A microelectronic device has a pillar connected to an external terminal by an intermetallic joint. Either the pillar or the external terminal, or both, include copper in direct contact with the intermetallic joint. The intermetallic joint includes at least 90 weight percent of at least one copper-tin intermetallic compound. The intermetallic joint is free of voids having a combined volume greater than 10 percent of a volume of the intermetallic joint; and free of a void having a volume greater than 5 percent of the volume of the intermetallic joint. The microelectronic device may be formed using solder which includes at least 93 weight percent tin, 0.5 weight percent to 5.0 weight percent silver, and 0.4 weight percent to 1.0 weight percent copper, to form a solder joint between the pillar and the external terminal, followed by thermal aging to convert the solder joint to the intermetallic joint.

A microelectronic device has a pillar connected to an external terminal by an intermetallic joint. Either the pillar or the external terminal, or both, include copper in direct contact with the intermetallic joint. The intermetallic joint includes at least 90 weight percent of at least one copper-tin intermetallic compound. The intermetallic joint is free of voids having a combined volume greater than 10 percent of a volume of the intermetallic joint; and free of a void having a volume greater than 5 percent of the volume of the intermetallic joint. The microelectronic device may be formed using solder which includes at least 93 weight percent tin, 0.5 weight percent to 5.0 weight percent silver, and 0.4 weight percent to 1.0 weight percent copper, to form a solder joint between the pillar and the external terminal, followed by thermal aging to convert the solder joint to the intermetallic joint.

An electronic assembly, and a method for making the electronic assembly, includes a first electronic component, a second electronic component, and a plurality of interconnects. The plurality of interconnects electrically couple the first electronic component to the second electronic component. Each of the plurality of interconnects comprise one of a plurality of first magnetic components in physical alignment with an associated one of a plurality of second magnetic components, the plurality of second magnetic components being components of one of the second electronic component and the plurality of interconnects.

A core material has a core; a solder layer provided outside the core and being a solder alloy containing Sn and at least any one element of Ag, Cu, Sb, Ni, Co, Ge, Ga, Fe, Al, In, Cd, Zn, Pb, Au, P, S, Si, Ti, Mg, Pd, and Pt; and a Sn layer provided outside the solder layer. The solder layer has a thickness of 1 μm or more on one side. The Sn layer has a thickness of 0.1 μm or more on one side. A thickness of the Sn layer is 0.215% or more and 36% or less of the thickness of the solder layer.

A semiconductor package may include a base, a first chip on the base, and first connection patterns that connect and couple the base and the first chip. The first chip may include a substrate, pad patterns on the substrate, a passivation layer on the substrate and having openings, and pillars on the substrate, the pad patterns include a first signal pad and a second signal pad, the first connection patterns are in contact with the pillars, the pillars include a first signal pillar in contact with the first signal pad and a second signal pillar in contact with the second signal pad, the openings in the passivation layer include a first opening having a sidewall facing a side surface of the first signal pillar and surrounding the side surface of the first signal pillar, and a second opening having a sidewall facing a side surface of the second signal pillar and surrounding the side surface of the second signal pillar, and a maximum width of the second opening is greater than a maximum width of the first opening.

An electronic assembly, and a method for making the electronic assembly, includes a first electronic component, a second electronic component, and a plurality of interconnects. The plurality of interconnects electrically couple the first electronic component to the second electronic component. Each of the plurality of interconnects comprise one of a plurality of first magnetic components in physical alignment with an associated one of a plurality of second magnetic components, the plurality of second magnetic components being components of one of the second electronic component and the plurality of interconnects.

The present invention accurately distinguishes a soldering material less likely to oxidize. A Cu core ball has a Cu ball having a predetermined size, and a solder layer coating the Cu ball. The Cu ball provides a space between a semiconductor package and a printed circuit board. The Cu core ball has the soldering material having lightness greater than or equal to 62.5 in L*a*b* color space subsequent to a heating storage test performed for 72 hours in a temperature-controlled bath at 150 C. with a temperature of 25 C. and 40% humidity, and the soldering material, prior to the heating storage test, having lightness greater than or equal to 65 in the L*a*b* color space and yellowness less than or equal to 7.0 in the L*a*b* color space.

A microelectronic device has a pillar connected to an external terminal by an intermetallic joint. Either the pillar or the external terminal, or both, include copper in direct contact with the intermetallic joint. The intermetallic joint includes at least 90 weight percent of at least one copper-tin intermetallic compound. The intermetallic joint is free of voids having a combined volume greater than 10 percent of a volume of the intermetallic joint; and free of a void having a volume greater than 5 percent of the volume of the intermetallic joint. The microelectronic device may be formed using solder which includes at least 93 weight percent tin, 0.5 weight percent to 5.0 weight percent silver, and 0.4 weight percent to 1.0 weight percent copper, to form a solder joint between the pillar and the external terminal, followed by thermal aging to convert the solder joint to the intermetallic joint.

A microelectronic device has a pillar connected to an external terminal by an intermetallic joint. Either the pillar or the external terminal, or both, include copper in direct contact with the intermetallic joint. The intermetallic joint includes at least 90 weight percent of at least one copper-tin intermetallic compound. The intermetallic joint is free of voids having a combined volume greater than 10 percent of a volume of the intermetallic joint; and free of a void having a volume greater than 5 percent of the volume of the intermetallic joint. The microelectronic device may be formed using solder which includes at least 93 weight percent tin, 0.5 weight percent to 5.0 weight percent silver, and 0.4 weight percent to 1.0 weight percent copper, to form a solder joint between the pillar and the external terminal, followed by thermal aging to convert the solder joint to the intermetallic joint.

A method includes aligning a first electrical connector of a first package component to a second electrical connector of a second package component. With the first electrical connector aligned to the second electrical connector, a metal layer is plated on the first and the second electrical connectors. The metal layer bonds the first electrical connector to the second electrical connector.