Simulations for a novel fluid dispensing technology based on gas-liquid slug flow

The fluid dispensing is one of the key technologies in electronic packing. A novel approach of non-contact fluid dispensing has been proposed based on the principle of gas-liquid two-phase flow. In view of gas-liquid two-phase dynamics, the flow pattern of slug flow can be obtained stably in the microchannel as the flow rate ratio between the gas and liquid is in an appropriate range. The slug flow can generate fluid droplets and gas bubbles and spray them out of the nozzle with uniform interval, accurate volume, good consistency, high controllability and no back haul. This paper carried out the numerical simulation to investigate the gas-liquid two-phase flow in the microchannel for the adhesive dispensing. A 2-D model of microchannel with a diameter for 0.04 mm was established and meshed. The gas-liquid slug flow emerges after iterating over 1 million steps with the gas flow rate for 0.1 m/s, the water flow rate for 0.05 m/s. The wetting property controlled by the contact angle had been discussed to present different liquid materials application. The poor wetting of liquid benefited for conforming droplets shape and avoiding droplets crashing and back haul. While the gas flow rate decreased, the length of liquid droplet and gas bubble increased and decreased, respectively and the total numbers of bubble and droplet decreased in one period. This indicated the fluid parameters have a high relationship with the quantity and volume of droplet.