Innovative High Throughput TCB Process
To introduce an innovative high throughput TCB process, Liquid Phase Contact Thermal Compression Bonding (LPC TCB) process, for fine-pitch copper pillar with solder cap flip chip packages. It offers not only high throughput but reliable interconnection. A series of LPC TCB experimental data using both Chip-on-Substrate (CoS) and Chip-on-Chip (CoC) packages will be reviewed.
The LPC TCB bonding profile clearly indicates that a high throughput, UPH (units per hour) of 1.2k, can be achieved compared with UPH of ~600 for a conventional TCB-flux process. With a bond head (BH) cooling step, a precise solder height can be obtained based on a pre-determined bonding level, while without a BH cooling step, the solder height remained at a constant value regardless the bonding level. The restoring force from the surface tension was calculated to explain this phenomenon. Without a cooling step, the UPH can further be increased to close to 2K.