Cutting Silicon for Use Making Solar Cells

Customer:

Major Solar Panel Manufacturer

Background:

Solar cells are becoming ubiquitous along the highways in the United States as they are being used to power everything from road-side phones to cameras monitoring traffic flow. The base material in solar cells is pure silicon, the same material (although of a lower quality) that is used to manufacture integrated circuits. The manufacturing process starts with a silicon ingot approximately 29 inches square and 9 inches thick and ends with a wafer about 4 inches square and .008 inches thick. The first step in the process is cutting the ingot into "bricks" that can be further processed into wafers. Everite was originally approached to cut the ingots into bricks using electrochemically grinding technology. Electrochemical grinding was not well suited to this application but Everite proposed an alternate conventional solution

Manufacturing Challenge:

Silicon is very hard and brittle and is difficult to machine. It is also very abrasive and can destroy the machine it is being processed on if not adequately protected

Solution:

Everite proposed the use of previously owned horizontal machining centers with large diamond blades (27 inch diameter). The application demands a machine with high rigidity because the workpiece is brittle and subject to chipping. The process is also fairly crude in comparison to the capabilities of a typical horizontal machining center application, which was why only used machines were suggested. The abrasiveness of the application would likely cause problems with machine longevity which was another reason for the selection of a used machine. Everite retrofitted the machine to allow for proper coolant flow and machine protection and developed the manufacturing process. Eventually five systems were purchased and put into production.