METHOD AND APPARATUS FOR DISPENSING SMALL AMOUNTS OF LIQUID MATERIAL

摘要

Apparatus and methods for dispensing droplets of liquid or viscous material. The apparatus generally comprises a valve operated dispenser (10) and a control (128', 129) for moving the valve member (42') with respect to a valv e seat (38') in rapid succession. This rapidly accelerates liquid or viscous material in a stream from the dispenser outlet and immediately breaks the stream into a minute droplet. Various embodiments of the valve seat (38') include both rigid valve seats and resilient valve seats. Resilient valve seats are especially useful for dispensing solder pastes as they can prevent material flaking, compacting and clogging conditions. Low friction polymer o r plastic material for dispenser components such as the valve member (42') and outlet structure (40') can also prevent such problems.