DD222346A1 - SOLUTION FOR THE AUTOCATALTIC DIVISION OF PALLADIUM - Google Patents

Abstract

The invention relates to an aqueous solution, which is known to contain palladium in the form of a complex compound, a reducing agent and a stabilizer, for the autocatalytic deposition of palladium layers on metallic and non-metallic materials. By adding a nitrosonaphthol, such as 1-nitroso-2-naphthol, in an amount of 0.1 to 10 g / l, glossy, pore and crack-free palladium layers are achieved. The solution does not tend to spontaneous Palladiumausfaellung and is particularly suitable for applying functional layers on components of electrical engineering / electronics.

Description

Solution for the autocatalytic deposition of palladium

field of use

The invention relates to an aqueous solution containing palladium in the form of a complex compound, a reducing agent and a stabilizer, for the autocatalytic deposition of palladium layers on metallic and non-metallic materials. >

Characteristic of the known technical solutions

There is a variety of aqueous solutions for autocatalytic deposition of palladium known.

The known solutions and processes for the deposition of palladium work with palladium compounds using sodium acetate, citrate, pyrophosphate, nitrite, ammonia, ethylenediamine, thiourea or ethylenediaminetetraacetate as a complexing agent.

Hydrazine hydrate, sodium hypophosphite or sodium borohydride are preferably used as the reducing agent. In addition, these solutions contain additives that are to have an accelerating or stabilizing effect, for example ammonium fluoride. (DE-OS 2341585, US-PS 3,418,143; SU-UHS 395,437; SU-UHS 291,991).

These solutions have the disadvantage that they are not sufficiently stable. After only a short time, spontaneous decomposition occurs at the required working temperatures, so that the solutions become unusable and must be replaced.

The ever increasing demands on the necessary durability of such solutions as well as on their regenerability are not adequately fulfilled by the known solutions.

The unusable solutions must be worked up to recover the palladium content and replaced by fresh solutions, which constantly requires a lot of effort.

Another disadvantage of the previously known solutions is that they can be used only in a very limited temperature range and the addition of reducing agents must be done only in small doses, so that the self-decomposition of the solutions is not triggered prematurely.

Another shortcoming of the 'known solutions' for the deposition of palladium is the tendency for cementation due to charge exchange in connection with less noble metallic base materials, whereby porous and poorly adhering lateadium layers are deposited. Another disadvantage is that layers are deposited which often contain so much hydrogen that they crack due to the internal stresses occurring by hydrogen diffusion. The ef fekt expected by the autocatalytic palladium deposition to equip the workpiece surface with the properties of the precious metal palladium is thereby not achieved or reversed. Such, poorly coated parts are useless for the intended use in electrical engineering / electronics and represent production and material losses.

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.: Object of the invention

The invention aims at the development of a solution for

autocatalytic deposition of palladium, which does not tend to • self-decomposition and which ensures the formation of dense, adherent, .. solid layers. , ,

Essence of the invention

The object of the invention is to achieve an improvement in the service properties of both the solution and the deposited palladium layers by changing the composition of the solutions known for autocatalytic palladium deposition.

It has been found that an aqueous solution which serves for the autocatalytic deposition of palladium layers and contains the palladium ions, a complexing agent, a reducing agent and a stabilizer achieves a long service life and high quality of the deposited palladium layer by addition of a nitroso-naphthol. As Mitrosonaphthol is preferably l-nitroso-2-naphthol, the addition of which takes place in an amount of 0.1 to 10 g / l. The reducing agent used is in particular sodium hypophosphite.

Aysis example '

The invention will be explained in more detail in exemplary embodiments.

Example 1: '<. , · \

Copper samples of the size 10 χ 20 χ 0.3 mm were degreased and dekapiert in a conventional manner in electroplating and then in a coating solution the following composition, palladium-doped:

Palladium (II) choride 1.0 g hydrochloric acid 37%

l-nitroso-2-naphthol. ';

ethylenediamine

sodium

v / asser 10.0 mg surfactant (nonylphenol)

pH 9-12

Temperature 94 + _ 2 C. ·

0.5 0 9 1.0 0 9 1.0 9 15 G 10 , 9 200 9 10.0 mg

Example 2:

As in Example 1 pretreated copper samples were coated in the following solution:

0.75 g of palladium (III) tetaminamine with rat

.5 l »0 g l-nitroso-2-naphthol

, 100 g of ethanolamine

1.0 g sodium hypophosphite. ,

100 g of 'water'

, , 3.0 mg surfactant (nonylphenol) \

, - pH vVert 9-12. , . ' .

Temperature 94 + _ 2 C.

Example 3:>.

Copper samples pretreated as in Example 1 were coated in the following solution:

1.35 g of palladium diamine dinitrite '.'

l-nitroso-2-naphthol

ethylenediamine

ethanolamine

Sodium hypophosphite 100. g of water

Surfactant (nonylphenol) ι

pH 9-12 - ^M -.

Temperature 80 - 95 ^° C * '"

In all the solutions of the examples given, the samples were covered after 2 to 5 minutes with a bright, shiny palladium layer. After 60 minutes, a layer had separated which contains no cracks and pores. The solutions showed no signs of degradation after this coating time.

1.35 G 1.0 9 5.0 G 100 G 5.0 G 100. G 5.0 mg

The specimens were bent through 180 ° over a mandrel of 1 mm 0 , whereby the palladium layer at the bending surfaces still remained firmly connected to the substrate. The coating experiments were repeated after 24 hours with the same result.

The coating solution had been held at 95 + 2 ⁰ C during this time.

Claims (3)

Invention claim: A solution for autocatalytic palladium deposition which contains a palladium compound, a reducing agent, complexing agent and stabilizers, characterized in that a solution of nitrosonaphthol is additionally added to this solution. : 2. Solution according to item 1, characterized in that is used as an additive l-nitroso-2-naphthol .. 3. Solution according to item 1, characterized in that the addition was carried out in an amount of 0.1 to 10 g / 1