Chemistry: electrical and wave energy – Processes and products
Patent
1981-02-18
1986-03-18
Niebling, John F.
Chemistry: electrical and wave energy
Processes and products
204 30, 204 384, 427 42, 427 97, 427 98, 4273831, 427437, 4274431, C25D 554, C23C 1814
Patent
active
045766894
DESCRIPTION:
BRIEF SUMMARY
FIELD OF THE INVENTION
The present invention relates to the art of electrochemical metallization and, more particularly, to a solution and a process for electrochemical metallization of dielectrics.
BACKGROUND OF THE INVENTION
Known in the art and extensively employed for electrochemical metallization of dielectrics are solutions having various compositions. Thus, use is made of solutions of surfactants for surface degreasing, i.e. imparting hydrophilic properties thereto; acid solutions of tin chloride to sensitize the surface; solutions of palladium chloride for activation of the surface, i.e. deposition, on the dielectric surface, of metallic palladium particles which catalyze the process of chemical copper plating; solutions for chemical copper-plating for application, onto the dielectric surface, of a thin (1 to 3 .mu.m) current-conducting layer; solutions of electrolytes for electroplating build-up of a metal layer of a required thickness (cf. USSR Inventor's Certificate No. 240061, published 21.03.1969, Bulletin No. 12, Cl. H 05 K 3/06).
Known in the art are also modifications of the abovementioned combination of solutions characterized, in particular, in that for the surface activation use is made of salts of noble metals (gold, silver, platinum and the like) and a current-conducting layer of other metals (nickel, cobalt, iron and the like) is chemically deposited onto the activated surface. Accordingly, the solutions for chemical metallization are also different and consist of a salt of a reducible metal (copper, nickel, cobalt, iron and the like), a reducing agent (sodium boron hydride, formaldehyde, hydrazine and the like) and a stabilizer--a solution of a complex-forming agent for the metal ions (citric acid, Seignette salt and the like), or a surface-active substance (dodecylaminacetate and the like) (cf. U.S. Pat. Nos. 3,515,649 of June 2, 1970; Int. Cl. C 23f 17/00; US Cl. 204-38; 3,553,085 published Jan. 5, 1971; Int. Cl. C23 d 5/60, US Cl. 204-30; 3,764,488 published Oct. 9, 1973, Int. Cl. B 44 d 1/09, US Cl. 240-381.3; 3,563,784 published Oct. 16, 1971, Int. Cl. C 23c 3/00, US Cl. 117-47).
Also known is a solution for electrochemical metallization of dielectrics employed for the surface activation before a chemical metallization and having the following composition: PdCl.sub.2 --0.5-1.0 g/l; H.sub.2 SO.sub.4 --40-200 ml/l; SnCl.sub.2 --30-50 g/l; HCl--10-50 ml/l (U.S. Pat. No. 3,650,913 published Mar. 21, 1972; Int.Cl. C 23b 50/60, US Cl. 204-30).
Also known is a combination of solutions for electrochemical metallization of through holes of multi-layer printed boards which differs from those specified hereinbefore by the additional use of a hydrochloric-acid solution of rhodium chloride prior to the activation of the surface of the hole walls which has the following composition: rhodium chloride--4.5-5 g/l; hydrochloric acid--250-200 mg/l (cf. USSR Inventor's Certificate No. 470940, published May 15, 1975, Bulletin No. 18, Int.Cl. H 05K (3/00).
All the above-mentioned solutions for electrochemical metallization contain economically inefficient and difficult-to-obtain substances such as salts of noble metals (palladium, gold, silver, platinum, rhodium), stabilizing agents such as citric acid and Seignette salt. The above-discussed prior art solutions for electrochemical metallization have low stability, thus necessitating frequent correction and replacement. These solutions adapted for electrochemical metallization do not ensure a required quality of application of chemical coatings and an adequate reproducibility thereof.
Also known in the art is a solution for electrochemical metallization of dielectrics which has the following composition, g/l: copper salt (as calculated for metallic copper)--35-40; potassium pyrophosphate--450-500; ammonia--3-6; citric acid--10-20 (cf. USSR Inventor's Certificate No. 159368 published 1963. Bulletin No. 24, Cl. C 23 B 5/18). This solution has but a weak activation power relative to dielectrics, wherefore it does not ensure a required quality of the
REFERENCES:
patent: 3046159 (1962-07-01), Brookshire
patent: 3307972 (1967-03-01), Ehrhardt
patent: 3716462 (1973-02-01), Jensen
patent: 3994727 (1976-11-01), Polichette
patent: 4209331 (1980-06-01), Kukanskis et al.
Boldyrev Vladimir V.
Lomovsky Oleg I.
Makkaev Almaxud M.
Mikhailov Jury I.
Leader William T.
Niebling John F.
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