Liquid resins are used in two main ways in encapsulations processes. The first methods is glob top and dam & fill alternatively known as frame & fill. The second method is Casting and Potting that can be used to encapsulate sensitive electronics as well as opto-electronic devices. In the case of LEDs they can be both cast or potted.
When an LED is cast, liquid resin is poured into the LED chamber and cured into the shape of the cavity. This produces a stand-alone device which can then become a component in another printed circuit board assembly. In the potting process, LEDs are already wired and connected to a circuit board or substrate. The circuit board or substrate usually already has a frame or cavity which is then filled with a liquid resin and then cured. This results in a group of LEDs set in a ready-to-go circuit board or substrate.