IEC 62899-202-8:2024

Overview

IEC 62899-202-8:2024 is an IEC international standard in the Printed Electronics series that specifies a method to measure the difference in electrical resistance with respect to printing direction for conductive films made from wire-shaped (high aspect‑ratio) conducting materials. It covers solution-processed conductive films fabricated by coating and printing processes and is intended to quantify resistance anisotropy that arises from alignment of wire-shaped materials (e.g., metal nanowires) during printing.

Key topics and technical requirements

• Scope: Measurement of resistance difference by printing direction for wire-shaped/wire-type conductive materials in printed conductive films.
• Measurement environment: Tests are carried out at 23 °C ± 1 °C and relative humidity 50 % ± 5 %, with atmospheric pressure per ISO 291.
• Measurement method: Four‑wire (Kelvin) resistance measurement is required to minimise lead/contact errors.
• Resistance ranges and applied currents: The standard references resistance ranges mapped to test currents (examples include 1 A for <20 mΩ, 100 mA for <200 mΩ, down to 1 µA for higher resistances) as given in the document’s test table.
• Sample preparation and geometry: Rectangular samples with a length‑to‑width ratio ≥ 30 are specified to reduce line interference. A recommended size is 300 mm × 10 mm with tolerances of ±0.2 mm. Samples can be prepared at angles 0°–180° relative to the machine direction (MD) to evaluate anisotropy between MD and cross direction (CD).
• Apparatus and fixturing: Samples are mounted on a rigid plate and connected to measuring equipment using conductive wires or conductive paste; illustrations and holder settings are provided for reproducible four‑wire contacts.
• Reporting: The standard defines how to report resistance values and anisotropy results for comparison between printing directions.

Applications and users

Practical uses for IEC 62899-202-8 include:

• Quality control and process optimization for printed electronics manufacturers producing flexible electrodes, interconnects, and metal‑based transparent conductive (TC) films.
• Ink and material formulators assessing how ink composition and wire alignment affect electrical performance.
• R&D labs evaluating printing equipment, coating processes, or post‑treatments that influence anisotropic conductivity.
• Device integrators (e.g., displays, touch panels, appliance keypads, flexible sensors) who need consistent directional conductivity.

The standard helps quantify directional resistance differences that can impact device performance, yield and reliability.

Related standards

• IEC 62899-201 - Printed electronics: Materials - Substrates
• IEC 62899-202 - Printed electronics: Materials - Conductive ink
• ISO 291 - Plastics: Standard atmospheres for conditioning and testing

Keywords: IEC 62899-202-8, printed electronics, conductive ink, conductive film, resistance anisotropy, printing direction, four-wire measurement, wire-shaped materials, metal nanowires.