JPH0239474B2 - - Google Patents

Description

[Detailed description of the invention]

INDUSTRIAL APPLICATION FIELD OF THE INVENTION The present invention relates to a method for directly adhering metal plating to the surface of a ceramic substrate, and more particularly to an improved method for directly bonding to the surface of a ceramic substrate to form a printed circuit. Prior Art Metal-plated conductor patterns on ceramic substrates have been widely used in the electronics industry. For many years, ceramics have been metal plated using high cost methods such as molten metal-glass pastes and thin film vacuum deposition techniques. Attempts to reproducibly create circuit patterns by direct electroless plating have been unsuccessful due to poor adhesion of the metal film to the substrate and reproducible and uneven surface coverage. Printed circuits on ceramics containing alumina were already published in 1947. One system, known as thin film circuitry, consists of a thin film of metal deposited onto a ceramic substrate by a type of vacuum plating technique. In this method, a chromium or molybdenum film with a thickness of about 0.02 microns serves as a binder for the copper or gold conductors. Photolithography is used to create high resolution patterns etched from thin metal films. Such conductive patterns can be electroplated up to 7 microns thick. Due to high cost, thin film circuits have been limited to high frequency and military applications requiring high resolution patterns. Another type of printed circuit, known as a thick film circuit, consists of metal and glass films baked onto a ceramic substrate. Typically, the membrane has a thickness of about 15 microns. Thick film circuits have been widely used. Thick films are made by screen printing circuit patterns with pastes containing conductive metal powder and glass frit in an organic carrier. After printing, the ceramic part is fired in a furnace to burn off the carrier and sinter the conductive metal particles.
The glass is melted, thus forming a glass-metal particle conductor. The electrical conductor is firmly bonded to the ceramic by the glass, and the components can then be connected to the electrical conductor by soldering, wire bonding, or the like. The conductors in thick film circuits have only 30 to 60 percent the conductivity of pure metals. The high conductivity of pure metals is required to provide interconnects for high speed logic circuits. Because the electrical conductors of thick film circuits do not have such high conductivity, they do not provide optimal interconnection for high speed logic circuits. The minimum conductor width and minimum conductor spacing obtained by screen printing and baking in a particularly high quality manner are 125 and 200 microns, respectively.
However, under normal manufacturing conditions, these minimum values are 200 and 250 microns, respectively. Multilayer techniques are used for ceramic circuits requiring high interconnect density or high connectivity. In the thick film multilayer process, a first layer of metal powder and gas frit is printed onto a ceramic substrate and heated in a furnace.
Typically, it is baked at 850℃. An insulating dielectric layer is then screen printed over the conductor pattern, leaving only the points exposed where contact will be made to the next metal plating layer. This dielectric pattern is also baked at 850°C. Then the second
dielectric layer is printed and baked. The two dielectric layers must be printed and baked to ensure there are no pinholes. After the two dielectric layers are printed and baked, the next conductor layer is printed and baked to make contact with the underlying conductor layer, if necessary, through apertures left in the dielectric layer. A typical multilayer ceramic package includes two to six metal plating layers. Eight layers are not uncommon. Due to the two-layer metal plating, the substrate is
Printed twice and baked four times at 850℃. For three-layer metal plating, the substrate is printed seven times and baked at 850°C. and 4
For thick film multilayer ceramic layers, it is 10 times. According to the method of the invention, the same connectivity as in multilayer ceramics with three or four layer films can be achieved with conductor patterns plated through holes on one and both sides. In order to achieve high conductivity in ceramic-based circuit patterns, attempts have been made to bond pure metal conductors directly to ceramic substrates containing alumina. (See U.S. Pat. No. 3,744,120 and U.S. Pat. No. 3,766,634). No. 3,994,430 and others describe methods for bonding copper sheets to alumina by heating the copper in air and forming an oxide film on the surface. The copper sheet is then bonded to the alumina through this coating in a nitrogen furnace at a temperature between 1065°C and 1075°C. In order to obtain a well-adhered copper foil without bubbles: (1) the copper foil must be carefully oxidized until a black surface; (2) the thickness of the copper oxide must be carefully controlled; (3) The amount of oxygen in the copper foil must be regulated; (4) the amount of oxygen in the nitrogen furnace must be kept at a regulated level to maintain a very mild oxidizing atmosphere; and (5) the temperature must be kept at 1 Must be adjusted within %. This ultra-high temperature operation not only makes the equipment expensive, but also makes it difficult to operate and control. If the very tight controls described above are not maintained, air bubbles and other poor adhesion of the copper foil to the substrate will clearly occur. Despite the difficult operating conditions, these methods are being introduced into commercial applications due to the demand for metal plated products. Although the above-mentioned systems are used commercially,
The simple metal plating of ceramics with pure metal conductors such as copper inspired a series of patents and proposed processes. See, for example, German Patent No. 2004133, German Patent No. 2453192, German Patent No. 2453277 and German Patent No. 2533524. See also US Pat. No. 3,296,012, which discloses a method of creating a microporous surface for non-electroplating alumina. Attempts to simply apply electroless metal plating directly to ceramic substrates have continued, but have never been commercially successful. Even toxic and corrosive substances such as hydrogen fluoride were tried to bond metals directly non-electrically without extreme baking temperatures (J.Electrochem.Soc. 120 , 1518 (1973)). . However, hydrogen fluoride etching weakened the strength due to excessive attack on the ceramic surface. Another attempt, disclosed in a US patent, involves sensitizing the surface with a stannous chloride sensitizer, activating the surface with palladium chloride, and first etching the ceramic surface before non-electroplating the surface. molten sodium hydroxide.
Although sodium hydroxide etching provided good bond strength to the metal film, commercial production was also not achieved. The problem was poor surface coverage of non-electrodeposited metal. Although metal deposition typically covered 90% or more of the surface area, this was insufficient. Any defect in the metal film will result in an open circuit or complete lack of operation if the defect occurs in the fine wire conductor pattern. US Pat. No. 4,428,986 discloses a method for the direct autocatalytic plating of metal coatings onto Beryllium. This method involves preparing beryllia at 50°C at 250°C.
% sodium hydroxide solution for 7 to 20 minutes, rinse with water, etch the surface of the Berilya substrate with fluoroboric acid for 5 to 20 minutes, rinse with water, and add 5 g/l of dichloride. Soak beryllia in tin solution and 3N hydrochloric acid, wash with water,
It consists of treating beryllya with a 0.1 g/palladium chloride solution, washing with water and then electrolessly plating nickel onto beryllya. However, the etching step removes silica and magnesium from the grain boundaries of beryllya, weakening the beryllia surface. As a result, this method allows only a small amount of damage before the Beryllium substrate breaks down.
Only achieves a bond strength of 250 pounds per square inch (1.7 MPa). This coupling strength is small, about one third of the coupling strength typical of thick film circuits. Other methods of forming printed circuit patterns on ceramic substrates are described in U.S. Pat. No. 3,772,056;
No. 3772078, No. 3907621, No. 3925578, No.
No. 3930903, No. 3959547, No. 3993802, and No. 3994727. However, these patents do not teach how to solve the problem of poor surface coverage and inadequate bond strength of ceramics. Ceramic packages have been widely used to protect microelectronic circuits, such as integrated circuits and hybrid circuits, from contamination from the outside environment. A hermetic seal is required between the ceramic substrate of the package and its cover to exclude the outside environment. To date, hermetic seals have been provided for ceramic dual-in-line packages used in the microelectronic industry by the following method. In one method, refractory metal paste,
Usually molybdenum-manganese based pastes are applied to ceramic substrates. The paste and ceramic substrate are baked at 1500-1800°C in an inert or reducing atmosphere to fuse the molybdenum-manganese alloy to the ceramic surface. A refractory metal alloy is then plated with gold or nickel and gold. The microelectronic circuit is inserted into the ceramic cavity through an opening in the substrate. Microelectronic circuits are connected to fill the holes provided in the substrate. The opening in the ceramic body is hermetically sealed by placing a soldered cover over it. A gilded Kovar lid or a ceramic lid with a gilded molybdenum-manganese alloy surface is used as the cover. Soldering is performed using gold-tin solder or tin-silver-antimony solder in a nitrogen atmosphere.
In this case, a good hermetic seal can be produced, but the disadvantage is that the cost is extremely high due to the difficulty of plating the refractory metal and the extremely high baking temperatures. Epoxy adhesives have also been used to provide a seal between the ceramic package and the package lid. This method is unsatisfactory because organic vapors from the epoxy sealant can contaminate the microelectronic circuits. Yet another method of forming a hermetic seal for a ceramic package is to use a low melting point glass applied as a glass paste with a carrier solvent. The glass paste is applied to the sealing surface of the ceramic package and then melted in a furnace. This method is unsatisfactory because it encapsulates the solvent from the glass paste inside the package as well as some of the glass itself. The high reliability of the circuit can be destroyed due to contamination by solvents trapped within the glass interlayer. OBJECT OF THE INVENTION The object of the present invention is to apply a metal film to a ceramic substrate to provide an excellent surface coverage and a pressure of at least 3 MPa.
Preferably it is to provide a method for obtaining a bond strength of at least 5 MPa. It is an object of the present invention to create a metal-plated ceramic substrate that can be used in fine line circuit applications with high purity metal conductors. An object of the present invention is to provide a method for forming a metal film with good adhesion on a ceramic substrate by electroless plating, thereby making it possible to form an electrical conductor directly bonded to the ceramic substrate. It is an object of the present invention to provide a plated ceramic substrate and a method of making a plated substrate with electrical conductors suitable for interconnection for high speed logic circuits. It is an object of the present invention to provide a double-sided plated ceramic substrate with a through-hole conductor pattern and conductor density comparable to three or four layer thick film multilayer ceramics. It is also an object of the present invention to provide a method for joining ceramic articles or other plated ceramics by soldering, brazing or welding. It is an object of the invention to provide a hermetic seal for ceramic articles. SUMMARY OF THE INVENTION The present invention is directed to a method of forming a metal coating on a ceramic substrate containing alumina, which provides excellent surface coating and bond strength (i.e. at least
3 MPa, preferably at least 5 MPa). The invention also includes ceramic substrates having printed circuit patterns produced from such films. The process of the invention can also be used to treat ceramic substrates for electroless or electrolytic metal plating. At least 0.2 on ceramic substrate
A metal deposit having a thickness of microns, preferably at least 2 microns, is obtained, which typically has a conductor shape having a width of no more than 25 microns, preferably 50 microns. The process of the invention consists of the following steps: (a) treating the surface of the ceramic with at least one molten inorganic compound to enhance adhesion; (b) treating the treated surface with at least one molten inorganic compound; , contact with an accelerator solution which promotes the adsorption of the catalyst; then (c) after the surface has been treated to sensitize or catalyze it for plating; (d) the so treated ceramic surface is metal plated. In other embodiments, the process of the invention also includes bonding metal-plated ceramic substrates to metals by soldering, brazing, or welding, or
It also includes bonding with other metal-plated ceramic substrates. In accordance with the present invention, any metal film can be deposited on the surface of the ceramic substrate. Typically, metal films of copper, nickel, silver or cobalt are electrolessly plated. The ceramic surface is first treated at high temperatures with a substance that provides the etched surface necessary to create a strong bond between the deposited metal layer and the ceramic substrate. Preferred materials for this purpose are at least one alkali metal compound in the molten state. Preferred alkali metal compounds include sodium hydroxide, potassium hydroxide, sodium carbonate and potassium nitrate, and potassium hydrogen sulfate. Methods proposed for etching with molten alkali are shown in US Pat. No. 3,690,921 and others, all of which describe a method of heating sodium hydroxide to a temperature of 450°C. Many alkali metal compounds are suitable for promoting adhesion of ceramics, such as etching. Preferably, compounds with low melting points are used. Alternatively, the melting point of the alkali metal compound may be lowered by dissolving up to about 50% by weight, preferably 20% by weight, of a low melting point substance or liquid in the alkali metal compound. Examples of such melting point lowering agents include stannous chloride, nitric acid,
It is believed to include water, sodium and potassium formate, potassium acetate, Rothsiel's salt, borax, and hydrates of lithium bromides, iodides and phosphates, and potassium pyrophosphate. At times it may be preferable to avoid hydroxides for safety and ease of neutralization. Representative alkali metal compounds suitable for use in the present invention and their melting points are reported in Lange's Chemistry Handbook, 11th edition (1972), and are as follows.

Table: Eutectic mixtures such as a mixture of potassium hydroxide and sodium hydroxide or a mixture of sodium carbonate and potassium nitrate can also be used to etch the substrate. The former type of mixture is preferably KOH
The weight ratio of HaOH to HaOH is 59:41, and it has a melting point of 170°C. Typical ceramic substrates etched by the molten compounds used herein are alumina, silicates, beryllia, titanates, forsterites, mullite, steatite, porcelain and mixtures thereof. Typical metal plating solutions used are electroless plating solutions such as nickel, cobalt, gold and copper (see, for example, US Pat. Nos. 3,485,643, 3,607,317 and 3,589,916). Electroplating solutions are also used in the practice of this invention. In the method described by Elmore, the sodium hydroxide is washed from the ceramic surface with water, the ceramic surface is then neutralized with dilute sulfuric acid, and after another wash with water,
The surface is sensitized with stannous chloride, washed with water and seeded with palladium chloride to catalyze it for electroless metal plating. This method is unreliable and often results in incomplete surface coverage due to non-electronically generated metal deposits. This condition is completely impractical. With prolonged immersion in both the stannous chloride sensitizer solution and the palladium chloride seeding solution, and with an incomplete water wash step, it is sometimes possible to obtain complete surface coverage with metal. However, this stage is not practical for production. Prolonged immersion in the sensitizer hinders the economical performance of the work, and incomplete water washing after stannous chloride leads to poor adhesion formed in the seeding solution and in the electroless plating solution. This results in precipitated particles and rapid decomposition of these solutions. The use of a single catalyst solution prepared from both stannous chloride and palladium chloride is well known in the art of printed circuitry and plating on plastics. A typical catalyst solution is described in U.S. Patent No.
No. 4,187,198 and US Pat. No. 3,961,109. Such a catalyst solution can be used more advantageously in ceramic plating than the two-stage sensitized seeding solution described by Elmore. We have demonstrated that the adsorption of agents that render the surface receptive to metal plating, i.e., sensitizers, seeders, or catalysts, and at the same time that the surface coverage by metal plating makes the etched ceramic surface more susceptible to certain compounds. It has been found that this can be greatly enhanced by treatment with This compound is adsorbed onto the ceramic surface, promoting the adsorption of the sensitizer over the entire surface and, surprisingly, allowing its complete coverage. Compounds of this type include single chlorides, bromides and iodides and complexes of chlorides, bromides and iodides. The invention is further illustrated by describing the use of acidic chloride, bromide and iodide solutions greater than 0.5 molar as the halide to promote uniform adsorption onto ceramic surfaces. These acid halide solutions do not attack the glass phase of the ceramic substrate. Acidic chloride, bromide or iodide solutions can be used as pre-treatment or pre-soak solutions after adhesion promotion, washing, neutralization and re-washing; and before treatment with e.g. stannous chloride sensitizers. can. It has been found that after such pretreatment, the sensitizer is rapidly adsorbed onto the etched ceramic substrate. Immersion in the sensitizing solution need not be unduly prolonged. Furthermore, the tin species are so reliably adsorbed that they are not inadvertently removed even during conventional water washing steps. The acidic chloride, bromide or iodide presoak or pretreatment solution is preferably greater than 2 moles as halide ions, more preferably greater than 3 moles as halide ions. The acidity of the halide solution is preferably as hydrogen ions
More than 0.001 moles, more preferably more than 0.01 moles as hydrogen ions, most preferably between 0.1 and 12 moles as hydrogen ions. Separately, the inventor has realized that the chloride, bromide or iodide concentration of the sensitizer solution may be increased to achieve a similar effect, i.e. stronger adsorption of the sensitizer onto the ceramic substrate. I found it. High acidity prevents adsorption of tin sensitizers. The halide to acid ratio in the stannous ion sensitizer is preferably at least 15:1. Lower ratios of halide to acid, such as a 2 to 1 ratio, can be used, but are not preferred because they require high tin concentrations, ie, 1 mole of tin. Although we do not wish to be bound by theory, in the case of tin-containing solutions, the tin species adsorbed onto the alumina are tetrahalostannate moieties. For example, high chloride ion concentrations relative to acidity favor the formation of tetrachlorostan()ate, and conversely, high acid concentrations favor the formation of trichloro and dichlorostan()ate complexes. For example, Stability Constants of Metal Ion Complexes, Spec.pub 17, Sillen and Martel,
The Chemical Society, London (1964) 296~
See page 7. When using a single catalyst solution consisting of chlorides, bromides, or iodides of palladium, tin and halides, acidic or alkali metal halide salts without an acidic halide presoak solution, the halide concentration is from 0.5 It may vary in the range of 6 mol/, but preferably more than 1.5 mol/, preferably less than 4 mol/. The acidity is
It may vary from 0.03 to 6 mol/, preferably more than 0.3 mol/, preferably less than 4 mol/. To increase processing latitude and minimize processing errors, acid halide pretreatment may be combined with a sensitizer solution formulated with halide and acid concentrations according to the invention. Additionally, acid halide presoaks may also be used with a single catalyst solution. By using an acidic halide pre-soak, other catalytic noble or semi-precious metals can be adsorbed onto the ceramic surface, including Group 1A metals, silver and gold, and other Group noble metals. Numerous processes are used to manufacture printed circuit boards. As will be readily understood by those skilled in the art, these printed circuit manufacturing processes can also be combined with the adhesion promotion step of the present invention to produce metal-plated ceramic printed circuit boards. may be used in combination with the step of making it acceptable. In accordance with the present invention, articles and methods are formed that provide a hermetic seal of a metal layer to a ceramic substrate.
The present invention provides a hermetically sealed ceramic package for microcircuit and other applications. Additionally, the process of the present invention provides a method for applying an adhesive metal film to a ceramic surface, which film is bonded to the metal-plated ceramic surface by standard metal bonding techniques such as soldering, brazing, and welding. or can be used to bond metal-plated ceramic surfaces to metal articles. "Hermetic Seal" as used throughout this specification
(hepmetic seal) is a MIL-STD-
883B, Method 1014.3 (May 16, 1979). As those skilled in the art will appreciate, these hermetic seals are suitable for hybrid packages, chip carriers, integrated circuit packages, flat packages, dual-in-line packages, and optoelectronic packages. In forming a hermetic seal on a ceramic substrate according to the process of the present invention, the surface of the ceramic substrate is first provided with a metal layer by the method described above. The metal layer on the ceramic surface is then bonded to the metal or other metal-plated ceramic substrate by standard metal bonding techniques, typically soldering. Other embodiments of carrying out the invention are disclosed inter alia in the examples. Example This example shows how a pre-soak containing chloride or bromide provides uniform surface coverage. 0.5 containing 90% alumina (the rest is other oxides)
mm thick flat black ceramic substrates are commercially available from BASF-Wyandotte using an alkaline cleaning solution.
Adhesion is promoted by immersion in Altrex for 10 minutes at a temperature of 60°C. The substrate was then washed with water at 25° C. for 1 minute, immersed in sodium hydroxide solution (760 g/), taken out, and drained. The resulting wet ceramic substrate is placed on the edge of the support fixture. Next, the substrate was dried at 175°C for 10 minutes to remove moisture in the sodium hydroxide film on the substrate, and then heated in a furnace at 450°C for 15 minutes to melt the sodium hydroxide and roughen the surface. Promotes adhesion. After cooling for 5 minutes, the ceramic substrate was rinsed with water, rinsed in 20% sulfuric acid for 2 minutes at 25°C, and then rinsed in deionized water for 25 minutes.
Rinse for 2 minutes at °C. After this adhesion promoting operation, the ceramic substrate was electrolessly plated with an adhesive copper film in the following manner. (a) Soak for 2 minutes at room temperature in the chloride or bromide presoak solution shown in Table 1. (b) Immersion for 10 minutes at room temperature in a sensitizer solution consisting of 59 g of stannous chloride dissolved in 1 part of a 0.12 molar hydrochloric acid solution. (c) Rinse with deionized water at room temperature. (d) Immersion for 2 minutes at room temperature in an activator solution of 0.1 g palladium chloride dissolved in 1 part 0.012 molar hydrochloric acid. (e) 30 minutes at room temperature in an electroless copper bath consisting of 10 g copper sulfate / 17 g ethylenediaminetetra-2-hydroxypropanol / 6 g formaldehyde / 10 mg block copolymer wetting agent / 10 mg sodium cyanide / brought to pH 13 with sodium hydroxide. Metsuki. The effect of halide pre-soaking on the surface coating of ceramic substrates is shown in Table 1.

Table: Unacceptable coating means copper deposits with good color and adhesion but with some skipped plating or bare spots. By complete metal coating we mean a copper coating with good color and adhesion and complete coverage with no bare spots or skipped plating. In all cases, even with incomplete surface coverage,
Adhesion of metal to ceramic was excellent. EXAMPLE This example shows the effect of the PH of the halide pre-soak solution. The method of the example was repeated except that the halide pre-soak solutions and the results obtained are shown in the table.

[Table] Less Example The method of Example was repeated except that the halide was omitted and the sensitizing solution in step (d) was modified with sodium chloride. The sensitizer solution was: 50 g of stannous chloride / 8 ml of hydrochloric acid / 180 g of sodium chloride / When a ceramic substrate was plated in the electroless copper bath of the example, complete copper was deposited on the ceramic substrate without any voids. It became something with a membrane.
That is, by increasing the chloride concentration in the sensitizer solution compared to the example, complete coverage of the ceramic substrate with a copper film is achieved without the use of a separate halide pre-soak solution step. . EXAMPLE This example further illustrates the importance of halide concentration in the pretreatment step of ceramics prior to electroless plating. Ceramic substrates are adhesion promoted in the manner described in the examples. A catalyst concentrate was prepared according to the method disclosed in US Pat. No. 3,961,109. An aqueous solution containing palladium chloride, stannous chloride, sodium chloride, hydrochloric acid and resorcinol is prepared and heated. After cooling, the solution was diluted with additional sodium chloride, stannous chloride, and hydrochloric acid to obtain a standard concentrated catalyst solution. 31 ml of this concentrated solution was diluted to 1 to obtain a catalyst solution for actual use. For catalyst solutions with high chloride content, 31 ml of concentrate was diluted with a solution of 3.8 molar sodium chloride, 0.11 molar hydrochloric acid and 0.025 molar stannous chloride. For catalyst solutions with low chloride content, 31 ml of the concentrate was diluted with 0.18 molar sulfuric acid solution. Two catalyst solutions with intermediate chloride concentrations were prepared by diluting 31 ml of the concentrate with a 0.36 molar hydrochloric acid solution and a 0.36 molar hydrochloric acid solution with 1 molar sodium chloride, respectively. These four types of catalyst solutions had the following compositions.

【table】

[Table]
Sulfuric acid 0 0 0 1
8

Claims (1)

[Scope of Claims] 1. A method in which the surface of a ceramic substrate is metallized by treating the surface to accept metal with good adhesion and metal plating the treated surface, the surface being treated with one or more alkalis. The surface of the melt is treated with a molten material containing a metal compound, and the surface thereof is treated with a molten material containing at least one halide selected from the group consisting of chloride, bromide, and iodide, and having an acidity of 0.001 mol/ml by hydrogen ions.
The above surface is exposed to an acidic halide solution having a halide concentration of 1.5 mol/min or more, and the surface is further treated with a catalyst solution to render it receptive to metal plating, and the surface thus treated or 1. A method of metallizing a ceramic substrate surface, comprising exposing selected portions of the surface to a metal plating bath solution to form a uniform metal layer on the surface or selected portions thereof. 2. The method according to claim 1, wherein the acidic halide solution has a halide ion concentration of 3 mol/min or more. 3 The above acidic halide solution is hydrogen ion.
2. A method according to claim 1, having an acidity of 0.01 mol/mole or more. 4 The acidic halide solution forms part of the catalyst solution used to render the surface receptive to metal deposition, and the catalyst solution contains 1.5 halides.
A method according to claim 1, containing ~6 mol/containing and having an acidity of 0.03 to 6 mol/. 5. The method of claim 4, wherein the catalyst solution contains a halide in a proportion of 4 mol/less or less. 6. The method of claim 4, wherein the catalyst solution has an acidity of 0.03 to 4 mol/ml. 7. The method of claim 1, wherein said alkali metal compound is selected from the group consisting of hydroxides, carbonates, nitrates, hydrogen sulfates, and mixtures thereof. 8. The method according to claim 1, wherein the melt further contains at least one substance that adjusts the melting point of the alkali metal compound. 9. The method according to claim 1, wherein the melt further contains at least one substance that adjusts the melting point of the alkali metal compound in a proportion of 20% by weight or less. 10. The method of claim 1, wherein said alkali metal compound is selected from carbonates, nitrates and mixtures thereof. 11. Claim in which the acidic halide solution is selected from hydrochloric acid, hydrobromic acid and acidic alkali metal halide solutions, the alkali metal is selected from sodium and potassium, and the halide is selected from bromide, chloride and iodide. The method described in Section 1. 12. The method of claim 1, wherein the acidic halide solution further contains stannous chloride. 13. The method of claim 1, wherein the acid halide solution comprises stannous chloride and is used as a sensitizer solution prior to treating the surface with a seeding solution selected from noble metal containing solutions. 14 The above acidic halide solution is tin chloride ()
5. A method according to claim 4, comprising a mixture obtained by reacting a noble metal halide with a noble metal halide to form a compound suitable for rendering said surface receptive to electroless metal plating. 15. The method of claim 1, wherein the surface is treated with an acidic halide solution selected from bromide, chloride and iodide and then further treated with a silver nitrate solution to render the surface receptive to electroless metal plating. 16. Claim 1, wherein the surface is treated with an acidic halide solution selected from bromide, chloride and iodide and then further treated with a silver nitrate solution which forms silver halide which is reduced to metal by light or a reducing agent. the method of. 17 A first metal layer is formed electrolessly, and this layer is further coated with 1 by electroless plating or electroplating.
2. The method of claim 1, wherein the metal is plated. 18. The method according to claim 1, wherein the alkali metal compound is heated to 150°C or higher. 19. The method according to claim 1, wherein the alkali metal compound is heated to 300°C or higher. 20. The method according to claim 1, wherein the alkali metal compound is heated to 600°C or higher. 21. The method of claim 1, wherein the acid halide solution is used as a pretreatment step prior to the catalytic step, and the ceramic substrate proceeds from this pretreatment step to the catalytic step without being washed. 22. A method of metal plating a ceramic substrate surface comprising treating the surface to accept metal with good adhesion and depositing the metal on the treated surface, the surface being coated with a melt containing one or more alkali metal compounds. to provide the surface with an electrically conductive connector area for connection in subsequent electroplating, with a halogen selected from the group of chlorides, bromides or iodides, having an acidity of from 0.03 to 6 mol/ monster
1.5 mol/more, promoting the adsorption of metal ions selected from Groups B and Groups of the Periodic Table of the Elements, with no bare spots in the adhesive metal layer formed on the surface or on selected parts of the surface. exposing the surface to an acidic halide solution containing an acidic halide in an amount sufficient to avoid the formation of a metal sheet on the surface; connecting the connector region to a cathode of a power source, contacting the surface with a solution for electroplating a second metal, and contacting an anode of the power source with the solution;
and a method of metallizing a ceramic substrate surface, comprising electroplating a second metal on the surface to form a complete layer of the second metal on the surface or selected portions of the surface. .