Introduction

Printed circuit boards (PCBs) are essential components in almost every electronic device we use today. As electronic devices continue getting smaller, faster and more powerful, the demands on PCB materials have increased significantly. This is especially true for boards used in high frequency applications like 5G, WiFi 6, and millimeter wave devices. For these cutting-edge applications, Rogers Corporation’s IsoClad 933 material has become the preferred PCB substrate.

Rogers IsoClad 933 is a ceramic-filled, PTFE composite material that offers exceptional electrical performance along with great mechanical stability. Its low dissipation factor and tight dielectric constant tolerance across a wide frequency range make it the ideal choice for designing high frequency circuits and antennas.

In this article, we will take a closer look at Rogers IsoClad 933, understand its unique properties and discuss why it has become the go-to material for high frequency PCBs.

Properties of Rogers IsoClad 933

Rogers IsoClad 933 stands out due to its unique combination of electrical, mechanical and thermal properties. Here are some of the key characteristics of this material:

Electrical Properties

• Extremely low loss tangent of 0.0013 at 10 GHz
• Stable dielectric constant of 3.33 ± 0.05 over a wide frequency range
• Low Z-axis thermal coefficient of dielectric constant = +42 ppm/°C

Frequency	Dielectric Constant	Loss Tangent
1 MHz	3.33	0.0013
10 MHz	3.33	0.0013
100 MHz	3.33	0.0013
1 GHz	3.33	0.0013
10 GHz	3.33	0.0013

The low and stable dielectric constant and loss tangent allow IsoClad 933 to support extremely high frequency signals with minimal signal loss and distortion. This makes it suitable for designing high speed digital circuits, microwave circuits, antennas, and other leading-edge applications.

Mechanical Properties

• Withstands high temperatures up to 280°C during lamination
• High tensile modulus of 4.83 GPa (700 ksi) along grain direction
• Low Z-axis CTE of 41 ppm/°C matches standard FR4 laminates
• Excellent dimensional stability during thermal cycling

The outstanding mechanical properties allow IsoClad 933 boards to withstand the rigors of PCB fabrication and assembly processes. The close CTE match with FR4 also minimizes via reliability issues.

Thermal Properties

• High thermal conductivity of 1.44 W/m/K
• Low specific heat capacity of 1 kJ/kg/K

The excellent thermal conductivity quickly dissipates heat from high power components. This improves thermal management and enhances reliability.

Benefits of Using Rogers IsoClad 933

Rogers IsoClad 933 laminates offer several advantages that make them the top choice for cutting-edge RF designs:

Superior High Frequency Performance

The low dielectric constant and loss deliver exceptional performance for microwave, millimeter wave and antenna applications requiring signals above 10 GHz. The stable electrical properties also facilitate accurate modeling and simulation.

Ideal for High Speed Digital Circuits

With a low dissipation factor and tight dielectric constant tolerance, IsoClad 933 supports ultra-high speed signal propagation in dense, multi-layer digital circuits. This makes it suitable for data centers, networking, and telecom applications.

Reliable Performance

The thermal and mechanical stability of IsoClad 933 prevents electrical performance degradation over time and under challenging operating conditions. This results in highly reliable PCB performance over the entire product lifetime.

Easy Integration with Standard FR4

The CTE and thermal properties of IsoClad 933 match well with conventional FR4 laminates. This allows combining IsoClad 933 high frequency layers seamlessly with standard FR4 layers in a PCB stackup.

Reduced Costs

By enabling the use of thinner dielectrics and tighter line spacing, IsoClad 933 allows reducing the number of layers in complex designs. This lowers PCB costs through improved fabrication yields and material savings.

Applications Using Rogers IsoClad 933

The unique benefits of Rogers IsoClad 933 make it the ideal choice for a wide variety of cutting-edge applications:

5G Wireless Infrastructure

IsoClad 933 is widely used in 5G NR base stations and massive MIMO antenna arrays operating above 6 GHz. Its low loss allows packing more transceivers in a compact area to enable beamforming.

Satellite Communications

Low loss and stable electrical performance up to millimeter wave frequencies make IsoClad 933 suitable for satcom antenna PCBs and waveguide transitions.

High Density Interconnects

The excellent signal integrity of IsoClad 933 at multi-gigabit data rates enables dense cabling in data centers, network switches and test equipment.

Automotive Radar

Stable dielectric properties up to 100 GHz allow IsoClad 933 to meet the demands of next-gen radar sensors for autonomous vehicles.

Aerospace and Defense

For airborne applications, IsoClad 933 provides reliable RF performance under wide temperature variations and exposure to humidity.

With its unrivaled high frequency performance and reliability, Rogers IsoClad 933 continues to be the trusted choice for cutting-edge RF and digital systems.

Rogers IsoClad 933 PCB Stackup Design Guidelines

To fully leverage the benefits of Rogers IsoClad 933 in a multilayer PCB, the stackup must be designed intelligently by following certain guidelines:

Place IsoClad 933 layers closest to components

As IsoClad 933 layers have the lowest loss, they should be placed closest to the components and ICs driving signals. This minimizes loss between the drivers and transmission lines.

Use thick IsoClad 933 cores for shielding

Thicker cores can provide shielding between critical layers containing high speed traces. This prevents signal coupling and crosstalk.

Pair IsoClad 933 layers with ground planes

Signal layers should be paired with continuous ground planes on adjacent layers wherever possible. This provides controlled impedance environment.

Limit layer transitions

Minimize transitions between IsoClad 933 and FR4 layers in the stackup. Use direct layer transitions wherever possible to avoid discontinuities.

Maintain symmetry

Keep the stackup symmetric about the center whenever possible. This results in uniform distribution of mechanical stress.

Following these guidelines will result in a PCB stackup optimized for utilizing the superior performance of Rogers IsoClad 933 material.

IsoClad 933 High Frequency PCB Fabrication

To produce quality PCBs using IsoClad 933, fabrication shops need to follow certain key processes:

• Material Handling – IsoClad 933 cores should be stored in low humidity environment and allowed to stabilize to room temperature prior to inner layer production.
• Surface Treatment – Proper chemical or mechanical processes must prepare the surfaces for improved adhesion to prepreg and resist.
• Imaging – High resolution lithography processes are essential to achieve fine features and tight tolerances.
• Plating – Highly controlled electroless and electrolytic copper plating is needed to obtain desired copper thickness across panels.
• Etching – The etching process must deliver high undercut control to hold tight trace spacing and achieve impedance targets.
• Lamination – Using the recommended lamination cycle is critical to minimize Z-axis CTE and obtain consistent dielectric thickness.
• Drilling – Excellent drill bit quality and low drilling parameters preserve the integrity of plated holes.
• Hole Wall Preparation – A combination of chemical and plasma processes clean residues from hole walls.
• Final Surfaces – Immunoelectroless nickel-gold (ENIG) or immersion silver (ImmAg) produce solder-leach resistant surface finishes.

Following these critical fabrication processes will result in high quality PCBs that can take full advantage of IsoClad 933’s superior high frequency performance.

Rogers IsoClad® 933 PCB Material – FAQs

Here are answers to some frequently asked questions about Rogers IsoClad 933 high frequency PCB material:

Q: What is the difference between IsoClad and regular FR4 material?

A: IsoClad 933 uses a PTFE composite dielectric which gives it much lower loss and tighter dielectric constant tolerance compared to standard glass-reinforced FR4 laminates. This makes it suitable for high frequency applications.

Q: Can I use IsoClad 933 with conventional FR4 in a single PCB stackup?

A: Yes, IsoClad 933 can be easily integrated with FR4 layers in a multilayer board due to excellent CTE matching. High frequency signals can be routed on IsoClad while low frequency signals use FR4 layers.

Q: Does Rogers IsoClad 933 require special PCB fabrication processes?

A: A few critical processes like surface treatment, lamination and drilling may need tight control. But otherwise it can leverage existing PCB production processes.

Q: What are the typical applications for Rogers IsoClad 933 material?

A: It is widely used in 5G systems, radars, satellite communication, high-speed digital circuits and other cutting-edge RF and microwave applications.

Q: What is the typical lead time for procuring Rogers IsoClad 933 material?

A: Depending on availability, lead times can range from 2-8 weeks. Planning designs ahead and ordering early is recommended for timely delivery.

Conclusion

With its unparalleled electrical performance, mechanical stability and ease of integration with FR4, Rogers IsoClad 933 has become the preferred material for high frequency PCB applications. The low loss and stable dielectric constant over a wide frequency range make it ideal for 5G, WiFi 6, satcom, automotive radar and other leading-edge microwave and mmWave devices.

Following recommended stackup and fabrication guidelines allows PCB designers and manufacturers to fully utilize the performance benefits of IsoClad 933. As electronic systems continue getting faster and more complex, Rogers IsoClad 933 provides a robust, reliable technology platform to build next-generation RF and digital products.