Non-Cyanide Alkaline Copper Process

Advanced Non-Cyanide Alkaline Copper Process (QLQ System)

Application: Zinc Alloy Zipper Pulls, Belt Buckles, and Hardware.

Standard: REACH Compliant (Zero Cyanide).

1. Technology Overview

Unlike Cyanide Copper, which dissolves zinc chemically (cleaning it), Non-Cyanide Copper is sensitive. It relies on a strong Complexing Agent (Chelator) to hold the copper ions tightly, preventing them from reacting with the zinc substrate (Immersion Copper) which causes peeling.

The QLQ Advantage: We use a "Super-Complexing" technology that creates a bath stable enough to plate directly onto Zinc Alloy with proper activation.

2. Tank Make-up (Bath Formulation)

Note: For a 1000 Liter Tank.

• Warning: Do NOT use Sodium Hydroxide (NaOH). Potassium (KOH) provides better conductivity and solubility for this specific non-cyanide system.

3. Operational Parameters

4. Step-by-Step Make-up Procedure (SOP)

Crucial: The order of addition determines success. If you add Copper Sulfate before the Complexing Agent, it will precipitate and ruin the bath.

1. Cleaning: Thoroughly clean the tank (leach with 5% Sulfuric Acid, then rinse).

2. Water: Fill the tank with Pure Water (RO) to 50% volume.

3. Complexing Agent: Add the [QLQ Product] NC-Base Complexing Agent and [QLQ Product] NC-Make Up Salt. Stir until fully dissolved.

4. Heating: Heat the solution to 50°C.

5. Copper Addition: In a separate bucket, dissolve the Copper Sulfate in hot water.

   • Slowly add the dissolved copper into the main tank while stirring vigorously.

   • Observation: The solution should turn a deep, clear blue. If it turns cloudy, stop and add more Complexing Agent.

6. pH Adjustment: Dissolve Potassium Hydroxide (KOH) and add slowly to raise the pH to 9.5.

   • Note: The reaction generates heat. Be careful.

7. Top Up: Fill water to the final volume.

8. Additives: Add [QLQ Product] NC-Adjuster and NC-Brightener.

9. Dummy Plating: Electrolyze at low current (0.2 A/dm²) for 4-6 hours to stabilize the chemistry.

5. Critical Precautions for Zinc Alloy (Must Read)

1. The "Live Entry" Rule

• The Problem: In non-cyanide baths, if a zinc part sits in the solution without electricity, the copper will loosely deposit onto the zinc (Immersion Copper). This layer will peel off later.

• The Solution: The barrel MUST be rotating and the Rectifier MUST be ON (Preset to 2-3V) before the barrel touches the liquid. The current must hit the parts the instant they enter the water.

2. Activation is Different

• Do not use strong acid before this bath.

• Use [QLQ Product] Acid Activation Salt (Fluoride-based) for only 5-10 seconds.

• Recommendation: A "Pre-dip" in a dilute solution of [QLQ Product] NC-Base Complexing Agent (5%) before entering the plating tank helps prevent blistering.

3. Anode Maintenance

• Use OFHC Copper (Oxygen-Free). Do not use Phosphorus Copper (used for acid copper).

• Use High-Density Anode Bags (Double layer). The sludge from non-cyanide copper is very fine and causes roughness easily.

6. Analytical Control & Testing Methods

To be a professional QLQ line, you must analyze the bath twice a week.

A. Copper Content Analysis

1. Pipette 2 ml of bath sample into a flask.

2. Add 100ml Pure Water.

3. Add 10ml Ammonia water (NH₄OH) -> Solution turns dark blue.

4. Add PAN Indicator.

5. Titrate with 0.05M EDTA until color changes from Blue to Green.

6. Calculation: Copper (g/L) = ml EDTA × 3.177.

B. pH Check

• Use a high-temperature resistant pH probe.

• If pH < 9.2: Add Potassium Hydroxide.

• If pH > 10.2: Add [QLQ Product] pH Buffer Acid.

C. Hull Cell Test (Daily)

• Conditions: 1 Amp, 10 Minutes, 60°C.

• Check:

  • High Current Density Area (Left): Should be semi-bright, not burnt.

  • Low Current Density Area (Right): Must be fully covered with copper. If the zinc substrate is visible (black/grey) on the right side, you lack [QLQ Product] NC-Make Up Salt (Throwing Power).