1. Start with the Function and Supply Scope

A useful custom ITO glass specification describes what the finished component must do and how it will be accepted. Dimensions and a nominal sheet-resistance value are only part of that definition. Optical performance, current paths, contacts and operating conditions must work together.

State whether the part is a transparent electrode, heater, display cover, optical window or conductive dome. Define the delivery scope: coated glass only, patterned glass, contacts, attached leads or an agreed assembly. Identify mandatory limits and targets open to engineering review.

2. Core Specification Checklist

3. Define the Substrate and Mechanical Drawing

Specify the glass type or approved grade, overall dimensions and thickness. Include contour and thickness tolerances, holes, slots, corner radii, edge finish and any strengthening requirement. For an optical path, define the clear aperture and relevant flatness, wedge or transmitted-wavefront limits.

For domes, include curvature, height, wall thickness, flange geometry and the surfaces used as datums. State whether a model is reference geometry or part of the controlled definition. Resolve discrepancies between drawing, model and artwork before manufacture.

Do not use “standard tolerance” without an agreed reference. Apply tighter tolerances where they support fit or function, and permit practical alternatives elsewhere when appropriate.

4. Identify Faces, Coated Areas and Exclusions

Label the two faces consistently, for example S1 and S2, with a drawing view that establishes orientation. Mark which face carries ITO, whether the coating is continuous or patterned, and whether any other layers are present.

Distinguish overall glass size, coated area, electrical active area and optical clear aperture. Identify edge exclusions, sealing lands, exposed pads and uncoated bonding regions. These regions may overlap, but their boundaries should not be assumed identical.

For artwork, state whether it is viewed from the coated side or through the substrate. Include registration features or datums so a mirrored interpretation cannot become an assembly error.

5. Specify Sheet Resistance with a Measurement Basis

Write the nominal sheet resistance in Ω/□ and its tolerance. State whether the limits apply to every agreed measurement point, a part average or another explicitly defined statistic. Include test temperature, measurement method, map locations and edge exclusions.

If uniformity is important, provide the calculation used to express it. A percentage without a formula or sampling map can be interpreted in different ways. Agree on the method for curved parts or features too small for the intended probe arrangement.

If the target is not yet known, supply the intended function and electrical constraints. Do not force an arbitrary resistance value into the drawing when electrode geometry or power requirements still need review.

6. Specify the Functional Electrical Path

Sheet resistance characterizes the film; resistance between terminals depends on geometry and contacts. For a uniform rectangular film with full-width opposing contacts, R = RₛL/W, with L as electrode spacing and W as the width perpendicular to current flow. More complex paths need suitable analysis or measurement.

Define the test terminals, reference temperature and acceptable path resistance. State whether attached leads and contact resistance are included. For patterned electrodes, also specify continuity and isolation requirements, including the test method and conditions.

Avoid treating an optical inspection of a gap as proof of electrical isolation. Functional tests should correspond to the intended circuit and operating conditions.

7. Write an Unambiguous Optical Requirement

Provide the actual wavelength band or discrete wavelengths, including relevant tolerances. Distinguish minimum transmission at each wavelength from average transmission across a band, and identify any weighting used in an average.

Specify whether the result applies to the finished coated glass, a bonded assembly or another clearly identified configuration. Include angle of incidence, polarization where relevant, test aperture and reference baseline. An uncoated-substrate-normalized result is not automatically the transmission of the finished part.

For displays, define haze, reflection or appearance criteria where needed. For imaging, include the appropriate scatter, distortion or wavefront requirement. Visible clarity alone does not establish transmission at a near-infrared sensor wavelength.

8. Define Patterns, Busbars and Leads

Provide dimensioned electrode artwork with track widths, gaps, pad sizes, tolerances and alignment datums. State the required electrical connections and isolated regions. Identify which files control nominal geometry and which document controls tolerances.

For busbars and leads, specify placement, connection method, exit direction, length, insulation and strain-relief scope. Confirm compatibility with later bonding, soldering or clamping. Contact materials and attachment details can affect resistance and environmental durability.

Specify whether proposed alternatives require approval. Do not leave the connection method implicit when terminal resistance or heater uniformity is critical.

9. Add Heater Requirements When Heating Is the Function

Supply the voltage range, current or power limit, control mode and intended sensor arrangement. Define target temperature, maximum permitted temperature, warm-up time and the region used to evaluate uniformity.

Describe mounting, ambient temperature, airflow, orientation and contact with liquids or other materials. Electrical power follows the resistance and supply conditions; the achieved temperature also depends on heat transfer. A 24 V input alone does not define a heater.

For anti-fogging, specify humidity, the face that must remain clear and whether the goal is prevention or clearing existing condensation. For de-icing, provide the ice condition and clearance-time requirement as a separate load case.

10. Document Processing and Environmental Exposure

List assembly temperatures, hold times, atmosphere, cleaning chemicals, adhesive contact and other relevant processing steps. Separate manufacturing exposure from continuous service conditions. Include storage conditions if they affect the supplied surfaces or packaging.

For liquid-contact or electrochemical electrodes, identify the solution, temperature, duration and electrical conditions. Compatibility should be evaluated for the actual experiment or device.

If a standard or certification is required, identify the exact document, revision, applicable tests and required evidence. For medical-equipment projects, define component-specific requirements rather than relying on the phrase “medical grade.”

11. Set Inspection, Sampling and Acceptance Criteria

Tie each critical requirement to a measurement method and pass/fail limit. Identify whether inspection is performed on every part, a defined sample or a witness coupon. Agree on how witness measurements represent the finished component.

Specify required reports: dimensions, resistance maps, terminal measurements, spectra or thermal tests as appropriate. If calibration, measurement uncertainty or third-party testing matters, include it in the agreed inspection plan.

For exposure tests, define both the treatment and the allowed post-test change. “Pass thermal cycling” is incomplete without cycle conditions and the optical, electrical and mechanical criteria that must remain satisfied.

12. Plan Prototype Approval, Packaging and Repeat Orders

Use paid prototypes to confirm the important interfaces and functional requirements before releasing production. Record any approved deviations and update the controlled specification after evaluation. A successful sample should correspond to an identifiable drawing and process configuration.

Define protective packaging for the glass, coated surface, edges and contacts. Require coated-face identification where needed for assembly and agree on suitable handling instructions. Specify whether reports and labels must reference the part number, revision and lot.

Separate prototype quantity from production quantity and expected repeat demand. Include destination and required timing for quotation. Minimum order quantity, tooling, pricing and lead time should be confirmed for the approved scope.

13. Copy-and-Complete RFQ Template

Complete the fields relevant to your project. Mark unused fields “not applicable” and unresolved fields “to be agreed”; an empty field should not silently become an assumed acceptance criterion.

CUSTOM ITO GLASS RFQ
Company / contact:
Part number / drawing revision:
Application and function:
Supply scope (glass / pattern / busbars / leads / assembly):
Substrate grade and permitted alternatives:
Outline / thickness / tolerances / edge finish:
Coated face and viewing direction:
Coating coverage / exclusions / clear aperture:
Sheet resistance target and tolerance:
Resistance test method / temperature / map:
Terminal or track resistance and test points:
Pattern artwork / datums / isolation requirements:
Optical band / transmission limits / averaging method:
Optical angle / reference / aperture / haze or image criteria:
Contact layout / lead and attachment requirements:
Supply voltage range / current or power limit, if heating:
Temperature target / warm-up / uniformity / maximum:
Mounting / ambient / airflow / humidity:
Processing / cleaning / liquid contact / exposure:
Inspection / sampling / reports / post-exposure limits:
Prototype quantity / production quantity / repeat demand:
Packaging / delivery destination / required date:
Mandatory requirements / negotiable targets / open questions:
Attachments and controlling document hierarchy:

This is a request template, not a released product specification. Numerical limits and supply scope become binding project requirements only after they are reviewed and agreed.

14. Frequently Asked Questions

15. Send Your Custom ITO Glass Specification for Review

Felix Glass supports reviews of custom ITO windows, domes, patterned electrodes, laboratory slides and heater glass. Send your completed checklist with the drawing, artwork and quantities so the optical, electrical and manufacturing requirements can be evaluated together.

Dongguan Felix Glass Co., Ltd.
Email: james@felixglass.com
Phone: +86-18565032888