| 摘要 |
PURPOSE:To enhance the yield of bonding, by plating tin on a copper leaf pattern on a circuit board and laminating a thin gold film on the plated tin to provide a finger and applying heat and pressure to the finger on the gold bump of an IC to connect the finger to the gold bump. CONSTITUTION:Sn 5 and Au 6 are laminated by plating on a copper leaf pattern 2 on a board 1 and then put on the Au bump of an electrode of an IC3. Pressure of 60g per piece is applied to the plated films and the Au bump at about 480 deg.C for about 0.8 second so that the Sn film 5 of a finger 4a is diffused into the Au bump 7 through the Au film 6. As a result, eutectic Au-Sn alloy is produced and the finger and the IC are firmly bonded to each other. The optimal thickness of the Au film 6 is 0.4-0.6mum. According to this constitution, no complicated equipment and method for partial plating or the like are needed and a process advantage is given. Since the Sn film of the finger is protected by the Au film, bonding conditions are stabilized and the yield of mounting is improved. |
