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
  • C23C18/42—Coating with noble metals
  • C23C18/44—Coating with noble metals using reducing agents
• • 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
  • C23C18/1601—Process or apparatus
  • C23C18/1633—Process of electroless plating
  • C23C18/1646—Characteristics of the product obtained
  • C23C18/165—Multilayered product
  • C23C18/1651—Two or more layers only obtained by electroless plating
• • 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
  • C23C18/1601—Process or apparatus
  • C23C18/1633—Process of electroless plating
  • C23C18/1655—Process features
• • 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
  • C23C18/1601—Process or apparatus
  • C23C18/1633—Process of electroless plating
  • C23C18/1675—Process conditions
  • C23C18/1683—Control of electrolyte composition, e.g. measurement, adjustment
• • 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
  • C23C18/52—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 using reducing agents for coating with metallic material not provided for in a single one of groups C23C18/32 - C23C18/50

Definitions

• the invention relates to a method for electroless metal deposition.
• the layer thickness is not always as uniform at all points as is desirable for the economic utilization of the metal salts contained in the baths.
• two or more sub-baths - one with the metal salt, a second with the necessary reducing agent, optionally further with additives such as complexing agents, stabilizers and / or brightening agents - are sprayed simultaneously but separately in order to separate the metal before it hits it to avoid coating the substrate surface.
• additives such as complexing agents, stabilizers and / or brightening agents -
• a macroscopically uniform metal coating is created, which, however, has a granular structure in the micro-range in which the layer thicknesses in neighboring micro-ranges can differ from one another by a multiple.
• the quality of each metal coating is usually determined by the points with the smallest layer thickness; To achieve an overall satisfactory coating quality, considerably more metal coating bath is therefore used. corresponds to the necessary minimum layer thickness.
• the amount of metal which is unnecessarily deposited at the locations with a high layer thickness means a considerable loss.
• the object of the present invention was to provide a method for electroless metal deposition by spraying a metal deposition bath, in which the metal is deposited in a layer thickness that is as uniform as possible.
• a very uniform metal layer can be produced by spraying an aqueous metal deposition bath onto a substrate surface if the metal deposition bath is diluted with water at the moment it hits the substrate surface.
• the rate of separation is essentially determined by the concentrations of the reactants in the sprayed droplets that unite. If the concentration is reduced by the addition of water at the moment of impact, the time until the metal deposition begins is longer. During this time, the sprayed-on droplets can be thoroughly mixed so that the metal deposition does not begin in a punctiform manner, but rather in the form of a very thin but closed layer.
• the same effect is achieved if initially very dilute solutions of the metal salt partial bath and the reducing agent partial bath are sprayed on through separate nozzles to form a well-mixed, highly diluted metal deposition bath.
• the invention thus relates to the process for the electroless deposition of a uniform metal layer by spraying a metal deposition bath containing a metal salt and a reducing agent and possibly further additives onto a substrate surface, which is characterized in that by reducing the bath concentration, a coherent thin metal coating is first produced on the substrate surface is, which is strengthened by subsequent treatment with a deposition bath of conventional concentration to the desired thickness.
• the method according to the invention can in principle be used with all metal coatings which are usually deposited without current. Since it enables significant savings on metal salts, it is preferred for the application of precious metal layers, for example made of gold, silver, platinum or palladium.
• the customary reducing agents can be used for each metal to be deposited by the process according to the invention, for example hypophosphite for gold, formaldehyde, sugar or sugar derivatives for silver, hydrazine hydrate for platinum or palladium.
• the process according to the invention can be used wherever a conventional aqueous metal deposition bath is sprayed onto a substrate surface.
• the dilution step according to the invention can be carried out in various ways.
• the metal deposition bath can be sprayed into a possibly moving thin water layer on the substrate surface, the amount of water being selected such that the concentration of the bath or at least the metal salt sub-bath is 50 to 5 at the moment the spray jet hits the water layer % of the concentration in the spray jet is reduced.
• the method according to the invention is applied to the metal deposition systems customary in practice, where the substrate is moved on a conveyor belt under a number of spray nozzles arranged one behind the other in the direction of movement of the conveyor belt, the beam with the spray nozzles moving transversely to the direction of movement of the Conveyor belt moved back and forth over the substrate.
• pure water is sprayed from the first nozzle - as seen in the direction of movement of the conveyor belt - under such a pressure that a water wave forms when it hits the substrate, which, depending on the transport speed of the belt and the spraying agent, has its greatest amplitude runs a short distance in front of the spray cone.
• the second and possibly further nozzles or pairs of nozzles, from which the metallization bath, optionally also in the form of partial baths, is sprayed, are then set such that their spray cones are partially coexistent. that of the water nozzle overlaps, the center of the spray cone of the second nozzle or pair of nozzles being set approximately above the highest point of the water wave running in front of the first spray cone. However, it may also be expedient to set the spray cone of the water nozzle (s) so that it completely overlaps with the spray cone (s) of the first nozzle or the first pair of nozzles.
• the metal deposition bath is sprayed in the form of two partial baths from the second and third nozzle or the second and third pairs of nozzles, these are adjusted so that their spray cones fully meet on the substrate surface.
• the two partial baths are then alternately sprayed from further nozzles or pairs of nozzles so that the spray cones partially overlap.
• the concentration of the metal deposition bath on the substrate with the pre-transport is gradually increased until after passing through the last nozzle the bath concentration corresponding to the desired layer thickness has been reached.
• the substrate surface is then freed from the bath residues and residues in a conventional manner by rinsing with water.
• the metal deposition bath can be sprayed in a completely mixed form - this is possible, for example, in cases where the metal deposition is only catalyzed by an activator located on the substrate surface - it is advantageous to use a diluted one from the second nozzle and from the third and to spray more and more concentrated baths in the following nozzles.
• a concentration gradient forms on the substrate in the direction of movement, which leads to a particularly uniform metal coating.
• the spray pressure and spray angle of the nozzles are preferably set such that the initial concentration of the metal deposition bath on the substrate surface is 50 to 5%, in particular 10 to 30% of the maximum concentration.
• a system for the production of silver mirrors consists of a 140 cm wide conveyor belt on which cleaned and activated with a tin (II) salt solution in a known manner glass plates are transported at a speed between 100 and 260 cm per minute under a nozzle bar, which in 20 - 40 cm height above the conveyor belt makes 18 back and forth movements per minute across the entire width.
• nozzle bar 4 pairs of nozzles are arranged one behind the other in an angle-adjustable manner (nozzles 1 - 4), from which the metal deposition bath or the partial baths can be sprayed under a pressure of 3 to 6 bar.
• a further angle-adjustable nozzle with twice the capacity is attached to the nozzle bar, from which additional water can be sprayed onto the glass plates that are transported past on the conveyor belt.
• aqueous ammoniacal silver nitrate solutions were used in concentrations of 0.5 to 3.5% and in each case equivalent amounts of a commercially available reducing agent (R) based on a sugar derivative. These solutions are sprayed through the paired nozzles onto the glass plates that are moving past. After every 2 minutes, measured from the impact of the first spray jet on the activated glass, it is rinsed with pure water through subsequent nozzles and dried. The mirrors obtained were assessed by determining the amount of silver deposited per unit area (mean value with spread). In some runs, according to the invention, water was sprayed on beforehand, in others according to the prior art, without this measure. The results are summarized in the following table:
• the table clearly shows that by additionally spraying water through the nozzle W (runs 5 to 8), the initial bath concentration on the glass plates rose from 3.5% to about 1.5% and from 1.75% to about 0 , 15% is reduced, much more uniform silver levels are obtained than without this measure.
• This can also be clearly seen when looking at the silver mirrors produced in transmitted light, where the silver layers obtained in runs 1 to 4 clearly show a granular structure which is not recognizable in the runs 5 to 8 produced.
• the adhesive strength of the silver layers with the granular structure is significantly lower; here the silver layer can be removed by scratching with the fingernail, while this is not possible with the silver layers produced in runs 5 to 8.

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• 1980
  • 1980-03-28 DE DE19803012006 patent/DE3012006A1/de not_active Withdrawn
• 1981
  • 1981-02-19 EP EP81101169A patent/EP0036940B1/fr not_active Expired
  • 1981-02-19 DE DE8181101169T patent/DE3164947D1/de not_active Expired
  • 1981-03-26 JP JP4327981A patent/JPS56150176A/ja active Pending
  • 1981-03-27 BR BR8101866A patent/BR8101866A/pt unknown
  • 1981-03-27 ES ES500790A patent/ES8205268A1/es not_active Expired
  • 1981-03-27 FI FI810947A patent/FI66437C/fi not_active IP Right Cessation

Patent Citations (3)

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