CNC Mechanical Routing and Milling

CNC mechanical routing is the most widely used method for defining the physical outline of a PCB and creating internal cutouts. This method involves the use of high-speed, rotating carbide cutting tools to remove material from the board's laminate (such as FR4, Rogers, or aluminum substrates) according to your design specifications. Unlike chemical etching, which defines the copper traces, routing works by directly shaping the board's edges and internal areas.

The Routing Process at APTPCB:

• High-Speed Precision: Our multi-spindle CNC routers operate at speeds ranging from 30,000 to 100,000 RPM, ensuring precise cuts and smooth sidewalls for your boards.
• Custom Profiles and Internal Cutouts: The routing path is defined by the Gerber files provided by the customer, ensuring that each board is precisely cut to the correct shape, whether it's a standard rectangular shape or a complex, custom design.
• Tight Tolerances: The standard routing tolerance for rigid boards is ±0.10mm (±4 mil). For projects requiring higher precision, we can achieve tighter tolerances by utilizing specialized tooling and adjusting stack heights.

Key Routing Features:

• Individual Unit Routing: Ideal for complex shapes, curves, and non-rectangular PCBs. CNC routing ensures that even intricate designs are produced with high accuracy.
• Internal Cutouts and Slots: We use specific router bits (ranging from 0.8mm to 2.0mm in diameter) to create internal plated or non-plated slots, ventilation cutouts, and mechanical clearance holes.
• Breakaway Tabs (Mouse Bites): For panelized PCB assemblies, we can route most of the board outline while leaving small tabs to hold the individual boards in place. These tabs are perforated with mouse bites to facilitate easy separation after assembly.

Advantages of CNC Routing:

• Versatility in Shape: CNC routing is ideal for non-rectangular PCBs, including complex curves and internal cutouts, giving you more design flexibility.
• Highly Accurate Cuts: The high-speed routing and precise control allow for clean, smooth edges and detailed features, ensuring a reliable fit and high performance in your applications.
• Perfect for Prototyping and Low-Volume Production: This method is ideal for small batches or custom designs, as it allows for rapid prototyping and quick turnaround times.

V-Scoring (V-Cut) Panelization

V-Scoring (also known as V-Cut or V-Groove) is an efficient and highly cost-effective profiling method used in high-volume surface mount assembly (SMT) processes. This technique involves cutting a triangular groove into the top and bottom surfaces of the PCB panel, leaving a thin web of material to hold the boards together. V-scoring is particularly useful when a rectangular PCB layout is used and allows for easy separation after assembly.

How V-Scoring Works:

• Automated V-Scoring Machines: At APTPCB, we utilize automated V-cut machines with diamond-coated blades that cut from both sides of the panel simultaneously. This ensures perfect alignment and precision.
• Depth Control: The depth of the V-cut is tightly controlled, typically leaving about 1/3 of the board thickness as a web. This provides the board with enough structural integrity during assembly but allows for easy manual or automated separation during the depaneling process.

Design Constraints for V-Scoring:

• Straight Lines Only: V-scoring is suitable for square or rectangular PCBs only. It cannot be used for non-rectangular or irregular shapes.
• Jump Scoring: In certain special cases, jump scoring can be used to skip over sections of the panel. However, this process increases time and cost and is less efficient for large runs.
• Clearance for Copper Features: For the V-scoring to work effectively, copper features and components must be placed at least 0.4mm away from the V-cut line to prevent damage during the separation process.

Advantages of V-Scoring:

• Material Efficiency: V-scoring maximizes the use of board space by placing boards edge-to-edge in a panel, minimizing waste and lowering the cost per unit.
• Rigid Panel for Automated Conveyors: The cut provides a rigid panel structure, making it ideal for automated assembly lines where the panel needs to withstand the mechanical handling of the board.
• Cost-Effective for High-Volume Production: This method significantly reduces costs for high-volume production due to its efficiency and minimal material wastage.

Laser Depaneling and Singulation

As electronic components shrink and PCBs become thinner or more flexible, laser depaneling has emerged as a superior, stress-free alternative to traditional mechanical methods. This process uses a focused laser beam to vaporize PCB material, offering a non-contact method that eliminates the risk of mechanical stress associated with traditional methods like routing or V-scoring.

Laser Ablation Technology:

• Non-Contact Process: Laser depaneling uses high-energy light to vaporize the PCB material without any physical contact. This is particularly beneficial for fragile components like ceramic capacitors or sensitive solder joints.
• UV and CO2 Lasers: At APTPCB, we utilize both UV lasers (ideal for cold ablation) and CO2 lasers (for thicker materials). UV lasers are preferred for clean cuts with minimal heat damage and no charring, making them perfect for high-precision applications.

Advantages of Laser Profiling:

• Zero Mechanical Stress: Since there is no physical contact with the board, laser depaneling ensures that sensitive components and solder joints are not subjected to any mechanical stress, preventing potential damage.
• Ability to Cut Complex Geometries: Laser systems are ideal for cutting intricate shapes, complex contours, and fine radii that traditional router bits cannot achieve.
• Extremely Narrow Kerf: The laser cutting width (kerf) is exceptionally narrow, typically 20-50 microns, which helps maximize board real estate.
• Ideal for Rigid-Flex and Flexible PCBs: Laser cutting is the preferred method for cutting Flexible Printed Circuits (FPC) and coverlay materials, as mechanical routers can tear polyimide films.

Quality Control and Dimensional Verification

At APTPCB, we prioritize precision in every step of the PCB profiling process. After the profiling is completed, we conduct thorough dimensional verification to ensure the final PCB meets the required specifications. Our stringent quality control processes include the use of Automated Optical Inspection (AOI) and Coordinate Measuring Machines (CMM) for precise measurements.

Key Inspection Areas:

• Overall Length and Width: Ensuring that the board fits perfectly into the specified enclosure or casing.
• Slot Width and Position: Verifying that the mechanical connectors and components will align correctly.
• V-Cut Web Thickness: Ensuring that the panel is neither too fragile to handle nor too difficult to separate.

Edge Quality:

• Smooth Sidewalls: For routed boards, we check for smooth sidewalls free from burrs or debris.
• Alignment of Cuts: For V-scored boards, we verify perfect alignment of cuts from both sides.
• Carbonization Levels: For laser cuts, we ensure the edges are clean with minimal carbonization.

• Choose CNC Routing if: You need complex shapes, internal cutouts, or non-rectangular designs, and require very smooth edges.
• Choose V-Scoring if: Your board is rectangular, you're running high-volume production, and you want to minimize material costs.
• Choose Laser Depaneling if: You need precision cuts, are working with Rigid-Flex PCBs, or have sensitive components near the edges of the board.