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Proceedings Paper

Modification of an ophthalmic laser for micro-joining on MEMS
Author(s): A. Bruce Wedding; Hung-Yao Hsu; Krishnan Sathyan; Fabien Dauzau
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Paper Abstract

The requirement to make low profile ohmic contacts to a piezo-resistive MEMS pressure sensor has highlighted limitations of ultrasonic wire bonding technology. Wire bonding typically uses 25-50 μm diameter gold or aluminium wire and ultrasonic welding to the contact pads of micro-electronic devices results in a contact wire proud of the pad surface. If the application involves the MEMS pressure sensor and contacts being encapsulated, then repetitive changes in pressure flexing the contact wires can lead to fracture. A possible solution is to scale down laser welding technology to fuse materials at the micron scale. For this purpose a precision ophthalmic surgical laser system has been modified to investigate optimum conditions for laser welding, both at the micron scale and for the typical geometries involved. Typical requirements involve a cylindrical contact wire to be bonded to a thin contact pad on the MEMS device. Since the pad size is of similar dimension to the wire, and the requirement for a low profile stable configuration, a keyhole welding strategy is required. The Nd:YAG based ophthalmic laser has been modified, the Q-switch removed and the output pulse width and energy controlled principally via control of the flashlamp.

Paper Details

Date Published: 23 February 2008
PDF: 8 pages
Proc. SPIE 6880, Laser-based Micro- and Nanopackaging and Assembly II, 68800I (23 February 2008); doi: 10.1117/12.762561
Show Author Affiliations
A. Bruce Wedding, Univ. of South Australia (Australia)
Hung-Yao Hsu, Univ. of South Australia (Australia)
Krishnan Sathyan, Univ. of South Australia (Australia)
Fabien Dauzau, Univ. of South Australia (Australia)

Published in SPIE Proceedings Vol. 6880:
Laser-based Micro- and Nanopackaging and Assembly II
Wilhelm Pfleging; Yongfeng Lu; Kunihiko Washio; Willem Hoving; Jun Amako, Editor(s)

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