MAGTREX 555 is a magneto-dielectric thermoplastic composite rather than an ordinary nonmagnetic PCB substrate. Both its permittivity and permeability affect electromagnetic propagation. The material is relevant to electrically small VHF/UHF antenna concepts and loading structures where magnetic response is part of the intended design.
Material system
Magnetic ceramic filler in a high-temperature thermoplastic matrix
Technical properties
| Property | Reported value | Conditions / source |
|---|---|---|
| Dissipation factor | 0.01 | Typical dielectric loss tangent in X/Y at 400 MHz; 1-inch coaxial airline, NRW extraction. Magnetic loss is a separate quantity and is not included. Source |
| CTE, X axis | 22 ppm/°C | Typical; -55°C to 288°C, IPC-TM-650 2.4.41; average expansion over the interval, not necessarily linear. Source |
| CTE, Y axis | 25 ppm/°C | Typical; -55°C to 288°C, IPC-TM-650 2.4.41; average expansion over the interval, not necessarily linear. Source |
| CTE, Z axis | 25 ppm/°C | Typical; -55°C to 288°C, IPC-TM-650 2.4.41; average expansion over the interval, not necessarily linear. Source |
| Process dielectric constant | 6.5 | Typical permittivity, X/Y, 400 MHz; 1-inch coaxial airline, NRW extraction. Magnetic material; not an ordinary impedance-model input. Source |
| Process dielectric constant | 5.3 | Typical permittivity, Z direction, 400 MHz; FSR, IPC-TM-650 2.5.5.6. A different direction and method from the in-plane value. Source |
| Density | 3.45 g/cm³ | Typical; C-24/23/50, ASTM D792 Method A. Source |
| Water absorption | <0.25 % | Typical; D48/50, IPC-TM-650 2.6.2.1. Source |
Typical reported values are not a purchase specification. Process Dk, design Dk and values measured at different frequencies are not interchangeable.
Selection and design notes
- Evaluate it with a model that accepts complex, frequency-dependent permittivity and permeability, including directional data. The product sheet reports in-plane permittivity 6.5 and permeability 6.0 at 400 MHz by coaxial-airline NRW extraction; its Z-axis dielectric observation uses another method.
- A miniaturization estimate must also account for magnetic loss and bandwidth. Treating the product of dielectric and magnetic values as an ordinary laminate Dk would hide the relevant physics.
Thickness and copper options
The sheet lists clad or unclad thicknesses from 40 to 260 mil in specified steps; confirm the selected mechanical configuration.
1 oz ED copper or unclad material is offered. A magnetic loading element may not require copper at all.
Fabrication considerations
- Specify whether the material is clad or unclad and review machining, mounting and any bonding approach with the manufacturer. Loading elements and etched circuit laminates impose different geometric and manufacturing requirements.
Application fit
- Electrically small VHF/UHF antennas
- Magnetic loading elements
- VHF magnetic components
Limits and substitution checks
- This record is excluded from ordinary impedance presets. The approximately +1000 ppm/°C selector coefficient concerns the square root of permittivity times permeability, not Dk alone. The source curves are essential near magnetic dispersion; a single 400 MHz observation cannot describe arbitrary frequencies.