Surface Treatment

The Five Essential Elements of Electroplating

1. Cathode: The object to be plated, typically various connector terminals.
2. Anode: For a soluble anode, it is the metal to be deposited. For an insoluble anode, it is often a precious metal (such as platinum or iridium oxide).
3. Electroplating Solution: A solution containing metal ions of the desired plating material.
4. Electroplating Tank: A container designed to hold and sustain the electroplating solution, factoring in strength, corrosion resistance, and temperature tolerance.
5. Rectifier: A device that supplies the direct current (DC) power required for the electroplating process.

Objectives of Electroplating

Electroplating serves various purposes beyond aesthetics, tailored to meet specific plating requirements:

1. Copper Plating: Used as a base layer to enhance adhesion of subsequent plating layers and improve corrosion resistance.
2. Nickel Plating: Acts as a base layer to further strengthen corrosion resistance.
3. Gold Plating: Enhances electrical conductivity by reducing contact resistance and improving signal transmission.
4. Palladium-Nickel Plating: Improves electrical conductivity and signal transmission while offering better wear resistance compared to gold.
5. Tin-Lead Plating: Enhances solderability for improved joint reliability.

Reflow Tin vs. Hot Dip Tin

Definitions and Comparison:

Reflow Tin:
Reflow tin is a process that differs from traditional electroplating and is designed to enhance solderability. After the product or material is electroplated with tin, it is reheated to the melting point of tin (450°C) and then cooled. This method helps reduce internal stress, which can prevent the formation of tin whiskers.

Hot Dip Tin:
Hot dip tin plating involves immersing the product or material in molten tin at temperatures around 450°C or 232°C. A thin layer of metallic compounds, such as iron or tin alloys, forms on the surface of the material or product. For example, when parts are dipped into the molten tin, a pure tin layer compound forms on the surface.

Advantages Comparison

Reflow Tin:

1. Reflow tin plating improves the adhesion between the tin layer and the base material.
2. Components plated with reflow tin exhibit excellent corrosion resistance, offering better protection than traditionally electroplated products.
3. Reflow tin plating provides a smooth, shiny surface finish, which is very safe for food-contact equipment.
4. After reflow tin plating, the surface thickness is uniform, with a smooth and shiny appearance, making it ideal for microelectronics like miniature connectors.
5. Reflow tin plating helps eliminate internal stress, preventing tin whisker formation and reducing insertion/extraction forces. It also provides good ductility and formability for complex metal stamping parts.
6. Reflow tin plating uses lead-free tin, making it an eco-friendly plating method that complies with RoHS standards.

Hot Dip Tin:

1. Prevents rust: Especially for steel materials, hot dip tin plating prevents surface rusting.
2. Prevents oxidation: For copper and copper alloys, it prevents surface oxidation.
3. Excellent weldability: Provides excellent soldering properties for electronic components.
4. Wear and corrosion resistance: The tin-plated layer offers better wear and corrosion resistance than non-plated materials.
5. Better breathability: Offers improved breathability.
6. Better toughness and ductility compared to traditional electroplating.
7. No false stress: It avoids false stress in the plating process.
8. More cost-effective than traditional electroplating, offering a lower price.
9. Superior corrosion resistance compared to traditional electroplating.
10. Tiny breathable holes allow airflow, unlike blind holes, offering better functionality.