Patent ID: 6660943
Filing Date: 2003-12-09
Classification: H01L,H05K,Y02P,Y10T

Abstract:
A mounted board comprising a circuit board and a semiconductor package holding semiconductor elements on a carrier substrate, wherein said semiconductor package is connected to said circuit board with solder balls, and spaces between solder connected parts are filled with an underfilling material which consists essentially of a on-pack type thermosetting urethane composition comprising:a urethane prepolymer having a terminal isocyanate group, which is obtained by reacting a polyol with an excessive amount of a polyisocyanate, wherein said urethane prepolymer is a mixture of a urethane prepolymer having a terminal isocyanate group comprising a hydrocarbon polyol as a polyol and a urethane prepolymer having a terminal isocyanate group comprising a polyoxyalkylene polyol in a weight ratio of 9:1 to 2:8, and a fine powder-coated curing agent comprising a curing agent which is in a solid state at room temperature and surface active sites of which are covered with a fine powder.