PCB FR-4: the Guide to fr-4 for your Printed Circuits

Hello readers welcome to the new post. In this tutorial, we will have a look at PCB FR-4. There are different types of materials used to make PCB boards but the most commonly used is FR4. In this post, we will cover the details of FR-4, its features, and related parameters. So let’s get started with an introduction to PCB FR-4

 Introduction to PCB FR-4

• PCBs, or printed circuit boards,  are the main part of electronic component devices and products.It is used in many types of electronic devices and projects. It has many types such as single, side, double layer, and multiple layers and each comes with its own features.

 What is FR-4?

• The FR4 is a commonly used dielectric material in PCB boards. it is based on materials parted copper layers in boards and offers mechanical support to boards.
• It is NEMA standard for glass-reinforced epoxy laminate material. This material is has a composite nature and made using fiberglass and epoxy resin.

FR4 PCB Material

The FR4 PCB materials are good insulators that do not expand or contract. Flame resistant 4 used to make differnt products and projects.  it is used in electronic circuits for computers and phones to automotive electronic parts.

FR4 PCB materials are the best insulator to help devices to be humid and dry. FR4 material is glass laminate made for board specially.

In PCB design or PCB prototype substrate is a comonly used substrate material for PCBs since offers good heat, flame, and electrical insulation features.

FR4 PCB comes with good features and is used in the PCB industry. It has a low coefficient of theraml expansions and does not contract or expand for different temperature values.

FR4 Dielectric Constant

• FR4 materials come with the value of dielectric constant between 3.8 to 4.8 according to glass weaving style, thickness, and resing constant.

 Properties of FR-4

Flame Retardant

Excellent Electrical Properties

The FR4 used base materials that is based on its electrical features of good type. The electrical features of PCB materials are best for signal quality improvement, insulation, and impedance control.

Some electrical properties of FR4 materials are listed here

• High Glass Transition Temperature: 150Tg-170Tg
• Decomposition Temperature=>345 ℃
• Low Co-efficient of Thermal Expansion=2.5%-3.8%
• Dielectric Constant = 4.25-4.55
• Dissipation Factor =0.016

FR-4 Manufacturing Process

Read more Applications of Multilayer PCB

Epoxy resin is used for the impregnation of fiberglass sheets. These sheets are used to make FR4. Eight reinforced sheets were used covered with a copper foil layer. This structure is configured in press and that makes a single FR 4 sheet as a combination.

Materials for FR-4 Fabrication

The glass that exists in the FR4 sheet makes it a strong material. The epoxy resing used normally used flame retardant. Bromie used to provdies the flame retardant features. It makes PCb a flame-resistant material. it also helps to board high temperatures.

Copper used helps to etch patterns on board. These etching patterns make basic circuits that make connections between components. it also makes connections of interconnects of circuits.

Interconnections make connections of layers on boards. In FR4 hardened epoxy is used as Dicyandiamide. It comes with high temperature of 300 degrees.

FR4 is part of multiyear boards with single layers for component connections.

Types of FR-4

Standard FR-4

This type of FR4 is called normal material that hs heat resistance from 150-160 Celsius.

High TG FR-4

High TF FR4 means high glass transition temperature. PCB board created with high glass transition temperature FR4 materials comes with features to resist and sustain structure for 170 degrees. This material’s high TG value is obtained through a good lamination process.

PCB created with these materials has features to high resistance and maintains structure at 170 degrees.

The standard FR4 is the best insulator and flame retardant but comes with limitations for high power voltage or heat.

 High TG FR-4 Material Uses

• It is part of electrical and electronic devices and projects.
• it is used in computer motherboard creation.
• it is also part of communication devices

High CTI FR-4

The CTI or Comparative Tracking Index is the limit for which FR4 can handle undesired current passing over the board traces. The value of CTI helps to define how much resistance board materials show for different electrical conditions like moisture and leakage on board.

The high value of CTI material is about 600 which helps the material resist and handle the harsh conditions

High CTI FR4 material used in marine applications and aircraft

FR-4 with no laminated Copper

This FR4 is different in its functions. According to its name this material did not have copper lamination and some used as insulation and board support

 Applications of FR-4

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• There are different applications of FR4 explained here
• It is part of Consumer Electronics
• it is part of the Aerospace and defense systems
• Automotive electronics
• It used in Industrial control systems
• It is used in different Telecommunications equipment

 Advantages and Disadvantages of FR-4 Materials PCB?

Advantages

1. FR4 PCB board is commonly used and has a low cost. They offer good quality operation. However, the cost of high glass transition temperature and high comparative tracking index is high.
2. This material comes with a high dielectric strength of about 4.25-4.55 according to different parameters like glass weave style, resin content, thickness, and copper foil roughness. The dielectric strength explains the highest electrical field that dielectric materials show resistance without breaking or changing into conductive materials.
3. FR4 is a mixture of fiberglass and epoxy resin and offers high load-bearing features and mechanical strength to the board.  The thickness of standard FR4 is about 0.2 to 3.2m.
4. FR4 offers good moisture resistance features. Humidity does not have an affect on the FR4 board like contracting and expansion. But moisture absorption affects the electrical and thermal features of the material and also the power of materials to handle conductive andoe filament creation during power connection. So high value of moisture resistance has advantages to FR4 uses as base PCB materials and supported board in marine uses
5. FR4 is a high-temperature resistance material and has a value of TG about 150Tg. The Tg is the glass transition temperature of PCB. Glass transition is the temperature where the board starts to become softened and affects its structure.  So high TG boards are important.
6. They have a high decomposition value which means the temperature where board about five percent of the laminate mass is lost due to decomposition. FR4 board material has a good decomposition temperature of >345 Celsius. The high decomposition temperature provdies good protection to the board for long-life working

Disadvantages

• The main drawback of FR4 is its high cost. The materials used for FR4 are high cost which makes the overall product high cost.
• Working with these materials is difficult. It is a hard material and that causes problems during cutting. So not easily configured on devices and projects.
• These materials are limited in flexibility. It is rigid materials that make it difficult to bend. It can be difficult to design devices that need high flexibility.
• FR4 is a hazardous material and has a toxic nature and can affect the environment if not accurately disposed of

Limitations of FR-4

• It does not have features to handle high temperatures due to low thermal conductivity.
•  It does not work well for high-frequency projects.
• Its dissipation factor is high which causes signal losses.
• It does not support controlled impedance
• It has a varying dielectric constant than other substrate materials.

Why Choose FR4 PCB?

Low Cost:

• FR4 board materials prices are lower than other materials like metal substrate. It makes the best option for different board types simple designs complicated, and multiple boards.

Mechanical Strength:

• The FR4board is strong and can handle high components. So it is used in harsh conditions

Moisture Resistant:

• FR4 board has resistance to moisture with a non-zero absorption rate. So they are used in humid conditions.

Flame Retardant: 

It has a high flammability rate of about UL94-V0 and the FR4 board does not increase fire make safe materials.

Read also:

• What is Ball Grid Array (BGA) on a PCB Board
• Introduction to PCB Boards Inks, Types, Uses, & Applications
• Main Parts of PCB Board
• Types of PCB Board
• Difference between Double sided and Multilayer PCB Board
• Double Sided PCB Board, Construction, Working, Types & Applications