阅读说明：本技术 一种无氰镀铜打底的方法 (Cyanide-free copper plating bottoming method ) 是由 黄恩礼 梁锦荣 洪文彦 洪大照 于 2021-07-15 设计创作，主要内容包括：本发明公开了一种无氰镀铜打底的方法,该方法包括以下步骤：将镁合金前处理、预浸、预镀无氰铜和无氰镀铜；所述预镀无氰铜,镀液包括以下制备原料：铜盐Ⅰ、有机膦酸盐Ⅰ、多烯多胺类化合物Ⅰ、碳酸盐Ⅰ、硫基杂化化合物Ⅰ和环烷基磺酸盐Ⅰ；所述无氰镀铜,镀液包括以下制备原料：铜盐Ⅱ、有机膦酸盐Ⅱ、多烯多胺类化合物Ⅱ、碳酸盐Ⅱ、硫基杂化化合物Ⅱ、环烷基磺酸盐Ⅱ和不饱和烃氧基醚。本发明在镁锂合金材料上获得覆盖均匀、结合力优良的镀层,满足了高结合力要求,同时工艺流程简单稳定,提高了工业化生产的良品率。(The invention discloses a cyanide-free copper plating priming method, which comprises the following steps: pretreating, pre-soaking and pre-plating a magnesium alloy with cyanide-free copper and cyanide-free copper plating; the pre-plating non-cyanide copper plating solution comprises the following preparation raw materials: copper salt I, organic phosphonate I, polyene polyamine compound I, carbonate I, sulfenyl hybrid compound I and cycloalkyl sulfonate I; the cyanide-free copper plating solution comprises the following preparation raw materials: copper salt II, organic phosphonate II, polyene polyamine compound II, carbonate II, sulfenyl hybrid compound II, cycloalkyl sulfonate II and unsaturated alkoxy ether. The invention obtains the plating layer with even coverage and excellent binding force on the magnesium-lithium alloy material, meets the requirement of high binding force, has simple and stable process flow and improves the yield of industrial production.)

1. A cyanide-free copper plating bottoming method is characterized by comprising the following steps: the method comprises the following steps:

pretreating, pre-soaking and pre-plating a magnesium alloy with cyanide-free copper and cyanide-free copper plating;

the pre-plating non-cyanide copper plating solution comprises the following preparation raw materials:

copper salt I, organic phosphonate I, polyene polyamine compound I, carbonate I, sulfenyl hybrid compound I and cycloalkyl sulfonate I;

the cyanide-free copper plating solution comprises the following preparation raw materials:

copper salt II, organic phosphonate II, polyene polyamine compound II, carbonate II, sulfenyl hybrid compound II, cycloalkyl sulfonate II and unsaturated alkoxy ether.

2. The method for cyanide-free copper plating priming according to claim 1, characterized in that: the pre-dipping solution comprises the following preparation raw materials: organic phosphonate III and polyene polyamine III; preferably, the pre-dipping solution comprises the following raw materials prepared by weight: 1 to 5 percent of organic phosphonate, 5 to 12 percent of polyene polyamine compound and the balance of water.

3. The method for cyanide-free copper plating priming according to claim 1, characterized in that: the preplating process is characterized in that cyanide-free copper is preplated, and the plating solution is composed of the following preparation raw materials in parts by weight:

3 to 6 percent of copper salt I;

15 to 25 percent of organic phosphonate I;

5 to 12 percent of polyene polyamine compound I;

5 to 12 percent of carbonate I;

0.01 to 0.03 percent of sulfur-based hybrid compound I;

0.1 to 0.4 percent of naphthenic base sulfonate I;

and the balance water.

4. The method for cyanide-free copper plating priming according to claim 1, characterized in that: the cyanide-free copper plating solution consists of the following preparation raw materials in parts by weight:

6 to 10 percent of copper salt II;

18 to 28 percent of organic phosphonate II;

4 to 8 percent of polyene polyamine compound II;

5 to 12 percent of carbonate II;

0.02 to 0.05 percent of sulfur-based hybrid compound II;

0.2 to 0.5 percent of naphthenic base sulfonate II;

0.01 to 0.03 percent of unsaturated alkoxy ether;

and the balance water.

5. The method for cyanide-free copper plating priming according to claim 1, characterized in that: the pretreatment comprises the following steps: acid etching, activating and zinc dipping the magnesium alloy.

6. The method for cyanide-free copper plating priming according to claim 5, wherein: the acid etching solution comprises the following preparation raw materials: inorganic acid, organic phosphonic acid compound and nitrate I; preferably, the acid etching solution is prepared from the following raw materials in parts by weight: 0.5 to 2.5 percent of inorganic acid, 0.8 to 3 percent of organic phosphonic acid compound, 0.05 to 0.5 percent of nitrate I and the balance of water.

7. The method for cyanide-free copper plating priming according to claim 5, wherein: the activating solution comprises the following preparation raw materials: persulfate, nitrate II, inorganic base and organic phosphonate IV; preferably, the activating and activating solution is prepared from the following raw materials in parts by weight: persulfate 2-6%, nitrate II 1-5%, inorganic base 10-20%, organic phosphonate IV 1-5% and water for the rest.

8. The method for cyanide-free copper plating priming according to claim 5, wherein: the zinc dipping solution comprises the following preparation raw materials: zinc-containing compounds, acetates, pyrophosphates, fluorides, aminoacetates and nitrates III; preferably, the zinc dipping solution comprises the following raw materials in parts by weight: 3 to 5 percent of zinc-containing compound, 1.5 to 3 percent of acetate, 4 to 7 percent of pyrophosphate, 0.1 to 1 percent of villiaumite, 0.2 to 2 percent of aminoacetate, 0.2 to 2 percent of nitrate III and the balance of water.

9. The method for cyanide-free copper plating priming according to claim 1, characterized in that:

the presoaking comprises the following process conditions:

the temperature is 15-30 ℃; the pH value is 8.5-10.0; the time is 10s to 30 s;

preferably, the preplating of the cyanide-free copper comprises the following process conditions:

the temperature is 15-30 ℃; the pH value is 8.5-10.0; the current is 1.5A/dm²～3A/dm²(ii) a The time is 5min to 10 min;

preferably, the cyanide-free copper plating comprises the following process conditions:

the temperature is 45-60 ℃; the pH value is 8.5-10.0; the current is 1.5A/dm²～2.5A/dm²(ii) a The time is 10min to 20 min.

10. The method for cyanide-free copper plating priming according to claim 1, characterized in that: the magnesium alloy is magnesium-lithium alloy.

Technical Field

The invention relates to the technical field of magnesium alloy material corrosion prevention, in particular to a cyanide-free copper plating bottoming method.

Background

The magnesium alloy is known as a green metal structural material in the 21 st century, has low density, high specific strength and specific stiffness, and excellent damping property, machinability and casting performance, and is increasingly widely applied to a plurality of fields such as automobile manufacturing, aerospace industry, electronic communication and the like.

The magnesium-lithium alloy is the lightest metal structure material in the magnesium alloy researched so far, not only has various advantages of the magnesium alloy, but also has the characteristics of outstanding shock absorption performance, strong high-energy particle penetration resistance, good machining and cold forming performance and the like, can meet the requirements of modern society on light materials, and has wider application prospect in the fields of aerospace, communication, weapon equipment manufacturing and 3C products.

The standard electrode potential of magnesium is-2.38V, the standard electrode potential of lithium is-3.05V, and the activity of the magnesium-lithium alloy is higher than that of other magnesium alloys, so that the magnesium-lithium alloy is extremely easy to corrode in air. The research of magnesium-lithium alloy in the related art focuses on the performance of the material, and the published reports of the research on corrosion resistance of the surface of the material are few, and the research on the application of the surface metallization electroplating process is less. Compared with general coating protection, the surface metallization has the advantages of high coating hardness, good wear resistance, excellent metal texture and high temperature resistance, and the special electroplating coating can achieve the effects of radiation resistance, electromagnetic shielding and the like, so that the metallization electroplating on the magnesium-lithium alloy is an indispensable surface treatment technology for industrial application.

In the related technology, the electroplating process of the traditional magnesium alloy is directly applied to the electroplating process of the magnesium-lithium alloy, which is the most common corrosion prevention, and mainly is a pre-plating process of cyanide copper plating after zinc immersion. As in the ASTM B480-88 standard established by the American society for testing and materials, a method for plating a metal coating on the surface of a magnesium alloy, namely a cyanide pre-copper plating process, is suggested. Also a Dow process, a Norskhydro process, a WCM process and the like. At present, although the cyanide pre-copper plating process of the magnesium-lithium alloy can meet the requirements of industrial application, the process uses highly toxic cyanide, has great harm to human health and pollutes the environment, does not accord with environmental protection development, and is inevitably eliminated.

In order to avoid the problems of harm to human health and environmental pollution caused by the use of cyanide, priming processes such as chemical nickel, neutral electronickelling, cyanide-free copper plating and the like are developed in the related technology.

The chemical nickel priming process has the advantages that: the process avoids the use of cyanide, has strong covering and deep plating capability of the chemical nickel priming coat, and is suitable for workpieces with different shapes and complexity. However, the process uses an organic solvent and chromic anhydride for pretreatment, so that the process has great harm to human bodies and environmental protection, the chemical nickel plating solution is a thermodynamically unstable system, the service life of the plating solution is short, the chemical nickel plating time is long, high-temperature baking heat treatment is often needed to improve the binding force in the follow-up process, the process is complicated, the cost is high, and the development of industrial application is not facilitated.

The neutral nickel electroplating priming process has the advantages that the neutral nickel is directly electroplated after zinc dipping without chemical nickel treatment, so that the compact and good-binding-force appearance is obtained, the time consumption of the process is shortened, and the production cost is reduced. However, in the process, chromic anhydride is also used for acid washing, so that the environmental pollution is great, the walking potential difference exists in the process of plating neutral nickel priming, the low current region cannot cover a plating layer, and the process is not suitable for workpieces with complicated shapes, and the industrial application development of the workpieces is limited.

The cyanide-free copper plating priming process has the advantages of avoiding the use of cyanide, along with simple flow and good coating covering capacity in a low-voltage area. But is unsafe and does not meet the requirement of environmental protection; when the method is applied to the magnesium-lithium alloy material, various problems exist, on one hand, because the potential of the magnesium-lithium alloy electrode is lower, the displacement reaction is too fast during zinc dipping, and a zinc layer is rough, on the other hand, serious copper displacement reaction is generated during non-cyanide copper electroplating, a coating with good binding force cannot be obtained, and particularly, the binding force is unqualified in a thermal shock test, and the requirement of industrial application cannot be met.

Therefore, it is necessary to develop a method for bottoming a cyanide-free copper plating, which can produce a plating layer having good adhesion.

Disclosure of Invention

In order to solve the problems in the prior art, the invention provides a cyanide-free copper plating priming method, and a plating layer prepared by the method has good bonding force.

The invention provides a cyanide-free copper plating bottoming method, which comprises the following steps:

pretreating, pre-soaking and pre-plating a magnesium alloy with cyanide-free copper and cyanide-free copper plating;

the pre-plating non-cyanide copper plating solution comprises the following preparation raw materials:

copper salt I, organic phosphonate I, polyene polyamine compound I, carbonate I, sulfenyl hybrid compound I and cycloalkyl sulfonate I;

the cyanide-free copper plating solution comprises the following preparation raw materials:

copper salt II, organic phosphonate II, polyene polyamine compound II, carbonate II, sulfenyl hybrid compound II, cycloalkyl sulfonate II and unsaturated alkoxy ether.

The bottoming method of cyanide-free copper plating is formed by three procedures of pre-dipping, pre-plating of cyanide-free copper plating and cyanide-free copper plating, wherein the pre-dipping aims at neutralizing and adjusting the pH value of the surface of a zinc dipping layer and forming a complexing agent film-protecting layer, and the speed of copper replacement of the zinc dipping layer in the pre-plating cyanide-free copper liquid medicine is delayed. Effectively solves the problem that the zinc layer is quickly subjected to displacement reaction in the pre-plating non-cyanide copper liquid medicine to generate a loose copper plating layer so as to influence the bonding force of the plating layer. Copper salt I in the preplating non-cyanide copper plating solution provides copper metal; the organic phosphonate I plays a main complexing role on copper metal, so that the plating layer is crystallized and fine, copper replacement is inhibited, and the covering capacity of the plating layer is improved; the polyene polyamine compound I has an auxiliary complexing effect on copper metal, and has a synergistic effect with a main complexing agent, so that the copper complexing stability is improved, copper replacement is further inhibited, and corrosion of a magnesium alloy material is inhibited; the carbonate I plays a role of conductive salt, increases the conductivity of the plating solution and has the pH buffering capacity; the sulfur-based hybrid compound I is a displacement agent: the coverage performance of a low region of a plating layer is improved; the naphthenic base sulfonate I is a softening agent: the internal stress of the copper plating layer is reduced, and the binding force between the copper layer and the bottom material is enhanced.

Copper salt II in the cyanide-free copper plating solution provides copper metal; the organic phosphonate II plays a main complexing role on copper metal, so that the crystallization of a plating layer is refined, copper replacement is inhibited, and the plating solution is stabilized; the polyene polyamine compound II plays an auxiliary complexing role on copper metal, has a synergistic effect with a main complexing agent, improves the copper complexing stability, further inhibits copper replacement and inhibits the corrosion of a magnesium alloy material; the carbonate II plays a role of conductive salt, increases the conductivity of the plating solution and has the pH buffering capacity; the sulfur-based hybrid compound II is a displacement agent: the coverage performance of a low region of a plating layer is improved; the naphthenic base sulfonate II is a softening agent: the internal stress of the copper plating layer is reduced, and the binding force between the copper layer and the bottom material is enhanced; unsaturated hydrocarbyloxy ethers are gloss agents: the crystallization is more delicate, and the brightness of the coating is increased.

According to some embodiments of the invention, the pre-dip, pre-dip comprises the following raw materials: organic phosphonate III and polyene polyamine III.

According to some embodiments of the invention, the pre-dip, pre-dip comprises the following raw materials: organic phosphonate III, polyene polyamine compound III and water.

According to some embodiments of the invention, the organophosphonate III comprises HEDP-Na₄(sodium hydroxyethylidene diphosphonate) and HEDP-K₄At least one of potassium (sodium hydroxyethylidene diphosphonate).

The organic phosphonate III has a slightly soluble effect on an oxide film on the surface of the zinc layer, so that the zinc layer is activated.

The polyene polyamine compound III is adsorbed on the surface of the metal zinc layer to form a complexing agent film layer, so that the zinc layer is prevented from being oxidized in the air, copper replacement is inhibited, and the binding force of a coating is improved.

According to some embodiments of the invention, the pre-dip, comprises the following raw materials prepared in parts by weight: 1 to 5 percent of organic phosphonate, 5 to 12 percent of polyene polyamine compound and the balance of water.

According to some embodiments of the invention, the pre-dip, comprises the following raw materials prepared in parts by weight: 2 to 3 percent of organic phosphonate, 8 to 10 percent of polyene polyamine compound and the balance of water.

According to some embodiments of the invention, the polyene polyamine compound iii comprises diethylenetriamine.

According to some embodiments of the invention, the pre-plating is performed without copper cyanide, and the plating solution consists of the following raw materials in parts by weight:

copper salt I, organic phosphonate I, polyene polyamine compound I, carbonate I, sulfenyl hybrid compound I, cycloalkyl sulfonate I and water.

According to some embodiments of the invention, the pre-plating is performed without copper cyanide, and the plating solution consists of the following raw materials in parts by weight:

3 to 6 percent of copper salt I;

15 to 25 percent of organic phosphonate I;

5 to 12 percent of polyene polyamine compound I;

5 to 12 percent of carbonate I;

0.01 to 0.03 percent of sulfur-based hybrid compound I;

0.1 to 0.4 percent of naphthenic base sulfonate I;

and the balance water.

According to some embodiments of the invention, the pre-plating is performed without copper cyanide, and the plating solution consists of the following raw materials in parts by weight:

4 to 5 percent of copper salt I;

18-20% of organic phosphonate I;

8 to 10 percent of polyene polyamine compound I;

8% -10% of carbonate I;

0.02 to 0.025 percent of sulfur-based hybrid compound I;

0.25 to 0.3 percent of naphthenic base sulfonate I;

and the balance water.

According to some embodiments of the invention, the cyanide-free copper plating solution consists of the following raw materials in parts by weight:

copper salt II, organic phosphonate II, polyene polyamine compound II, carbonate II, sulfenyl hybrid compound II, cycloalkyl sulfonate II, unsaturated alkoxy ether and water.

According to some embodiments of the invention, the cyanide-free copper plating solution consists of the following raw materials in parts by weight:

6 to 10 percent of copper salt II;

18 to 28 percent of organic phosphonate II;

4 to 8 percent of polyene polyamine compound II;

5 to 12 percent of carbonate II;

0.02 to 0.05 percent of sulfur-based hybrid compound II;

0.2 to 0.5 percent of naphthenic base sulfonate II;

0.01 to 0.03 percent of unsaturated alkoxy ether;

and the balance water.

According to some embodiments of the invention, the cyanide-free copper plating solution consists of the following raw materials in parts by weight:

7 to 8 percent of copper salt II;

20 to 24 percent of organic phosphonate II;

5 to 6 percent of polyene polyamine compound II;

8% -10% of carbonate II;

0.03 to 0.04 percent of sulfur-based hybrid compound II;

0.3 to 0.4 percent of naphthenic base sulfonate II;

0.02 to 0.025 percent of unsaturated alkoxy ether;

and the balance water.

According to some embodiments of the invention, the copper salt i and the copper salt ii are each independently selected from at least one of copper chloride, copper sulfate and copper nitrate.

According to some embodiments of the invention, the organophosphonate I and the organophosphonate II are each independently selected from HEDP-Na₄(sodium hydroxyethylidene diphosphonate) and HEDP-K₄At least one of potassium (sodium hydroxyethylidene diphosphonate).

According to some embodiments of the invention, the polyene polyamine-based compound i comprises diethylenetriamine.

According to some embodiments of the invention, the polyene polyamine compound ii comprises diethylenetriamine.

According to some embodiments of the invention, the carbonate salt i comprises at least one of sodium carbonate and potassium carbonate.

According to some embodiments of the invention, the carbonate ii comprises at least one of sodium carbonate and potassium carbonate.

According to some embodiments of the invention, the sulfur-based hybrid compound I comprises 2-mercaptobenzothiazole.

According to some embodiments of the invention, the sulfur-based hybrid compound II comprises 2-mercaptobenzothiazole.

According to some embodiments of the invention, the cycloalkylsulfonate I comprises sodium benzenesulfinate.

According to some embodiments of the invention, the cycloalkyl sulfonate II comprises sodium benzene sulfinate.

According to some embodiments of the invention, the unsaturated hydrocarbyloxy ether comprises propargyl alcohol propoxy ether.

According to some embodiments of the invention, the pre-treatment comprises the steps of: acid etching, activating and zinc dipping the magnesium alloy.

Acid etching, activation and zinc dipping used in the pretreatment of the invention are all specific to the characteristics of the magnesium-lithium alloy material, the surface of the magnesium-lithium alloy is effectively cleaned and activated by adjusting the formula components and the operating conditions of each procedure, a delicate zinc layer with excellent binding force is obtained in the zinc dipping, the uniform coverage with a subsequent priming copper layer is ensured, and an electroplated layer with excellent binding force can be obtained.

According to some embodiments of the invention, the acid etching solution comprises the following preparation raw materials: inorganic acid, organic phosphonic acid compound and nitrate I.

According to some embodiments of the invention, the inorganic acid comprises at least one of phosphoric acid and nitric acid.

The inorganic acid dissolves the metal oxide and impurities, promoting the activation of the metal surface.

According to some embodiments of the invention, the organic phosphonic compound comprises hydroxyethylidene diphosphonic acid (HEDP).

The organic phosphonic acid compound promotes the activation of the metal surface, has complexing effect on the metal and improves the stability of the solution.

According to some embodiments of the invention, the nitrate salt i comprises at least one of sodium nitrate and potassium nitrate.

Nitrate I promotes the oxidation and dissolution of surface impurities.

According to some embodiments of the invention, the acid etching solution is prepared from the following raw materials: inorganic acid, organic phosphonic acid compound, nitrate I and water.

According to some embodiments of the invention, the acid etching solution comprises the following raw materials by weight: 0.5 to 2.5 percent of inorganic acid, 0.8 to 3 percent of organic phosphonic acid compound, 0.05 to 0.5 percent of nitrate I and the balance of water.

According to some embodiments of the invention, the acid etching solution comprises the following raw materials by weight: 1 to 2 percent of inorganic acid, 1.2 to 2.5 percent of organic phosphonic acid compound, 0.1 to 0.3 percent of nitrate I and the balance of water.

According to some embodiments of the invention, the activating solution consists of the following raw materials in parts by weight: persulfate, nitrate II, inorganic base and organic phosphonate IV.

According to some embodiments of the invention, the activating, activating solution consists of the following preparation starting materials: persulfate, nitrate II, inorganic base, organic phosphonate IV and water.

According to some embodiments of the invention, the persulfate salt comprises at least one of sodium persulfate and potassium persulfate.

Potassium persulfate is used as a main activator: mainly plays a role in dissolving and alloying metal oxides on the surface and cleaning the surface.

The inorganic base forms a hydroxide with magnesium, inhibiting corrosion of magnesium.

According to some embodiments of the invention, the nitrate II comprises at least one of sodium nitrate and potassium nitrate.

Nitrate ii acts as an auxiliary activator: has synergistic action with persulfate, so that the oxide of the metal impurities on the surface can be removed more completely and cleanly, and the surface is activated into grey white.

According to some embodiments of the invention, the organophosphonate IV comprises HEDP-Na₄(sodium hydroxyethylidene diphosphonate) and HEDP-K₄At least one of potassium (sodium hydroxyethylidene diphosphonate).

The organic phosphonate IV and the gluconate have complexation effect on metal, and the stability of the solution is improved.

According to some embodiments of the invention, the inorganic base comprises at least one of sodium hydroxide and potassium hydroxide.

According to some embodiments of the invention, the activating solution consists of the following raw materials in parts by weight: persulfate 2-6%, nitrate II 1-5%, inorganic base 10-20%, organic phosphonate IV 1-5% and water for the rest.

According to some embodiments of the invention, the activating solution consists of the following raw materials in parts by weight:

3 to 5 percent of persulfate, 2 to 3 percent of nitrate II, 12 to 16 percent of inorganic base, 2 to 3 percent of organic phosphonate IV and the balance of water.

According to some embodiments of the invention, the zinc dipping solution comprises the following preparation raw materials: zinc-containing compounds, acetates, pyrophosphates, fluorides, aminoacetates and nitrates III.

According to some embodiments of the invention, the zincate solution is composed of zinc-containing compound, acetate, pyrophosphate, fluoride, aminoacetate and nitrate III and water.

According to some embodiments of the invention, the zinc-containing compound comprises at least one of zinc sulfate, zinc chloride and zinc nitrate.

The zinc-containing compound provides the element zinc.

According to some embodiments of the invention, the acetate salt comprises at least one of sodium acetate and potassium acetate.

Acetate is a pH buffering agent and plays a role in stabilizing the pH of the zinc dipping solution.

According to some embodiments of the invention, the pyrophosphate salt comprises at least one of sodium pyrophosphate and potassium pyrophosphate.

Pyrophosphate is the main complexing agent, which plays the roles of dissolving metal oxide, promoting the replacement reaction of zinc, complexing metal and improving the stability of the zinc dipping solution.

According to some embodiments of the invention, the fluoride comprises at least one of ammonium bifluoride, sodium bifluoride, potassium bifluoride, sodium fluoride, potassium fluoride and ammonium fluoride.

The fluoride inhibits excessive corrosion of magnesium and refines the zinc layer.

According to some embodiments of the invention, the glycine salt comprises at least one of sodium glycine and potassium glycine.

The glycine salt has the function of refining the zinc layer crystal and controls the thickness of the zinc layer.

According to some embodiments of the invention, the nitrate salt iii comprises at least one of sodium nitrate and potassium nitrate.

Nitrate III dissolves surface impurities and oxides, and promotes metal surface activation under the synergistic action of the nitrate III and a main complexing agent.

According to some embodiments of the invention, the zinc dipping solution is composed of the following raw materials by weight:

3 to 5 percent of zinc-containing compound, 1.5 to 3 percent of acetate, 4 to 7 percent of pyrophosphate, 0.1 to 1 percent of villiaumite, 0.2 to 2 percent of aminoacetate, 0.2 to 2 percent of nitrate III and the balance of water.

According to some embodiments of the invention, the zinc dipping solution is composed of the following raw materials by weight:

4 to 4.5 percent of zinc-containing compound, 2 to 2.5 percent of acetate, 5 to 6 percent of pyrophosphate, 0.3 to 0.8 percent of villiaumite, 0.5 to 1 percent of aminoacetate, 0.5 to 1 percent of nitrate III and the balance of water.

The prepreg according to some embodiments of the invention comprises the following process conditions:

the temperature is 15-30 ℃; the pH value is 8.5-10.0; the time is 10s to 30 s.

According to some embodiments of the invention, the pre-plating of the non-cyanide copper comprises the following process conditions:

the temperature is 15-30 ℃; the pH value is 8.5-10.0; the current is 1.5A/dm²～3A/dm²(ii) a The time is 5min to 10 min.

The pre-plating cyanide-free copper process reduces the operation temperature to 15-30 ℃, improves the ratio of the complexing agent to the metal, obviously reduces the speed of copper replacement, greatly improves the binding force of a plating layer, simultaneously improves the deep plating capacity of the plating layer, and obtains the plating layer with good coverage.

According to some embodiments of the invention, the cyanide-free copper plating comprises the following process conditions:

the temperature is 45-60 ℃; the pH value is 8.5-10.0; the current is 1.5A/dm²～2.5A/dm²(ii) a The time is 10min to 20 min.

The cyanide-free copper plating process utilizes high current efficiency and excellent covering performance to quickly increase the thickness of a copper layer, effectively protects the material from being eroded by acidic liquid medicine during subsequent electroplating, and ensures the binding force of a plating layer. The electroplating priming process can obtain a coating with uniform coverage and excellent binding force on the magnesium alloy workpiece in a wider operation range, meets the binding force requirement of thermal shock tests of various coatings with high thickness, has simple process flow and short priming coating plating time, and improves the efficiency of industrial production and the yield of products.

According to some embodiments of the invention, the cyanide-free copper plating comprises the following process conditions:

the temperature is 45-60 ℃; the pH value is 8.5-10.0; the current is 1.5A/dm²～2.5A/dm²(ii) a The time is 10min to 20 min.

According to some embodiments of the invention, the magnesium alloy is a magnesium lithium alloy.

The invention has at least the following beneficial effects:

the invention adopts a bottoming method of cyanide-free copper plating consisting of three procedures of presoaking, preplating cyanide-free copper plating and cyanide-free copper plating, wherein the presoaking is mainly used for neutralizing and adjusting the pH value of the surface of a zinc dipping layer, and a complexing agent protective film layer is formed, so that the zinc dipping layer is prevented from being directly contacted with copper metal in the liquid medicine of the preplating cyanide-free copper plating by the protective film layer, and the copper replacement reaction speed is reduced; when the non-cyanide copper is preplated, the operation temperature is reduced, and the two complexing agents are combined according to a certain proportion and are mutually synergistic, so that the occurrence of copper replacement reaction is further inhibited, the aim that the zinc-impregnated layer is not replaced by copper in the preplating non-cyanide copper liquid medicine for 20 seconds is fulfilled, the surface of the zinc layer has enough time for copper to be electrolytically coated, and a well-covered, uniform and fine copper coating is obtained; the cyanide-free copper plating solution utilizes high current efficiency and excellent covering performance to rapidly increase the thickness of a copper layer so as to effectively protect the material from being eroded by acidic liquid medicine during subsequent electroplating and ensure the stability of the binding force of a plating layer.

Drawings

Fig. 1 shows a magnesium-lithium alloy material according to an embodiment of the present invention.

Detailed Description

The concept and technical effects of the present invention will be clearly and completely described below in conjunction with the embodiments to fully understand the objects, features and effects of the present invention. It is obvious that the described embodiments are only a part of the embodiments of the present invention, and not all embodiments, and those skilled in the art can obtain other embodiments without inventive effort based on the embodiments of the present invention, and all embodiments are within the protection scope of the present invention.

The magnesium-lithium alloy test material selected in the embodiment of the invention is as follows:

the LZ-91 magnesium-lithium alloy is 320mm multiplied by 240mm, the thickness of a certain brand 13-inch notebook shell is 0.4 mm-0.6 mm, and the appearance is shown in figure 1.

Element(s)

Mg

Li

Zn

Si

Mn

Other impurities

Content (%)

Balance of

8.0～10.0

0.5～1.0

<0.2

<0.2

<0.3

The electroplating process flow in the embodiment of the invention is as follows:

degreasing → acid etching → activation → zinc dipping → presoaking → preplating cyanide-free copper → cyanide-free copper plating → acid copper → semigloss nickel → all gloss nickel.

Wherein, the acid etching and the activation need to be repeatedly processed for 1 to 2 times, so that the surface impurities are thoroughly and cleanly processed, and the bonding force of the subsequent plating layer can be obviously improved.

Water washing is needed for 2 times between each step (except for the steps from preimpregnation to cyanide-free copper plating, water washing is not needed between the three steps).

And sulfuric acid with the mass fraction of 8-10% is used among acid copper, semi-gloss nickel and all-gloss nickel for neutralization and activation.

The function, formulation and operating conditions of the processes in the embodiments of the present invention are shown in table 1.

TABLE 1 Effect, formulation and operating conditions of the Processes in the practice of the invention

The additives (RP-980MU, RP-980A, RP-980B, RN-3110MU, RN-3110A, RN-664, RN-781, RN-672PT, RN-664, RN-781, RN-672PT and RN-664) in the steps of copper sulfate, semigloss nickel and all gloss nickel are all commercially available from Rui corporation.

The density of the acid etching solution used in the acid etching in the embodiment of the invention is 1.05 g/mL-1.06 g/mL.

The density of the activating solution used for activation in the embodiment of the present invention is 1.14g/mL to 1.16 g/mL.

The density of the zinc dipping solution used in the zinc dipping in the embodiment of the invention is 1.10 g/mL-1.12 g/mL.

The density of the prepreg used in the prepreg according to the embodiment of the present invention is 1.08 to 1.10 g/mL.

The density of the plating solution used in the pre-plating of the non-cyanide copper in the embodiment of the invention is 1.15 g/mL-1.20 g/mL.

The density of the plating solution used in the cyanide-free copper plating in the embodiment of the present invention is 1.15g/mL to 1.20 g/mL.

The process conditions in the electroplating process of the invention in examples 1-3 are shown in Table 2.

TABLE 2 Process conditions in electroplating Processes in examples 1 to 3 of the present invention

Note: example 2 median calculation example: the concentration (g/L) of sodium hydroxide in the oil removing process is as follows: (20+50)/2 ═ 35).

Comparative example 1

This comparative example is a copper plating process.

The process conditions of the pretreatment step and the subsequent plating of this comparative example were the same as those of example 2, except that this comparative example did not have a preliminary immersion step.

Comparative example 2

This comparative example is a copper plating process.

The process conditions of the pretreatment step and the subsequent electroplating of this comparative example were the same as those of example 2, except that this comparative example did not have a pre-plating non-copper cyanide process.

Comparative example 3

This comparative example is a copper plating process.

The process conditions of the pretreatment step and the subsequent plating of this comparative example were the same as those of example 2, except that this comparative example did not have a cyanide-free copper plating process and the plating time of the preplating cyanide-free copper process was 15 min.

Comparative example 4

This comparative example is a copper plating process.

The process flow of the comparative example is as follows:

deoiling → acid etching → activation → zinc dipping → cyaniding copper plating → cyanide-free copper plating → acid copper → semigloss nickel → all gloss nickel; the oil removal, acid pickling, activation and zinc impregnation were the same as in example 2, the copper cyanide plating step was carried out using DOW (DOW) process, the copper cyanide plating formulation and operating conditions were as follows:

cuprous cyanide of about 40g/L, potassium cyanide of about 68g/L, potassium fluoride of about 30g/L, pH of about 10, temperature of about 60 ℃, cathode current density: 2A/dm²(ii) a The electroplating time is 8 min.

The process conditions for the subsequent electroplating were the same as in example 2.

The method for detecting the binding force of the plating layers prepared in the embodiments 1-3 and the comparative examples 1-4 comprises the following steps:

the method adopts a file test method, a bending test method and a thermal shock test method in GB/T5270-2005 to test, and the total thickness of the electroplated layer is 20-40 mu m.

File test method: the edge of the workpiece was filed at an angle of 45 degrees to the plating surface in the direction from the base metal to the plating coat until the base metal was visible, and whether the plating coat could be peeled off from the base was observed.

Evaluation method: "o" indicates no peeling and good bonding force; "Δ" indicates chip detachment with general cohesion; "X" indicates sheet peeling and the bonding force is poor.

Bending test method: the workpiece is bent by hand to one side for 90 degrees and then to the other side for 90 degrees until the workpiece is bent and broken, and whether the coating at the broken position can be peeled is observed.

Evaluation method: "o" indicates no peeling and good bonding force; "Δ" indicates chip detachment with general cohesion; "X" indicates sheet peeling and the bonding force is poor.

Thermal shock test method: and (3) baking the electroplated workpiece at 200 ℃ for 60min, taking out the workpiece, immediately putting the workpiece into normal-temperature water for quenching, and repeatedly testing for 3 times. The plating layer was observed for bubbling or flaking.

Evaluation method: "o" indicates no bubbling and good binding force; "Δ" indicates local blistering with general cohesion; "X" indicates severe foaming and poor binding.

The results of the performance tests of the coatings prepared in examples 1 to 3 and comparative examples 1 to 4 of the present invention are shown in Table 3.

Table 3 results of the performance test of the plating layers prepared in examples 1 to 3 of the present invention and comparative examples 1 to 4.

From table 3, it is known that, in the bonding force results of the plating layers prepared in examples 1 to 3 and comparative examples 1 to 4 of the present invention and the magnesium-lithium alloy substrate, the plating bonding force performance of the process of the present invention is the best for the magnesium-lithium alloy material, and the combination of the pre-dipping, the pre-plating of the non-cyanide copper plating and the non-cyanide copper plating has a synergistic effect with the comparative examples 1 to 3; compared with the comparative example 4, the performance of the coating bonding force of the copper plating alloy can reach the cyanide copper plating process, completely meet the requirements of industrial application and meet the requirements of environmental protection.

The invention is a cyanide-free copper plating priming process which is specially researched and developed aiming at the characteristics of a magnesium-lithium alloy material, the process comprises four procedures of oil removal, acid etching, activation and zinc immersion of pretreatment, then a cyanide-free copper plating priming method consisting of three procedures of presoaking, preplating cyanide-free copper and cyanide-free copper plating is adopted, and then the subsequent required plating layer electroplating such as acid copper electroplating, semi-gloss nickel electroplating, all-gloss nickel electroplating, trivalent chromium electroplating and the like can be directly carried out.

Acid etching, activation and zinc dipping used in the pretreatment are specially optimized by adjusting formula components and operating conditions of each procedure according to the characteristics of the magnesium-lithium alloy material, so that the surface of the magnesium-lithium alloy is effectively cleaned and activated, a fine zinc layer with excellent binding force is obtained in the zinc dipping, and the zinc layer is ensured to be uniformly covered with a subsequent priming copper layer, so that an electroplated layer with excellent binding force can be obtained.

The bottoming method of cyanide-free copper plating is formed by three procedures of presoaking, preplating cyanide-free copper plating and cyanide-free copper plating, wherein the presoaking is mainly used for neutralizing and adjusting the pH value of the surface of a zinc dipping layer, and a complexing agent protective film layer is formed, so that the zinc dipping layer is prevented from being directly contacted with copper metal in the preplating cyanide-free copper liquid medicine, and the copper replacement reaction speed is reduced; when the non-cyanide copper is preplated, the operation temperature is reduced to 20-30 ℃, and simultaneously two complexing agents are preferably combined according to a certain proportion and are mutually synergistic, so that the occurrence of copper replacement reaction is further inhibited, the aim that a zinc dipping layer does not have copper replacement in the preplating non-cyanide copper liquid medicine for 20 seconds is fulfilled, the surface of the zinc layer has enough time to be plated with copper through electrolysis, a well-covered, uniform and fine copper plating layer is obtained, and the key for improving the bonding force of the plating layer is realized; the cyanide-free copper plating solution utilizes high current efficiency and excellent covering performance to rapidly increase the thickness of a copper layer so as to effectively protect the material from being corroded by acidic liquid medicine during subsequent electroplating and ensure the stability of the binding force of the plating layer.

The electroplating priming process provided by the invention realizes that a coating with uniform coverage and excellent binding force is obtained on a magnesium-lithium alloy workpiece under a wider operation range, meets the binding force requirement of a thermal shock test of various coatings with high thickness, has a simple process flow, has short priming coating time, and improves the efficiency of industrial production and the yield of products.

The method replaces cyanogen-containing plating solution in the related technology, meets the requirement of environmental protection trend, has wide range of process operation conditions, and is suitable for the requirement of industrial production; and the plating performance and the stability of the electroplating process are superior to those of the priming process flow in the related technology.

In conclusion, the invention adopts the bottoming method of cyanide-free copper plating consisting of three procedures of pre-dipping, pre-plating cyanide-free copper plating and cyanide-free copper plating, wherein the pre-dipping is mainly used for neutralizing and adjusting the pH value of the surface of the zinc dipping layer, and a complexing agent protective film layer is formed, so that the protective film layer prevents the zinc dipping layer from directly contacting with copper metal in the pre-plating cyanide-free copper liquid medicine, and the copper replacement reaction speed is reduced; when the non-cyanide copper is preplated, the operation temperature is reduced, and the two complexing agents are combined according to a certain proportion and are mutually synergistic, so that the occurrence of copper replacement reaction is further inhibited, the aim that the zinc-impregnated layer is not replaced by copper in the preplating non-cyanide copper liquid medicine for 20 seconds is fulfilled, the surface of the zinc layer has enough time for copper to be electrolytically coated, and a well-covered, uniform and fine copper coating is obtained; the cyanide-free copper plating solution utilizes high current efficiency and excellent covering performance to rapidly increase the thickness of a copper layer so as to effectively protect the material from being eroded by acidic liquid medicine during subsequent electroplating and ensure the stability of the binding force of a plating layer; the method meets the requirement of high binding force, has simple and stable process flow, and improves the yield of industrial production and the possibility of popularization.

While the embodiments of the present invention have been described in detail with reference to the description and the drawings, the present invention is not limited to the embodiments, and various changes can be made without departing from the gist of the present invention within the knowledge of those skilled in the art. Furthermore, the embodiments of the present invention and the features of the embodiments may be combined with each other without conflict.