LORD has developed a new epoxy adhesive to temporarily join silicon ingots to a clasping fixture for wafer slicing. LORD 781 is a two-component, thixotropic adhesive system that helps ingot manufacturers to minimize operating costs, enhance utilization and decrease waste. It is also a high viscous material that minimizes adhesive flow to prevent ingot contamination.
The adhesive can bond ingots of different lengths to allow easy slicing and reduce waste. The new silicon ingot bonding material emits low odor and offers exceptional adhesion to various surfaces and provides high bond strength within 12 to 16 hours at room temperature.
The ingot slicing process involves bonding of multiple ingot blocks on a glass, followed by mounting the connected blocks onto the wire sawing tool. The integrated ingot will be cut into a slice or wafer by using a steel wire and cutting liquid. LORD’s new epoxy adhesive connects and fills the spaces between the ingots. It minimizes the movement produced by the steel wire that interacts with the ingot gap. This leads to wire breakages and excess waste of about four to six silicon ingot slices for each gap. Generation of more ingot waste also increases repair time and cost. The process can take about 20 minutes for reorganizing the sawing wire and an additional nine hours for repeating the cutting operation.
LORD 781 is used as a plaster to adhere ingot to ingot and enhance wire saw stability at higher temperatures. The new ingot bonding material provides considerable benefits to the solar market: high cost savings and decreased waste creation during the slicing process. It can also reduce warping of silicon slices and Total Thickness Variation (TTV).
Source: http://www.lord.com/