To provide a porous resin having high heat resistance, dimensional stability, and insulating property, and having uniform micropores, a photosensitive resin composition for obtaining the porous resin, and a circuit board and a suspension substrate with a circuit each having such a porous resin as an insulating layer.
The photosensitive resin composition 2 comprises a polybenzoxazole precursor 4 having a repeating unit structure of formula (1), a photosensitive agent, a dispersible compound 3 and a solvent. The porous resin is obtained as follows; the solvent is removed from the photosensitive resin composition 2 to form a state in which the dispersible compound 3 is dispersed in the polybenzoxazole precursor 4, the compound 3 is then removed to make the precursor 4 porous, and the precursor 4 is hardened. Since the porous resin has a low dielectric constant, when it is used as an insulating layer 6 in a circuit board, the high-frequency characteristics of the circuit board can be improved.
FUKUOKA TAKAHIRO
KANESHIRO NAOTAKA
KONDO TAKASHI
