Full Introduction about Rogers Materials for PCBs

 Rogers Corporation has provided specialized electronic substrate materials to the PCB industry for over 90 years. When precision, performance, and reliability matter most, engineers around the globe trust Rogers laminates and prepregs for their most challenging designs.

This guide will explore popular Rogers PCB materials used across high frequency, thermal management, and high reliability applications. We’ll compare dielectric properties, available thicknesses and constructions, design considerations, common uses, and ordering advice when specifying Rogers materials.

Let’s dive into the premiere circuit substrate brand relied upon by top engineers globally!

Overview of Core Rogers PCB Materials

Rogers offers an extensive portfolio of materials optimized for radio frequency (RF), microwave, high speed digital, and harsh environment circuits. Several core families suit most applications:

RO4000® Series – Ceramic filled thermoplastics with outstanding electrical performance up to 77 GHz suitable for commercial and defense wireless systems. These cost-effective workhorse materials see broad adoption across high frequency and precision analog designs.

RT/duroid® 6000 – Premium PTFE composites with stellar high frequency properties plus thermal and chemical robustness balancing cost with top-tier performance up to 125 GHz. They serve defense, aerospace, semiconductor, and satellite applications.

TC350TM – Thermoset laminates engineered for low loss in multi-layer boards up to 30 GHz like radar, test equipment, and communications infrastructure where thermal performance also matters.

RO3000® Series – Glass microfiber reinforced hydrocarbon materials that are bondable and low in cost. They offer quality RF electricals and good CTE matching to copper for low-cost consumer electronics operating up to 6 GHz like WiFi access points and routers.

CuClad® HC (High Conductivity) – Economical FR-4 epoxies compatible with standard processes having stable dielectric constants while boosting conductivity and thermal transfer thanks to 70% copper loading in finished laminate form.

Several factors differentiate Rogers materials from standard FR-4 circuit boards familiar to most designers:

• Excellent consistency in dielectric properties across fabricated boards and from lot-to-lot
• Sustained stability of electrical characteristics, dimensions, and high frequency performance over temperature
• Wide range of dielectrics to match impedance requirements and address insertion losses
• Low outgassing tendency increases reliability and service lifetimes
• Robust support from Rogers technical staff for optimal material selection and fabrication recommendations

We’ll explore these benefits more while looking at individual material lines. But first, let's cover properties electrically characterizing laminates.

Understanding Dielectric Properties and Definitions

To select an appropriate Rogers material for your design, engineers must have an working grasp of key dielectric specifications, their meaning, and impact on performance. Let’s demystify some common terms:

Dielectric Constant – Indicated by εr, this specifies a material’s relative permeability factor in relation to air (where εr = 1). Dielectric constant strongly influences impedance values achievable for given PCB conductor widths and spacing. Selecting substrates with stable εr helps maintain consistent, predictable impedance performance.

Loss Tangent – Also called dissipation factor (Df), this metric indicates how much signal degrades passing through a dielectric medium. Lower loss tangents improve high frequency efficiency and reduce wasted power converted to heat. Rogers materials typically demonstrate very low Df especially at high frequencies, meaning less signal lost when transmitting data or RF energy.

Coefficient of Thermal Expansion (CTE) – Specifies shrink/expansion characteristics with temperature fluctuation. CTE mismatch between dielectric substrate and copper traces induces shear stress that cracks conductors or delaminates boards when cycling hot/cold temperatures during fabrication or operation. Rogers offers a range of Low-CTE, Mid-CTE and High CTE materials to optimize compatibility with copper where stability matters.

Now equipped with a better understanding of key specifications, let’s explore popular Rogers material lines starting with their signature offerings for high frequency RF designs.

Rogers RO4000 Series High Frequency Materials

The RO4000® series comprises Rogers’ most popular stack of materials balancing electrical performance, cost, and ease of fabrication. This family sets the industry standard for radio frequency circuit substrates. Versions are available with dielectric constants ranging from 3.38 to 10.2 to address various impedance matching needs.

RO4000 Series Product Line Variants

The RO4000 line includes several variants optimized for different applications:

RO4003CTM – The cost-effective workhorse for high volume commercial applications like automotive radar, antenna arrays, general RF component fabrication where consistency matters. εr of 3.38 strikes a nice balance between quality impedance control and fabrication yield.

RO4350BTM – Premium laminate for low loss commercial designs up to 22 GHz like test equipment and microwave communications infrastructure. Its lower εr of 3.48 supports tighter impedance tolerances.

RO4835TM – High εr of 3.48 drives wider lines/spaces relaxing fabrication tolerances while reducing layer counts in multilayer RF circuit boards or modules requiring shielding across layers.

RO4450FTM – Incredibly stable dielectric constant of 3.52 with low loss tangent for narrow band applications. Outstanding consistency for aerospace and defense projects with tight electrical specifications.

RO4725JXTTM – Glass reinforced hydrocarbon laminate which is together into one single fused laminate base for maintaining the best property for the application.

RT/duroid® 5880 – PTFE-ceramic composite with high thermal conductivity for excellent thermal stability and survivability suited for rugged antenna and radar electronics.

Benefits of RO4000 Circuit Boards

Some of the signature benefits making the RO4000 series a longstanding market leader include:

Stability – Dielectric constant varies just over +/-0.04 across production lots ensuring consistent, reliable impedance control. PTFE composite reinforcement provides excellent Z-axis CTE matching with copper preventing sheer stress and delamination issues over temperature.

Performance – Low loss tangent averaging under 0.0019 up to 10 GHz and 0.0027 up to 40 GHz minimizes insertion loss as signals transit boards. This preserves signal integrity and efficiency.

Repeatability – Thanks to exceptional consistency in dielectric properties during fabrication, engineers achieve design validation with fewer prototype iterations compared to typical circuit boards. High yields reduce scrapped boards.

Reliability – Low moisture absorption (~0.04%) prolongs life expectancy minimizing electrical leakage and shorting even in humid environments. Rogers data shows exceptional resistance to thermal stress relaxation over decades of operation.

Safety – These halogen-free, lead-free (HDI/HDIF) and fire resistant laminates meet growing environmental regulatory safety standards which is helpful when recycling consumer goods at end-of-life.

RO4000 materials handle the full gamut of PCB processing techniques allowing realization of Rogers’ touted electrical advantages using standard manufacturing methods:

• Subtractive etch – Conventional inner and outer layer processing well suited for commercial boards thanks to robust ductility of dielectric properties and good dimensional stability retaining impedance tolerances after etching.
• Additive plating – Durable thermoplastic films also permit semi-additive processing which lowers costs through reduced material waste. Tight etch tolerances maintain impedance accuracy.
• Laser drilling – Composite thermoplastic films offer cleaner ablation during laser hole formation compared to traditional FR-4 and woven glass.
• AXI (Any Layer Interstitial Via) – Multilayer designs benefit from the ability to form interlayer connections at any interface rather than solely through traditional lamination layers. This unlocks greater routing freedom.
• Multi-beam direct imaging – RO4000 materials demonstrate excellent resolution under multi-beam exposure recipes. Line and space features down to 25/25 μm are achievable.

This unmatched combination of electrical, mechanical, and manufacturing advantages makes the Rogers 4000 series a versatile, reliable choice appropriate for an immense range of wireless and microwave circuits.

Next let’s move on to Rogers’ premium RF substrates.

Rogers RT/duroid Series for Extreme Performance

The RT/duroid® line represents Rogers’ elite tier of high frequency circuit materials engineered for extreme stability, low loss, and exceptional consistency even under challenging thermal and environmental conditions. These PTFE composites balance outstanding electricals with ruggedness meeting strict military specifications. Noteworthy variants include:

RT/duroid® 5870 /5880 – Glass microfiber reinforced PTFE composites with low dielectric constant around 2.33 delivering superb thermal performance plus stability from -65°C to 170°C. They offer low loss down to 100+ GHz frequencies for satellite applications. The 5880 glass style supports automated handling well suited to mass production environments.

RT/duroid® 6002/6202 – Next generation ceramic reinforced PTFE materials engineered for improved fabrication yields, extended frequency range reaching 125 GHz thanks to ultra-low Dk and Df properties, plus enhanced reliability under thermal shock/cycling. 6202 achieves lowest loss tangent with average Df of just 0.0012 from 2-100 GHz - truly exceptional! This empowers next-gen aerospace and defense electronics requiring flawless electricals where cost matters less than un