Active Control of NCF Fillet Shape for 3D CoW by Multi Beam Laser Bonder

Non-conductive film fillet control during the thermal compression bonding using a multi laser beam bonder was investigated comparing with the case of using a conventional ceramic pulse heater bonder. The laser bonder can control each laser beam power individually, which can change the temperature distribution in the heated die. Fillet coverage index was defined as the ratio of the fillet width of the die corner and the maximum point of the die peripheral. The optimization of the temperature distribution of the die by the laser bonder could enlarge FCI from 0.25 with even reducing the fillet width at the maximum point of the die peripheral from 167 μm in comparison to those of 0.33 and 187 μm, which were obtained using a conventional bonder with a ceramics pulse heater, respectively.