Electrolysis: processes – compositions used therein – and methods – Electrolytic coating – Utilizing subatmospheric or superatmospheric pressure during...
Reexamination Certificate
2002-03-04
2004-09-21
Koehler, Robert R. (Department: 1775)
Electrolysis: processes, compositions used therein, and methods
Electrolytic coating
Utilizing subatmospheric or superatmospheric pressure during...
C205S705000, C205S722000, C204S225000, C204S242000, C204S275100
Reexamination Certificate
active
06793793
ABSTRACT:
TECHNICAL FIELD
This invention relates to a method of electrochemical treatment such as electroplating, etc. and an electrochemical reaction apparatus thereof, which method and apparatus are suited to be used for electrochemical treatment such as, for example, electroplating, and the like, which method and apparatus are capable of executing various treatment processes safely, rationally and rapidly, using supercritical or subcritical matter such as, for example, carbon dioxide, which method and apparatus are capable of processing the used-carbon dioxide, treatment solution, etc. rationally and rapidly, which method and apparatus are capable of suppressing the consumption of the amount of the acid picking solution, plating solution, etc. and reducing the amount of liquid waste generated from the plating operation thereby preventing the pollution of the environment and achieving the improvement of the working environment, the enhancement of productivity and the reuse of the liquid waste, which method and apparatus are capable of attaining a beautiful finishing by remarkably improving the adhesion power of plating, which method and apparatus are capable of easily realizing fine and uniform plating even at the reverse side and recessed-portion of the matter to be treated, which method and apparatus are capable of attaining the elimination miniaturization and light-weight of a vessel(s) required for each treatment thereby achieving the reduction of the cost of equipment and the compactness of the installation space, and which method and apparatus are capable of executing electrochemical reaction rationally and efficiently by pressurizing the reaction vessel and suppressing electrolysis of a solvent in the electrolytic solution for the enhancement of electric current efficiency, thereby obtaining a fine and thin metallic film.
BACKGROUND ART
As a representative example of a convention electrochemical reaction, there can be listed electroplating. The electroplating plays an important role in industrial use such as decoration, corrosion prevention, corrosion resistance, rust prevention and the like. Also, as an example of a method of mass production of a specific metal, there can be listed electrorefining. Besides the above, as examples of electrochemical treatment in which application of an external electric field is employed, there can be listed electroforming, electrophoretic coating and the like, which are all in the category of cathodizing treatment, and formation of anodic oxide film of aluminum, electrochemical polishing, electrochemical machining, electrophoretic plating and the like, which are all in the category of anodizing treatment. Moreover, as examples of a method in which application of an external electric field is not employed, there can be listed electroless plating, chemical conversion treatment and the like.
Various attempts have heretofore been made in order to improve the reaction efficiency or to improve the uniformity and adhesion power of film in respect of the above-mentioned various electrochemical reaction methods.
As one example of them, a method is known in which a surface active agent is used. The surface active agent plays an important role in suppressing gas generated from electrochemical reaction, breaking water, suppressing the occurrence of stain, assisting drying and the like.
In addition, by using the surface active agent, reaction can be executed without using any auxiliary electrode even at a feeble electric current portion with high electric characteristics. Owing to this feature, the consumption of electric power can be reduced and the speed of deposition and dissolution can be increased. As a result, the leveling effect can be increased.
However, the surface active agent is actually not used because of its high price, complicated process, etc. Therefore, development of a new technique is demanded which is capable of enhancing the reactability and reaction efficiency and improving the uniformity and adhesion power of the film.
Also, in the technical field of electrochemical reaction such as electroplating, etc., there is encountered with a problem of treatment of liquid waste such as used-plating solution. This is regarded as a problem to be solved as more rapidly as possible with the increasing concern about the environment problem.
The liquid waste treatment includes three stages of process, namely, decomposition of toxic matter contained in liquid waste, separation and removal of toxic matter from the liquid waste, and treatment and disposal of the separated matter.
Especially, with respect to the separation of toxic matter from the liquid waste, a method is widely accepted, in which a chemical is applied to the liquid waste to solidify the toxic matter and then the solidified toxic matter is removed.
However, this method is, in many cases, executed using a large scaled-equipment which, in general, cannot be said very efficiency and it cannot fully cope with the problem of treatment of liquid waste under the recent increasing strict restriction by rules and regulations.
Moreover, conventionally, it was necessary to clean the target matter such as a plated electrode after electrochemical reaction. This cleaning process is normally executed by rinsing the target matter in stored water, exposing the target matter to running water or the like. Thus, it gives rise to a problem that the process becomes complicated. Moreover, the solution used for cleaning becomes a large quantity of liquid waste and this again raises the above-mentioned problem of treatment of liquid waste.
The conventional electroplating process can roughly be classified into a preceding treatment process (namely, pre-treatment process), a plating treatment process and a succeeding treatment process (namely, post-treatment process). Of these treatment processes, the preceding treatment process includes a step of degreasing and cleaning. In ordinary practice, this preceding treatment process is executed in an exclusive-use vessel containing a prescribed treatment solution, the vessel being then heated and the matter to be treated being then immersed in the treatment solution for a predetermined time.
Therefore, a plurality of vessels and work spaces for them are required which results in high cost of the equipment. Moreover, a poor working environment is created where work must be done under such circumstance that the treatment solution is scattered and hazardous gases are generated. In addition, since it takes a long time for immersing the matter to be treated in the treatment solution, productivity is lowered.
As a degreasing/cleaning method, various methods are proposed such as, alkali heating, electrocleaning, solvent cleaning, emulsion cleaning and the like. However, all of them require the use of chemicals and special equipment. Moreover, it is required for them to immerse the matter to be treated in various treatment solutions or expose the matter to be treated to evaporation of the treatment solutions. Therefore, much time is required for them to break water.
As one attempt to solve such problems, Japanese Patent Application Unexamined Publication No. 2000-63891, for example, discloses a cleaning apparatus in which carbon dioxide in a supercritical state is supplied into a chamber of small capacity and contacted with matter to be cleaned which is stored in the chamber, and then, the matter to be cleaned is heated or vibrated so that the PCB adhered to the matter to be cleaned is dissolved and removed.
In this conventional cleaning apparatus, the carbon dioxide in a critical state is all discharged to the atmospheric air after the cleaning operation is finished. Therefore, in the case where an electroplating product having a larger capacity than the above-mentioned chamber is to be cleaned, the consumption of carbon dioxide is increased, thus making the method of using this conventional apparatus expensive. Moreover, it can be expected that the working environment is deteriorated due to discharge of carbon dioxide. Thus, this conventional apparatus is difficult to be act
Asai Hiroe
Asai Yoshihiro
Iwao Fumiko
Miyata Seizo
Sone Masato
Jordan and Hamburg LLP
Yoshida Hideo
LandOfFree
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