Batch Transfer Apparatus For Chips Resulting In Enlarged Pitch Using Stretchable Silicon Spring

This study presents an expansion apparatus for batch transfer of chips using silicon strips connected by stretchable springs, as shown in Fig. 1. The array of device chips is placed in the pockets of strips, which are mechanically connected by stretchable springs. The pitches of chips are changed as the strips are expanded on 1-D direction. Merits of this approach include: (1) narrow silicon springs (3.5 mu m) can be easily fabricated to minimize strain (<1%) induced by deformation; (2) high aspect ratio springs (9: 1) can be fabricated to provide robustness for springs stretching and recovering; (3) large spring expansion (>4 times) can be achieved. In applications, accurate positioning (similar to 7 mu m) of the expanded strips and durability of the apparatus for >10000 operation cycles are implemented and demonstrated.