High Tg PCB

High Tg PCB

If you work with printed circuit boards in your life, you may or may not be familiar with the High Tg PCB. Since the effective operation of your printed circuit boards is so important to your business, it may be beneficial to understand a little bit more about high Tg printed circuit boards. With the development of high-temperature electronics technology, there is a great demand on boards with high Tg. And Tg is one of the most important properties of any epoxy and is the temperature region where the base material (polymer or glass) changes from a solid, rigid, and glassy state to a rubbery state. Every PCB has a different Tg value based on its substrate. And PCB will start to change its state which will make a bad effect on PCB fabrication if the operating temperature of PCB exceeds its normal Tg value. High Tg circuit boards have better stability at high temperatures because the substrate provides better heat resistance, temperature point, mechanical property, electrical properties, feature capability material, and chemical stability for the board.

What is High Tg PCB?

High Tg is another name for a high-temperature PCB, meaning printed circuit boards designed to stand up to high-temperature extremes. A circuit board is defined as high Tg if its glass polymer transitions temperature (Tg) is higher than 150 degrees Celsius. FR-4 High Tg PCBs contain PCB material for high-temperature situations so you can count on them even under extreme temperature conditions.

What is FR4?

FR4 is the code name designated for a grade of flame-retardant fiberglass reinforced epoxy material; hence FR4 PCB gives an as much higher level of resistance to heat than ordinary PCB. FR4 circuit boards are classified into four divisions and are determined by the number of copper trace layers that are found in the material. They include;

  •  The single-layer PCB or single-sided PCB
  •  Double-sided PCB or Double-layer PCB
  •  Four or more than ten layers of PCB or Multilayer PCB

When do you need a High-temperature PCB?

You need a high-temperature circuit board for your applications if your PCB will be experiencing a thermal load no greater than 25 degrees Celsius below the Tg. If your product will be operating in the 130-degree Celsius range or higher, you will want to use a high Tg PCB to be safe.  The main reason for the high Tg PCB is the movement to RoHS PCBs.  It is causing most of the printed circuit board industry to move toward high Tg materials because of the higher temperatures needed for the lead-free solder to flow.

Properties of high Tg PCB

 With the rapid development of the electronics industry, so high Tg PCBs material is widely used in computers, communication equipment, precise apparatus as well as instruments, and so on. Toward the high functionality, high multi-layer development, PCB substrate material needs higher heat resistance as a prerequisite. And the boards are more and more inseparable from the high heat resistance of substrates in the case of thinning, small aperture, fine wiring because of the emergence and development of high-density mounting technology represented by SMT and CMT.

So the difference between general FR-4 and high FR4-Tg is that the mechanical strength, adhesion, water absorption, dimensional stability, thermal decomposition in the hot state, especially after water absorption, which are differences in various conditions such as thermal expansion, and it is obvious that high TG PCB is better than ordinary PCB substrate materials. So there is a great demand for high Tg PCB in recent years, but the price is higher than ordinary PCB. High Tg material is also popular in the LED lighting industry because heat dissipation of LED is higher than normal electronic components, but the same structure of the FR-4 board is much cheaper than metal core PCB, such as aluminum PCB.

High Tg materials have the following properties:

·       Resistance to high temperatures

·       Long delamination durability (aging of materials to consider for safety reasons)

·       Low thermal expansion

·       Excellent PTH reliability

·       Good mechanical properties

·       High-temperature durability

·       The high value of thermal stress resistance

Advantages of High Tg PCB:

Withstand High Power Density Designs:

 If a device has a high power density with a very high heat generation rate then High Tg PCB is a good solution for heat management. Reduction in the heat generation of a regular PCB can be accomplished by using a larger PCB, changing the design and power requirements of a device. Alternatively, a high Tg PCB board can be used.

Ideal for Multilayer & HDI PCBs: 

Multilayer & HDI PCBs are more compact and have very dense circuits which can result in high levels of heat dissipation. High Tg boards are often used in these kinds of PCBs to ensure reliability during operation.

Higher Stability in working temperature: 

If the Tg of a PCB substrate is increased then it will automatically increase the heat resistance, moisture resistance, chemical resistance, and stability of the device.

Applications of High-Tg PCBs:

The High-Tg PCBs applications vary amongst various industries. Some of them are listed below:

Metal industries:

Getting a proper metal shape requires cutting, grinding, welding, and melting a metal piece. The temperature change in this process varies to a great extent. So, to keep the microcontroller of these machines flawless, High-Tg PCBs are required.

Engine controllers:

Whether it is the aerospace or automobile industry, both industries require reliable controllers to improve the engine’s efficiency. With greater RPM and longer running hours, the temperature of the unit rises significantly. So, the use of High-Tg PCB becomes necessary to withstand higher temperatures.


High Tg PCB will be very important when you are looking to protect your printed circuit boards from the high temperatures of your application’s process or during the extreme temperatures of lead-free assembly, but you will naturally want to consider multiple methods of drawing the extreme heat generated by electronic applications away from your board.

There are three considerations for dissipating the high heat generated by the action of electronics with printed circuit boards: convection, conduction, and radiation. Convection heat transfer is the process of transferring heat to air or water to allow it to flow away from an area — for example, when fluid absorbs heat and flows to a heat sink where it cools. Convection can also refer to the use of a fan or pump to force air over the surface, drawing heat away with it. In most printed circuit boards, you will find a convection system where convection, usually including a cooling air fan, bears the heat through thermal vias to large, emissive heat sinks connected to conductive backings. Conduction heat cools by putting the heat sink in direct contact with the heat source, allowing the heat to flow away from the source much like an electrical current flows through a system.

Designers dissipate radiation heat by making sure to design a direct path for electromagnetic waves to flow away from the source. Although electromagnetic wave radiation does not generate a tremendous amount of heat if the board is designed to put reflective surfaces in the path of these waves, it can cause a rebound effect and significantly magnify the amount of heat that radiation generates on the board.

You can see that the more heat you need to deal with, the more it affects the design of the board. Reducing power density can limit the effectiveness of your product while adding heat sinks and fans can increase size, weight, and cost. This is why even if you are aware of other effective methods of heat management, it can be a very good idea to look into high Tg materials as part of your overall heat control solution.

Characteristics of high TG PCB material

  • It has a high resistance to heat
  • Lower Z-axis CTE.
  • Excellent thermal stress resistance
  • Excellent PTH reliability
  • High thermal shock resistance

Some Other Applications of High-TG PCB:

The high TG PCB board has various uses in well-known areas, some of which include;

  •  Automotive equipment
  •  Computers
  • Consumer equipment
  •  Industrial equipment
  • Communication equipment

Materials used for high- TG PCBs manufacturing

  • FR4 S1141
  • FR4 S100
  •  IT180
  • Rogers 435OB

Why EuropePCB is the top priority for Hight Tg PCBs?

Finally, EuropePCB is now a non-stop and positive force in PCBA manufacturing for complete PCB assembly services since 2006. As the EMS world is rapidly changing, EuropePCB has redefined itself permanently to provide nothing but superior production services. MOKO technology PCB assembly satisfies and exceeds its customer’s expectations. In terms of price, quality, and delivery. If you are looking to get the best-embedded systems or a high TG PCB manufacturer, look no further. You can use EuropePCB to design your high TG PCB boards.

Regardless of the complex nature and scope of specific PCB applications, EuropePCB has the technical expertise and the best High TG PCB materials to develop a customized Printed Circuit Board (PCB) that would satisfy your particular demands.


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