FR-4 -

FR-4

FR4 is a glass-reinforced epoxy laminate widely used as the base material for printed circuit boards. It is made by impregnating woven glass fiber with epoxy resin and pressing the layers together under controlled heat and pressure. Known for its excellent mechanical strength, and moisture resistance, FR-4 material provides a stable base for copper layers and ensures consistent signal performance.

Standard FR4 is commonly used for general-purpose PCB fabrication, while higher-Tg grades are often selected for applications that require greater thermal stability, particularly in multilayer boards and lead-free assembly processes.

Layer Count : 1-68 layers
Overall Board Thickness : 0.2-10mm
Impedance Tolerance : ±10% (±5Ω if value ≤ 50Ω)
Max. Dimensions : 1400 X 610mm
Min. Dimensions : 5 X 5mm
Min. Core Thickness : 0.05mm
Inner Layer Copper Thickness : 1/4OZ – 15OZ
Outer Layer Copper Thickness : 1/2OZ ~ 30OZ

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FR4 PCB Design & Manufacturing Guides

FR4 Manufacturing Guide: Grades, Tg and Material Selection
FR4 Design Gudie: Rules, Layout and Design Steps

Choosing the right FR4 material can affect a PCB's thermal performance, electrical properties, mechanical stability, and long-term reliability. This Guide explains the material structures and properties behind FR4 PCBs, helping engineers understand how different material options relate to PCB design and manufacturing requirements. The guide covers the main components of FR4 laminates, including copper-clad laminate, prepreg, glass styles, and resin systems. It also explains important material classifications such as standard-Tg, mid-Tg, and high-Tg FR4.
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Designing a PCB with FR4 involves more than placing components and routing traces. The material's electrical and mechanical properties influence layer configuration, trace dimensions, impedance, thermal considerations, and overall manufacturability. The guide begins with the fundamentals of FR4 material and explains how its properties relate to PCB design. It then walks through the main design workflow, including defining circuit requirements, creating schematics, arranging components, routing traces, setting design rules, running Design Rule Checks, and exporting Gerber files for manufacturing.
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FR4 PCBs Manufacturing Insights

1 Layer FR4 PCB

Discover how CEZON manufactures 1 Layer FR4 PCBs, including single-sided board structures, material selection, cost-efficient fabrication processes, manufacturing challenges, and real production experience from customer orders.

2 Layer FR4 PCB

Discover how CEZON manufactures 2 Layer FR4 PCBs, including double-sided circuit structures, reliable through-hole fabrication processes, manufacturing challenges, and real production experience from customer orders.

4 Layer FR4 PCB

Discover how CEZON manufactures 4 Layer FR4 PCBs, including multilayer stackup design, layer alignment control, fabrication processes, manufacturing challenges, and real production experience from customer orders.

6 Layer FR4 PCB

Discover how CEZON manufactures 6 Layer FR4 PCBs, including multilayer stackup optimization, impedance control requirements, fabrication processes, manufacturing challenges, and real production experience from customer orders.

8 Layer FR4 PCB

Discover how CEZON manufactures 8 Layer FR4 PCBs, including advanced multilayer structures, signal integrity requirements, impedance control, fabrication processes, manufacturing challenges, and real production experience from customer orders.

FR-4 PCB Tg Grades: TG130, TG150 and TG170

The Tg, or glass transition temperature, is an important factor when selecting an FR-4 material for PCB fabrication. It indicates the temperature at which the resin system begins to transition from a rigid glassy state toward a softer state, affecting thermal expansion, dimensional stability, and reliability during PCB processing and operation.

Common FR-4 material grades include TG130, TG150, and TG170. TG130 is generally used for standard PCB applications where thermal demands are moderate. TG150 provides a higher thermal margin and is widely considered for multilayer boards and applications that undergo lead-free assembly. TG170 is a higher-Tg option for designs with greater thermal stress, repeated thermal exposure, or more demanding reliability requirements. The actual performance of each material depends on the specific laminate system and manufacturer's datasheet, rather than the Tg value alone.

CEZON supports different FR-4 material options for prototype and production builds, with material selection coordinated with board construction, layer count, copper weight, thickness, and required manufacturing specifications.

FR4 PCBs FAQs

Q1: What is the typical Tg of an FR4 PCB?

A1: Standard FR4 materials typically have a Tg around 130°C, while higher-Tg options commonly include TG150 and TG170 grades. The appropriate Tg depends on the PCB's operating temperature, assembly process, layer structure, and reliability requirements. For lead-free assembly or designs exposed to greater thermal stress, a higher-Tg FR4 material may provide a greater thermal margin.

Q2: What is the standard thickness of an FR4 PCB?

A2: 1.6 mm is the most common finished thickness for a standard FR4 PCB, but manufacturers can produce boards in thinner and thicker configurations. Common options in CEZON's manufacturing include 0.8 mm, 1.0 mm, 1.2 mm, 1.6 mm, and 2.0 mm. The suitable thickness depends on mechanical requirements, layer count, impedance requirements, connectors, enclosure constraints, and the final stack-up.

Q3: How many layers can an FR4 PCB have?

A3: FR4 PCBs can be manufactured as single-layer, double-layer, or multilayer boards. The practical layer count depends on the board's stack-up, thickness, registration requirements, via structure, and the manufacturer's equipment and process capability. Standard multilayer FR4 production commonly covers designs from a few layers to high-layer-count boards, with more complex constructions requiring tighter lamination and registration control.

Q4: What is the difference between single-sided and double-sided FR4 PCBs?

A4: A single-sided FR4 PCB has conductive copper on one side of the substrate, while a double-sided FR4 PCB has copper layers on both sides and can use plated through-holes to connect the two layers. Single-sided boards are suitable for simpler, lower-density circuits, while double-sided FR4 PCBs provide more routing space and are better suited to designs with higher component or circuit density.

Q5: Is FR4 suitable for high-frequency PCB applications?

A5: Standard FR4 can be used for many digital and moderate-frequency applications, but it is not a universal choice for high-frequency designs. Its dielectric constant and dissipation factor vary by material system, glass style, resin content, frequency, and test method. As frequency increases, dielectric loss and dielectric-property variation can become more significant, so engineers may need to evaluate the specific FR4 datasheet or consider a lower-loss laminate for demanding RF and high-speed applications.