High-density interconnect, heavy‑copper, and flexible/rigid‑flex PCBs represent the cutting edge of circuit board design. At Hi5 Electronics, we specialise in these advanced technologies, offering end-to-end design, prototyping and manufacturing to meet demanding requirements. This article explores each technology’s features and benefits, illustrating when and why to use them.
HDI PCBs use tiny laser-drilled microvias and blind/buried vias to pack far more circuits into a given area. By connecting layers without large through-holes, HDI boards achieve much denser routing and smaller form factors. For example, modern smartphones often use 8–12 layer HDI boards under 1 mm thick. This miniaturisation is critical in 5G handsets, IoT devices and even medical implants where space is extremely limited. HDI also improves performance: shorter interconnects boost signal integrity and support high-speed data rates (essential for 5G). Typical advantages of HDI include:
Ultra-compact layouts: Microvias (~0.1–0.15 mm) and fine traces free up board real estate, enabling thinner, lighter boards without sacrificing functionality.
High component density: More routing layers and via channels mean hundreds of I/Os on a small board (e.g. 1000+ components on a credit-card PCB).
Enhanced signal speed: Shorter, controlled-impedance traces reduce signal loss, supporting GHz frequencies and 5G speeds.
Reliability: HDI boards withstand vibration and thermal cycling better, improving durability in rugged use.
HDI is widely used in mobile and high-tech markets. Apart from phones, HDI’s compactness is key for wearable electronics, medical devices and aerospace avionics. By using cutting-edge laminates and precision drilling, Hi5 Electronics can manufacture HDI boards that meet the tight tolerances these applications demand.
Advanced products often need more than just four layers and standard copper. UK manufacturers like Hi5 invest in complex stack-ups and specialty materials. As noted by a UK industry expert, simply making 2–4 layer boards “isn’t sustainable” domestically. Instead, we build high-layer-count boards and heavy-copper designs for power-hungry applications. Multi-layer PCBs (up to 32+ layers) allow segregating signals, power and ground planes for optimal performance. Heavy-copper PCBs use thick copper (4–20 oz) to carry very high currents with minimal voltage drop. These boards are essential in power electronics – for example, electric vehicles, motor drives and renewable-energy inverters – because they handle large currents and dissipate heat effectively. Key points include:
Complex stack-ups: More layers let designers route dense signals and incorporate power/ground planes. Hi5’s facilities handle 8–24 layer boards with fine tolerances.
High-current handling: Heavy-copper PCBs (copper >3 oz) carry far more current and improve thermal stability. They’re used in automotive power supplies, industrial equipment and renewable energy systems that demand reliability under intense conditions.
Expertise: Creating these boards requires precise plating and etching. At Hi5 Electronics we have the equipment and know-how to produce heavy copper up to 10–20 oz per layer as well as quick-turn multi-layer prototypes.
By focusing on these specialties, Hi5 can serve customers who need advanced power and multi-layer boards that typical vendors cannot supply.
Flexible PCBs (flex) and rigid-flex boards offer unique packaging advantages. Flex PCBs use thin polyimide substrates, making them lightweight and bendable. They can curve or fold into three-dimensional shapes, fitting where rigid boards cannot. This flexibility often eliminates bulky wiring: a single flex assembly can replace multiple boards and connectors. Rigid-flex PCBs integrate flex layers with rigid sections, combining high component density with built-in flex routes. This is ideal for aerospace, medical or military electronics, where space is tight and reliability is crucial. Key benefits include:
Weight & space savings: Flex circuits are very thin and light. They conform to enclosures, freeing up internal space.
Connector elimination: Flex/rigid-flex boards can span multiple rigid sections without external cables, removing connectors and reducing assembly labor.
Durability: Rigid-flex designs handle vibration and thermal stress well. By integrating flex into the board, they avoid failure points of wired harnesses, improving overall reliability.
Faster assembly: With fewer separate PCBs and interconnects, assembly is faster and product size shrinks.
Hi5 Electronics produces both flex and rigid-flex assemblies to support compact, high-reliability designs. Our team works with customers to design the optimal layout (bend radii, layer stack, etc.) for their application, whether it’s a space-constrained aerospace module or a wearable medical sensor.
The rise of 5G and other high-speed systems places new demands on PCB design. High-frequency signals (millimeter-wave 5G, Wi-Fi6, etc.) require specialized materials (low-loss laminates, high-Tg substrates) and precise layer stackups to maintain signal integrity. Designs must control impedance and minimize crosstalk at GHz rates. Crucially, higher data rates also mean more switching power and heat. Exceptional thermal management becomes mandatory. We incorporate thermal vias, copper pours, and heatsink layers to spread heat away from hot components. As an RS DesignSpark industry overview notes, “5G … requires specialized PCBs and new innovations… increased performance also translates to greater heat generation, so exceptional thermal management is necessary”. In practice:
Advanced materials: We source high-frequency laminates (e.g. Rogers, polyimide, PTFE) to reduce loss and dispersion at GHz frequencies.
Controlled impedance: Tight fabrication tolerances ensure consistent trace width/spacing and layer dielectric to meet 50Ω (or other) impedance targets.
Thermal solutions: Strategic use of thermal vias, metal cores or heatsinks prevents overheating in densely packed boards.
By leveraging these techniques, Hi5 helps engineers deliver 5G-ready and high-speed products that stay cool and reliable under demanding conditions.
Engineers working on next-generation electronics have many PCB options: from ultra-HD‑I interconnects to heavy-current power boards, and flexible circuits that reshape how products are packaged. By explaining these technologies and their applications, we highlight how Hi5 Electronics’ manufacturing expertise can support cutting-edge designs. Our in-house team and facilities are equipped to design and build high-density HDI PCBs, multi-layer and heavy-copper boards, and both flex and rigid-flex assemblies.
We stay up-to-date with industry trends—citing analyses from DesignSpark and others—to ensure your project uses the right PCB solutions.
Contact Hi5 Electronics to explore how our advanced PCB technologies can bring your product vision to life.
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