Back grinding sheet

摘要

The present invention relates to a back grinding sheet (BG sheet) (1a, 1b, 1c) having an unevenness-absorbing layer (12) on a substrate (11), in which the unevenness-absorbing layer is a layer formed of a film-forming composition containing (A) a urethane (meth)acrylate and (B) a polymerizable monomer except component (A) and the layer satisfies the following requirements (a) to (c): (a) a loss tangent at 70° C. measured at a frequency of 1 Hz is 1.5 or more, (b) a relaxation rate 300 seconds after a square (1 cm×1 cm) of the unevenness-absorbing layer is compressed at 25° C. and a compressive load of 10 N is 30% or less, and (c) a storage elastic modulus at 25° C. measured at a frequency of 1 Hz is 1.0 to 10.0 MPa. The BG sheet of the present invention has excellent absorptivity of uneven portions such as bumps in a semiconductor wafer and can suppress formation of gaps between bumps and the BG sheet and simultaneously suppress a phenomenon where the resin layer (unevenness-absorbing layer) of a BG sheet oozes from the edges of a roll when the BG sheet is wound up in the form of roll.

主权项

1. A back grinding sheet, comprising an unevenness-absorbing layer on a substrate,
wherein: the unevenness-absorbing layer is a layer formed of a film-forming composition comprising
(A) a urethane (meth) acrylate present in an amount of 33% by mass or more, based on a total mass of the film-forming composition,(B) a polymerizable monomer not including the urethane (meth)acrylate (A), and(C) a thiol group-containing compound; and the unevenness-absorbing layer satisfies the following requirements (a) to (c)(a) a loss tangent at 70° C. measured at a frequency of 1 Hz is 1.5 or more,(b) a relaxation rate 300 seconds after a square (1 cm×1 cm) of the unevenness-absorbing layer is compressed at 25° C. and a compressive load of 10N is 30% or less, and(c) a storage elastic modulus at 25° C. measured at a frequency of 1 Hz is 1.0 to 10.0 MPa.