PCB Services: Detailed Explanation of the Electroplating Process

introduction

The Printed Circuit Board (PCB) is an indispensable core component in modern electronic products. PCBs provide a platform for mounting various electronic components and realizing electrical connections through complex circuits. In the manufacturing process of PCBs, the electroplating process is a critical step. It enhances the conductivity of the PCB surface, improves solderability, effectively protects the PCB from environmental factors, and extends its lifespan.

PCB Electroplating Process

The electroplating process involves multiple steps, each crucial to the quality of the final product. Below is a detailed outline of the PCB electroplating process:

Acid Immersion:

Function and Purpose: Removes oxides from the PCB surface, activates the board surface, and ensures the smooth progression of subsequent processes. The acid concentration is typically between 5-10%, and the immersion time should not be too long to prevent re-oxidation of the board surface.

Full-Board Copper Plating:

Function and Purpose: Forms a uniform copper layer on the PCB surface to protect the previously deposited chemical copper and enhance conductivity. The plating solution mainly consists of copper sulfate and sulfuric acid, with a high-acid, low-copper formulation to ensure thickness uniformity and deep hole plating capability.

Acidic Degreasing:

Function and Purpose: Removes oxides and ink residues from the copper surface of the circuit, ensuring the adhesion of the subsequent plating. This step uses acidic degreasers to prevent damage to the circuit pattern that could occur with alkaline degreasers.

Micro-Etching:

Function and Purpose: Lightly roughens the copper surface of the circuit using chemicals like sodium persulfate, ensuring good adhesion between the initial copper plating and the subsequent copper plating.

Pattern Copper Plating:

Function and Purpose: Further increase the plated copper’s thickness to meet the circuit’s current load requirements. The process parameters used here are similar to those in full-board copper plating.

Tin Plating:

Function and Purpose: Applies a layer of pure tin on the PCB to protect the circuit pattern from the etching process. The plating solution consists of tin sulfate, sulfuric acid, and additives, with temperature controlled between 22-30°C.

Nickel and Gold Plating:

Function and Purpose: Nickel plating prevents the oxidation of the PCB’s copper layer, while gold plating ensures excellent performance during soldering. Gold-plated PCBs not only have excellent conductivity but also significantly improved corrosion resistance.

Drying:

Function and Purpose: Removes moisture from the PCB surface and inside the holes through drying, ensuring the stability and durability of the plating layer.

Process Maintenance and Optimization

Maintaining and optimizing process parameters is crucial during electroplating. Here are some key maintenance steps:

Regular Chemical Additions: Supplement copper brighteners or tin plating additives according to ampere-hours to ensure consistent plating results.
Temperature Control System: Especially during high temperatures in summer, use a cooling system to maintain the plating bath temperature within a suitable range to prevent additive decomposition due to excessive heat.
Electrolytic Cleaning: Periodically perform low-current density electrolytic cleaning to remove impurities from the plating bath, extending the life of the bath solution.
Anode Maintenance: Clean the anode conductive rods and anode bags, check for anode bag damage, and replace them promptly to ensure uniform plating.

Conclusion

The PCB electroplating process is a crucial step in ensuring the performance and lifespan of PCBs. Through scientific and reasonable process control and equipment maintenance, PCB quality can be significantly improved to meet the demand for high-performance circuit boards in electronic products. Understanding and mastering the details of each step will help increase production efficiency and product pass rates.