| abstract |
Provided is a mask sheet capable of stably producing a semiconductor package such as QFN by suppressing protruding of the resin sealant and residual adhesive of the pressure sensitive adhesive during assembly of the semiconductor device. This mask sheet is detachably bonded to the lead frame, and forms an adhesive layer made of a silicone-based adhesive on a heat-resistant film having a glass transition temperature of 150 ° C. or higher and a linear expansion coefficient of 10 to 50 ppm / ° C. at 150 to 200 ° C. It is made and the weight reduction rate when it heats at 180 degreeC for 1 hour is 5% or less. As a silicone type adhesive, it is preferable to have a polydimethylsiloxane as a main component, and to have a polyalkyl alkenylsiloxane and polyalkyl hydrogensiloxane as a main component. When using this mask sheet for the assembly of a semiconductor device, a mask sheet is crimped | bonded to a lead frame first, and a semiconductor device is formed and peeled off. |