Hidden Risks: Contamination Along the Process Chain/Value Chain
In-depth look at sources of contamination and how to characterize them
Contamination generally refers to the introduction of unwanted substances into a system, onto a surface, or into a material. They can occur in many areas, such as the environment (e.g., water or air pollution), food production (e.g., due to bacteria or foreign substances), medicine (e.g., contamination of sterile instruments), and in technical and industrial processes (PVD/CVD coating processes, cleaning steps, and further processing such as extrusion or forming).
In a technical context, contamination refers to unwanted deposits of organic or inorganic substances on the surfaces of products or within processes. These deposits arise either from internal causes (such as the diffusion of components from the material to the surface) or from external influences (e.g., deposits from the air or through contact with people, tools, or packaging). Such contaminants can significantly alter surface properties and lead to problems in production processes. These include discoloration, altered electrical or chemical properties, as well as adhesion and coating defects (such as craters, spots, or dents), and can even result in the detachment of entire layers (delamination).
Contamination along the value chain
When examining the value chain with a focus on potential contamination, various scenarios can be identified.
1) Contamination can occur as early as the raw material production stage. For example, catalyst residues from the synthesis process may remain in the material, which can have a significant impact during further processing or on the product’s properties.
2) During the further processing of raw materials, additional contamination may occur due to release agents from machinery, tool wear, or thermal decomposition processes.
3) Another important but often overlooked factor in identifying sources of contamination along the process chain is the cleaning step. While this step is essential for removing dirt or other deposits from surfaces, residual cleaning or disinfectant agents can also lead to problems during further processing or affect product properties.
4) There is also a risk of contamination when handling goods and materials, for example through the transfer of plasticizers from gloves or antistatic agents from packaging films onto surfaces.
5) Despite often high cleanliness standards and monitoring of room and air quality, aerosols, particles, or other volatile substances can land on products and become adsorbed there.
6) Storage also carries risks. For example, the use of fungicides under certain conditions or the selection of unsuitable packaging materials can lead to the formation of coatings on surfaces.
Case studies
- The toxic and reactive compound phosphine is released from phosphorus-containing flame retardants on the one hand, and is also used specifically as a pesticide on container ships on the other. Through adsorption on electrical contact surfaces, polyphosphates can form, leading to high electrical resistance and ultimately to the failure of electronic components.
- Lubricants are essential industrial aids, but when they contaminate process surfaces in undesirable locations, they can lead to coating defects (see also the application example “Failure Analysis: Incorrect Selection of Lubricants”). Typical consequences include defects such as craters, dents, or pitting, as well as widespread delamination and wetting issues.
- Deposits on plastic surfaces (e.g., residues from cleaning or disinfecting agents; see application example: Damage caused by QAV) can lead to material degradation. A well-known example is environmental stress cracking (ESC), which causes cracking and ultimately fractures in the material.
- Heavy layers of contamination on the surfaces of raw parts (e.g., from lubricants or antistatic agents) can interfere with physical pretreatments such as flame treatment, plasma treatment, or corona treatment. This prevents the necessary increase in surface energy, which in turn can lead to widespread coating defects. In the manufacture of pharmaceutical products, QAVs can also end up on packaging or even on the medications themselves. Consequently, unwanted contamination occurs.
TOF-SIMS and FTIR: established methods for identifying and characterizing contaminants
Time-of-flight secondary ion mass spectrometry (TOF-SIMS) and Fourier-transform infrared spectroscopy (FTIR) have become particularly well-established methods for analyzing the chemical composition and identifying contaminants on process and product surfaces. These methods enable the detection of even the slightest traces of contamination and allow for unambiguous chemical identification—even in complex material systems.
Even very small sample quantities are sufficient for analysis, such as microparticles, thin coatings on surfaces, or minute droplets. In many cases, sampling can be performed non-destructively, for example by wiping the surface with special cotton swabs or filter paper, by directly analyzing material surfaces, or by using adsorption targets in the context of outgassing or aerosol analyses. An additional advantage: It offers customers the option of performing sampling themselves directly on-site for complex, large-scale, or non-transportable components.
Summary: Contaminants and Their Chemical Identification
Contamination can occur in various forms throughout the entire value chain. It can result from raw materials, process steps, cleaning procedures, handling, environmental conditions, as well as storage and transportation. Even despite high purity and quality standards, contaminants—whether particles, chemical residues, or compounds adsorbed from the ambient air—can end up on materials and cause undesirable consequences. This can result in quality issues such as surface defects and material degradation, or malfunctions in technical and electronic systems.
Analytical testing makes it possible to identify the sources and causes of contamination—a critical step for businesses. In particular, the highly sensitive TOF-SIMS mass spectrometry and FTIR infrared spectroscopy enable the precise characterization of the chemical composition of unknown substances. Both individual substances and complex mixtures can be analyzed. Another advantage is that even the smallest traces can be detected. Through appropriate sampling and sample preparation, these methods provide an efficient and practical means of chemical characterization, even for complex or large-scale systems, thereby making a decisive contribution to quality assurance (including preventive measures) and process optimization. In addition to identifying the cause, they play a crucial role in localization. In this context, comparing results with reference standards or deploying and analyzing aerosol targets (in-house method) is particularly effective for spatially pinpointing the source of contamination.
Please contact us to learn more about our work in surface analysis as well as materials and failure analysis—we would be happy to provide you with practical application examples related to these fields.
