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
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.