IEC 60068-2-42:2003

Overview

IEC 60068-2-42:2003 is an international standard developed by the International Electrotechnical Commission (IEC) outlining a specific environmental test method-Test Kc-for assessing the corrosive effects of atmospheres polluted with sulphur dioxide (SO₂) on electrical contacts and connections. This standard provides an accelerated testing procedure to evaluate how sulphur dioxide contamination influences the performance and reliability of precious metal contacts and solderless connections.

Sulphur dioxide is a common atmospheric pollutant that can lead to corrosion, impacting the electrical resistance and durability of connectors. IEC 60068-2-42 focuses on this particular pollutant's effects, enabling manufacturers and testers to conduct comparative corrosion assessments under controlled conditions. However, it is important to note that this test is not designed as a general corrosion test for all industrial atmospheres.

Key Topics

• Purpose and Scope
  The test specifically targets the influence of sulphur dioxide on contacts made of precious metals or precious metal coatings (excluding silver and some silver alloys). It is primarily intended to detect changes in contact resistance resulting from exposure to sulphur dioxide atmospheres, with a focus on solderless connections' tightness and effectiveness.

• Test Atmosphere Composition

  • Sulphur dioxide concentration: 25 ± 5 ppm by volume (total SOₓ expressed as SO₂)
  • Temperature: maintained at 25 °C ± 2 °C
  • Relative humidity: controlled between 70% and 80%, optimally around 75%

• Test Setup and Chamber Requirements
  The test chamber must be constructed of materials inert to sulphur dioxide and designed to allow safe airflow, with 3 to 5 complete atmosphere exchanges per hour. Specimens are protected from direct gas flow and subjected to either relative movement through the atmosphere or slight agitation to simulate realistic environmental conditions.

• Performance Criteria
  The major assessment criterion is the variation in contact resistance caused by exposure to the sulphur dioxide atmosphere, measured using standard electrical test methods such as IEC 60512-2-1.

• Preconditioning and Handling
  Specimens are not cleaned before testing unless otherwise specified in manufacturer instructions to ensure real-world contamination effects are considered.

Applications

• Connector and Electronics Component Testing
  IEC 60068-2-42 is widely used for qualification and quality assurance testing of connectors, switches, and other electromechanical components intended for environments where sulphur dioxide pollution is a concern (e.g., industrial sites, urban areas).

• Material Selection and Design Verification
  Manufacturers use the test to compare different materials and coatings for corrosion resistance, enabling optimization of contact materials to enhance longevity and reliability.

• Solderless Connection Evaluation
  The test verifies the sealing and integrity of solderless connections, ensuring that such connections maintain low contact resistance and remain resistant to sulphur dioxide induced corrosion.

• Compliance and Standardization
  The standard is a reference point for companies aiming to meet international quality benchmarks in electromechanical system performance under corrosive conditions.

Related Standards

• IEC 60068-2-49 - Provides guidance on corrosion testing methods complementing accelerated tests like Test Kc, essential for interpreting results in the context of broader environmental exposure.

• IEC 60355 - Offers additional reference material related to corrosion effects on electronic components.

• IEC 60512-2-1 - Defines electrical tests for connectors, including methods to measure contact resistance critical to evaluating performance in sulphur dioxide environments.

Practical Value

Implementing IEC 60068-2-42 testing allows organizations to:

• Detect potential corrosion vulnerabilities early in the product development cycle.
• Enhance product durability by selecting corrosion-resistant materials and finishes.
• Ensure reliable electrical connectivity in sulphur dioxide-polluted atmospheres, reducing failure risks.
• Facilitate conformity with international testing protocols, supporting global market access.
• Improve safety and performance consistency in sectors such as telecommunications, automotive electronics, and industrial control systems.

By adopting IEC 60068-2-42, manufacturers and quality engineers gain a practical, standardized method to evaluate sulphur dioxide corrosion-an important factor in electrical contact performance for many real-world applications.