Fabrication of LIGA mold inserts

Abstract

The present paper describes the fabrication sequence of a LIGA mold insert by electroforming after the patterning steps of the overall process. These tools are applied for large scale fabrication of microcomponents made by molding and embossing processes. The application of an intermediate layer system leads to optimized process performance and to a better surface quality of the mold insert. The plating processes are described and the materials properties, e.g. hardness, are used for the characterization of the recrystallization behavior of the electroformed nickel which yields the high temperature application limit of the tool.

Thermal stability of electrodeposited LIGA Ni–W alloys for high temperature MEMS applications

“…The microhardness values of pure nickel drop strongly after annealing and reach a plateau at the value of *100 HV which represents only 33% of the initial value (before annealing) as shown in (Bacher 1998).…”

Numerical simulation and fabrication of microscale, multilevel, tapered mold inserts using UV-Lithographie, Galvanoformung, Abformung (LIGA) technology

“…After etching of the Cr/Au seed layer, the Ni insert together with the SU-8 plating mold was dipped into a Dynasolve solution at $90°C, the SU-8 plating mold was removed in $30 min. According to Bacher et al (1998), the hardness of electrodeposited Ni shows no obvious change when the annealing temperature is below 200°C. Significant softening of the electrodeposited Ni insert is therefore not expected due to the SU-8 removal process.…”

Polymer materials for microsystem technologies

“…Thus, attacks by the developer can be avoided in unlighted areas. By subsequent electroforming, precisely shaped metal microstructures are obtained [6]. The resist is stable to the mostly acid electrolytes even at process times of more than 24 hours.…”