Types and Properties of FR4 TG

As the world’s technology advances, high FR4 TG PCBs are in high demand. With the help of electrical components, this PCB material can hold higher temperatures. This ensures that printed circuit boards remain in stable condition.

A PCB’s temperature area may occasionally experience heat levels over the recommended operating temperature. This extreme temperature causes PCBs to melt as a result of thermal expansion. Temperatures that are too high will cause expansion or contraction between PCB layers. On the other hand, the FR4 high TG PCB is the most effective alternative to conventional PCBs for removing all of these uncertainties.

If you want to learn more about FR4 TG PCB material, continue reading the article.

What Is FR4 TG?

A flame-retardant composite material used in printed circuit boards, consisting of glass fabric and epoxy resin. To combat a higher glass transition temperature, PCB boards have reinforcing material of the fourth grade. Similarly to printed circuit boards in electrical machines, this substrate’s relevance in PCBs is significant.

The abbreviation “FR” represents the materials fire retardant. Most PCB makers use FR4 because of its consistent physical and mechanical properties. Epoxy pigment board is used in FR-4 laminates to improve the reliability of circuit boards.  The Flammability Rating (UL94-V0) enables the use of FR4 TG PCB in several applications where incisive conditions may be present.

Types of FR4 TG PCB

According to temperature ranges from low to high and the number of copper layers, there are three main types of FR-4 PCB. The types are as follows:

  • Single-Sided PCB
  • Double-Sided PCB
  • Four or Multilayer PCB

Properties of FR4 TG PCB

The usage of high TG PCB materials is increasing in the worldwide electronics sector. These PCBs with high TG are helpful in communication devices, control panels, and computers.

The primary distinction here is the inexpensive costs. This is due to these FR4 PCBs with a high TG being more costly than standard TG PCBs. Moreover, these materials with a high TG possess the majority of essential features. These consist of the following:

· Flame Retardant

Flame retardants are chemicals used to treat materials to reduce the risk of a fire spreading through them. The excellent thermal, mechanical, and electrical qualities of FR4 substrates make them ideal for various electronic applications. FR laminates and prepregs may be used in various applications because they are versatile, flexible, and reliable in production.

· Good Electrical Properties

Signal integrity and impedance issues depend heavily on the electrical qualities of a PCB material. They determine how quickly an electrical signal passes through the material and how much electrical charge a particular volume can hold.

· Low Moisture Absorption

Moisture absorption refers to a PCB material’s resistance to water absorption when submerged in water. The weight increase brought on by water absorption in a circuit board material is expressed as a percentage increase when measured under controlled circumstances. When immersed in water for 24 hours, FR4 materials absorb moisture at a very low rate (0.10%).

What Are The Advantages Of FR4 TG?

· Low-Priced Materials

The material for FR-4 printed circuit boards is not only inexpensive but also easily accessible. Despite this, their operational quality is of an exceptionally high standard. On the other hand, the cost of a material with a high Glass Transition Temperature and a High Comparative Tracking Index is rather high.

· High Dielectric Strength

The High Dielectric strength of FR-4 material ranges between 4.25 and 4.55, depending on variables such as glass weave type, thickness, resin percentage, and copper foil roughness. An insulator’s or dielectric’s strength is the highest electric field it can withstand before failing as an insulator or conducting electricity. Therefore, selecting a material with a greater dielectric strength assures the insulator’s superior quality.

· Weight Bearing

FR-4 is a blend of Fiberglass and epoxy resin, so it offers the PCB a high load-bearing capability and mechanical strength. However, a material’s strength and load-bearing capacity is mostly determined by its thickness. The thickness of a typical FR-4 material can range anywhere from 0.2 to 3.2 m.

· Moisture Resistant

Humidity has no impact on the expansion and contraction of FR-4 printed circuit boards. The electrical, thermal, and resistance of the material to the formation of Conductive Anode Filament (CAF) when the circuit is turned on are all impacted by moisture absorption. Hence, FR-4’s great moisture resistance offers it an advantage as a base PC material and makes it suitable for usage in humid environments and maritime PCB applications.

· An Increased Glass Transition Temperature

With a TG of 150Tg or 170Tg, FR-4 is particularly resistant to high temperatures. TG represents the PCB’s glass transition temperature. The Glass Transition Temperature describes the temperature at which the PCB begins to soften and lose its form. This is why the TG value of PCB is so important. As more TG values are available, greater PCB performance may be guaranteed. In addition to influencing its heat resistance, PCB’s TG value also impacts its resistance to water and chemicals.

· Increased Decomposition Value

The decomposition temperature is the temperature at which approximately 5% of a PCB laminate’s mass is lost due to breakdown. The FR-4 PCB material has a higher temperature of breakdown, which is greater than 345 degrees Celsius. High decomposition temperatures provide better protection and increase PCB longevity.


FR-4 TG circuit boards are used in digital, analogue, and mixed-signal circuits operating at high speeds. This is because they transfer signals swiftly. The electrical circuits can work at temperatures up to 125°C without damage. The circuit boards can withstand temperatures up to 150°C. These temperatures make circuit boards appropriate for automotive, medical, and aerospace applications.

In order to protect the embedded electronic circuits in FR-4 TG circuit boards, they should only be used at temperatures below 100°C. They are also simple to produce because they require no further processing. The thermoset resin used to create FR-4 TG circuit boards is chemically heat-resistant and hence extremely brittle. The circuit board can work safely at temperatures as high as 150 °C. Highly recommended for usage in aerospace, medical, and automotive industries, FR-4 TG circuit boards are appropriate for cleaning with combustible chemicals.


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