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What are the functions and roles of PCB copper sinking?

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PCB copper sinking is an important manufacturing process, its function and role mainly include the following points:


Copper deposition in the PCB hole wall deposits a thin layer of copper, so that the hole conductive, to achieve the interlayer conductive connection.

Enhanced Connection: 

Through chemical copper deposition, the bonding between the copper layer and the resin of the hole wall and the inner copper layer is enhanced, which improves the anti-peel strength.

High Temperature Resistance: 

Copper immersed PCBs can be operated continuously in high temperature environment and ensure the smooth flow of electricity.

Improvement of Reliability: 

Immersed copper can increase the reliability and stability of the PCB, extending the service life of electronic products.

The effects of different copper thicknesses on PCBs include:


Copper thickness determines the conductivity of the circuit board. Too thin a copper layer may lead to a decrease in conductivity, signal transmission attenuation or current instability; copper layer is too thick although good conductivity, but will increase the cost and weight.

Thermal Performance: 

Copper layer as the thermal conductivity of the circuit board, its thickness determines the heat dissipation effect. Too thin a copper layer may affect the effective conduction and distribution of heat, increasing the risk of overheating components.

Mechanical Strength: 

Proper copper thickness provides sufficient mechanical strength to prevent the board from bending, breaking, or cracking during use.

Cost and Weight: 

Increased copper layer thickness increases cost and weight, and the appropriate copper thickness needs to be selected based on design requirements and actual applications.

In the actual manufacturing process, it is necessary to select the appropriate copper thickness according to the design requirements of the circuit board, functional needs and cost control and other factors to consider, in order to ensure the quality and performance of electronic products. Common copper thicknesses include 17.5um (0.5oz), 35um (1oz), 70um (2oz), etc. 70% of the circuit boards use 35µm copper foil thickness. For PCBs that require high currents, 70µm copper thickness and 105µm copper thickness are used for some parts. During the design process, copper can also be laid in blank areas to assist in the heat dissipation of the PCB.


In PCB manufacturing, the purpose of the copper sinking process is to ensure that the PCB hole walls and outer surface are evenly covered with a layer of conductive copper, which lays the foundation for subsequent processes such as plating and pattern transfer. The specific role of the copper sinking process and the impact of different copper thickness can be further refined as follows:

Current Carrying Capacity: 

The thicker the copper layer, the stronger its ability to carry high currents, suitable for high power circuits.

Signal Integrity: 

The thickness of the copper layer affects the quality of the signal transmission, and a too thin copper layer may lead to signal attenuation.

Cost Factors: 

Increased copper layer thickness can lead to higher material and manufacturing costs.

Weight and Size: 

Increased copper layer thickness can also increase the weight and size of the PCB, which can pose design constraints for portable devices.

Thermal Management: 

Increased copper layer thickness can improve the thermal performance of a PCB, which can help electronic components function properly and last longer.

Manufacturing Difficulty: 

Excessively thick copper layers may increase the difficulty of processing by adding some problems in the manufacturing process, such as glue flow and thin dielectric layers.

The Role of Immersed Copper Process:

Achieve Hole Metallization: 

Immersed copper makes non-conductive hole walls become conductive, which is critical for interlayer connections in multilayer PCB boards.

Improve the Reliability of the Connection: 

Immersed copper layer can improve the peeling strength of the PCB, to ensure the long-term stable operation of the circuit.

Improved Thermal Cycling Performance: 

A good copper immersion layer reduces thermal stress and improves the durability of the PCB when it undergoes thermal cycling.

Enhanced Mechanical Properties: 

The copper layer increases the rigidity of the PCB, reducing bending and fracture during assembly and use.

When selecting the right copper thickness, the above factors need to be balanced to ensure that the PCB meets specific electrical, mechanical and cost requirements. For example, for high density boards, a thinner copper layer may be required for finer wiring and space utilization, while for power supply boards that need to carry higher currents, a thicker copper layer may be required to ensure adequate current capacity.

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