Devices and methods for assembling a connector are provided herein. In one aspect, an example method of assembly includes positioning an insert frame having an applicator portion supporting electrode contacts within an enclosure; attaching the electrode contacts to a circuit board substrate within the enclosure; forming an underfill layer by injecting a hardenable fluid medium through the applicator portion to fill a semi-confined space between the insert frame and the circuit board substrate; and detaching the applicator portion and applying an overmold. The applicator portion includes one or more lumens extending from an inlet opening to one or more exit openings to facilitate flow of fluid medium to desired locations. The inlet opening may be disposed on a portion of the applicator extending above the insert frame and have a diameter substantially larger than the exit opening to allow for fluid injection using an oversized injection nozzle.