Self-alignment in the stacking of microchips with mist-induced water droplets

Bo Chang, Veikko Sariola, Mirva Jääskeläinen, Quan Zhou

    Research output: Contribution to journalArticleScientificpeer-review

    24 Citations (Scopus)


    This paper reports a novel and versatile water droplet self-alignment technique where the water is delivered in mist form onto the assembly site. The droplet forming process has been carefully investigated using machine vision, where each individual droplet on the microchip surface can be identified and the volume per surface area can be calibrated at a specific time. The result reveals that the volume of water droplets on the assembly surface grows linearly as a function of time. Self-alignment based on the mist-induced droplets has been studied, where a robotic microgripper is used to deliver the microchips on the assembly site. The paper also investigates the maximum tolerance of the initial placement error in stacking SU-8 chips 200 × 200 × 70 μm in size, and the possibility of stacking two SU-8 chips of different dimensions using the proposed self-alignment technique. Moreover, self-alignment of chips on hydrophilic/hydrophobic patterns covered by mist-induced water droplets has been studied. The experimental results indicate that this novel self-alignment technique is very promising. Furthermore, a statistical model has been used to validate the experimental results.

    Original languageEnglish
    Article number015016
    JournalJournal of Micromechanics and Microengineering
    Issue number1
    Publication statusPublished - Jan 2011
    Publication typeA1 Journal article-refereed

    ASJC Scopus subject areas

    • Mechanical Engineering
    • Electrical and Electronic Engineering
    • Mechanics of Materials
    • Electronic, Optical and Magnetic Materials


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