In today's world where electronic devices relentlessly pursue peak performance and miniaturization, a technology called “Ultra High Density Interconnect” is emerging as the driving force behind this transformation. It goes beyond simply making circuit board traces finer and vias smaller—it represents a profound engineering revolution that enables cutting-edge innovations ranging from AI supercomputers to ultra-slim smartphones. The following content will take you deep into the core principles of UHDI, its technological drivers, and how it is redefining the limits of modern electronics manufacturing.
In this article:
Part 1. What is Ultra-high Density Interconnect Part 2. Key Technical Features Part 3. Why UHDI is Needed Part 4. Differences Between UHDI and Traditional HDIWhat is Ultra-high Density Interconnect
This is a crucial concept in electronic engineering and semiconductor technology, particularly in the manufacturing of high-end printed circuit boards (PCBs). We can understand it both literally and in its deeper meaning. Ultra-High Density Interconnect refers to a PCB technology that supports highly complex and miniaturized electronic devices by achieving the maximum number of electrical connections (i.e., “interconnections”) within an extremely small space.
Simply put, it involves packing as many ultra-fine traces and vias as possible onto the smallest possible area, effectively “weaving” components like chips together in a dense configuration.
Key Technical Features
Finer line width/line spacing:- The line width/line spacing of traditional PCBs may exceed 50 µm (micrometers)
- UHDI typically refers to line width/line spacing less than 30µm, with advanced technologies achieving even <15µm or finer. This is significantly thinner than a human hair (approximately 70-100µm)
- Using microvia or any-layer interconnect technology
- Via diameters can be as small as 25µm or even smaller. In contrast, the limit for traditional mechanical drilling is approximately 150µm
- Microvias can be used to connect any two layers of a PCB directly, eliminating the need to drill from the top layer to the bottom layer. This significantly enhances routing flexibility and density
- To support such intricate structures, high-performance substrate materials such as modified epoxy resins, polyimides, or liquid crystal polymers are required, as these materials offer superior dimensional stability and electrical properties
Why UHDI is Needed
To meet the most demanding requirements for chip performanceModern high-performance computing chips and artificial intelligence accelerators feature thousands of input/output pins and generate massive data flows. UHDI provides an ample number of highly refined electrical channels, ensuring massive data can be transmitted between chips at high speeds with minimal loss, thereby preventing performance bottlenecks.
To achieve miniaturization and lightweight design in electronic devices
In consumer electronics such as smartphones and wearable devices, internal space is extremely valuable. UHDI technology compresses complex circuit networks onto minimal board area, freeing up space for larger batteries or additional sensors. This makes it crucial for achieving both slim profiles and powerful functionality in devices.
To ensure signal integrity and system stability
As signal rates enter the high-frequency era, traditional cabling becomes susceptible to interference and loss. UHDI's fine lines and microvias effectively reduce signal crosstalk, attenuation, and delay, delivering superior electrical performance. This is critical for high-speed digital circuits and RF systems, forming the foundation for ensuring stable and reliable operation throughout the entire system.
To support the innovation and application of cutting-edge technologies
From autonomous vehicle sensing and computing to advanced medical implants and next-generation communication technologies, these cutting-edge fields demand electronic systems to achieve ultra-high integration and reliability under severe physical constraints. UHDI serves as the core enabling technology for miniaturizing and delivering high performance in these complex systems.
Differences Between UHDI and Traditional HDI
If traditional HDI technology is akin to constructing four-lane and six-lane arterial roads in a city, then UHDI represents the planning and construction of a super transportation network featuring countless micro-streets, elevated interchanges, and underground tunnels within the same footprint. The core distinction between the two lies not in their fundamental nature, but in the leap in precision and complexity they achieve.
Traditional HDI has achieved preliminary circuit densification through microvias and finer traces, playing a pivotal role in enabling the slim profiles of devices like smartphones. UHDI, however, pushes this precision to its ultimate limit, achieving orders-of-magnitude improvements in trace width, via size, and interlayer interconnect freedom. This advancement transcends mere “thinner and smaller”—it delivers a qualitative leap. It enables direct, arbitrary connections between all circuit layers within minuscule spaces, liberating circuitry from the spatial constraints of conventional routing.
Therefore, UHDI is not merely an enhanced version of HDI; it is a foundational technology capable of supporting next-generation electronics. It serves scenarios demanding extreme data processing speeds, system integration, and physical miniaturization—such as high-performance servers and AI chips handling massive computational tasks. Indeed, UHDI is the unsung hero transforming these cutting-edge technologies from blueprints into reality.
In summary, ultra-high-density interconnect is far more than a simple manufacturing upgrade; it represents a fundamental leap forward in electronic integration technology. By revolutionizing the microscopic scale, it builds a high-speed, reliable data bridge between chips and systems, thereby opening new frontiers of possibility for the entire electronics industry. In a sense, UHDI is precisely the key to continuously unlocking the infinite potential of the digital world within the constraints of physical space.
One-Stop HDI PCB Manufacturer and Its PCB Via Filing Capabilities
If you're looking for turnkey HDI electronics manufacturing services (EMS) from hardware development to PCBA fabrication and box-build assembly, you can work with the one-stop HDI PCBA manufacturer PCBONLINE.
Founded in 1999, PCBONLINE has R&D capabilities for HDI projects and EMS manufacturing capabilities, including via filling for stacked vias. It provides 4-to-64-layer HDI PCB fabrication, assembly, and PCBA box-build assembly. You can order various HDI PCBs from PCBONLINE, such as FR4, polyimide (flexible PCB), polyimide + FR4 (rigid-flex PCB), and PTFE/Rogers (high-frequency PCB).
3000m² of production capacity per day for HDI PCBs with builds of 1+N+1, 2+N+2, 3+N+3,4+N+4, and arbitrary interconnection in any layers.
PCBONLINE has hardware and software R&D capabilities for IoT applications requiring HDI design, including PCBA and enclosures.
We can manufacture complex PCBs with stacker vias, via-in-pad, microvias, inlay boards, heavy copper designs, and hybrid and fine structure lay-ups.
Besides HDI PCB fabrication, we have powerful capabilities in fine-pitch assembly for HDI PCB assembly.
We have rich R&D and manufacturing experience for HDI applications such as FPGA boards.
High-quality HDI PCB and PCBA manufacturing certified with ISO 9001:2015, IATF 16949, RoHS, REACH, UL, and IPC-A-610 Class 2/3.
Here'e the PCB via filing capabilities at PCBONLINEL:
- Micriavia filling with copper: laser via size 0.1-0.125mm, priority 0.1mm
- Finished hole size for via-in-pad filling with resin: 0.1-0.9mm (drill size 0.15-1.0mm), 0.3-0.55mm normal (drill size 0.4-0.65mm)
- Max aspect ratio for via-in-pad filling with resin PCB - 12: 1
- Min resin plugged PCB thickness: 0.2mm
- Max via-filling ith resin PCB thickness: 3.2mm
- Making different hole sizes with via filling in one board: Yes
- Via filling with copper/silver: Yes
If you need HDI PCBAs or any other PCBAs requiring via filling, please send your email to PCBONLINE at info@pcbonline.com. We will provide one-on-one engineering support to you.
Conclusion
Via filling is used for creating stacked vias in HDI PCB fabrication, BGA/CSP/QFN IC packaging, and filling PCB via-in-pad with resin during multilayer PCB fabrication. If you need one-stop electronics manufacturing for your HDI PCBA project, contact the one-stop advanced PCB manufacturer PCBONLINE for high-quality PCBA and box-build solutions tailored to your project's needs.
PCB fabrication at PCBONLINE.pdf
