Swelling of SU-8 structure in Ni mold fabrication by UV-LIGA technique

Abstract

UV-LIGA technique is used to fabricate hot embossing mold of PMMA microfluidic chip. Pre-polished Ni plate serves as electroforming substrate and the micro channel is the only structure to be electroformed in the fabricated mold. The precision of the micro channel strongly depends on the process parameters. Experiments show that the width of micro channel varies with the electroforming time. With the electroforming time of 108, 140 and 160 min, the width of micro channel reduces to 89, 86 and 82% of patterned SU-8 mold respectively, which is caused by swelling of SU-8 in acidic, high temperature electroforming solution. This swelling is the key answer to the slope of the sidewalls of the electroformed structure. This study is beneficial to optimizing microfluidic chip mold design.

Micro-fabricated stylus ion trap

“…The alignment of these deformations indicates that it is caused by swelling of the photoresist during the processing, with less swelling occurring in the gaps between the electrodes. 9 The swelling of the resist is a result of exposure to the high alkaline (Na based) plating baths, particularly at an elevated temperature (50 • C). Swelling also resulted from an increased solvent concentration in the thick resist.…”

“…To achieve a proximity that is relevant to ions used for quantum information, i.e., an ion distance, h 100 μm, from the surfaces, the trap should have features on this scale. In order to fabricate a stylus trap with features of 100 μm, we utilized UV-LIGA (a German acronym for lithography, electroplating, and molding) technology, [8][9][10][11][12] i.e., UV photolithograpy with a thick resist and subsequent metal electroforming with the use of electrodeposition. Using this technique, we have fabricated traps that consist of 150 μm tall structures (see Figs.…”

Microssistemas de análises químicas: introdução, tecnologias de fabricação, instrumentação e aplicações

“…A maior penetrabilidade e o paralelismo desta fonte de radiação garantem a obtenção de microestruturas com grande razão de aspecto (relação entre a altura e a largura do canal). No entanto, uma fonte de luz síncrotron representa um custo elevado e logo o processo foi adaptado para luz ultravioleta (LIGA-UV), com decorrente perda de resolução 35 .…”

Quantitative diffusion and swelling kinetic measurements using large-angle interferometric refractometry

“…3,[34][35][36][37] Exposure to other solvents can also result in film cracking, delamination and damage to microstructures. [38][39][40][41] In this study, we use interferometric refractometry at large incidence angles to demonstrate real-time kinetic measurements of refractive index and thickness of films. The diffusion of water and other solvents into SU-8 photoresist is used to highlight the sensitivity and accuracy of the technique.…”