Key process steps

Substrate preparation

Raw material: High purity tungsten plate (purity ≥ 99.95%) is used, with a common thickness of 0.1mm~50mm.

Pre processing: Obtain approximate dimensions through rolling or forging to eliminate internal stress.

Rough grinding

Equipment: Surface grinder (diamond grinding wheel) or double-sided grinder.

Parameters: Grinding wheel particle size # 80~# 200, removing surface oxide layer and macroscopic unevenness.

Fine grinding

Grinding wheel particle size: # 400~# 800, surface roughness Ra ≤ 0.4 μ m.

Coolant: Deionized water or specialized cutting fluid must be used to avoid contamination.

Polishing

Mechanical polishing: Diamond polishing paste (0.5~3 μ m particle size)+lint free polishing disc, Ra can reach 0.05 μ m.

Electrolytic polishing: suitable for ultra mirror surface requirements (Ra<0.01 μ m), requiring control of voltage and electrolyte formula (such as NaOH solution).

Cleaning and testing

Ultrasonic cleaning (acetone+alcohol) to remove residual abrasives.

Testing items:

Surface roughness (white light interferometer)

Flatness (laser planimeter, ± 0.005mm/m ²)

Microscopic defects (electron microscopy).

Technical difficulties and solutions

Question                       Reason                                                                                                    Solution

Surface scratches          Tungsten has high hardness and is embedded with abrasives              Replace finer grinding wheels in stages and strengthen cleaning

Edge cracking               Tungsten has high brittleness                                                                 Chamfering pretreatment to reduce feed rate

Stain                              Polishing heat causes surface oxidation                                                 Inert gas protection polishing or subsequent acid washing (such as HF+HNO ∝)

Performance parameters (example)

Grade of smoothness:

Ordinary polishing: Ra 0.1~0.4 μ m (similar to stainless steel mirror panels)

High precision polishing: Ra ≤ 0.025 μ m (optical grade)

Tolerance control:

Thickness tolerance: ± 0.005mm (10mm thick plate)

Parallelism: ≤ 0.01mm/100mm

Main application scenarios

Semiconductor equipment

The electrostatic suction cup (ESC) substrate used for wafer processing requires ultra-high flatness to prevent wafer deformation.

Medical shielding

The tungsten aperture (multi leaf collimator) in radiotherapy equipment is affected by surface smoothness, which affects radiation scattering.

Vacuum coating

Evaporation boats or sputtering target liners must have defect free surfaces to ensure coating uniformity.

Research instruments

The flatness of the X-ray diffractometer sample stage affects the detection accuracy.