Apparatus for forming a double-bump structure used for flip-chip mounting

A bump structure comprising:

• a first bump made of a conductive material, a first surface of which is fixed to an electrode of a substrate, and which is substantially spherical and has a projected portion at a center portion on a second surface thereof;
• said second surface being on the opposite side of said first bump from said first surface;
• and
• a second bump made of a conductive material, and covering said projected portion on said first bump, but not touching said electrode;
• wherein said second bump has the diameter which is 40%-80% of the diameter of said first bump.

A flip-chip connecting structure comprising:

• a first bump made of a conductive material, a first surface of which is fixed to a first electrode of a first substrate, and which is substantially spherical and has a projected portion at a center portion on a second surface thereof, said second surface being on the opposite side of said first bump from said first surface;
• and
• a second bump made of a conductive material having a diameter less than that of said first bump, and being configured such that it interconnects said second electrode and said first bump but does not touch said first electrode;
• said first bump being made of a metal having properties of preventing said second bump from diffusing and of adhering to said second bump.

A flip-chip connecting structure comprising:

• a first bump made of a conductive material, a first surface of which is fixed to a first electrode of a first substrate, and which is substantially spherical and has a projected portion at a center portion on a second surface thereof, said second surface being on the opposite side of said first bump from said first surface;
• and
• a second bump made of a conductive material, and being configured such that it interconnects said second electrode and said first bump but does not touch said first electrode;
• wherein said second bump has the diameter which is 40%-80% of the diameter of said first bump.