SU1694695A1 - Aqueous solution for chemical copper plating - Google Patents

Abstract

The invention relates to chemical coating, in particular, copper, and can be used in the electronics industry to solder metallized dielectrics for the manufacture of elements of gas discharge devices, to produce microchips. The purpose of the invention is to reduce the electrical resistivity of the coating, increase the resistance to oxidation, the deposition rate, adhesion of the coating to nitride ceramics and increase the stability of the solution. The aqueous solution contains: copper sulfate, hydrated, G 8-12; nitriloacetic acid (NTA), G 20-25; nickel chloride (U), D 3-5; sodium hydroxide, G 15-20; Trilon B, D 20-25; sodium diethyldithiocarbonate, mg 3-6, 40% formaldehyde, 23-30 ml; water up to 1 l. The introduction of NTA and nickel chloride allows to maintain the solution for more than 2 months, to obtain a coating deposition rate of 7-8 µm / h; adhesion to the nitride substrate 60-65 kg / cm; the absence of oxidation of the coating for more than 6 months, the specific electrical resistance of the coating 1.7-1.9-108 ohm-m. The appearance of the coating is pink, uniform, shiny, without spots. 2 tab. cl

Description

The invention relates to chemical coating, in particular, copper, and can be used in the electronics industry to solder dielectrics with hard and soft solders, to develop the application of copper coatings to elements of gas discharge devices.

The purpose of the invention is to reduce the electrical resistivity of the coating, increase its resistance to oxidation, the rate of deposition and adhesion of the coating to nitride ceramics, as well as increase the stability of the solution,

o The solution of chemical copper contains:

Copper sulphate (hydrated), g formaldehyde (40%). ml of sodium diethyldithiocarbonate (DMSC Ms 2), mg 36, sodium hydroxide, g Trilon B, g nitriloacetic acid (NTA) g

8-12

23-20

15-20 20-25

20-25

ABOUT

Che N

ON sQ SL

nickel chloride, g3-5

water ldo 1

Before applying a copper coating on rectangular-shaped nitride ceramic samples with an area of 20 ± 0.05 cm2, their surface is degreased in soda solution for 5 minutes at 70-80 ° C, etched in an alkaline solution with HEDP added at 80 ° C for 2 -5 minutes. To create active sites on the surface, the samples are sensitized in an acidified solution of palladium chloride (P) for 30 seconds and activated in an acidified 0.5% solution of palladium chloride (30 seconds) at room temperature. Solutions of SnCl2 and PdCIa are prepared on the basis of a 0.1% surfactant solution to give the surface a better wettability. Each of the listed operations ends with washing the samples in distilled water.

The electrolyte for chemical surface metallization is prepared by introducing metal salts (taken in the form of hch, osch, chd) powders, previously dissolved in hot distilled water, into a solution of complexing agents (trilon B, NTM) in the presence of alkali.

Formaldehyde is injected before starting the process. Recovery mode: pH 12.8-1.0 is provided by the addition of a concentrated solution of potassium hydroxide.

The prepared samples are placed in thermostatic glass cells, where the surface is metallized with continuous stirring of the solution, measuring pH (with an EV-74 ion meter).

Examples of testing the compositions of the solutions are given in Table 1. The temperature of all electrolytes was 25 ° C, the pH of the solutions was kept constant at 12.8-13.0. The thickness of the coating in all cases is constant and is 10 microns.

The properties of the solutions obtained from these coatings are given in table 2.

The adhesion of chemically precipitated metal coatings was monitored with a tear-off device under a tensile load on a laboratory adhesion meter. The deposition rate of the coatings was determined by measuring the thickness of the coating over a specific time period. The resistivity was calculated by the formula:

R - resistance (measured), I is the length of the sample;

S is the cross-sectional area. The specific volume electrical resistance of the coating was 9.9-14.2-108 Ω-m for the inventive solution 1.7-1.9 109 Ω-m for a known solution. The resulting precipitate of pink copper, uniform, shiny, does not oxidize in air for more than 6 minutes.

The solution remains stable for more than 2 months, and the deposition rate of the coating is 7-8 µm / h.

Claims (1)

Invention Formula An aqueous solution for chemical copper containing copper sulfate, formaldehyde, sodium diethyldithiocarbonate, sodium hydroxide, Trilon B, and an additional complexing agent, characterized in that, in order to reduce the electrical resistivity of the coating, increase its resistance to oxidation, deposition rate, and adhesion of the coating , to nitride kerosene, as well as to increase the stability of the solution, it additionally contains nickel chloride, and as an additional complexing agent, nitriloacetic acid with the following elations components: copper sulphate (pivodny) g8-12 formaldehyde (40%) ml23-30 diethyldithiocarbamate sodium mg3-6. sodium hydroxide, g20-25 Trilon B, G20-25 nitriloacetic acid, g20-25 nickel chloride, g3-5 water, ldo 1. Table 1 Properties of the solution and coating The compositions of the solutions Table 2