A Development of Dispenser for High-Viscosity Liquid and Pick and Place of Micro Objects Using Capillary Force

In this paper, we describe the development of a needle based dispenser for high-viscosity liquid, and pick & place of micro objects using capillary force. Recently, miniaturization of portable devices and their electronic parts has been remarkable. So we think that there are a lot of needs for micro manipulation for making more complex and smaller devices. There are a lot of possibilities to manipulate complex-shaped micro objects by using liquid because it changes its shape flexibly according to the shape of the contact surface. We have developed a unique surface mounting technology which is based on a movable shaft driven by a piezoelectric linear motor. We can simply apply high-viscosity liquid drops by stamping the wet tip of the shaft on a substrate, and we confirm that the device is able to apply a liquid the viscosity of which is about 1200Pas. We have studied the relation between viscosity and diameters of applied liquid drops via several experiments. We have also conducted interesting experiments in which we pick and place some small and complex-shaped objects using capillary force. We confirmed that if capillary force between the shaft and micro object is larger than that between the substrate and the micro object, we are able to place a chip-capacitor weighing below 1 mg. This simple method is very effective because any shaped object can be mounted. However, fast control and accurate control of the shaft are needed for efficient production and accurate mounting. To realize this, we developed a PID controller for the dispenser with an optical liner encoder with a resolution of 30 nm. We confirm that settling time becomes less than 50 ms when the shaft moves 5 mm with 1 micrometre accuracy.