PCB Types Explained
An overview of the main PCB construction types Exception PCB manufactures, from single-sided and multilayer through to HDI, RF, flex and rigid-flex, with guidance on which construction suits different design requirements and applications.
Printed circuit boards come in a range of constructions, each suited to different design requirements, space constraints and performance demands. Getting this decision right at the design stage affects manufacturability, cost and long-term reliability just as much as component placement or routing does.
This guide sets out the main PCB types Exception PCB manufactures, from simple single-sided boards through to RF, HDI and rigid-flex constructions, and explains which application each one suits.
SINGLE-SIDED PCBS
A single-sided PCB carries one conductive copper layer on one side of the substrate. Tracks, pads and components all sit on the same face, making it the simplest and most cost-effective PCB construction available.
Single-sided boards suit straightforward, low-density circuits where routing complexity is limited, and remain a practical choice for high-volume, cost-sensitive applications.
DOUBLE-SIDED PCBS
A double-sided PCB has copper layers on both sides of the substrate, connected by plated through-holes known as vias. This doubles the available routing area compared with a single-sided board, supporting higher component density and more complex circuits.
Double-sided construction gives designers more routing flexibility without the cost or complexity of a multilayer build, and it remains widely used across industrial, consumer and commercial electronics.
MULTILAYER PCBS
Multilayer PCBs add internal copper layers within the board stack, separated by insulating prepreg. These extra layers let complex circuits route across dedicated signal, power and ground planes, improving electrical performance, reducing noise and enabling far higher component densities than a double-sided board allows.
Exception PCB manufactures multilayer boards from two layers up to 32 layers as standard, with advanced builds available for more demanding designs. Multilayer construction is used extensively across aerospace, defence, medical, telecoms and industrial applications, where circuit complexity and signal integrity are critical.
RIGID PCBS
A rigid PCB is built on a solid, non-flexible substrate, most commonly FR4, that holds its shape throughout manufacture, assembly and service. Rigid construction is the baseline from which flex, rigid-flex and HDI boards are derived, and remains the right choice for the majority of PCB applications.
HDI PCBS
High Density Interconnect (HDI) PCBs use laser-drilled microvias, blind vias and buried vias to achieve a higher connection density than conventional mechanical drilling allows. This supports smaller pads, finer lines and more connections within a given board area, making HDI construction well suited to compact, high-performance designs.
HDI is commonly specified for designs using fine-pitch BGA components, where pad size and routing density requirements cannot be met with standard through-hole via technology.
Exception PCB's HDI capability includes laser microvias down to 75 µm, sequential lamination up to six cycles, and layer counts up to 32. Read more about our HDI PCB manufacturing capability.
RF PCBS
RF and microwave PCBs carry the signals behind wireless products, from handheld medical and industrial devices through to base stations, radar and satellite systems. Performance depends on tightly controlled dielectric properties, copper profile and impedance, so RF boards demand a level of process control beyond conventional multilayer fabrication.
Exception PCB manufactures RF PCBs using controlled material systems including PTFE, Rogers and low-loss FR4 variants, supporting controlled impedance to ±5% on advanced builds. Read more about our RF PCB manufacturing capability.
FLEX PCBS
A flex PCB uses a flexible polyimide substrate instead of a rigid laminate, allowing the board to bend, fold or flex during installation or in service. Flex circuits can replace conventional wiring harnesses entirely in applications where space, weight or dynamic movement rule out a rigid board.
Flex PCBs are used across medical devices, aerospace systems, cameras and wearables. Exception PCB has a dedicated flex manufacturing team with CAM engineering support for flex and rigid-flex designs. Read more about our flex capability.
RIGID-FLEX PCB
A rigid-flex PCB combines rigid and flexible sections within a single, integrated construction. Rigid sections carry components and connectors in fixed positions, while flexible sections provide the interconnections between them, replacing separate boards and cable assemblies.
This reduces the number of connectors and solder joints in an assembly, which improves reliability and cuts the risk of connection failure. It also allows the assembly to fold into a three-dimensional shape, saving space and simplifying installation.
Exception PCB manufactures rigid-flex boards up to 24 layers, with panel sizes up to 406 × 559 mm. Rigid-flex is used in demanding applications including aerospace platforms, defence systems and implantable medical devices, and requires careful DFM review at the design stage. Read more about our rigid-flex capability, or explore our Design for Manufacture service.
WHICH PCB CONSTRUCTION SUITS YOUR PROJECT?
Choosing between constructions comes down to how the finished product needs to perform, not just its immediate cost. The table below sets out where each one typically fits.
| PCB TYPE | BEST SUITED TO |
|---|---|
| Single-sided | Simple, low-cost, low-density circuits |
| Double-sided | General industrial, consumer and commercial electronics |
| Multilayer | Complex routing, signal integrity, aerospace, defence, medical |
| Rigid | Baseline construction for most standard applications |
| HDI | Fine-pitch BGA, compact high-performance designs |
| RF | High-frequency, radar, communications, aerospace |
| Flex | Dynamic movement, weight and space-constrained assemblies |
| Rigid-flex | 3D packaging, reduced connectors, aerospace, medical, defence |
If you are weighing up two or more of these constructions for the same design, our engineers can review your requirements and recommend the right build before you commit to layout. Talk to our engineers.
ENGINEERING SUPPORT ACROSS EVERY PCB TYPE
Every PCB type in this guide is manufactured at our facility in Tewkesbury, supported by an in-house engineering team who understand how these boards behave in production, not just on the datasheet. That combination of technical depth and hands-on manufacturing experience is what lets us take a design from prototype through to volume production with confidence, whichever construction it needs.
To discuss your requirements, get in touch with our team.
PCB TYPES FAQS
Both use several layers of copper, but HDI boards add laser-drilled microvias, blind vias and buried vias to achieve much finer routing density. A conventional multilayer board typically relies on mechanically drilled through-holes, whereas HDI construction supports smaller pads and finer lines, making it better suited to fine-pitch BGA components and compact, high-performance designs.
Choose flex when the whole assembly needs to move or fold, such as in a camera module or wearable device.
Choose rigid-flex when only part of the design needs to move or fold, while components and connectors stay fixed on rigid sections. Rigid-flex also removes the connectors and cables that a separate flex and rigid board would otherwise need.
Find out more about Exception PCB's flex and rigid-flex capability.
Exception PCB manufactures multilayer boards from two layers up to 32 layers as standard, with advanced builds available for designs that need to go further. Layer count is driven by routing density, signal integrity requirements and the space available on the board.
Yes. RF and microwave designs need materials with stable, predictable dielectric properties, such as PTFE, Rogers laminates or low-loss FR4 variants, to keep signal loss and impedance under control at high frequencies. Standard FR4 can introduce too much variation for RF performance to stay within tolerance.
As early as possible. Construction choice affects layer count, material selection, via strategy and cost, all of which are far easier to adjust before layout is finalised than after. Our engineers can review your requirements at concept stage and recommend the right construction before you commit to a design.