JP3105502B1 - Noble metal sol and method for producing the same - Google Patents

Abstract

Kind Code: A1 Similar to known colloidal systems based on palladium, but without the need to simultaneously metallize the jig frame material and to sprout and metallize the non-conductive substrate without replacement. PROBLEM TO BE SOLVED: To provide a colloid system having a precious metal which can be inexpensive. A fine-grained precious metal bud for pretreating a non-conductive substrate before subsequent metallization without external current or metallization by electroplating. Colloidal methanesulfone acidic noble metal sol for installing crystals

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to the pretreatment of non-conductive surfaces made from noble metal-methanesulphonate, methanesulphonic acid and tin (II) methanesulphonate in water for subsequent electroplating. A new colloidal system for

[0002]

BACKGROUND OF THE INVENTION In order to initiate metal deposition in metallizing baths, non-conductive surfaces made of plastic or ceramic impede the metastable equilibrium of the reducing bath due to metal deposition without external current, There must be a metal germ on the surface of the metal germ that initiates metal deposition, or there must be so much metal germ that metallization by direct electroplating can be performed.

[0003] Such metal germs can be installed by immersion in a suitable activator solution, as is known.
Known activating metals include palladium, silver and gold. Ionogenic and colloidal systems for activating such non-conductive surfaces have been known since 20 years, for example Kunststoff-Metallisierung, Handbuch fuer Teorie
See und Praxis, Leuze Verlag, Saulgau or DE 1197720.

In the case of an ionogen system, it is immersed in a tin (II) salt solution, for example, a tin (II) chloride solution for activation. Upon rinsing in water, a gel consisting of tin oxide hydrate adheres to the surface. Subsequently, when immersed in a noble metal salt, for example, a silver nitrate (I) solution or a palladium (II) chloride solution, tin (II) contained in the gel layer is partially oxidized to tin (IV). The ions are reduced to noble metal buds and embedded in the gel layer. This ionogen system causes bud formation on the entire surface,
This means that the article holder is also covered, so that the activated substrate can be replaced with a non-activated article holder before the subsequent chemical metallization to avoid metallization of the article holder or to periodically replace the article holder. Must be demetalized.

[0005] The replacement or regular demetallization of article holders is very costly, so that palladium colloids are mixed in a colloidal system which can act selectively,
As a result, a sufficient germination of the article to be metallized is possible without the metallization of the jig frame material. Such solutions are prepared by reacting palladium (II) chloride with tin (II) chloride in a hydrochloric acid solution. Again, in the redox reaction, palladium (II) is reduced to metallic palladium, while tin (II) is oxidized to tin (I
V). The palladium buds are surrounded by the tin oxide hydrate gel formed in this case and are kept colloidal in solution. The solution thus produced is dark and opaque due to metal germs formed in the redox reaction. The metal blasts required for chemical metal deposition are:
It is already contained in the colloidal activation solution. When the substrate is immersed in this colloidal solution, a sufficient amount of the encapsulated palladium germ-containing gel particles is adsorbed onto the article surface, but not to the same extent on the jig frame material. Upon subsequent washing in an alkaline or acidic solution, the tin oxide hydrate partially dissolves, exposing palladium blasts.

[0006] Since no inexpensive precious metal-based colloid systems have been known so far, palladium is by far the most important metal in industry for the budding of non-conductive surfaces.

[0007]

It is therefore an industrial object of the present invention to provide a non-conductive substrate in a manner similar to the known colloidal systems based on palladium, but without simultaneously metallizing the jig frame material. The aim was to find a colloidal system with inexpensive precious metals that could sprout and metallize without replacement.

[0008]

The noble metal methanesulfonate, in particular silver (I) methanesulfonate, is reacted with tin (II) methanesulfonate in a methanesulfonic acid solution to form a colloidal solution having silver metal blasts. And the above-mentioned problem was solved. As in the case of the palladium chloride / tin chloride system, in this case too, the redox reaction reduces the noble metal ions to metal and conversely tin (I
I) is oxidized to tin (IV).

Accordingly, a first embodiment of the present invention provides a fine-grained noble metal germ for pretreating a non-conductive substrate without subsequent external current or prior to metallization by electroplating. Is a colloidal noble metal methanesulfonate sol.

Suitable noble metals from which such colloidal systems can be prepared, in particular silver-salt solutions and tin (II)-
Searching for salt solutions is difficult.

Most industrially available noble metal salts, especially silver salts, are, for example, silver chloride or silver sulphate, which have a relatively poor solubility or which are provided industrially as, for example, silver nitrate or silver cyanide. Incompatible with possible acid tin (II) salt solutions. For example, tin (II) ions are harmfully oxidized by nitration in colloid formation, while alkaline silver cyanide solutions react with acidic tin (II) salt solutions with the formation of toxic hydrocyanic acid vapors. However, well-soluble and possibly mutually compatible fluoride-containing noble metal salts, in particular silver and tin salts, such as fluoride, silicofluoride or borofluoride, are, for toxicological reasons, relatively susceptible to their relatively high corrosivity. And its drainage handling problems are not particularly suitable for the purposes of the present invention.

In a surprisingly advantageous way, the problem is:
The problem could be solved by using the noble metal methanesulfonate instead of the normal metal chloride and using methanesulfonate instead of the normal hydrochloric acid solution.

This combination according to the invention shows that most noble metal methanesulfonic acids such as silver (I) methanesulphonate and tin (II) methanesulphonate are relatively easily soluble in solutions of methanesulphonic acid, It has the advantage that it can be mixed with one another over a wide concentration range. Methanesulfonic acid for the production of metal salts and activation solutions is available today in industrially sufficient quantities. Handling and disposal are comparable to the hydrochloric acid systems with palladium colloids used today. The corrosivity of the methanesulfonic acid system is advantageously significantly less than that of the hydrochloric acid system. The treatment of the resulting wastewater is simple and can be carried out without special investment. Most additives and buffers known per se, such as are used today for the optimization of the hydrochloric form with partially palladium colloids, can also be applied in the colloidal systems according to the invention based on methanesulfonic acid.

Similar to hydrochloric acid systems with palladium colloids, short and long term stable methanesulfonic acid precious metal colloid systems can be prepared. A system that is stable for several months has the advantage that it is particularly suitable for long-term use, for example in the production of printed wiring boards. Solutions that are stable for only a few hours or days may require liquids and expensive noble metals in the case of discontinuous working methods, e.g., in the case of metallizing relatively large parts and small-volume products after the deposition of noble metal particles. Has the advantage that it can be easily separated and can be disposed of or recycled accordingly.

This means that the metallizing of ordinary non-conductive substrates is possible using the colloidal system of methanesulfonic acid according to the invention, for example, using inexpensive silver. The quality of the metallization is in all respects consistent with the prior art achieved today with palladium colloidal sols which are hydrochloric.

The methanesulfonic acid system described is in this case clearly less corrosive to equipment and substrates, for example in the production of printed wiring boards. When preparing the precious metal colloidal system of silver-based methanesulfonic acid as described above, this colloidal system is significantly less expensive than the now common hydrochloric acid palladium colloidal system.

[0017]

EXAMPLES Examples of Colloids: Example 1: Approximately 800 demineralized water in a one liter volumetric flask.
ml, 17 g of 70% by weight of methanesulfonic acid, 26 g of a 51% by weight solution of tin (II) methanesulfonate and 38%
5 g of a mass% silver methanesulfonate solution was poured in and replenished to 1 liter with demineralized water.

After about 8 hours at room temperature, the initially clear, colorless solution became dark brown and opaque. The colloid system itself was homogeneous and was stable for more than one year at the time of filing.

Example 2 800 ml of demineralized water was charged into a 1 liter volumetric flask, and 5.7 g (70% by weight) of methanesulfonic acid and tin methanesulfonate (I
I) The solution was mixed with 20.8 g (51% by mass) of the solution and 5 g (38% by mass) of the silver (I) methanesulfonate solution, and replenished with demineralized water to 1 liter. The solution turned dark after about 20 minutes and after several hours it actually turned black. In a thin layer, the solution was clear and dark brown.

Dilution example: Dilutions (1/2, 1/4 and 1/8) were additionally produced in a part of this solution using demineralized water. This solution was stored at room temperature and observed. After one month, the dilutions 1/4 and 1/8 had decomposed with the precipitation of a bottom precipitate. The starting solution and dilution 1/2 were still stable after 2 months.

Metallizing Example: The problem of metallizing non-conductive materials using electroplating coatings arises in this technology mainly in two applications.
One is copper plating (printed wiring board technology) of a layered press material made of glass fiber reinforced epoxy resin, and the other is electroplating of a processed product made of graft-polymerized ABS-plastic. Glass, ceramic and a number of different plastic materials, such as polycarbonate, tetrafluoroethylene or polyethylene terephthalate, are generally metallized by other methods, for example, high vacuum deposition, but the technique of coating these materials by electroplating has been developed. It is becoming important because in this case there is a cost advantage.

In order to investigate the suitability of the silver sol for metallizing non-conductors produced as described above, a glass target support for microscopy and a printed wiring board (glass-reinforced EP-resin) Strands made of base material, ABS-plastic and PVC-plastisol coated copper strips were produced as models for insulated electroplated jig frames.

All samples were subjected to the same treatment:-pre-wash in a commercial cleaner (Mucasol® ⁾ -rinse in demineralized water-only ABS plastic for 5 minutes at room temperature with chromic sulfuric acid
Immersion in ¹ and rubberization of jig frame-Only epoxy resin is immersed in 96 wt% sulfuric acid at room temperature for 5 minutes, rubberization of jigframe-Rinse-1 minute, 2 minutes, 4 minutes and 8 minutes at room temperature Example 2 Activation / germination with colloid according to ^2- Rinse-Immersion in 1 molar oxalic acid for 1 min at room temperature-Rinse-Copper plating without current ³ (plastic sample 5 min,
15 minutes glass sample) - rinsing - rinsing with pure alcohol (ethanol) - Drying _{^{1 CrO 3 75g / l, H}} 2 SO 4 250g / l,
The starting solution was passed remaining water ² days and diluted ^{3 FA Lowenheim, Modern Electroplating, 3.} Ed 19
74, p .: 736, Formulated by Preparation 3 from John Wiley & Sons, New York : All samples were metallized after processing, except for the jig frame insulation.

The glass object support had the lowest density of silver germs on the surface, which required about 15 minutes to form a closed copper layer.

The plastic samples showed a homogeneous matte surface after the described corrosion treatment. The germination density at the time of germination formation using silver sol of methanesulfonic acid is high,
Each sample strand was completely metallized for 5 minutes.

The jig frame insulator was treated in exactly the same manner as the plastic sample. The surface sprouted, followed by a cloudy, disorganized copper deposit in an autocatalytic copper bath. However, this deposit was not further enhanced in the subsequent current-carrying process. In the next run of the electroplating cycle, the thin copper plating layer was successfully removed during the next charge etch.

The problem of non-conductor metallization is the production of a metal layer on the surface of the non-conductor, which allows the metallized part to be treated like a metallic part. Characteristic of the metallic state is high reflection of visible light and conductivity. This is achieved by processing.

In addition to the metallic state of the deposited layer, this layer must adhere firmly on the non-conductive surface. In the glass object support for testing, set up an adhesive film into strands (Tesa ^(R)), and then peeled off rapidly from the surface. The film was peeled from the surface without copper particles.

In the case of a sample consisting of ABS and EP, additionally placed a grid cut, bonding the adhesive film thereon ^{(Tesa (R)),} and then rapidly peeled off (DIN 53 151). The copper particles were not stripped.

The test results showed that the copper layer provided according to the invention was better than the adhesive strength on copper of a commercially available adhesive film (Tesa® ⁾ . This result is consistent with the prior art using commercially available palladium hydrochloride colloid systems.

──────────────────────────────────────────────────続 き Continued on the front page (72) Inventor Peter Kunz Germany Feichlingen in der Breite 22 (58) Fields studied (Int. Cl. ⁷ , DB name) C23C 18/00-18/54 C25C 1 / 20 C25D 5/54

Claims (6)

(57) [Claims] 1. A colloidal noble metal methanesulfone for setting up fine-grained noble metal germs for pretreating a non-conductive substrate prior to subsequent metallization without external current or metallization by electroplating. Acid salt sol. 2. The colloidal noble metal meta according to claim 1, further comprising a known additive of a hydrochloric palladium sol.
Sulfonic acid sol. 3. The colloidal noble metal methanesulphate according to claim 1, wherein tin oxide hydrate is used as the colloid-forming agent.
Fonate sol. 4. The colloidal noble metal methanesulfonate sol of claim 1, wherein the noble metal is selected from the group consisting of silver, gold, platinum and palladium. 5. The colloid according to claim 1, wherein deionized water, methanesulfonic acid, tin (II) methanesulfonate and noble metal methanesulfonate are used. Production method of noble metal methanesulfonate sol. 6. The process according to claim 5, wherein 1 to 100 g / l of methanesulfonic acid, 0.5 to 50 g / l of tin (II) methanesulfonate and 0.1 to 10 g / l of the noble metal methanesulfonate are used. Method.