Castellated PCBs are specialized circuit boards designed for board-to-board solder connections in compact electronic assemblies. Instead of using traditional through-hole pins or external connectors, these PCBs use plated half-hole pads along the board edge. The exposed copper edges allow the PCB module to be directly soldered onto a main board, creating a low-profile and reliable electrical connection.
This design approach is widely used in embedded electronics where engineers need to reduce assembly size, simplify integration, and maintain reliable signal and power connections. Common examples include wireless communication modules, IoT devices, sensor boards, embedded controllers, and compact industrial electronics.
A castellated PCB typically contains a row of plated holes that are cut through the PCB edge during the manufacturing process. After routing or panel separation, each plated hole becomes a semi-circular solder pad. The final geometry must be carefully controlled because pad shape, plating quality, hole size, and edge tolerances directly affect solder joint reliability.
At Highleap PCB Factory, we manufacture castellated PCBs and other specialized circuit board solutions for applications requiring compact form factors and controlled electrical performance. Our PCB capabilities include high-density interconnect (HDI) designs, high-frequency circuits, low-profile boards, and custom PCB manufacturing for industries such as telecommunications, aerospace, medical electronics, and IoT systems.
Key Features and Benefits of Castellated PCBs
Castellated PCBs provide a practical solution for modular electronics by combining mechanical simplicity with reliable electrical performance. Their main design advantages include:
- Edge-mounted solder pads: Castellated holes create exposed solderable pads on the PCB edge, allowing the module to be mounted directly onto another circuit board. This eliminates the need for additional connectors and reduces overall assembly height.
- High-density interconnect (HDI) compatibility: Castellated PCB designs can be combined with HDI technologies such as microvias, fine traces, and compact layer structures to support advanced miniaturized electronics while maintaining signal performance.
- Space-saving integration: Removing traditional connectors reduces PCB footprint and mechanical complexity. This makes castellated designs suitable for small wireless modules, wearable devices, sensors, and embedded control systems.
- Reliable board-to-board assembly: Properly manufactured castellated pads provide strong solder connections between the module PCB and the host board, improving mechanical stability compared with some removable connector solutions.
- Design flexibility: Engineers can customize castellated pad spacing, board thickness, layer count, and electrical specifications to match different application requirements.
- Simplified production and testing: Castellated modules can be manufactured and tested separately before final integration, helping improve production efficiency and reduce troubleshooting during system assembly.
When designing a castellated PCB, engineers must consider several technical factors, including hole diameter, pad width, copper plating thickness, solder mask clearance, PCB edge tolerance, and assembly process requirements. Incorrect dimensions can result in insufficient solder coverage or reduced mechanical strength.
Highleap PCB Factory provides customized castellated PCB manufacturing solutions based on application requirements, including prototype development and volume production. Our engineering team supports stack-up selection, manufacturing review, and process optimization to help ensure consistent PCB performance.
Applications for Castellated PCBs
Castellated PCBs are widely used in electronic products that require compact size, modular integration, and dependable board-level connections. Typical applications include:
- Wireless Modules: Bluetooth, Wi-Fi, Zigbee, LoRa, and other wireless communication modules commonly use castellated edges because they simplify integration with the main control board. The low-profile connection method supports compact product designs while maintaining reliable RF and power connections.
- Aerospace and Defense Electronics: Aerospace systems often require compact, lightweight, and highly reliable electronic assemblies. Castellated PCB modules can help reduce system size while supporting strict manufacturing and reliability requirements.
- Medical Devices: Portable medical equipment, diagnostic systems, and sensor-based devices require high integration levels. Castellated PCBs allow designers to combine processing, communication, and sensing functions in limited spaces.
- Embedded Systems: Industrial controllers, automation equipment, and smart devices often use modular PCB architectures. Castellated modules simplify integration by allowing pre-tested circuit assemblies to be mounted onto larger control boards.
- Internet of Things (IoT) Devices: IoT products typically require small enclosures, low power consumption, and wireless connectivity. Castellated PCB modules support these requirements by combining multiple functions in a compact package.
- Sensor Applications: Environmental sensors, motion sensors, and monitoring devices benefit from modular PCB designs because individual sensor boards can be replaced or upgraded without redesigning the complete system.
Castellated PCBs are especially valuable when engineers need the advantages of a module approach without increasing the product size through traditional connectors. They provide a balance between manufacturing efficiency, electrical reliability, and mechanical simplicity.
For high-speed or RF applications, castellated PCB performance depends heavily on controlled impedance, material selection, and layout quality. Proper stack-up planning helps maintain signal integrity when high-frequency signals pass through the module connection interface.
Highleap PCB Factory’s Advanced Process for Castellated PCBs
Highleap PCB Factory uses controlled fabrication processes to manufacture castellated PCBs with consistent edge geometry, plating quality, and electrical performance. The manufacturing process includes:
- Advanced PCB stack-up designs: We develop PCB stack-ups based on application requirements, including layer count, dielectric materials, copper thickness, and impedance requirements. Proper stack-up selection supports reliable performance in high-speed, RF, and compact electronic designs.
- Precision drilling and edge processing: Castellated holes require accurate drilling, plating, and routing processes. Manufacturing tolerances must be controlled to ensure consistent half-hole geometry and reliable solder connections during assembly.
- High-quality copper plating: Reliable castellated connections depend on continuous copper coverage inside plated holes and along the exposed edge. Controlled plating processes improve solderability and connection durability.
- Impedance control: High-speed and RF castellated PCB designs require accurate impedance management to prevent signal degradation. Engineers can use our Impedance Calculator to support transmission line calculations and PCB design verification.
- Design verification and inspection: Manufacturing data is reviewed before production begins. Our Gerber Viewer helps engineers verify PCB design files, layer information, and fabrication details before manufacturing.
- Electrical testing and quality assurance: Each production stage includes inspection and testing procedures to verify PCB reliability, including open and short testing, dimensional inspection, and manufacturing quality checks.
The castellated PCB manufacturing process requires close coordination between PCB design rules and fabrication capabilities. Important design considerations include:
- Minimum hole diameter and edge plating requirements
- Solder mask opening dimensions
- Pad-to-pad spacing
- PCB thickness compatibility with the host board
- Assembly solder profile requirements
- Mechanical stress during installation and operation
By considering these factors during the design stage, engineers can reduce manufacturing risks and improve first-pass production success.
Why Choose Highleap PCB Factory for Castellated PCBs?
Highleap PCB Factory supports castellated PCB projects from engineering review through final production. Our manufacturing services are designed for customers who require reliable PCB quality, flexible production options, and technical support.
Key advantages include:
- Customization: We support customized castellated PCB designs with different layer counts, materials, board thicknesses, pad configurations, and electrical requirements. Our engineers work with customers to optimize designs for manufacturing and assembly.
- Fast Turnaround: Our production capabilities support prototype quantities, pilot runs, and larger manufacturing orders. Efficient production processes help reduce development cycles while maintaining manufacturing consistency.
- High-reliability manufacturing: We manufacture PCBs according to IPC Class 2/3 requirements, supporting applications where long-term reliability and stable electrical performance are required.
- Cost-effective production: Whether developing an initial prototype or preparing for mass production, we provide manufacturing solutions that balance performance requirements, production volume, and overall cost.
- Engineering support: Our team assists with design review, fabrication recommendations, material selection, and manufacturing optimization to help customers avoid common PCB production issues.
Castellated PCBs are an effective solution for modern electronics that require compact dimensions, modular architecture, and reliable board-level connections. From wireless modules and IoT devices to industrial and medical electronics, these designs help engineers achieve higher integration while maintaining manufacturing efficiency.
We offer a full range of PCB products, including high-speed PCBs, high-frequency PCBs, and HDI PCBs, ensuring we meet the specific requirements of every project.