Electrolysis: processes – compositions used therein – and methods – Electrolytic coating – Coating predominantly nonmetal substrate
Patent
1992-04-30
1994-01-25
Niebling, John
Electrolysis: processes, compositions used therein, and methods
Electrolytic coating
Coating predominantly nonmetal substrate
205162, 205183, 205184, C25D 500
Patent
active
052813266
DESCRIPTION:
BRIEF SUMMARY
BACKGROUND OF THE INVENTION
The present invention refers to a method with the objective of forming a layer with good electrical conductivity to different dielectric ceramic materials. In particular, the invention refers to a method for providing ceramic components for microwave band applications, e.g. ceramic resonators to be used in duplex filters and in the receiver front end pass filters. The advantages of these ceramic components are their small sizes and their minimal losses and their excellent stability.
Whenever ceramic materials are used in the microwave band, good electrical conductivity, corrosion resistance, and good adhesion of the ceramic surface are required of the coating.
The most commonly used coating methods today are coating by wire paste and chemical coating (wet process). Paste coating is a relatively expensive process. Chemical coating has several phases and may influence the electrical characteristics of the ceramic material. In order to obtain sufficient adhesion, the first etching treatments in the chemical coating process are different when different ceramic materials are used and therefore they have to be established separately for every material. In some cases, it is possible to provide the adhesive layer by sputtering, but this method is difficult in connection with components with deep holes or cavities.
The German application publication DE-3706951 discloses a method concerning metal coating of ceramic materials. According to this method, a thin metal coating is formed on the ceramic material by currentless coating, the metal coating is heat-treated and chemically etched to improve the adhesion, after which the surface of the ceramic material is metal-coated by a currentless coating process. This process includes several phases and different process phases should be applied to different ceramic materials.
SUMMARY OF THE INVENTION
The objective of the present invention is to provide a method by which the above mentioned disadvantages could be eliminated. The essential characteristics of the invention are described in the attached claims.
The advantage of the method according to the present invention is, in comparison with the methods of prior art, is also the fact that the Q values reached by it in the resonator applications is better (the quality factor or the relation between the energy stored in the field and the energy lost in the dissipation during one phase). The coating method according to the invention is considerably simpler than the chemical coating method, and the coating obtained by it will be significantly cheaper than by the coating method with the paste method. This is due to the fact that most of the conducting coating is obtained by electrolytical incrementation.
In the method according to the invention, the ceramic piece of the desired form is first washed by an organic detergent in the ultrasound washing machine. The detergent could, for instance, be an acetone or an isopropanol. The ceramic material used could be any generally used ceramic material used in the branch; the chemical composition is not essential, as far as the method itself is concerned. After washing the pieces are dried. Then the pieces are coated by a paste with good electrical conductivity. The paste can be e.g. a silver paste, a commercial product including about 80 percent silver, terpineol, leaded glass and a solution. The silver paste layer is sintered by having the paste coated piece in the temperature of 300.degree. C., then by rising the temperature to 850.degree. C. for 20 minutes, and then further to 900 .degree. C. for 5 minutes, after which the piece will be held in 900.degree. C. for 15 minutes, and cooled after that. The silver paste thus created has a thickness of about 5 to 10 .mu.m and it will work as an adhesive layer between the ceramic material and the coating with electrical conductivity. Another example of a paste with electrical conductivity is a copper paste that can replace, when desired, the silver paste.
The etching of the ceramic surface is not necessary at a
REFERENCES:
patent: 3607681 (1971-09-01), Cooke et al.
patent: 3865558 (1975-02-01), Roth et al.
patent: 4668925 (1987-05-01), Towatari et al.
patent: 4748086 (1988-05-01), Akoh
patent: 4808274 (1989-02-01), Nguyen
patent: 5066620 (1991-11-01), Sunahara et al.
Lowenheim, F. A., "Modern Electroplating", 3rd edition, John Wiley & Sons, Inc., New York, pp. 571-583.
F. A. Lowenheim, "Electroplating", McGraw-Hill, Inc., New York, 1978, pp. 416-418.
Eiichi Asada et al., Electrically Conductive Composition for Terminal Electrode on Ceramic Electric Capacitor, Chem. Abstr., vol. 112, 244499s.
Hisano Nakakura et al., Laminated Ceramic Capacitor Having Triple-Layered Outer Electrode, Chem. Abstr., vol. 114, 134461g and vol. 114, 113458w.
Chemical Abstracts, vol. 112, No. 26, Jun. 25, 1990, (Columbus, Ohio, U.S.), p. 626, Abstract 244499s, & JP, A, 239410 (Eiichi Asada et al.).
Dialog Information Services, File 351, World Patent Index 81-91, Dialog Accession No. 003174565, KKC.
KK, "Ceramic Capacitor Mfr. by Depositing Silver Paste Layers on Dielectric Ceramic Body, Firing to Form Silver Electrodes and Forming Nickel and Solder Layers", JP 56030718, A, 810327, 8120 (Basic).
LK-Products OY
Mayekar Kishor
Niebling John
LandOfFree
Method for coating a dielectric ceramic piece does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Method for coating a dielectric ceramic piece, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Method for coating a dielectric ceramic piece will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-725655