Patent ID: 8865525

Claim:
A method of making a cavity substrate, comprising: providing a supporting board that includes a sacrificial carrier, a stiffener, an adhesive and an electrical pad, wherein (i) the sacrificial carrier includes a bump and a flange, (ii) the bump is adjacent to and integral with the flange and extends from the flange in a first vertical direction, (iii) the flange extends laterally from the bump in lateral directions orthogonal to the first vertical direction, (iv) the stiffener is attached to the sacrificial carrier via the adhesive between the stiffener and the flange and between the stiffener and the bump, and (v) the electrical pad extends beyond the bump in the first vertical direction and is covered by the bump in a second vertical direction opposite the first vertical direction; forming a coreless build-up circuitry that covers the electrical pad, the bump and the stiffener in the first vertical direction and is electrically connected to the electrical pad; and removing the bump to form a cavity and expose the electrical pad and a portion of the coreless build-up circuitry from a closed end of the cavity, wherein the cavity is laterally covered and surrounded by the adhesive and faces in the second vertical direction.