A PCB terminal is provided with a rod-like base material and a plating layer covering a predetermined region of the base material. A constituent material of the base material is a copper alloy containing 20% by mass or more of zinc. The plating layer includes a first coating portion and a second coating portion. The first coating portion includes an entire peripheral layer entirely covering a region on side of a first end part, out of both end parts of the base material, in a circumferential direction of the base material. The second coating portion partially covers a region on side of a second end part, out of the both end parts of the base material, in the circumferential direction of the base material. The entire peripheral layer includes a tin-based layer and a barrier layer.

A method for forming a circuit board having a dielectric core, a foil top surface, and a thin foil bottom surface with a removable foil backing of sufficient thickness to absorb heat from a laser drilling operation to prevent the penetration of the thin foil bottom surface during laser drilling utilizes a sequence of steps including a laser drilling step, removing the foil backing step, electroless plating step, patterned resist step, electroplating step, resist strip step, tin plate step, and copper etch step, which provide dot vias of fine linewidth and resolution.

A Sn-plated steel sheet including a base plated steel sheet having a steel sheet, a Sn-plated layer on at least one surface of the steel sheet, and a film layer containing a zirconium oxide and a tin oxide. An adhesion amount of Sn per surface of the Sn-plated steel sheet is 0.1 g/m.sup.2 or more and 15 g/m.sup.2 or less, an amount of the zirconium oxide in the film layer is in a range of 1 mg/m.sup.2 or more and 30 mg/m.sup.2 or less in terms of an amount of metal Zr, a peak position of a binding energy of Sn3d.sub.5/2 of the tin oxide is 1.4 eV or more and less than 1.6 eV from a peak position of a binding energy of metal Sn, and a quantity of electricity required for reduction of the tin oxide is more than 5.0 mC/cm.sup.2 and 20 mC/cm.sup.2 or less.

An anti-corrosion terminal material including a base material made of copper or copper alloy and a coating film laminated on the base material: the coating film includes: a first coating film, provided with a zinc layer made of zinc alloy and a tin layer made of tin or tin alloy which are laminated in this order, and formed at a planned core contact part; and a second coating film including the tin layer but not comprising the zinc layer, which is provided at a planned contact part being a contact part when the terminal is formed: and the zinc layer has a thickness not less than 0.1 μm and not more than 5.0 μm and zinc concentration not less than 30% by mass and not more than 95% by mass, and has any one or more of nickel, iron, manganese, molybdenum, cobalt, cadmium, lead and tin as a balance.

An anti-corrosion terminal material including a base material made of copper or copper alloy and a coating film laminated on the base material: the coating film includes: a first coating film, provided with a zinc layer made of zinc alloy and a tin layer made of tin or tin alloy which are laminated in this order, and formed at a planned core contact part; and a second coating film including the tin layer but not comprising the zinc layer, which is provided at a planned contact part being a contact part when the terminal is formed: and the zinc layer has a thickness not less than 0.1 μm and not more than 5.0 μm and zinc concentration not less than 30% by mass and not more than 95% by mass, and has any one or more of nickel, iron, manganese, molybdenum, cobalt, cadmium, lead and tin as a balance.

A copper alloy plate containing in a center part of a plate thickness direction more than 2.0% (% by mass) and 32.5% or less of Zn; 0.1% or more and 0.9% or less of Sn; 0.05% or more and less than 1.0% of Ni; 0.001% or more and less than 0.1% of Fe, and 0.005% or more and 0.1% or less of P; and the balance Cu, including a surface layer part in which a surface Zn concentration in a surface is 60% or less of a center Zn concentration in the center part, having a depth from the surface to where Zn concentration is 90% of the center Zn concentration; and in the surface layer, the Zn concentration increases from the surface toward the center part in the plate thickness direction at a concentration gradient of 10% by mass/μm or more and 1000% by mass/μm or less.

A Cu—Ni—Si based copper alloy containing Ni and Si: in a center portion in a plate thickness direction, containing 0.4% by mass or more and 5.0% by mass or less of Ni, 0.05% by mass or more and 1.5% by mass or less of Si, and the balance Cu and inevitable impurities; where an Ni concentration on a plate surface is 70% or less of a center Ni concentration in the thickness center portion; a surface layer portion having a depth from the plate surface to be 90% of the center Ni concentration; in the surface layer portion, the Ni concentration increases from the plate surface toward the thickness center portion at 5.0% by mass/.Math.m or more and 100% by mass/.Math.m or less of a concentration gradient; to improve the electric connection reliability under high-temperature environment.

A Cu—Ni—Si based copper alloy containing Ni and Si: in a center portion in a plate thickness direction, containing 0.4% by mass or more and 5.0% by mass or less of Ni, 0.05% by mass or more and 1.5% by mass or less of Si, and the balance Cu and inevitable impurities; where an Ni concentration on a plate surface is 70% or less of a center Ni concentration in the thickness center portion; a surface layer portion having a depth from the plate surface to be 90% of the center Ni concentration; in the surface layer portion, the Ni concentration increases from the plate surface toward the thickness center portion at 5.0% by mass/.Math.m or more and 100% by mass/.Math.m or less of a concentration gradient; to improve the electric connection reliability under high-temperature environment.

The disclosure provides a Sn—In electroplating bath that is Pb-free, environmentally safe, operates at room temperature, and does not require changes in existing plating assemblies. Room temperature aging and limited thermal cycling tests show that the electroplated Sn—In alloy film on a Cu substrate effectively mitigates whisker growth.

The disclosure provides a Sn—In electroplating bath that is Pb-free, environmentally safe, operates at room temperature, and does not require changes in existing plating assemblies. Room temperature aging and limited thermal cycling tests show that the electroplated Sn—In alloy film on a Cu substrate effectively mitigates whisker growth.