The Prevalence of Mid-High TG Materials in Multilayer PCB Fabrication

Author : Meidear

Update time : 2025-07-17 12:11:27

In the manufacturing of multilayer printed circuit boards (PCBs), mid-high glass transition temperature (TG) materials have become the norm. This article aims to explore the reasons behind this industry preference.

1. What is the TG Value?
TG represents the temperature at which a non-crystalline polymer, such as the epoxy resin in PCB substrates, transitions from a rigid glassy state to a more flexible rubbery state. In simpler terms, it is the critical temperature at which the substrate begins to lose its rigidity and dimensional stability. The TG value is a crucial parameter that directly impacts the performance and reliability of PCBs.

According to the different Tg values, PCBs can be divided into the following categories:
Low Tg PCB:
The substrate material is usually Tg≥125℃, suitable for low-temperature applications or scenarios with low thermal stability requirements.

Medium Tg PCB:
Its Tg value is generally between 150 °C and 180 °C, which can provide good performance and reliability within a certain temperature range.

High Tg PCB:
Using substrate materials with high Tg values, typically exceeding 180 ° C, it is suitable for applications that require long-term operation in high temperature environments or withstand high power.

2. Requirements of Multilayer PCB Applications
Multilayer PCBs are widely used in various high-tech fields, including communication equipment, medical devices, automotive electronics, and aerospace. These applications demand high levels of performance and reliability. For example, in automotive electronics, PCBs must withstand extreme temperatures, vibrations, and humidity. In aerospace, the reliability of PCBs is of utmost importance to ensure the safety of aircraft.

Ordinary PCBs with low TG values may experience problems such as deformation, delamination, and a significant drop in mechanical and electrical properties when exposed to high temperatures. This can lead to shortened product lifetimes and increased failure rates. In contrast, mid-high TG materials offer enhanced stability and resistance to environmental factors, making them better suited for these demanding applications.

Therefore, the production of multi-layer PCB should use at least TG150 or higher board materials to ensure that the circuit board is less affected by external factors during application and to extend the product's service life.

3. Advantages of Mid-High TG Materials
3.1 High Heat Resistance
One of the primary advantages of mid-high TG materials is their excellent heat resistance. During the manufacturing process, PCBs are subjected to high temperatures, such as in soldering and reflow processes. High TG materials can better withstand these temperatures, reducing the risk of pad floating, solder joint failures, and other heat-related issues. In infrared heat fusion and thermal shock tests, mid-high TG PCBs show significantly better performance compared to those made with low TG materials.

3.2 Low Coefficient of Thermal Expansion (CTE)
Mid-high TG materials typically have a lower coefficient of thermal expansion. This means that they expand and contract less in response to temperature changes. In multilayer PCBs, especially those with eight or more layers, a low CTE is crucial to prevent warping and reduce the risk of copper trace breakage at the corners of vias. By minimizing thermal expansion, mid-high TG materials help maintain the integrity of the PCB structure and improve its long-term reliability.

3.3 Chemical Resistance
Multilayer PCBs often undergo various chemical treatments during the manufacturing process, such as etching and plating. Mid-high TG materials exhibit excellent chemical resistance, allowing them to maintain their mechanical and electrical properties even when exposed to harsh chemicals. This ensures that the PCB retains its functionality and reliability throughout its lifecycle.

3.4 Dimensional Stability
The higher TG value of mid-high TG materials provides better dimensional stability. This is particularly important in applications where precise alignment of components and traces is required. With improved dimensional stability, PCBs can be designed with smaller feature sizes and higher component densities, enabling the development of more compact and high-performance electronic devices.

In general, PCB made from medium to high TG boards have better quality, performance, and reliability than low TG boards.

4. Meeting Industry Standards and Regulations
In addition to the performance advantages, the use of mid-high TG materials in multilayer PCB manufacturing also helps meet industry standards and regulations. For example, in the electronics industry, there is an increasing demand for products that are environmentally friendly and compliant with regulations such as RoHS (Restriction of Hazardous Substances). High-temperature processes, such as lead-free soldering, are often required to meet these regulations. Mid-high TG materials are better equipped to handle these high-temperature processes without sacrificing performance.

5. Cost Considerations
While mid-high TG materials may have a higher initial cost compared to low TG materials, the overall cost of using them in multilayer PCB manufacturing can be justified by their improved performance and reliability. The reduced risk of product failures and the need for rework or replacement can result in significant cost savings over the long term. Additionally, as the demand for high-performance electronics continues to grow, the economies of scale are helping to drive down the cost of mid-high TG materials.

In conclusion, the use of mid-high TG materials in multilayer PCB manufacturing is essential to meet the stringent requirements of modern high-tech applications. Their superior heat resistance, low CTE, chemical resistance, and dimensional stability make them the material of choice for producing reliable and high-performance PCBs. As the electronics industry continues to evolve, the demand for mid-high TG materials is expected to increase further, driving innovation and improvements in PCB manufacturing technology.

Brands and Models of High-TG PCB Materials?
In the realm of multilayer PCB manufacturing, the choice of high-TG materials is crucial. Here are some well - known brands and their representative high - TG material models.

1. Isola FR408HR
Isola is a globally recognized leader in the PCB material industry. The FR408HR is a high - performance, high - TG epoxy - glass laminate. With a glass transition temperature typically around 170°C or higher, it offers excellent heat resistance. This makes it suitable for applications that involve high - temperature soldering processes, such as lead - free soldering which has become a standard in the industry due to environmental regulations. In addition to its high heat resistance, the FR408HR also has a low coefficient of thermal expansion (CTE), ensuring dimensional stability even when exposed to thermal cycling. This property is especially important for multilayer PCBs where precise alignment of layers is critical. It also shows good chemical resistance, which is beneficial during the PCB manufacturing process that involves various chemical treatments like etching and plating.

2. Rogers^TM Series (e.g., RO4350B)
Rogers is renowned for its high - frequency and high - performance PCB materials. The RO4350B from the RO4000? series is a popular choice. It has a relatively high TG value, which, combined with its low dielectric constant (Dk) and low dissipation factor (Df), makes it ideal for high - speed and high - frequency applications. In communication equipment, such as 5G base stations where signals need to be transmitted at high speeds with minimal loss, the RO4350B can maintain signal integrity even under high - temperature operating conditions. Its high TG enables it to withstand the heat generated during the operation of high - power components in these applications.

3. Nelco (Viasystems Group) Nelco N4000 - 13
Nelco's N4000 - 13 is a high - TG, high - performance laminate. It features a glass transition temperature suitable for withstanding the rigors of modern PCB manufacturing and application environments. This material is designed to meet the demands of high - density interconnect (HDI) PCBs, which are increasingly used in advanced electronic devices. The N4000 - 13 offers good mechanical properties along with its high TG, providing resistance to warping and ensuring reliable performance in applications where the PCB may be subject to mechanical stress in addition to high temperatures.

4. Panasonic / Megtron? Series (e.g., Megtron 6)
Panasonic's Megtron 6 is a high - TG epoxy - glass material. It has a TG value that allows it to perform well in high - temperature environments. Megtron 6 is known for its excellent adhesion between the copper foil and the substrate, which is important for maintaining the integrity of the PCB circuit. In automotive electronics, where PCBs need to endure harsh temperature conditions under the hood, Megtron 6 can provide the necessary reliability. Its high TG helps prevent delamination of the layers and degradation of electrical performance over time due to heat exposure.?

5. Arlon / DiClad 880
Arlon's DiClad^®880 is a high - TG, low - loss material. It has a relatively high glass transition temperature, making it suitable for applications where both high - temperature resistance and low signal loss are required. In aerospace and defense electronics, where PCBs must operate in extreme conditions, the DiClad 880 can offer the needed performance. Its ability to maintain dimensional stability at high temperatures and its low electrical losses contribute to the overall reliability and functionality of the electronic systems in which it is used.?
These are just a few of the many high - TG material models available in the market. Each brand and model has its own unique set of properties, and the choice of the right material depends on the specific requirements of the PCB application, such as operating temperature range, electrical performance needs, and mechanical stress considerations.

6. ITEQ / IT-180ATC
IT-180ATC It is a high-level high- Tg (175 ℃ by DSC) Multi functional filled epoxy resin with high thermal reliability and resistance CAF Features, suitable for various applications and can pass the 260 ℃ lead-free process.

7. Shengyi
S1000-M:
This material has a top-notch heat resistance with a TG value of 170℃. It can endure T288 for more than 30 minutes, indicating its excellent long - term stability under high-temperature conditions. It's often used in high - end applications where extreme heat resistance is required, such as in aerospace and high - power industrial electronics.

S1170:
With a TG value of 170℃, S1170 is suitable for multi - layer PCB production, especially in scenarios where high - temperature soldering processes are involved, like lead - free soldering. It provides good dimensional stability and helps prevent issues like pad floating and solder joint failures.

ST115G:
Exhibiting a TG value of 175℃, this material offers great insulation and thermal reliability. It has a relatively low coefficient of thermal expansion at the z - axis, which is beneficial for maintaining the integrity of the PCB structure, especially in applications with significant temperature fluctuations.

8. KB
KB-6167F:
This model has a TG value of 170℃. It can withstand high temperatures during PCB manufacturing processes, making it suitable for applications where the PCB will be exposed to elevated temperatures during operation, such as in automotive engine control units or high - performance computing systems.

KB-6168LE:
With a TG value as high as 185℃, it is an ideal choice for applications that demand extremely high heat resistance. For example, in some military and aerospace electronics, where the PCB must operate reliably in harsh thermal environments, KB - 6168LE can meet these strict requirements.

9. NY2170
NY2170 is a medium - high Tg material. Its Tg value is around 170°C, placing it in the medium - Tg PCB category. This material offers good heat resistance, enabling it to withstand common high - temperature processes in PCB manufacturing, such as soldering. It provides reliable performance within a temperature range suitable for applications where the PCB may be exposed to moderately high temperatures during operation. With decent dimensional stability, NY2170 helps maintain the integrity of the PCB structure, reducing the risk of warping or deformation, which is beneficial for ensuring the proper functioning of electronic components mounted on the board.

Shenzhen Meidear Co., Ltd. is a professional manufacturer specializing in 2 - 20 layer high-frequency PCB. It engages in the production and processing of high-frequency microwave circuit boards, hybrid-laminated PCB, multi-layer precision HDI boards, multi-stage blind and buried vias pcb, press-fit holes, stepped boards, back drilling boards, high- layer impedance pcbs, half-hole series, and probe series. For urgent boards, the fastest delivery time is 24 hours, and the minimum order quantity is 1 piece.

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