| 摘要 |
The present invention relates to a back grinding sheet (BG sheet) (1a, 1b, 1c) having an unevenness absorption layer (12) provided on a substrate (11), said unevenness absorption layer being formed from a film forming composition including (A) urethane (meth)acrylate and (B) a polymerizable monomer other than component (A). Furthermore, the unevenness absorption layer (12) satisfies conditions (a) to (c): (a) that the loss tangent at 70˚C measured using a frequency of 1Hz be at least 1.5; (b) that, after compressing a square of the unevenness absorption layer measuring 1cm x 1cm at a compression load of 10N at 25˚C, the relaxation rate after 300 seconds be 30% or less; and (c) that the storage elastic modulus at 25˚C measured using a frequency of 1Hz be in the range of 1.0-10.0 MPa. This BG sheet exhibits excellent absorption of uneven sections such as bumps or the like present on semiconductor wafers, is capable of inhibiting the formation of gaps between the BG sheet and the bumps or the like, and is capable of inhibiting the phenomenon in which a resin layer (the unevenness absorption layer) of the BG sheet begins to extrude from roll ends when winding the BG sheet into a roll. |
