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
  • C23C18/18—Pretreatment of the material to be coated
  • C23C18/20—Pretreatment of the material to be coated of organic surfaces, e.g. resins
  • C23C18/28—Sensitising or activating
• • 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
  • C23C18/18—Pretreatment of the material to be coated
  • C23C18/20—Pretreatment of the material to be coated of organic surfaces, e.g. resins
  • C23C18/28—Sensitising or activating
  • C23C18/30—Activating or accelerating or sensitising with palladium or other noble metal
• • H—ELECTRICITY
  • H05—ELECTRIC TECHNIQUES NOT OTHERWISE PROVIDED FOR
  • H05K—PRINTED CIRCUITS; CASINGS OR CONSTRUCTIONAL DETAILS OF ELECTRIC APPARATUS; MANUFACTURE OF ASSEMBLAGES OF ELECTRICAL COMPONENTS
  • H05K3/00—Apparatus or processes for manufacturing printed circuits
  • H05K3/10—Apparatus or processes for manufacturing printed circuits in which conductive material is applied to the insulating support in such a manner as to form the desired conductive pattern
  • H05K3/18—Apparatus or processes for manufacturing printed circuits in which conductive material is applied to the insulating support in such a manner as to form the desired conductive pattern using precipitation techniques to apply the conductive material
  • H05K3/181—Apparatus or processes for manufacturing printed circuits in which conductive material is applied to the insulating support in such a manner as to form the desired conductive pattern using precipitation techniques to apply the conductive material by electroless plating
• • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
  • Y10—TECHNICAL SUBJECTS COVERED BY FORMER USPC
  • Y10T—TECHNICAL SUBJECTS COVERED BY FORMER US CLASSIFICATION
  • Y10T428/00—Stock material or miscellaneous articles
  • Y10T428/31504—Composite [nonstructural laminate]
  • Y10T428/31678—Of metal
  • Y10T428/31681—Next to polyester, polyamide or polyimide [e.g., alkyd, glue, or nylon, etc.]

Definitions

• ABSTRACT This invention relates to a process for depositing a copper layer on a surface of a shaped article of a polyimide, which process comprises a. treating the surface with a solution of a noble metal salt and a halogenated alkanoic acid, and then drying the surface at an elevated temperature,
• steps (a) and (b) being carried out in either order, and then c. treating the surface with a solution containing a copper salt and a reducing agent.
• the invention relatesto a process for depositing copper layers on shaped articles of a polyimide.
• shaped articles of electrically non-conductive plastics for example polystyrene, acrylonitrile-butadiene-styrene copolymers (ABS plastics), polyolefms and polyesters, if necessary after a suitable pre-treatment, with thin metal coatings, the coating being carried out non-electrolytically or electrolytically.
• a coating process that has proved particularly successful involves depositing a very thin layer of noble metal nuclei on the plastic surface by sensitizing the surface with a noble metal salt solution and activating it with the solution of a reducing agent. Coherent metal layers then can be deposited on the noble metal nuclei by means of chemical or electrolytic metallization baths.
• the sensitizing pretreatment can be carried out, for example, by first treating the surface with a palladium salt solution, for example PdCland then with a hydrazine hydrate solution, whereupon small amounts of elemental palladium are deposited on the surface.
• a palladium salt solution for example PdCland
• a hydrazine hydrate solution whereupon small amounts of elemental palladium are deposited on the surface.
• the metal layers subsequently to be applied it is customary to roughen the plastic surface mechanically or, preferably, chemically, before the pre-treatment step described above.
• the chemical roughening may be effected, for example, with concentrated sulfuric acid which additionally can contain an oxidizing agent.
• Copending application Ser. No. 207,966, filed Dec. 14, 1971, provides a process for depositing a metal layer on a surface of a shaped article of a polyester, which process comprises a. sensitizing the surface with a noble metal salt solution,
• a metal salt solution e.g. a copper salt solution
• steps (a) and (b) being carried out in either order.
• the first of the steps (a) and (b) or each of both steps or at least step (a) is carried out with a solution additionally containing a halogenated alkanoic acid, preferably trichloroacetic acid, and, immediately after treatment with the solution containing halogenated alkanoic acid, the shaped article is dried with heating.
• a halogenated alkanoic acid preferably trichloroacetic acid
• the present invention provides a process for depositing a copper layer on a surface of a shaped article of a polyimide, which process comprises a. treating the surface with a solution which comprises a noble metal salt and a halogenated alkanoic acid, and then drying the surface at an elevated temperature,
• steps (a) and (b) being carried out in either order, and then c. treating the surface with a solution comprising a copper salt and a reducing agent.
• the invention makes it possible to provide shaped articles of polyimides with a firmly adhering copper coat- Polyimides which can be provided with a copper coating by the process of the invention include essentially all high molecular weight condensation products of aromatic diamines with dianhydrides of aromatic tetracarboxylic acids.
• aromatic diamines examples include 4,4'-diamino-dipheny-propane, 4,4- diamino-diphenylmethane, benzidine, 4,4'-diaminodiphenylsulfide, 4,4'-diamino-diphenylsulfone, 4,4- diamino-diphenyl-ether, m-phenylene-diamine, and pphenylenediamine.
• Suitable dianhydrides are, for example, the dianhydrides of the following tetracarboxylic acids: 2,3,6,7-naphthalene tetracarboxylic acid, 3,3',4,4'-diphenyl tetracarboxylic acid, bis-(3,4-dicarboxy-phenyl)-propane, bis-(3,4-dicarboxy-phenel)- ether and pyromellitic acid.
• the halogenated alkanoic acid is advantageously a chlorinated acetic acid, preferably trichloroacetic acid.
• a chlorinated acetic acid preferably trichloroacetic acid.
• other halogenated alkanoic acids for example 2,2,3-trichloropropionic acid or trifluoroacetic acid.
• the treatment solution which contains the haloge nated carboxylic acid preferably contains water as the solvent.
• the solvent also may consist of one or more organic liquids, for example acetone or butanone, or may be a mixture of one or more organic liquids with water.
• halogenated alkanoic acid especially trichloroacetic acid
• the amount of halogenated alkanoic acid, especially trichloroacetic acid, in the noble metal salt solution can vary very greatly. In general, solutions of about 5 to 25% by weight, preferably 10 to 15% by weight, are used.
• Noble metal salts which may be used include the salts of platinum, palladium, gold or silver.
• Palladium chloride which may be present in concentrations of between 0.001 and 5% by weight, preferably between 0.005 and 0.5% by weight, is preferred.
• the reducing agent is preferably tin-ll chloride, but it is also possible'to use an organic reducing agent, for example hydrazine hydrate.
• Tin-ll chloride may be used in aqueous solution containing hydrochloric acid, the concentration of the tin-ll chloride preferably being between 0.1 and 10% by weight, advantageously 0.5 to 5% by weight.
• Hydrazine hydrate may be used inalkaline aqueous solution, advantageously in concentrations of between 0.1 and 5% by weight, preferably of 0.5 to 1% by weight.
• the noble metal salt solution and the reducing agent solution may be allowed to act on the polyimide at room temperature for 10 seconds to 10 minutes, perferably 30 seconds to 3 minutes.
• the latter are preferably subjected to a cleaning process or surface hydrolysis in order to achieve uniform wetting by the treatment solution.
• Cleaning can be effected in a known manner with an organic solvent, or with an acid, or alkali.
• a particularly suitable agent for treating the surface is an aqueous solution which contains 1 to 5% by weight of chromic acid, 30 to 60% by weight of phosphoric acid and 30 to 50% by weight of sulfuric acid.
• the bath temperature is preferably between 50and C and the period of action is advantageously 5 to 15 minutes.
• the acid is rinsed off and the chromic acid which still adheres to the surface of the polyimide molding may be removed with an alkaline sodium thiosulfate solution. This avoids an uncontrolled local rection of the noble metal salt with remaining chromic acid when the sensitizing solution is applied.
• Shaped articles which may be copper plated by the process of the invention include all types of rigid polyimide moldings, for example those manufactured by injection molding. [t is, however, also possible to plate flexible shaped articles, for example fibers, filaments and films of polyimides by the process of the invention.
• the process of the invention is of particular advantage for the production of copper plated films, which find extensive industrial use, since naturally the adhesion of a metal layer presents a greater problem in the case of flexible films than in the case of rigid moldings.
• a substance which improves the wettability is preferably added, in known manner, to all the treatment solutions described above in order to achieve as uniform an action as possible.
• a small amount, for example 0.01 to 2%, of a water-soluble substance of high molecular weight, for example polyvinyl alcohol also may be added to the solution which contains the halogenated carboxylic acid.
• the content of wetting agent in the solution can in general be about 0.1 to 5% by weight. If a hydrazine hyrdrate or tin-ll chloride solution is used as the activating solution, it is not necessary to add a wetting agent to this solution.
• the molding is dried at elevated temperature.
• the temperature of the treated surface should not exceed 150C when a palladium salt solution containing a halogenated carboxylic acid is used; in general, a temperature of 120to 130C is used.
• the drying should not take place too rapidly since apparently a certain period of action of the treatment solution at elevated temperature is necessary if good adhesion of the copper layer to the substrate is to be obtained.
• the drying time is preferably 1 to 3 minutes, advantageously about 2 minutes.
• the drying can be carried out in hot air but also can take place under infrared radiators, for example.
• the copper can be deposited non-electrolytically on the surface from a copper salt bath containing reducing agents, i.e,, the surface is chemically metallized.
• any desired further thickening of the copper layer can be effected electrolytically or again non-electrolytically, in known manner.
• Electroplating baths with or without the addition of levelling and polishing agents are suitable for the electrolytic thickening of approximately 0.2 to 0.3 um thick copper layers deposited according to the invention.
• the deposition of copper in the electrolytic baths may be carried out at current densities of between 0.1 and 2 A/square decimeter.
• firmly adhering copper layers can be applied to a part of the surface or to the entire surface of the shaped article.
• films for example, can be copper plated on one side or on both sides.
• the adhesion of the copper layer to the substrate increases in the initial period after deposition of the metal and reaches its final maximum value after 1 to 3 days.
• the copper layers obtained according to the invention adhere so firmly to the substrate that, even if the copper plated shaped articles are stored for weeks in an atmosphere saturated with water vapor, their good adhesion is retained.
• a polyimide shaped article is subjected to the same treatment process as a shaped article treated by the process of the invention but without addition of a halogenated alkanoic acid to the noble metal salt solution, either no copper deposition takes place at all in the non-electrolytic bath (if the film has first been treated with palladium chloride and then with reducing agent), or copper deposition does take place in a nonelectrolytic bath (if the film has first been treated with reducing agent and then with palladium chloride), but after thickening of the non-electrolytically deposited layer in an electrolytic bath the thickened copper layer can be easily removed from the substrate. 1n the latter case the adhesion of the electrolytically thickened layers declines greatly within three days in air saturated with water vapor.
• copper plated polyimide films made by the process of the invention can be used, for example, for the manufacture of printed circuits.
• Printed circuits may be made from films which have been electrolytically thickened with copper or from the films which carry only the non-electrolytically deposited thin copper layer.
• EXAMPLE 1 A pm thick polyimide film of a polycondensate of diamino-diphenyl-ether and pyromellitic dianhydride was immersed for 7 minutes in an aqueous solution warmed to 70C which contained 1.7% of chromic acid, 49.0% of phosphoric acid, 40.0% of sulfuric acid and 9.3% of water as well as 0.005% of perfluorooctane carboxylic acid as the wetting agent.
• the film was then sprayed with water for 1 minute and immersed for 5 minutes in an aqueous solution, warmed to 40C, which contained 3% of sodium hydroxide and 1% of sodium thiosulfate.
• the film was again sprayed with water for 1 minute and was then immersed for 30 seconds at room temperature in an aqueous solution which contained 0.15% of palladium chloride, 0.25% of hydrogen chloride, 0.5% of polyvinyl alcohol of K-value 30 and 12% residual acetyl group content (Mowiol N 30-88 of Farbwerke Hoechst AG), 0.4% of sodium dodecylbenzene sulfonate and 13% of trichloroacetic acid.
• the treated film was fired for 2 minutes at C.
• the dried film was immersed for 30 seconds at room temperature in an aqueous solution which contained 0.6% of hydrazine hydrate and 1.25% of sodium hydroxide.
• the film was sprayed down and introduced for 2 minutes into a non-electrolytic copper bath warmed to 49C which had the following composition:
• a 0.29 am thick copper layer was deposited on the film surface.
• a cross-pattern of fine lines spaced about 1 mm apart was scratched in this layer by means of a razor blade and a pressure-sensitive adhesive tape was stuck over the pattern, no copper was removed from the substrate when the adhesive tape was abruptly pulled off.
• the copper layer was thickened to am over the course of 3 hours in an electrolytic bath having the composition shown below.
• the bath was at room temperature and l A per square decimeter current density was used.
• a stripping force for stripping the copper layer from the polyimide film (1 cm wide film strip) could not be measured in the peel test according to DIN 40,802 since when an attempt was made to separate the copper film from the polyimide film the latter plit before the copper layer tore.
• Example 1 aqueous solution which contained 0.15% of palladium chloride, 0.25% of hydrogen chloride, 0.5% of polyvinyl alcohol as in Example 1, 0.4% of sodium dodecylbenzene sulfonate and 13% of trichloroacetic acid.
• the treated film was dried for 2 minutes at 130C.
• the film was then immersed in the copper bath of Example l, warmed to 49C, for 2 minutes.
• the thickness of the copper layer was 0.24 am.
• Electrolytic thickening of this layer was carried out as in Example 1 until a layer thickness of 30 82 m was reached.
• the Table shows the test results for different sequences of the sensitizing solution (a) and the reducing solution (b) with and without the addition of trichloroacetic acid (TCA) to the solutions (a) and (b).
• TCA trichloroacetic acid
• a copper deposition in a non-electrolytic copper bath (0.2 to 0.3 pm) and adhesion of the nonelectrolytically deposited copper layer.
• EXAMPLE 2 A film as specified in claim I, which had been degreased and rinsed with alkaline sodium thiosulfate solution exactly as in Example 1. was activated for 5 minutes at room temperature in an aqueous solution which contained 0.5% by weight of tin-ll chloride and 0.7% by weight of hydrogen chloride.
• a process for depositing a copper layer on a surface of a shaped article of a polyimide comprises a. treating the surface with a solution ofa noble metal salt and ,about to 25% by weight of a halogenated alkanoicacid, and then drying the surface at a temperatu re in the range of about 120to 130C.
• steps (a) and (b) being carried out in either order, and then c. treating the surface with a solution containing a copper salt and a reducing agent.
• each of the treatment solutions used in steps (a) and (b) contains a wetting agent.
• step (a) contains about 0.01 to 2% by weight polyvinyl alcohol.
• step' (c) the thickness of the layer of copper is increased by electrolytic deposition of copper on the existing layer.
• polyimide is a condensation product of at least one aromatic diamine with at least one aromatic tetracarboxylic acid dianhydride.
• halogenated alkanoic acid is a chlorinated acetic acid.
• step (b) is tin-llchloride.
• step (b) is an aqueous solution, containing hydrochloric acid, of tin-ll chloride, the concentration of the tin-ll chloride being between 0.1 and 10% by weight.
• step (b) is an alkaline aqueous solution of hydrazine hydrate, the concentration of the hydrazine hydrate being between 0.1 and 5% by weight.
• the noble metal salt is a salt of platinum, palladium, gold or silver.
• step (a) contains 0.001 to 5% by weight of palladium chloride.

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

Applications Claiming Priority (1)

Publications (1)

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Family Applications (1)

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Cited By (15)

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Citations (7)

• 0
  • BE BE792310D patent/BE792310A/fr unknown
• 1971
  • 1971-12-08 DE DE2160821A patent/DE2160821C3/de not_active Expired
• 1972
  • 1972-11-28 NL NL7216124A patent/NL7216124A/xx unknown
  • 1972-12-05 US US31227272 patent/US3881049A/en not_active Expired - Lifetime
  • 1972-12-05 GB GB5607872A patent/GB1403219A/en not_active Expired
  • 1972-12-05 AT AT1033772A patent/AT322320B/de not_active IP Right Cessation
  • 1972-12-06 IT IT5450572A patent/IT973915B/it active
  • 1972-12-06 JP JP12237972A patent/JPS4866168A/ja active Pending
  • 1972-12-06 CA CA158,211A patent/CA990593A/en not_active Expired
  • 1972-12-07 FR FR7243524A patent/FR2162526B1/fr not_active Expired

Patent Citations (7)

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