Patent ID: 8211745

Claim:
A method for bonding a flip chip, comprising: forming solder bumps on first electrodes and/or second electrodes disposed on first and second substrates, respectively; arranging the first and second electrodes to face each other with an underfill layer being disposed between the first and second substrates, the underfill layer including spacer balls and a second resin surrounding the spacer balls; and while flowing the second resin, pressing the first and second substrates until distance between the first and second substrates is decreased smaller than diameter of the spacer balls, so as to connect the solder bumps between the first and second electrodes, wherein each spacer ball comprises an elastic material, and, as the distance between the first and second substrate is decreased during the pressing step, each spacer ball deforms to reduce a height of each spacer ball in a thickness direction of the first and second substrates, and a space between the first and second substrates is filled with the underfill layer.