Issue link: https://iconnect007.uberflip.com/i/1531663
72 PCB007 MAGAZINE I JANUARY 2025 New Ultra HDI Materials Happy's Tech Talk #37 by Happy Holden, I-CONNECT007 Some new materials have been introduced in the past year for ultra high density intercon- nect (UHDI), a convenient title for developing high density technologies. ey have received labels like semiconductor-like PCBs (SLPs), redistribution layers (RDL), flip-chip ball grid array (FCBGA), and interposers. e early 2000s saw the creation of these organic substrates for flip-chip IC packaging. e initial construction was composed of a BT core with build-up layers of the Ajinomoto Build-up Film (ABF) (Table 1). First UHDI Material Engineers perfected the first high-volume flip-chip organic packaging using new vac- uum-laminated thermoset resin films from Aji- nomoto (Table 1) in densities of 8–12-micron traces/spaces. The larger geometr ies of 25–75-micron t/s used more conventional Table 1: Initial nine ABF films from Ajinomoto used for the past 20 years 1 .