AML, the manufacturer of the LCN's Anodic Bonder, is celebrating 25 years and as part of the celebrations they have put a video together which can be viewed on You Tube.
Anodic bonding is a method of hermetically and permanently joining glass to silicon without the use of adhesives. The silicon and glass wafers are heated to a temperature at which the alkali-metal ions in the glass become mobile. The components are brought into contact and a high voltage applied across them. This causes the alkali cations to migrate from the interface resulting in a depletion layer with high electric field strength. The resulting electrostatic attraction brings the silicon and glass into intimate contact. Further current flow of the oxygen anions from the glass to the silicon results in an anodic reaction at the interface and the result is that the glass becomes bonded to the silicon with a permanent chemical bond.
The technique of anodic bonding has found many applications in the field of MST, MEMS or microengineering. These include the fabrication of pressure sensors, accelerometers, micropumps and other fluid handling devices. The process is also used for first order packaging of silicon microstuctures to isolate package induced stresses. By having the sensitive microstructure bonded to a relatively thick (~1mm) glass base the device can be mounted on PCB's and other substrates having a thermal expansion mismatch with silicon. In this manner, the high stress regions, which would have occurred in the silicon microstructure, instead occur in the glass.
The LCN's Anodic Bonder is in Cleanroom Tunnel 1 at the Bloomsbury site. For more information, and to book this piece of equipment, see: