Etching Borofloat 33: Borofloat 33 (CTE 3.25 x 10^-6 /K, 350 nm – 2.0 um); Etching to depth control +/-1 um. Single-piece prototypes to production volumes, quoted from your drawing.
The combination of Borofloat 33 and Etching comes up constantly in RFQs for a reason – the material offers anodic bonding to silicon, and Etching is the right way to get accurate geometry into it. Expect depth control +/-1 um and isotropic smooth walls.
The numbers
| 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 | Etching |
| Working tolerance | depth control +/-1 um |
| Minimum feature | 10 um channel width (masked HF) |
| Surface finish | isotropic smooth walls |
| Thickness window | 0.1 – 5 mm |
| Edge condition | stress-relief etch available |
| RFQ inputs | PDF/DXF/STEP drawing, quantity brackets, surface and edge spec |
Specification advice
Three items decide most of the cost and lead time on this work:
- Material note: float tin side must be tracked when parts see coating or bonding steps.
- Process boundary: isotropic undercut roughly equals depth, so masks are compensated at layout time.
- 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.
Process window
Etching earns its place through microchannels, cavities and frosted textures without mechanical stress. Its boundary condition – isotropic undercut roughly equals depth, so masks are compensated at layout time – is the first thing our DFM review checks.
Beyond this page, Borofloat 33 routinely runs through lapping, sandblasting, laser cutting, drilling in our shop – most real parts combine two or three of these steps.
Who orders this
Orders for etching borofloat 33 cluster in machine vision (camera windows, ring-light diffusers, calibration plates); led packaging (groove covers, phosphor carriers, package windows); optical sensors (sensor windows, filter caps, lens covers). Background reading on the underlying material science: SCHOTT BOROFLOAT product page.
Dimensions still moving? Configure this part live in the 3D builder below, or open the full custom glass machining 3D builder to start from a blank canvas.
For adjacent specifications, see Borofloat 33 selection guide, 4 inch Borofloat wafers, surface quality guide.
Frequently asked 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 etching hold?
Depth control +/-1 um with minimum features of 10 um channel width (masked HF). Isotropic undercut roughly equals depth, so masks are compensated at layout time.
Specifications on this page were last reviewed by our engineering team in July 2026.