Abstract: This invention relates to thermosetting resin compositions useful for mounting onto a circuit board semiconductor devices, such as chip size or chip scale packages (“CSPs”), ball grid arrays (“BGAs”), land grid arrays (“LGAs”), and the like, each of which having a semiconductor chip, such as large scale integration (“LSI”), on a carrier substrate, as well as compounds useful in such compositions. The compositions include compounds having a thermally cleavable linkage, and include an episulfide group within the compound. The compositions of this invention are reworkable when subjected to appropriate conditions.