Abstract: A radiation sensitive resin composition comprising:(A) an alkali-soluble copolymer comprising:(a) 10 to 50% by weight of a first unit consisting of a radical polymerizable compound having a carboxylic group,(b) 20 to 60% by weight of a second unit consisting of a radical polymerizable compound having a cycloalkyl group, the unit containing no carboxyl group, and(c) 5 to 40% by weight of a third unit consisting of a radical polymerizable compound other than the radical polymerizable compounds in (a) and (b) above;(B) a polymerizable compound having at least one ethylenically unsaturated double bond; and(C) a radiation sensitive radical initiator. Also is disclosed a material for forming bumps containing the radiation sensitive resin composition. The radiation sensitive resin composition has sufficient developability with an alkali developer and sufficient resolution when the composition is in the form of a 20 .mu.m or more thick film.

Abstract: A process for producing a polybutadiene, which comprises polymerizing 1,3-butadiene in an inert organic solvent with a catalyst comprising (A) a cobalt compound, (B) an organoaluminum compound consisting essentially of an aluminoxane and, if necessary, (C) a tertiary phosphine compound, (D) at least one compound selected from the group consisting of an ester compound, an alcohol compound, a phenolic compound, a sulfoxide compound, a nitrogen-containing heterocyclic compound, water and a tertiary amine compound and (E) at least one compound selected from the group consisting of carbon disulfide, a xanthogen compound and a thioisocyanide. By this process, there can be produced, as desired, a cis-1,4-polybutadiene, a 1,2-polybutadiene having a desired vinyl content, a crystalline 1,2-polybutadiene or a polybutadiene containing crystalline 1,2-polybutadiene segments.