Experiment design and UV-LIGA microfabrication technology to study the fracture toughness of Ni microstructures

Abstract

One of the major difficulties faced by MEMS researchers today is the lack of data regarding properties of electroplated metals or alloys of which microstructures and microdevices are fabricated, especially in LIGA technology. These mechanical properties cannot be extrapolated from macro-scale data without experimental verification. Therefore, study on material properties of microfabricated structures is of vital importance to the development of LIGA technology and to its industrial applications. This paper reports an experiment scheme and UV-LIGA microfabrication technology to study the fracture toughness of nickel micro specimens. The devised testing mechanism demonstrated compatibility with the fabricated samples and capability of performing the desired experimentation by generating resistance-to-fracture values of the nickel specimens. The same experiment scheme and sample fabrication technology can be used in future work to study the fracture toughness values for LIGA fabricated samples in various metals and alloys.

A quantitative study on the adhesion property of cured SU-8 on various metallic surfaces

“…With the recent progress made in UV lithography of SU-8, the quality of the microstructures obtained is also improved dramatically. A variety of microdevices made from pure metals, alloys, or metal/polymer composites as structural materials have been reported (Dai et al 2005;Lee et al 2003;Yang et al 2003;Ling and Lian 2000;Konaka and Allen 1996;Lorenz et al 1998c) using the SU-8 UV-LIGA technique.…”

Thermal Shock Performance of DBA/AMB Substrates Plated by Ni and Ni–P Layers for High-Temperature Applications of Power Device Modules

“…The cracking of the Ni–P layer might be explained by the differing fracture toughness between the Ni–P electroless and electroplated Ni layers. The fracture toughness of a crystalline Ni–P electroless plating layer is between 1.1 and 2.1 MPa·m 1/2 [32,33,34], while an electroplated Ni layer is around 53 MPa·m 1/2 [31]. High fracture toughness is related to crack initiation resistance and slow crack growth under the same stress conditions [36].…”

Prototyping and Production of Polymeric Microfluidic Chip

“…It has been a promising technology for industrial-scale commercialization [40,41]. The typical process methods follow the consequential steps below: 1) the photoresist (AZ or epoxy resin SU-8) is firstly evenly coated on the silicon wafer substrate along with the subsequent baking process; 2) a pre-prepared photomask with the desired patterns is placed on the top surface of the photoresist at a good alignment manner for further irradiation exposure; 3) the exposed areas is removed/ remained chemically using developer (depending on the type of photoresist), where the patterns are transferred to silicon wafer from mask and the dimensional accuracy of patterns can be controlled by lithography parameters (exposure time and exposure dose); 4) seed layers of adhesive layer (Ti/Cr) and conductive layer (Au/Ni) are sputtered onto the structured photoresist surface for metallization; 5) the following step is electroforming for fabricating a microstructured mold insert, where the metallized patterns on silicon wafer serve as a cathode for nickel deposition; after electroforming, a electroformed replica is relived via silicon chemically etching and photoresist is chemically removed; the final replica can be used as a mold insert; 6) such an electroformed mold insert can be used as a master for replication of microfluidic chips by microinjection molding process [42]. Figure 7 details the specific process steps of mold insert fabrication in various microstructuring technologies assisted by electroforming.…”