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.
| Chemical Component | Concentration | Quantity for 1000L | Sourcing |
| Copper Sulfate Pentahydrate (CuSO₄·5H₂O) | 35 – 45 g/L | 35 – 45 kg | [Purchase Locally] |
| Potassium Hydroxide (KOH) | 50 – 70 g/L | 50 – 70 kg | [Purchase Locally] |
| [QLQ Product] NC-Base Complexing Agent | 200 – 250 ml/L | 200 – 250 Liters | [QLQ Product] |
| [QLQ Product] NC-Make Up Salt | 30 – 40 g/L | 30 – 40 kg | [QLQ Product] |
| [QLQ Product] NC-Adjuster (pH Buffer) | 10 – 15 ml/L | 10 – 15 Liters | [QLQ Product] |
| [QLQ Product] NC-Brightener | 1 – 2 ml/L | 1 – 2 Liters | [QLQ Product] |
Warning: Do NOT use Sodium Hydroxide (NaOH). Potassium (KOH) provides better conductivity and solubility for this specific non-cyanide system.
3. Operational Parameters
| Parameter | Range | Optimal |
| pH Value | 9.2 – 10.0 | 9.5 |
| Temperature | 55°C – 65°C | 60°C |
| Cathode Current Density | 0.5 – 2.0 A/dm² | 1.0 A/dm² |
| Anode Current Density | 0.5 – 1.5 A/dm² | 1.0 A/dm² |
| Voltage | 3 – 6 V | 4 V |
| Anode Material | OFHC Copper (Oxygen-Free High Conductivity) | Required |
| Agitation | Strong Mechanical Rocker or Filter Flow | No Air Agitation (Avoids oxidation) |
| Filtration | Continuous, 5–10 Microns | Required |
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.
Cleaning: Thoroughly clean the tank (leach with 5% Sulfuric Acid, then rinse).
Water: Fill the tank with Pure Water (RO) to 50% volume.
Complexing Agent: Add the [QLQ Product] NC-Base Complexing Agent and [QLQ Product] NC-Make Up Salt. Stir until fully dissolved.
Heating: Heat the solution to 50°C.
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.
pH Adjustment: Dissolve Potassium Hydroxide (KOH) and add slowly to raise the pH to 9.5.
Note: The reaction generates heat. Be careful.
Top Up: Fill water to the final volume.
Additives: Add [QLQ Product] NC-Adjuster and NC-Brightener.
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 (带电入槽)
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
Pipette 2 ml of bath sample into a flask.
Add 100ml Pure Water.
Add 10ml Ammonia water (NH₄OH) -> Solution turns dark blue.
Add PAN Indicator.
Titrate with 0.05M EDTA until color changes from Blue to Green.
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).