Abstract: This plating liquid contains (A) a soluble salt that contains at least a stannous salt, (B) an acid selected from organic acids and inorganic acids or a salt thereof, and (C) two kinds of surfactants of an amine-based surfactant (C1) and a nonionic surfactant(s) (C2 and/or C3). The amine-based surfactant (C1) is a polyoxyethylene alkyl amine represented by general formula (1); and the nonionic surfactant(s) (C2 and/or C3) is a condensation product of a polyoxyethylene and a polyoxypropviene represented by general formula (2) or general formula (3). In formula (1), x is 12-18 and y is 4-12. In formula (2), m is 15-30 and (n1+n2) is 40-50. In formula (3), (m1+m2) is 15-30 and n is 40-50.

Abstract: This plating liquid contains (A) a soluble salt that contains at least a stannous salt, (B) an acid selected from organic acids and inorganic acids or a salt thereof, and (C) two kinds of surfactants of an amine-based surfactant (C1) and a nonionic surfactant(s) (C2 and/or C3). The amine-based. surfactant (C1) is a polyoxyethylene alkyl amine represented by general formula (1); and the nonionic surfactant(s) (C2 and/or C3) is a condensation product of a polyoxyethylene and a polyoxypropviene represented by general formula (2) or general formula (3). In formula (1), x is 12-18 and y is 4-12. In formula. (2), m is 15-30 and (n1+n2) is 40-50. In formula. (3), (m1+m2) is 15-30 and n is 40-50.

Abstract: A clamp mechanism comprises a turntable, a plurality of chuck claws, and a driving element. The turntable is rotatably driven by a motor. A disc serving as a recording medium is placed on the turntable. The chuck claws are used to hold, that is, clamp the disc on the turntable. The driving element drives the chuck claws both in both a first direction determined to clamp the disc and a second direction determined to unclamp the disc. The driving element includes a pressing portion so that travel of the chuck claws in the first direction in cases where the chuck claws are driven in the second direction. This offers stable clamping and unclamping operations of the chuck claws to detachably hold the disc on the turntable, independently of which attitude the disc takes.

Abstract: A clamp mechanism comprises a turntable, a plurality of chuck claws, and a driving element. The turntable is rotatably driven by a motor. A disc serving as a recording medium is placed on the turntable. The chuck claws are used to hold, that is, clamp the disc on the turntable. The driving element drives the chuck claws both in both a first direction determined to clamp the disc and a second direction determined to unclamp the disc. The driving element includes a pressing portion so that travel of the chuck claws in the first direction in cases where the chuck claws are driven in the second direction. This offers stable clamping and unclamping operations of the chuck claws to detachably hold the disc on the turntable, independently of which attitude the disc takes.

Abstract: A clamp unit for a disk comprises a disk table on which a disk is mounted and a clamper disposed in association with the disk table for clamping the disk under pressure therebetween. A film is formed on a surface of either one of the disk table and the clamper and formed of a mixture a synthetic resin and a plurality of fine particles disposed in the synthetic resin, both having viscous and elastic property, and some of the particles are exposed outside an outer surface of the film so as to provide an irregular surface having protruded portions.