but the nitrogen-containing polymer addition exceeds 60 ppm. In the region, the increasing tendency of these elements is slightly reduced. On the other hand, the content of hydrogen atoms increases with an increase in the amount of the nitrogen-containing polymer up to the addition of the nitrogen-containing polymer of 0 to 100 ppm, but thereafter, the increase slows down.
<Experiment 2>
Next, a plating solution having the same composition as in Experiment 1 was prepared except that the addition amount of the nitrogen-containing polymer as a hardness maintenance agent was set to 5, 10, and 20 ppm. Then, plating was performed with each plating solution, and the mixture was left at room temperature to measure Vickers hardness.

In connection with this measurement, FIB (Focused Io)
The crystal plane was etched by an n beam system (a focused ion beam device), and the crystal structure was observed by a SIM (Scanning Ion Microscope, a scanning ion microscope).

  FIG. 3 shows the change with time of the copper plating hardness at this time. In the drawings, ppm is expressed in mg / L, which has the same meaning. FIG. 4 shows a SIM image of the crystal structure when the amount of the nitrogen-containing polymer shown in FIG. 3 was 20 ppm. The photographing conditions in FIG. 4 were all set at a magnification of 7500 times.

  As a result, at a nitrogen-containing polymer addition amount of 20 ppm, the Vickers hardness is maintained at around 240 until 30 days after plating, and the crystal grain size at that time is as small as 0.3 to 0.5 μm. , The Vickers hardness dropped sharply and fell below 180. Then, looking at the SIM image on the 36th day, it was found that the particle size was rapidly increased and it was growing to about 4 to 10 μm or more. From these results, it was suggested that the cause of the decrease in hardness was the coarsening of the crystal grain size.

  Looking at the results of Experiments 1 and 2 above, the hardness of the copper plating film decreases with time when the amount of the nitrogen-containing polymer added is less than 60 ppm, but the hardness does not change with time at 60 ppm or more. This shows a phenomenon that the increase in the content of the sulfur element and the carbon element in the plating film becomes slow. From these facts, it is inferred that the copper plating hardness is such that these sulfur elements and carbon atoms are segregated at the crystal grain boundaries, and the crystal growth is suppressed by the pinning effect. Therefore, it is presumed that the mechanism of the decrease in copper plating hardness over time (aging softening phenomenon) is due to the fact that crystal growth proceeds because the contents of the hydrogen element and the carbon atom are insufficient. From this, there is no change in hardness with time when the nitrogen-containing polymer is added at 60 ppm or more.

  As described above, the amount of the nitrogen-containing polymer has been discussed from the viewpoint of Vickers hardness. It has been found that when the nitrogen-containing polymer is 60 ppm or more, there is no change with time. However, 100 ppm of the nitrogen-containing polymer in Experiment 1 was added. The copper plating film with the plating solution tended to be brittle. Therefore, it was found that the preferred value of the nitrogen-containing polymer was 60 to 80 ppm. In addition, it was found that the required copper plating hardness can be maintained at a concentration of 20 to 60 ppm in a short period of about 30 days.

4 is a graph showing a change over time in copper plating hardness depending on the amount of a nitrogen-containing polymer added. 3 is a graph showing the content of sulfur, carbon, and hydrogen elements in a copper plating film depending on the amount of a nitrogen-containing polymer added. 4 is another graph showing a change with time of the copper plating hardness depending on the difference in the amount of the nitrogen-containing polymer added. FIG. 4 is a view showing a SIM image of the copper plating structure of FIG. 3.

Claims (9)

  In copper electroplating, a copper plating hardness maintenance agent comprising an organic polymer compound added to a plating solution capable of maintaining a plated film hardness without decreasing over a long period of time.   The copper plating hardness maintenance agent according to claim 1, wherein the organic polymer compound contains a nitrogen atom in a structural formula.   A copper plating method, wherein a copper plating layer is formed on a surface of an object to be plated by applying a current to the object to be plated using a plating solution having an organic polymer compound concentration of 20 to 80 ppm.   The copper plating method according to claim 3, wherein the concentration of the organic polymer compound is 60 to 80 ppm.   The copper plating method according to claim 3, wherein a concentration of the nitrogen-containing compound is maintained and a plating layer is formed on the surface of the object to be plated.   A gravure plate obtained by using the copper plating method according to claim 3.   A copper cutting layer is provided on a metal plate by using the copper plating method according to any one of claims 3 to 5, and a die having a shape opposite to a lens pattern shape is cut and formed on the cutting layer. And lens mold.   The lens mold according to claim 7, wherein the lens pattern is any one of a lenticular lens, a Fresnel lens, a micro lens, and a prism lens.   9. The lens mold according to claim 7, wherein the surface of the lens mold is plated with any one of ultra-thin chromium plating, electroless nickel plating, and electrolytic nickel plating.