Vertical and Horizontal Parallel Mounting of Micro Components on a Substrate with High Surface Coverage

We demonstrate a novel parallel micro assembly process based on both shape recognition and capillary-driven self-assembly in an air environment. Mechanically diced silicon parts with dimensions of 790 µ m × 790 µ m × 330 µ m are used for proof-of-concept demonstrations. Each part has only one hydrophobic 790 µ m × 790 µ m face and its other faces are hydrophilic. On a vibrating plate, tumbling parts are captured by cavities having an opening clearance that only admits a single part standing vertically with a 790 µ m × 330 µ m footprint. The trapped parts are then transferred to a substrate having an array of receptor sites covered with water droplets. Initially the parts are vertically attached, but capillary forces from water condensate turn them to face the substrate with their 790 µ m × 790 µ m hydrophilic faces. This process assembles micro parts to densely packed 1000 receptor sites in about 2 minutes with a defect rate ~ 1%. A single batch assembly process achieves 31% surface coverage, and a 2 nd batch doubles the ratio to 62%.