CASE STUDY · Precision Lapping and Polishing

Double-Sided Polished Glass Processing Case Study

Around thickness, parallelism, flatness and two-sided appearance, we build a continuous flow from material cutting to double-sided polishing, cleaning and inspection.

Double-sided polished glass processing workshop

Double-sided polished glass inspection and delivery

Project Overview

The complete route from material confirmation to finished-part delivery

Double-sided polished glass is often used for optical windows, precision substrates and functional carriers. Processing must consider material removal, thickness uniformity, parallelism of the two faces, edge protection and the cleaning method together, avoiding focus on a single surface at the expense of overall geometry.

Typical materials: Fused quartz, borosilicate glass, alkali-free glass and others
Main operations: Cutting to size, lapping, double-sided polishing, cleaning, inspection
Control focus: Thickness, parallelism, flatness, scratches and digs
Applications: Optical windows, precision substrates, sensing and electronic components

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ENGINEERING GUIDE

Design geometry and two-sided surface quality together

Double-sided polishing is not simply making both faces bright; it establishes thickness, TTV, parallelism, form and two-sided surface quality while controlling material removal. Lapping first establishes the geometry, then polishing reduces roughness and removes damage from earlier operations.

Applications

Where it can be used

Optical windows, protective windows, filters and coated substrates
Substrates for MEMS, sensors, microfluidics and wafer-level packaging
Substrates for displays, thin films, optoelectronics and microelectronics
Precision spacers, transparent carrier plates and laboratory equipment windows
Parallel plates in laser, imaging and analytical instruments

Material Selection Logic

Why glass

When both faces take part in the optical path, bonding, coating, lamination or precision positioning, a pristine or lapped surface often cannot meet the roughness, cleanliness and geometry requirements. Double-sided polishing reduces scatter and interface defects and makes thickness and the relationship between the two faces more controllable.

Material Selection

Common materials and their applications

Material	Applications	Selection focus
BOROFLOAT® 33	General precision substrates, windows and thermally stable structures	Typical finished thickness range 0.10-3.00 mm
Fused quartz / JGS1	Low CTE, UV/laser and precision optics	Confirm the quartz grade, band and subsurface damage
EAGLE XG® / alkali-free glass	Thin-film, display, electronic and low-alkali substrates	Avoid unnecessarily disturbing the high-quality pristine surface
PYREX® Micro-Electro	MEMS, glass-silicon bonding and wafer-level packaging	Focus on controlling TTV, warp, edges and cleanliness

Typical Parameters

Common enquiry parameters

Item	Common starting points or wording	Engineering notes
Finished thickness	BF33 typically 0.10-3.00 mm	Other materials and greater thicknesses are evaluated to drawing
Thickness tolerance	Precision parts are generally discussed from ±0.02 mm; micron level can be evaluated	BF33 can be evaluated to ±5 μm, subject to confirmation with size
TTV	General precision substrates are commonly discussed from ≤10-25 μm; high precision can be evaluated to ≤1-5 μm	BF33 can be evaluated to <2 μm; PYREX® wafers can be evaluated to ≤1 μm
Flatness	Defined in μm, interference fringes or wavelength units	State the clear aperture, test wavelength and support method
Roughness	Precision-polished surfaces are commonly discussed from Ra 1-2 nm	State the instrument, scan length and filter conditions
Scratch/Dig	60/40 as standard; 40/20 or 20/10 can be evaluated for higher requirements	State the standard applied and the effective area

Structure and Function

What it usually needs to look like

Commonly rectangular substrates, discs/wafers, square windows, round windows, narrow strips, ring parts or parallel plates with holes and slots. Both faces can share the same grade, or face A can be a high-grade functional face and face B a standard polished face.

Provide a low-scatter transparent interface for two-sided optical paths
Provide controlled surfaces for bonding, lamination and coating
Establish thickness, TTV, parallelism and form
Provide a stable geometric reference for precision assembly

Performance Requirements

Performance items recommended for confirmation

Low TTV and a stable parallel relationship
Flatness and warp meeting lamination, coating or optical requirements
Low roughness, low scratches and digs, and controlled subsurface damage
A continuous chamfer with no through cracks and no excessive intrusion into the functional area
Low particles, low residue and no visible water marks or fingerprints after cleaning

Preparing Your Enquiry

Please provide in the drawing or enquiry

Material grade, outline dimensions, initial and finished thickness, thickness tolerance, TTV, parallelism/wedge angle, flatness, surface grade of both faces, clear aperture, edges, subsequent processes, quantity and inspection standard.

The parameters above are for preliminary material and process selection and do not constitute a uniform guarantee for all dimensions, thicknesses and materials. Final specifications, measurement methods and delivery standards are governed by the drawing, samples and order documents confirmed by both parties.

Material and blank preparation

Confirm material grade, initial thickness, dimensions, processing allowance and effective area, and set up batch identification.

Double-sided polished glass processing and material preparation

Double-sided polished glass processing inspection

Lapping establishes geometry

Staged lapping controls thickness and the relationship between the two faces while leaving a uniform allowance for fine polishing.

Double-sided precision polishing

The polishing cycle is set by surface grade and geometric requirements, with thickness variation and surface defects continuously controlled.

Cleaning and optical appearance inspection

Remove polishing residue, check two-sided appearance, edges and critical dimensions, and package with separation as required.

Start material selection and processing requirements from the same drawing

Send the drawing and key acceptance items and we will assess the project together with the material and process route.

Email Your Drawings Contact the Engineering Team