Abstract: The present invention has the object of increasing the heat exchanging performance of heat transfer tubes having grooved inner surfaces. In order to achieve this object, the heat transfer tubes having grooved inner surfaces according to the present invention have fins which are formed consecutively in a circumferential direction on the inner surface of a metallic tube. The inner surface of the metallic tube is divided into regions R1.about.R4 in the circumferential direction. The inclination angle .alpha. with respect to the axis of the heat transfer tube of the fins 2 in odd-numbered regions when counting from one of the regions is 10.about.25.degree., and the inclination angle .beta. with respect to the axis of the heat transfer tube of the fins 2 in even-numbered regions when counting from the region is -10.about.-25.degree.. The pitch of the fins 2 is 0.3.about.0.4 mm, the height of the fins from the inner circumferential surface of the metallic tube is 0.15.about.0.

Abstract: The present invention has the object of increasing the heat exchanging performance of heat transfer tubes having grooved inner surfaces. In order to achieve this object, the heat transfer tubes having grooved inner surfaces according to the present invention have fins which are formed consecutively in a circumferential direction on the inner surface of a metallic tube. The inner surface of the metallic tube is divided into regions R1.about.R4 in the circumferential direction. The inclination angle .alpha. with respect to the axis of the heat transfer tube of the fins 2 in odd-numbered regions when counting from one of the regions is 10.degree..about.25.degree., and the inclination angle .beta. with respect to the axis of the heat transfer tube of the fins 2 in even-numbered regions when counting from the region is -10.degree..about.-25.degree.. The pitch of the fins 2 is 0.3.about.0.4 mm, the height of the fins from the inner circumferential surface of the metallic tube is 0.15.about.0.

Abstract: A lead frame material comprises a base plate consisting of copper or copper alloys, and a protective coating formed on the upper or the both surface of the base plate. The protective coating is composed of at least one metal selected from the group consisting of gold, gold alloy, silver, silver alloy, palladium and palladium alloy, and has a thickness of 10-500 angstrom. The protective coating is formed by means of vapor deposition. It is possible to form an intermediate coating of nickel or nickel alloys between the surface of the base plate and the protective coating, by means of vapor deposition or wet plating. The suitable thickness of the intermediate coating is within the range of 50-20000 angstrom.

Abstract: The heat transfer tube of the present invention is provided in an inner surface thereof with a plurality of main grooves and a plurality of narrow grooves. The main grooves have rectangular shaped cross sections, parallel to one another, and extend at an angle to the longitudinal direction of the heat transfer tube. The narrow grooves are formed parallel to one another, extend independently of the main grooves. Each of the narrow grooves has a bottom face and a pair of side faces, the side faces are inclined closely toward the bottom face, and each of the side faces and a part of the bottom face form sharp cuts.

Abstract: A heat transfer tube having an inner surface in which are formed primary grooves and secondary grooves. The primary grooves parallel to one another, extending at an angle to the longitudinal direction of the heat transfer tube and secondary grooves parallel to one another, extending an angle to the primary grooves. At the intersections of the primary and secondary grooves is formed a series of pear-shaped grooves whose inner opening dimension is smaller than the dimension of the bottom of the pear-shaped groove.