Classification of different types of circuit boards-TechSparks

In order to cope with different circuit environments, various types of circuit boards are manufactured and used in electronic products. If you are a novice in the electronics industry or want to understand the semi-finished products of this technology, knowing the types of PCB is a good start . In this article, eGuide will introduce you to various PCBs from three aspects: manufacturing type, layer type and material type.

PCB Classification by Manufacturing Method

Rigid PCB: The most prevalent type of circuit board is the rigid printed circuit board, also known as R-PCB. This category is typically the default reference when discussing PCBs. The term “rigid” describes the board’s primary attribute of being inflexible and unyielding, which can be both advantageous and disadvantageous. Its inherent rigidity precludes it from being easily manipulated to reduce its form factor. Nevertheless, due to its affordability and dependable performance, rigid PCB is ubiquitous in electronic devices such as calculators, radios, computer motherboards, and mobile phones.

Flexible PCB: Also known as FPC, is a type of printed circuit board that can be bent, twisted or folded without causing damage to the board. This flexibility is achieved by using a base material made of polyimide, which can be either natural or synthetic, and through specialized manufacturing processes. As miniature electronics become more popular, the demand for flexible PCB is increasing due to their ability to fit into tight spaces and unusual shapes. However, compared to rigid boards, FPC are more expensive to manufacture, making them a popular choice for high-end medical electronics, such as cardiac pacemakers and hearing aids. They can also be combined with rigid PCB to form rigid-flexible integrated PCB, which are commonly used in foldable mobile phones, laptops and other applications.

Rigid-flex PCB: also known as a hybrid circuit, is a sophisticated printed circuit board that combines a flexible board with a rigid board using highly ductile electrodeposited or rolled annealed copper conductors photoetched on a flexible insulating film. The key feature of this type of PCB is its ability to integrate the advantages and characteristics of both rigid and flexible boards, enabling the electronics to be firm while minimizing the use of connectors to achieve miniaturization. Although the cost of manufacturing a single board is relatively high, the benefits of reducing the overall cost of the project make rigid-flex PCB widely used in various circuit types, including complex applications such as missile launch detectors and global positioning systems.

PCB Types by Number of Layers

Single-layer/single-sided PCB: This type of PCB has a single conductive layer, with components and conductor patterns placed on one side of the board. The structure is simple, consisting of only the base layer, conductive metal layer, protective solder mask layer, and silk screen layer. While this type of PCB is rarely used in modern electronic applications due to their increasing complexity, their past contributions to the field of electronic manufacturing cannot be overlooked. Single-sided PCBs are known for their simplicity and ease of manufacture, making them a popular choice for simple circuits in the past.

Double-layer/double-sided PCB: Refers to a printed circuit board with copper plating on both the top and bottom sides, allowing for routing and soldering on both sides. This type of PCB is widely used, particularly for special substrates such as aluminum and ceramic boards. Although previously considered the first choice for simple devices, such as mechanical keyboards and amplifiers, due to advancements in electronic applications, it has been largely replaced by more complex PCB designs.

Multilayer PCB: Is essential components for advanced electronic applications, particularly in aerospace and military fields. They consist of more than two layers of conductive material separated by insulating layers. These layers are interconnected by vias, allowing for a compact and high-density circuit design that can handle complex signal processing and power distribution. The number of layers in a multilayer PCB can vary based on the specific application and design requirements, and can range from 4 to over 100 layers. Due to their complex manufacturing process, multilayer PCBs are more expensive than single or double-sided PCBs, but they are necessary for cutting-edge technology such as space exploration equipment, nuclear detection systems, and atomic accelerators.

Different Types of Circuit Board Substrates

FR4 PCB: It is not a specific type of PCB, but rather a code name for a flame-retardant grade. This classification includes other types such as FR1, FR2, FR3 and FR5. According to the IPC standard, FR4 PCB has a glass fiber content of 41% to 63% in the substrate, which allows them to self-extinguish after burning. It includes various thicknesses such as 0.4mm, 0.6mm, 0.8mm, 1.0mm and 1.2mm. Due to its excellent performance and cost-effectiveness, it is widely used in the electronics industry.

Rogers PCB: A high-frequency substrate material developed by Rogers Corporation, is an innovative solution that uses a high-frequency ceramic substrate material instead of traditional epoxy resin material containing glass fibers. This advanced material comes in various types such as RO 4350B, RO3000, RT6000 and more, providing a wide range of options for designers. Although the manufacturing cost is higher than traditional PCB materials, the performance benefits are well worth it. Rogers material is widely used in high-end electronic applications that require superior signal integrity and in the form of high frequency PCB, such as 5G base stations, mm microwaves, and self-driving cars. As a result, it has become an increasingly popular choice among electronics manufacturers seeking to create cutting-edge products with unparalleled performance.

IMS PCB: Short for Insulated Metal Substrate Printed Circuit Board, is a type of circuit board that utilizes a metal-based substrate with insulating properties. Manufacturers of electronic devices can choose from various types of IMS PCBs, including copper, aluminum, and iron substrates. Compared to conventional printed circuit boards, IMS PCBs offer superior thermal conductivity, electrical conducstivity, and corrosion resistance, although at a higher cost. Therefore, it is important to carefully consider the performance and cost trade-offs when selecting the substrate material for your project. Among the different types of metal-based printed circuit boards, copper substrates generally offer the best performance but also command the highest price.

Ceramic PCB: The epitome of high-end circuitry utilizing ceramics as the substrate material. While it may come with a higher price tag and delicate nature, its unparalleled attributes including lower dielectric constant, minimal water absorption, and negligible shrinkage make it the go-to option for demanding high-frequency applications. Delve into the realm of cutting-edge technology with Ceramic PCB today.