Mid Loss Laminates That Outrun Their Price Class
Mid-loss laminates paired with low-roughness copper foil match high-cost ultra-low-loss performance at a fraction of the raw panel price.
Signal Insertion Loss
Transmission Loss
Signal power in a transmission line declines as it travels from the transmitter to the receiver due to several physical dissipation mechanisms. The signal insertion loss is the total reduction in signal amplitude along a high speed circuit trace, typically measured in decibels per unit length at a given frequency. This loss determines the maximum length of a trace that can be routed on a board before the signal becomes too degraded for the receiver to detect.
Designers measure this loss using network analyzers and use it as the main performance metric for high frequency layouts.
Conductor Effect
Conductor resistive loss and dielectric absorption are the two main physical phenomena that cause this reduction in signal power. When signal insertion loss occurs, high frequency currents travel in the skin depth of the conductor, where any surface roughness on the copper trace increases the resistance. Simultaneously, the alternating electromagnetic field causes the polymer molecules in the surrounding dielectric substrate to polarize, which converts some of the electrical energy into heat.
Using smoother copper foil and low loss substrates is a standard method to minimize both of these loss mechanisms.
Dielectric Solution
Trace geometry also plays a role in determining the total loss. Wider traces have lower resistance and therefore experience less conductor loss than narrower traces. However, because wider traces must be paired with thicker dielectric layers to maintain a fifty ohm impedance, the layout must be optimized to balance trace width, dielectric loss, and board thickness.