Dam and fill dispensing is used to encapsulate components and give them a molded-like finish. This process is typically used where the production volume does not justify purchasing mold equipment.
To create a dam, a rectangle of fluid is dispensed around a die. This fluid is typically high viscosity in nature, so once it is dispensed, it does not flow. The skill in dispensing dams is to get a knit line at the start of the dispensed line to blend smoothly with the end of the rectangular dispense pattern.
Liquid fill encapsulants are dispensed at high speed over a die and wirebonds, to encapsulate them.
With the right dispensing program, components can be encapsulated with a specification of 75 microns total thickness variation over the die and wirebonds.