SURAGUS EddyCus TF inline Online Sheet Resistance and Thin-Film Thickness Metrology System

Overview

The SURAGUS EddyCus TF inline is a high-precision, non-contact metrology system engineered for real-time, in-line monitoring of sheet resistance (R_s) and metallic thin-film thickness during continuous manufacturing processes. Based on calibrated eddy current induction principles, the system measures changes in electromagnetic coupling between a high-frequency sensor coil and conductive layers deposited on non-conductive or semi-conductive substrates—including glass, polymer foils, silicon wafers, and flexible films. Unlike optical or four-point probe methods, eddy current metrology requires no physical contact, eliminates wear-related drift, and operates reliably under varying ambient conditions—including controlled vacuum environments (<90 °C). Its dual-parameter capability—simultaneous R_s and thickness derivation—enables closed-loop process control in roll-to-roll (R2R), sputtering, evaporation, and inkjet-printed electronics lines. The system is not a generic thickness gauge; it is a physics-based resistivity-thickness correlator optimized for conductive thin films where electrical performance directly governs functional behavior.

Key Features

• Real-time, non-contact measurement at up to 1000 Hz sampling rate—enabling sub-millimeter spatial resolution along moving webs or conveyor paths
• Modular sensor architecture supporting single-point validation or multi-zone line-scan configurations (1–99 independent channels)
• Vacuum-rated variants available for integration into PVD/CVD cluster tools, with thermal stability certified up to 90 °C
• Configurable gap distances (5–75 mm) accommodate diverse substrate geometries—from rigid 200 mm wafers to low-tension polymer webs
• Multi-range R_s calibration modes: high-sensitivity (0.0001–10 Ω/□), standard (0.01–1,000 Ω/□), and high-resistivity (10–100,000 Ω/□), each with traceable accuracy specifications
• Simultaneous estimation of metal layer thickness (e.g., Al, Ag, Mo, Ag paste) from R_s and bulk conductivity assumptions—validated against XRF and cross-sectional SEM references
• Industrial-grade I/O suite including UDP/TCP sockets, Modbus RTU/TCP, programmable .NET libraries, and isolated analog/digital triggers for PLC synchronization

Sample Compatibility & Compliance

The EddyCus TF inline is validated for use across a broad spectrum of conductive thin-film systems: sputtered ITO/IZO, evaporated Ag grids, inkjet-printed Ag nanowire networks, CNT/polymer composites, PEDOT:PSS coatings, graphene transfer films, and laser-patterned metal meshes. Substrates include soda-lime glass, borosilicate, PET/PEN foils, quartz, and silicon wafers. All measurements comply with fundamental electromagnetic theory (Lenz’s law and skin-depth modeling) and are traceable to NIST-traceable reference standards. The system architecture supports GLP/GMP-aligned operation: time-stamped raw data streams, user-access logs, electronic signatures, and audit trails—fully compatible with FDA 21 CFR Part 11 when deployed with validated third-party SCADA or MES platforms. It meets mechanical and EMC requirements per EN 61326-1 for industrial measurement equipment.

Software & Data Management

SURAGUS provides the EddyControl software suite as a configurable framework—not a black-box GUI. It delivers raw sensor voltage waveforms, demodulated amplitude/phase outputs, and derived R_s/thickness values via open APIs. Users may implement custom calibration models (e.g., incorporating temperature compensation or multi-layer correction factors) using Python or C# extensions. Data export formats include CSV, HDF5, and memory-mapped binary for integration with MATLAB, Python pandas, or LabVIEW. All measurement sessions are timestamped with microsecond precision and support hardware-triggered acquisition synchronized to encoder pulses or PLC strobes. Optional add-ons include statistical process control (SPC) dashboards with Cp/Cpk calculation, real-time deviation mapping, and alarm thresholds tied to ISO 9001-defined control limits.

Applications

• Architectural smart glass production: monitoring low-emissivity (Low-E) coating uniformity on float glass lines
• Touch sensor manufacturing: verifying Ag grid continuity and R_s homogeneity across 10+ inch panels prior to lamination
• OLED encapsulation: quantifying thin Al or Mg:Ag cathode thickness in inert-gas gloveboxes
• Photovoltaic transparent electrodes: in-line R_s/transmittance trade-off optimization for perovskite top cells
• Flexible heating films: ensuring consistent NiCr or carbon-black ink thickness on PET substrates for automotive defrosting elements
• Fuel cell bipolar plates: validating TiN or stainless-steel coating integrity post-PVD on graphite substrates
• EMI shielding packaging: rapid screening of vapor-deposited Al layers on pharmaceutical blister foils

FAQ

Can the EddyCus TF inline measure non-metallic conductive films like ITO or PEDOT:PSS?
Yes—provided the film exhibits sufficient electrical conductivity (>10⁻³ S/cm) and resides on a non-conductive substrate. Calibration requires reference samples with known R_s measured by accredited four-point probe.

Is vacuum compatibility standard or optional?
Vacuum-rated sensors (KF40 or CF flange options) and feedthrough cabling are available as factory-configured options. Standard units operate in ambient air or dry nitrogen environments.

How is thickness accuracy affected by substrate curvature or surface roughness?
Eddy current response is sensitive to lift-off variation. For curved or textured surfaces, gap distance must be stabilized via mechanical guides or active focus tracking. Surface roughness >10% of skin depth introduces measurable uncertainty and should be characterized separately.

Does the system support automated pass/fail classification based on user-defined R_s tolerances?
Yes—via programmable logic in EddyControl or external PLC integration. Binary output signals (OK/NOK) can drive reject mechanisms or log events to MES databases.

What documentation is provided for regulatory validation?
SURAGUS supplies IQ/OQ templates, sensor calibration certificates (traceable to PTB or NIST), uncertainty budgets per GUM guidelines, and interface protocol specifications—all required for FDA/EU MDR submissions.