The electronics industry is increasingly adopting High-Density Interconnect (HDI) PCBs (Printed Circuit Boards). As electronic components become smaller and lighter, circuits are achieving higher performance levels. PCB manufacturers, such as Stream PCB Inc., are responding by integrating more functionality into smaller spaces, offering advanced HDI PCBs to meet these demands.
With semiconductor fabrication processes shrinking device sizes, the reduced physical distances between components enable faster signal rise and fall times. This allows devices to operate at higher frequencies. However, these smaller devices now integrate more functionality onto the chip, which leads to greater heat generation. To counter this, manufacturers reduce supply voltage, which lowers power consumption but also results in signal loss and increased sensitivity to noise.
HDI technology offers a solution, with high-performance laminates and microvia fabrication enhancing the high-frequency performance of the PCB. Microvias in HDI boards significantly reduce parasitics—by a factor of 10—compared to through-hole vias. Microvias also provide lower inductance, and when combined with low-inductance decoupling capacitors and via-in-pad designs, they reduce noise sensitivity, especially in high-speed logic circuits.
The semiconductor industry now offers smaller gate geometries and a higher number of total gates, enabling faster speeds and more functionality. With the adoption of larger wafers, prices continue to decrease. This has led to IC packaging with pitch devices as small as 0.80 and 0.65 mm, requiring HDI technology for PCB design. Blind vias help optimize space on inner layers, reducing via lands and enabling via-in-pad designs.
HDI technologies offer several design advantages that lead to numerous benefits, including:
HDI technologies, such as via-in-pads and blind vias, allow for easier component placement, accelerating the time-to-market. Smaller spacing, boulevard routing, improved BGA breakouts, and simplified auto-routing with blind/buried vias—over through-hole vias—improve design efficiency.
The use of blind vias, as opposed to through-hole vias, improves electrical performance and reduces design time. The reduction in noise and enhanced signal integrity can also minimize the need for multiple design iterations.
Extensive reliability testing has proven that microvias offer superior reliability compared to through-hole vias. The aspect ratio of vias (depth to diameter ratio) can be as high as 20:1 due to the thin materials and low Z-axis TCE materials used in HDI technology.
The IPC-4101B standard covers the variety of HDI materials in use, which exceed the options available for traditional multilayer laminates. Moreover, thin HDI materials are well-suited for efficient thermal heat transfer.
Properly planned and executed HDI PCB design can result in multilayer HDI boards that are less expensive than their through-hole counterparts. For example, designers replaced a 14-layer through-hole multilayer board with an 8-layer HDI board, reducing the number of layers by six. By utilizing both sides of the board and optimizing the layout, designers reduced component area by 40%.
Many modern electronic devices rely on HDI technology, resulting in products that are both smaller and lighter. The use of HDI allows manufacturers to reduce the form factor of equipment while maintaining functionality.
At Stream PCB, we specialize in manufacturing HDI boards with tight tolerances. Even minor layout errors can lead to significant issues, which is why we ensure top-quality boards with significantly higher circuit densities compared to traditional PCBs.
Type 1: Features a single microvia layer on at least one side of the core. Plated microvia technology and PTH (plated-through-hole) create the interconnections. The PCB may contain blind vias but no buried vias.
Type 2: Includes a single microvia layer on at least one side of the core, with both buried and blind vias. Plated microvia technology and PTH establish interconnections.
Type 3: Contains at least two layers of microvias on one or both sides of the core, with both buried and blind vias. Plated microvia technology and PTH create the interconnections.
HDI technology enables the creation of smaller, more efficient PCBs with high-density interconnects, meeting the growing demands of the electronics industry.
The production process for HDI PCBs differs from that of traditional PCBs. At Stream PCB, we address several key design considerations throughout the fabrication process to ensure the highest quality HDI boards:
The lamination process for HDI PCBs involves combining the PCB core (or cores) with copper and prepreg layers (for multilayer PCBs), applying heat and pressure to form the structure. The lamination process may vary for different boards. After the lamination phase, vias are drilled. Unlike regular PCBs, this process can be repeated multiple times in HDI production. Sequential lamination helps prevent shifts or breakages during the drilling process, ensuring greater precision and quality.
The via-in-pad process allows vias to be placed within the flat pads of the PCB. After creating the vias, they are plated, filled with a specific via fill material, capped, and then plated again to cover the vias. The creation of via-in-pads involves 10–12 steps, requiring specialized equipment and highly skilled technicians. Via-in-pads are essential in HDI PCBs as they save space, enhance thermal management, and enable high-density wiring solutions.
At Stream PCB, we use various via fill types tailored to specific applications and requirements. Materials such as silver, copper, conductive epoxy, and non-conductive epoxy are commonly used. Non-conductive epoxy is the most widely used fill type. We offer via fills that are flush with copper and solder, making standard vias and microvias either blind or buried. These vias are drilled and plated to hide beneath the surface-mount technology (SMT) land. We carefully control drill depths through multiple cycles to ensure precision, utilizing specialized equipment for the process.
We offer HDI PCBs in various layouts, with the 1-n-1 and 2-n-2 types being the most common. A 1-n-1 layout is a basic HDI PCB with a single build-up of HDI layers, featuring one sequential lamination on each side of the core. The 2-n-2 layout consists of two HDI layers, where microvias can be stacked or staggered. For more complex designs, we often use stacked copper-filled microvia structures. Although stacked microvias can be built to high levels in X-n-X layouts, these designs are more complex and incur higher costs.
We also manufacture any-layer HDI, an extremely dense layout where conductors are freely interconnected across any layer of the PCB with laser-drilled microvias. This type of design is typically used in mobile and smartphone CPU and GPU chips.
For complex any-layer HDI designs, laser-drilled microvias are essential. These lasers can drill holes as small as 20 microns in diameter, cutting through glass and metal with precision. Although they create tiny holes, the results are clean, with no burrs or debris, ensuring high-quality microvias for the HDI board.
As a leading HDI PCB manufacturer, Stream PCB utilizes state-of-the-art technology to produce fine lines on HDI boards. We operate in controlled environments with clean rooms to ensure secure processing and precise results. Since repairs are not feasible for such fine details, our focus is on getting it right the first time. We primarily use contact imaging and Laser Direct Imaging (LDI) for applications that require extreme precision. LDI, in particular, is well-suited for handling fine lines and small spaces, enabling us to continuously expand our capabilities to accommodate even the smallest form factors.
At Stream PCB, we have been providing High-Density Interconnect (HDI) printed circuit boards for over two decades. No tolerance is too tight, and no order is too small for us. We offer a competitive edge with our fast response times, affordable pricing, domestic manufacturing, and unmatched flexibility, ensuring the highest quality and reliability in every project.
If your design reaches a certain level of complexity, switching to HDI technology, which includes blind, buried, and microvias, will likely result in improved yield and reduced costs.
HDI boards use thinner laminations, traces, spaces, and smaller vias, maximizing the available real estate on the board. This allows for higher component density and reduces the number of layers required, which ultimately lowers the overall PCB cost.
Selecting the right materials for HDI board manufacturing is crucial. Materials must meet both temperature and electrical requirements, while also ensuring high-speed performance to maintain signal integrity.
The via structure is based on the specific needs of the application, such as whether the microvias will be stacked or staggered. A key factor to consider in design is the microvia aspect ratio.
No, there is no direct relationship between the substrate material and whether microvias are stacked or staggered.
At Stream PCB, we prioritize precision and quality in every aspect of HDI PCB manufacturing, ensuring that your designs meet the highest standards.
© All Copyright 2025 by streampcb.com
