A system of producing metal cored solder structures on a substrate includes: a decal having a plurality of apertures, the apertures being tapered from a top surface to a bottom surface of the decal; a carrier configured for positioning beneath the bottom of the decal, the carrier having cavities in a top surface and the cavities located in alignment with the apertures of the decal; the decal being configured for positioning on the carrier having the decal bottom surface in contact with the carrier top surface to form feature cavities defined by the decal apertures and the carrier cavities, the feature cavities being shaped to receive a plurality of metal elements therein, the feature cavities configured for receiving molten solder being cooled in the cavities, the decal being separable from the carrier to partially expose metal core solder contacts; and receiving elements of a substrate being configured to receive the metal core solder contacts thereon, and the metal core solder contacts being exposed and positioned on the substrate.

An embodiment bump on trace (BOT) structure includes a contact element supported by an integrated circuit, an under bump metallurgy (UBM) feature electrically coupled to the contact element, a metal bump on the under bump metallurgy feature, and a substrate trace on a substrate, the substrate trace coupled to the metal bump through a solder joint and intermetallic compounds, a ratio of a first cross sectional area of the intermetallic compounds to a second cross sectional area of the solder joint greater than forty percent.

A bump structure includes a contact element formed on a substrate and a passivation layer overlying the substrate. The passivation layer includes a passivation opening exposing the contact element. The bump structure also includes a polyimide layer overlying the passivation layer and an under bump metallurgy (UBM) feature electrically coupled to the contact element. The polyimide layer has a polyimide opening exposing the contact element, and the under bump metallurgy feature has a UBM width. The bump structure further includes a copper pillar on the under bump metallurgy feature. A distal end of the copper pillar has a pillar width, and the UBM width is greater than the pillar width.

An electronic package includes a pad, a dielectric layer, a bump, and a conductive element. The dielectric layer encapsulates the pad and includes an opening exposing the pad. The bump is disposed over the pad. The conductive element is disposed in the opening between the pad and the bump. The conductive element is configured to mitigate a shrinkage of an electrical path between the pad and the bump occupied by an expansion of the dielectric layer.

A semiconductor device includes a first carrier including a first pad, a second carrier including a second pad disposed opposite to the first pad, a joint coupled with and standing on the first pad, a joint encapsulating the post and bonding the first pad with the second pad, a first entire contact interface between the first pad and the joint, a second entire contact interface between the first pad and the post, and a third entire contact interface between the joint and the second pad. The first entire contact interface, the second entire contact interface and the third entire contact interface are flat surfaces. A distance between the first entire contact interface and the third entire contact interface is equal to a distance between the second entire contact interface and the third entire contact interface. The second entire contact interface is a continuous surface.

External electrical connectors and methods of forming such external electrical connectors are discussed. A method includes forming an external electrical connector structure on a substrate. The forming the external electrical connector structure includes plating a pillar on the substrate at a first agitation level affected at the substrate in a first solution. The method further includes plating solder on the external electrical connector structure at a second agitation level affected at the substrate in a second solution. The second agitation level affected at the substrate is greater than the first agitation level affected at the substrate. The plating the solder further forms a shell on a sidewall of the external electrical connector structure.

External electrical connectors and methods of forming such external electrical connectors are discussed. A method includes forming an external electrical connector structure on a substrate. The forming the external electrical connector structure includes plating a pillar on the substrate at a first agitation level affected at the substrate in a first solution. The method further includes plating solder on the external electrical connector structure at a second agitation level affected at the substrate in a second solution. The second agitation level affected at the substrate is greater than the first agitation level affected at the substrate. The plating the solder further forms a shell on a sidewall of the external electrical connector structure.

An embodiment bump on trace (BOT) structure includes a contact element supported by an integrated circuit, an under bump metallurgy (UBM) feature electrically coupled to the contact element, a metal ladder bump mounted on the under bump metallurgy feature, the metal ladder bump having a first tapering profile, and a substrate trace mounted on a substrate, the substrate trace having a second tapering profile and coupled to the metal ladder bump through direct metal-to-metal bonding. An embodiment chip-to-chip structure may be fabricated in a similar fashion.

A bump structure includes a contact element formed on a substrate and a passivation layer overlying the substrate. The passivation layer includes a passivation opening exposing the contact element. The bump structure also includes a polyimide layer overlying the passivation layer and an under bump metallurgy (UBM) feature electrically coupled to the contact element. The polyimide layer has a polyimide opening exposing the contact element, and the under bump metallurgy feature has a UBM width. The bump structure further includes a copper pillar on the under bump metallurgy feature. A distal end of the copper pillar has a pillar width, and the UBM width is greater than the pillar width.

A semiconductor device includes a semiconductor substrate, a pad electrode formed on the semiconductor substrate, a post electrode formed on the pad electrode and made of a copper film, a solder ball electrode formed on the post electrode and made of ternary alloy containing tin, a terminal connected to the solder ball electrode and formed on a front surface of a wiring board, and a sealing material filling a gap between the semiconductor substrate and the wiring board. The post electrode includes a cylindrical stem portion and an overhanging portion positioned in an upper part of the stem portion and protruding to an outer side of the stem portion, the solder ball electrode is connected to an upper surface of the post electrode over the stem portion and the overhanging portion, and a sidewall of the stem portion contacts with the sealing material over the entire circumference thereof.