Aluminum electroplating solution

a technology of aluminum electroplating and solution, applied in the field of aluminum electroplating solution, can solve the problems of difficult conductivity of aluminum electroplating in aqueous solution type plating bath, shortening the bath life, and reducing current efficiency, so as to achieve enhanced precipitation efficiency of plating and improve the uniformity of film thickness

Inactive Publication Date: 2013-07-04
HITACHI LTD
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Benefits of technology

[0013]According to the present invention, a precipitation efficiency of plating is enhanced, a uniformity of a film thickness can be improved

Problems solved by technology

It is difficult to conduct an aluminum electroplating in aqueous solution type plating bath, because aluminum has a high affinity to oxygen and has a negative equilibrium potential compared to hydrogen.
However, all of these plating baths contain LiAlH4 or LiH which are very active in the baths, and thus react with oxygen or mois

Method used

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  • Aluminum electroplating solution

Examples

Experimental program
Comparison scheme
Effect test

example 1

[0028]1-ethyl-3-methylimidazolium chloride (commercially available from KANTO CHEMICAL CO., INC.; [EMIM]Cl) and anhydrous aluminum chloride (Wako Pure Chemical Industries, Ltd., AlCl3) were used. A weighing capacity was conducted in a glove box at a humidity set to 5% and a temperature set to 25° C., and AlCl3 was added so as to be a molar ratio of [EMIM]Cl:AlCl3=1:3 to obtain a 100 ml melt. The above mentioned melt was dissolved in 300 ml toluene (Wako Pure Chemical Industries, Ltd.), and a plating solution was prepared so as to be 400 ml in a total volume. The resulting electrolyte 400 ml was charged into a polypropylene-made electrolytic bath having longitudinal×transversal×height of 100 mm×50 mm×100 mm.

[0029]Next, an aluminum plate of purity 99.9% having longitudinal×transversal of 75 mm×75 mm and a thickness of 2 mm, as an anode electrode, and a copper foil having longitudinal×transversal of 50 mm×50 mm and a thickness of 0.1 mm, as a cathode electrode, were facing-positioned a...

examples 2 to 12

[0034]Aluminum chloride salts AlCl3 were dissolved by using organic compounds and organic solvents shown at Table 1 so as to become one of several salt concentrations A (mol / l), to prepare plating solutions of Examples 2 to 12 as well as in Example 1.

[0035]An aluminum electroplating was conducted at an electric current density −10 mA / cm2 for 20 minutes or an electric current density −20 mA / cm2 for 10 minutes by using a constant electric current source. Then, an evaluation of a current efficiency and an observation of a surface state of the plating film were conducted. It was conducted at a voltage of 3V or less in the plating. The current efficiency was determined by determining a precipitation amount of aluminum by actual measurement, comparing this to a precipitation amount precalculated based on an electric current value of a coulomb meter, and determining a ratio to the latter precipitation amount calculated as a percentage. The results are shown at Table 1.

[0036]As clear from t...

example 13

[0037]According to the plating method as well as in Example 1, a plating was conducted onto a material to be plated which is a copper foil having a center folded at 90 degree in the L-shape. In result of measuring film thicknesses of five portions of a copper foil face, good results of a plating film thickness of 4 μm and a distribution within 8% were obtained. The current efficiency was as good as 97%.

[0038]As clear from these results, it was found that, when the solvent and the solute as in the present Example were used, a large electric current of a electroplating can be conducted, a plating of aluminum can be achieved efficiently and in a short period of time, and parts having a uniform plating applied were able to be provided even from a steric shape.

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Abstract

The purpose of the present invention is to provide an aluminum electroplating solution that allows aluminum electroplating to be conducted efficiently and in a short period of time, can increase the amount of electricity in the current of electroplating, and has high solubility in a nonaqueous solvent. This aluminum electroplating solution is characterized by comprising an aluminum metal salt, an ionic liquid obtained by an organic compound forming an ion pair with the aluminum metal salt, and an organic solvent having a dielectric constant of 8 or less. It is preferable for the volume percentage of the organic solvent in relation to the total volume of the ionic liquid and the organic solvent to be at least 30%, and for at least one of the following to be included as the organic solvent having a dielectric constant of 8 or less: hexane, toluene, diethyl ether, ethylacetate, cyclohexane, xylene, benzene, naphthalene, heptane, cyclopentyl methyl ether, and dioxane.

Description

TECHNICAL FIELD[0001]The present invention relates to an aluminum electroplating solution using an organic solvent (non-aqueous solvent).BACKGROUND ART[0002]It is difficult to conduct an aluminum electroplating in aqueous solution type plating bath, because aluminum has a high affinity to oxygen and has a negative equilibrium potential compared to hydrogen. Thus, in the aluminum electroplating, many organic solvent plating solutions have been studied. Typical ones of this organic solvent type plating bath include AlCl3 and LiAlH4 or LiH dissolved in ether, or AlCl3 and LiAlH4 dissolved in THF (tetrahydrofuran). However, all of these plating baths contain LiAlH4 or LiH which are very active in the baths, and thus react with oxygen or moisture, when being present, to be decomposed and lower a current efficiency and shorten a bath life also. Under the circumstances, Patent Literatures 1 and 2 etc. report a molten salt electrolytic plating solution containing a dimethylsulfone solvent a...

Claims

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Application Information

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IPC IPC(8): C25D3/44
CPCC25D3/44C25D3/665
Inventor NAKANO, HIROSHINEGISHI, YOSHINORIAKAHOSHI, HARUO
Owner HITACHI LTD
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