With the rapid development of the electronics industry, especially electronic products, are developing towards high functionality and high multi-layers, which requires higher heat resistance of PCB substrate materials as an important guarantee.
The emergence and development of high-density mounting technologies represented by SMT (surface mount technology) and CMT have made PCB becomes inseparable from the high heat resistance capabilities in terms of small aperture, fine line, and thinning. That’s the reason why high Tg PCB becomes favored . In this article, we will discuss how high Tg PCB is manufactured and what materials should be used in high Tg PCB manufacturing.
What we can know about high Tg PCB?
Circuit boards generate heat when electricity passes through them. In order to allow circuit boards to keep functioning efficiently, it’s important for them to be heat resistant. High levels of heat from the circuit board and high ambience temperatures can cause circuit boards to fail. Therefore, it’s important for them to be heat resistant.
TG denotes resistance to heat in PCBs. The raw material used in the making of PCB determine how much heat can a circuit board tolerate before failing. This article is about all you need to know about high TG PCBs.
What materials can be employed in high Tg PCB?
The flame resistant material can be highly considered. Glass epoxy is one of the flame resistant materials. Thus, the polymers and composites made of or contained epoxy resins become the first choice for high Tg PCB manufacturing. Here are some materials as follow.
FR4: Glass fiber reinforced epoxy laminate. FR stands for flame retardant. FR4 material conforms to UL94V-0 standard flame retardant test. Even under both dry and wet condition, FR4 still have electrical resistance performance. Hence, FR4 can better copy with the heat dissipation came from dielectrics and conductors.
Here are some common ISOLA materials that are used to manufacture high Tg PCB.
IS410: As FR4 laminate and prepreg materials, it enables withstand 180℃ Tg. Besides, it can handle multiple thermal excursions and passed the 6X solder test at 288℃. For lead-free soldering, it can also adopt high tg PCB.
IS420: IS420 is a high performance multifunctional epoxy resin. Unlike common FR4 materials, it has better thermal properties and low expansion performance, which can blocks UV radiation and is compatible with AOI machine (automated optical inspection).
G200: G200 is a combination of epoxy resin and bismaleimide/triazine (BT). It is characterized with high heat resistance capabilities and good electrical properties.
Except the above materials, there also have other materials like S1000, ITEQ IT-180A, ARLON 85N that can also be selected for high tg PCB manufacturing.
What are properties of a high Tg PCB?
A high TG PCB will showcase the following properties and characteristics:
- They have high heat resistance and are suited for use in countries with hot and humid environments such as African nations, Latin America, South Asia, etc.
- High TG boards have a high level of thermal shock resistance. They can withstand exceptional levels of thermal stress without any faults or damages.
- High TG PCBs have low Z-axis CTE and high level of PTH reliability.
What are pros and cons of high Tg PCB?
Advantages
1.You’ll notice high level of stability from a PCB even during stressful operations.
2.You can print circuit designs with high power density on a PCB with high TG.
3.Such PCBs become an ideal choice for equipment with less room for air flow. Such environments have high ambience temperatures and high TG PCB can tolerate them.
Disadvantages
1.Their manufacturing is a bit complex and expensive since the manufacturer needs to include uncommon raw materials.
2.PCBs with high TG are not easily available in the local market. You’ll have to contact a supplier.
3.Buying low quantities will be really problematic since suppliers usually don’t sell retail quantities for a reasonable price.
Which areas can be used high TG PCB?
- Engine Controllers
Engines generate extreme heat and only a high TG PCB can be used to make an engine controller. Not only these PCBs can withstand heat, they can also function well in a long run. - Metal Processing Units
Machines that process metal such as cutting, molding, CNC, generate high heat levels, making a high TG PCB the suitable choice for making circuit boards for these machines. - Hot Cutting Machines
Machines that use hot cutting technique to cut plastic sacks and other fabric need a controller and circuit board that can operate under extreme stress. That’s where you can use high TG PCBs. - Super Computers
Super computers and severs run 24/7 without any scope of rest. Therefore, in order to ensure quality performance throughout the life of a server or a super computer, it’s safe to use a high TG PCB.
High TG Vs. FR4 TG
Below are some differences between these two terminologies:
- FR4 can be said to be a classification of high heat resistance board, used to make high heat tolerating circuit boards.
- TG can use materials such as polyimide, hydro-carbon, Teflon-based laminates, etc., while TF4 is a designation for epoxy material made out of glass reinforcement.
- TG has high temperature tolerance that can exceed 300 degrees Celsius, while TF4 has an average heat tolerance level of 140 degrees Celsius.
FR4 TG 150 Vs. FR4 TG 170
The numbers 150 and 170 denote ideal tolerable temperature in degrees Celsius. Any PCB marked as “FR4 TG 150” can withstand heat temperatures from 130 degrees Celsius to 150 degrees Celsius.
PCBs marked as “FR4 TG 170” have an ideal tolerable temperature range of 150 degrees Celsius to 170 degrees Celsius. Therefore, FR4 TG 170 is a superior version of FR4 TG 150.
What methods can be adopted to resolve heat dissipation in high Tg PCB?
While high TG PCBs can withstand high heat levels, it’s still mandatory to ensure efficient cooling to keep them functioning flawlessly. Below are some techniques that you can implement in your project to keep heat from escaping from the circuit board.
1.Use air cooling fan or liquid cooling system. If you’re using an air cooling system, consider high w/mk (watt per meter by Kelvin) thermal paste, high speed fan(s), and copper heatsink for best results.
2.If possible, always use copper heatsinks instead of aluminum and make sure that the heatsink has thick copper plates.
3.You can install multiple fans on the heatsink to discourage heat buildup on the circuit board. make sure that the air fans have open vents and that dust and dirt isn’t blocking the air flow.
4.Use thermal pastes with at least 79 w/mk.
5.Thermal via arrays is another technique, where the circuit boards are double-sided or multilayered. This intelligent PCB technique is designed to encourage efficient heat conduction.
6.Place a copper coin right under the component that generates a lot of heat. Such implementation will help conduct heat off that component, keeping the entire circuit board cool.
How to select a high Tg PCB manufacturer?
High Tg PCB plays an essential role in some complex electronics, so choose the right PCB manufacturer becomes priority when we start a high Tg manufacturing project.
- Ask the manufacturer what raw materials they’ll use in the circuit board manufacturing. That’ll give you an idea of how much heat your circuit board will be able to tolerate.
- Choose a manufacturer that offers warranty or replacements for faulty products. In order to avoid inconvenience, try going with a maker with a good reputation in the market.
- Always go with an honest maker. Choose a seller who is honest with their marketing and tells you all the pros and cons of their product.
- Never go with a manufacturer, who tries to overcharge money for shipping, taxation, or additional expenses. Always have a clear note of expenses, ask for a cost breakdown, and double-check on your end if the manufacturer is charging you correctly.
- Always go with a manufacturer such as IBE Electronics, who is easy to reach.
IBE: Your choice for PCB manufacturing
Now that you’ve got an idea of high TG PCBs and have understood a quick criterion of selecting a circuit board manufacturer, the next thing to do is to find good PCB makers on the internet.
IBE has extensive expertise in PCB manufacturing and assembling. If you need printed circuit board fabrication or assembly, please get in touch with our PCB experts and we will be happy to assist you.
The heat required for the PREPREG rigidity must be applied without exceeding the FR4 Tg to preserve the PCB stability. The standard FR4 Tg is between 130 – 140°C, the median Tg is 150 °C and the high Tg is greater than 170°C.
Generally, there are 3 level of high Tg PCB : standard Tg (above 130℃), mid Tg (above 150℃), high Tg (above 170℃). For the working condition temperature aspect, high Tg PCB can well handle such extreme condition. And some other heat resistant materials can also be considered.
Glass transition temperatures of cyclic and linear PS were determined by DSC. For linear PS, the dependence of Tg on molar mass can be expressed by Tg = [1/Tg + K/Mw]−1, where K is a polymer-dependent constant and Mw is the weight average molar mass.
