Cavity PCB: Thin Designs, Enhanced Performance

What’s in Cavity PCB?

Cavity PCB is a special type of printed circuit board, which is recessed (milled or etched) in one or more specific areas of the board to form a cavity. It is an advanced PCB technology that forms grooves by locally thinning the PCB thickness. The depth of these grooves usually does not penetrate the entire board thickness, but only goes deep into one or several layers inside. It is like digging a pit on the PCB board. It is mainly used to solve the problem of component height restrictions to achieve thinner product design, as well as to optimize heat dissipation and signal performance. Although the manufacturing process is complex and the cost is high, it solves the core needs of space compression, heat dissipation enhancement, and high-precision installation in high-end industries.

Advantages of Cavity PCB

Save space and fix large-sized components

When components that are much larger than the surrounding components need to be installed on the PCB, direct installation on the surface of the PCB will increase the thickness of the entire assembly. Placing these large components in a pre-designed cavity can reduce the total height of the entire PCB assembly, making the product thinner and more compact. Ultra-thin mobile phones, wearable devices (smart watches, headphones), and notebooks/tablets often use this type of circuit board.

Improve heat dissipation

The cavity can be designed under the chip with high heat generation (such as CPU, GPU, power device). Putting the chip into the cavity or letting the chip base directly contact the bottom of the cavity (usually the metal layer) can provide a more direct heat conduction path to the copper layer or heat dissipation substrate inside the PCB, and even a micro heat sink or heat pipe can be installed at the bottom of the cavity. It is mostly used in some high-power density electronic devices, LED lighting, and power conversion modules.

Improve signal reliability

This cavity design provides a better shielding environment for high-speed signal lines or RF components and reduces interference. Sometimes it is used to bury passive components (such as resistors and capacitors) to make them closer to the chip pins and reduce parasitic effects.

High-precision installation

This is one of the core values of cavity PCB, especially in areas that require micron-level positioning, vibration resistance, or automated assembly, such as optical modules, medical probes, and automotive sensors.

Manufacturing Cavity PCBs is usually more complex and more expensive than standard PCBs. Precise 3D design is required, and needs to consider the cavity position, size, depth, and safe distance from internal circuits and component layout, etc. In the Gerber file, the cavity usually needs to be clearly drawn in shape and size in the Board Outline/Cutout (GKO/GML) layer and the routing (GKO) layer. The cavity depth and position tolerance must be strictly controlled; otherwise, it may damage the internal circuit or cause component installation problems. Standard FR-4 may not be suitable for deep cavities or high reliability requirements, so it is necessary to choose materials with higher milling resistance, higher TG value, or better thermal conductivity.

The production of cavity PCB has high requirements for the factory’s equipment accuracy/process control/material technology, and quality certification system. Jerico Multilayer PCB has relevant professional production capabilities in the following aspects:

Precision machining: CNC+laser composite process, to ensure the width processing capacity ≤2mm. Pulse plating line + horizontal copper deposition depth-to-width ratio ≥10:1, copper thickness uniformity >90%.
Meet various special material requirements: High CTI substrate (CTI≥600V/IEC 60112), High frequency materials (Dk±0.05, Df≤0.002)
Metal insert process:IPC-9701 tensile test ≥300N
Factory qualification: UL 94 V-0&IATF 16949