Dispensing discrete dots of material is one of the most basic of dispense applications and yet still manages to present its own unique challenges. The smaller the dots, the better the process control must be. Where applicable, a standoff-foot can help yield consistent results, but often that is not a viable solution.
Dots as small as 300 picoliters are possible, depending on material rheology. The smaller the target, the more critical the height above the substrate, especially when no standoff foot can be used. Precise information regarding tip position and substrate Z location (as well as X and Y) become crucial for success. Vision alignment becomes key for high speed, accurate throughput.
Typical dot dispenses include SMD adhesive, genetic (DNA) arrays, microfuidic test slides, solder paste conductive adhesives, epoxy microdots, grease lubricants, CAs, and many others.
At a certain point a dot dispense ceases to be a dot dispense and transitions to a potting dispense!