Ag-In transient liquid phase bonding for high temperature stainless steel micro actuators

Sammanfattning: A stainless steel, high temperature, phase change micro actuator has been demonstrated using the solid-liquid phase transition of mannitol at 168°C and In-Ag transient liquid phase diffusion bonding. Joints created with this bonding technique can sustain temperatures up to 695°C, while being bonded at only 180°C, and have thicknesses between 1.4 to 6.0 μm. Physical vapour deposition, inkjet printing and electroplating have been evaluated as deposition methods for bond layers. For actuation, cavities were filled with mannitol and when heated, the expansion was used to deflect a 10 μm thick stainless steel membrane. Bond strengths of the joints are found to be in the region of 0.51 to 2.53 MPa and pressurised cavities sustained pressures of up to 30 bar. Bond strength is limited by the bond contact area and the surface roughness of the bonding layers.