Quick answer: Lapping Borofloat 33 covers Borofloat 33 (CTE 3.25 x 10^-6 /K, 350 nm – 2.0 um); Lapping to flatness 1 – 3 um. Prototypes ship in 5-10 working days.
We lap Borofloat 33 daily, in thicknesses from 0.2 – 40 mm. The controlling numbers: flatness 1 – 3 um working tolerance, thickness +/-0.003 mm minimum features, and Ra 0.2 – 0.6 um matte off the machine. Where the drawing asks for more, downstream lapping and polishing take over.
Specifications at a glance
| Material | Borofloat 33 (SCHOTT float production, wafer grade) |
|---|---|
| Thermal expansion (CTE) | 3.25 x 10^-6 /K |
| Service temperature | 450 C continuous |
| Transmission range | 350 nm – 2.0 um |
| Density | 2.23 g/cm3 |
| Knoop hardness | 480 kg/mm2 |
| Refractive index | 1.471 @ 587 nm |
| Stock thickness | 0.70 – 25.4 mm |
| Maximum blank size | 500 x 500 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 Borofloat 33 we also quote sandblasting, grinding, edge grinding, ultrasonic machining, and multi-step drawings are the norm rather than the exception.
DFM notes from the shop floor
The shop-floor rules that matter here:
- Material note: float tin side must be tracked when parts see coating or bonding steps.
- 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.
The full rules live in our tolerance design guide and holes and edges design guide.
Who orders this
Orders for lapping borofloat 33 cluster in microfluidic devices (chips, manifolds, via plates, bonded stacks); led packaging (groove covers, phosphor carriers, package windows); machine vision (camera windows, ring-light diffusers, calibration plates). Background reading on the underlying material science: SCHOTT BOROFLOAT product page.
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.
Related reading on this site: wafer dicing process, Borofloat 33 selection guide, high-temperature quartz windows.
Common questions
What tolerances are achievable on Borofloat 33 parts?
Ground features hold +/-0.01 mm and lapped thickness reaches +/-0.003 mm. Float tin side must be tracked when parts see coating or bonding steps.
What thickness range do you stock for Borofloat 33?
Standard stock spans 0.70 – 25.4 mm, with blanks up to 500 x 500 mm. Other formats are sourced per order.
How does Borofloat 33 behave under heat?
CTE is 3.25 x 10^-6 /K and continuous service reaches 450 C continuous, which is what drives its use where float-glass flatness off the line 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.
Specifications on this page were last reviewed by our engineering team in July 2026.