| abstract |
Provided is a bump base reinforcement sheet which can reinforce a base portion of even a solder bump having a large diameter on a primary mounted substrate side and achieve good electrical connection with a secondary mounted substrate. A bump base reinforcement sheet includes: a base material sheet; and a thermosetting resin sheet laminated on the base material sheet, in which a thickness t [μm] of the base material sheet and a minimum melt viscosity η [Pa·s] of the thermosetting resin sheet at 50 to 180° C. satisfy the following relational expression: n 150≤ t ·η≤100000. |