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.

Provided is a composition for conductive adhesive. The composition for conductive adhesive includes a heterocyclic compound containing oxygen and including at least one of an epoxy group or oxetane group, a reductive curing agent including an amine group and a carboxyl group, and a photoinitiator, wherein a mixture ratio of the heterocyclic compound and the reductive curing agent satisfies Conditional Expression 1 below.

0.5≤(b+c)/a≤1.5, a>0, b≥0, c>0  [Conditional Expression 1] where ‘a’ denotes a mole number of a heterocycle in the heterocyclic compound, ‘b’ denotes a mole number of hydrogen bonded to a nitrogen atom of the amine group included in the reductive curing agent, and ‘c’ denotes a mole number of the carboxyl group.

Provided is a composition for conductive adhesive. The composition for conductive adhesive includes a heterocyclic compound containing oxygen and including at least one of an epoxy group or oxetane group, a reductive curing agent including an amine group and a carboxyl group, and a photoinitiator, wherein a mixture ratio of the heterocyclic compound and the reductive curing agent satisfies Conditional Expression 1 below.

0.5≤(b+c)/a≤1.5, a>0, b≥0, c>0  [Conditional Expression 1] where ‘a’ denotes a mole number of a heterocycle in the heterocyclic compound, ‘b’ denotes a mole number of hydrogen bonded to a nitrogen atom of the amine group included in the reductive curing agent, and ‘c’ denotes a mole number of the carboxyl group.

An electroplating method that is a conventional method has had a problem that it is difficult to manufacture fine pillars without being affected by an undercut. Furthermore, an electroless plating method has had a problem that it is difficult to manufacture pillars having the same shape without any void. The inventors have performed intensive investigations to solve the above problems and, as a result, have found that fine conductive pillars with a high aspect ratio can be readily manufactured on a substrate having an electrode section in such a manner that after a conductive paste containing metal micro-particles is applied in a reduced pressure state, the conductive paste is exposed to standard pressure. The present invention has a particular effect on the manufacture of a metal pillar that is a terminal for flip-chip mounting.

An electroplating method that is a conventional method has had a problem that it is difficult to manufacture fine pillars without being affected by an undercut. Furthermore, an electroless plating method has had a problem that it is difficult to manufacture pillars having the same shape without any void. The inventors have performed intensive investigations to solve the above problems and, as a result, have found that fine conductive pillars with a high aspect ratio can be readily manufactured on a substrate having an electrode section in such a manner that after a conductive paste containing metal micro-particles is applied in a reduced pressure state, the conductive paste is exposed to standard pressure. The present invention has a particular effect on the manufacture of a metal pillar that is a terminal for flip-chip mounting.

The known electrolytic plating method is disadvantageous in that it is difficult to form thin pillars without being influenced by undercuts. The electroless plating method is disadvantageous in that it is difficult to form pillars in the same shape without voids. As a solution to these, the electrically conductive paste according to the present invention for forming pillars is used to make pillars by filling. This helps prevent undercuts, and it is also intended to provide metal pillars in the same shape with good reproducibility. The inventors found that an electrically conductive paste that is very small fine metal particles and contains a particular percentage of fine metal particles is extraordinarily advantageous in forming pillars.

The known electrolytic plating method is disadvantageous in that it is difficult to form thin pillars without being influenced by undercuts. The electroless plating method is disadvantageous in that it is difficult to form pillars in the same shape without voids. As a solution to these, the electrically conductive paste according to the present invention for forming pillars is used to make pillars by filling. This helps prevent undercuts, and it is also intended to provide metal pillars in the same shape with good reproducibility. The inventors found that an electrically conductive paste that is very small fine metal particles and contains a particular percentage of fine metal particles is extraordinarily advantageous in forming pillars.

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.