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Types of Printed Circuit Board

A complete guide to PCB Types
Table of Contents

A printed circuit board (PCB) is the core component of modern electronic devices that forms the platform for mounting and connecting electronic components using conductive pathways and traces etched from copper sheets laminated onto a non-conductive substrate. PCB plays a vital role in electronic products and has become an indispensable part of our daily lives.

PCB can be classified in multiple ways based on different categorization methods like its structure, construction method, and material characteristics. ELEPCB, as an innovative PCB manufacturer, provides various PCB types and strives to offer customized PCB solutions to satisfy all kinds of technical and industrial needs.

An Introduction to PCB Types

PCB is a broad concept that encompasses many variants optimized for diverse application scenarios. PCB types can be classified based on different standards to facilitate discussion and selection. The most common classification methods include structure-based, construction-based, and characteristic-based categorizations.

Structured-Based PCB

Structured-based classification refers to PCB types delineated by the number of copper layers in their laminate structure.

Single-Sided PCB

Single-Sided PCBs are the simplest and most basic type of PCB. They consist of a single layer of substrate material, typically made of fiberglass-reinforced epoxy. They have conductive traces and components mounted on only one side of the board. The other side typically has a protective solder mask layer. These PCBs are commonly used in simple applications where the circuitry is uncomplicated and cost-effectiveness is important. For example, a single-sided PCB may be used in a basic calculator, a garage door opener, or a simple LED lighting circuit.

single-sided-layer-PCB-board

Double-Sided PCB

Double-sided PCBs have conductive traces and components mounted on both sides of the board, interconnected using plated through holes or vias. A via is a conductive hole that allows electrical connections between different layers of a PCB. These small openings are strategically placed in the PCB to facilitate the flow of electrical signals and provide a pathway for components and traces to connect vertically.

Double-sided PCBs provide more routing options and can accommodate moderately complex circuits with higher component density. They are widely used in various industries and applications. For instance, they can be found in automotive systems, such as engine control units (ECUs), audio systems, or dashboard controls. They are also commonly used in consumer electronics like televisions, printers, and audio amplifiers.

double-sided pcb board
Double Layer PCB

Multilayer PCB

Multilayer PCBs consist of three or more conductive layers separated by insulating dielectric layers, interconnected using vias. They offer improved signal integrity, reduced electromagnetic interference, and greater design flexibility. Multilayer PCBs are extensively used in advanced electronic devices and high-density applications. For example, they are commonly found in smartphones, tablets, and laptops due to their compact size and the need to accommodate numerous components, high-speed data transmission, and power distribution. They are also used in telecommunications equipment, aerospace systems, and medical devices.

Multilayer PCB Circuit Board Structure

Here is a table sheet about single-sided PCBs, double-sided PCBs, and multi-layer PCBs, presenting a comparison of their key characteristics:

 
Single-sided PCB
Double-sided PCB
Multilayer PCB
Description
PCB with conductive traces on one side of the substrate
PCB with conductive traces on both sides of the substrate
PCB with multiple layers of conductive traces separated by insulating layers
Layer(s)
Single layer
Two layers (Top and Bottem)
Three or more layers
Conductive Traces
On one side
On both sides
On both sides and internally within layers
Component Mounting
Components mounted on one side only
Components mounted on both sides
Components mounted on both sides and internally within layers
Via
No vias
Through-hole vias and/or blind vias
Through-hole vias, blind/buried vias, and more
Complexity
Simple designs
Moderate complexity
High complexity and density
Cost
Lower cost
Moderate cost
Higher cost
Applications
Basic electronic circuits
Wider range of applications
Advanced electronics, high-density PCBs
Example Uses
LED lighting boards, toys
Industrial control boards, automotive electronics, consumer electronics
Smartphones, computers, medical devices, aerospace systems, and more

Construction-Based PCB

Construction-Based PCBs are classified based on the construction materials used in their PCB manufacturing.

Rigid PCB

These are the most common type of PCBs and have a solid, inflexible structure. As the name suggests, rigid boards are non-flexible printed circuit boards constructed from a rigid fiberglass-epoxy laminate substrate, most commonly known as FR-4. Due to their low cost, widespread availability, and simplicity of assembly – rigid PCBs are widely used in applications where rigidity and durability are crucial, such as consumer electronics, automotive systems, and industrial equipment.

FR-4 is composed of woven fiberglass cloth with an epoxy resin binder that solidifies into a rigid and durable sheet. This substrate material provides the PCB with excellent mechanical strength and stability for surface mount component assembly. It is also flame retardant and has good electrical insulation properties.
Rigid PCBs provide designers with tight tolerances for component placement and trace routing due to their rigid and non-flexing substrate. Multiple conductive copper layers can be added to increase circuit complexity and routing density. Overall, FR-4 rigid boards remain the most versatile and economical choice for applications that do not require flexibility.

A sample product of rigid pcb board from elepcb

Flexible PCB

While rigid PCBs are ideal for applications requiring high routing density on a flat, inflexible substrate – some product designs would benefit greatly from a circuit board that can flex and conform to non-planar shapes. This is where flexible PCBs come in.

Flexible circuit boards are constructed using a flexible polymer substrate rather than rigid FR-4. The most common flexible substrate material is polyimide film, which provides the critical characteristics of bending, folding, and twisting without damage.

Some key capabilities of flexible PCBs include:
Conformability: Ability to wrap around complex 3D geometries like tubes, spheres, uneven surfaces that rigid boards cannot achieve.
Compact Size: Can be tightly folded up to reduce the physical footprint in devices like wearables and medical implants.
Built-in Connectors: Flex sections eliminate need for bulky plug-in connectors by acting as a flexible interconnect section between two rigid boards.
Durability: Polyimide substrates are resistant to moisture, chemicals, and temperature fluctuations more than typical FR-4.

a product of flexible pcb from elepcb
flexible-pcb: ben

Flex PCBs are ideal for applications that require compactness, lightweight design, or the ability to withstand vibrations or movements. Areas where flexible circuits excel include medical devices, wearables, consumer electronics, automotive, aerospace and military applications. Some examples include flexible displays, sensor patches, cable harnesses, conformal antenna arrays and more.

Rigid-Flex PCB

There are certain designs that require both the routing density benefits of rigid sections along with the flexibility and compact size achieved through flex sections. This is where rigid-flex PCBs come into play as a hybrid solution.

Rigid-flex boards incorporate discrete rigid and flexible sections onto the same multilayer circuit board substrate. The rigid sections provide placement for dense surface mount components and routing similar to a standard rigid board. Meanwhile, the flexible polyimide sections allow tight bends and folds to connect the various rigid areas conformally.

rigid-flex-pcb

This allows the board to fold into complex shapes while keeping components and critical traces on rigid spans for increased reliability compared to fully flexible boards. Rigid-flex technology also eliminates the need for bulky plug-in connectors found on multi-board designs.

Some common applications of rigid-flex boards include medical devices, wearables, virtual/augmented reality headsets, displays, and more. By combining the benefits of rigid and flex technologies, designers gain maximum flexibility to lay out circuits creatively within size, shape and connectivity constraints.

Characteristic-Based PCB

Characteristic-Based PCBs are classified based on specific characteristics that cater to specialized applications.

Metal-Core PCB

For applications involving high power electronics generation, modern systems are pushing boundaries which often results in intense heat production. If not dissipated properly, excess heat can degrade component reliability or even cause catastrophic failure. This is where metal core PCBs provide distinct advantages.

Metal-core PCBs, also known as MCPCBs. Metal core boards feature a conductive metal layer, usually made from aluminum or copper, sandwiched within the PCB laminate. Having such a metal center provides a direct thermal path from heat-generating components to the board edges or surfaces. This allows the metal layer to absorb and spread heat efficiently over a large area for air or liquid cooling.

Compared to conventional FR-4 or ceramic boards, metal core PCBs offer much higher thermal conductivity of 5-50 times. They enable packaging of power electronics, processors and other heat-dense components in applications like industrial motor drives, high-end servers, LED lighting, electric vehicles and renewable energy systems.

Thermal vias connect components directly to the inner metal plane for maximum heat transfer. Some boards also implement isolated thermal paths to direct heat away from sensitive analog/RF sections. Overall, metal core technology is crucial for dissipating the kilowatts of power processed inside today’s most advanced systems.

Ceramic PCB

While FR-4 and polyimide based circuit boards satisfy the needs of most consumer and industrial electronics, some applications require materials that can withstand more extreme operating conditions. This is where ceramic PCBs provide an advantage.

Ceramic circuit boards use an inorganic, non-combustible ceramic material like alumina (Al2O3) or aluminum nitride as the substrate. These provide characteristics like ultra-high heat resistance up to 250°C, great mechanical strength, non-flammability and resistance to moisture, gases and chemicals.

Ceramic-PCB Board

Ceramic PCBs are well-suited for use in demanding automotive, industrial, avionics and downhole energy applications. Their robustness allows operation in high-temperature, harsh chemical and explosive-risk environments where traditional boards cannot perform reliably.

Examples include engine control modules, avionics computers, oil & gas sensors, welding equipment, kilns and industrial furnaces. Ceramic’s durable construction also makes it suitable for demanding military and space applications with stringent safety and longevity needs.

While ceramic PCBs offer clear performance benefits over plastic boards in harsh settings, their higher material and machining costs limit general consumer use cases today. Still, ceramics remain invaluable where environmental or operational extremes are involved.

Multi-Chip Modules (MCMs)

MCMs are PCBs that integrate multiple semiconductor chips within a single package. They offer advantages such as reduced size, increased performance, and improved thermal management. MCMs are beneficial for faster data transfer, power efficiency, compactness, and efficient thermal management. Professional MCM PCB design ensures reliable communication, proper power distribution, thermal management, and manufacturability. MCMs are used in high-performance computing, telecommunications, and other advanced electronic systems.

High-Frequency PCB

High-frequency PCBs are specifically designed for applications that involve RF (radio frequency) and microwave signals. They feature controlled impedance, low signal loss, and minimized electromagnetic interference. These PCBs are optimized to minimize signal loss and maintain signal integrity at high frequencies. They utilize specialized materials with low dielectric constant and loss, ensuring efficient transmission of high-frequency signals. High-frequency PCBs are commonly used in wireless communication systems, radar systems, and satellite communication equipment.

High-Power PCBs

High-power PCBs are designed to handle high current and power levels without compromising performance or safety. They feature thicker copper traces, specialized thermal management techniques, and robust construction. High-power PCBs are used in power electronics, motor drives, and energy-related applications.

HDI PCB

High-Density Interconnect (HDI) PCBs are designed to accommodate a high density of components and interconnections in a compact form factor. They feature microvias, blind vias, and buried vias, allowing for a higher number of layers and smaller trace widths and spacings. HDI PCBs are prevalent in smartphones, tablets, and other miniaturized electronic devices, where space optimization is crucial.

IMS PCB

IMS (Insulated Metal Substrate) PCBs feature a metal core, typically aluminum, that provides superior thermal management capabilities. The metal core helps dissipate heat generated by power electronics components, ensuring their optimal operation. IMS PCBs are widely used in applications such as LED lighting, automotive systems, and power conversion equipment.

Custom Substrate PCBs

In addition to FR-4 and polyimide, there are specialized substrate materials available for PCB manufacturing. Companies like Rogers, Taconic, and Arlon offer materials with specific properties tailored for high-frequency, RF, and microwave applications. These materials provide low dielectric loss, precise impedance control, and excellent signal integrity. They are commonly used in wireless communication systems, radar systems, and satellite communication equipment.

At ELE PCB, we pride ourselves on providing exceptional service, ensuring a seamless experience from start to finish. Our dedicated team is committed to delivering on time, every time, so you can meet your project deadlines with confidence. Experience good quality, prompt delivery, and competitive pricing with ELE PCB – the ultimate solution for your electronic manufacturing needs.

Conclusion

The PCB exemplifies engineering ingenuity through enabling unprecedented circuit complexity miniaturization while establishing a universal interconnection platform. Selecting board configurations and substrates optimized according to design priorities ultimately determines electrical performance, thermal management, form-factor advantages and long-term reliability – critical success factors across industries. Continuous co-development with components further drives innovation.

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About the Author
Jeffrey Lee
I'm Jeffrey, an experienced electronics engineer. As a seasoned content creator, I bring a deep passion for PCB-related topics, allowing me to communicate complex concepts with clarity and precision, making them accessible to a wide audience.
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