How to Test and Verify Low Outgassing Performance in Adhesives
Low outgassing adhesives are essential for industries that require absolute cleanliness, stability, and reliability, especially in aerospace, optics, semiconductors, medical devices, and precision electronics. Even microscopic amounts of volatile materials released during curing or long-term use can contaminate sensitive surfaces, degrade optical clarity, or interfere with high-vacuum systems. Because of this, testing and verification are critical before integrating any adhesive into a high-performance manufacturing environment. Understanding how to properly evaluate outgassing behavior ensures that products remain stable, safe, and compliant with international standards. This article explains how low outgassing performance is tested, why it matters, and how manufacturers in Malaysia can ensure their adhesives meet the highest reliability requirements.
Understanding Low Outgassing and Its Importance
Outgassing refers to the release of volatile compounds trapped inside an adhesive’s polymer matrix. During exposure to elevated temperatures or vacuum environments, these volatiles evaporate and may condense on nearby components. While this may seem insignificant in ordinary applications, it can cause serious issues in precision engineering. For example, in optical instruments such as cameras, telescopes, and lasers, even a thin film of condensed material can obstruct light transmission, reduce image quality, and create long-term defects. In aerospace environments, contamination on sensors, mirrors, and thermal control surfaces can impair mission-critical performance. Semiconductor manufacturing relies on contamination-free cleanrooms where any unexpected residue can affect yield and product consistency. Therefore, adhesives selected for these industries must satisfy strict outgassing standards to ensure reliability and long-term stability.
International Standards for Low Outgassing Adhesives
To evaluate the suitability of adhesives for high-precision environments, international organizations have established standardized testing methods. One of the most recognized benchmarks is NASA’s ASTM E595 standard, which measures volatile release of materials under vacuum at high temperature. This standard identifies two key metrics: Total Mass Loss, which measures how much material evaporates from the sample, and Collected Volatile Condensable Material, which indicates how much of that evaporated material condenses onto a cold surface. Materials that meet NASA’s limits are considered safe for use in spacecraft, satellites, and optical instruments. The European Space Agency also has its own standards, such as ECSS-Q-ST-70-02C, which further define acceptable material characteristics for space applications. These standards give manufacturers confidence that an adhesive will not contaminate critical components during operation.
Preparing Adhesive Samples for Outgassing Testing
Verifying low outgassing performance begins with preparing the adhesive sample according to the test method. Samples must be weighed carefully on high-precision balances to ensure accurate mass readings before and after testing. The adhesive is normally cured according to the manufacturer’s recommended conditions, as incomplete curing can dramatically increase volatile release. Once prepared, the sample is placed inside a vacuum chamber along with a cooled collector plate designed to trap condensed volatiles during the test. Proper preparation ensures reproducibility and accurate evaluation of the adhesive’s actual performance under simulated operating conditions.
Conducting Vacuum Outgassing Tests
The core of the testing process involves exposing the adhesive sample to a controlled vacuum at elevated temperature, often around 125°C, for a period of 24 hours. During this time, any volatile components evaporate from the sample into the vacuum environment. At the same time, a cold collector plate, typically cooled to near 25°C, captures any volatiles that condense on its surface. The adhesive sample is weighed again at the end of the test to determine how much mass was lost. The collector plate is also weighed to measure how much condensed volatile material was deposited. These measurements provide the necessary data to compute Total Mass Loss and Collected Volatile Condensable Material, the two critical indicators of low outgassing behavior. The results help engineers determine whether the adhesive is suitable for use in sensitive electronic, optical, or aerospace environments.
Interpreting Outgassing Results
Interpreting the results of low outgassing tests requires understanding the acceptable limits set by international standards. For example, NASA’s ASTM E595 standard dictates that Total Mass Loss should be less than 1 percent and Collected Volatile Condensable Material should be less than 0.1 percent. Adhesives that meet or exceed these requirements are considered low outgassing and are safe for use in vacuum and optical systems. However, interpreting the numbers also involves evaluating repeatability and environmental stability. Some adhesives may meet the limits at one curing temperature but fail at another, which may indicate formulation sensitivity. Comprehensive interpretation also considers the adhesive’s chemical structure, curing mechanism, and long-term aging performance. Manufacturers and engineers should analyze both the numerical results and the adhesive’s practical behavior under operating conditions.
Additional Tests to Confirm Low Outgassing Performance
Beyond standard vacuum outgassing tests, additional characterization techniques can be used to verify adhesive stability. Thermal Gravimetric Analysis is a powerful method that tracks mass changes of the adhesive as it is heated gradually. This helps identify decomposition points or residual volatiles that may not show up in standard short-duration tests. Gas Chromatography–Mass Spectrometry can be used to identify the exact chemical composition of volatiles released, which is useful for highly sensitive optical or semiconductor applications. Differential Scanning Calorimetry helps ensure the adhesive has fully cured, as incomplete curing is one of the most common causes of elevated outgassing. Combining these analytical methods provides a comprehensive view of the adhesive’s long-term stability and ensures confidence in its suitability for precision applications.
Environmental Factors That Influence Outgassing Results
Several environmental factors can influence outgassing performance. Humidity plays a significant role, especially in tropical climates like Malaysia, as moisture absorption increases the likelihood of volatile release during testing or actual usage. Temperature also affects outgassing, as higher temperatures accelerate evaporation of trapped compounds. Cleanliness is another key factor because contamination on the adhesive surface can vaporize during heating and produce misleading results. For these reasons, adhesives intended for use in Malaysia or other high-humidity environments must be evaluated under controlled conditions that accurately simulate real-world stresses. Testing under different environmental settings allows manufacturers to assess performance consistency across various operating conditions.
Why Testing Matters for High-Precision Industries
Testing low outgassing performance is crucial for ensuring device reliability in mission-critical applications. In aerospace systems, contamination on sensors and optical instruments can compromise the functionality of satellites, robotics, or navigation equipment. In the semiconductor industry, even microscopic surface contamination can reduce wafer yield or disrupt lithography processes. Optical applications such as cameras, microscopes, fiber optic components, and laser systems require extreme clarity that can only be achieved with contamination-free bonding materials. Medical devices such as diagnostic equipment and implantable sensors also rely heavily on low-outgassing adhesives to ensure safety and precision. Testing therefore ensures that the adhesive performs consistently over time and does not compromise the functionality of sensitive components.
How Pacific Adhesive Systems Supports Low Outgassing Requirements
Pacific Adhesive Systems (M) Sdn Bhd provides advanced low outgassing adhesives designed for aerospace, electronics, optical and semiconductor applications. The company offers UV-curable epoxies, low-outgassing epoxy systems, and precision bonding materials formulated for environments that demand strict contamination control. In addition to supplying materials, Pacific Adhesive Systems assists manufacturers with technical guidance, testing support, application recommendations, and process optimization. Their adhesives are engineered to meet NASA and international outgassing specifications, ensuring that Malaysian manufacturers achieve global-standard performance in high-precision production environments.
Conclusion
Testing and verifying low outgassing performance is essential for ensuring the cleanliness, reliability, and safety of high-precision electronics, aerospace components, and optical systems. By understanding the principles of outgassing, following internationally recognized standards, and using proper testing methods such as vacuum outgassing, Thermal Gravimetric Analysis, and chemical analysis, manufacturers can accurately evaluate adhesive performance. Environmental considerations such as humidity, temperature, and contamination must also be integrated into testing procedures, especially in tropical regions like Malaysia. With the right expertise and materials from trusted suppliers such as Pacific Adhesive Systems (M) Sdn Bhd, engineers can confidently select adhesives that deliver consistent performance, protect sensitive components, and meet the rigorous demands of modern manufacturing.
