TC350 Plus Laminates: Complete Guide to Specs, Applications & PCB Design

If you’ve been hunting for a thermally conductive PCB substrate that won’t break the bank or your drill bits, TC350 Plus laminates deserve a spot on your shortlist. After working with dozens of high-frequency materials over the years, I can tell you that this Rogers Corporation product hits a sweet spot that few competitors match.

This guide breaks down everything you need to know about TC350 Plus laminates—from raw technical specifications to real-world fabrication tips that’ll save you headaches in production.

What Are TC350 Plus Laminates?

TC350 Plus laminates are ceramic-filled, PTFE-based composite materials reinforced with woven glass fabric. Rogers Corporation developed them specifically for high-power RF and microwave applications where thermal management is critical.

The “Plus” variant builds on the original TC350 formula with an upgraded filler system. This seemingly small change delivers two practical benefits that matter in production: better drilling performance and reduced tool wear. If you’ve ever watched your carbide bits chew through abrasive ceramic-filled substrates, you’ll appreciate this improvement.

Key Material Composition

The combination of PTFE and ceramic fillers creates a substrate with thermal conductivity roughly twice that of standard RT/duroid 6000 products. That’s a significant jump when you’re trying to pull heat away from power transistors.

TC350 Plus Laminates Technical Specifications

Numbers matter when you’re selecting materials. Here’s the complete specification table for TC350 Plus laminates based on Rogers Corporation datasheet values:

Electrical Properties

Thermal Properties

Mechanical Properties

Available Thicknesses

TC350 Plus laminates come in several standard thicknesses to accommodate different design requirements:

Custom thicknesses can be requested through Rogers Corporation for specialized applications.

Why TC350 Plus Laminates Stand Out

Understanding the technical advantages of TC350 Plus helps justify its use over lower-cost alternatives and positions it against higher-priced aerospace materials.

Superior Thermal Conductivity for High-Power Designs

At 1.24 W/(m·K), the thermal conductivity of TC350 Plus laminates significantly outperforms standard FR-4 (around 0.3 W/(m·K)) and even beats many competing PTFE-based materials. When you’re designing power amplifiers pushing 100W or more, this thermal performance translates directly into lower junction temperatures and longer device life.

I’ve seen too many designs fail thermal testing because engineers picked materials based on electrical specs alone. Heat kills power electronics. TC350 Plus gives you a fighting chance to manage thermal loads without exotic (and expensive) solutions like embedded heat coins.

Practical thermal benefits:

• Junction temperature reduction of 20-40°C versus FR-4 at equivalent power levels
• Improved thermal spreading reduces hot spots under active devices
• Enables higher power density designs
• Complements external thermal management (heatsinks, coins, thermal vias)

The ceramic filler system dispersed throughout the PTFE matrix creates thermally conductive pathways that standard PTFE lacks. This isn’t just marketing—you’ll see measurable temperature differences on the bench.

Low Loss Tangent for Minimal Signal Degradation

The loss tangent of 0.0017 at 10 GHz keeps RF losses manageable across a wide frequency range. This matters for efficiency—every dB of loss in your transmission lines means more heat in your amplifier stages and less power at your output.

For designs operating below 10 GHz, TC350 Plus delivers electrical performance comparable to much more expensive aerospace-grade materials. You’re not leaving performance on the table by choosing a commercial-grade substrate.

Excellent Dimensional Stability

Woven glass reinforcement gives TC350 Plus laminates excellent dimensional stability during thermal cycling. The combination of controlled CTE values and glass fabric prevents the warping and registration issues that plague less stable materials.

This stability directly impacts your yield rates. Boards that stay flat through lamination and assembly solder properly. Boards that warp become scrap.

Improved Drilling Performance

The advanced filler system in TC350 Plus was specifically engineered to reduce abrasion on cutting tools. Compared to the standard TC350 and other ceramic-filled PTFE materials, you’ll see noticeably longer drill bit life.

Rogers suggests the “twelve-inch rule” may apply to TC350 Plus—meaning you can drill approximately 12 inches of substrate before changing tools, versus the “six-inch rule” typical for standard TC350. That’s potentially double the tool life, which adds up fast in volume production.

TC350 Plus Laminates vs. Competing Materials

Choosing the right high-frequency laminate means understanding trade-offs. Here’s how TC350 Plus stacks up against common alternatives used in similar applications.

Comprehensive Comparison Table

Detailed Material Comparisons

TC350 Plus vs. TC350 (Standard): The Plus variant offers approximately 8% higher thermal conductivity and 15% lower loss tangent. More significantly, the improved filler system doubles potential drill bit life. For new designs, TC350 Plus is the logical choice unless you have existing tooling or qualification tied to standard TC350.

TC350 Plus vs. RO4350B: RO4350B processes more like FR-4, making it attractive for fabricators unfamiliar with PTFE. However, TC350 Plus offers twice the thermal conductivity—a decisive advantage for power amplifiers above 100W. Choose RO4350B for lower-power applications where ease of fabrication matters more than thermal performance.

TC350 Plus vs. RT/duroid 6035HTC: RT/duroid 6035HTC offers slightly better thermal conductivity (1.44 vs. 1.24 W/m·K) and lower loss tangent. It’s the premium choice for aerospace applications where cost is secondary to performance. TC350 Plus provides roughly 80% of the performance at a significantly lower price point—ideal for commercial applications.

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When to Choose TC350 Plus Laminates

TC350 Plus makes sense when:

• Your design operates above 50W continuous power
• Thermal management is critical but aerospace-grade materials exceed your budget
• You need better drilling economics than standard ceramic-filled PTFE
• Operating frequencies fall between 1 GHz and 10 GHz
• UL 94 V-0 flammability rating is required
• Lead-free assembly compatibility is necessary

Consider alternatives when:

• Budget is extremely tight (FR-4 or RO3003 might suffice)
• You need the absolute lowest loss tangent (RT/duroid 5880)
• Maximum thermal conductivity is non-negotiable (RT/duroid 6035HTC)
• Processing must exactly match FR-4 workflows (RO4350B)
• Frequencies exceed 20 GHz (lower Dk materials may be preferable)

Applications for TC350 Plus Laminates

TC350 Plus laminates find their niche in applications where thermal management meets high-frequency performance requirements. Understanding where this material excels helps you make informed design decisions.

Power Amplifiers

Power amplifier design is the flagship application for TC350 Plus. The combination of low loss and high thermal conductivity allows designers to build higher-power stages without excessive thermal derating. Solid-state power amplifiers in wireless infrastructure, industrial heating, and radar systems all benefit from these properties.

Modern solid-state microwave ovens represent an emerging application area. Unlike traditional magnetron-based ovens, solid-state designs offer precise power control and frequency agility—but they generate significant heat that TC350 Plus helps manage effectively. These systems typically operate around 2.45 GHz and can deliver 250W or more per amplifier module.

Power amplifier design benefits:

• Lower operating temperatures extend transistor life
• Reduced thermal derating allows higher output power from smaller packages
• Better thermal uniformity across the substrate improves consistency
• Low dielectric loss maximizes amplifier efficiency

RF Passive Components

Several passive component types benefit from TC350 Plus laminates:

• Directional Couplers: Thermal stability prevents impedance drift during operation
• Power Dividers: Wilkinson dividers handle higher power with better thermal dissipation
• Bandpass Filters: Low loss maintains filter selectivity and insertion loss specs
• Combiners: High-power combining stages stay cooler and more reliable
• Hybrid Couplers: Temperature-stable Dk maintains coupling accuracy
• Lange Couplers: Wideband performance benefits from consistent dielectric properties

5G and Wireless Infrastructure

Next-generation wireless systems operate at higher frequencies and power levels than their predecessors. TC350 Plus provides a cost-effective substrate for massive MIMO antenna arrays and high-power base station amplifiers where thermal constraints limit design options.

Specific 5G applications include:

• Beamforming antenna feeds
• High-power distributed antenna systems (DAS)
• Small cell base station amplifiers
• Millimeter-wave downconverters (with appropriate frequency derating)

Industrial and Scientific Equipment

Industrial heating applications, medical equipment, and scientific instrumentation often require high-power RF circuits operating continuously. TC350 Plus offers the reliability and thermal performance these demanding environments require.

Industrial applications include:

• Plasma generators for semiconductor manufacturing
• RF heating systems for material processing
• Particle accelerator RF systems
• Industrial microwave heating equipment

Defense and Aerospace

While aerospace programs often specify higher-cost materials like RT/duroid 6035HTC, TC350 Plus serves well in defense applications where commercial-grade materials are acceptable. Electronic warfare systems, radar components, and communications equipment all represent viable applications.

Defense-related uses include:

• Ground-based radar modules
• Communication system amplifiers
• Electronic countermeasure equipment
• Unmanned aerial vehicle (UAV) communications

PCB Fabrication Guidelines for TC350 Plus Laminates

Getting good results from TC350 Plus requires understanding its fabrication characteristics. Here are practical guidelines based on Rogers Corporation recommendations and real-world experience.

Storage and Handling

TC350 Plus is a soft substrate compared to FR-4 or thermoset materials. Handle panels with care to prevent surface damage.

Some copper surface oxidation can occur during storage, particularly in elevated temperature and humidity conditions. This oxidation removes easily during standard microetch processing.

Drilling Parameters

Drilling PTFE composites requires adjusted parameters compared to FR-4. Here are recommended settings for common drill sizes:

Key drilling tips:

• Use new carbide drills—standard or undercut styles work well
• Phenolic composite entry boards (0.010″-0.030″ thick) recommended
• Exit board thickness should exceed 0.060″
• Stack heights for double-sided boards can match flute length
• Multilayer boards typically drill in stacks of one

The “twelve-inch rule” provides a starting point for tool life estimation with TC350 Plus. For a 0.060″ thick panel, that translates to roughly 200 holes before changing drills (12″ / 0.060″ = 200).

Surface Preparation

PTFE surfaces require activation before plating. Standard processing follows this sequence:

1. Chemical cleaning: Remove oxidation and contamination
2. Plasma treatment: CF4/O2 plasma activates PTFE surfaces for adhesion
3. Glass etch: Reduces risk of plated nodules (TC Series may require this step)
4. Electroless copper: Deposit seed layer for subsequent plating

Plating Considerations

Direct metallization processes like graphite or palladium-based systems work with TC350 Plus after proper surface activation. Electroless copper provides excellent adhesion when surfaces are properly prepared.

For multilayer constructions, the adhesive system (not the TC350 Plus itself) may require desmear using permanganate or plasma processes.

Solder Mask and Final Finishes

TC350 Plus is compatible with most LPI solder masks after proper surface preparation:

1. Rinse in warm or hot water (20-30 minutes)
2. Bake at 125°C (260°F) for 60 minutes
3. Vacuum bake preferred if available
4. Apply solder mask per manufacturer instructions

Standard final finishes including HASL, immersion tin, immersion silver, ENIG, and OSP have all been successfully applied to TC350 Plus laminates. A rinse/bake cycle should precede HASL or reflow operations.

Design Considerations for TC350 Plus PCBs

Impedance Control

With a nominal Dk of 3.5, TC350 Plus allows for reasonable trace widths in 50-ohm designs. For a 0.020″ substrate with 1 oz copper, expect microstrip line widths around 0.047″ (1.2 mm).

Rogers provides the MWI (Microwave Impedance) Calculator—a free online tool that handles impedance calculations for their materials. Use it. Don’t trust generic calculators that don’t account for material-specific characteristics.

Important impedance design notes:

• Dk tolerance: ±0.05 typical—factor this into your impedance budget
• Process direction matters—specify Dk measurement orientation
• Temperature coefficient of Dk: The dielectric constant remains stable across operating temperatures
• Surface roughness affects high-frequency loss—the standard smooth copper foil (Rq = 1.0 µm) minimizes this

Layer Stackup Recommendations

For multilayer designs using TC350 Plus, consider these stackup strategies:

Simple 2-Layer Design:

• Top: Signal layer (copper)
• Core: TC350 Plus laminate (0.020″ typical)
• Bottom: Ground plane

4-Layer High-Power Design:

• Layer 1: RF signal traces
• Core 1: TC350 Plus (0.020″)
• Layer 2: Ground plane
• Prepreg: Bondply or compatible adhesive
• Layer 3: Power distribution
• Core 2: FR-4 (for non-critical layers)
• Layer 4: Ground/shield

The key principle: place TC350 Plus where you need its thermal and electrical properties. Don’t waste expensive material on layers that could use FR-4.

Thermal Via Design

When heat dissipation from active devices is critical, thermal vias provide a direct path through the substrate. For TC350 Plus designs:

• Via diameter: 0.010″-0.015″ typical
• Via pitch: 0.030″-0.050″ center-to-center
• Fill: Conductive epoxy or copper-plated solid vias for best thermal transfer
• Placement: Directly under heat-generating components

Even with TC350 Plus’s excellent lateral thermal conductivity, thermal vias remain the most effective path for removing heat from the PCB.

Hybrid Stackups

Cost-conscious designs often mix Rogers PCB materials with FR-4. TC350 Plus can be incorporated into hybrid multilayer stackups where only critical RF layers use the high-performance material.

Typical hybrid approaches:

• TC350 Plus for signal layers carrying high-power RF
• FR-4 for power distribution and low-frequency control circuits
• Proper bonding films between dissimilar materials

Work with your PCB fabricator to verify compatibility and lamination parameters for hybrid constructions.

Cost and Sourcing Considerations

TC350 Plus laminates occupy the middle ground in high-frequency material pricing—more expensive than FR-4 or basic Rogers materials, but considerably less than aerospace-grade alternatives.

Typical Price Ranges

Prices vary significantly based on volume, thickness, copper weight, and market conditions. Request current quotes from authorized distributors for accurate pricing.

Cost Optimization Strategies

• Panel optimization: Maximize circuit density per panel to reduce per-unit material cost
• Hybrid stackups: Use TC350 Plus only where thermal/electrical requirements demand it
• Standard thicknesses: Avoid custom thicknesses unless absolutely necessary
• Volume commitments: Higher volumes typically command better pricing
• Alternative sourcing: Work with your fabricator—they may have stock or alternative sources

Selecting a TC350 Plus PCB Manufacturer

Not every PCB shop handles high-frequency materials well. Look for these qualifications when selecting a manufacturer:

Essential Qualifications

Questions to Ask

1. How many TC350 Plus (or TC Series) boards have you produced?
2. What is your typical yield rate on PTFE-based materials?
3. Do you have plasma treatment capability in-house?
4. Can you provide RF test data for impedance-controlled designs?
5. What is your lead time for prototype quantities?

Useful Resources and Downloads

Official Rogers Corporation Resources

Industry Standards

Frequently Asked Questions About TC350 Plus Laminates

What is the difference between TC350 and TC350 Plus laminates?

TC350 Plus features an improved filler system compared to standard TC350. This delivers two main benefits: a slightly higher thermal conductivity (1.24 vs. 1.15 W/m·K) and significantly better drilling performance with reduced tool wear. The electrical specifications remain similar, with TC350 Plus achieving a slightly lower loss tangent (0.0017 vs. 0.0020 at 10 GHz). For most new designs requiring TC Series materials, TC350 Plus is the preferred choice unless specific legacy requirements dictate otherwise.

Can TC350 Plus laminates be processed using standard FR-4 fabrication methods?

TC350 Plus requires modified processing compared to FR-4. While basic operations like imaging and etching are similar, several steps differ significantly. Drilling requires adjusted speeds, feeds, and more frequent tool changes. PTFE surfaces need plasma activation before plating. Desmear processes typically used for FR-4 don’t affect PTFE and are unnecessary unless adhesive systems require them. Work with a fabricator experienced in PTFE-based materials for best results.

What frequency range is TC350 Plus suitable for?

TC350 Plus performs well from DC through approximately 10 GHz, with the loss tangent specification measured at 10 GHz. The material can be used at higher frequencies, though losses increase. For applications above 10 GHz where minimum loss is critical, consider materials like RT/duroid 5880. For most commercial and industrial applications in the 1-10 GHz range, TC350 Plus offers an excellent balance of performance and cost.

How does TC350 Plus compare to RO4350B for power amplifier designs?

Both materials work well for power amplifiers, but they optimize differently. TC350 Plus offers roughly twice the thermal conductivity of RO4350B (1.24 vs. 0.62 W/m·K), making it better suited for high-power applications where heat extraction is critical. RO4350B has lower loss tangent (0.0037 vs. 0.0017) but the thermal penalty becomes significant above 50-100W. For power amplifiers exceeding 100W continuous, TC350 Plus typically provides better overall performance.

Is TC350 Plus RoHS compliant?

Yes, TC350 Plus laminates are RoHS compliant and lead-free assembly compatible. The material meets UL 94 V-0 flammability requirements, making it suitable for commercial applications with regulatory compliance requirements. Verify current compliance status with Rogers Corporation for specific certification requirements.

Conclusion

TC350 Plus laminates represent a practical choice for engineers designing high-power RF circuits who need thermal performance beyond what standard materials offer. The combination of 1.24 W/(m·K) thermal conductivity, low 0.0017 loss tangent, and improved drilling economics makes TC350 Plus a compelling option for power amplifiers, combiners, and other high-power components.

The material isn’t perfect for every application—aerospace programs may require higher-performance alternatives, and cost-sensitive designs might manage with less expensive substrates. But for commercial and industrial high-power RF applications in the 1-10 GHz range, TC350 Plus hits a sweet spot that’s hard to match.

Work with an experienced high-frequency PCB fabricator, follow Rogers Corporation’s processing guidelines, and you’ll get reliable results from this capable material.