Terahertz Characterization of Glass-Based Materials and Stackups for 6 G Microelectronics Packaging

Glass-based materials, including polymer/glass stack ups, are attractive structural blocks for packaging substrates supporting 5 G and 6 G microelectronic modules and components. We present the first broadband characterization of AGC Inc. EN-A1 alkali-free boroaluminosilicate glass and of Ajinomoto Build-up Film (ABF) laminated on soda-lime float glass substrate from 200 GHz to 2.5 THz with a commercial terahertz time-domain spectroscopy (THz-TDS) system. The refractive index n(ν) , attenuation coefficient α(ν) , permittivity ε^′(ν) , and loss tangent tan δ(ν) of EN-A1 glass as well as laminated ABF are n_{EN - A 1}= 2.376 , α_{EN - A 1}= 31.1 cm ^{- 1} , εEN-A1′=5.64 , tan δ_{EN - A 1}= 0.062 , and n_ABF= 1.9 , α_ABF= 30 cm ^{- 1} , ε_ABF= 3.8 , tan δ_ABF= 0.072 , all at 1 THz. Our results validate the promising perspective of both EN-A1 glass and ABF polymer materials as microwave and THz packaging solutions.