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Important Facts You Need to Know About Isola FR406

Several PCB materials are available for PCB fabrication. However, not all materials guarantee functionality and reliability. Therefore, it is important to know more about PCB materials. In this article, we will be looking at one of the best-quality PCB materials for your PCB fabrication. The Isola FR406 is our focus in this article.

What Does the Isola FR406 PCB Material Mean?

The Isola FR406 PCB material is an epoxy resin material designed by Isola. The composition of this material enables it to be suitable for multilayer PCBs fabrication.

Also, this laminate features a stable dielectric constant and high glass transition temperature. This laminate isn’t only ideal for multilayer boards; it also works for single sided PCBs.

What Properties Does Isola FR406 Offer?

Isola FR406 PCB material offers exceptional properties. These properties contribute to its high performance.

High glass transition temperature

The Tg of Isola FR406 is 170 degrees Celsius. Therefore, this PCB laminate features a high glass transition temperature. Also, it is ideal for high performance applications. High Tg material plays a crucial role in PCB fabrication. This property contributes to the thermal performance of a circuit board.

Low Z-axis CTE

The Z-axis CTE of this material is 60ppm/ºC before glass transition temperature. The CTE after glass transition temperature is 250ppm/ºC.  Therefore, Isola FR406 offers low coefficient of thermal expansion.

Low and stable dielectric constant

The dielectric constant of Isola FR406 is 3.93. This means that Isola FR406 PCB material features a low dielectric constant. Also, this electrical property indicates that this material is suitable for high frequency applications. In addition, Isola FR406 can reduce electric power loss when used in any applications.

High Decomposition temperature

The decomposition temperature of this material is 300 degrees Celsius. Therefore, Isola FR406 PCB material will chemically decompose when it operates above 300 degrees Celsius. The decomposition temperature of this material is high.

Square weave E-glass reinforcement

Isola FR406 PCB materials features square weave E-glass reinforcement. Therefore, this improves the mechanical properties of this material. Isola FR406 features a material made of electronic glass fiber cloth.

What is the Significance of Relative Thermal Index (RTI) in Isola FR406?

RTI plays a crucial role in determining the performance of a PCB material. This index describes the highest service temperature at which Isola FR406 remains within limits over a long time. Also, it defines the ability of a PCB material to retain thermal degradation. Therefore, this index specifies the maximum temperature you can expose Isola FR406 to avoid negative effect on its performance.

Isola FR406 is a high-frequency PCB material will generate high temperature conditions. Any failure in high temperature applications can have a negative impact. Therefore, it is important to utilize the appropriate material. Also, ensure the CTE of this laminate conforms to other materials.

Therefore, this protects Isola FR406 laminate form any damage. The relative thermal index is an important property to consider. In addition, the MOT (Maximum Operating Temperature) is a UL rating that backs RTI. It indicates the maximum temperature a PCB construction can withstand without changes in its properties. However, the RTI of Isola FR406 must exceed MOT.

Resin Systems in Isola FR406

There are several resin systems used in Isola FR406. However, the commonest resin systems are epoxy-based. The different types of epoxy resin systems are:

Tetra-functional modified systems

This epoxy resin system offers a high Tg value due to its enhanced cross-linking. Also, this system provides enhanced resistance to solvents and chemicals used in Isola FR406 manufacturing.

Thermally conductive epoxy resin systems

These resin systems features reasonable Tc values. The normal Tc for these systems varies from 1 to 3 W/m/K. Also, these systems use thermally conductive fillers. In addition, they incorporate a resin technology that is free of lead. Also, these systems encourage heat transfer through the laminate.

Di-functional epoxy resin

This begins with brominated bisphenol-A and adds fillers and accelerators. There are different di-functional epoxies. These are low-end di-functional systems and modified di-functional systems. The low-end system has a Tg between 110 to 130 degrees Celsius. The modified systems feature multi-functional and tetra-functional epoxy resins. Therefore, the Tg ranges from 135 to 160 degrees Celsius.

Low-flow epoxy systems

These systems have a restricted flow. Therefore, this makes them ideal for rigid-flex Isola PCB fabrication. Also, they are ideal for heat sink bonding. However, they have various Tg values.

The Effects of Heatup Rate and Pressure in Isola FR406 Lamination

The heat-up rate plays a crucial role in Isola FR406 resin systems. Therefore, it is important to regulate the rate of heat-up during multilayer Isola PCB fabrication. It is crucial in controlling the temperature rise rate via the flow period. This period starts from when resin system begins to melt and when it reaches a high viscosity.

The resin system may not flow well when the rate of heat-up is slow. Meanwhile, if the rate is fast, there might be uneven flow. Slow heat rise can result in high melt viscosity. Therefore, the resin may not be able to flow around the copper structure. Fast rate of heat-up results in higher FR406 resin flow.

Pressure can impact Isola FR406 lamination. When there is low pressure, this PCB material may feature poor interlaminar bonding. Also, it might have low-pressure areas that feature inadequate resin flow. The solution to this is to increase the pressure slightly. You can also adjust the heating rate to open the lamination window.

Also, the inner layers might experience distortion when the lamination pressure is very high. Also, high pressure can lead to glass knuckles crushing against inner layer’ traces. The heat-up rate is important since general flow depends on the resin melt viscosity. Also, it depends on the lamination pressure. The heat rate determines the melt viscosity to an extent. Therefore, it is ideal to keep a baseline heat-up rate of 10 °F for each minute.


The Isola FR406 PCB material is specifically designed with more advance features. It is offers great performance for FR-4 processing. Also, this laminate can function well in a wide range of applications. Therefore, it continues to gain popularity in the PCB industry.




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