Room temperature microjoining of qVGA class area-bump array using cone bump

We show that room temperature microjoining a 332 × 268 array of bumps can be realized by using ultrasonic bonding of cone-shaped microbump. 20 µm-pitch area array of cone-shaped Au bump was fabricated on a Si wafer by using a photolithography and electroplating. A flat planar electrode made of electoplated Au was used as the counter electrode. Ultrasonic bonding was carried out at room temperature in ambient air. Electrical connection test shows all bump connections with low resistance have been achieved.