Premium
Study of SU‐8 to make a Ni master‐mold: Adhesion, sidewall profile, and removal
Author(s) -
Kim SungJin,
Yang Haesik,
Kim Kyuwon,
Lim Yong Taik,
Pyo HyeonBong
Publication year - 2006
Publication title -
electrophoresis
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.666
H-Index - 158
eISSN - 1522-2683
pISSN - 0173-0835
DOI - 10.1002/elps.200500773
Subject(s) - photoresist , mold , fabrication , materials science , molding (decorative) , embossing , microfluidics , electroplating , adhesion , aspect ratio (aeronautics) , replication (statistics) , layer (electronics) , composite material , capillary action , nanotechnology , optoelectronics , statistics , medicine , alternative medicine , mathematics , pathology
Abstract For disposable microfluidic devices, easy and inexpensive fabrication is essential. Consequently, replication of microfluidic devices, using injection molding or hot embossing, from a master‐mold is widely used. However, the conventional master‐mold fabrication technique is unsatisfactory in terms of time and costs. In this regard, direct Ni growth (electroplating) from a back plate is promising when the photoresist is well‐defined. Here, we demonstrate the use of SU‐8 as a photoresist to define the Ni‐growth region. We accomplish this application by focusing on the adhesion, the sidewall profile, and the removal of SU‐8: the adhesion is enhanced by controlling the exposure dose, the soft‐baking time, and by choosing the adhesion‐promoting layer; the sidewall profile is regulated by selecting the intensity of each exposed wavelength, showing an aspect ratio of up to 20.9; and, easy removal is achieved by choosing a proper photoresist‐stripper. Using the master‐mold fabricated by this method, we test the mechanical stability of the features according to the aspect ratio and length; in the hot embossing process, the features are stable in the aspect ratio of up to 5.8 at a length of 200 µm. In addition, the plastic devices fabricated from this method are applied to the passive stop valves, showing a capillary pressure (−0.2 to −7.2 kPa).