CN107190288B - Preparation method of HEDP copper-plated pore-free thin layer - Google Patents

Abstract

The invention belongs to the technical field of cyanide-free copper electroplating processes, and particularly relates to a preparation method of an HEDP copper-plated pore-free thin layer. FirstPolishing with sand paper to remove floating rust, then chemically degreasing and activating, and finally cleaning with deionized water; preparing electroplating solution; electroplating: removing oxide film on copper plate surface by using electrolytic copper plate as anode, activating with 10% -20% diluted hydrochloric acid solution for 5-10 s, placing the treated substrate as cathode in electroplating solution at 50-65deg.C, pH value of 9-11, DC electroplating with current density of 0.5-3.5A/dm ² Electroplating under the cathode moving condition, wherein the moving speed is 3 cm/s-5 cm/s, and obtaining the HEDP copper plating pore-free thin layer. The HEDP alkaline plating solution has low toxicity, environmental protection, little corrosion to production equipment, leveling capability, dispersion capability and deep plating capability reaching or exceeding cyanide copper plating, cathode current efficiency reaching more than 95 percent, and stable plating solution performance.

Description

Preparation method of HEDP copper-plated pore-free thin layer

Technical Field

The invention belongs to the technical field of cyanide-free copper electroplating processes, and particularly relates to a preparation method of an HEDP copper-plated pore-free thin layer.

Background

Cyanide copper plating is the most widely applied and mature preplating technology due to good dispersion capability of plating solution, fine crystallization, good binding force between a plating layer and a matrix, and the like, but toxic and harmful cyanide is used, HCN generated by cyanide carbonation is extremely toxic, the safety requirement on an operating system is strict, and the three-waste treatment cost is high. Development of an environment-friendly cyanide-free copper plating process instead of a cyanide copper plating process is currently the focus of research in the field of electroplating industry.

Although there are a number of cyanide-free copper plating processes, such as sulfate copper plating, ethylenediamine copper plating, pyrophosphate copper plating, and the like; however, each plating solution system has the defects in practical application: such as sulfate copper plating, cannot be directly plated on steel substrates; after ethylenediamine copper plating, nickel is plated, and the binding force is poor; pyrophosphates in the pyrophosphate copper plating are partially hydrolyzed into orthophosphates, and accumulation of orthophosphates can cause cracking of plating solution performance; in addition, the plating layer in the copper plating process needs at least 18 mu m to ensure lower porosity; current cyanide-free copper plating processes are not yet being substantially replaced by cyanide copper plating processes due to these limitations.

The complexing capacity of HEDP and copper ions is close to cyanide, and the HEDP can form different forms of relatively stable complexes with various metal ions such as iron, zinc, copper and the like in a relatively wide pH range, and meanwhile, rust and pollutants on the surface of the HEDP can be removed, so that a compact copper layer with good binding force can be directly obtained without preplating, and the HEDP becomes one of cyanide-free copper plating complexing agents with the highest potential, and has excellent application prospect.

The copper plating layer is a cathodic protection plating layer, is usually used as a bottom layer of a gold, silver, nickel and other plating layers, and for steel-based parts, if HEDP copper plating has a plurality of pores of a pore-free thin layer, a large number of corrosion primary batteries with small anodes and large cathodes can be formed, and the corrosion of steel base materials can not be protected under the corrosion environment, but the corrosion of steel materials can be accelerated; at present, the thickness of the HEDP copper plating void-free thin layer in the carburization and nitridation process of the steel-based part is generally 30-60 mu m, even thicker, copper nodules with larger size and larger number are formed on the surface of the thickened plating layer, and the HEDP copper plating void-free thin layer with poor compactness and poor surface state is difficult to play a good anti-carburization and anti-seepage effect, and further causes resource waste and energy loss to a great extent; the low porosity and good compactness of the copper plating layer are key points for preventing diffusion and permeation of carbon and nitrogen. In order to prepare the high-quality HEDP copper-plated non-porous thin layer with good compactness, students adopt pulse current electroplating after copper pre-soaking, and adopt the process methods of alternating direct current and alternating current electroplating on a matrix to obtain the HEDP copper-plated non-porous thin layer with low porosity of about 20 mu m, but the deposition speed is slower, the operation process is complex, and the equipment requirement is higher, so that the popularization and the application are difficult.

Disclosure of Invention

Aiming at the defects of the prior art, the invention provides a preparation method of an HEDP copper plating void-free thin layer, which has simple operation process, plating solution leveling capability, dispersion capability and deep plating capability reaching or exceeding cyanide copper plating, good plating binding force, excellent compactness, no voids with the thickness of only 6-8 mu m and can completely meet the industrial requirements of electroplated copper.

The invention adopts the technical scheme that:

a preparation method of an HEDP copper-plated pore-free thin layer comprises the following steps:

1) And (3) substrate processing: firstly polishing with sand paper to remove floating rust, then chemically degreasing, and finally cleaning with deionized water;

the chemical degreasing liquid comprises the following components: 60g/L to 80g/L of sodium hydroxide, 30g/L to 50g/L of sodium carbonate, 30g/L to 50g/L of trisodium phosphate, 10g/L to 30g/L of sodium silicate, and the temperature is 75 ℃ to 95 ℃ and the time is removed; then flowing warm water for washing, flowing cold water for washing, deionized water for washing, and then activating, wherein the components of the activating solution are as follows: hydrochloric acid 20 g/L-35 g/L, room temperature, time 1 min-2 min; then flowing cold water for washing, deionized water for washing, and neutralizing, wherein the neutralizing liquid comprises the following components: 30g/L to 50g/L of sodium carbonate, and 0.5min to 2min at room temperature;

2) Preparing an electroplating solution: the electroplating solution comprises basic copper carbonate, potassium sodium tartrate and wetting agent, wherein the basic copper carbonate is prepared into paste by deionized water, the other components are respectively dissolved by deionized water for standby, and a proper amount of 50g/L KOH solution is prepared for standby;

adding 60wt.% HEDP aqueous solution into a plating tank, and adding half of the total hydrogen peroxide under the condition of slow stirring; adding the alkali copper carbonate, the aqueous solution of potassium carbonate, the aqueous solution of sodium potassium tartrate and the aqueous solution of wetting agent which are prepared into paste under the condition of continuously stirring; adding the rest hydrogen peroxide and deionized water, and adjusting the pH value to the process range;

wherein, the electroplating solution comprises the following components:

12-16 g/L of basic copper carbonate;

5-16 g/L of potassium sodium tartrate;

30-50 g/L of potassium carbonate;

60wt.% HEDP aqueous solution 100-135 ml/L;

30% wt. hydrogen peroxide aqueous solution 2-3 ml/L;

the wetting agent is 0.2-0.8 g/L polyethylene glycol 6000 or 0.2-1.0 g/L sodium dodecyl sulfonate;

3) Electroplating: taking an electrolytic copper plate as an anode, removing an oxide film on the surface of the copper plate, activating the substrate treated in the step 1) by a 10% -20% dilute hydrochloric acid solution for 5-10 s, placing the substrate as a cathode in the electroplating solution in the step 2), wherein the temperature is 50-65 ℃, the pH value is 9-11, and the current density is 0.5-3.5A/dm ² Electroplating under the cathode moving condition, wherein the moving speed is 3 cm/s-5 cm/s, and obtaining the HEDP copper plating pore-free thin layer.

The invention has the beneficial effects that: compared with the prior art, the invention has the outstanding advantages that: the HEDP alkaline plating solution has low toxicity and environmental protection, has little corrosion to production equipment, has leveling capability, dispersion capability and deep plating capability reaching or exceeding cyanide copper plating, has cathode current efficiency of more than 95 percent, has stable plating solution, can still be normally used after being continuously electrified for 200A & h, and has convenient bath solution maintenance; the plating layer is fine in crystallization, is thickened to 100 mu m and basically has no copper nubbin, has good binding force and excellent compactness, has no pore only 6-8 mu m in thickness, can be particularly used as a compact protective layer of steel-based parts, reduces the thickness of a thin pore-free copper plating layer in a carburizing and nitriding process HEDP, saves energy resources, and is an environment-friendly copper plating process capable of replacing cyanide copper plating, so that good economic and social benefits are generated.

Detailed Description

The following describes the embodiments of the present invention in further detail with reference to the drawings.

Example 1

1) And (3) substrate processing: sequentially polishing with No. 600, no. 800 and No. 1000 abrasive paper to remove surface rust; then chemical degreasing is carried out, and the chemical degreasing liquid comprises the following components: 70g/L of sodium hydroxide, 40g/L of sodium carbonate, 40g/L of trisodium phosphate, 20g/L of sodium silicate, and the temperature is 80 ℃ for 20min; then flowing warm water for washing, flowing cold water for washing, deionized water for washing, and then activating, wherein the components of the activating solution are as follows: 25g/L hydrochloric acid, room temperature and time of 90s; then flowing cold water for washing, deionized water for washing, and neutralizing, wherein the neutralizing liquid comprises the following components: 35g/L sodium carbonate, room temperature and 60s; then flowing cold water for washing and deionized water for washing;

2) Preparing an electroplating solution: 1L HEDP copper plating solution is prepared, and the components are as follows:

15g/L of basic copper carbonate;

14g/L of potassium sodium tartrate;

40g/L of potassium carbonate;

HEDP (60% aqueous solution) 110ml/L;

hydrogen peroxide (30% aqueous solution) 2ml/L;

polyethylene glycol (6000) 0.4g/L.

3) Electroplating: taking an electrolytic copper plate as an anode, performing activation treatment for 10 seconds by using a 10% dilute hydrochloric acid solution to remove an oxide film on the surface of the copper plate, taking the substrate treated in the step 1) as a cathode, placing the substrate in the electroplating solution in the step 2), and performing direct current electroplating at 55 ℃ and pH value of 9.6Density of 1A/dm ² Electroplating under the cathode moving condition, wherein the moving speed is 3cm/s, and obtaining the HEDP copper plating pore-free thin layer.

Example 2

1) And (3) substrate processing: sequentially polishing with No. 600, no. 800 and No. 1000 abrasive paper to remove surface rust; then chemical degreasing is carried out, and the chemical degreasing liquid comprises the following components: 70g/L of sodium hydroxide, 40g/L of sodium carbonate, 40g/L of trisodium phosphate, 20g/L of sodium silicate, and the temperature is 80 ℃ for 20min; then flowing warm water for washing, flowing cold water for washing, deionized water for washing, and then activating, wherein the components of the activating solution are as follows: 25g/L hydrochloric acid, room temperature and time of 90s; then flowing cold water for washing, deionized water for washing, and neutralizing, wherein the neutralizing liquid comprises the following components: 35g/L sodium carbonate, room temperature and 60s; then flowing cold water for washing and deionized water for washing;

2) Preparing an electroplating solution: 1L HEDP copper plating solution is prepared, and the components are as follows:

15g/L of basic copper carbonate;

14g/L of potassium sodium tartrate;

40g/L of potassium carbonate;

HEDP (60% aqueous solution) 110ml/L;

hydrogen peroxide (30% aqueous solution) 2ml/L;

sodium dodecyl sulfonate 0.4g/L.

3) Electroplating: taking an electrolytic copper plate as an anode, performing activation treatment for 10 seconds by using a 10% dilute hydrochloric acid solution to remove an oxide film on the surface of the copper plate, taking the substrate treated in the step 1) as a cathode, placing the substrate in the electroplating solution in the step 2), and performing direct current electroplating at 55 ℃ and pH value of 9.6 with current density of 1A/dm ² Electroplating under the cathode moving condition, wherein the moving speed is 3cm/s, and obtaining the HEDP copper plating pore-free thin layer.

Performing a cross-cut test, a bending test and a thermal shock test according to GB/T5270-2005 on the HEDP copper-plated non-porous thin layer obtained by the two examples to detect the adhesion strength of the HEDP copper-plated non-porous thin layer and a base material, wherein a plating layer in a square lattice of 1mm is not peeled off in the cross-cut test; continuously bending until the base metal breaks and the coating is still undamaged; after the thermal shock test is carried out for 1 hour at the constant temperature of 300 ℃, the coating is immersed into normal-temperature water rapidly and has no bubbling, peeling and falling off; the HEDPHEDP copper plating non-porous thin layer has good bonding force with the base material. The porosity of the coating is detected by a filter paper pasting method and an immersion method according to GB/T17720-1999, and the porosity of the HEDP copper plating non-porous thin layer with the thickness of 6-8 mu m can be reduced to 0, which shows that the coating has fine crystallization and excellent compactness. The dispersion capacity of the plating solution is detected by adopting a far-near cathode method, the dispersion capacity is up to 81.8%, the leveling capacity of the plating solution is detected by adopting a roughness method, the leveling capacity is up to 77.4%, the deep plating capacity of the plating solution is detected by adopting a blind hole method, the deep plating capacity is up to 100%, the cathode current efficiency is detected by adopting a copper coulometer, and the cathode current efficiency is up to 96.3% for steel pipe fittings with the outer diameter of 10mm, the inner diameter of 7mm and the pipe length of 150 mm. Therefore, the HEDP plating solution has excellent performance, the obtained plating layer has extremely low porosity and good compactness, and can be used as a protective layer and an anti-carburization and anti-nitriding barrier layer of steel-based parts.

Claims (1)

1. The preparation method of the HEDP copper-plated pore-free thin layer is characterized by comprising the following steps of:

1) And (3) substrate processing: firstly polishing with sand paper to remove floating rust, then chemically degreasing and activating, and finally cleaning with deionized water;

2) Preparing an electroplating solution: preparing electroplating solution according to the following components and contents;

wherein, the electroplating solution comprises the following components in percentage by weight:

the wetting agent is 0.2-0.8 g/L polyethylene glycol 6000 or 0.2-1.0 g/L sodium dodecyl sulfonate;

3) Electroplating: taking an electrolytic copper plate as an anode, removing an oxide film on the surface of the copper plate, activating the substrate treated in the step 1) by a 10% -20% dilute hydrochloric acid solution for 5-10 s, placing the substrate as a cathode in the electroplating solution in the step 2), wherein the temperature is 50-65 ℃, the pH value is 9-11, and the current density is 0.5-3.5A/dm ² Electroplating under the cathode moving condition, wherein the moving speed is 3 cm/s-5 cm/s, and obtaining the HEDP copper plating pore-free thin layer.