Abstract: A first aspect of the present invention is carbon fiber wherein the surface of a monofilament has a center line average roughness Ra of 6.0 nm or more and 13 nm or less, and the monofilament has a long diameter/short diameter ratio of 1.11 or more and 1.245 or less. A second aspect of the present invention is carbon fiber precursor acrylic fiber wherein the surface of a monofilament has a center line average roughness Ra of 18 nm or more and 27 nm or less, and the monofilament has a long diameter/short diameter ratio of 1.11 or more and 1.245 or less. The carbon fiber according to the first aspect is obtained by stabilizing and carbonizing under specific conditions the carbon fiber precursor acrylic fiber according to the second aspect.

Abstract: A sizing agent for carbon fiber includes component (A), component (B), and component (C), in which the component (A) is at least one selected from the group consisting of component (A-1), component (A-2), and component (A-3); the component (A-1) is a urethane compound having a structure of Formula (1-1) in the molecule, the component (A-2) is an ester compound having a structure represented by Formula (1-2) in the molecule, the component (A-3) is an amide compound having a structure of Formula (1-3) in the molecule; the component (B) is an epoxy compound selected from the group consisting of an epoxy compound represented by Formula (2), an epoxy compound represented by Formula (3), and an epoxy compound represented by Formula (4); and the component (C) is a bisphenol type epoxy compound.

Abstract: A chopped carbon fiber bundle comprising carbon fibers and a sizing agent, the sizing agent including a compound having a maleimide group, the compound having a maleimide group being liquid at 25° C. A method for producing a chopped carbon fiber bundle, the method comprising a step of applying an aqueous dispersion of a secondary sizing agent including a compound having a maleimide group to a long-length carbon fiber bundle including a primary sizing agent deposited thereon, in order to prepare a long-length carbon fiber bundle further including the aqueous dispersion of the secondary sizing agent, and a step of cutting the long-length carbon fiber bundle including the aqueous dispersion of the secondary sizing agent. A chopped carbon fiber bundle that has improved. heat resistance and. feedabli and that is capable of beng produced with high productivity is provided.

Abstract: Use of a sizing agent having a heat weight loss B-1 of 65% or more as determined by a specific measurement method, or a sizing agent containing a surfactant and a compound represented by formula (1):

Abstract: A sizing agent is provided, the sizing agent being blended with a component (A) and a component (B), wherein a mass ratio A/B of the component (A) to the component (B) is 0.5 to 20, and a proportion of a total mass of the component (A) and the component (B) with respect to a total mass of the sizing agent is 80% by mass or more, wherein the component (A) is an epoxy resin having a viscosity of 1 to 180,000 Pa·s at 30° C., and the component (B) is an aliphatic ester compound having a freezing point of 50° C. or lower.

Abstract: A first aspect of the present invention is carbon fiber wherein the surface of a monofilament has a center line average roughness Ra of 6.0 nm or more and 13 nm or less, and the monofilament has a long diameter/short diameter ratio of 1.11 or more and 1.245 or less. A second aspect of the present invention is carbon fiber precursor acrylic fiber wherein the surface of a monofilament has a center line average roughness Ra of 18 nm or more and 27 nm or less, and the monofilament has a long diameter/short diameter ratio of 1.11 or more and 1.245 or less. The carbon fiber according to the first aspect is obtained by stabilizing and carbonizing under specific conditions the carbon fiber precursor acrylic fiber according to the second aspect.

Abstract: A sizing agent for carbon fiber includes component (A), component (B), and component (C), in which the component (A) is at least one selected from the group consisting of component (A-1), component (A-2), and component (A-3); the component (A-1) is a urethane compound having a structure of Formula (1-1) in the molecule, the component (A-2) is an ester compound having a structure represented by Formula (1-2) in the molecule, the component (A-3) is an amide compound having a structure of Formula (1-3) in the molecule; the component (B) is an epoxy compound selected from the group consisting of an epoxy compound represented by Formula (2), an epoxy compound represented by Formula (3), and an epoxy compound represented by Formula (4); and the component (C) is a bisphenol type epoxy compound.

Abstract: A semiconductor device is provided with an electrode pad; and a lower layer arranged under the electrode pad. The electrode pad includes a slit section, penetrating a whole thickness of the electrode pad from a higher surface to a lower surface in contact with the lower layer; a contact start region, arranged in the higher surface, on which a probe makes a contact; and an inspection region, arranged in the higher surface, on which the probe makes an inspection upon the semiconductor. The slit section includes a first group of aperture open to the inspection region; a second group of aperture open to the contact start region smaller than the first group of aperture; and a vacant region able to store a part of shavings produced by the probe while shifting from the contact start region to the inspection region, by grinding the higher surface of the electrode pad.

Abstract: A hybrid integrated circuit device is provided which suppresses lowering of the inductance value of a mounted coil component. A hybrid integrated circuit device according to the present invention has such a structure that a wiring pattern is provided on at least one main face of a substrate, a laid core type coil component is mounted on at least one main surface of the substrate, and a conductor pattern including a ground pattern is provided at least either on a main face opposite to the surface of the substrate upon which the laid core type coil component is mounted or in an interior of the substrate. In particular, the hybrid integrated circuit device has a configuration such that a magnetic flux passing window, having an absence of ground pattern, is provided in an orthographic projection area corresponding to a winding portion of the coil component in the conductor pattern.