How to Enhance Dimensional Accuracy in High-Frequency PCB Manufacturing?

In high-frequency PCB manufacturing, strictly controlling dimensional accuracy can significantly enhance product performance and ensure overall quality. From material selection to process optimization and stringent quality control, every step must be meticulously managed to achieve the goal of high-precision manufacturing.

Material Selection

Selecting high-quality raw materials is fundamental to ensuring dimensional accuracy and product performance in high-frequency PCB manufacturing. Proper selection and management of materials can enhance processing stability and optimize the electrical performance of PCBs.

1.Material Quality and Durability

·Material Uniformity

 Choose materials with uniform thickness and composition, such as FR-4 and ceramic substrates, to reduce deformation and errors.

·Heat and Chemical Resistance

Materials need to withstand high temperatures and chemical corrosion, like polyimide, to extend service life and reduce dimensional deformation.

·Mechanical Strength

Materials with high tensile strength and hardness can avoid cracks and damage, maintaining dimensional stability.

2. Dimensional Tolerance and Durability

·Thickness Precision

 Select materials with tight thickness tolerances to minimize stacking and drilling errors.

·Coefficient of Thermal Expansion (CTE)

Choose materials with a low CTE that matches the copper foil to prevent dimensional changes due to thermal expansion and contraction.

·Moisture Stability

 Use materials with low moisture absorption, such as ceramic substrates, to reduce the impact of humidity changes on dimensions.

Process Parameter Optimization

1、Etching Parameter Optimization

Etching determines the size of the traces and gaps on the circuit board. By optimizing etching parameters, such as the concentration, temperature, and etching time of the etchant, the etching rate and depth can be controlled, thus ensuring dimensional accuracy.

2、Copper Plating Parameter Optimization

Copper plating forms a conductive layer on the surface of the circuit board. By optimizing parameters such as the composition of the plating solution, current density, and plating time, the copper plating process can be precisely controlled to ensure a uniform and compliant copper layer.

3.Drilling Parameter Optimization

Drilling is a critical step in forming vias on the PCB. By selecting the appropriate drill bit and controlling drilling speed, pressure, and other parameters, the size and position of the holes can meet design requirements.

In addition to the above key process steps, many other parameters, such as image alignment and lamination parameters, need optimization.

High-Precision Processing Techniques

1. Inner Layer Registration Accuracy

Use high-precision alignment and lamination equipment to ensure accurate alignment between inner layers. Optical alignment systems can detect and adjust the position of inner layers in real-time, improving registration accuracy. Additionally, optimizing the lamination process by controlling temperature, pressure, and time ensures stable interlayer bonding and avoids adhesion failures that cause dimensional errors.

2.Drilling Precision and Positional Accuracy

Optimize drill speed, feed rate, and pressure to reduce burrs and deviations, improving drilling precision. During multilayer board drilling, employ high-precision alignment and clamping systems to ensure layer-to-layer hole alignment and prevent misalignment.

3.Cutting Precision and Positional Accuracy

Use laser cutting machines for high-precision board cutting; laser beams offer high finesse and control, reducing mechanical cutting errors. For complex shapes, CNC milling machines can precisely mill various shapes and openings under computer control, ensuring dimensional accuracy.

Stringent Quality Control and Testing Methods

1.Accuracy and Precision of Testing Equipment

·Optical Measurement

Optical measurement technologies, such as AOI, can quickly detect defects on the PCB, including open circuits, short circuits, and dimensional deviations.

·Coordinate Measuring Machine (CMM) 

CMMs can provide high-precision dimensional data, especially suitable for complex structures and high-precision requirements of PCBs.

2.Quality Checks in Every process

·Incoming Material Inspection

Conduct rigorous warehouse inspections of raw materials to ensure their thickness, uniformity, and other critical parameters meet requirements. Use high-precision measuring equipment, such as thickness gauges and optical microscopes, for material inspection.

·Process Control

Implement real-time monitoring and feedback during key process steps like etching, copper plating, drilling, and cutting. For example, during etching, detect the etching rate and depth in real-time and automatically adjust etching parameters to ensure dimensional accuracy.

·Intermediate Inspection

Perform intermediate inspections after each critical process step. For instance, after multilayer lamination and drilling, check layer alignment and hole positional accuracy to ensure the accuracy of subsequent processing.

3.Other Stringent Quality Control Measures

·Final Inspection

Conduct final inspections before shipping to ensure all dimensional and electrical performance indicators meet design requirements. Use X-ray inspection (X-Ray) and AOI systems for non-destructive testing of the PCB's internal structure and external features.

·Environmental Control

Strictly control the production environment's temperature, humidity, and cleanliness to reduce the impact of environmental factors on dimensional accuracy. Use clean rooms in critical process steps to reduce dust and impurities affecting PCB processing.

·Employee Training

 Provide strict training and assessment for operators to ensure they possess the necessary technical skills and quality awareness, enabling them to operate equipment correctly and execute quality control procedures.