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Proceedings Paper

Laser-LIGA for Serpentine Ni Microstructure
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Paper Abstract

A pulsed excimer laser (248 nm) based LIGA-like process is presented for the fabrication of Ni serpentine microstructures, such as those that might be used for micro-heaters. The structures were produced on both Cu (60 micrometers ) clad PCB and on Cu/Ti (up to 4 micrometers /15 nm) sputtered Si (100) substrates. The substrates were coated with a Laminar dry film (35 micrometers ) photoresist, which was then patterned by laser ablation to produce the mould for Ni electroforming. The optimal ablation conditions were identified for laser patterning to prepare the micro polymer mould. Beam fluence (~ 1 J/cm2) and number of shots (~ 60 pulses) for 50 micrometers wide features on this photoresist were established, and it was observed that an increased number of shots and increased fluence were needed for features less than 20 micrometers wide. Additionally, the Cu layer surface was cleaned by the use of 5 -10 laser pulses at the same fluence. Ni electroforming has been carried out using standard Ni sulfamate bath at a current density of ~ 10 mA/cm2. After Ni electroforming, both the Laminar dry film and the Cu layers around the electroformed Ni patterns were removed using a combination of acetone, laser and Cu selective etching. Finally, a series of Ni microstructures were fabricated consisting of up to 50 micrometers wide and 35 micrometers thick serpentine tracks. The devices were measured using a scanning confocal microscope and it was found that using the excimer laser to remove the remaining dry film laminate also smoothed the electroplated Ni surfaces from a pre-laser treated Ra of 1.20 micrometers to 0.19 micrometers . Laser ablation also released the finer features from the substrate.

Paper Details

Date Published: 21 November 2001
PDF: 6 pages
Proc. SPIE 4592, Device and Process Technologies for MEMS and Microelectronics II, (21 November 2001); doi: 10.1117/12.448962
Show Author Affiliations
Hengyi Jin, Swinburne Univ. of Technology (Australia)
Erol C. Harvey, Swinburne Univ. of Technology (Australia)
Jason P. Hayes, Swinburne Univ. of Technology (Australia)
Muralihar K. Ghantasala, Swinburne Univ. of Technology (Australia)
Andrew John Dowling, Swinburne Univ. of Technology (Australia)
Matthew Solomon, Swinburne Univ. of Technology (Australia)
Sam T. Davies, Univ. of Warwick (United Kingdom)

Published in SPIE Proceedings Vol. 4592:
Device and Process Technologies for MEMS and Microelectronics II
Jung-Chih Chiao; Lorenzo Faraone; H. Barry Harrison; Andrei M. Shkel, Editor(s)

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