Why Diamond Wire Moved from Carbon Steel to Tungsten
The consumable battle in wafer slicing is really a battle over kerf loss. Every micron shaved off the wire diameter adds a meaningful number of wafers per ingot. In the carbon-steel era the lower limit was set by substrate strength: the thinner the wire, the more likely it breaks under the same tension, and one break costs far more than the wire saved.
What Tungsten Changed
Tungsten wire carries markedly higher tensile strength than high-strength carbon steel at the same diameter. That means it can be drawn thinner while keeping breakage under control. For a slicing house, 24–30 µm tungsten-core wire does not lower the unit price of consumables — it raises wafers per ingot and cuts silicon loss, which is the precondition for thinner wafers and larger ingots.
The Difficulty Is the Coating, Not the Drawing
Tungsten wire itself comes from powder metallurgy and drawing. The real barrier is electroplating: uniform diamond adhesion, sufficient retention and low coating stress. Get any of the three wrong and a fine wire will shed grit, expose substrate or fail locally at speed. That is why diameter tolerance, coating thickness and diamond size distribution say more about process capability than the smallest diameter a supplier can quote.
What to Ask When Buying
Ask four things: the diameter tolerance band, batch-to-batch spread of breaking force and elongation, diamond grit size and surface density, and spool length with the number of joints. Those four determine breakage rate and cost per cut — far more than a nominal diameter figure.