PCB Design, PCB Manufacturing

HDI PCB: A Guide to HDI PCB Design and Manufacturing

HDI PCB Stackup

Technological developments continue to fundamentally impact key factors in the electronics industry in general, making it important for manufacturers to keep up with everything new in this field. High Density Interconnect (HDI) is one such technology that has brought profound development in Printed Circuit Boards (PCB) industries. So, what is HDI?

What is HDI?

HDI is short for High Density Interconnect, it is one of the most important types of printed circuit boards, which is characterized by smaller areas and more wires, unlike regular PCB boards. It contains microvias technology, which are small holes similar to small holes in the PCB to pass communications between layers. These holes are made through the laser drilling process, which makes microvias replace traditional holes. This helps in communication between many layers in a very small area and also has buried vias and blind vias, allowing for higher board density. HDI PCBs are very important in the manufacturing of modern electronic devices. Its high capabilities for complete control in small spaces and high density make it ideal for all electronic device applications that depend on its small size, lightweight, and efficient performance.

The Advantages of HDI PCBs

HDI PCBs have many advantages that have made them widely used in the modern electronics industry. It is a technology that supports miniaturization, which has become one of the fundamental features of all electronic developments.

HDI PCBs also improve electrical performance by shortening the paths that carry electrical signals, thus faster transmission of signals and reducing the risk of these signals being lost or intercepted. So a lot of functions can be combined in one small HDI circuit board, with high-speed signal transmission and reliable connections.

One of its most important features is that it provides a smaller size and less weight. As circuit density increases, we find that they require fewer layers and fewer materials, which contributes to making them lighter and thinner, making them ideal for portable and wearable devices.
When compared to traditional PCBs, HDI PCBs offer superior capabilities and design flexibility by adding components in both outer layers. It can also accommodate very high bond densities while maintaining structural integrity. Hence this technology has given us greater freedom in design and innovation, unlike traditional PCBs which are limited to layers and orientation density.

Finally, by incorporating microvias and other HDI features into its configuration, it makes it easier to place a greater number of components over distances Very short, which contributes to reducing transmission time and saving energy. It also enhances on-board communications, making it more reliable and better for difficult and complex applications, it makes them more effective in the long run.

HDI PCB with Blind and Buried Vias

A Comprehensive Guide to HDI PCB Design and Manufacturing

Simply put, the design idea of HDI PCBs revolves around the necessity of accommodating high-density circuits in limited spaces, without compromising performance and reliability. The process of designing and manufacturing HDI PCBs is different from simply manufacturing traditional PCBs, but it is very important. We find that the manufacturing processes depend on the design requirements and ensure their efficiency. Please refer to the following guide to HDI printed circuit board design and manufacturing.

Also read: RF PCB Design: A Practical Guide for Engineers

Essential Points in HDI PCB Design:

Since the design process of HDI PCBs is a process that the manufacturing phase depends on in all its aspects, tracking design requirements with high accuracy allows manufacturers to simplify manufacturing processes and avoid errors that may lead to remanufacturing, thus ensuring the successful implementation of the manufacturing phases.

  • In the design process, the width and spacing of the elements must be taken into account, to maintain signal integrity and ensure no interference in narrow bands.
  • To ensure reliable communication, the complexities of connections between high-density layers containing a large number of elements must be taken into account, thus accommodating dense circuits within a limited space.
  • Appropriate materials that are compatible with the design must be chosen, such as copper foil and other materials that directly affect the quality and effectiveness of the final product.
  • Methods of regulating and dissipating heat, especially in designs that contain a large number of components to perform their functions. It is necessary to trace the thermal paths and place the components appropriately to distribute the heat evenly.
  • Finally, it is necessary to follow up on the details of integrating the microchannels, which are considered one of the most important components of the HDI PCB system, and they act as channels that carry signals between the different layers. They reduce the interference between signals significantly, thus obtaining high reliability and effectiveness of the electronic devices produced.


Essential Points in HDI PCB Manufacturing:

Ensure that design requirements are followed and optimized, ensuring manufacturing efficiency and effectiveness. Below is an explanation of what the manufacturing process involves.

  • Microvias are created through laser drilling techniques, which provide high precision. This technology also allows the development of complex, high-density circuits while ensuring signal quality integrity and electrical performance.
  • After the drilling process, copper is coated on the walls of the holes to ensure electrical connections between the layers.
    The layers are pressed together through heat and pressure to form a single multi-layer structure.
  • Surface finishes involve choosing one of the most common finishing techniques, Hot Air Solder Leveling (HASL), Organic Solderability Preservative (OSP), and Electroless Nickel Immersion Gold (ENIG). This depends on the application requirements.
  • Quality tests include electrical tests, impedance tests, and signal analysis tests.
  • Visual inspection is performed using Automated Optical Inspection (AOI) and X-ray inspection to detect defects such as holes deficiencies or differences between layers.

By integrating design and manufacturing processes, manufacturers can create a robust and efficient framework to maintain quality and smooth operation throughout all stages of production. The manufacturing process of HDI PCBs aims to produce exceptional, reliable, high-quality, and efficient electronic devices that meet consumer requirements and industry standards.

Also read: What is Thick Copper PCB and its Applications?


HDI represents a major development in the fields of HDI printed circuit board design and manufacturing, and this importance is evident with all the advantages that HDI technology offered at the beginning of the article, from small size, lightweight, high density, and durability. This makes it one of the essential components in an electronics design, whether it is consumer electronics or even cutting-edge devices such as advanced driver assistance systems (ADAS), aerospace, and defense, and other systems and applications that require strong design capabilities and improved electrical performance. HDI technology has simplified and improved the integration and serialization of complex PCB circuits in small, tight spaces.

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