What distinguishes an alkaline copper electrolyte from an acidic one?

In electroplating, there are two main types of copper electrolytes: alkaline and acidic. They differ in their composition, pH value, and the properties of the deposited copper layers.

Differences between alkaline and acidic copper electrolytes:

pH value:

• Alkaline copper electrolyte: Has a high pH value (basic), often based on salts like copper cyanide or copper sulfate, with complexing agents added for stabilization.
• Acidic copper electrolyte: Has a low pH value (acidic) and is typically based on copper sulfate and sulfuric acid.

Deposition properties:

• Alkaline copper electrolyte: Suitable for coating acid-sensitive materials like zinc or iron. It provides good adhesion to these materials and creates a layer that is often more ductile, meaning it can be deformed better without breaking.
• Acidic copper electrolyte: Suitable for smooth, decorative layers with a glossy surface. It is often used for large, simple metal parts and offers faster deposition and a finer crystal structure.

Use and application:

• Alkaline copper electrolyte: Commonly used for complex-shaped workpieces and for uniform deposition on various substrates, especially when good adhesion and ductility are important. It is often used in electronics, for printed circuits, and for copper plating on iron.
• Acidic copper electrolyte: Ideal for applications requiring a shiny, decorative surface and is frequently used for decorative coatings on metals, such as in the jewelry industry or for chrome-plated surfaces as a base layer.