Optimizing the loss rate of UL electronic wire in high-frequency signal transmission requires coordinated efforts from three aspects: material selection, structural design, and process control. The core focus is on reducing conductor loss, dielectric loss, and radiation loss, while also suppressing the impact of skin effect and proximity effect on signal integrity.
Optimizing conductor materials is fundamental to reducing losses. In high-frequency signal transmission, the skin effect causes current to concentrate on the conductor surface, reducing the effective conductive area and significantly increasing resistance. UL electronic wire requires low-resistivity conductors, such as high-purity oxygen-free copper or silver alloys. Their electrical conductivity is much higher than that of ordinary copper, reducing heat loss during high-frequency current flow. Furthermore, conductor surface roughness significantly affects losses. Rough surfaces extend the current path and increase DC and AC resistance. Using very low-profile copper foil (VLP) or reversed-copper foil (RTF) to maintain a surface roughness below 0.2μm can effectively reduce conductor losses.
The choice of dielectric material directly affects dielectric loss. Under high-frequency electric fields, the degree of energy loss is determined by the matching of the polarization frequency of the dielectric molecules with the signal frequency. UL electronic wire requires insulating materials with low dielectric constants (Dk) and low dissipation factors (Df), such as polytetrafluoroethylene (PTFE) or ceramic-filled polyimide. These materials can achieve Df values as low as 0.001, compared to the 0.02 of standard FR-4 material, reducing dielectric loss by 80% at 10 GHz. Furthermore, impurity levels in the dielectric, such as moisture and metal ions, must be strictly controlled to prevent additional losses caused by impurities.
Transmission line structure design is key to controlling impedance and reducing radiation. The structural differences between microstrip, stripline, and coplanar waveguide directly impact signal transmission characteristics. Microstrip, due to its semi-open structure, is susceptible to external interference and exhibits high radiation loss. Stripline routing on inner layers can reduce radiation, but requires stringent fabrication precision. Coplanar waveguide utilizes ground conductor strips to suppress crosstalk and is suitable for millimeter-wave frequencies. UL electronic wire requires selecting the appropriate structure based on the operating frequency band and maintaining a stable impedance (typically 50Ω) by precisely controlling transmission line width, dielectric layer thickness, and spacing. For example, in the 28 GHz frequency band, the differential trace spacing needs to be adjusted to 2-3 times the trace width to balance impedance and proximity effect.
Skin effect and proximity effect mitigation require process optimization. The skin depth of high-frequency current decreases with increasing frequency, from approximately 2 μm at 1 GHz to only 0.38 μm at 28 GHz. UL electronic wire requires thin copper foil (18-35 μm) to cover the skin layer, avoiding excessive thickness that wastes material or excessive thinness that cannot carry current. Regarding proximity effect, magnetic field coupling between differential traces can exacerbate losses. This can be mitigated by installing ground shields or increasing trace spacing. For example, increasing the 28 GHz differential trace spacing from 0.15 mm to 0.3 mm can reduce proximity effect losses by 20%.
Controlling radiation loss requires careful attention to trace continuity and grounding design. Structures such as right-angle traces and vias can cause impedance abrupt changes, leading to signal reflection and radiation. UL electronic wire should use curved transitions instead of right-angle traces and reduce the number of vias. Ground plane integrity is also critical. Excessive gaps or via spacing can extend the signal return path and increase radiation. Connecting ground straps at multiple points and optimizing via layout can significantly reduce radiation loss.
The impact of environmental factors on UL electronic wire loss cannot be ignored. Rising temperatures increase conductor resistance and dielectric loss, while increased humidity can cause the dielectric to absorb moisture, increasing the Df value. For example, moisture absorption in a PTFE substrate increases the Df value from 0.001 to 0.003, increasing the loss of a 100mm line by 0.6dB at 10GHz. Therefore, UL electronic wire should be stored in a dry environment and sealed in sealed packaging to prevent moisture absorption.
Full-chain optimization, from materials to processes, is key to reducing high-frequency losses in UL electronic wire. By selecting low-loss conductors and dielectrics, designing appropriate transmission structures, suppressing skin and proximity effects, and controlling radiation and environmental impacts, signal transmission efficiency can be significantly improved, meeting the stringent requirements of high-frequency applications such as 5G and millimeter-wave radar.
