Testing and Research Laboratory
In 1990 we established our research laboratory. It is specially designed for the tasks of researching wiping cleaning procedures and measuring surface cleanliness.
Our research focus:
It is our self-chosen goal to understand the mechanics and all other chemical and physical phenomena of the wiping cleaning process up to the dimensions of nanotechnology. Furthermore, our self-imposed tasks include::
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The support of users with questions on wiping cleaning procedures
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The continuous improvement of the production processes
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The qualification of new materials with regard to their suitability for use in clean rooms and controlled environments (suitability for cleanliness, suitability for clean rooms, suitability for specification)
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The operation and maintenance of an extensive range of instruments - 50 measuring and testing devices
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The development of specialised test methods for hi-tech cleaning wipers and cleanliness work
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The publication of the results in specialist lectures, articles and specialist books
In order to achieve our research goals, the Clear & Clean research laboratory has been equipped with state-of-the-art instruments over the years. In the meantime, more than 40 different analysis systems are available for the varied and diverse questions of our users, which are described below.
MICROSCOPY
Scanning electron microscope (with EDX)
Electron microscope in PC format for images with real magnification of up to 20,000 times. With this device, the very fine yarn and filament structures of hi-tech wipers can be visualized on a micrometer scale. In addition, the finest traces of contamination can be displayed and their element structure determined using energy-dispersive X-ray analysis (EDX). The origin of the particles can often be determined based on the particle morphology and combination of elements. Finally, the biological degradation of high-tech cleaning nonwovens in the soil (natural composting) was documented and visualized over a period of several weeks.
Light microscopes
For many visualization tasks in technology and science, light microscopy is the method of choice for solving problems in clean technology and elsewhere. The micro-structures of high-tech cleaning wipes can be displayed very well using various methods. This includes, for example, optical particle analyzes on surfaces with brightfield, darkfield and fluorescence and interference contrast. In addition, larger surfaces can be displayed very sharply using automatically lined up (stitched) recordings and video recordings of chronological sequences can be made. The focus stacking technique allows us to bypass the depth of field limitations of optical microscopy and to achieve true-color visualizations with the sharpness that is familiar from electron microscopic images.
DIC microscope (according to Normarski)
The differential interference contrast microscope is particularly useful where low-contrast, layered surface contaminants such as oil, grease and time-dependent haze (TDH) are to be imaged with high contrast. At the same time, differential interference contrast (DIC) can be used to select, count and view individual particles embedded in the surface film.
In the method, optical path length differences in the object being viewed are converted into brightness differences inherent in the image. This leads to impressive, almost three-dimensional imaging. Appropriate filter combinations can be used to precisely determine the contrast and colour of the images.
Scanning force microscope (AFM)
We use the atomic force microscope to research the properties of various surfaces (wafers, glass, polymer yarns, filaments in ultra-pure cloths) in the nanometer range after we have cleaned them in the CO2 plasma. This method is used to determine the cleaning effectiveness of high-tech cleaning cloths for nano-layers. Another important area is research into the formation of grooves through wiping cleaning procedures when cleaning scratch-sensitive surfaces (see PUB No. 32: Reduction of surface quality through wiping cleaning - grooves and scratching on functional surfaces, Lounges 2015, Stuttgart May 20, 2015 ).
SEM sample drying device
Moist samples for the electron microscopic representation of surfaces have the property of changing their position in a high vacuum, which then results in blurred images. A special device for sample dehydration can help. The samples can be freed of water fully automatically. The process is very gentle, so that sensitive biological microscopy specimens such as insects, plants, pollen and tissue sections can also be processed before they are coated with a thin layer of gold or platinum to enable brilliant SEM images.
Auto sputter coater
A device for the automatic coating of non-conductive samples of electron microscopy with gold, gold / palladium, silver and other metals. Gold coatings in particular result in surfaces that conduct electricity very well, enabling sharp SEM images at high magnification scales. The desired coating thickness can be set on the device in the range of 1 - 50 nm. The coating progression is shown on a display. Due to the magnetron head located at the bottom, the device is also suitable for „cold“ sample coatings. For all EDX analyses that may follow the coating, it must be taken into account that a gold layer applied to the sample can falsify any gold components that may be present in the sample. Moreover, near the gold line (M) there are also sulphur (K), molybdenum (L) and niobium (L), which can overlay the gold line.
No information available
CHEMICAL ANALYSIS
Gas chromatograph with mass spectrometer
With the gas chromatograph and a headspace autosampler for outgassing analysis, clean technology consumables – for example ultra-pure wiping agents, gloves, overalls and paper – can be tested for outgassing and their constituents chemically analysed in the trace range. Even the smallest traces of outgassing in the ppb range can be measured with these devices and chemically identified using their mass spectra. In this way, undesirable contaminants such as mineral spinning oils, lubricants, surfactants, silicone oils and softeners in textile materials can be identified and weighted according to individual species.
Solid phase micro-extraction probe (SPME)
Solid-phase micro-extraction according to Pawliszyn (Solid-Phase Micro Extraction SPME) is a detection method for determining the accumulation of chemical substances in the ultra-trace range. By absorbing species on a storage thread, the detection limit of a GCMS analysis can be reduced by a factor of 25.
Specifically, we use SPME-GC / MS to determine the total outgassing of hi-tech cleaning cloths, overalls, mops and breathing masks at test temperatures of 25 ° C, alternatively 90 ° C in total. The advantage of the SPME technology is the gain in measurement time that is automatically associated with this technology.
TOC analyzer - total organic carbon
We divide industrial purity validation into an active substance-specific and an active-substance-nonspecific type. (Active-substance-nonspecific means that the individual active ingredients are not shown separately, but are only available as sum parameters). In the active substance-nonspecific purity validation for the analysis of impurities in water such as laboratory water, TOC analysis has become the most widely used method. It is the method of choice both for purity testing of ultrapure water as well as for the cleaning validation of equipment and finished products. This applies in particular if the total contamination as a sum parameter with a detection limit of 2 ppb is sufficient for the set test objective.
FTIR spectrometer
FTIR spectrometers are devices for the analysis of organic substances. They enable the chemical analysis of extracts from high-tech cleaning wipes, gloves, overalls, coated papers or other clean technology consumables within seconds. In addition, a test method has been developed in our laboratory which enables the identification of wiping agent residues on surfaces after wiping cleaning procedures. While the transmission FTIR technology is based on the irradiation of a medium in special pellets, it is possible with the aid of the so-called ATR technology (attenuated total reflectance), to analyse non-transparent substances such as oil and polymer layers, paint applications, but also liquid layers, condensates and TDH (time dependent haze).
Capillary electrophoresis measuring station
Device for determining the ion content of porous materials such as cleaning cloths down to the ppm range. The lowest possible ancation and cation content in the pure technology consumables is particularly important for semiconductor production and the aerospace industry. That is why we decontaminate our hi-tech cleaning wipes using specially prepared, low-ion water with a quality of 18.2 MOhm. The pure technology consumables are first extracted in DI water to determine the ion content and the eluate is analyzed by capillary electrophoresis or ion chromatography for the ions present. Capillary electrophoresis is an analytical separation method in a liquid medium to determine charged particles.
Laser fluorescence measuring device
Device for measuring the fluorescence of organic layers on surfaces (contamination), which is caused by illumination with contaminants or special test liquids with UV light of wavelengths from 266 or 355 nm and fluoresces at 405 nm. This instrument is used for surface analysis and to determine the cleaning effectiveness according to Labuda, in which the automatic removal of a fluorescent oil layer by high-tech cleaning wipes from a rotating test surface is measured as a function of time. The laser fluorescence measuring device works in conjunction with the rotary wiper simulator Mark III.
Conductivity meter
The conductivity and the pH value are important basic parameters when examining water samples. We use it to analyze the washing liquor during the aquatic decontamination of our hi-tech cleaning wipes. The pH value is a measure of how acidic or alkaline a solution is. While the value pH 7 means that the solution is chemically neutral, values of 7-14 pH mean an alkaline (basic) environment and values of 0 - 7 pH mean an acidic one. A highly alkaline wash liquor is desirable in order to obtain a satisfactory degree of chemical washout. For high-purity hi-tech wipes, however, a pH-neutral quality is often desired.
No information available
Microwave extraction system
System for microwave-assisted extraction of chemical components from wiping agents, overalls, respiratory masks and other clean technology consumables. The chemical residues in cleaning wipes and other porous products are often only found there in very low concentration. A microwave extraction system is used to achieve a high concentration of the sought-after species in the eluate. This can then be analysed by means of FTIR spectroscopy, total organic carbon analysis (TOC), GCMS or capillary electrophoresis. A significant advantage of this extraction method is the significant time saving compared to the classic Soxhlet extraction.
Ultrapure water generator
Ultrapure water is the most common and most indispensable medium used in the laboratory for the analysis of impurities. Test water of the highest quality (18.2 Mohm) is required for testing the particle release of high-tech cleaning agents in the daily quality control. We therefore use an ultrapure water system that produces both particle-free and ion-free laboratory water. DI water of this quality can be used as an extraction medium to measure base values for trace analysis in the ppb range.
The water treatment technology comprises:
TOC content <50 ppb
Microorganisms <1 CFU / l
Particles less than 1 particle / ml
Production: 2.0 l / min
No information available
Liquid tensiometer
This device can be used to measure the surface tension of liquids. For this purpose, the force is determined which is necessary to lift a fine platinum wire out of the liquid. Since the surface tension of DI water can be reduced considerably by surfactants and detergents, this method can be used to examine wiping agents for such residues by immersion. This is a time-saving and very reliable test method, as the platinum wire can be repeatedly brought into an ultra-pure state by annealing over a gas flame. The measurement time is less than 1 minute.
Precision and analytical balances
Fine and micro scales for the determination of substance content and deposits on surfaces are indispensable instruments in a chemistry and materials laboratory. In principle, there are two different types of mass determination in the µg range: those with a mechanical precision measuring cell and others with a piezo-electric crystal plate. The former also work in the lower µg range. Such instruments are indispensable for the gravimetric determination of filtrates and residues after wiping cleaning processes. Because of the required weighing and repeat accuracy, they are equipped with a temperature control. This allows fingerprints as well as traces of abrasion and material imprints from cleaning wipes, nitrile gloves, etc. to be determined gravimetrically on surfaces of different roughness.
Soxhlet extraction apparatus
A classic glass instrument for the chemical extraction of textile and other porous materials. The extraction performance of this known process is almost unmatched to this day. It is time consuming, however. Therefore, these extraction devices are increasingly being replaced by devices of the microwave extraction technology, by means of which similar extraction results can be achieved in a fraction of the time. The advantage of a Soxhlet apparatus is that you can let the extraction run automatically overnight.
UV / VIS spectrometer
Spectrometer for the analysis of visible and ultraviolet light. Many organic molecules show absorption bands, especially at ultraviolet wavelengths, which can be used for a direct quantification of compounds in a solution. Using this method, z. B. the concentration of polyester oligomers in a cloth extract can be precisely determined. In addition, a color reaction was developed for many analytes so that they can be determined indirectly after adding the color reagent. For example, the concentration of surfactants in water or in extracts can be measured indirectly.
No information available
PARTICLE ANALYSIS
Airborne Particle Counter
Various laser particle counters for measuring airborne particles. The particle counters can be used with other test equipment (e.g. with the Labuda Walk Simulator) to investigate the release of particles in application scenarios.
No information available
portable surface particle counter according to Klumpp
The measuring device is well suited for determining the number and size of particles on surfaces with low roughness. The measurement result is visualised on a live monitor and displayed numerically. At the same time, a printout or data storage on a USB stick takes place. The measuring principle corresponds to ISO 14644-9. The measurable particle size is limited to a Feret diameter of 2 µm in the lower range and ends at 2000 µm in the upper range. The active measuring area is 5 x 7 mm with a measuring time of <5 seconds. Because the measuring range is limited to 2 µm, the counter is only suitable to a limited extent for assessing the use-related release of particles from clean technology consumables. On the other hand, it is well suited for assessing the release of fibre fragments from textile materials.
Liquid particle counter
Laser liquid particle counter for testing the particle release of wiping agents and other clean technology consumables such as gloves, mops and paper after liquid immersion. With this technique, the number and size distribution of particles in test liquids such as DI water or DI water-alcohol mixtures can be analyzed quickly and easily. Liquid particle counters are among the most important quality assurance devices in clean technology. The counter in our laboratory works in the particle size range of 0.5-350 μm Feret diameter. The test volume is generously dimensioned at 1-10 ml. The concentration range of the counter is 0-9,000 parts / ml. Liquid extraction begins automatically after a suction cannula has been lowered into the sample vessel.
Counter for airborne nanoparticles
This instrument extends the range of our determination options for airborne particles down to approx. 5 nm. It is therefore now possible for us to measure the release of nanoparticles from high-tech cleaning cloths, gloves and papers. Particles of this size can pass through the lungs. Therefore, it makes sense to determine the lung-effective surface (LDSA-Lung-Deposited Surface Area) of the released nano-particles directly. This device is particularly important against the background of the intensive research activities that have taken place everywhere in order to assess the degree of risk from the concentration of nanoparticles in the air at the workplace.
No information available
Nanoparticles in a liquid medium
The distribution and size determination of nanoparticles in liquid media is a challenge for modern measurement technology. Our aim is to detect the nanometric particle content in the three-dimensional structures of textile and other porous cleaning products. The DLS - dynamic light scattering measuring principle of our analyser is based on Braun‘s movement. The particle mobility can be calculated from the fluctuation of the scattered light intensity, and the particle size can be calculated using the Stokes-Einstein formula. The device enables particle size determinations from the lower nanometre range to hydrodynamic diameters of a few micrometres. The sample is applied directly to a glass surface as a liquid layer of a defined thickness.
SURFACE ANALYSIS
Ellipsometer
The instrument enables layer thickness determinations on test surfaces down to the sub-monolayer range (0.5 to 10 nanometers). This is the only way to measure the effects of wiping precision cleaning with our most effective cleaning wipes (Microweb UDG, Sonit MDH) in the nanometer range. For example, 0.5 nm thin film contamination on wafer surfaces can be determined. The device is suitable for so-called mapping scans. In the area of 50 x 50 mm, informative, nanometric topographies can be graphically represented and the mode of action of wiping cleaning processes in the ultra-trace range can be illustrated.
Plasma cleaning system
A continuous supply of energy to a solid matter increases its temperature. It first liquefies before it changes into a gaseous state. With continued energy supply, the atomic shells are broken and a particle mixture of negative electrons and positively charged ions – called plasma – is created. There are always layers of contaminants of a molecular magnitude such as TDH on surfaces. The plasma causes them to dissolve. In purity research, it is not uncommon for coating experiments or procedures of wiping cleaning to start with “absolutely clean” surfaces. Plasma generators and chambers are ideally suited for such experiments. In our laboratory we can check the effect of the plasma cleaning by means of laser fluorescence analysis.
Centrifugal adhesion analysis
There is a particularly practical test method for the contamination of material surfaces through the use of wiping cleaning systems (cleaning wipe, solvents, handling experience). This is the centrifugal adhesion analysis: A cleaning wipe is wiped over a plasma-cleaned test specimen A surface. This may result in the transfer of traces of the textile chemistry process. After this has been attached to its adhesion partner – a test specimen B surface – by means of a selected adhesive, a molecular structure develops between the surfaces involved, the strength of which is determined by the detachment force during the centrifuging process, which indirectly functions as a measure of purity.
Quartz crystal microscale
A piezo-electric ultra-fine scale for measuring very small masses such as moisture films and wipe residues in the nanogram range. Layers with a thickness of just a few nanometres can thus be determined gravimetrically. Applying a mass to a vibrating quartz plate changes its resonance frequency, which correlates precisely with the mass. Wiping cleaning processes often only leave traces of contamination on the cleaned surfaces. Piezo-electric scales are well suited for measuring these traces. This also applies to analytical sampling of traces of material by means of lobule removal and subsequent mass determination in the ng range. This requires ultra-pure textile sections that are free of any foreign matter that can be detached from their fibres or filaments.
No information available
Droplet sink time meter
The group of polymers: polyester, polyamide and polypropylene have naturally water-repellent surfaces. Hi-tech cleaning wipes made from them must therefore be made water-absorbent (hydrophilized) before use. Only then can they be soaked with aqueous solvents. The hydrophilization takes place through the introduction of non-ionic surfactants into the textile material. In this way, the cloth is capable of absorbing water, but at the same time chemically impure. It is therefore advisable to determine exactly the right amount for the surfactant input. The droplet soak time is the key parameter for determining an application-oriented surfactant mass. The device is also suitable for determining the chemical surface purity.
Surface roughness measuring device
Roughness is a surface shape deviation that is specified in DIN 4760. It is an important feature when the roughness of a material surface generates more or less material abrasion due to friction against another surface. We measure topographies by diamond needle scanning but also, e.g. in research institutes by non-contact white light interferometry and laser profilometry. The cleaning effectiveness of cleaning wipes, nonwovens and foams is largely determined by the roughness of the surface to be cleaned. ISO 1302 is the valid standard in Germany for specifying the condition of workpiece surfaces. Wipe abrasion tests are carried out in our laboratory on surfaces whose topography is specified in accordance with the above standards.
No information available
TEXTILE TESTS
Maximum tensile force / elongation measuring device
The tensile strength and elongation of textiles and papers can be easily performed with this device in accordance with the tensile test according to DIN EN ISO 13934-1 and 2. For this purpose, the test specimen is loaded with an increasing tensile load and the elongation is measured at the same time. The test ends when the test item tears. This test is actually intended for tissue. Nonwovens should be carried out according to DIN EN ISO 9073-18: 2008-08 Textile test method for nonwovens Part 18: Determination of the maximum tensile strength and maximum tensile strength elongation of nonwovens with the grab tensile test.
Mechanical thickness measuring device
A device for determining the thickness of textile materials, foams and papers. For this purpose, a test weight with a defined contact surface is briefly applied to the test object during the distance measurement in order to ensure a high level of reproducibility of the measurement and to ensure that the fiber web on the surface of textile materials does not falsify the measurement in an inadmissible manner. The paper thickness, on the other hand, is determined according to DIN EN ISO 534. A mean value is formed from 20 individual values. The device is also suitable for thickness measurements according to ASTM. The device can be calibrated using a precision feeler gauge with 20 sheets.
Surface electrical resistance
The electrical surface resistance of textile fabrics and paper can be a measure of their electrostatic discharge capacity or chargeability. Since the basic materials of high-tech cleaning wipes and cleanroom papers are electrical non-conductors, the resistances involved are very high, up to 1015 ohm. For example, this resistance decreases rapidly due to increased ambient humidity. The resistance measuring bridge shown is also used for dielectric tests in connection with the chargeability of porous materials, in particular paper and nonwovens.
No information available
Electrostatic purity measurement according to Labuda
The electrical discharge quotient after a defined electrostatic charge correlates with some textile materials with their chemical purity or their degree of leaching. The prerequisites for the measurement are constant material and ambient humidity values. This means: Textile materials lose their measurement time within 1 minute, the less electrical charge they are, the purer they are.
On the basis of this knowledge, our quality laboratory has developed a test procedure for the chemical purity of our wipes. The test time for a single cleaning cloth is just 30 seconds. The method was tested in our laboratory for two years on the basis of defined contaminated test objects and found to be sufficiently accurate.
Details in preparation
MATERIAL TESTING SYSTEMS
Linear wiping simulator Mark I
Simulator for the implementation of reproducible wiping processes for the scientific investigation of the mass removal of specifically contaminated surfaces. This includes glass, metal and plastic plates as well as different contaminant material. For example, the removal of particulate and filmic contaminants and their back-transfer to object surfaces can be investigated as part of wiping cleaning procedures. The influences of the wiping speed and the vertical pressure on the cleaning effectiveness of high-tech cleaning cloths can also be examined very well in this way.
Publication (PDF)
Linear wiping simulator Mark II-A
The linear wiping simulator type MarkII-A with a sliding plate made of glass can optionally be provided with a metallic sliding plate (type MarkII-B). In this plate there is a recess for the fitting of highly pure or deliberately contaminated quartz oscillator platelets. The platelet is compatible with the quartz scale type QCM-200. The targeted contamination of the metallic sliding plate or the surface of the quartz platelet is followed by a wiping cleaning procedure using high-tech cleaning wipes of various types. A special feature of this system is that a high-speed camera can be synchronised with the movement of the test specimen underneath a transparent test surface.
Publication (PDF)
Rotation wiping simulator Mark II according to Labuda
The simulator was developed by Labuda and Schöttle with the aim of determining the particle and fiber abrasion of wiping agents and foams during wiping cleaning processes over surfaces with increased roughness and special topographies. The principle works with four bowls made of V4A steel, the bottom of which has a higher roughness level. The rotor, which is covered with a cloth sample and is under defined pressure, moves in it. After a predetermined number of rotations, the bowl with the abraded particles it contains is removed from the simulator and filled with particle-free DE water. The DE water is examined for the number and distribution of particles either microscopically or with the help of a liquid particle counter.
Publication (PDF)
Rotation wiping simulator Mark III according to Labuda
In 2007, Labuda and Schöttle presented the Mk III rotary wiping simulator, with which it is now possible to measure the cleaning effectiveness of various high-tech cleaning wipes for low-viscosity contaminants (mineral oil). A rotating roller made of VA steel with a defined surface roughness is deliberately contaminated by applying a thin film of oil. The removal of the oil film by a cleaning cloth (test piece) pressed against the rotating roller is measured continuously. This is done with the help of laser fluorescence measurement. With the same apparatus it is also possible to determine the cleaning effectiveness of high-tech cleaning cloths per unit of time. For the first time, performance parameters for cleaning wipes can be defined. This means that high-tech cleaning cloths can be used, for example. B. Classify according to precision, fine and standard cleaning wipes.
Publication (PDF)
Scattered light particle visualization * NEW *
Dual oblique light lamp for the visualization of particles, fiber fragments and material imprints on collector plates (1) and any smooth surfaces (2). With this lamp, the particle release from various high-tech wipes can be examined quickly and easily. If necessary, the evaporation residue of solvents can also be made visible. The device is ideally combined with the CC collector plate CC 900. The device can also be placed on the stage of a microscope so that the particles, traces etc. on the collector plate can be viewed and recorded photographically or automatically counted.
CC 900 collector plate
Versatile collector glass plate with black background for the visualisation of sedimentation and imprint particles, filmic contamination, material imprints, drying residues and time-dependent haze. The visualisation can e.g. be done with the light microscope in darkfield, fluorescence or in differential interference contrast. Labuda et al. have described a test method for the CC collector plate with which, among other things, the textile purity of high-tech cleaning wipes can be assessed in the as-delivered condition. The collector plate can also be contaminated in a targeted manner, for example with a thin film of oil or grease, and after a wiping cleaning process, the cleaning effectiveness of the corresponding wiping agent can be analysed.
Publication (PDF)