As world technology is growing, high FR4 Tg PCBs are in high demand. Because this PCB material is used to resist the electronic components’ higher temperatures. That keeps printed circuit boards in a solid-state.
Sometimes temperature region of a PCB gets more heat than the standard operating temperature. That excessive temperature results in a meltdown of PCBs due to thermal expansion.
Excessive temperature will lead to expansion or contraction between multiple layers of PCB. But the FR4 high Tg PCB is the best alternative to other PCBs to remove all these uncertainties.
If you want to know a better understanding of Tg FR4 PCB material keep reading the article.
What Is FR4?
A composite material class of glass fabric and epoxy resin flame retardant used in printed circuit boards.
The 4th-grade reinforcing material is used in PCB boards to resist a higher glass transition temperature. The importance of this substrate in PCB is important, just like printed circuit boards in electrical machines.
The term “FR” denotes the fire retardant material. Most PCBs manufacturers use FR4 due to its important consistent physical and mechanical properties.
FR-4 laminates are epoxy pigment board material used to enhance circuit board integrity. The Flammability Rating (UL94-V0) makes FR4 PCB suitable in many applications where corrosive environments may be present.
Types Of FR4 PCB
There are three main types of FR-4 PCB depending on low and high temperatures and copper layers. The types are given as follows:
- Single-Sided PCB
- Double-Sided PCB
- Four Or Multilayer PCB
Why Glass Transition Temperature “TG” Is Important?
The term “Tg” refers to the glass transition temperature at which the PCB board will start to turn its body state from solid to flexible.
Manufacturers normally keep the Tg value higher than the operating temperature. For example, if the operating temperature of FR-4 Tg PCB substrate is 110ºC, then the Tg value should be at least 20ºC-30ºC higher.
Does Maximum Temperature Of FR4 TG PCB Matters?
The most impotant thing is maximum temperature of a FR4 PCB because good quality printed circuit boards
PCB materials change their physical properties at a certain temperature when exposed to extreme heat. The highly designates glass transition temperature or Tg value of FR4 PCB is 130 ºC.
You can call it a transition stage of a glass material into a soft material. When an FR4 printed circuit board exceeds a high temperature of 130 ºC, it compromises the body’s solid state into a flexible state.
The flexible or liquid state can highly affect the PCB substrate to change its form and cause low working efficiency. The electrical supply of PCB will also disturb the above operating temperature.
What Are High TG PCBs Or TG Value?
Glass fabric is the base material used in different layers while manufacturing a high Tg PCB. The Tg value is divided into three different temperature ranges, which are given as follows:
- Normal Tg PCBs temperature of FR-4 is 130ºC-140ºC
- Medium Tg PCBs temperature of FR-4 is 150ºC-160ºC
- High Tg PCB temperature of FR-4 is more than 170ºC
Is FR4 Higher PCB TG Better?
So now you have got the Fr-4 Tg temperatures range. The base materials’ glassy state or solid state will eventually change into a rubbery state when the temperatures cross the range given above. The rapid development of thermal expansion in the hot state region causes losing PCB mechanical strength.
The moisture-absorbing ability of high Tg PCBs at a higher temperature shows better reliability and mechanical efficiency than a medium Tg PCB.
The above temperatures conclude that if the FR-4 Tg value is higher, the mechanical and electrical properties would be much better. High Tg PCB substrate is highly compatible with the lead-free processes.
FR4 High TG PCB Properties
High Tg PCB materials usage is getting higher in the electronics industry worldwide. These high Tg PCBs are used in computers, control panels, and communication equipment.
The main difference is high prices because FR-4 high Tg PCBs are much more costly than normal Tg PCBs. FR-4 PCB high Tg materials have several most important properties, which are given as follows:
- Better Water Absorption And Moisture Resistance
- Thermal Decomposition while in a hot condition
- Adhesion
- Better Mechanical property and strength
- Stability in dimensions
- Chemical Resistance
- Higher heat resistance
- Better resistance to thermal stress
- Lower thermal expansion coefficient (CTE) at Z-Axis
- Longer PCB laminates durability (Materials aging factor)
- Efficient And Reliable PTH (Plated Through Hole Technology)
Advantages Of FR4 Tg PCB
The FR-4 glass transition temperature advantages are what you might be looking for the most in this article. So let’s kick in to find out what benefits you can get from these types of high Tg PCBs.
- Ideal Option For HDI And Multilayer PCBs
FR4 High Tg PCBs have dense and compact circuits. A higher heat dissipation level will observe in HDI and multilayer FR-4 high Tg PCBs components. These properties ensure a reliable and efficient higher Tg PCBs fabrication.
- Better Stability
High Tg PCBs have better moisture and heat resistance. Due to congested space, the placement of a normal PCB is dangerous and can cause a meltdown due to higher temperature production.
So you can avoid these extreme conditions by using a high Tg PCB substrate. Better chemical resistance ensures circuit board safety. Depending on the substrate, each PCB material has various Tg values.
The higher the Tg value, the more flexibility, and tensile strength the epoxy has. The lower the Tg value, the fewer welding and coating defects.
- Allow High Power Density Designs
If you talk about heat management in high heat-generating devices, then FR4 High Tg PCB is the most recommended option. The heat generation can be lower by using large circuit boards.
Why FR4 High TG PCB Material Is More Preferable?
The world health organization is encouraged to increase pollution-free electronic waste. Similarly, the PCB industries are aiming to manufacture high Tg PCBs.
That is because a higher Tg PCB prototype has a lead-free composition which is the main factor in reducing E-waste pollution. High Tg material allows the components to stay in place without needing extra adhesives.
It makes high Tg PCB ideal for applications with a possibility of de-soldering or where the precise apparatus must be in place with accurate alignment. High Tg PCBs are generally used in sensor, motor, and motion control applications.
Why Are Halogen-Free Base Materials Preferable In PCB?
Halogen-Free Base Materials are preferred in PCB as they have better resistance to water and acids. They are less hygroscopic and therefore do not absorb humidity quickly, increasing electronic components’ life span.
As a flame retardant, Halogen-free materials use Nitrogen, ATH, and Phosphorous. Halogen-free base materials are extremely resistant to high temperatures and have a high-temperature coefficient of resistance (RTH).
Halogen-free base materials have better adhesion and electrical and mechanical properties than their halogenated counterparts.
Applications Of FR4 PCB Material
High Tg PCBs are the best solution where more heat generation expects from a higher power density electronic product. FR4 PCB material has multiple applications, some of which are given as follows:
- Engine Control Pannels
- Metal Industry
- Computer Electronics Industry
Effects Of Excess Heat On PCBs
While PCB production, SMT (surface mount technology) can cause failure if the heat exceeds the glass transition point. The circuit’s creation due to high temperature can cause a higher spacing of BGA pads than it should be.
The circuit board connections and pads face cracks due to heat expansion. These cracks may not visualize after circuit tests of a PCB prototype.
But it can be seen during the final heating process or even worse when the final product is sent to the buyer and faces the PCB electrical properties failure.
But the manufacturers can reduce these defects if they use FR4 High Tg PCB epoxy laminate base material. That PCB board can work even on the highest temperature generation.
Heat Extraction Methods
There are three commonly used methods in heat removal from electronic devices convection, conduction, and radiation. Mostly two methods are used in electronic devices except for radiation. These methods are given as follows:
You can see heat sinks in most desktop PCs and other electronic devices attached to PCB boards. These heat sinks are used to remove heat from the source point directly.
The other and most common method is convection, in which air or liquid cools down the PCB. It helps to keep PCBs in a rigid state despite a high temperature.
There are two main types of convection methods forced and free. The forced method is acquired through fans installed on a PCB board.
A pump also extracts the fluid by moving through the heat source points where the liquid absorbs heat, just like a car engine. The other phenomena are done through a natural process.
Final Thoughts On FR4 Tg PCBs
During the designing stage, the Tg is the main feature to consider while identifying PCBs. It is important to choose the material based on the usage, either the high temperature or low working temperature requirements.
High Tg PCBs are the better option when high temperatures are expected. The substrate that a high Tg PCB material provides has higher temperature resistance and better chemical and mechanical stability on the PCB board.
So it is better to use high Tg PCB where high-temperature applications have more safety reasons.
