Systems, method and apparatus for curing conductive paste
One embodiment can provide a system for curing conductive paste applied on photovoltaic structures. The system can include a wafer carrier for carrying a plurality of photovoltaic structures and a heater. The wafer carrier can include a surface element that is in direct contact with the photovoltaic structures and is substantially thermally insulating. The heater can be positioned above the wafer carrier. The heater can include a heated radiation surface that does not directly contact the photovoltaic structures.
1. A method for curing conductive paste applied to two adjacent photovoltaic structures, the method comprising:
placing the two adjacent photovoltaic structures on a wafer carrier, wherein the two photovoltaic structures are coupled in a cascaded manner by a conductive paste, where two adjacent edges of the two photovoltaic structures overlap, wherein the wafer carrier includes a surface element that is in direct contact with the photovoltaic structures and is substantially thermally insulating, and wherein the wafer carrier is placed on a conveyor; and
controlling movement of the conveyor to position the wafer carrier to a vicinity of a heating block such that a heated radiation surface of the heating block radiates heat to the photovoltaic structures for a predetermined duration to cure the conductive paste.
2. The method of claim 1 , wherein the surface element of the wafer carrier is made of polybenzimidazole (PBI) plastic.
3. The method of claim 1 , wherein the surface element includes a number of components separated by air gaps to allow an individual component to expand when heated.
4. The method of claim 1 , wherein the heated radiation surface is maintained at a predetermined temperature between 200 and 600° C., and wherein the predetermined duration is between 25 and 60 seconds.
5. The method of claim 1 , wherein the heated radiation surface of the heating block is coated with a substantially dark colored coating.
6. The method of claim 5 , wherein the substantially dark colored coating includes an anodizing coating or a high-emissivity coating, and wherein a thickness of the dark colored coating is between 1 and 100 microns.
7. The method of claim 5 , wherein other surfaces of the heating block are polished or covered with a layer of thermal insulation material.
8. The method of claim 1 , wherein the heating block is made of a material having a thermal conductivity of at least 50 W/(m·k).