Issue link: https://iconnect007.uberflip.com/i/1460418
36 PCB007 MAGAZINE I MARCH 2022 meet the loss, timing delay, and impedance match requirements of the application. PCB laminates are typically manufactured in two ways: 1. By impregnating and strengthening a woven fiberglass fabric with resin. 2. Reinforcing the resin system with non- woven fibers or alternative fillers to control the coefficient of thermal expansion. In addition to optimal electrical proper- ties, dielectric materials for high speed/fre- quency applications are engineered to exhibit improved thermal reliability, dimensional sta- bility, and low moisture absorption. e resin matrix at the core of these systems has greatly evolved from standard epoxy to olefin chemis- tries which exhibit the desired electrical prop- erties of PTFE-like substrates, but also offer ease of processing and low reliability risk. Figure 1 offers a simplified illustration of these resin chemistry performance targets. In addition to dielectric properties, conduc- tor losses (due to resistivity and skin depth) are important criteria for laminate selection. e surface roughness of copper plays an impor- tant role in increased attenuation observed at the millimeter wave frequencies required for 5G/6G communication. In this regard, cop- Figure 1: Evolution of resin chemistry dielectric properties. Figure 2: Rz measurements showing copper roughness improvements.