Patent ID: 7100279

Claim:
A method, of mounting an electronic part on a board, in which an electronic part and a mounting board on which the electronic part is to be mounted are placed in a vacuum or inert atmosphere, and the electronic part is mounted on the board by bringing bonding members of the electronic part and the board into contact with each other at normal-temperature substantially below a melting point of a material from which the bonding members are made, to thereby mount the electronic part on the board, the method comprising: forming the bonding members of at least one of the electronic part and the board out of a solder material, in a form of a bump placing the electronic part and the board in the vacuum or the inert atmosphere; activating a surface of the bonding members so as to remove oxides from the surface; bringing the bonding members of the electronic part and the board into contact with each other without preprocessing the bonding surfaces of the bonding members; wherein said preprocessing comprises a process for planarization selected from the group consisting of: CPM, and electropolishing against variations in a roughness or a height of bonding surfaces; wherein said solder material is deformed during said bonding to absorb the variations in the roughness or the height of the bonding surfaces to be in close contact with the bonding surface; and wherein said solder material is a solder material that needs a vertical load of not greater than 100 grams to change the height of a spherical bump, having a diameter in a direction parallel to an electronic Part body of 130 μm by 8 μm.