Equipment Introduction of Each Process in PCB Etching Line

The PCB etching line is a core production line that achieves precise removal of the substrate metal layer and forms circuit patterns. The overall process is divided into three stages: pre-treatment, etching, and post-treatment. The functions and parameters of the corresponding equipment for each process are as follows:

I. Pre-treatment Stage Equipment

1. Brush Cleaner

• Structure: Equipped with nylon brush rollers or non-woven brush rollers, combined with a high-pressure spray system.

• Function: Remove dry film residues, slight oxidation, and fingerprint oil stains on the substrate surface through physical friction plus spray of chemical cleaning fluid (weakly alkaline or acidic); some models are equipped with a water washing section to rinse and blow dry the board surface after cleaning.

• Key parameters: Brush roller speed 150–300r/min, conveying speed 1–5m/min, suitable for board thickness 0.2–3.0mm.

2. Water Washing Machine + Air Dryer

• Water Washing Machine: Adopts multi-stage countercurrent rinsing to rinse the residual brush cleaning fluid on the board surface with pure water, reducing the risk of subsequent etching solution contamination.

• Air Dryer: Equipped with high-pressure air knives or hot air knives to quickly blow dry the moisture on the board surface and avoid uneven etching caused by water stains.

II. Core Equipment of Etching Stage

1. Chemical Etching Machine

   It is the current mainstream equipment, divided into spray type and immersion type, with the spray type accounting for more than 90%.

• Structure: Composed of etching solution storage tank, spray pump, nozzle array, temperature control system, and conveying device; divided into acid etching machine (copper chloride system) and alkaline etching machine (ammonia copper system) according to the type of etching solution.

• Function: The etching solution is pressurized by the pump and forms a high-pressure fan-shaped liquid flow through the nozzle to impact the substrate surface, accelerating the dissolution of the copper layer; the temperature control system stabilizes the etching solution at 40–55℃ to ensure uniform reaction rate.

• Key configurations: Nozzle spacing 5–10cm, spray pressure 0.15–0.3MPa, conveying speed can be adjusted according to line width (0.5–2m/min for fine lines); equipped with an online copper ion concentration detector to automatically add chemicals to maintain the stability of the etching solution.

• Spray Etching Machine

• Immersion Etching Machine

  Simple structure, the substrate is immersed in the etching solution for reaction, with low cost but poor etching uniformity, only suitable for the production of low-precision single-sided boards.

2. Electrochemical Etching Machine (ECM Etcher)

• Principle: The substrate is used as the anode, and current is applied to dissolve the copper layer under the action of an electric field, which is a kind of "directional corrosion".

• Advantages: Extremely high etching precision, capable of manufacturing fine lines below 0.03mm, suitable for HDI boards and flexible boards; high regeneration efficiency of etching solution and good environmental protection.

• Limitations: High equipment cost and energy consumption, only used in high-end PCB manufacturing processes.

III. Post-treatment Stage Equipment

1. Water Washing Machine (Multi-stage Rinsing)

• Post-etching Water Washing: Rinse the residual etching solution on the board surface with pure water to prevent the residual chemical solution from continuously corroding the circuit.

• Neutralization Water Washing: If alkaline etching is adopted, a weak acid neutralizing solution (such as citric acid) is needed to neutralize the alkaline residue on the board surface, and then rinse with pure water.

• Divided into two sections: post-etching water washing and neutralization water washing:

• Features: Adopts countercurrent rinsing process, saving more than 60% of water and meeting environmental protection requirements.

2. Developing and Stripping Integrated Machine (Optional)

• Function: For substrates with dry film retained after etching, the dry film can be directly removed with alkaline stripping solution in this equipment, replacing the separate stripping process; some models integrate water washing and air drying functions.

3. Air Dryer + Drying Oven

• Air Dryer: High-pressure air knives remove surface moisture on the board surface; Drying Oven: Adopts hot air circulation (temperature 60–80℃) to completely dry the substrate and prevent circuit oxidation.

4. AOI Testing Equipment (Automatic Optical Inspection)

• Function: Scan the substrate through a high-precision camera, automatically identify etching defects (such as over-etching, under-etching, circuit breaks, burrs), and mark the defective positions to realize process yield control.

IV. Auxiliary Equipment

1. Etching Solution Regeneration System

   Matched with the etching machine, it recovers or adjusts the concentration of copper ions in the etching solution through electrolysis, extraction and other methods, realizes the recycling of the etching solution, and reduces production costs and environmental pressure.

2. Waste Gas Treatment Equipment

   Aiming at the acidic/alkaline waste gas (such as ammonia gas, hydrogen chloride) generated during the etching process, it is treated by spray tower plus activated carbon adsorption, and discharged after meeting the emission standards.