Lapping Alkali-Free Glass – Alkali-Free Glass (CTE 3.2 x 10^-6 /K, 350 nm – 2.0 um); Lapping to flatness 1 – 3 um. No minimum order; DFM review included with every RFQ.
Ask any process engineer what makes alkali-free glass difficult and the answer is specific: thin sheets below 0.3 mm demand carrier-supported handling through every step. Our lapping line is tooled around exactly that – cast-iron lap plates with boron carbide and alumina slurries – holding flatness 1 – 3 um on parts from 0.2 – 40 mm thick.
Specification envelope
| Material | Alkali-Free Glass (AF32 / EAGLE-class display glass) |
|---|---|
| Thermal expansion (CTE) | 3.2 x 10^-6 /K |
| Service temperature | 600 C (Tg 717 C) |
| Transmission range | 350 nm – 2.0 um |
| Density | 2.43 g/cm3 |
| Knoop hardness | 590 kg/mm2 |
| Refractive index | 1.51 @ 587 nm |
| Stock thickness | 0.10 – 1.1 mm |
| Maximum blank size | 400 x 300 mm |
| Process | Lapping |
| Working tolerance | flatness 1 – 3 um |
| Minimum feature | thickness +/-0.003 mm |
| Surface finish | Ra 0.2 – 0.6 um matte |
| Thickness window | 0.2 – 40 mm |
| Edge condition | not applicable |
| RFQ inputs | PDF/DXF/STEP drawing, quantity brackets, surface and edge spec |
Capabilities and limits
The core strength of Lapping is restoring flatness and parallelism on plates and repairing bowed stock. The honest limit: lapped faces are translucent-matte; optical clarity requires a subsequent polish. Both belong on the drawing before quoting, not after.
One material, many routes: on Alkali-Free Glass we also quote edge grinding, drilling, grinding, double-side polishing, and multi-step drawings are the norm rather than the exception.
Specification advice
Three items decide most of the cost and lead time on this work:
- Material note: thin sheets below 0.3 mm demand carrier-supported handling through every step.
- Process boundary: lapped faces are translucent-matte; optical clarity requires a subsequent polish.
- Over-specification is the quiet budget killer: a 20/10 scratch-dig face costs roughly three times an 80/50 face, so grade each surface individually.
For the complete framework, see the tolerance design guide and the holes and edges design guide.
Typical applications
Orders for lapping alkali-free glass cluster in oled packaging (cover lids, frit-seal frames, fill-port plates); industrial displays (touch covers, gauge windows, printed bezels); mems devices (cap wafers, TGV substrates, motion-sensor lids). Background reading on the underlying material science: SCHOTT AF 32 eco.
The fastest route to a quote is geometry: use the 3D configurator below, or the site-wide custom glass machining 3D builder for fully custom parts.
Engineers scoping this work usually also review alkali-free display glass, alkali-free glass wafers, ITO coated glass.
Frequently asked questions
What tolerances are achievable on Alkali-Free Glass parts?
Ground features hold +/-0.01 mm and lapped thickness reaches +/-0.003 mm. Thin sheets below 0.3 mm demand carrier-supported handling through every step.
What thickness range do you stock for Alkali-Free Glass?
Standard stock spans 0.10 – 1.1 mm, with blanks up to 400 x 300 mm. Other formats are sourced per order.
How does Alkali-Free Glass behave under heat?
CTE is 3.2 x 10^-6 /K and continuous service reaches 600 C (Tg 717 C), which is what drives its use where no alkali ion migration into TFT or sensor layers matters.
What accuracy does lapping hold?
Flatness 1 – 3 um with minimum features of thickness +/-0.003 mm. Lapped faces are translucent-matte; optical clarity requires a subsequent polish.
What equipment runs the lapping work?
Cast-iron lap plates with boron carbide and alumina slurries.
Specifications on this page were last reviewed by our engineering team in July 2026.