LIGA stands for Lithographie Galvanoformung Abformung (Lithographic electroforming Molding). The process was developed at Karlsruhe Laboratory in Germany. Using this process, it is possible to expose a resist with a thickness of 100um depending on the wavelength of the UV beam used.
The UV radiation is used to expose a resist structure through an UV mask. This resin resist structure is developed and etched away (negative). The Ni-Mn and Ni-W alloy is electroformed to create a positive cast. This cast is polished to a desired thickness. The resin is then ashed, leaving the Ni-Mn and Ni-W cast of desired thickness. This cast is used to create a mold resin. This mold is cured and used to separate the Ni-Mn and Ni-W cast from the Titanium substrate. The mold resin is then ashed to leave the finished parts.
The drawbacks to this process include the 2.5 dimensional constraint, but the benefits of highly accurate complex formations must be recognized as required in the market of high density contact pin probes.
For transducer applications, this process allows tighter control and uniformity for rod dimensions, and high aspect ratio compared to conventional "dice and fill" method of construction.