Sep 29, 2021|Product Innovations and Design, Technological Advancements and Materials

What Is a High TG PCB?

A high TG (Glass Transition Temperature) PCB is a Printed Circuit Board (PCB) with TG equal to or greater than 170°C, which is the threshold for what is considered ‘high.’ Therefore, this is a PCB that is designed to withstand high temperatures.

What Is FR4?

FR4 is epoxy material reinforced with flame retardant fiberglass. FR4 with a high TG enhances the heat resistance of ordinary PCB. There are three classifications of FR4 circuit boards that are based on the number of copper traced layers in the material:

  • Single-sided PCB
  • Double-sided PCB
  • Multilayer PCB

What Is TG?

TG is the mechanical property that designates a transition temperature to each polymer or glass (base material) at which the material changes from a glassy, solid-state to a rubbery state. Materials that exceed their TG do not ‘melt.’ Instead, they become rubbery through undergoing structural change. The Glass Transition Temperature (TG) is one of the most important qualities of epoxy. The characteristics of high TG materials include:

  • Long delamination durability
  • Low thermal expansion
  • Resistance to high temperature

Characteristics of High TG PCB Material

The following are the main characteristics of high TG PCB materials:

  • High heat resistance
  • High PTH reliability
  • Low Z-axis CTE
  • High thermal shock resistance
  • Exceptional thermal stress resistance

Although high TG PCBs have all these advantages, it is important to correctly take care of your PCB. One thing most people forget to do is to find safe ways to keep it cool. Yes, even a high TG PCB needs to have adequate heat dissipation to avoid getting damaged easily. The good thing is that a basic understanding of how heat is transferred is enough. Most machines are built-in ways to make it easy.

Some ways heat is dissipated your high TG PCB include:

  • Conduction
  • Radiation
  • Convection

By placing the device in well-aerated areas and following safety instructions, you can improve the lifespan of your high TG PCB by dissipating all the heat that you can naturally and thus not overworking it.

High TG PCB Application

The high TG PCB is an important, versatile device used in many common applications and devices. The most common devices to find them in are those that generate extreme temperatures, contain highly reactive chemicals, and produce a lot of vibration and shock when operated:

  • Computer hardware
  • Missiles and jets
  • Telecommunications
  • Automotive equipment
  • Industrial equipment
  • Airplane and automobile engines

High TG PCBs are found primarily in devices and machines that create harsh environments within their internal structure when operated.

Materials Used for High TG PCB Manufacturing

The most common material used for TG PCB manufacturing by a PCB manufacturer are:

  • Isola 370HR
  • Ventec VT47
  • IT180
  • Panasonic R1755V/R1650V
  • Kingboard KB6167

Advantages of High TG PCBs

Why should we use high TG PCBs on our devices then? What exactly are the long-term, short-term, and financial benefits?

Higher Stability

Due to high TG PCBs’ mechanical resistance to high heat, corrosive chemicals, and moisture, they help stabilize the conditions within a device. Internal changes due to processes will affect the hardware less when you use high TG PCBs. The lifespan of the PCB board is also increased because high TG PCBs reduce short-circuiting and other common PCB failures.

Bear High Power Density Designs

High power density designs generate high temperatures and need to have structures that can withstand and dissipate the energy.

Ideal for Multilayer & HDI PCBs

Multilayer and HDI PCBs have compact, dense circuits that minimize the circulation of air and hence generate more heat. This can be problematic for the functionality of the device and the integrity of the hardware. High TG PCBs are therefore the most ideal for multilayer boards and HDI PCBs.

When Do You Need a High TG PCB?

For printed circuit boards that cannot bear a thermal load more than 25°C below the TG, then it would be advisable to get a high TG PCB to replace it. If your device functions in the 130°C range or higher then you should also consider getting a high TG PCB for it.

An important thing to note is the technological migration to RoHS PCB. RoHS PCBs are lead-free solders that need higher temperatures to flow. Only high TG materials can handle them. This migration will make it necessary to use high TG PCBs.

Applications of High TG PCBs

As mentioned earlier, high TG PCBs can be found in numerous industries, but how they are used in each industry is unique:

Metal Industries

Metal processing involves a combination of many processes, and one primary example is shaping the metal to a form that can be used for whatever purpose. The process of cutting involves cutting, grinding, welding, and melting, and these are all vastly varying temperature changes. The fluctuations in temperature destabilize the microcontrollers in the machines, and the only way to keep them steady is to use high TG PCBs.

Engine Controllers

An engine’s efficiency is dependent on how reliable its controllers are. High TG PCBs are necessary to withstand the higher temperatures generated with greater RPM and longer running hours.

Other applications of High TG PCBs

High TG PCBs can also be found in:

  • WiFi Boosters
  • Embedded computer systems
  • Low-cost PLC in contract manufacturing services
  • RFID gateways.


High TG PCBs have an array of applications, from engines to industrial processes, WiFi boosters, and computer systems. They mitigate the internal damage a machine does to itself when it functions by raising the tolerance of a device to heat, moisture, and chemical corrosion. Not only do they improve functionality, but they also enhance the lifespan of PCBs in general by reducing common issues like short-circuiting.

This moderation of internal conditions makes devices and machines less faulty and thus safer. High TG PCBs have also allowed safer innovation with PCBs by reducing the heat generated by multilayer PCBs. Although high TG PCBs are great, you need to make sure you have the best quality PCBs and professional advice to get the best out of them.

Author Profile

Sunny Patel
Sunny Patel is the Engineering and Sales Manager at Candor Industries. Sunny is trained as a IPC-A-600 trainer, AS9100 Lead auditor, IPC CID and got his Engineering degree at the University of Toronto.