What is the process of electroless nickel plating?

The process flow of electroless nickel plating of general steel parts and the treatment methods are as follows:

1. Degreasing: If the degreaser is used, it should be used according to the instruction manual of the degreaser;

The self-formulated degreaser is prepared and used as follows:

Sodium hydroxide. 30-50g/l

Trisodium phosphate: 50 g l

Sodium carbonate. 30-50g/l

op-10：1-3ml/l

Temperature: 80 degrees Celsius or higher, until the oil is exhausted.

2. Cleaning: two countercurrent cleaning.

3. Rust removal and activation: 50% industrial hydrochloric acid is activated at room temperature.

4. Cleaning: two countercurrent cleaning.

5. Electroless plating: operate according to the requirements of electroless plating process.

6. Cleaning: two countercurrent cleaning.

7. Passivation: chromic acid.

30g-50g/l

Phosphoric acid: sodium fluorosilicate. 1-5 g l, cobalt sulfate.

8. Cleaning: two countercurrent cleaning.

9. Grease sealing: 1% grease soapy aqueous solution is treated at room temperature for 10-20 seconds.

10. Cleaning: two countercurrent cleaning.

11. Blow dry with compressed air.

12. Heat treatment, polishing, inspection and packaging according to customer requirements.

This is relatively simple, you can take a look at this as a reference.

Summary. The formulation of electroless nickel plating solution is: NiSO4 7H2O:

20g/l，nah2po2•h2o：30g/l，na3c6h5o7•2h2o：10g/l，nh4cl：

30g/l；pH: concentrated ammonia water adjustment).

Process flow: degreasing - activation - air plating - sand loading - floating sand removal - thickening plating - plating surface layer.

Electroless nickel plating solution is divided into acidic and alkaline two, in the acid plating solution is generated is a high phosphorus non-magnetic coating (the electroless nickel plating temperature under acidic conditions is generally 85 95), while in the alkaline plating solution is a low phosphorus magnetic coating, suitable for absorbing materials. The alkaline electroless nickel plating solution has very good homoplizing ability and high coating adhesion.

What is the electroless nickel plating formulation? How to do the process?

The formula of electroless nickel plating solution is: NiSO4 7H2O:20G L, NaH2PO2 H2O:

30g/l，na3c6h5o7•2h2o：10g/l，nh4cl：30g/l；pH:

concentrated ammonia water regulation). Process flow: degreasing - activation - air plating - sand loading - floating sand removal - thickening plating - plating surface layer.

Electroless nickel plating solution is divided into acidic and alkaline two, in the acid plating solution is generated is a high phosphorus non-magnetic coating (the electroless nickel plating temperature under acidic conditions is generally 85 95), while in the alkaline plating solution is a low phosphorus magnetic coating, suitable for absorbing materials. The alkaline electroless nickel plating solution has very good homoplizing ability and high coating adhesion.

In the process, degreasing is generally treated by electrolysis in a solution containing sodium hydroxide, sodium carbonate and trisodium phosphate; Activation is generally carried out in hydrochloric acid or sulfuric acid, and for stainless steel matrix, pre-plating is also required; Empty plating is to first coat a layer of primer coating, so that the diamond can be better adhered to; Sand plating is to make the diamond initially adhere to the surface of the workpiece, the method has sand sprinkling, sand removal method, buried sand method, according to the shape of the workpiece selection, the current size according to the size of the sand particles and the shape of the workpiece to decide.

The so-called electroless nickel plating process, in layman's terms, is a method of depositing a layer of nickel on the surface of metal parts by redox without external current. It is used to improve corrosion resistance and abrasion resistance, increase gloss and aesthetics.

Compared with the electroplating process, electroless nickel plating is a very low pollution process, the utilization rate of nickel is high, the concentration of nickel ions in the plating solution is less than one-tenth of that of electroplating nickel, and Ni-P alloy is a good chromium substitute coating.

Thickness uniformity: uniform thickness and good uniform plating ability is a major feature of electroless nickel plating, but also one of the reasons for wide application, electroless nickel plating avoids the uneven thickness of the electroplating layer due to uneven current distribution, the thickness of the electroplating layer varies greatly in the whole part, especially the parts with complex shapes, in the corners of the parts and the parts close to the anode, the plating layer is thicker, and the plating on the inner surface or far away from the anode is very thin, or even can not be plated, the use of electroless plating can avoid this deficiency of electroplating. During electroless plating, as long as the surface of the part is in contact with the plating solution, the components consumed in the plating solution can be replenished in time, and the thickness of the coating layer in any part is basically the same as that of the waxing solution, even if the grooves, gaps, and blind holes are the same.

Therefore, at present, many users who come to nickel plating anti-rust oil still electroplating nickel more, because the thickness of this coating is not uniform, and it may be easy to rust locally when doing salt spray test in the shape bend, so it needs to be compensated by nickel plating anti-rust oil.

a.Electroless plating currently has only one color of pure nickel-phosphorus alloy on the market, while electroplating can achieve many colors. The author has met customers of all kinds of electroplating, plating all kinds of colors; Electroless plating relies on the autocatalytic reaction that occurs on the surface of the metal, and the difference between electroless plating and electroplating in principle is that electroplating requires an external current and anode.

The economic benefits of electroless nickel plating are very large. 1.As long as the plating solution can be soaked and the solute exchange is sufficient, the coating will be very uniform, and the effect of profiling can be almost achieved.

The electroless nickel process does not require external DC power equipment, there is no influence of the distribution of power lines and uniformity, and for the workpiece with complex shapes, it can also obtain a uniform thickness of the coating, and the coating is dense and the pores are few, and it can be plated on different substrates such as metal, non-gold and non-gold, half-stove blind conductors, etc.

Introduction: Electroless nickel plating is one of the fastest growing electroless plating; It can be divided into three categories: acidic, neutral and alkaline. Electroless nickel plating is the reduction of nickel ions in solution on catalytically active surfaces with a reducing agent.

The plating solution is generally nickel sulfate, nickel acetate, etc. as the main salts, phosphite, sodium borohydride, borane, hydrazine, etc. as reducing agents, and then add various additives. Work in an acidic solution of 90 or a neutral solution or alkaline solution close to room temperature. According to the different reducing agents used, it can be divided into two categories: electroless nickel plating phosphorus and electroless nickel boron.

The coating shows superiority in uniformity, corrosion resistance, hardness, weldability, magnetism, and decoration.

Principle: Under the catalytic action of catalyst iron, the hypophosphor in solution catalyzes dehydrogenation on the catalytic surface to form active hydride and is oxidized to phosphite; The reactive hydride undergoes a reduction reaction with nickel ions in solution to deposit nickel, which itself oxidizes to hydrogen. At the same time, part of the hypophosphite in the solution is reduced by hydride to elemental phosphorus into the coating.

The basic process of electroplating process is polishing, polishing, hanging, degreasing, degreasing, washing, including coarse, electrolytic polishing or chemical polishing, pickling and activation, pre-plating, electroplating, washing, post-treatment, washing, drying, hanging, inspection and packaging.

Electroplating is the process of using the principle of electrolysis to coat a thin layer of other metals or alloys on some metal surfaces, and it is a process that uses electrolysis to attach a layer of metal film to the surface of metal or other material parts, so as to prevent metal oxidation (such as rust). To improve abrasion resistance, electrical conductivity, reflectivity, corrosion resistance (copper sulfate, etc.) and aesthetics, the outer layer of many coins is also electroplated.

During electroplating, the coated metal or other insoluble materials are used as the anode, the workpiece to be plated is the cathode, and the cations of the coated metal are reduced to form a coating on the surface of the workpiece to be plated. In order to exclude the interference of other cations, and make the coating uniform and firm, it is necessary to use a solution containing the coated metal cation as the electroplating solution to keep the concentration of the metal cation of the coating unchanged. The purpose of electroplating is to coat a metal coating on a substrate to change the surface properties or dimensions of the substrate.

PlatingTypical techniques

Cyanide-free alkaline bright copper: pre-plating and thickening are completed in one step on the copper alloy, the thickness of the coating can reach more than 10 m, and the brightness is like acid bright copper plating, and if it is blackened, it can achieve a pitch black effect, and it has been operating normally in 10,000 liters tank for two years.

Cyanide-free bright silver plating: the ordinary type uses thiosulfate as the main complexing agent, and the advanced type uses sulfur-free organic matter as the main complexing agent.

Cyanide-free gold plating: The main salt of cyanide-free autocatalytic chemical gold plating adopts Na3[Au(SO3)2], and the thickness of the gold layer can reach, which has been used for gold plating on high-density flexible circuit boards and electronic ceramics. Zheng Zai.

Non-formaldehyde copper plating: non-formaldehyde autocatalytic electroless copper plating is used for through-hole plating and non-conductor surface metallization of circuit boards, eliminating toxic formaldehyde and replacing it with cheap and non-toxic hypophosphite, and there are no commercial products at home and abroad.

Pure palladium plating: Ni will cause other phenomena, the European Union has long refused to import Ni-containing jewelry, palladium is the best substitute for Ni metal.

The above content reference: Encyclopedia - electroplating.

In addition to the nine nickel plating processes, there are chloride nickel plating, fluoroborate nickel plating, oak pyrophosphate nickel plating, etc., which are less widely used.

1. Dark nickel. In addition to being used as a functional coating, it is mainly used as a primer coating for protective decorative coatings to replace the cyanide copper plating process and increase the adhesion of the plating.

2. Semi-bright nickel. By adding a small amount of sulfur-free additives with good leveling ability to the dark nickel plating solution, a semi-bright nickel plating layer with excellent leveling ability can be obtained. It is often used as an intermediate coating in a three-layer nickel process.

Since there is no sulfur in the plating, there is a potential difference of more than l20mV between its electrode and potential and the bright nickel plating (containing sulfur). This improves corrosion resistance.

3. Bright nickel. The addition of certain brighteners to the dark nickel plating solution can obtain a fully bright nickel layer similar to that of a mirror bright. It is often used on top of semi-bright nickel plating to increase its decorative properties and corrosion resistance.

Because the brightener contains sulfur organic matter, there are sulfur atoms mixed in the coating, which makes it have a certain potential difference with the bottom semi-bright nickel layer.

4. High sulfur nickel. Between semi-bright nickel and bright nickel, a layer of sulfur content is plated. The nickel layer, known as high sulfur nickel.

The chemical activity of this coating is very high, mainly used in the middle of the protective decorative coating of steel and zinc alloy matrix, due to the difference in sulfur content between the three layers of semi-bright nickel, high sulfur nickel and bright nickel, the potential difference between the two layers is reached, so that the longitudinal corrosion becomes transverse corrosion. to the purpose of delaying the corrosion of the base metal.

5. Pearl nickel (also known as satin nickel). It is a satin-like nickel-plated layer that does not reflect dazzlingly in sunlight and does not feel dizzy or tired when the human eye looks at it. This type of coating is widely used in automobile manufacturing, surgical instruments, machine tools, instrumentation and other industries.

6. Black nickel. This is a nickel plating with good matting properties. The plating contains about 40% nickel

60%, the rest is zinc, sulfur and organic matter. The hardness of this coating is harder than the passivation of galvanized black, and the wear resistance is better. It is mostly used in the manufacture of optical instruments and camera equipment.

It is also used in the manufacture of solar collectors.

7. High-stress nickel. In a specific nickel plating solution, adding an appropriate amount of additives can plating a nickel plating layer with high stress, and due to the high stress, many microcracks will be produced on the surface of this coating. A layer of ordinary chromium plating is applied to the surface of this nickel layer, which forms micro-crack chromium, and when the crack density reaches strip and cm, it will have strong corrosion resistance.

8. Nickel plating of citrate. This plating solution works under neutral pH value, and Simebi is mainly used in the electroplating priming of zinc-aluminum die-casting and aluminum parts. In order to ensure that there is a good adhesion between the plating and the base metal.

9. Nickel plating of sulfamate. A low-stress nickel layer can be obtained from this bath. It is mainly used for nickel plating in electroformed nickel or printed circuit boards before gold plating. However, the cost of this bath is higher.