LIGA

LIGA Overview and Technologies:
– LIGA consists of lithography, electroplating, and molding steps.
– Two main LIGA-fabrication technologies are X-Ray LIGA and UV LIGA.
– X-Ray LIGA offers high aspect ratios and precise details, enabling on-demand manufacturing of high-aspect-ratio structures with lateral precision.
– UV LIGA is cheaper and more accessible but less effective at producing precision molds.

X-Ray LIGA vs. UV LIGA:
– X-Ray LIGA was developed in the 1980s by a team at the Karlsruhe Institute of Technology, utilizing X-ray sensitive polymer photoresist.
– Practitioners of X-Ray LIGA are often located close to synchrotron facilities and can fabricate structures in metals, plastics, and ceramics.
– UV LIGA uses an inexpensive ultraviolet light source and a simple chromium mask, making it cheaper and more accessible but less effective at producing precision molds.

LIGA Mask and Development:
– X-ray masks consist of carrier, absorber, and alignment ring components.
– Masks can be fabricated using electron beam lithography, plated photomask, or direct photomask methods.
– Resist-developer system for high-aspect-ratio structures requires specific dissolution rates ratio.
– Future trends for masks include larger formats and smaller feature sizes.

Electroplating and Stripping Process:
– Electroplating involves nickel, copper, or gold plated upward from metalized substrate into voids left by removed photoresist.
– Challenges in plating into PMMA molds can be overcome through empirical optimization of plating chemistry and environment.
– Stripping methods include flood exposure with developing solution or using chemical solvents, followed by backfilling with a polymer-based encapsulant.

LIGA Commercialization and Replication:
– LIGA technology was cutting-edge in the 1990s for MEMS fabrication, with companies like HTmicro and microworks continuing work in LIGA.
– UV LIGA is employed more broadly due to lower production costs, with companies like Veco, Tecan, Temicon, and Mimotec supplying metal parts to the Swiss watch market.
– Replicated components maintain the high precision and quality of the original LIGA-fabricated structures, enabling mass replication through stamping or injection molding.

LIGA (Wikipedia)

This article is about a lithographic fabrication technology. For other uses, see liga (disambiguation).

LIGA is a fabrication technology used to create high-aspect-ratio microstructures. The term is a German acronym for Lithographie, Galvanoformung, Abformung – lithography, electroplating, and molding.