New Concept for Fabrication and Inspection of Micro-Objects
◆Self-Alignment of Microparts Using Liquid Surface Tension

Many fabrication methods of microparts have been developed and systems composed of microparts of which materials and shapes differ have been investigated. In order to realize such systems as industrial products, an assembly technique of the microparts for mass production is necessary with alignment being a very important task in the assembly.

The purpose of this research is to establish a self-alignment method for microparts assembly using liquid surface tension in the air. The alignment method does not need precision servomechanisms. It is suitable for mass production and free from thermal deformation of microparts. In this study, first, the effects of droplet volume, high wettability area pattern on restoring force and alignment accuracy were examined and evaluated. Next, self-alignment and bonding of microparts using adhesive surface tension for microparts assembly were carried out and evaluated. The experimental results show that the averages of alignment errors using the adhesive and the 1mm×1mm×0.15mm microparts are smaller than 2m in the translational directions and 0.2 degrees in the rotational direction. In addition, the self-alignment of a group of microparts at a time (Fig.1.[Video]) and the self-standing using liquid surface tension and vibration force (Fig.2.[Video])were introduced. Their performances were evaluated experimentally. The experimental results show that the reliability of the introduced self-alignment method of a micropart group is very high by using the improved microparts and the proposed self-standing method is useful.

Fig.1 Self-alignment of a group of microparts at a time [Video: Click the figure]

Fig.2 Self-standing using liquid surface tension and vibration force [Video: Click the figure]

Key papers

[1]
Kaiji Sato, Keunuk Lee, Masahiko Nishimura, Kazutoshi Okutsu: Self-Alignment and Bonding of Microparts Using Adhesive Droplets, International Journal of Precision Engineering and Manufacturing, Vol.8, No.2, (2007) pp.75-79.
[2]
Sato, K., Hoshino, S., Kobayashi, S.: Self-alignment of Microparts Using Liquid Surface Tension - Extension of Function by Vibration Force: Self-alignment of a Group of Microparts and Self-standing, Proc. of ASPE's 19th Annual Meeting, (2004) pp.325-328.
[3]
Kaiji SATO, Kentaro ITO, Seiichi HATA and Akira SHIMOKOHBE: Self-alignment of Microparts Using Liquid Surface Tension -Behavior of Micropart and alignment characteristics, Precision Engineering, Vol.27, No.1, (2003) pp.42-50.
[4]
Kaiji SATO, Seiichi HATA and Akira SHIMOKOHBE: Self-alignment for Microparts - Assembly Using Water Surface Tension, Proc. of SPIE, MICRO/MEMS'99 (Queensland, Australia), (1999) pp.321-329.