Features of Machine Variables in Thermosonic Flip Chip
An assembly bed on thermosonic flip chip bonding was set up, two different structures of tool tips were designed, and a series of experiments on flip chip and bonding machine variables were carried out. Lift-off characteristics of thermosonic flip chip were investigated by using Scanning Electron Microscope (JSM-6360LV), and vibration features of tool tips driven by high frequency were tested by using PSV-400-M2 Laser Doppler Vibrometer. Results show that, for chip-press model, slippage and rotation phenomena between tool tip and chip have been solved by using tool with greater area tip pattern during flip-chip bonding process, and welding failures appeared in chip-collet model have been controlled. Greater area pattern on tool tip is better than small area pattern. The power of ‘n’ bumps on flip chip bonding is far smaller than that of n×(the power of single wire bonding). The power is directly proportion to vibration displacement driven by the power, high-power decrease positioning precision of flip chip bonding or result in slippage and rotation phenomena. The proper machine variables ranges for thermosonic flip chip had been obtained.
Shen Dong and Yingxue Yao
J. H. Li et al., "Features of Machine Variables in Thermosonic Flip Chip", Key Engineering Materials, Vol. 339, pp. 257-262, 2007