Capabilities
Precision Grinding & Optical Polishing
Multi-stage grinding, lapping, and optical polishing for fused quartz, sapphire, and precision ceramics, with surface specifications reviewed case by case.
Precision Grinding, Lapping & Optical Polishing
For semiconductor process components and optical elements, surface finish is not merely cosmetic — it can affect contamination risk, optical transmission, and bonding reliability. Tuguan Semiconductor reviews surface finishing requirements from coarse grinding through optical polishing based on drawings and inspection scope.
Process Stages
Stage 1 · Coarse Grinding
Diamond cup wheels on CNC surface grinders remove stock rapidly while maintaining flatness within 5–10 μm. This stage establishes the gross geometry and removes saw damage from sliced blanks.
| Parameter | Value |
|---|---|
| Material removal rate | 0.1–0.5 mm/pass |
| Surface roughness after | Ra 0.8–1.6 μm |
| Flatness after | 5–10 μm |
| Wheel specification | D46–D107 resin-bond diamond |
Stage 2 · Fine Grinding (Precision Grinding)
Fine-grit diamond wheels (D15–D25) reduce subsurface damage and bring the surface to near-lapping quality.
| Parameter | Value |
|---|---|
| Surface roughness after | Ra 0.2–0.4 μm |
| Flatness after | 2–5 μm |
| Subsurface damage depth | < 2 μm |
Stage 3 · Lapping
Double-side lapping with alumina or diamond slurry achieves the flatness and parallelism required for precision wafer carriers, windows, and substrates.
| Specification | Single-Side | Double-Side |
|---|---|---|
| Flatness | < 2 μm | < 1 μm |
| Parallelism (TTV) | < 3 μm | < 2 μm |
| Surface roughness | Ra 0.05–0.1 μm | Ra 0.05–0.1 μm |
| Max plate size | 500 × 500 mm | Ø 400 mm |
Process control: Slurry concentration, plate pressure, and rotational speed are continuously monitored. All slurries use ultra-pure DI water as carrier fluid to prevent metallic contamination.
Stage 4 · Chemical-Mechanical Polishing (CMP) / Optical Polishing
Final optical-quality polishing uses a process route selected by material and surface requirement. Coating, bonding-interface, and optical-surface specifications should be reviewed case by case before quotation.
| Specification | Precision Polish | Optical Polish |
|---|---|---|
| Surface roughness | Specified per application | Reviewed with measurement method |
| Flatness (surface form) | Specified per application | Reviewed with inspection method |
| Scratch-dig specification | Optional | Reviewed for optical-grade orders |
| Subsurface damage | Reviewed by process route | Reviewed by process route |
| Max clear aperture | Reviewed by part size | Reviewed by part size |
Material-Specific Considerations
| Material | Lapping Abrasive | Polishing Slurry | Notes |
|---|---|---|---|
| Fused quartz | Al₂O₃, then diamond | CeO₂ or SiO₂ colloidal | Surface finish reviewed by drawing and measurement method |
| Synthetic fused silica | Diamond | Colloidal SiO₂ | OH content affects polishing rate |
| Sapphire (C-plane) | Diamond (mandatory) | Diamond + Al₂O₃ | Hard axis; slow removal rate |
| Sapphire (A/R-plane) | Diamond | Diamond + CeO₂ | Anisotropic hardness aids polishing |
| Alumina 99.5% | Diamond | Diamond micro-powder | Porous structure limits achievable Ra |
| Silicon nitride | Diamond | Diamond micro-powder | Toughest ceramic to polish optically |
| Boron nitride | SiC or Al₂O₃ | Al₂O₃ or SiO₂ | Soft; risk of smearing at high pressure |
Cleaning & Contamination-Control Review
All polishing and lapping operations are conducted with:
- Water-based cleaning and rinse planning selected by material and application
- Material-aware pad and slurry selection to reduce cross-contamination risk
- Slurry and rinse controls reviewed by surface requirement
- Clean packaging requirements confirmed before quotation based on the application cleanliness target
Surface Inspection Capabilities
Inspection scope for polished components is agreed before production:
| Instrument | Parameter | Resolution |
|---|---|---|
| White-light interferometer | Flatness, surface form | Method-dependent |
| Contact profilometer | Ra, Rq | Method-dependent |
| AFM (atomic force microscope) | Low-roughness review | Method-dependent |
| Nomarski DIC microscope | Scratch-dig, surface defects | Standard to be agreed |
| Calibrated CMM | Dimensional tolerances | Per inspection plan |
Lead Time Factors for Polished Components
Lead time depends on material, part size, surface specification, measurement method, and inspection documentation. Large-format optical parts and tight surface requirements should be reviewed before quotation.