Alternating humidity and temperature test

Alternating Humidity and Temperature Testing Service – Accredited ISO/IEC 17025 Environmental Durability and Reliability Assessment for the Croatian Market

Alternating humidity and temperature testing is a critical environmental evaluation method used to assess the resistance of materials, components, and products to the combined effects of cyclic temperature changes and moisture variations. This test simulates the real-world conditions that products encounter in tropical, coastal, and seasonal climates, where daily or seasonal changes in temperature and humidity can cause condensation, corrosion, delamination, loss of adhesion, electrical failure, and mechanical degradation. The alternating humidity and temperature test is essential for a wide range of industries, including automotive, electronics, aerospace, construction, medical devices, packaging, and consumer goods, where products must maintain their performance and integrity under fluctuating environmental conditions. In the Croatian market, where the Hrvatski zavod za norme (HZN), the Ministarstvo gospodarstva i održivog razvoja, the Državni inspektorat, the Ministarstvo graditeljstva i prostornoga uređenja, and the Carinska uprava enforce strict quality, safety, and environmental standards aligned with EU directives and HRN EN (Croatian standards based on European norms), the accurate evaluation of alternating humidity and temperature resistance is essential for product certification, supplier qualification, type testing, quality control in manufacturing, and import-export processes. Our laboratory offers a comprehensive alternating humidity and temperature testing service, applying standardized methods such as IEC 60068-2-30 (Damp heat, cyclic), IEC 60068-2-38 (Composite temperature/humidity cyclic test), ASTM D2247, ISO 6270-2, HRN EN 60068-2-30, and HRN EN 60068-2-38 to simulate real-world environmental stress cycles and evaluate the performance of products under controlled conditions of alternating temperature and humidity. All tests are performed under our ISO/IEC 17025 (CNAS) accreditation, and the resulting reports are fully accepted by Croatian authorities and notified bodies, making them indispensable for regulatory compliance, product validation, and market access in Croatia and the European Union.

Test Samples and Materials We Regularly Examine

Our laboratory receives a wide variety of materials, components, and products for alternating humidity and temperature testing. Typical samples include:

• Electronic components and assemblies – PCBs, connectors, sensors, displays, power supplies, and electronic modules for automotive, industrial, and consumer applications.
• Automotive and transportation components – interior trim, lighting systems, sensors, control units, wiring harnesses, and door seals.
• Building and construction materials – insulation materials, sealants, adhesives, wall coverings, floorings, roofing membranes, and window frames.
• Coatings and paints – organic coatings, powder coatings, electroplated coatings, and surface treatments for corrosion protection.
• Medical devices and pharmaceutical packaging – drug-delivery devices, diagnostic equipment, and packaging materials that must maintain sterility and integrity.
• Consumer goods and appliances – household appliances, power tools, and electronics that may be exposed to humid and temperature-variable conditions.
• Packaging materials – flexible packaging, rigid containers, and barrier films for food and pharmaceutical products.
• Prototype and new product designs – submitted by manufacturers for validation of alternating humidity and temperature resistance before series production.
• Field-retrieved components – for failure analysis and remaining life assessment.

Cyclic Damp Heat Test (IEC 60068-2-30) – Simulating Condensation and Temperature Cycling

The cyclic damp heat test subjects the specimen to repeated 24‑hour cycles of high humidity and temperature variation, which typically include a period of high humidity and condensation, followed by a period of drying and lower temperature. This test is more severe than the steady‑state damp heat test and better simulates the conditions of real‑world use, where condensation and temperature changes occur daily.

• Cyclic damp heat test (IEC 60068‑2‑30 / HRN EN 60068‑2‑30 / NTC 5600 – for the condensation and cycling effects) – we place the test specimen in a temperature‑ and humidity‑controlled chamber and subject it to a cyclic profile: typically, the temperature is raised to 55 °C at 95 % RH, held for 12 hours, then reduced to 25 °C at 95 % RH, and held for 12 hours. The number of cycles is typically 6, 12, or 24 cycles (corresponding to 6, 12, or 24 days). The specimen is inspected for corrosion, blistering, and electrical failure after the cycles. We report the number of cycles, the visual condition, and the electrical performance (pass/fail).
• Cyclic damp heat test with functional monitoring (NTC 5601 – for the in‑situ performance evaluation) – during the cyclic damp heat test, we monitor the electrical performance of the specimen (e.g., the resistance, the insulation, and the signal integrity) in real time. The test is stopped if a functional failure occurs. We report the time to failure (in cycles) and the failure mode.
• Cyclic damp heat test with condensation measurement (NTC 5602 – for the water film formation) – we place a condensation sensor (or a test plate) next to the specimen to monitor the formation of a water film on the surface. The presence and the duration of the condensation are recorded. We report the condensation pattern and the effect on the specimen.
• Cyclic damp heat test for automotive components (ISO 16750‑4 / NTC 5603 – for the climate‑chamber testing) – we perform the cyclic damp heat test according to the automotive standard (e.g., ISO 16750‑4) which uses a temperature‑humidity profile that simulates the conditions in the passenger compartment and the engine compartment. We report the performance and the compliance with the automotive standard.
• Cyclic damp heat test with electrical load (NTC 5604 – for the combined environmental and electrical stress) – we apply an electrical load (e.g., a supply voltage or a signal) to the specimen during the cyclic damp heat test, to simulate the real‑world operating conditions. The test is used to detect any failure due to the combined stress. We report the performance and the failure mode.

Composite Temperature/Humidity Cyclic Test (IEC 60068‑2‑38) – Simulating Complex Environmental Profiles

The composite temperature/humidity cyclic test uses a more complex profile that includes multiple temperature and humidity steps within a single cycle, simulating a wider range of environmental conditions, including cold, hot, and humid phases. This test is used for more demanding applications, such as aerospace and military equipment.

• Composite temperature/humidity cyclic test (IEC 60068‑2‑38 / HRN EN 60068‑2‑38 / NTC 5610 – for the complex environmental simulation) – we subject the test specimen to a composite profile that typically includes a temperature cycle from -10 °C to +65 °C, with humidity steps at 93 % RH and 25 °C. The profile is repeated for a specified number of cycles (e.g., 10 cycles). The specimen is inspected for mechanical and electrical degradation. We report the number of cycles, the visual condition, and the electrical performance (pass/fail).
• Composite test with functional monitoring (NTC 5611 – for the real‑time performance evaluation) – we monitor the electrical and mechanical performance of the specimen during the composite test. The test is stopped if a functional failure occurs. We report the time to failure (in cycles) and the failure mode.
• Composite test with humidity and temperature ramps (NTC 5612 – for the controlled rate of change) – we control the rate of temperature and humidity change during the composite test (e.g., 1 °C/min, 2 °C/min) to simulate the thermal shock and the condensation effects. We report the ramp rates and the effect on the specimen.
• Composite test for electronic and aerospace components (NTC 5613 – for the high‑reliability applications) – we perform the composite test according to the requirements of the aerospace and defense standards (e.g., MIL‑STD‑810G) which use a specific composite profile. We report the performance and the compliance with the standard.
• Composite test with electrical load and vibration (NTC 5614 – for the combined environmental and mechanical stress) – we apply an electrical load and a mechanical vibration to the specimen during the composite test, to simulate the real‑world operating conditions in vehicles and aircraft. We report the performance and the failure mode.

Temperature and Humidity Cycling with Condensation – Evaluating the Resistance to Moisture Ingress

Condensation is a major cause of corrosion, electrical leakage, and the degradation of adhesives and coatings. Our tests specifically evaluate the resistance of materials and components to the condensation that occurs during temperature and humidity cycling.

• Condensation test (ASTM D2247 / ISO 6270‑2 / NTC 5620 – for the moisture resistance evaluation) – we place the test specimen in a condensing humidity chamber at 40 °C and 100 % RH (with continuous condensation) for a specified duration (e.g., 240, 500, or 1000 hours). The specimen is inspected for blistering, corrosion, and loss of adhesion. We report the blistering rating (ASTM D714), the corrosion rating (ASTM D610), and the adhesion rating (ASTM D3359).
• Condensation test with temperature cycling (NTC 5621 – for the cyclic condensation) – we subject the specimen to repeated cycles of condensation (at 40 °C, 100 % RH) and drying (at 23 °C, 50 % RH) for a specified number of cycles. This simulates the daily condensation‑drying cycle. We report the number of cycles and the condition of the specimen.
• Condensation test with electrical bias (NTC 5622 – for the electrochemical migration test) – we apply a voltage bias (e.g., 5 V, 12 V) to the test specimen during the condensation test to evaluate the susceptibility to electrochemical migration (dendrite growth) between adjacent conductors. We report the occurrence of dendrites and the leakage current.
• Condensation test for coatings and paints (NTC 5623 – for the moisture resistance of coatings) – we expose coated panels to a condensing humidity environment (40 °C, 100 % RH) for a specified duration (e.g., 240, 500, or 1000 hours). The panels are inspected for blistering, loss of adhesion, and corrosion. We report the blistering rating, the adhesion rating, and the corrosion rating.
• Water absorption and dimensional change measurement (NTC 5624 – for the moisture uptake) – we measure the water absorption (in %) and the dimensional change (in %) of the specimen after the condensation test. The water absorption is correlated with the degradation. We report the water absorption, the dimensional change, and the effect on the properties.

Environmental and Aging Effects – Evaluating Long‑Term Durability

To fully understand the long‑term performance of the product under alternating humidity and temperature conditions, we perform environmental and aging tests that simulate the cumulative effect of repeated cycles and the material degradation over time.

• Long‑term cyclic humidity and temperature test (NTC 5630 – for the accelerated aging) – we subject the specimen to a large number of alternating humidity and temperature cycles (e.g., 100 cycles, 200 cycles) to accelerate the aging process. The specimen is inspected for degradation and functional performance at regular intervals. We report the number of cycles, the degradation progression, and the predicted service life.
• Combined alternating humidity and temperature with UV exposure (NTC 5631 – for the outdoor applications) – we combine the alternating humidity and temperature test with UV radiation (UVA‑340) to simulate the outdoor environment. The specimen is exposed to UV radiation during the light phase of the cycle. We report the combined‑stress performance and the degradation.
• Combined alternating humidity and temperature with salt spray (NTC 5632 – for the coastal applications) – we combine the alternating humidity and temperature test with a salt spray (5 % NaCl) to simulate the coastal and marine environments. The specimen is exposed to salt spray during the wet phase of the cycle. We report the corrosion rating and the condition of the specimen.
• Combined alternating humidity and temperature with mechanical stress (NTC 5633 – for the stress‑corrosion evaluation) – we apply a mechanical stress (e.g., a tensile or a bending load) to the specimen during the alternating humidity and temperature test, to evaluate the susceptibility to stress corrosion cracking (SCC) and environmentally assisted cracking. We report the time to failure and the failure mode.
• Combined alternating humidity and temperature with electrical load (NTC 5634 – for the operational reliability) – we apply an electrical load to the specimen during the alternating humidity and temperature test, to simulate the real‑world operating conditions. The test is used to detect any failure due to the combined environmental and electrical stress. We report the performance and the failure mode.

Performance Monitoring and Failure Analysis – Evaluating the Degradation Mechanisms

To fully understand the degradation mechanisms and to identify the root cause of any failure, we perform a comprehensive performance monitoring and failure analysis during and after the alternating humidity and temperature tests. These analyses are essential for design improvement and for certification by the HZN and other Croatian authorities.

• Continuous electrical monitoring (NTC 5640 – for the detection of electrical failures) – we continuously monitor the electrical parameters (e.g., the resistance, the insulation resistance, the leakage current, and the capacitance) of the test specimen during the alternating humidity and temperature tests. An abrupt change in the electrical parameters indicates a failure (e.g., a short circuit, a corrosion‑induced open circuit, or a change in the dielectric properties). We report the electrical parameter evolution and the time of failure.
• Periodic functional verification (NTC 5641 – for the functional integrity check) – at regular intervals during the test, we remove the specimen from the chamber and perform a full functional verification (e.g., a performance test, a calibration check, or a safety test). The functional test results are compared with the pre‑test results. We report the functional degradation and the pass/fail status.
• Visual and microscopic inspection (NTC 5642 – for the detection of surface damage) – we inspect the specimen surface for signs of corrosion, blistering, cracking, or delamination using an optical microscope and a scanning electron microscope (SEM). The nature and the extent of the damage are recorded. We report the visual condition and the SEM images.
• Cross‑section analysis (NTC 5643 – for the depth of degradation) – we prepare a cross‑section of the specimen (or the component) and examine it under an optical microscope or a SEM to measure the depth of the corrosion, the diffusion of moisture, or the thickness of the degraded layer. The depth of degradation is reported.
• Chemical analysis of the degradation products (FTIR, XRF – NTC 5644 – for the identification of the corrosion products) – we use Fourier‑transform infrared spectroscopy (FTIR) and X‑ray fluorescence (XRF) to identify the chemical composition of the corrosion products, the degradation products, and the migrated species. The identification helps to understand the degradation mechanism. We report the chemical composition and the degradation mechanism.

Compliance with Environmental and Product Standards – Pass/Fail Criteria

The measured alternating humidity and temperature resistance is compared with the requirements of the relevant product standards and the environmental specifications to determine the conformity of the product. Our tests provide a clear pass/fail result and a statement of compliance with the applicable standards, including the HRN EN standards and the EU directives.

• Compliance with IEC 60068‑2‑30 (NTC 5650 – for the cyclic damp heat test) – we compare the specimen's performance after the cyclic test with the acceptance criteria (e.g., the absence of corrosion, the absence of delamination, and the retention of electrical performance). We report the compliance and the pass/fail status.
• Compliance with IEC 60068‑2‑38 (NTC 5651 – for the composite temperature/humidity cyclic test) – we compare the specimen's performance after the composite test with the acceptance criteria. We report the compliance and the pass/fail status.
• Compliance with automotive standards (ISO 16750‑4 / NTC 5652 – for the climate testing) – we perform the alternating humidity and temperature tests according to the automotive environmental standard ISO 16750‑4, and we compare the results with the specified requirements. We report the compliance and the pass/fail status.
• Guarantee verification (NTC 5653 – for the contractual purposes) – we test the product to verify that its alternating humidity and temperature resistance is within the guaranteed values specified in the purchase order or the design specification. We report the measured performance and the margin relative to the guarantee.
• Environmental compliance for the Croatian market (NTC 5654 – for the EU and Croatian regulations) – we verify that the product meets the environmental durability requirements of the Croatian regulations (based on the HRN EN standards) and the EU directives. The statement of compliance is included in the test report. We report the compliance and the applicable regulations.

Complementary Tests – Material Characterization and Physical Property Evaluation

To provide a comprehensive assessment of the alternating humidity and temperature resistance and to correlate it with the material properties, we perform complementary tests, including material characterization and physical property evaluation.

• Water absorption measurement (ASTM D570 / NTC 5660 – for the moisture uptake) – we measure the water absorption (in %) of the material after the alternating humidity and temperature exposure, by weighing the specimen before and after the exposure. The water absorption is correlated with the degradation. We report the water absorption and the effect on the properties.
• Dimensional stability measurement (NTC 5661 – for the expansion and contraction) – we measure the dimensions (the length, the width, and the thickness) of the specimen before and after the alternating humidity and temperature exposure. The change in the dimensions (in %) is reported. We report the dimensional change and the effect on the fit.
• Adhesion measurement (ASTM D3359 / NTC 5662 – for the coating adhesion) – we measure the adhesion of the coating (or the paint) after the alternating humidity and temperature exposure, using the cross‑cut test or the pull‑off test. The adhesion rating is reported. We report the adhesion rating and the loss of adhesion.
• Hardness measurement (ASTM D2240 / NTC 5663 – for the material softening) – we measure the hardness (Shore A, Shore D, or Rockwell) of the specimen before and after the alternating humidity and temperature exposure. A decrease in the hardness indicates a softening of the material. We report the hardness change and the softening effect.
• Microstructural examination (ASTM E3 / NTC 5664 – for the changes in the microstructure) – we examine the microstructure of the material (the grain size, the phase distribution, and the presence of voids) using optical microscopy and SEM, before and after the test. The microstructural changes are correlated with the degradation. We report the microstructural changes and the degradation mechanism.

Test Report and Recognition in the Croatian Industrial, Automotive, and Construction Sector

All procedures described are within the scope of our ISO/IEC 17025 accreditation, with equipment calibrated periodically (temperature‑humidity chambers, data loggers, microscopes, and testing machines) and traceability to international standards (NIST, PTB). Our test reports are issued in English (with a Croatian summary available on request) and include:

• Full identification of the test item (product name, model, serial number, material, and intended application).
• Detailed description of the test methods applied (IEC/ISO/ASTM/HRN EN/NTC standards, test conditions, temperature, humidity, and duration).
• Numerical results: insulation resistance (MΩ), leakage current (mA), water absorption (%), dimensional change (%), hardness (Shore/HRC), and adhesion rating (5B to 0B).
• Graphical data: temperature‑humidity vs. time profiles, electrical parameter vs. time curves, and degradation vs. time curves.
• Comparative tables against the values specified by the client or against the limits of the relevant standards (IEC 60068‑2‑30, IEC 60068‑2‑38, ISO 16750‑4, HRN EN 60068‑2‑30, and the requirements of the HZN, Ministarstvo graditeljstva, and Državni inspektorat).
• Photographs and micrographs (SEM) of the test item before and after the test, showing the corrosion, the blistering, the cracking, or the delamination.
• Recommendations for material selection, design improvement, and quality control measures to enhance the alternating humidity and temperature resistance.
• Expanded uncertainty (k=2) for all key measurements, calculated according to the ISO/IEC 98‑3 Guide.

These reports are fully accepted by the Hrvatski zavod za norme (HZN) for the verification of product conformity, by the Ministarstvo gospodarstva i održivog razvoja for industrial and energy compliance, by the Državni inspektorat for market surveillance, by the Ministarstvo graditeljstva i prostornoga uređenja for building materials approval, and by the Carinska uprava (Croatian Customs) for tariff classification and quality verification in the import of materials and components. Additionally, we offer consulting services for the selection of materials with high alternating humidity and temperature resistance, the design of environmentally robust products, and the implementation of quality control programs for environmental durability, contributing to the reliability, safety, and longevity of products in the diverse and growing Croatian market, from the coastal and maritime industries to the continental manufacturing and construction sectors.