Spring copper plated

Spring copper plated
4.1 Properties of copper

4.2 Types of copper plating solution formula

4.3 Copper Sulfate Baths

4.4 Copper Cyanide Baths

4.5 Copper Pyrophosphate Plating Bath

4.6 Copper Fluoborate Bath

4.7 Stainless steel copper plating process

4.8 Stripping of copper plating

4.9 Copper Plating Patent Literature (US Patent)

4.10 Journal papers related to copper plating

4.1 Properties of copper

Color: rose red Atomic weight: 63.54

Atomic number: 29 Specific gravity: 8.94 Melting point: 1083°C

Boiling point: 2582℃ Brinell hardness 43-103

Resistance: 1.673 l W -cm, 20 ℃ Tensile strength: 220~420MPa

Standard potential: Cu++e- →Cu is +0.52V; Cu++ +2e-→Cu is +0.34V.

Soft and tough, good ductility, easy plastic processing, excellent electrical and thermal conductivity

Good polishing and optical rotation, easy to oxidize, especially when heated, it cannot be used as protective coating

It will react with sulfur in the air to form brown copper sulfide. It will react with carbon dioxide in the air to form a copper record.

Will form copper chloride powder with chlorine in the air

The copper plating layer has good uniformity, compactness, adhesion and polishing rotation, so it can be used as the bottom plating layer of other electroplating metals.

The plating layer can be used to prevent carburizing and copper nitride. The only practical application for the electroplating of zinc castings.

The source of copper is sufficient. Copper is easily electroplated and easy to control

The amount of copper plating is second only to nickel

4.2 Types of copper plating solution formula

Can be divided into two categories:

1. Acid copper electroplating solution:

The advantages are:

Simple ingredients, low toxicity, easy to dispose of waste liquid

Stable plating bath without heating, high current efficiency

Low price, low equipment cost, high current density, high production rate

The disadvantages are:

Coating crystals are coarse and cannot be directly plated on steel

Poor uniformity

2. Formula of copper cyanide electroplating solution:

The advantages are:

Fine coating, good uniformity

Can be plated directly on steel

The disadvantages are:

Strong toxicity, troublesome waste disposal, low current efficiency

High price, high equipment cost, low current density, low production efficiency

The plating solution is unstable and needs to be heated

With the advantages of the above two formulas, P.S generally uses cyanide copper plating solution for primer, and then uses acid copper plating solution for copper plating, especially for plating parts with thicker plating thickness.

4.3 Copper Sulfate Baths

The preparation, operation and waste treatment of copper sulfate plating bath are very economical, and can be applied to printed circuits, electronics, photogravure, electroforming, and decoration (decorative) and plastic plating (plating on plastics). Its chemical composition is simple, containing copper sulfate and sulfuric acid. The plating solution has good conductivity and poor uniformity, but there are special formulas and additives that can be improved. Steel plated parts must be primed with a copper cyanide bath or strike with nickel to avoid the formation of replacement diposits and low adhesion. Copper-plated spring

Zinc castings and other acid-sensitive metals must be fully primed to prevent corrosion by sulfuric acid. The plating bath is operated at room temperature. The anode must be high-purity rolled copper, free of oxides and phosphating (0.02 to 0.08wt%P), and copper anode nuggets can be used in titanium baskets. The anode must be added with an anode bag, the area ratio of the anode to the cathode should be 2:1, the current efficiency of the anode and the cathode can reach 100%, and the anode copper should be taken out when it is not electroplated.

4.3.1 Standard acid copper plating

(1) General formulation:

Copper sulfate 195-248 g/l

Sulfuric acid 30-75 g/l

Chloride 50-120 ppm

Current density 20-100 ASF

(2) Semibright plating: Clifton-Phillips formula

Copper Sulfate 248 g/l

Sulfuric acid 11 g/l

Chloride 50-120 ppm

Thiourea 0.00075 g/l

Wetting agent 0.2 g/l

(3) Bright plating: beaver formula

Copper sulfate 210 g/l

Sulfuric 60 g/l

Chloride 50-120 ppm

Thiourea 0.1 g/l

Dextrin 0.01 g/l

(4) Bright plating: Clifton-Phillips formula

Copper sulfate 199 g/l

Sulfuric acid 30 g/l

Chloride 50-120 ppm

Thiourea 0.375 g/l

Wolasses 0.75 g/l

4.3.2 High uniformity acid copper plating bath formula (High Throw Bath)

Used for printed circuits, drum plating and other plating applications that require high uniformity.

Copper sulfate 60-90 g/l

Sulfuric acid 172-217 g/l

Chloride 50-100 ppm

Proprietary additive   as indicated