Classifications

• • C—CHEMISTRY; METALLURGY
  • C23—COATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; CHEMICAL SURFACE TREATMENT; DIFFUSION TREATMENT OF METALLIC MATERIAL; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL; INHIBITING CORROSION OF METALLIC MATERIAL OR INCRUSTATION IN GENERAL
  • C23C—COATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; SURFACE TREATMENT OF METALLIC MATERIAL BY DIFFUSION INTO THE SURFACE, BY CHEMICAL CONVERSION OR SUBSTITUTION; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL
  • C23C18/00—Chemical coating by decomposition of either liquid compounds or solutions of the coating forming compounds, without leaving reaction products of surface material in the coating; Contact plating
  • C23C18/16—Chemical coating by decomposition of either liquid compounds or solutions of the coating forming compounds, without leaving reaction products of surface material in the coating; Contact plating by reduction or substitution, e.g. electroless plating
  • C23C18/31—Coating with metals
  • C23C18/38—Coating with copper
  • C23C18/40—Coating with copper using reducing agents

Definitions

• This invention relates to a chemical copper plating solution. More particularly, it is concerned with a chemical copper plating solution having a novel composition which makes it possible to deposit copper at a high speed and is stable over a prolonged period of application and can form a plated film having favourable mechanical properties.
• a chemical copper plating solution may usually contain as essential components a water-soluble copper salt such as copper sulfate, cupric chloride, etc.; a complexing agent such as ethylenediaminetetraacetic acid (EDTA), N,N,N',N'-tetrakis-(2-hydroxypropyl)ethylenediamine, Rochelle salt, etc.; a reducing agent such as formaldehyde, dimethylaminoborane, sodium borohydride, etc.; a pH adjustor such as sodium hydroxide, potassium hydroxide, etc.; and, where necessary, a surface active agent such as a polyethylene oxide, a polyether, a polyester, etc.
• a water-soluble copper salt such as copper sulfate, cupric chloride, etc.
• a complexing agent such as ethylenediaminetetraacetic acid (EDTA), N,N,N',N'-tetrakis-(2-hydroxypropyl)ethylenediamine, Rochelle
• a chemical copper plating solution having the composition of such components generally tends to lack stability and readily undergo self-decomposition; moreover, a plated film or deposited film made from said chemical plating solution is brittle and insufficient in mechanical strength, particularly bending strength for practical utility.
• the primary object of this invention is to provide a chemical copper plating solution having a novel composition which can dissolve the aforesaid problems, show a good stability, without reducing high speed deposit in plating, and provide good mechanical properties, especially a favourable spreadability of the resultant plated film.
• the chemical copper plating solution of this invention is a chemical copper plating solution containing a copper salt, a complexing agent, a reducing agent and a pH adjustor, which further comprises at least one of the under-mentioned Groups (A) and (B):
• the chemical copper plating solution according to this invention is composed of, in addition to the four components of a copper salt, a complexing agnet, a reducing agent and a pH adjustor, at least one selected from the group consisting of, as Group (A), a nonionic surface active agent mentioned below and at least one selected from the group consisting of 1,10-phenanthroline, a 1,10-phenanthroline derivative, 2,2'-dipyridyl, 2,2'-biquinoline and a water-soluble cyan compound; and as Group (B), an organic sulfur compound and an ethyleneamine compound.
• A a nonionic surface active agent mentioned below
• 1,10-phenanthroline 1,10-phenanthroline derivative, 2,2'-dipyridyl, 2,2'-biquinoline and a water-soluble cyan compound
• B an organic sulfur compound and an ethyleneamine compound.
• a copper salt may supply a copper ion, while a reducing agent may reduce said copper ion to a metallic state.
• a complexing agent may form a stable complex with copper ions to prevent, in a plating bath (alkaline), a formation of cupric hydroxide, while a pH adjustor may adjust the optimum plating deposit potential in a plating bath.
• the nonionic surface active agent may contribute to mechanical properties and deposit rate of a plating solution and is represented by the formula (I) or (II).
• each of m l , m 2 , n 1 and n 2 is an integer of 1 or more. If any of them is 0 (zero), a nonionic surface active agent shows a low solubility so that a sufficient amount thereof to contribute to improvement in stability or mechanical properties of a plating solution could not be dissolved in a plating solution.
• m l + n 1 or m 2 + n 2 is increased, stability and mechanical properties of a plating solution may be correspondingly improved. In any case, its effect may approximately reach the upper limit at the neighborhood of 20 to a saturated state. Thus, there is particularly no upper limit with regard to m l + n 1 or m 2 + n 2 , but not more than 500 is preferred in view of workability.
• a concentration of the compound (I) or (II) in a plating solution is preferably in the range of 10 mg/l to 30 g/1.
• a concentration of the compound (I) or (II) in a plating solution is preferably in the range of 10 mg/l to 30 g/1.
• m 1 + n 1 and m 2 + n 2 is less than 20, a range of 30 mg/l to 20 g/1 is preferred.
• m 1 + n 1 and m 2 + n 2 is not less than 20, a range of 10 mg/l to 5 g/1 is preferred.
• 1,10-phenanthroline a 1,10-phenanthroline derivative, 2,2'-dipyridyl, 2,2'-biquinoline or a water-soluble cyan compound, in order that the aforesaid effects by nonionic surface active ageant, especially stability of a plating solution or mechanical properties of a plated film may be far more enhanced.
• the 1,10-phenanthroline derivative may preferably have a substituent such as a lower alkyl group, e.g., a methyl group, an ethyl group, etc. or a phenyl group and there may illustratively be mentioned 2,9-dimethyl-1,10-phenanthroline, 4,7-diphenyl-2,9-dimethyl-1,10-phenanthroline, 4,7-diphenyl-1,10-phenanthroline and so on.
• a substituent such as a lower alkyl group, e.g., a methyl group, an ethyl group, etc. or a phenyl group and there may illustratively be mentioned 2,9-dimethyl-1,10-phenanthroline, 4,7-diphenyl-2,9-dimethyl-1,10-phenanthroline, 4,7-diphenyl-1,10-phenanthroline and so on.
• water-soluble cyan compound there may be mentioned, for instance, potassium cyanide, sodium cyanide, sodium nitroprusside, potassium ferrocyanide, potassium ferricyanide, potassium tetracyanoniccolate and so on.
• a total amount of 1,10-phenanthroline, a 1,10-phenanthroline derivative, 2,2'-dipyridyl and 2,2'-biquinoline to be added is preferably 1 - 200 mg/l, a range of 2 - 50 mg/l being particularly preferred. If the added amount is less than 1 mg/1, one could not obtain effects at all;
• An amount of the water-soluble cyan compound to be added is preferably 1 mg/1 to 3 g/l, a range of 5 mg/l to 1 g/1 being particularly preferred. If the added amount is less than 1 mg/l, it does not at all contribute to improvement in stability and mechanical properties, while, if more than 3 g/l, there would undesirably produce a lowered deposit rate or a reduced mechanical property of a plated film.
• the organic sulfur compound added as the Group (B) may contribute to improved stability of a plating solution, while the ethyleneamine compound may contribute to speed-up of a deposit rate.
• organic sulfur compound which may be employed as the Group (B)
• organic sulfur compound which may be employed as the Group (B)
• 2-mercaptobenzothiazole thiourea, ethylene thiourea, l-phenyl-2-thiourea, l-allyl-2-thiourea, thiodiglycol, thiomalic acid, thiodiethanol, 2-mercaptobenzimidazole, dodecylmercaptan, thioglycolic acid, thiodiglycolic acid, etc.
• An amount of the organic sulfur compound to be added is preferably 0.01 mg/l to 10 mg/l, a range of 0.1 mg/l to 5 mg/l being particularly preferred. If the added amount is less than 0.01 mg/l, stability of a plating solution is not so much improved; if more than 10 mg/l, a deposit rate is extremely lowered, which leads to a reduced working efficiency.
• ethyleneamine compound there may be mentioned, for instance, ethylenediamine, diethylenetriamine, triethylenetetramine, tetraethylenepentamine, pentaethylenehexamine and so on.
• An amount of the compound to be added is preferably 1 mg/l to 500 mg/l, a range of 5 mg/l to 100 mg/l being particularly preferred. If the added amount is less than 1 mg/l, a deposit rate of the plating solution or mechanical properties of the plated film is not so much improved; if more than 500 mg/l, a plating solution becomes unstable.
• the present invention has the characteristics that at least one of the above Groups (A) and (B) is further incorporated, in addition to the four components of a copper salt, a complexing agent, a reducing agent and a pH adjustor; but, if the present plating solution contains only the above Group (A), stability and deposit rate of a plating solution and mechanical properties of a plated film may be far more improved by the addition of at least one of the organic sulfur compounds and ethyleneamine compounds.
• At least one of a 2,2'-dipyridyl and a water-soluble cyan compound may be further added at a concentration in the plating solution of 1 - 100 mg/l, preferably 5 - 50 mg/l, in order to improve spreadability of a plated film and stability of plating solution. If the added amount is less than 1 mg/l, improvement in spreadability of a plated film or stability of a plating solution could not be expectable. If more than 100 mg/l, there will be produced a lowered deposit rate of a plating solution or a saturated effect for improved spreadability, which leads to useless increase in the added amount.
• the chemical copper plating solution of the present invention can become a chemical copper plating solution having respective merits of the compounds, that is to say, the plating solution having an excellent stability and producing a highly spreadable plated film with a high speed deposit, when the above compounds having the above-mentioned functions are used in combination therewith at the predetermined proportion.
• Preferable plating conditions under which the present chemical copper plating solution may be applied, are the range of a temperature of 40 - 80 °C, more preferably 50 - 70 °c and a p H value of 10.8 - 13.0, more preferably 12.0 - 13.0. According to such plating condition, characteristic of the present plating solution can be fully put to use and there can be formed a plated film which can be deposited at a high speed and has a high spreadability.
• a stainless steel plate with a thickness of 0.3 mm was polished with a cleanser, dipped in a 10 % sodium hydroxide solution at 80 °C for one minute, taken out and washed with water. Then, it was dipped in a 10 % sulfuric acid at ordinary temperature for 30 seconds and washed with water to clean the surface thereof. The resultant stainless steel plate was then dipped in a solution having the composition of;
• the plate was dipped in a solution having the composition of; for one minutes and washed in a running water for one minute.
• the chemical copper plating solutions thus prepared were measured for deposit rate of copper. Such a measurement was accomplished by dipping a copper foil with a thickness of 10 um, the surface of which was previously cleaned, in the plating solution under conditions of a plating temperature of 60 °C and a pH value of the plating solution of 12.5 for one hour and calculating a deposit rate from the difference in weight before and after plating.
• the catalyzed stainless steel plate with a thickness of 0.3 mm as described above was treated with the chemical copper plating solution to deposit plated films with a thickness of 30 - 35 um over both sides thereof, respectively, using plating conditions of a plating temperature of 60 °C and a pH value of the plating solution of 12.5.
• the copper plated film thus deposited was peeled off from the stainless steel plate and applied to a spreadability test.
• Spreadability was measured according to the following folding test at 180 °C; a plated film was first folded to one direction at 180 0 to make a fold and then restored to an original position and pressed to flat the fold. Such a procedure was counted as one folding and repeated until the plated film was broken at the folding portion. According to this test, spreadability of the plated film is represented in terms of the numbers of foldings which the plated film could resist.
• nonionic surface active agents of the formulae (I) and (II) are represented with A-x and B-x, respectively, said "x"s in A-x and B-x indicating m 1 + n 1 and m 2 + n 2 , respectively.
• Comparative Example 1 a plating solution was prepared in the same manner as in the above Examples except for using a compound other than the present invention in place of the component other than the nonionic surface active agents in the Group(A).
• a stainless steel plate with a thickness of 0.3 mm was polished with a cleanser, dipped in a 10 % sodium hydroxide solution at 80 °c for 5 minutes, taken out and washed with water. Then, it was dipped in a 10 % hydrochloric acid at ordinary temperature for 5 minutes and washed with water to clean the surface thereof.
• the resultant stainless steel plate was dipped in a solution having the composition of;
• the chemical copper plating solution thus prepared was measured for deposit rate of copper. Such a measurement was accomplished by dipping a copper foil with a thickness of 10 um, the surface of which was previously cleaned, in the plating solution for one hour under conditions of a plating temperature of 60 °C and a p H value of the plating solution of 12.3 and calculating a deposit rate from the difference in the weight before and after plating.
• Plating solutions were prepared in the same manner as in the above Examples 13 - 24 except that either of an organic sulfur compound and an ethyleneamine compound was incorporated or none of both was added. Similar tests as in the above Examples 13 - 24 were carried out to those and the results are also shown in Table 2.
• the chemical copper plating solution of the present invention can show an excellent stability usable over prolonged period, together with a high speed deposit, and produce a plated film having superior mechanical properties, inter alia, a good spreadability as illustrated with folding strength.
• application of the chemical copper plating solution of the present invention can greatly improve working efficiency for plating and further enhance reliability in forming a plated film.
• the chemical copper plating solution of the present invention may be most suitable for production of, e.g., a continuity circuit in a print distributing plate and is highly valuable in an industrial field.

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• Chemical & Material Sciences (AREA)
• General Chemical & Material Sciences (AREA)
• Chemical Kinetics & Catalysis (AREA)
• Engineering & Computer Science (AREA)
• Materials Engineering (AREA)
• Mechanical Engineering (AREA)
• Metallurgy (AREA)
• Organic Chemistry (AREA)
• Chemically Coating (AREA)
• Manufacturing Of Printed Wiring (AREA)

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Citations (7)

• 1985
  • 1985-08-07 EP EP85109921A patent/EP0179212B1/fr not_active Expired - Lifetime
  • 1985-08-07 DE DE8585109921T patent/DE3585017D1/de not_active Expired - Lifetime

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