Background Theory > PCB Design > High Density Interconnect (HDI) PCBs

"2+N+2 HDI" is another type of High Density Interconnect (HDI) printed circuit board (PCB) design that builds upon the principles of HDI technology. Just like the previously discussed "1+N+1 HDI," the "2+N+2 HDI" designation describes the layer configuration of the PCB.

In a 2+N+2 HDI PCB:

2: This represents two core layers, one at the top and one at the bottom. These core layers provide structural support and can also contain traces, pads, or components.

N: Similar to the previous explanation, the "N" layers represent the number of build-up layers placed between the two core layers. The build-up layers are where most of the interconnections, traces, and components are located. The specific number of build-up layers can vary based on design requirements.

2: These two additional core layers are placed on the outermost sides of the PCB, providing further structural integrity and additional space for traces, pads, or components.

Advantages of 2+N+2 HDI PCBs include:

•Higher Component Density: The build-up layers allow for increased component placement and interconnectivity, enabling more features and functionality in a smaller space.

•Improved Signal Integrity: The use of microvias and advanced routing techniques in HDI designs contributes to better signal integrity and reduced signal propagation delay.

•Enhanced Thermal Performance: Microvias can be used to facilitate heat dissipation, helping manage thermal characteristics of the PCB.

•Reduced Size and Weight: The compact design of 2+N+2 HDI PCBs contributes to the overall reduction in the size and weight of electronic devices.

•Design Flexibility: The combination of core and build-up layers, along with microvias, allows for flexible and efficient routing, making it possible to accommodate complex circuit designs.

2+N+2 HDI PCBs are commonly used in a variety of applications that demand compactness, high performance, and efficient interconnectivity. These may include smart phones, tablets, laptops, wearables, medical devices, aerospace electronics, and more. The choice between different HDI configurations, such as 1+N+1, 2+N+2, or other variations, depends on the specific design requirements, the desired level of miniaturization, and the performance objectives of the electronic product.