Embodiments of the present disclosure are directed towards techniques and configurations of interconnect structures having a polymer core in integrated circuit (IC) package assemblies. In one embodiment, an apparatus includes a first die having a plurality of transistor devices disposed on an active side of the first die and a plurality of interconnect structures electrically coupled with the first die, wherein individual interconnect structures of the plurality of interconnect structures have a polymer core, and an electrically conductive material disposed on the polymer core, the electrically conductive material being configured to route electrical signals between the transistor devices of the first die and a second die. Other embodiments may be described and/or claimed.

A method is disclosed of fabricating a microelectronic package comprising a substrate overlying the front face of a microelectronic element. A plurality of metal bumps project from conductive elements of the substrate towards the microelectronic element, the metal bumps having first ends extending from the conductive elements, second ends remote from the conductive elements, and lateral surfaces extending between the first and second ends. The metal bumps can be wire bonds having first and second ends attached to a same conductive pad of the substrate. A conductive matrix material contacts at least portions of the lateral surfaces of respective ones of the metal bumps and joins the metal bumps with contacts of the microelectronic element.

A method is disclosed of fabricating a microelectronic package comprising a substrate overlying the front face of a microelectronic element. A plurality of metal bumps project from conductive elements of the substrate towards the microelectronic element, the metal bumps having first ends extending from the conductive elements, second ends remote from the conductive elements, and lateral surfaces extending between the first and second ends. The metal bumps can be wire bonds having first and second ends attached to a same conductive pad of the substrate. A conductive matrix material contacts at least portions of the lateral surfaces of respective ones of the metal bumps and joins the metal bumps with contacts of the microelectronic element.

Methods of fabricating semiconductor packages are provided. One of the methods includes forming a protection layer including metal on a first surface of a substrate to cover a semiconductor device disposed on the first surface of the substrate, attaching a support substrate to the protection layer by using an adhesive member, processing a second surface of the substrate opposite to the protection layer to remove a part of the substrate, and detaching the support substrate from the substrate.

Disclosed technology provides a solder ball including an outer layer having a first conductive material that is solid at an operating temperature of an electronic device, and an inner region having a second conductive material that flows at the operating temperature of the electronic device, wherein the inner region is surrounded by the outer layer. A method of manufacturing a solder ball includes forming an outer layer comprising a first conductive material that is solid at an operating temperature of an electronic device, wherein the outer layer surrounds an inner region, introducing a hole into the outer layer, injecting a second conductive material through the hole of the outer layer into the inner region, wherein the second conductive material flows at the operating temperature of the electronic device, and sealing the hole of the outer layer such that the second conductive material is retained within the inner region.

A microelectronic device has a bump bond structure including an electrically conductive pillar with an expanded head, and solder on the expanded head. The electrically conductive pillar includes a column extending from an I/O pad to the expanded head. The expanded head extends laterally past the column on at least one side of the electrically conductive pillar. In one aspect, the expanded head may have a rounded side profile with a radius approximately equal to a thickness of the expanded head, and a flat top surface. In another aspect, the expanded head may extend past the column by different lateral distances in different lateral directions. In a further aspect, the expanded head may have two connection areas for making electrical connections to two separate nodes. Methods for forming the microelectronic device are disclosed.

A microelectronic device has a bump bond structure including an electrically conductive pillar with an expanded head, and solder on the expanded head. The electrically conductive pillar includes a column extending from an I/O pad to the expanded head. The expanded head extends laterally past the column on at least one side of the electrically conductive pillar. In one aspect, the expanded head may have a rounded side profile with a radius approximately equal to a thickness of the expanded head, and a flat top surface. In another aspect, the expanded head may extend past the column by different lateral distances in different lateral directions. In a further aspect, the expanded head may have two connection areas for making electrical connections to two separate nodes. Methods for forming the microelectronic device are disclosed.

A semiconductor package may include a package substrate including a substrate pad, a solder ball in contact with a bottom surface of the substrate pad, and a core enclosed by the solder ball. An area of a bottom surface of the core may be larger than an area of a top surface of the core.