Guideline

Types of PCBs: Single-Sided, Double-Sided, and Multi-Layer Boards

printed circuit board

Table of Contents

1. Introduction
2. Types of PCBs
2.1. Single-layer PCBs:
2.1.1. Characteristics
2.1.2. Applications
2.1.3. Manufacturing Process
2.2. Double-layer PCBs
2.2.1. Characteristics
2.2.2. Applications 5
2.2.3. Manufacturing Process 6
2.3. Multi-Layer PCBs 7
2.3.1. Characteristics 7
2.3.2. Applications 8
2.3.3. Manufacturing Process 8
3. Considerations in PCB Selection 8
Conclusion 9

Introduction

Different varieties of printed circuit boards (PCBs) are available, each suited to certain design requirements and purposes. Electronics designers, engineers, and hobbyists need to comprehend the distinctions between single-sided, double-sided, and multi-layer printed circuit boards. The characteristics, applications, and manufacturing processes of these three primary PCB kinds will all be covered in detail.

Types of PCBs

How many types of PCB are there? Normally, we think there are three types of PCBs, which have different production, types of materials, and applications:

1. Single-layer PCBs:

The Single-layer PCB is defined as having a solitary layer of substrate material, accompanied by a conductive layer, typically composed of copper, on one side. This conductive layer includes traces that establish the electrical connections among components. On single-layer boards, also referred to as single-sided boards, components are positioned on one side, with a conductor pattern present on the opposite side. These boards consist of a single conductive layer, typically composed of copper. The structure of a single-layer board includes a substrate layer, a conductive metal layer, a protective solder mask, and a silk screen. Such boards are commonly found in simpler electrical devices.

Single-layer PCB diagram

Fig1: Single-layer PCB diagram

Characteristics

  • Simple Design: Have a straightforward design, and components mounted on one side only
  • Limited Complexity: Less complexity, suitable for simple electronic applications with fewer components.
  • Cost-effective: Cost less to manufacture.

Applications

  • Consumer Electronics: Applicable in necessary consumer electronics for instance calculators, LED displays, TVs, refrigerators and simple control panels.
  • Low-Complexity Devices: Mostly applicable for devices with minimal circuitry

Manufacturing Process

Single-layer PCBs have a very easy and simple manufacturing process. The process diagram and brief explanation are shown below.

  • Panel Cutting
  • Copper Etching
  • Drill NPTH Holes
  • Solder Mask Printing
  • Silkscreen Printing
  • Surface Treatment
  • E-testing and Inspection

2. Double-layer PCBs

A double-layer or double-sided board PCB has two copper layers on top and bottom. Similar to the single-sided version, double-sided PCBs consist of one substrate layer. However, the distinction lies in having a layer of conductive metal on both sides of the substrate. As the name implies, this PCB type features conductive layers on both sides of the substrate, and these layers are interconnected through plated-through holes, commonly known as vias, facilitating the creation of more intricate circuit designs. Double-sided PCB is one of the most widely used PCB types in electronic applications.

Double-layer PCB diagram

Fig2: Double-layer PCB diagram

Double-layer PCBs feature a substrate material with a thin layer of conductive metal, such as copper, applied to both surfaces of the board.

Characteristics

  • With PTH Holes: With plated through holes to connect both top and bottom layers.
  • Increased Circuit Density: More complex and components can be mounted on both sides
  • Improved signal routing: Vias provide pathways for electrical connections between the top and bottom layers.
  • Versatility: versatility in terms of component placement can handle a broader range of applications while enhancing signal routing.

Applications

  • Industrial Controls: Double-sided PCBs are commonly used in industrial control systems, where moderate complexity is required.
  • Power Supplies: Devices such as power supplies, where more components and connections are needed, often utilize double-sided PCBs.
  • Lower Complex Electronics: Mostly applicable for devices with low-density drills and copper traces.

Manufacturing Process

The manufacturing process of double-layer PCBs is more complex compared to that of single-layer PCBs. The following chart shows the process of how double-layer PCBs are manufactured.

  • Panel Cutting
  • Drilling
  • PTH Plating
  • Copper Etching
  • Solder Mask Printing
  • Silkscreen Printing
  • Surface Treatment
  • E-testing and Inspection

3. Multi-Layer PCBs

Multi-layer PCBs are circuit boards with more than three conductive layers. Theoretically, they can include as many layers as required, with the largest one ever created being more than 100 copper layers. These boards are frequently employed in sophisticated devices requiring a significant number of connections. Vias, classified as Through-Hole, Blind via, and Buried via, create pathways that allow the various layers to connect. Consisting of three or more layers of substrate material interleaved with conductive layers, Multi-Layer PCBs employ vias to enable highly intricate circuit designs and improve functionality. So it is one of the most advanced types of printed circuit board.

Multi-layer PCB diagram

Fig3: Multi-layer PCB diagram

Characteristics

  • High circuit density: Complex circuits is suitable for very complex devices.
  • Enhanced signal integrity: Improved signal integrity and reduced electromagnetic interference.
  • Optimized thermal management: This allows for incorporating dedicated layers for heat dissipation, which is crucial in high-power applications.

Applications

  • High-Performance Electronics: Multi-layer PCBs are extensively used in high-performance electronics, including computer motherboards, communication equipment, and advanced medical devices.
  • Mobile Devices: The compact nature of multi-layer PCBs makes them ideal for mobile devices, where space efficiency is crucial.
  • More advanced applications: Telecommunications, industrial equipment, testing and measurement, medical devices, etc.

Manufacturing Process

Since it is a multi-layer, it is a fact that the manufacturing process is more complex compared to that of single-layer and double-layer PCBs. Let’s see the process below. The details of each process are similar to all types of PCBs.

  • Inner Layer Copper Etching
  • Layup & Lamination
  • Drilling
  • PTH Plating
  • Copper Etching
  • Solder Mask Printing
  • Silkscreen Printing
  • Surface Treatment
  • E-testing and Inspection

Considerations in PCB Selection

1. Design Complexity

An engineer will think about the complexity and usage of the application before starting design. For example, if we need to design a simple power PCB, that does not have many components and not much space limit, then we can design it as one layer or two layers to save cost. But if we need to design a complex cellphone, thousands of components need to be placed in a small area, we must use a multilayer design, such as eight to ten layers, and also blind and buried vias need to be used.

2. Space Constraints

If the PCB has fewer components and enough space to place them on the PCB surface, then we do need to design extra layers. But if we need to assemble many electronic components in a small space, trace routing on one or two layers is not possible, so we need to increase the layers to three layers, four layers and more. Plated vias, even blind and buried vias, were used to connect each layer.

3. Cost Considerations

It is obvious that multilayer circuit boards are more expensive since base costs increase because more copper layers are added. Besides, the production processes are more complex in multilayer PCB production, such as the lamination process is needed to produce a multilayer printed circuit board.

4. Performance Requirements

Multilayer PCBs have better performance in signal transmission since we can adjust the stack-up to get controlled impedance. Single-layer and double-layer PCBs have better performance for high currency applications, such as power boards, which are usually single-layer or double-layer circuit boards.

Conclusion

To summarize, the decision regarding single-sided, double-sided, or multi-layer printed circuit boards is based on the particular needs of the electronic application since different types of PCB boards have differen functions. Single-sided PCBs are appropriate for simple electrical devices because of their affordability and ease of use. Double-sided printed circuit boards offer more versatility and suit moderately complicated applications. On the other hand, multi-layer printed circuit boards are essential for cutting-edge electronics due to their high circuit density and sophisticated functionality.

The need for smaller, more sophisticated electronic systems grows as technology develops. To satisfy the changing demands of the electronics industry, engineers and designers must carefully consider the traits and uses of different types of PCBs.

. Whether an electrical design powers a basic calculator or allows complex features of a high-performance computer, choosing the right type of printed circuit board has a big impact on its success.