Galvanic isolation device
A galvanic isolation device includes a first integrated circuit (IC) die that has communication circuitry formed in a circuit layer below the top surface. A first conductive plate is formed on the IC die proximate the top surface, and is coupled to the communication circuitry. A dielectric isolation layer is formed over a portion of the top surface of the IC after the IC is fabricated such that the dielectric isolation layer completely covers the conductive plate. A second conductive plate is juxtaposed with the first conductive plate but separated by the dielectric isolation layer such that the first conductive plate and the second conductive plate form a capacitor. The second conductive plate is configured to be coupled to a second communication circuit.
1. A method of fabricating a galvanic isolation device, the method comprising:
fabricating a first integrated circuit (IC) including first conductive plates proximate a surface of the first IC and coupled to first circuitry within the first IC;
placing a dielectric isolation layer, including a die attach material, on a portion of the surface of the first IC, the dielectric isolation layer completely covering the first plates;
placing second conductive plates on the dielectric isolation layer; and
with the die attach material, mounting a second IC to the first IC, a first one of the second conductive plates being juxtaposed with a first one of the first conductive plates separated from the first one of the first conductive plates by the dielectric isolation layer to form a first capacitor, and a second one of the second conductive plates being juxtaposed with a second one of the first conductive plates and separated from the second one of the first conductive plates by the dielectric isolation layer to form a second capacitor, and the second conductive plates being proximate a surface of the second IC;
in which placing the dielectric isolation layer includes selectively printing the die attach material to form air gaps between the first and second capacitors.
2. The method of claim 1 , wherein placing the second conductive plates includes depositing a conductive material on the dielectric isolation layer using a three dimensional (3D) printing process.
3. The method of claim 1 , wherein placing the dielectric isolation layer includes performing a three dimensional printing process, and the dielectric isolation layer covers: an edge of the first IC; and the portion of the surface of the first IC.
4. The method of claim 1 , wherein placing the dielectric isolation layer includes performing micro-drop deposition.
5. The method of claim 1 , wherein placing the dielectric isolation layer includes: placing one or more layers of liquid material on the surface of the first IC, and allowing the layers to harden before placing the second conductive plates.
6. The method of claim 1 , wherein placing the dielectric isolation layer includes applying a liquid that hardens after placing the second conductive plates.