CoolSpan TECA Film | Thermally Conductive Adhesive

What Is CoolSpan TECA Film?

CoolSpan TECA (Thermally and Electrically Conductive Adhesive) film is a thermoset adhesive manufactured by Rogers Corporation, designed to bond high-frequency laminates directly to metal carriers, heat sinks, or embedded copper coins. It provides bulk thermal conductivity of approximately 6 W/m·K—roughly 20× higher than conventional FR-4 prepreg—while maintaining a dissipation factor (Df) below 0.005 at 10 GHz. For power amplifiers, phased-array antenna modules, and radar T/R modules where junction-to-case thermal resistance limits performance, CoolSpan TECA film replaces mechanical fasteners and thermal greases with a lamination-compatible, void-free bond line.

Key Material Properties

The table below summarizes the published parameters engineers need when adding CoolSpan TECA film to a stackup model or thermal simulation. All values are at room temperature unless noted.

Because the film is loaded with thermally conductive—and optionally electrically conductive—ceramic or metallic fillers, its Dk of ~4.0 is higher than unfilled PTFE adhesives (Dk ≈ 2.3–2.6). That matters for impedance modeling: the CoolSpan layer must be explicitly entered in your stackup, not treated as a negligible glue line.

Where CoolSpan TECA Film Is Used

Power Amplifier Modules

GaN and GaAs MMIC die generate heat densities above 100 W/cm². Mounting the RF substrate onto a copper–molybdenum or copper–tungsten carrier with CoolSpan TECA film creates a metallurgical-quality thermal path. Compared with silver-filled epoxy paste, the film offers uniform bond-line thickness and no squeeze-out into RF cavities.

Phased-Array and Radar T/R Modules

Active electronically scanned arrays (AESAs) for X-band and Ku-band radar pack hundreds of transmit/receive channels into tight lattice spacings. Each channel dissipates several watts, and the aggregate heat must reach a cold plate through the PCB substrate. CoolSpan TECA film bonds Rogers RO3003G2 laminates or similar low-loss PTFE cores to aluminum or copper heat spreaders without introducing a high-loss adhesive layer in the RF path.

Embedded Coin and Heat-Slug Assemblies

Some multilayer RF boards embed copper coins directly beneath high-power components. CoolSpan TECA film bonds the coin to the surrounding laminate layers, providing both mechanical retention and thermal conduction. This technique is common in military and space-qualified assemblies where alumina ceramic RF substrates or soft PTFE laminates must interface with metallic thermal hardware.

Automotive Radar at 77 GHz

Millimeter-wave radar modules for ADAS increasingly use Isola Astra MT77 or Rogers RO3003-series laminates. When the MMIC dissipation pushes beyond passive cooling limits, CoolSpan TECA film provides a compact thermal solution that survives AEC-Q qualification temperature cycling (−40 to +125 °C, 1 000 cycles).

Lamination and Processing Guidelines

CoolSpan TECA film is processed in a vacuum-assisted hydraulic press, much like standard multilayer lamination. The critical differences are temperature, pressure and surface preparation.

1. Surface preparation: Metal surfaces (copper coins, aluminum heat sinks) must be chemically cleaned and micro-etched or oxide-treated. Contamination or smooth surfaces reduce peel strength below the 5.3 N/mm minimum.
2. Pre-bake: Bake film rolls at 100 °C for 1 hour if stored in non-sealed conditions, to drive off absorbed moisture that causes voids.
3. Layup: Place the film between the laminate and the metal surface. For thick bond lines, two plies of 1.5 mil film can be stacked.
4. Press cycle: Ramp to 220–250 °C at 3–5 °C/min under full vacuum (< 25 mm Hg). Apply 1.4–2.8 MPa at the target temperature and hold for 60–90 minutes.
5. Cool-down: Cool under pressure at ≤ 3 °C/min to below 100 °C before releasing vacuum. Fast cooling risks delamination from CTE mismatch stress.

The electrically conductive variant of CoolSpan TECA film creates a DC ground path through the adhesive, eliminating the need for plated through-holes or via fences solely for grounding. This simplifies the layout of cavity-backed patch antennas and waveguide transitions where continuous ground planes are critical.

Thermal Design Considerations

Even at 6 W/m·K, the adhesive layer adds measurable thermal resistance. For a 1.5 mil (0.038 mm) bond line over a 10 × 10 mm footprint:

R_th = t / (k × A) = 0.000038 / (6 × 0.0001) = 0.063 °C/W

That is negligible for most single-device applications. But in a dense T/R module with 64 channels, cumulative heat flux through a shared bond area can push the interface temperature rise to several degrees—enough to matter when the MMIC junction temperature budget is tight. Always model the CoolSpan layer explicitly in your FEA thermal simulation rather than assuming it is zero resistance.

Adhesive Coverage Estimation for SMD and Wave Processes

When CoolSpan TECA film is used alongside conventional SMD adhesive for mixed-technology boards—PTFE RF sections bonded with TECA, while standard SMD components on FR-4 sections are held with dispensed adhesive for wave soldering—you need to estimate adhesive volume for the wave-solder side independently. Enter your board dimensions and component count below to calculate the dispensed SMD adhesive needed for the wave-soldering portion of a hybrid RF/digital assembly.

For a typical 100 × 80 mm mixed-technology board carrying 120 wave-soldered SMD components, the calculator returns roughly 0.8–1.2 mL of dispensed adhesive. That figure covers only the digital/low-frequency section; the RF substrate bonded with CoolSpan TECA film uses film adhesive cut to shape, not dispensed dots, so the two adhesive budgets are tracked separately in your BOM.

CoolSpan TECA vs. Alternative Bonding Methods

Choose CoolSpan TECA film when you need a lamination-compatible, void-free thermal bond that preserves RF performance and survives thermal cycling without the process complexity of solder reflow. Choose solder preforms when the absolute lowest thermal resistance is required and the assembly can tolerate a reflow step with flux residue management. Avoid standard prepreg in any thermal-critical RF path—its 0.3 W/m·K conductivity creates a thermal bottleneck that no amount of via stitching fully overcomes.

Stackup Integration Tips

• Model the Dk explicitly. At Dk ≈ 4.0, a 1.5 mil CoolSpan layer shifts the effective Dk of a microstrip stackup built on RO4350B (Dk 3.48) by a small but non-zero amount. Run your impedance solver with the adhesive layer included.
• Match CTE where possible. CoolSpan’s z-axis CTE (~30 ppm/°C) sits between copper (17 ppm/°C) and PTFE laminates (50–70 ppm/°C in z). For Taconic TLY-5 PTFE boards, this intermediate CTE reduces interfacial stress compared with a rigid solder bond.
• Keep the film away from plated holes. If vias pass through the bond area, drill and plate after lamination. Drilling through cured CoolSpan film is possible with standard carbide bits, but the conductive filler can smear—use a plasma de-smear cycle.
• Edge-seal against moisture. The film itself has low moisture absorption (< 0.2%), but the interface between film and laminate can wick moisture under humid storage. Apply a conformal coat or hermetic seal at board edges for space and military applications per IPC-6012 Class 3/A requirements.

Storage and Shelf Life

Uncured CoolSpan TECA film ships refrigerated (−18 °C / 0 °F) with a typical shelf life of 6 months. At room temperature, the B-stage resin advances within days, reducing flow and peel strength. Always verify the manufacture date and store per Rogers’ CoolSpan handling guidelines. Once removed from cold storage, allow the sealed bag to reach room temperature before opening to prevent condensation on the film surface.

Frequently Asked Questions

Is CoolSpan TECA film electrically conductive?

Yes—the standard TECA variant is both thermally and electrically conductive, with volume resistivity below 0.006 Ω·cm. Rogers also offers a thermally conductive but electrically insulating version (CoolSpan TECA-I) for applications where the adhesive must not short adjacent signal layers.

Can CoolSpan TECA film bond dissimilar metals?

It bonds well to copper, aluminum, copper–molybdenum (CuMo), and copper–tungsten (CuW) carriers, provided surfaces are properly cleaned and micro-etched. Stainless steel and nickel-plated surfaces also work but may need a chromate or silane coupling treatment for full peel strength.

What is the maximum operating frequency for CoolSpan TECA film?

Rogers characterizes the film through 40 GHz, and it has been used in production assemblies at 77 GHz automotive radar frequencies. At millimeter-wave bands, the thin bond line (1.5 mil) keeps the electrical length through the adhesive short enough that its higher Dk has minimal impact on transmission-line performance.

Does CoolSpan TECA film meet aerospace outgassing requirements?

The cured film exhibits low outgassing consistent with space-grade materials. Designers targeting NASA or ESA missions should request lot-specific TML (total mass loss) and CVCM (collected volatile condensable material) data from Rogers and verify compliance with ASTM E595.

How does CoolSpan TECA film compare to Taconic FastRise 27 bonding layers?

FastRise 27 is a low-Dk laminate, not a thermally conductive adhesive. It serves a different purpose—signal propagation—whereas CoolSpan TECA film is a bonding and thermal-management material. The two can coexist in the same stackup: FastRise 27 as the signal dielectric, CoolSpan TECA film as the substrate-to-heatsink bond.