Patent ID: 11920012
Assignee: KOBAYASHI & CO., LTD.
Field: Other special machines (Mechanical engineering)
Classification: CPC C  B  H | IPC B  C  H

Claim 8:
9. A method of manufacturing a release film for use in sealing a semiconductor with a resin, the method comprising:
a first applying step of applying an acrylic resin composition or a siloxane resin composition onto one face of a base layer formed of a polyethylene terephthalate resin;
a first curing step of curing the resin composition applied in the first applying step to give an oligomer bleeding prevention layer;
after the first curing step, a second applying step of applying a fluororesin composition onto the oligomer bleeding prevention layer and an other face of the base layer; and
after the second applying step, a second curing step of curing the fluororesin composition to give surface layers,
wherein a fluororesin that forms the surface layers in the second applying step is a cured product of the fluororesin composition, the fluororesin composition contains a reactive functional group-containing fluoropolymer and a curing agent, the reactive functional group-containing fluoropolymer is a hydroxy group-containing tetrafluoroethylene polymer, and the curing agent is an isocyanate curing agent,
the fluororesin that forms at least one of the surface layers comprises particles having an average particle size of 1 μm to 10 μm determined by laser diffraction particle size analysis,
the content of the curing agent in the fluororesin composition is 15 parts by mass to 50 parts by mass relative to 100 parts by mass of the reactive functional group-containing fluoropolymer, and
the content of the particles in the fluororesin composition is 10 parts by mass to 30 parts by mass relative to 100 parts by mass of the reactive functional group-containing fluoropolymer.