Traditionally, the ingot was sliced into thin wafers using a 10-tonne wire saw. The basic principle of wire sawing is to feed the ingot into a web of ultra-thin, fast moving wire. The cutting action of the wire is created by dispensing abrasive slurry over the web while the wire is transported in a rapid, back and forth lateral motion. The wire web is, in effect, a single wire being fed from one large spool to another. Depending on the wire diameter, each spool can hold hundreds of kilometers of wire. Current wire saw technology allows for the entire ingot to be sliced simultaneously, thus lowering cycle time and minimizing "kerf" loss.
GYLCOL BASED SILCUT SYNTHETIC FLUID FOR WIRE SAWING
Process Research Products has developed a range of proven synthetic wire saw slicing fluids for the cutting of silicon wafers. These products are suitable for all wire saws. Various abrasives can be mixed with SILCUT to form a slurry. Typical abrasives are silicon carbide (GC). SILCUT is used in conjunction with Silicon Carbide typically GC 1000, 1200 or GC 1500. SILCUT, when mixed thoroughly with silicon carbide, produces a soft settling glycol based slurry.
Product Benefits / Features:
- Excellent thermal stability
- Stable slurry viscosity in use
- Good lubricity
- Water soluble
- Easily cleaned (non-staining)
- Biodegradable and easy to dispose
A more recent innovation is to cut the wafers with electroplated diamond coated wire on a wire saw machine. For this operation, we recommend our water based surfactant/coolant AQUASLICE.
AQUASLICE is a concentrated water soluble, non-foaming coolant designed for diamond wire cutting operations on both monocrystalline and multicrystalline silicon. AQUASLICE is the result of an extensive R&D development project using a state of the art diamond multi wire saw. This unique formulation keeps the diamond wire free from swarf buildup, improving cut rate and wire life. AQUASLICE is compatible with continuous coolant recovery using mechanical candle-type filtration systems. AQUASLICE can be used for bricking, squaring and wafering applications.
Product benefits/features compared to cutting with slurry:
- Very clean cutting process.
- Cost down.
- Cuts much faster.
- Better TTV and flatness.
- Wafers are easier to clean.
- Better yield.
- Lower subsurface damage.
- Low foam.
- Low wire wear.
- Prevents loading of diamond wire.
- Can be used in batch mode or at lower concentration in a constant loss configuration.
- Promotes slow, soft settling of swarf, ideal for coolant recovery using mechanical filtration.
- Significant increase in filtration throughput versus competitors for efficient coolant recycling.