Technical Insight
Static-Decay and Charge-Generation Testing Under Controlled Humidity
A controlled-humidity test plan that separates charge generation from charge dissipation and keeps the electrification method, specimen, ground path, timing, and environmental history attached to every result.
Author: Aurexene Materials Engineering Team · Last updated: 2026-08-28
Quick Answer
Test charge generation and static decay as separate functions, then measure the relevant surface, bulk, or ground path on the same conditioned specimen. Use a registered dry-humid-dry sequence so reversible humidity response can be separated from history, damage, and fixture artifacts.
Problem
A surface-resistance result cannot tell how much charge a material pair creates during contact or motion. It also cannot by itself establish how an imposed charge decays through a part, coating, film, interface, or installed ground.
Humidity can change the specimen surface, bulk, contamination, contacts, fixture, and ground path at the same time. Without fixed conditioning, timing, and recovery, a result may describe the test history rather than the ESD system.
Mechanism
Charge generation is controlled by the contacting materials, surface state, contact area and force, motion, separation, cycle history, and effective capacitance. Static decay begins from an imposed charge and follows whatever surface, bulk, interface, and ground paths are available.
A humidity response is not a unique material diagnosis. Adsorbed moisture, host uptake, ionic residue, coating defects, contact changes, and fixture leakage can produce similar shifts. A return toward the initial dry response supports reversibility; incomplete recovery triggers material, interface, contamination, and fixture review.
Tradeoff
A tightly controlled coupon isolates variables but may omit the geometry, seams, fasteners, handling, protective layers, or ground path that control the installed result. A full assembly is representative but requires segment measurements to locate a failure.
Stronger or more repeatable laboratory charging is not automatically more representative. The charging route should reproduce the intended contact, motion, and counter-material closely enough to support the decision.
Material Strategy
For compounds and coatings, screen Conductive Carbon Black, Antimony Tin Oxide (ATO), Multi-Walled Carbon Nanotubes (MWCNT), Few-Walled Carbon Nanotubes (FWCNT), or Single-Walled Carbon Nanotubes (SWCNT) only in the intended host, loading, dispersion, thickness, and process state.
For films or layered systems using SWCNT-nano-Ag or MXene, retain the substrate, junctions, protective layer, contacts, and ground construction. Powder or film identity alone does not establish charge behavior.
Recommended Architectures
| Test route | Use when | Controls that must travel with the result |
|---|---|---|
| Charge-generation screen | Contact, separation, rubbing, conveying, or handling creates the relevant static event. | Material pair, surface state, contact force and area, motion, speed, cycles, geometry, initial state, temperature, and humidity |
| Static-decay screen | The decision concerns removal of an imposed charge from a coupon, part, film, or assembly. | Charging method, initial level, endpoint, time resolution, capacitance or load, geometry, isolation or ground path, and environment |
| Dry-humid-dry qualification | Environmental sensitivity or recovery determines acceptance. | Conditioning duration, equilibrium check, measurement order, fixture blanks, recovery time, repeat specimens, and matched electrical-path data |
Measurement & Validation
- Define the charging event and counter-material from the use case; do not leave operator rubbing or handling uncontrolled.
- Precondition specimens and fixture, record temperature and humidity, and verify the instrument baseline and ground state.
- Measure charge generation, static decay, and the selected surface, volume, or resistance-to-ground path without changing specimen state unnecessarily.
- Repeat at the humid condition and after a documented return-to-dry recovery. Include blanks, repeats, spatial locations, and a reference construction.
- Compare distributions and recovery, not only one average or one pass/fail point. Investigate fixture leakage and contact drift before assigning a material mechanism.
Qualification Boundary
Record the material pair, charging and decay methods, initial and endpoint definitions, specimen and assembly geometry, effective capacitance or load, ground state, electrodes, voltage and timing for path measurements, conditioning setpoints and duration, recovery, instrument range, repeat count, location, and uncertainty. Set acceptance limits from the intended use and approved method; this page does not supply them.
Related Products
Related Applications
Related Comparisons
No reviewed comparison page is available yet. Candidate comparisons must use the same material pair, charging event, specimen, ground state, conditioning sequence, and endpoint definitions.
Downloads & Engineering Support
The brochure is approval-required application context, not an ESD test standard or a source of product-specific charge and decay values.
- Request ESD validation support
- Discuss controlled conditioning and test design
- Discuss production sampling and release controls
What to Validate
The functional distinctions and reporting controls are engineering guidance. No product from Aurexene Materials is assigned a charge-generation level, static-decay time, resistance class, or humidity dependence until verified evidence is available for the named grade, host, construction, method, and conditions.
Need to apply this boundary to a grade, formulation, test method, or production route? Discuss it with the Aurexene Materials Engineering Team.