A composite material includes: carbon fibers having an average fiber length of more than about 10 mm and about 100 mm or less; and a thermoplastic resin. After termination of the introduction of a dehydrogenation feed into the dehydrogenation reactor that is operated under dehydrogenation reaction conditions, a first cooling fluid comprising steam is introduced into the reactor for a first time period sufficient to cool the dehydrogenation catalyst contained in the dehydrogenation reactor to a second temperature. Furthermore, because the seed layer is ultra thin, the metal bumps or the circuit lines formed on the package substrate can be made finer in line widths and line pitches, and the good yield of the package substrate with fine circuit lines can be increased. The inner core has an outer surface and comprises an electrically conductive core material.