Issue link: https://iconnect007.uberflip.com/i/1531663
74 PCB007 MAGAZINE I JANUARY 2025 thin laser drillable (LD) laminates, pre- pregs, and resin-coated foil (RCC/ RCF)1. Because controlled impedance is required for these boards, many new UHDI materials are unreinforced resin films, such as the one shown in Figure 1. Newer UHDI Materials Besides new RCCs and RCFs, there are supported film and liquid resins that provide bonding for various thin build- up dielectrics. Newer UHDI materials are from AGC Multi-Material America Inc. Tables 2 through 6 2 present some of the thin materials. e AGC products start with various thin copper foils from 1.5, 2, 3, 5, up to 18 microns, as seen in Table 2. Table 2: AGC selection of low-profile Cu foils for unsupported resins 2 Table 3: Resin properties of the thin, fastRise™ TC/HF films 2 Figure 1: New resin-coated foil from Ajinomoto, with only 1 µm of copper, conveyorized vacuum lamination, and 60-minute post-cure, results in a finished UHDI with a buried via core. (Source: Ajinomoto)