FS Technology, which is located in Shenzhen, China, is a PCBA processing company that specializes in turnkey PCB assembly. Along with our expertise in PCB assembly service, we also offer comprehensive PCB manufacturing services to our customers. Our bare board manufacturing capabilities include up to 1-58L rigid board, 1-6L flex board, 2-10L rigid-flex board, and 1-6L aluminum/copper board (36/10). In addition to these PCB types, we also offer almost all other commonly used circuit boards in the industry, and provide high-quality materials that meet industry standards and requirements. If you would like to learn more about the types of printed circuit boards we can supply and our detailed capabilities, please click on the link to visit the corresponding page.
Different Types of Circuit Boards
Hard and Soft Category of PCB
Contrary to popular belief, PCB is not solely rigid in nature. Apart from traditional rigid boards, they can be categorized into different types based on their softness and hardness. These categories include rigid boards, flexible boards, semi-flexible boards, and rigid-flex boards, each serving distinct purposes with its own set of properties, characteristics, advantages, and disadvantages. Let’s delve into the details of these four types of PCB.
Rigid PCB
Rigid PCB is perhaps the most commonly manufactured type of circuit board. They have a sturdy and inflexible structure that cannot be altered to different shapes or forms once the construction is complete. This type of circuit board has a straightforward design and is relatively easy to manufacture. There is no limit on the number of layers, and circuits with a single-layer, double-layer, or multi-layer can be easily constructed. The structure of a rigid PCB typically includes three parts: Substrate, Solder Mask, and Silkscreen. It is a very common type of circuit board, and the green motherboard found in our computers is a good example of a rigid board.
This simple and inexpensive type of circuit board can be found in almost every electronic product, such as X-ray machines, mobile phones, laptops, sensors, and communication equipment, among others.
Flexible PCB
This type of foldable circuit is known as a flexible circuit, flexible PCB, or FPC. It is typically composed of polyimide or polyester film with a polymer coating that protects the conductive circuit on its surface. Using this type of PCB in electronic projects offers the advantage of being able to modify and change it into different structures and shapes, thus reducing the size of the project and the number of components required, leading to cost savings. However, due to its flexible characteristics, it doesn’t offer higher reliability, so it is often used in combination with rigid boards to form a wider range of forms.
Flexible PCB is commonly used in various industries. In addition to consumer electronics, radio frequency and microwave applications, constructed medical PCB play a pivotal role in modern medical equipment.
Semi-Flex PCB
Semi-flex PCB uses deep milling technology to thin the board to give the rigid board a small amount of bending ability. This circuit type is built using traditional FR4 material and is not truly a flex PCB for this reason.
Semi-flex PCB is used less frequently in equipment and is usually used as an economical alternative to rigid-flexible PCB. However, it should be noted that they are far inferior to rigid-flexible PCB in terms of bending and reliability.
Rigid-Flexible PCB
The rigid-flex PCB is a more complex type of PCB that incorporates both the rigid and flexible PCB types mentioned earlier into a single platform. Electronics manufacturers create circuit boards with both flexible and rigid qualities depending on the requirements of the project. These boards consist of a flexible portion attached to a rigid material that helps to close the conductor layers and create a compact PCB. Although rigid-flex circuits are more costly, they eliminate the need for connectors and result in lighter and more contemporary circuit boards for electronic products.
Due to its difficulty in construction and high cost, it is usually used in high-tech equipment, such as military equipment, wearable medical electronics, etc. Of course, it can also be used as a consumer electronics PCB. One example is a folding screen mobile phone.
Layer Type of Circuit Board
Printed circuit boards can be manufactured with different numbers of layers depending on the requirements of the project and its structure. The layers can include single layer, double layer, and multi-layer options. While manufacturers strive to meet customer demands for the number of layers, they may be limited by their own manufacturing capacity and available materials. The following are the categories of PCB based on the number of layers:
Single Layer PCB board
The single-sided or single-layer PCB board is named so because the components of this simple circuit board are gathered on one side of the board, and its wires are gathered on the other side. It has only one layer of copper on the substrate material. Due to its cheap price and simple creation, this type of board is very commonly used in the electronics industry. As these boards come in a single layer, there is no intersection between the conductive layers, which means they require less space than multi-layered boards. Both SMD and DIP packages can be used in this PCB.
Pros:
- It is the easiest to design and manufacture of all circuit boards;
- Due to its simple structure, it is extremely cost-effective for mass production;
- The testing process is simple and it is easy to modify after problems are identified.
Cons:
- The number of electronic components that can be used is limited;
- The scope of application is small, and it is not suitable for complex applications.
Double-Layer PCB
The board that has two copper layers on each side to make connections between components is called a double-sided or double-layer PCB board. This kind of PCB has a conductive layer and a solder mask on each side of a single base layer. Electronic components are soldered on both sides of the PCB. Conductive holes are drilled and used to connect the two conductive layers.
Advantages of Double Sided PCB
- Reduces the size of PCB;
- Increases the density of PCB;
- Brings more flexibility to design;
- Allows for more efficient fabrication of complex designs;
- Cost-effective, aids in routing where there are more components and less space clearance.
Multilayer PCB
If a PCB has more than two conductive layers, it is called a multilayer PCB. Due to the unique PCB manufacturing process of these boards, the number of layers is usually an even number. The structure of a multilayer PCB is like a sandwich, with multiple double-sided layers and insulation materials between them. All layers are interconnected with conductive holes, similar to a double-sided PCB. Higher layer counts allow electronic engineers to design more complex products, but also make their jobs more challenging.
Advantages of Multilayer Board Design
- Increase design flexibility
- Prerequisite for the production of smaller and more powerful electronic devices;
- Allows high-speed layouts that cannot be achieved with single- or double-layered boards.
Three Layer PCB
Layer stackups are typically designed with an even number of layers due to their specific characteristics. However, 3-layer PCB stands out as a unique exception. In circuit design, a 3-layer PCB typically consists of one signal layer (usually the top or bottom layer), one ground layer, and an intermediate signal layer.
It’s often said that existence implies rationality. However, from the perspective of FS Technology, there may not be a compelling reason for the existence of 3-layer PCBs. In terms of manufacturing costs, the price of a 3-layer PCB is usually the same as that of a 4-layer PCB. So, why not opt for the enhanced performance of a 4-layer PCB?
Types of PCB Substrate Materials
FS Technology offers various types of materials for PCB creation, which are explained here. Almost all the types of materials used in PCB can be ordered from us to use in your projects. We will help you select the required materials based on your project’s needs and design configuration.
FR-4 (High TG, Halogen-free)
Traditional FR-4 PCB: FR-4 stands for Flame Retardant number 4 and is made of woven glass reinforced epoxy resin. It provides strength and resistance to moisture, and is used in PCB to provide insulation and separate copper layers to make connections, which enhances the strength of the boards.
High TG FR-4 PCB: High TG refers to the glass transition temperature, which is the temperature at which the substrate transitions from a rigid to a soft state. The TG value for conventional FR-4 PCB is typically around 130 to 140 °C, while medium TG values are around 150 to 160 °C, and high TG values are above 170 °C. High TG PCB can absorb more heat and have better water resistance than normal FR-4.
Halogen Free FR-4 PCB: Halogen-free materials do not contain halogen elements, such as fluorine (F), chlorine (CL), bromine (Br), and iodine (I), which can release toxic substances when burned. Using halogen-free PCB can prevent the release of these substances in the event of a short circuit. In addition to being more secure, this type of circuit board also has the following advantages:
- Good heat resistance, withstanding temperatures up to 150 °C;
- Strong insulation performance, withstanding a breakdown voltage of 40KV;
- Excellent water absorption and moisture resistance, ensuring a longer lifespan.
Metal Core
In most cases, the construction material of a PCB is an insulating material, which resists the flow of electric current. As mentioned above, FR4 is a common insulating material. However, in high-power circuit environments where it is necessary to use high currents to achieve circuit functionality, insulating materials struggle to provide the required heat dissipation. In comparison, a metal material is highly thermally conductive. A PCB constructed using metal as the substrate is known as a metal-core PCB, with the most common metals being aluminum and copper:
Aluminum-Based PCB: This board consists of a thin conductive layer on an aluminum substrate. It is also referred to as an aluminum-clad or aluminum-based PCB. The structure of an aluminum PCB is similar to that of other types of PCB, with a copper layer for soldering, a solder mask, and a silkscreen for component identification. Although this type of PCB is very common, it is typically constructed as a single or double layer, as manufacturing multilayer aluminum PCB is complex and challenging. Aluminum PCB are often used in applications that require efficient heat dissipation, such as LEDs.
Copper-Based PCB: This is the most expensive type of metal circuit board, with the highest-quality heat dissipation. It is commonly used in high-frequency circuits, areas with large temperature differences, precision communication equipment, and the construction industry. Copper-based PCB have a 4-layer structure, and their base material is referred to as a CCL. Their construction is similar to that of FR4 boards.
Polyimide
The term polyimide, abbreviated as PI, is an organic high molecular polymer material composed of two parts: “poly” meaning polymer and “imide” meaning imide monomer, which is combined to create this material. It has excellent heat resistance, with a temperature range reaching above 400 °C and a continuous high-temperature resistance range of about 200-300 °C. The dielectric loss is only 0.004-0.007, making it belong to the F to H-level insulation category. The common types of polyimide include 2nd Generation, 3rd Generation, and Filled Polyimide.
Ceramic
A ceramic PCB is a printed wiring board made with thermally conductive ceramic powder and organic binders, prepared at a temperature lower than 250 °C, with a thermal conductivity of 9-20 W/m.k. During the manufacturing process of the ceramic substrate, a copper layer is attached to the alumina or Sic by applying high temperature. This board has superior heat transfer properties compared to other boards and excellent electrical features. Based on the constituent materials, this circuit board can be divided into three categories: alumina ceramic PCB, beryllium oxide ceramic PCB, and aluminum nitride ceramic PCB. Additionally, it can be divided based on the proportion of alumina, into 75%, 96%, and 99.5% alumina ceramic PCB.
Teflon
Teflon PCB, made from PTFE (polytetrafluoroethylene), is a synthetic resin material commonly used in high-speed electronic projects, especially for circuits that utilize radiofrequency (RF) and microwave signals. It effectively addresses the limitations of traditional materials. PTFE is renowned for its non-stick and non-reactive surface, making it suitable for environments with significant temperature variations. Additionally, it boasts lower loss factors and a lower coefficient of thermal expansion.
Rogers（4003/3003 /4730G3/4835T/4830/4350/5880）
Rogers PCB is a special type of circuit board material developed and manufactured by Rogers Corporation. This kind of substrate is primarily used in high-speed and high-frequency applications and is characterized by a structure consisting of a metal foil, typically copper or aluminum, sandwiched within an epoxy resin core. The distinctive features of Rogers PCB include consistent temperature characteristics, low dielectric loss, and excellent dielectric strength. It can also be combined with common FR4 substrates to achieve various dielectric constant values, typically ranging from 2.55 to 10.2.
Taconic
This is a circuit board that uses Taconic (TLX-8, TLX-9) as the substrate material. These substances are a type of ceramic-filled PTFE. Taconic Corporation became a leading supplier to the food processing industry by pioneering the manufacture of PTFE-coated fabrics and other high-temperature/nonstick materials. Taconic PCB laminates can be milled, plated, and sheared using standard methods. Like other high-frequency materials such as Arlon and Rogers, Taconic is a microwave/RF PCB materials that are often used in telecommunication and aerospace projects.
Arlon
Arlon (35 N, 85 N) is a PCB material used for making high-performance laminates and prepreg materials for various PCB-based projects. These materials offer better features such as thermal and mechanical strength compared to FR4. This substrate exists in different types such as woven glass and non-woven aramid. Common applications of Arlon include military instruments, heat sinks, and HDI in some communication projects.
Panasonic
The Panasonic R-5575 is a multi-layered PCB structure made of high-speed, halogen-free material with low loss. This material is commonly used in radio antennas and in miniaturizing PCB boards. Other features of the Panasonic R-5575 include good thermal behavior, anti-aging properties, and water resistance. Its surface resistance value is 1 x 10^8 Ω.
CEM-1
CEM-1 is a substrate material that is specifically used for the construction of industrial single-layer PCBs. The primary reason for using CEM-1 in single-layer boards is its cost-effectiveness, which makes it an ideal choice for cheaper and simpler PCBs. The construction of these materials is straightforward, and they have the ability to accommodate a large number of components, allowing for the assembly of many components on a single layer PCB.
CEM-3
This material is used for two-layer boards that come in white color, and have a glass epoxy configuration. Although its mechanical strength is less than FR4, CEM-3 is more cost-effective and can be a good alternative to FR4.
PCB Classified by Function
High Frequency
High-frequency PCB is a premium circuit board designed for the efficient transmission of large data volumes. Electronic products utilizing this circuit board type share the following common characteristics:
- Signal transmission speeds exceeding 12Gbps.
- Utilization of a high-frequency PCB type.
High-frequency PCB should possess the following key attributes:
- Small and stable DK values, such as high or fluctuating DK values caused by frequency variations can lead to signal transmission delays.
- DF value is critical as it impacts signal transmission quality.
- The thermal expansion coefficient of high-frequency PCB should match that of copper foil to prevent copper foil separation resulting from alternating hot and cold operational temperatures.
- Low water absorption to preserve DK and DF values in humid environments.
- Resilience to heat, chemicals, impact, and peeling, akin to other PCB types.
Materials employed in crafting high-frequency PCB include:
- Rogers 4350B HF, RO3001, RO3003.
- ISOLA IS620 Electronic Fiber Glass.
- Taconic RF-35 Ceramic.
- Taconic TLX.
High-frequency PCB find applications in various scenarios, including:
- High-frequency data lines.
- Automotive radar systems.
- Cellular telecommunication systems.
- Power amplifiers and antennas.
- E-band point-to-point microwave links.
- RFID tags.
- mmWave applications.
IMS PCB
As companies increasingly prioritize the thermal management performance of PCB, IMS PCB – a circuit board type known for its efficient thermal management capabilities – has gained significant recognition. Thanks to this unique advantage, IMS PCB has the potential to unleash the full power of electronic products. FS Technology has outlined the advantages and application areas of this PCB board type as follows:
- The IMS substrate exhibits a thermal conductivity that is 8–12 times that of FR-4, boasting a remarkable thermal conductivity as high as 2.2/m·K.
- While the use of SMT PCB assembly reduces the product’s volume by increasing component density, it can also compromise the PCB’s heat dissipation capabilities. IMS Insulated Metal Substrates expertly address these limitations, playing a crucial role in dissipating heat generated during the operation of electronic components and accelerating the reduction of operating temperatures.
- IMS’s metal substrate can carry higher current levels with the same thickness and trace width, supporting voltage levels up to 4500V.
- This PCB type is typically filled with materials such as aluminum oxide, aluminum nitride, boron nitride, magnesium oxide, or silicon oxide.
HDI PCB
This type of circuit board adopts high-density interconnection technology and employs a conventional double-sided PCB as the substrate, which is then created through multiple layers of lamination. Compared to traditional FR-4 circuits, this board is thinner, lighter, smaller, and more densely packed. With the growing demand for electronic product miniaturization, electronics manufacturers have been enhancing their capabilities in micro vias, line width, line spacing, and pad manufacturing, leading to the transition to HDI PCB. This circuit board type is frequently used in high-end control systems.
Summarize
Different types of printed circuit boards that FS Technology can produce has greatly explained. We are offering PCB-based services with great accuracy and high-quality features since it is a reliable PCB provider in the industry that offers PCB manufacturing services to users’ requirements and demands. FS Technology is serving as one-stop solution PCBA service provider and also an overseas projects manager. We are equipped with professional engineers and the latest machines that are commonly used in the PCB industry to create professional PCBs.
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