Meaning
Electromagnetic attenuation in dielectric and conductive pathways measures the dissipation of electrical signal energy at high operating frequencies. The high frequency conduction loss determines the rate at which power is converted to heat as signal currents travel through molded interconnect devices or microstrip lines. This property restricts the signal integrity of high frequency electronic enclosures.
Material Selection
Polymer formulations with specific dielectric properties are required to minimize signal degradation in telecommunication components. When choosing resin matrices for radar or high speed antennas, high frequency conduction loss represents a major selection criterion. High performance thermoplastics must maintain low loss tangents to prevent the thermal dissipation of transmitted waves.
Surface Roughness
Molded part surface finishes dictate the path length of high frequency electrical currents. The skin effect forces current to flow near the outer boundary of the conductor, meaning that high frequency conduction loss increases significantly when mold surfaces transfer a rough texture to the molded interconnect lines. Highly polished tool steel inserts are therefore utilized to produce smooth surfaces that facilitate efficient electrical propagation.
Thermal Management
Operating temperatures of electronic assemblies depend heavily on the efficiency of the internal circuitry. Excessive high frequency conduction loss generates localized heating within the polymer housing, which can lead to thermal degradation of the plastic. This localized thermal stress alters the dielectric constant of the material, creating a negative feedback loop that further degrades signal transmission.
Engineers must use conductive fillers or optimize cooling geometry to dissipate this heat before it compromises the structural integrity of the device housing.
