Application Guide for Single-layer PCB Boards

In today’s highly interconnected electronic world, printed circuit boards (PCBs) are ubiquitous. From the smartphones in our hands to complex industrial machinery, PCBs are at the heart of enabling electronic functionality. Among the many types of PCBs, the single-layer PCB (also known as a single-sided board or single-sided printed circuit board) is the most basic and commonly used. Despite its relatively simple structure, the single-layer PCB plays an indispensable role in many applications.

What is a Single-Layer PCB?

As the name suggests, a single-layer PCB features conductive circuitry on only one side of the board. It is composed of a substrate material (typically FR-4 epoxy glass fiber or CEM-1/3 composite material) with a single copper layer laminated on one side. During manufacturing, the copper layer is etched to form circuit traces, pads, and component connection points. All electronic components are mounted on the non-copper side and connected to the copper traces through vias or solder pads.

Structure of a Single-Layer PCB

To better understand single-layer PCBs, it’s important to break down their core structural elements:

1. Substrate (Base Material)

This is the backbone of the PCB, providing mechanical support and electrical insulation. The most commonly used substrate is FR-4 (flame-retardant epoxy resin with woven fiberglass), favored for its excellent electrical and mechanical properties as well as cost-effectiveness. For cost-sensitive or specialized applications, CEM-1/3 (composite epoxy materials) or paper-based substrates (e.g., phenolic paper laminate) may also be used.

2. Conductive Layer

Usually made of copper foil, this layer exists only on one side of the board in single-layer PCBs. After etching, it forms the circuit traces that connect electronic components and transmit electrical signals. The thickness of the copper is a critical parameter, commonly available in 1oz, 2oz, etc.

3. Solder Mask

This is a thin layer of polymer applied over the copper layer, typically in green, red, or blue. Its primary function is to prevent solder bridging between unintended areas and to protect copper traces from oxidation and environmental contamination.

4. Silkscreen Layer

Also known as the legend or silk layer, this is printed on top of the solder mask. It provides important information such as component identifiers, polarity markings, company logos, and test point labels to facilitate assembly, testing, and maintenance. It is usually white in color.

5. Surface Finish

To prevent the exposed copper traces from oxidizing and to ensure good solderability, a surface finish is applied before shipping. Common finishes include:

HASL (Hot Air Solder Leveling): cost-effective and widely used.
OSP (Organic Solderability Preservative): environmentally friendly and suitable for lead-free soldering.

Advantages of Single-Layer PCBs

Despite their simple structure, single-layer PCBs offer several distinct advantages that make them an ideal choice for specific applications:

✅ Cost-Effective

Thanks to their straightforward structure, fewer manufacturing steps, and minimal material usage, single-layer PCBs are much cheaper to produce compared to multilayer boards. This makes them the preferred choice for high-volume, low-cost products.

✅ Simple Design

Single-sided routing eliminates the need to consider complex factors like interlayer connections or impedance matching. The design process is more intuitive and efficient, resulting in shorter development cycles.

✅ Mature Manufacturing Process

The production techniques for single-layer PCBs are highly mature, with a high yield rate and fast manufacturing turnaround.

✅ Easy Troubleshooting

Since all circuitry is laid out on a single plane, it is easier to inspect, test, and diagnose faults, simplifying maintenance and repair.

✅ Good Heat Dissipation

Components are mounted directly onto the substrate, allowing heat to dissipate more effectively. This makes single-layer PCBs suitable for low-power applications or where thermal demands are not critical.

Applications of Single-Layer PCBs

Thanks to their unique advantages, single-layer PCBs are widely used across a variety of fields:

▶ Consumer Electronics

Remote controls, calculators, LED lights, toys, coffee makers, chargers, etc.

▶ Home Appliances

Control boards for devices such as microwave ovens, rice cookers, washing machines, and refrigerators.

▶ Automotive Electronics

Used in non-critical, low-complexity modules such as lighting control, power window systems, and door controls.

▶ Medical Devices

Low-cost, non-implantable medical diagnostic and monitoring equipment.

▶ Lighting Products

LED lighting modules, light strips, and related assemblies.

▶ Simple Industrial Control

Basic sensor modules, timer circuits, or control units used in light-duty industrial applications.

Comparison Between Single-Layer and Multi-Layer PCBs

Understanding the value of single-layer PCBs also helps clarify how they differ from multi-layer PCBs:

Feature	Single-Layer PCB	Multi-Layer PCB
Structure	Conductive traces on only one side	Traces on two or more layers, connected via vias
Cost	Low production cost	Higher production cost
Design Complexity	Simple; suitable for low-density circuits	Complex; ideal for high-density and high-speed circuit designs
Board Size	Relatively larger, as all routing is on a single plane	More compact; enables complex circuits within limited space
Signal Integrity	Lower; more susceptible to noise and electromagnetic interference	Higher; improved through optimized layout and dedicated ground/power layers
Heat Dissipation	Better; heat dissipates easily from components	Poorer; heat can accumulate between layers, requiring advanced thermal solutions
Applications	Simple, low-cost, low-density electronics	Complex, high-performance, high-density, high-speed systems (e.g. motherboards, smartphones, servers, aerospace electronics)

Key Steps in Single-Layer PCB Manufacturing

The production of single-layer PCBs is a precise and highly automated process, involving the following key steps:

Cutting
Copper-clad laminates (CCL) are cut into the required panel sizes.
Pattern Transfer (Outer Layer Patterning for Single-Layer PCBs)
The copper surface is cleaned, and photoresist is applied. Through UV exposure and development, the circuit pattern is transferred onto the copper layer.
Etching
Unwanted copper is removed using a chemical solution (e.g., ferric chloride), leaving only the desired circuit traces and pads.
Stripping
The remaining photoresist is stripped off to expose the copper circuit.
Drilling
CNC drilling machines are used to drill component holes, mounting holes, and vias (if needed for mechanical purposes).
Solder Mask Application
Solder mask ink is applied to the board surface. After exposure and development, only the areas requiring soldering remain uncovered.
Silkscreen Printing
Component designators, polarity markings, logos, and other identifiers are printed onto the board.
Surface Finishing
Exposed copper pads are treated with a surface finish (e.g., HASL or OSP) to prevent oxidation and enhance solderability.
Profiling
The finished PCB is cut into its final shape using CNC routers or stamping dies.
Electrical Testing
Electrical continuity is verified via flying probe or fixture-based testing to ensure there are no open circuits or shorts.
Final Inspection & Packaging
Visual inspection is performed to confirm product quality. Boards that pass inspection are packaged for delivery.

Key Considerations When Choosing a Single-Layer PCB

Before selecting a single-layer PCB for your project, engineers and designers should carefully evaluate the following factors:

Cost Budget
If the project is highly cost-sensitive and the circuit is not functionally complex, a single-layer PCB is typically the most economical option.
Circuit Complexity and Density
For simple circuits with a low component count and no high-speed signal requirements, a single-layer PCB is sufficient. Complex or high-density circuits usually require multi-layer designs.
Signal Integrity Requirements
If the circuit operates at low frequencies and has minimal signal integrity concerns, a single-layer PCB is acceptable. High-speed digital or high-frequency analog circuits generally benefit from multi-layer PCBs with dedicated ground and power planes.
Size and Space Constraints
If the design must fit within a compact form factor while supporting a high number of components, a multi-layer PCB may be the better choice.
Thermal Requirements
For circuits with low heat generation, single-layer PCBs typically offer adequate heat dissipation.

Future Outlook for Single-Layer PCBs

Despite ongoing advancements in multi-layer and HDI (High-Density Interconnect) PCB technologies, single-layer PCBs are far from becoming obsolete. With the growing proliferation of IoT devices, smart home products, and various types of sensors, the demand for low-cost, simple, and reliable electronic modules continues to rise. Thanks to their inherent cost and manufacturing advantages, single-layer PCBs will remain an essential solution in these niche markets.

Looking ahead, single-layer PCBs are expected to evolve in the following ways:

More Eco-Friendly Materials
Adoption of environmentally friendly base materials and greener manufacturing processes to reduce environmental impact.
Smaller Footprint
With the continued advancement of SMT (Surface-Mount Technology) and miniaturization of electronic components, single-layer PCBs will achieve higher levels of integration even in compact designs.
Integration with Flexible PCBs
In certain applications, combining single-layer rigid PCBs with flexible PCBs can enable more versatile and space-efficient designs.

Conclusion

As a foundational element in the electronics industry, single-layer PCBs continue to play an irreplaceable role across a wide range of electronic products. Their unique advantages—cost-effectiveness, straightforward design, and mature manufacturing—make them a practical and reliable choice for many applications.

Understanding their structure, benefits, application scenarios, and the differences from multi-layer PCBs enables engineers and product developers to make well-informed design decisions. In the rapidly evolving electronics landscape, single-layer PCBs will remain a vital force in supporting innovation and the widespread adoption of technology.