A method for producing a joined structure according to the present invention includes: a reflow step of heating a first member and a solder material while keeping them in contact with each other in a reflow chamber to melt a solder alloy constituting the solder material, the reflow step including: a first reflow step of melting the solder alloy with an atmosphere in the reflow chamber reduced to a first pressure P.sub.1 lower than the atmospheric pressure; and a second reflow step of, after the first reflow step, melting the solder alloy with the atmosphere in the reflow chamber reduced to a second pressure P.sub.2 lower than the first pressure P.sub.1.

A method for producing a joined structure according to the present invention includes: a reflow step of heating a first member and a solder material while keeping them in contact with each other in a reflow chamber to melt a solder alloy constituting the solder material, the reflow step including: a first reflow step of melting the solder alloy with an atmosphere in the reflow chamber reduced to a first pressure P.sub.1 lower than the atmospheric pressure; and a second reflow step of, after the first reflow step, melting the solder alloy with the atmosphere in the reflow chamber reduced to a second pressure P.sub.2 lower than the first pressure P.sub.1.

Improved electrical and thermal properties of solder alloys are achieved by the use of micro-additives in solder alloys to engineer the electrical and thermal properties of the solder alloys and the properties of the reaction layers between the solder and the metal surfaces. The electrical and thermal conductivity of alloys and that of the reaction layers between the solder and the -metal surfaces can be controlled over a wide range of temperatures. The solder alloys produce stable microstructures wherein such stable microstructures of these alloys do not exhibit significant changes when exposed to changes in temperature, compared to traditional interconnect materials.

An electrical interconnect structure includes a bond pad having a substantially planar bonding surface, and a solder enhancing structure that is disposed on the bonding surface and includes a plurality of raised spokes that are each elevated from the bonding surface. Each of the raised spokes has a lower wettability relative to a liquefied solder material than the bonding surface. Each of the raised spokes extend radially outward from a center of the solder enhancing structure.

An electrical interconnect structure includes a bond pad having a substantially planar bonding surface, and a solder enhancing structure that is disposed on the bonding surface and includes a plurality of raised spokes that are each elevated from the bonding surface. Each of the raised spokes has a lower wettability relative to a liquefied solder material than the bonding surface. Each of the raised spokes extend radially outward from a center of the solder enhancing structure.

A method for producing a joined structure according to the present invention includes: a reflow step of heating a first member and a solder material while keeping them in contact with each other in a reflow chamber to melt a solder alloy constituting the solder material, the reflow step including: a first reflow step of melting the solder alloy with an atmosphere in the reflow chamber reduced to a first pressure P.sub.1 lower than the atmospheric pressure; and a second reflow step of, after the first reflow step, melting the solder alloy with the atmosphere in the reflow chamber reduced to a second pressure P.sub.2 lower than the first pressure P.sub.1.

A method for producing a joined structure according to the present invention includes: a reflow step of heating a first member and a solder material while keeping them in contact with each other in a reflow chamber to melt a solder alloy constituting the solder material, the reflow step including: a first reflow step of melting the solder alloy with an atmosphere in the reflow chamber reduced to a first pressure P.sub.1 lower than the atmospheric pressure; and a second reflow step of, after the first reflow step, melting the solder alloy with the atmosphere in the reflow chamber reduced to a second pressure P.sub.2 lower than the first pressure P.sub.1.

Improved electrical and thermal properties of solder alloys are achieved by the use of micro-additives in solder alloys to engineer the electrical and thermal properties of the solder alloys and the properties of the reaction layers between the solder and the metal surfaces. The electrical and thermal conductivity of alloys and that of the reaction layers between the solder and the -metal surfaces can be controlled over a wide range of temperatures. The solder alloys produce stable microstructures wherein such stable microstructures of these alloys do not exhibit significant changes when exposed to changes in temperature, compared to traditional interconnect materials.

Embodiments herein may relate to an apparatus with a package that includes a first substrate soldered to a second substrate via solder comprising an off-eutectic solder material. The off-eutectic solder material may form a joint between the first substrate and the second substrate. The off-eutectic solder material may be any suitable material that melts over a range of temperatures, which may provide a relatively slow collapse of the off-eutectic solder material during a melting process. The relatively slow collapse may provide a sufficient amount of time for gases to escape prior to collapse, and thus, the joint between the first substrate and the second substrate may have less voids compared to joints formed using eutectic solder materials. Other embodiments may be described and/or claimed.

Embodiments herein may relate to an apparatus with a package that includes a first substrate soldered to a second substrate via solder comprising an off-eutectic solder material. The off-eutectic solder material may form a joint between the first substrate and the second substrate. The off-eutectic solder material may be any suitable material that melts over a range of temperatures, which may provide a relatively slow collapse of the off-eutectic solder material during a melting process. The relatively slow collapse may provide a sufficient amount of time for gases to escape prior to collapse, and thus, the joint between the first substrate and the second substrate may have less voids compared to joints formed using eutectic solder materials. Other embodiments may be described and/or claimed.