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.

Provided is a solder material having oxidation resistance at the time of melting solder or after melting it, as well as managing a thickness of oxide film at a fixed value or less before melting the solder. A Cu core ball 1A is provided with a Cu ball 2A for keeping a space between a semiconductor package and a printed circuit board and a solder layer 3A that covers the Cu ball 2A. The solder layer 3A is composed of Sn or a solder alloy whose main component is Sn. For the Cu core ball 1A, lightness is equal to or more than 65 in the L*a*b* color space and yellowness is equal to or less than 7.0 in the L*a*b* color space, and more preferably, the lightness is equal to or more than 70 and the yellowness thereof is equal to or less than 5.1.

Provided is a solder material having oxidation resistance at the time of melting solder or after melting it, as well as managing a thickness of oxide film at a fixed value or less before melting the solder. A Cu core ball 1A is provided with a Cu ball 2A for keeping a space between a semiconductor package and a printed circuit board and a solder layer 3A that covers the Cu ball 2A. The solder layer 3A is composed of Sn or a solder alloy whose main component is Sn. For the Cu core ball 1A, lightness is equal to or more than 65 in the L*a*b* color space and yellowness is equal to or less than 7.0 in the L*a*b* color space, and more preferably, the lightness is equal to or more than 70 and the yellowness thereof is equal to or less than 5.1.

The surface of a substrate made of stainless steel foil is coated with a Sn alloy layer, with a strike layer in between. The coating weight of the strike layer is 0.001 g/m.sup.2 to 1 g/m.sup.2.

Functionalized microscale 3D devices and methods of making the same. The 3D microdevice can be realized with the combination of top-down (lithographic) and bottom-up (origami-inspired self-assembly) processes. The origami-inspired self-assembly approach combined with a top-down process can realize 3D microscale polyhedral structures with metal/semiconductor materials patterned on dielectric materials. In some embodiments, the functionalized 3D microdevices include resonator-based passive sensors, i.e. split ring resonators (SRRs), on 3D, transparent, free-standing, dielectric media (Al.sub.2O.sub.3).

Reaction products of halogenated pyrimidines and nucleophilic linker units are included in metal electroplating baths to provide good throwing power. The electroplating baths can be used to plate metal, such as copper, tin and alloys thereof on printed circuit boards and semiconductors and fill through-holes and vias.

Reaction products of halogenated pyrimidines and nucleophilic linker units are included in metal electroplating baths to provide good throwing power. The electroplating baths can be used to plate metal, such as copper, tin and alloys thereof on printed circuit boards and semiconductors and fill through-holes and vias.

A solder-coated ball (10A) includes a spherical core containing Ni and P; and a solder layer (12) formed to coat the core (11). A solder-coated ball (10B) further includes a Cu plating layer (13) formed between the core (11) and the solder layer (12). A solder-coated ball (10C) further includes an Ni plating layer (14) formed between the Cu plating layer (13) and the solder layer (12).

A solder-coated ball (10A) includes a spherical core containing Ni and P; and a solder layer (12) formed to coat the core (11). A solder-coated ball (10B) further includes a Cu plating layer (13) formed between the core (11) and the solder layer (12). A solder-coated ball (10C) further includes an Ni plating layer (14) formed between the Cu plating layer (13) and the solder layer (12).