High-Dk 2-Layer Design Using Rogers TMM10

In high-frequency circuit design, certain applications demand a dielectric constant significantly higher than standard microwave laminates. Chip testers, GPS patch antennas, satellite communication systems, and dielectric polarizers all benefit from materials with Dk values approaching 10—enabling circuit miniaturization, improved antenna gain, and specific phase response characteristics.

This article examines a 2-layer PCB implementation utilizing Rogers TMM10—a thermoset microwave laminate that bridges the gap between PTFE and ceramic-based substrates. The design features a 15mil (0.381mm) core with a finished thickness of 0.5mm, optimized for applications requiring high dielectric constant with robust mechanical properties.

1. Design Overview and Specifications

This double-sided rigid PCB measures 76mm x 118mm and utilizes a TMM10 core with a nominal Dk of 9.20—substantially higher than standard RF materials like RO4003C (Dk 3.38) or RO4533 (Dk 3.3). The table below summarizes the key construction parameters and design statistics.

Stackup Configuration: The 2-layer stackup consists of a TMM10 core (0.381mm / 15mil) sandwiched between two 1 oz copper layers, resulting in a finished board thickness of 0.5mm.

2. TMM10 Material Properties

Rogers TMM series materials occupy a unique position in the microwave laminate market. Unlike PTFE-based substrates, which are thermoplastic and prone to creep and cold flow under mechanical stress, TMM materials utilize a thermoset resin system. The table below presents the key electrical, thermal, and mechanical properties of TMM10.

The CTE of TMM10 is closely matched to copper in all three axes (21/21/20 ppm/°C vs. copper's 17 ppm/°C). This exceptional match minimizes thermo-mechanical stress on plated through-holes—critical for the 32 thru-hole pads and 24 vias in this design. The decomposition temperature of 425°C significantly exceeds standard lead-free soldering temperatures (260°C), providing a substantial safety margin during assembly.

3. Application Suitability

Given its high Dk, low loss, and mechanical robustness, this 2-layer TMM10 design is ideally suited for the following applications:

Chip Testers / Semiconductor Test Hardware

Dielectric Polarizers

Satellite Communication Systems

GPS Antennas & Patch AntennasGPS Antennas & Patch Antennas

4. Summary

The 2-layer PCB detailed here demonstrates an optimized implementation of Rogers TMM10 for applications requiring a high dielectric constant without compromising mechanical stability. With a 15mil core (0.5mm finished thickness), 1 oz copper, and ENEPIG surface finish, the design balances RF performance, thermal reliability, and fabricability.

For engineers working on chip testers, satellite communication systems, or compact GPS antennas, TMM10 offers a compelling value proposition: the high Dk (9.20) needed for circuit miniaturization, the low loss (0.0022) required for signal integrity, and the thermoset mechanical properties that eliminate creep, cold flow, and special via preparation processes—all while maintaining CTE match to copper for reliable plated through-hole performance.