| abstract |
(57) [Problem] To bond an electronic component and an electronic circuit board without flux cleaning. An underfill material is filled in a gap between a CSP and an electronic circuit board on which the CSP is mounted, and the CSP is bonded to the electronic circuit board. The thermosetting polyurethane composition used for the underfill material 14 has, in addition to the terminal isocyanate group-containing urethane prepolymer and epoxy resin, an organopolysiloxane compound, a bleed inhibitor, and a silane coupling agent. Thereby, even when the electronic circuit board 11 is subjected to flux treatment, permeation of the underfill material 14 is not hindered and flux cleaning becomes unnecessary. Furthermore, this thermosetting polyurethane composition has a strong adhesive force, is softened at a low temperature, and recovers the adhesive force even after being softened, so that electronic parts can be easily repaired. |