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PCB/PCBA knowledge
FR4-PCB--The-Design-and-How-It-Can-Be-Used-For-Multiple-Applications

Based on their intended use, PCBs come in different variations. Considering this fact, the FR4 material was introduced to advance the features of PCB as it acts like a fire retardant. This ability make FR4 PCB to be used in different sites where short circuits are needed to prevent and also in other applications.

In this article, we’ll find out what FR4 PCB is, its benefits, and how it can be used for multiple applications.

Table of Contents

What is FR4 PCB?

what is FR4

An FR4 PCB is a PCB (printed circuit board) made of fiberglass-reinforced epoxy resin that acts as a fire retardant and makes the material resistant to heat and friction, making it ideal for use in high-end electronics.

FR-4 is made from thin-film laminates used in PCBs, which gives the board its structure. A prepreg layer is laminated between the center core and copper layers on top and bottom of a multilayer PCB, operating as an electrical insulator between the two copper layers.

Benefits of FR4 PCB

The primary benefit of using FR-4 PCBs instead of other kinds of PCBs is that they can be used under extreme conditions without damage to the board or its components, making it less likely to catch on fire when exposed to flames or other hazards.

Secondly, it is highly resistant to flexing, which means it can withstand repeated flexing without breaking down. This makes it ideal for products like motors or solar cells subjected to unique stress levels.

Lastly, this material is also more cost-effective than ceramic PCBs, making it the ideal choice for many applications.

Types of FR4 materials and parameters

types of FR4

Types of FR4 Materials:

1. Standard FR4: This is the most basic yet widely used type of FR4 material and has good thermal stability and mechanical strength, making it suitable for use in a wide range of applications.

2. Low Loss FR4: This type has a lower dielectric constant, which makes it more suitable for high-frequency applications where signal loss is a concern.

3. High Tg FR4: The tg refers to a higher glass transition temperature (Tg), which makes this type more resistant to thermal expansion and more stable at high temperatures.

4. High-Temperature FR4: It is specifically designed for use in high-temperature environments, and has a higher Tg and improved thermal stability.

FR4 Parameters:
There are also several parameters that are used to describe the properties of FR4 materials, including:

ParametersDetails in FR4
Dielectric Constant (k):●       Measure of the material’s ability to store electrical charge●       FR4 materials typically have a dielectric constant of around 4.5
Loss Tangent (tan δ):●       Measure of the material’s ability to dissipate electrical energy as heat●       Lower values are generally better for high-frequency applications
Glass Transition Temperature (Tg):●       Temperature at which the material transitions from a solid state to a rubber-like state●       FR4 materials with higher Tg values are more stable at high temperatures
Thermal Expansion Coefficient (CTE):●       Measure of the material’s expansion and contraction in response to changes in temperature●       FR4 PCB typically has a CTE of around 17 ppm/°C

Comparisons among ceramic PCB, FR4, and metal core PCB

FeaturesCeramic PCBFR4 PCBMetal core PCB
DefinitionMade using ceramic as the substrate materialMade using a type of composite material called FR4 (flame-retardant grade 4)Has a metal layer as the substrate material
Dielectric usedCeramic (an insulator with a high dielectric constant)Epoxy resin (an insulator with a moderate dielectric constant)Any insulator with a low dielectric constant
Reliability factorsHigh thermal conductivity and high-temperature resistanceGood mechanical strength and good electrical insulation propertiesHigh thermal conductivity and low weight
UsagePower electronics, automotive electronics, and military/aerospace electronicsConsumer electronics, industrial electronics, and medical devicesLED lighting, power electronics, and thermal management systems
CostMore expensive than FR4 and metal core PCBsMore affordable than ceramic PCBs, but more expensive than metal core PCBsMost affordable option among the three

Usage and applications of FR4 PCB

Application of FR4

  • Electrodes: Electrodes used for electrocardiography (ECG) or electroencephalography (EEG) can be made from FR4 PCB, as it has good electrical characteristics and thermal stability.
  • Electronic devices: The lightweight and low thermal conductivity make them suitable for use in electronic equipment such as computers, telephones, televisions, and other similar products.
  • Medical devices: FR4 PCB has excellent resistance to heat and flame exposure, which makes it an excellent material for medical devices such as pacemakers and defibrillators.

How is an FR4 PCB made?

How is Fr4 made

Step 1: PCB Design

Create a detailed layout of the board using computer-aided design software.

Step 2: Photolithography

Create a photomask of the circuit pattern and use it to transfer the design onto the PCB.

Step 3: Etching

Remove excess material from the PCB to create the desired circuit traces using a chemical etching process.

Step 4: PCB Drilling

Drill holes in the PCB for components using a computer-controlled drilling machine.

Step 5: Plating

Apply a thin layer of copper to the inside of the holes and to the surface of the PCB using electroplating.

Step 6: Soldering

Mount components onto the PCB using a soldering process.

Step 7: Testing

Verify that the board is functioning properly using specialized test equipment.

Step 8: Finishing

Prepare the PCB for use in a final product by adding protective coatings or installing connectors or other hardware.

Tips for selecting right FR4 materials

Tips for FR4 manufacturer

  • The FR4 material should be as thick as possible to ensure the best heat transfer.
  • It should have high thermal conductivity, which means that it will transfer heat quickly and efficiently.
  •  It should have good mechanical strength, which means it can withstand high temperatures without cracking or breaking.

How to select FR4 PCB manufacturers?

A good FR4 PCB manufacturer has the capability, experience, and standards to produce high-quality, accurate FR4 boards with low defects. This is where IBE fits well as it has been in PCB manufacturing since 2005. This China-based company would help you get the best FR4 PCBs to use for multiple purposes. Hence, a reliable manufacturer is way more important to find before investing in the product.

FAQ about FR4 PCB

An FR4 PCB is a PCB (printed circuit board) made of fiberglass-reinforced epoxy resin that acts as a fire retardant and makes the material resistant to heat and friction, making it ideal for use in high-end electronics.

  • Standard FR4
  • Low loss FR4
  • High Tg FR4
  • High-Temperature FR4
  • The FR4 material should be as thick as possible to ensure the best heat transfer.
  • It should have high thermal conductivity, which means that it will transfer heat quickly and efficiently.
  • It should have good mechanical strength, which means it can withstand high temperatures without cracking or breaking.

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