Batch transfer of LIGA microstructures by selective electroplating and bonding

A flip-chip batch transfer process for LIthographie, Galvanoformung and Abformung (LIGA) microstructures has been demonstrated by selective electroplating and bonding. Single layer LIGA microstructures with thickness of 200 μm are fabricated on a dummy substrate first. They are then batch transferred to an IC substrate by means of bonding via electroplating. After the selective bonding process, the originally fixed microstructures become free-standing, moveable devices. The electroplating and bonding process is conducted at 50°C with applied electroplating current density at 68.3 AM² and it takes about 80 minutes to complete the bonding process. Experimentally, an electrothermally-driven LIGA microgripper has been demonstrated to operate after the batch transfer process. When a maximum input current of 1.6 amp is applied, the tip of the microgripper moves 92 μm. This flip-chip assembly process enables a new class of integrated electro-mechanical manufacturing at a low processing temperature massively and in parallel