Tungsten‑wire diamond wire: A technological breakthrough ushers in a new era of cutting.

Amid the accelerating trend in the photovoltaic industry toward “large‑size, thin‑wafer” formats, cutting technology has emerged as a critical bottleneck limiting cost reduction and efficiency gains. Conventional carbon‑steel diamond wire, with its wire diameter approaching physical limits, can no longer meet the dual demands of rising silicon material costs and improved cutting efficiency. In contrast, tungsten‑wire diamond wire, leveraging its unique material properties and breakthrough manufacturing processes, is ushering in a new era of photovoltaic cutting technology with disruptive advantages: finer wire diameters, superior tensile strength, and reduced wear.

Technological Evolution: An Inevitable Transition from Carbon Steel to Tungsten Filaments

Since its introduction to the photovoltaic industry in 2010, diamond wire cutting has rapidly replaced slurry cutting as the dominant process. Its core principle involves using a steel wire substrate to drive high‑speed motion of diamond micro‑powder particles, achieving silicon wafer slicing through abrasive grinding. However, the physical limitations of carbon‑steel wire substrates are becoming increasingly apparent: when the wire diameter falls below 35 μm, tensile strength plummets, leading to a sharp rise in wire breakage and resulting in silicon material losses as high as 40% during cutting. For instance, a leading silicon wafer manufacturer once experienced daily production losses exceeding 200,000 wafers due to carbon‑steel wire breakage.

The introduction of tungsten wire offers a breakthrough to this predicament. As a refractory metal with a melting point as high as 3,410°C, tungsten wire boasts a tensile strength exceeding 5,000 MPa—three times that of carbon steel—and an elastic modulus of 410 GPa, 60% higher than carbon steel, enabling it to withstand cutting stresses at significantly higher wire speeds. More importantly, by alloying with elements such as lanthanum and rhenium, tungsten wire can achieve an optimized grain‑orientation structure, maintaining stability even when the wire diameter is reduced to 21 μm. In 2025, San Chao New Materials will launch a 21‑μm tungsten‑wire diamond wire that, in laboratory tests, has demonstrated a reduction of 0.03 mm in single‑wafer silicon material loss—equivalent to annual silicon‑material cost savings exceeding RMB 200 million for a 10 GW production capacity.

Technological Breakthrough: Bridging the Gap from Laboratory to Industrialization

The industrialization of tungsten‑wire diamond wire faces three major technical barriers: billet drawing, pre‑treatment processes, and uniform sand‑coating. Conventional carbon‑steel wire is produced via cold drawing, achieving a yield of up to 85%; in contrast, tungsten wire must be hot‑drawn at temperatures as high as 1,600°C, and fluctuations in the performance of graphite‑based lubricants readily lead to wire breakage, resulting in an industry‑average yield of only 55%. By developing a “multi‑stage rotary forging plus gradient annealing” process, Xiamen Tungsten has reduced the grain size of tungsten billets to below 0.5 μm, enabling a yield exceeding 70% for 35‑μm tungsten‑wire billets—reaching an internationally leading level.

Breakthroughs in the pre‑treatment stage are equally critical. Carbon steel wire is pre‑cleaned using hydrochloric acid pickling, whereas tungsten wire, after high‑temperature drawing, readily forms an oxide layer on its surface; only a combined “amino sulfonic acid plus ultrasonic cavitation” treatment can ensure that the nickel‑plated coating achieves adhesion strength exceeding 15 MPa. The “pulsed electrochemical cleaning” technology developed by Jucheng Technology reduces cleaning time from 120 seconds to 45 seconds, tripling the production capacity per wire.

The diamond‑wire dressing process is pivotal to cutting precision. The finer the tungsten wire diameter, the more stringent the requirements for uniform distribution of diamond grains. Gaoce Shares employs a “magnetic‑field‑assisted dressing” technique that uses precisely controlled electromagnetic field strength to align 0.5‑μm diamond particles in a single layer, keeping blade‑outstanding height variation within ±0.2 μm. This reduces silicon wafer TTV (total thickness variation) from 8 μm to 5 μm and boosts the yield of Grade‑A wafers by 12 percentage points.

Market Transformation: Industrial Upgrading from Substitution to Leadership

The economic advantages of tungsten‑wire diamond wire are rapidly becoming apparent. Taking a 36‑μm wire diameter as an example, the material consumption per gigawatt for tungsten‑wire wire is 10% lower than that of carbon‑steel wire. Coupled with fluctuations in silicon‑material prices, when silicon‑material prices exceed RMB 80/kg, tungsten‑wire wire can reduce wafer‑slicing costs by RMB 0.015/W. According to estimates, global demand for tungsten‑wire diamond wire will reach 137 million kilometers by 2025, with the market size surpassing RMB 9.6 billion and a compound annual growth rate of 126%.

The industry landscape is being reshaped accordingly. Xiamen Tungsten, leveraging its vertically integrated “tungsten ore–APT (ammonium paratungstate)–tungsten wire–diamond wire” value chain, aims to achieve a tungsten wire and ribbon production capacity of 180 million kilometers by 2025, capturing 60% of the global market share. Meanwhile, Jucheng Technology, through joint testing with silicon wafer leaders such as LONGi and Zhonghuan, has introduced 21-μm tungsten wire into N-type TOPCon cell production lines, reducing per‑cell cutting time from 3 minutes to 2.2 minutes and boosting equipment utilization by 25%.

Technology spillover effects are also beginning to emerge. In the semiconductor sector, tungsten‑wire diamond wire has been successfully deployed for cutting 8‑inch silicon wafers, with scribe‑line depths reduced by 40% compared to carbon‑steel wire. In magnetic‑material processing, its superior corrosion resistance extends the coolant‑change interval by a factor of three and lowers the per‑ton material‑processing cost by 18%.

Future Prospects: Exploring the Limits from Microns to Nanometers

The evolution of tungsten‑wire diamond wire continues. San Chao New Materials is developing an 18‑μm ultra‑fine tungsten wire, leveraging “nano‑twinning strengthening” technology to push its tensile strength beyond 6,000 MPa; meanwhile, Xiamen Tungsten is exploring a “tungsten‑molybdenum composite matrix,” using molybdenum’s ductility to offset tungsten’s brittleness and further reduce the wire diameter to 15 μm. At the same time, intelligent manufacturing is emerging as a new trend: Gaoce Shares’ “dark factory” employs an AI‑powered visual inspection system, cutting the defect rate per kilometer from five to 0.3 and achieving product consistency of 99.97%.

From 35 μm to 21 μm, tungsten‑wire diamond wire has accomplished in a decade what carbon‑steel wire took thirty years to achieve. This material‑driven revolution in cutting technology has not only reshaped the cost structure of the photovoltaic industry chain but has also enabled Chinese manufacturing to secure a stronger voice in the realm of high‑end precision machining. As wire diameters enter the nanoscale era, tungsten‑wire diamond wire is poised to continue writing the industry’s legend of “breaking surfaces with a thread.”

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