SOLEIL uses X-rays produced by the synchrotron ray to manufacture high-precision objects on a micrometric scale using the LIGA procedure (a German acronym for Lithografie/Galvanoformung/Abformung meaning Lithography/Electro-growth/Casting).
This procedure includes 5 main stages:
- Definition of the product researched and manufacturing of corresponding work masks
- X-ray irradiation: impression of resin not hidden by the mask (formation of a latent image)
- Development: revelation of the latent image in resin by means of chemical seizure (solvent)
- Electroforming: deposit of metal to obtain a metallic structure that is a negative replica of the resin, then elimination of the latter
- Casting: use of the metallic structure as a mold for the manufacturing of a series of micro-objects made of various materials (metals, alloys, plastics, or ceramics)
The combination of very high intensity and parallelism (very weak divergence) of the hard X-ray beams (energy included between 2 and 8 keV) from the synchrotron ray permits the obtaining via impression of thick resin casts of micrometric structures with abrupt, smooth vertical inner walls.
LIGA offers, in comparison with other micro-fabrication procedures, the following competitive benefits:
- Obtaining of complex forms and any section, with access to 3 dimensions in a single stage under certain conditions
- Very high shape factor (50 for a “post” type 5µm in diameter and 250µm in height, even greater than 50)
- Increased resistance and excellent surface state (Ra = 30nm)
- Use of various materials (metals, alloys, plastics, or ceramics)
- Parallel manufacturing of various parts (several hundred), identical or not (batch processing) for production in series
