CN101550569A - Non-cyanide alkaline copper plating bath, preparation and use method thereof - Google Patents

Abstract

The present invention is a new non-cyanide alkaline copper plating bath, preparation and use method thereof. In the copper plating bath, using copper sulfate or basic copper carbonate as main salt, using hydroxy-ethylidene diphosphonic acid as main complexant, using trisodium citrate, potassium citrate or potassium sodium tartrate as auxiliary complexant, using sodium nitrate or potassium nitrate as conductive salt, using sodium hydroxide or potassium hydrate as pH value regulator; the operation conditions are: cathode current density is 0.5-3.0 A/dm [2], pH of plating bath controlled between 12 and 13, plating bath temperature is 50-70 DEG. Comparing with the prior known technology, the invention has following advantages or positive effects: simple plating bath formula, easy control and operation, wide temperature range of plating bath using, high current efficiency, fine crystallization coating, good appearance color, stable plating bath, strong uniform plating and covering ability, low cost, easy wastewater treatment. The invention can be used for pre copper plating or direct electro-coppering instead of virulent cyaniding electro-coppering process.

Description

A kind of cyanide-free alkaline copper plating solution and preparation thereof and using method

Technical field

The present invention relates to the electroplating technology field, particularly a kind of cyanide-free alkaline copper plating solution and preparation and using method.

Background technology

The crystallization of cyanide electroplating copper layer is careful, bonding force good, all platings of plating bath, leveling property, stability are also very good, can be on iron and steel, zinc and zinc alloy matrix part Direct Electroplating.But contain cyanide ion in the cyanide electroplating copper liquid, toxicity is big, and waste water and waste liquid are difficult, and contaminate environment is serious, and is detrimental to health.Therefore, people are seeking the cyanide-free copper electroplating technology that can substitute cyanide copper always.Existing cyanide-free copper electroplating technology mainly contains pyrophosphate method of electro-plating copper, vitriol electro-coppering, quadrol electro-coppering, fluoroborate plating copper, citric acid-tartrate electro-coppering, HEDP electro-coppering and thionamic acid electro-coppering system etc.Wherein, pyrophosphate copper plating system large-scale application is handled but generally also need to carry out cyanide pre-plating copper in production, and the plating solution maintenance complexity, and cost is higher.Citric acid-tartrate electro-coppering system also has and is used on a small quantity producing, but bonding force is not ideal enough, and the plating bath cost is also higher, and long-term the placement is easy to mildew.Bonding force extreme difference during vitriol electro-coppering system Direct Electroplating.HEDP electro-coppering system almost can compare favourably with cyanide electroplating, but the sewage disposal expense is still higher.Other several technologies are to rest on the experimental study stage also because of all there being different defectives basically, also are not used for industrial production fully.

Summary of the invention

The objective of the invention is at the prior art above shortcomings, provide a kind of electroplate liquid formulation simple, be easy to non-cyanide alkaline copper plating bath and the preparation and the using method of controlling and operating.

Adopt hydroxy ethylene diphosphonic acid as main complexing agent in the non-cyanide alkaline copper plating bath of the present invention, addition is 120～180g/L.Addition is low excessively, and cathodic polarization reduces, and electroconductibility is relatively poor, and bath voltage is higher, and liberation of hydrogen is serious, and anode dissolution is bad, and coating is coarse, and the light quantity scope is narrower.Addition is too high, and plating solution performance improves not obvious, also can increase cost; The main salt of electro-coppering adopts ventilation breather or copper sulfate.Addition when using ventilation breather is 12～20g/L, and the addition when using copper sulfate is 25～45g/L.Addition is low excessively, and cathodic polarization improves, and specific conductivity descends, and bath voltage is higher, and liberation of hydrogen is serious, and anode dissolution is bad, and coating light quantity scope is narrower.Addition is too high, and cathodic polarization reduces, and crystallization is thick.

Add Citrate trianion (available trisodium citrate, citric acid tri potassium) or tartrate (Seignette salt) in the non-cyanide alkaline copper plating bath of the present invention as auxiliary complex-former, to improve the polarization performance of electrolytic copper plating solution, especially obvious to the cathodic polarization effect that significantly improves plating bath under low current density.Be used and guarantee the normal dissolving of anode copper increasing current density range, enlarging the light quantity scope simultaneously with an amount of conducting salt.The addition of trisodium citrate or citric acid tri potassium is 25～40g/L, and the addition of Seignette salt is 20～40g/L.It is not obvious that addition is crossed low effect, and addition is too high can to reduce cathodic polarization, dwindles coating light quantity scope.

Add an amount of conducting salt in the non-cyanide alkaline copper plating bath of the present invention, as SODIUMNITRATE or saltpetre.The adding of conducting salt can reduce bath voltage, reduces the generation of liberation of hydrogen side reaction.Addition when adding SODIUMNITRATE or saltpetre is between 4～8g/L.If must re-plating after the electro-coppering during nickel, it is following or do not add that the addition of nitrate should be controlled at lower limit.

Add the adjustment agent as electroplate liquid pH value of sodium hydroxide or potassium hydroxide in the non-cyanide alkaline copper plating bath of the present invention, with the potential of hydrogen of stable electrical plating bath, its addition is 20～40g/L.

The compound method of non-cyanide alkaline copper plating bath of the present invention is as follows: 1. with distilled water ventilation breather is modulated into pasty state, or copper sulfate is dissolved to clear solution; 2. with distilled water hydroxy ethylene diphosphonic acid is dissolved, add hydrogen peroxide oxidation reductibility composition wherein, add sodium hydroxide or potassium hydroxide solution again, pH is adjusted between 8.0～9.0; 3. under agitation condition, with solution 1. slowly join solution 2. in, make it fully by complexing; 4. with auxiliary complex-former, conducting salt dissolved in distilled water, and join solution 3. in; 5. with sodium hydroxide or potassium hydroxide bath pH value is adjusted between 12～13 once more; 6. with using behind the distilled water constant volume.

Compared with prior art, the present invention has following advantage and positively effect:

1, electrolytic copper plating solution is the non-cyanide alkali plating bath, and composition is simple, and easy operation and maintenance is applicable to the Direct Electroplating on steel-iron components surface.

2, the electrolytic copper plating solution polarization performance is good, and cathode efficiency is higher, generally all more than 80%.

3, the electrolytic copper plating solution that is added with saltpetre has higher limit cathode current density, the current density range broad in coating light district, and the upper limit of current density can reach 3A/dm ²

4, the covering power of electrolytic copper plating solution is better than citric acid-tartrate electro-coppering and cyanide copper system.After adding Tripotassium Citrate and saltpetre, covering power is more than 86%.

5, binding force of cladding material can be satisfied the demand, and the pre-plating layer that can be used as copper-nickel-chromium protecting decorative coating uses.Bonding force intensity is a little less than the cyaniding system, but is higher than citric acid-tartrate system.

6, the stability of electrolytic copper plating solution is high, works continuously through 200h, and plating bath still can use.

Plating bath use temperature wide ranges of the present invention, the current efficiency height, the coating crystallization is careful, and appearance luster is good, bath stability, all plating and hiding power are strong, and cost is low, and wastewater treatment is easy.Can replace containing the cyanide electroplating process for copper of severe toxicity, use as pre-copper facing or Direct Electroplating copper.

Embodiment

The invention will be further described with embodiment below.

Embodiment 1:

Plating bath is formed:

Hydroxy ethylene diphosphonic acid 120g/L

Ventilation breather 12g/L

Potassium hydroxide 30g/L

Citric acid tri potassium 30g/L

Saltpetre 6g/L

Method for making:

1. with distilled water ventilation breather is modulated into pasty state; 2. with distilled water hydroxy ethylene diphosphonic acid is dissolved, add hydrogen peroxide oxidation reductibility composition wherein, add potassium hydroxide or sodium hydroxide solution again, pH is adjusted between 8.0～9.0; 3. under agitation condition, with solution 1. slowly join solution 2. in, make it fully by complexing; 4. citric acid tri potassium, saltpetre are used dissolved in distilled water respectively, and join successively solution 3. in; 5. with potassium hydroxide or sodium hydroxide bath pH value is adjusted between 12～13 once more; 6. with using behind the distilled water constant volume.

The electrolytic copper plating solution cathode current density is 1.0A/dm during plating ², bath pH value is 13.0, bath temperature is 55 ℃.

Embodiment 2:

Plating bath is formed:

Hydroxy ethylene diphosphonic acid 180g/L

Ventilation breather 20g/L

Potassium hydroxide 40g/L

Seignette salt 35g/L

Saltpetre 4g/L

Method for making:

1. with distilled water ventilation breather is modulated into pasty state; 2. with distilled water hydroxy ethylene diphosphonic acid is dissolved, add hydrogen peroxide oxidation reductibility composition wherein, add sodium hydroxide or potassium hydroxide solution again, pH is adjusted between 8.0～9.0; 3. under agitation condition, with solution 1. slowly join solution 2. in, make it fully by complexing; 4. Seignette salt, saltpetre are used dissolved in distilled water respectively, and join successively solution 3. in; 5. with sodium hydroxide or potassium hydroxide bath pH value is adjusted between 12～13; 6. with using behind the distilled water constant volume.

The electrolytic copper plating solution cathode current density is 2.0A/dm during plating ², bath pH value is 12.5, bath temperature is 60 ℃.

Embodiment 3:

Hydroxy ethylene diphosphonic acid 150g/L

Copper sulfate 35g/L

Potassium hydroxide 30g/L

Seignette salt 30g/L

Saltpetre 6g/L

Method for making:

1. with distilled water copper sulfate is dissolved to clear solution; 2. with distilled water hydroxy ethylene diphosphonic acid is dissolved, add hydrogen peroxide oxidation reductibility composition wherein, add sodium hydroxide or potassium hydroxide solution again, pH is adjusted between 8.0～9.0; 3. under agitation condition, with solution 1. slowly join solution 2. in, make it fully by complexing; 4. citric acid tri potassium, saltpetre are used dissolved in distilled water respectively, and join successively solution 3. in; 5. with sodium hydroxide or potassium hydroxide bath pH value is adjusted between 12～13 once more; 6. with using behind the distilled water constant volume.

The electrolytic copper plating solution cathode current density is 2.5A/dm during plating ², bath pH value is 12.0, bath temperature is 65 ℃.

The performance of table 1 embodiments of the invention and cyanide copper and citric acid-tartrate electro-coppering relatively

The contrast index	Covering power (%)	Covering power (%)	Maximum current efficient (%)	Leveling property (%)	Sedimentation velocity (μ m/min)
						Cyanide copper	??75	??100	??80	??90	??0.27
Citric acid-tartrate electro-coppering	??73	??100	??93	??36	??0.18
						Embodiment 1	??84	??100	??78	??95	??0.20
Embodiment 2	??82	??92	??94	??96	??0.22
						Embodiment 3	??80	??94	??88	??92	??0.28

Claims (6)

1, a kind of non-cyanide alkaline copper plating bath, it is characterized in that: use hydroxy ethylene diphosphonic acid as main complexing agent, addition is 120～180g/L, with copper sulfate or ventilation breather as main salt, addition during with copper sulfate is 25～45g/L, or the addition during with ventilation breather is 12～20/L.

2, non-cyanide alkaline copper plating bath according to claim 1 is characterized in that: add auxiliary complex-former Citrate trianion 25～40g/L, or tartrate 20～40g/L.

3, non-cyanide alkaline copper plating bath according to claim 1 is characterized in that: add partially conductive salt SODIUMNITRATE or saltpetre, addition is 4～8g/L.

4, non-cyanide alkaline copper plating bath according to claim 1 is characterized in that: add the adjustment agent as electroplate liquid pH value of sodium hydroxide or potassium hydroxide, addition is 20～40g/L.

5, the preparation method of the described non-cyanide alkaline copper plating bath of claim 1 is characterized in that being undertaken by following: 1. with distilled water ventilation breather is modulated into pasty state, or copper sulfate is dissolved to clear solution; 2. with distilled water hydroxy ethylene diphosphonic acid is dissolved, add hydrogen peroxide oxidation reductibility composition wherein, add sodium hydroxide or potassium hydroxide solution again, pH is adjusted to 8.0～9.0; 3. under agitation condition, with solution 1. slowly join solution 2. in, make it fully by complexing; 4. with auxiliary complex-former, conducting salt dissolved in distilled water, join solution 3. in; 5. with sodium hydroxide or potassium hydroxide bath pH value is adjusted to 12～13 once more; 6. with using behind the distilled water constant volume.

6, the described non-cyanide alkaline copper plating bath using method of claim 1, it is characterized in that: the cathode current density of electrolytic copper plating solution is 0.5～3.0A/dm during plating ², bath pH value is 12～13, bath temperature is 50～70 ℃.