What is the lead time for FR4 PCB production?

Standard FR4 PCB production can be completed within 24 hours, depending on order size and complexity.

Do you offer assembly for FR4 PCBs?

Yes, JLCPCB provides both FR4 PCB manufacturing and full PCBA assembly services.

Can I choose different thickness and copper weight?

Yes, FR4 PCBs support multiple thickness options (0.4mm–2.0mm) and outer copper weights (1oz–2oz).

Reliable

FR4 PCBs

Made Affordable

Fast 24-hour Turnaround,supporting up to 32 layers with high-precision impedance control.In-house factories and smart manufacturing help reduce costs and boost efficiency.

2 Layers

5 pcs

Instant Quote

Instant Quote >

Introduction

Applications

Capabilities

Why Us

How to Order

Q&A

Reviews

Resources

What is an FR4 PCB?

Flame Retardant 4, or FR4, is a material grade used in PCB manufacturing. It is made of fibreglass and "4" represents the UL94 V-0 flammability standard (it must self-extinguish after being ignited). Fibreglass reinforced woven glass fibre and epoxy resin with makes it excellent for electrically insulated applications. FR4 is a widely used material due to its low cost and high reliability.

FR4 Material Overview

FR4 represents flame-retardant grade 4 glass-reinforced epoxy laminate. The material's dielectric constant and dissipation factor (loss tangent) are moderate. FR4 can be used in low-speed and high-power applications, making it the first choice for many hobbyists. This makes it suitable for general-purpose electronic designs.

Dielectric constant: around 4.5 at 1MHz (moderate). Loss tangent: around 0.02 at 1MHz (moderate). The glass transition temperature (Tg) determines how the material behaves under heat. It is one of the most important thermal properties in the classification of FR4 materials.

FR4 comes in three different temperature ranges:

Low Tg (130–140°C)
Standard Tg (150–160°C)
High Tg (>170°C)

Structure and Properties of FR4

FR-4 is a composite material used as the substrate in PCBs. Its structure is made from:

1. Woven Fiberglass Cloth (E-glass fibers): Fibreglass provides higher mechanical strength and appears as a fine woven fabric inside the laminate.

2. Epoxy Resin (flame-retardant, brominated): Epoxy acts as the matrix, binding the fiberglass together and providing excellent electrical insulation and thermal resistance.

3. Copper Foil (in PCBs): Copper foil layers are used to make tracks and are laminated onto FR-4 using heat and pressure.

Benefits of FR4 PCB Material

Cost-Effective and Widely Available

FR-4 is affordable compared to advanced laminates like Rogers. Its low cost makes it popular and the industry standard for most applications. It is globally available, making it easy to source for large production volumes.

Good Mechanical Strength

The woven fiberglass provides higher tensile strength, making it more resistant to warping, bending, and mechanical stress.

Reliable Electrical Insulation

Due to a moderate dielectric constant, it is excellent for low-frequency and higher-power applications. Additionally, the epoxy-fiberglass structure offers higher signal isolation.

How FR4 Thickness Affects PCB Performance

Thicker FR-4 increases the dielectric spacing, which raises impedance by introducing parasitic components. FR-4 thickness can be adjusted to control impedance for different circuit applications.
Thinner FR-4 has a smaller dielectric spacing between copper layers, which lowers the impedance of traces. However, the higher dielectric loss of FR-4 limits performance above a few GHz regardless of thickness.

Common Applications of FR4 PCBs

FR4 PCBs balance cost and strength for everyday electronic devices. From smartphones to wearables, FR-4 provides durable and reliable PCB solutions.

JLCPCB FR4 PCB Manufacturing Capabilities

Learn more about PCB capabilities >

Why Choose JLCPCB FR4 PCBs?

Cost-Effective Production

FR4 PCBs starting from just $2, trusted by 6M+ customers worldwide, with over 50,000 new designs manufactured daily.

Extensive Capability

Supports 1–32 layers, board thickness from 0.2mm to 3.2mm, and copper weights up to 3oz.

High Customization

Pick from 7 solder mask colors, multiple finishes, and copper thickness options to fit any project.

Fast & Global Delivery

Prototypes in as fast as 24 hours, shipped to over 200 countries worldwide.

How to Order JLCPCB FR4 PCBs in 3 Easy Steps

Frequently Asked Questions About FR4 PCB

FR4 typically has a dielectric constant of around 4.2–4.8 at 1 MHz. This property affects signal transmission speed and impedance control, making it an important factor in high-speed and RF designs.

What Customers Say About JLCPCB FR4 PCBs

95****9A Dec 1, 2025

FR-4, 4 layer, Green, HASL(with lead), PCB Prototype

This was my first PCB project and the quality and appearance of the PCBs blew me away and I can hardly believe that I can get them so cheap! They were easily solderable and worked great electrically as well!

95****1A Oct 27, 2025

FR-4, 2 layer, Green, HASL(with lead), PCB Prototype

This order was a bit different than usual, because I needed to separate analog grounds, avoid noise among many other things, I tried to make several personal boards and they didn't work correctly, I decided to try my luck if with JLCPCB it could work due to the quality of their boards, and of course it worked as it should, I was able to finish my project on time and with higher quality.

75****2A Aug 28, 2025

FR-4, 1 layer, Green, HASL(with lead), PCB Prototype

The PCBs I ordered worked perfectly for my project. I needed high-quality boards for antenna testing, and these PCBs delivered exactly what I wanted. The dimensions were precise, the pads were clean, and soldering was easy. Most importantly, the boards performed reliably during my experiments, even at higher frequencies. This made my project a success and saved me a lot of time. Delivery was also very fast, which I really appreciated. Overall, a very positive experience with this manufacturer, and I am already planning to order again for my upcoming projects

75****2A Aug 28, 2025

FR-4, 1 layer, Green, HASL(with lead), PCB Prototype

Excellent PCB service! The boards arrived on time, carefully packed, and exactly as I designed. The copper layers and finishing look very professional, and the alignment was perfect. I used these PCBs in my antenna project and they worked very well, giving stable and consistent performance. The precision of drilling and cutting was also impressive, making assembly easy. Communication from the company was good, and I always knew the status of my order. I am very satisfied with the results and I will continue to use this service for both hobby and professional projects.

Write a Review View More Reviews