Meaning of FR-4: Composite PCB Manufacturing Material and Rating Unit.
In the industry of electronic engineering, various types of printed circuit boards are used, each with its unique characteristics and applications. For instance, Rogers is used in HF circuits, Teflon is used in RF circuits, and so on. The names of these circuit boards are typically based on their substrate materials, and FR4 PCB, in particular, has a dual meaning:
- As a manufacturing material, it refers to a composite material with exceptional thermal and electrical properties, namely, a glass fiber reinforced epoxy laminate.
- As an evaluation grade, it refers to the material’s ability to resist fire and self-extinguish in the event of a fire, along with other grades such as FR1, FR2, and FR3.
Traditional PCBs use glass-reinforced epoxy resin as the substrate material, providing an old structure. In contrast, FR4 is a new PCB manufacturing material that adheres to UL94V-0 standards. If your electronics project requires the use of FR-4 PCBs, FS Technology can help you by offering the industry’s most competitive price list.
Reliable FR4 PCB Manufacturer - FS Technology
- More Choices
FS Technology has several years of experience in PCB manufacturing and can meet the needs of most customers. Compared to other manufacturers, we offer a wider range of options, such as various thicknesses and layers, multiple surface treatments, and different substrate materials. This makes it more advantageous for you to customize FR4 PCB to your specific requirements.
Regarding materials, we source our laminate and prepreg materials from top suppliers such as Isola, Taconic, Panasonic, and Shengyi Technology. This ensures that we provide high-quality materials that are consistent and reliable, resulting in superior circuit board.
- Wide range of services
Unlike traditional Chinese FR4 PCB manufacturers, we are a service provider that integrates industry and trade. Our company structure comprises a manufacturing workshop, assembly workshop, sales department, purchasing department, technical department, and after-sales processing department. This means that we offer more service options, such as IC programming, design, assembly, and manufacturing, which can be either turnkey or standalone services.
- Quality and Reliability
We are a reliable company that can provide various industry certifications, including the conventional ISO9001 and 14001, as well as the “International Automotive Industry Technical Specifications” IATF16949 and “Medical Device Quality Management System for Regulatory Requirements” ISO13485. However, at FS Technology, qualification certification is only one aspect of demonstrating our capabilities to customers. We also formulate stricter operating specifications and testing services, which are essential in ensuring the smooth progress of your PCB project.
- Delivery Time
Delivery time is a crucial concern for customers when choosing PCB manufacturing services. For FR4 PCB prototype orders, we prioritize faster shipping to Chinese ports, which typically takes only a few days. We understand that customers are eager to receive their goods promptly. When you submit your order request to us, we will provide you with an estimated delivery time based on your receiving address, the number of boards, and the level of complexity.
- Customer Support
At FS Technology, we strive to impress our customers with our exceptional service and quality. To achieve this, we provide tailored customer support services to meet the unique needs of each customer. Our customers can reach their dedicated customer service representative through phone, email, chat, or social media platforms 24/7. If any technical issues arise, they are promptly forwarded to our technical department and resolved in a timely manner.
Selection of F4 PCB Board
When choosing different types of circuit board, there are multiple strategies to consider, such as referencing performance parameters. The following table shows the parameter table for conventional FR4:
|Test Items||Processing Conditions||Unit||Performance Parameter|
|Reference Value||Typical Values|
|Volume Resistivity||After Immersion||MΩ-cm||≥10^6||2.0*10^8|
|Surface Resistivity||After Immersion||MΩ||≥10^4||3.0*10^7|
|Dielectric Constant (1MHZ)||C-24/23/50||—||≤5.4||4.7|
|Dielectric Loss Angle (1MHZ)||C-24/23/50||—||≤0.035||0.01|
- All test data comply with IPC-4101/92 standard
- Sample thickness: 1.6 mm
- C=humid condition
- D = Immersion in distilled water condition
- E=temperature condition
- Tg=Glass transition temperature, the plate undergoes softening deformation at high temperature and is accompanied by a sharp decline in mechanical and electrical properties
High TG FR4
High TG FR4 is a type of FR4 PCB that belongs to the category of FR4 PCBs with higher curing temperatures. It is characterized by having a higher glass transition temperature (TG) than standard FR4. The glass transition temperature is the temperature at which a material transitions from a rigid, glass-like state to a softer, rubber-like state. With a TG of approximately 170-180 °C, High TG FR4 has a higher TG than the typical TG of standard FR4, which is 130-140 °C.
High TG FR4 is often considered the best choice for lead-free assembly and for securing the board from variable temperature conditions. It is commonly used in projects and applications that require high temperatures, such as power electronics, LED lighting, and automotive electronics.
The term “halogen-free” refers to the absence of the periodic table elements bromine, iodine, and chlorine in the substrate. While halogen-containing flame retardant materials provide good flame retardancy, they produce a large amount of toxic gas that is harmful to humans after combustion.
To prevent the damage caused by halogen elements, FS Tech uses phosphorus and phosphorus nitrogen instead. These materials are also suitable for lead-free soldering and have a glass transition temperature of about 150°C and a decomposition temperature of 330°C. Halogen-free substrates are ideal for devices that produce hazardous smoke when burned, such as technical instruments, and are commonly used in mobile communication systems and related projects.
FR4 Multilayer PCB
The FR-4 PCB is the most commonly used board in the electronics industry due to its ease of manufacturing and the extensive experience that most manufacturers have in using it. It is typically constructed as a multilayer structure, making it a suitable choice for projects that require FR4 multilayer boards. FS Technology can provide a lower price list and manufacture multilayer PCB with 1–56 layers.
Moreover, the FR4 multilayer board is composed of multiple layers of conductive materials separated by insulating layers. It exhibits good mechanical properties and enables the realization of more complex and compact designs. PCBA processing plants can easily solder components to PCBs through SMT assembly and through hole PCB assembly, thereby creating functional electronic circuits.
Thick Copper FR-4 PCB
Thick Copper FR-4 PCBs are made from the same base material as regular FR-4 PCBs, but the copper layer on the board is thicker, hence the name. According to the PCB Copper Thickness Guidelines, thicker copper layers can improve electrical conductivity and heat dissipation, making them the first choice for applications that handle higher currents and power, such as power supplies, motor control circuits, and LED lighting.
When designing Thick Copper FR4 PCB, it is important to consider the additional weight and cost of the thicker copper layers. Additionally, the board may require special manufacturing techniques, such as controlled impedance routing, to ensure proper performance.
Rigid-Flex FR4 PCB
Rigid-Flex FR4 PCBs are a type of hybrid printed circuit board that combines the durability and rigidity of FR4 material with the flexibility of a polyimide film. This allows for the creation of PCBs that can bend and twist without breaking, while also maintaining a rigid structure in certain areas. Rigid Flex PCB is ideal for applications that require both flexibility and durability, such as medical devices, aerospace, and military applications.
The design of a Rigid-Flex FR4 PCB is complex and requires careful consideration of the placement of the rigid and flexible areas, as well as the routing of the traces and vias. The use of specialized tools and software, such as 3D modeling and simulation software, can help with the design process. The manufacturing process for Rigid-Flex FR4 PCBs also requires specialized techniques, such as laser drilling and controlled depth routing, to ensure the proper alignment and functionality of the rigid and flexible layers.
Using FR-4 PCBs in electronics projects?
FR4 PCB Material Properties
In PCBs, the TG value is an index used to measure the board’s heat resistance. A higher TG value indicates a higher temperature rating, while a lower TG value indicates a lower temperature rating. PCBs made of FR4 material can withstand an operating temperature of up to 130°C, which sets a high standard for PCB temperature ratings. However, FS Technology recommends not exceeding 100°C, as even if the ambient temperature does not reach the rated value, the circuit board’s physical characteristics may change. As large numbers of components with different thermal tolerances are assembled onto the PCBA, it is challenging to consider all components’ heat exposure. Additionally, FR4 has low thermal conductivity, and poor design choices may cause components to heat up and become damaged. Due to FR4’s excellent electrical and mechanical properties, it is commonly used in industrial PCB, but it is crucial to consider the temperature rating of FR4 when designing circuits.
The thickness of an FR4 PCB can vary depending on the specific application and design requirements. Generally, FR4 PCBs are available in thicknesses ranging from 0.2mm to 6.0mm or more. Thinner PCBs are often used in applications where space is limited, such as in mobile devices or wearable technology, while thicker PCBs are used in applications that require greater durability and strength, such as in industrial or military equipment. The thickness of an FR4 PCB can also affect its electrical properties, such as impedance and capacitance, so it’s important to carefully consider the design requirements and choose the appropriate thickness for the application.
FR4 materials are considered to have poor thermal conductivity, with a thermal conductivity of only 0.3W/(m·K), compared to copper’s high thermal conductivity of 385W/(m·K), and the general range of 10~45W/(m·K) for most materials. The thermal coefficient of metal materials is the highest. Several factors affect the thermal conductivity of an FR4 PCB, including Vias, Copper Traces, and Inner Layers.
Vias are holes created on the surface of the PCB to help dissipate heat. The principle is to spread the heat through the components to the surface of the entire PCBA by punching holes on the bare board and then transferring the heat to the external environment through convection and radiation transfer. FS Tech believes that this is only a way to treat the symptoms and not the root cause. If only vias are used as a heat dissipation measure, a small number of vias cannot effectively solve the problem. When the number of vias reaches a certain value, the benefits will be greatly reduced because the heat will collect in the position of the via, causing uneven heating of the entire circuit board.
Traces also play a crucial role in good thermal conductivity. If the traces are connected properly, heat can dissipate easily. For high heat dissipation, the traces must be completed.
The inner layers of the board also play a role in heat dissipation. If the layers are thicker, thermal conductivity will be reduced.
The density of FR4 PCB depends on the thickness and number of layers of the board. Typically, the density of FR4 material is 1.85g/cm³, but the actual density of the PCB may vary depending on the design and manufacturing process.
The number of layers in the PCB can also affect its density. A single-layer FR4 PCB will have a lower density than a multi-layer FR4 PCB because the latter has more layers of copper and insulating material. The thickness of the copper layers can also contribute to the density of the PCB, with thicker copper layers increasing the overall weight and density of the board.
FR4 PCBs have low hygroscopicity, which means they absorb only a small amount of moisture from the environment, helping to maintain their dielectric properties even in humid conditions. Moisture absorption can cause changes in the electrical properties and mechanical strength of the PCB, potentially leading to problems such as delamination, microcracks, and electrical shorts.
To avoid such situations, FS Technology takes effective measures:
- Storing the PCBs in a dry environment with a relative humidity below 50%;
- Wearing gloves when handling the boards to prevent transfer of oil and moisture from the skin;
- Following proper baking guidelines in wet conditions.
FR4 PCBs have good mechanical properties, making them suitable for a variety of applications. They have high strength, stiffness, and dimensional stability, and are resistant to impact, vibration, and shock. The tensile strength of FR4 ranges from 345-414 MPa, while the flexural strength ranges from 483-586 MPa. The coefficient of thermal expansion (CTE) of FR4 is low, typically around 14-18 ppm/°C, making it dimensionally stable even under temperature changes.
Fr4 PCB VS Other
FR1, FR2, FR3, and FR4 are four different types of flame-retardant materials used in the manufacturing of printed circuit boards (PCBs).
- FR1 is made of phenolic resin and paper. It has a low cost and is commonly used in low-voltage and low-frequency applications.
- FR2 is made of phenolic resin and cotton. It has better mechanical properties than FR1 and is used in applications that require higher voltage and frequency.
- FR3 is made of epoxy resin and paper. It has better thermal and mechanical properties than FR1 and FR2 and is used in applications that require higher performance.
- FR4 is made of epoxy resin and glass fiber. It is the most widely used material in PCB manufacturing due to its excellent electrical, mechanical, and thermal properties. It is suitable for high-frequency and high-performance applications.
Rogers VS Fr4
- Rogers is superior to FR4 when it comes to managing high temperatures;
- FR4 is more susceptible to signal loss compared to Rogers;
- FR materials have higher dissipation factor values than Rogers;
- In terms of impedance control, Rogers has a different dielectric constant than FR4;
- FR4 is more cost-effective than Rogers;
- FR4 has a lower dielectric constant value than Rogers PCB.
Aluminum VS Fr4
- Aluminum PCB have better thermal conductivity compared to FR4, enabling them to dissipate heat more effectively, making them an excellent choice for applications that require high-power components that generate a lot of heat.
- FR4 is a cost-effective alternative and is cheaper than aluminum.
- Due to its good mechanical strength and ability to accommodate more components, aluminum substrates are easier to PCB assembly.
- Aluminum is much heavier than FR4, which can be a disadvantage in weight-sensitive applications, such as the aerospace or automotive industries.
- Aluminum has the ability to shield circuit components from electromagnetic radiation.
Ceramic VS Fr4
- The thermal conductivity of FR4 is much lower than that of ceramic substrates such as alumina, aluminum nitride, or silicon carbide.
- FR4 PCBs require vias, metal layers, and cooling elements to achieve heat dissipation, while ceramic PCB do not require these elements.
- FR4 PCBs have excellent electrical insulation performance and are cost-effective, while ceramic PCBs have high-temperature resistance.
- Ceramic substrate materials are more suitable for high-price and high-profit electronic projects such as medical PCB, military electronic PCBs, or the aerospace industry, while FR4 is more suitable for consumer electronic products.