fischerscope

No.

12 01

10/09

FISCHER NEWSLETTER Coating Thickness

Material Analysis

Microhardness

Material Testing

«editorial»

«closer examination»

Dear Readers,

Fischer spreads its involvement with education institutions in SEA

Once you have read this issue of FISCHERSCOPE, you will realise that the main focus of our efforts is rising to the challenge of new measurement tasks. Our new portable X-ray fluorescence instrument enables you to make measurements on large objects. FISCHER has implemented a new concept in the development of this instrument: a fully-fledged X-ray device with extensive functions in a mobile format. For microscopic specimens, there is progress in the measurement of extremely small structures in semiconductor technology. And in the inline measurement sector, IfG has developed an X-ray diffraction method that can determine the concentrations of various phases of an element in powders. Other innovations presented in this issue are long-term nano indentation and a new generation of conductivity meters. Finally, I am pleased to introduce our worldwide service organisation and what they offer. We hope you enjoy reading this issue!

Walter Mittelholzer CEO Helmut Fischer Holding AG Helmut Fischer AG

This year Fischer starts activities in Malaysia with seminars in Malaysian Higher Institution of Education, the first of the series involved Multimedia University with campuses in three locations in Malaysia and a student population of about 20,000 undergraduate and post graduate students. MMU’s is a highly ranked local Technical University with strong links to Telekom Malaysia the government linked telecommunications services provider, key research and development subjects that MMU is involved in other than telecommunications, is radar, image processing, metallurgy, material science. There was keen interest expressed by Professor Koo of Multimedia University on Automation of Measurements, material analysis and analysis of contaminants. A total of 40 students both under graduates and postgraduates with 5 staff members attended the seminar conducted where Fischer show cased pattern recognition and various automated measurement knowhow. A lively discussion after the presentation was held with staff members and postgraduate participants on possible collaborative work and measurement methods, subjects of key interest was possible usage of some of Fischer’s measurement technology to be integrated into measurement systems that MMU does customise for local industries.

«information from practice»

The new FISCHERSCOPE® X-RAY XAN® 500: mobile coating thickness measurement and material analysis from FISCHER the mobile benchtop unit (Figure 2) under all conditions. The hand-held unit can easily be detached from the benchtop unit (see Figure 3) to measure large objects or take measurements in awkward places. It is shaped for reliable placement on the specimen to facilitate reproducible measurement of coating thickness or material composition.

1 2 3 4 5 X. S

Cr / µm 0.201 0.199 0.199 0.199 0.201 0.200 0.001

Ni / µm 7.60 7.58 7.58 7.59 7.61 7.59 0.01

Cu / µm 14.53 14.48 14.52 14.48 14.55 14.51 0.03

Table 1: Results of 5 individual coating thickness measurements of 5-seconds each for Cr, Ni and Cu on a chrome-plated trim strip.

1 2 3 4 5 X. S

d / µm 7.44 7.45 7.43 7.46 7.47 7.45 0.01

Ni / % 11.58 11.62 11.59 11.58 11.61 11.60 0.02

Figure 1: Use of the mobile XAN 500 on chrome-plated rotogravure cylinders.

Table 2: Thickness and Ni content of a ZnNi/Fe layer, 5 second measurement.

Device concept The new FISCHERSCOPE® X-RAY XAN® 500 X-ray fluorescence measuring system incorporates FISCHER’s many years of experience with X-ray instruments. It is specifically designed to meet user needs for coating thickness measurement and material analysis in process control and quality control applications. The XAN® 500 enables reliable and precise measurement of small parts in a mobile benchtop unit, measurement of large and bulky parts with a hand-held unit, and easy transport of the entire measuring system.

The XAN® 500 works with a very small and lightweight X-ray tube, which operates with a maximum voltage of 40 kV (optional 50 kV) and 4 W power level. The measuring spot on the specimen is circular with a diameter of approximately 3 mm. An SDD semiconductor detector is used for optimal energy resolution and very short measuring times. The main housing is made from a very light but sturdy magnesium alloy. This results in a weight of 1.5 kg for the hand-held unit (including battery) and approximately 8 kg for the complete benchtop unit.

The mobile benchtop unit is designed to allow small objects to be positioned easily and therefore measured reliably (see Figure 4). From a radiation protection perspective, this ensures safe use of

Figure 2: The mobile

XAN 500. Its protective cover functions simultaneously as instrument housing for benchtop use and carrying case.

FISCHERSCOPE®

The proven WinFTM® software is used for quantitative analysis, giving the XAN® 500 the same basic functionality as all FISCHERSCOPE® X-ray devices. Coating systems, materials and alloy layers can also be analysed easily with the WinFTM® software. The algorithm is based on the fundamental parameter method to obtain reliable measurement data without requiring calibration standards. Extensive functions for statistical evaluation, documentation and exporting measurement data give users the right tools for process control and quality assurance tasks. Applications The XAN® 500 can be used with a wide variety of corrosion protection coatings, decorative coatings and functional coatings in various industrial sectors, including electronics, automotive, aerospace, domestic appliances and many more. An example of a typical application is a chrome-plated trim strip (Table 1), which has a three-layer structure. Even with a measuring time of just five seconds, very good results can be obtained for all three layers.

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Another example is measuring zinc nitride coatings. In this case the nickel content of the coating is also important, along with the coating thickness. Table 2 shows the results with a typical coating. Here again, the repeat

distribution is very good even with a short measuring time. With the new XAN® 500, many coating thickness measurement and material analysis tasks can now be performed “on the go” with customary FISCHER quality.

Dr Bernhard Nensel

Figure 3: Easy removal of the hand-

Figure 4: Once the hand-held device

held unit.

is placed into its case, the whole unit functions as a self-contained measuring system. Shown here: even the positioning and measurement of small objects is straightforward.

«closer examination»

New HT2000 measurement head: nano-indentation on a new time scale The various curves can be attributed to different material properties of the glass specimens; external influences are negligible. The measurements in the second example were taken on an acrylic sheet. The measuring conditions (maximum force and force exposure time) were varied in the test with increasing force, while the test force of 5 mN was held constant for creep measurement after the force was released (Figure 4). Clearly visible differences can be attributed to different initial conditions. This long-term measurement capability creates new options for characterising coatings, in particular soft coatings and materials such as polymers and paints. With the new HT2000 measurement head in combination with either the FISCHERSCOPE® HM2000 positioner or the FISCHERSCOPE® HM2000 S stand option, precision measurements can now be made over a time frame that was previously impossible.

For temperature monitoring and documentation, the measurement head can be equipped with an external temperature sensor to determine the temperature close to the indenter or on the specimen.

Thanks to the excellent temperature stability of the HT2000 in an air-conditioned environment, individual measurements extending over several hours are now possible without any effect on the results from longitudinal expansion of the device. The maximum temperature changed in the vicinity of the indenter is 0.2°C over a ten-hour period, with the applied force being varied between several values from 5 to 2,000 mN at hourly intervals (Figure 2). For the first time, this allows the creep characteristics of materials to be investigated over extended periods without any influence stemming from the instrument. This can be illustrated by two examples. Figure 3 shows the creep behaviour (plastic deformation of the material with constant force) over a period of one hour for various types of glass. The measurements were taken with a Vickers indenter and a test force of 2,000 mN.

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Figure 2: The temperature near the indenter (blue) stays nearly constant over the 10 hours, although the force (green) is varied between 5 and 2000 mN during that time.

FISCHERSCOPE®

Figure 3: At constant temperature, the different creep behaviours of different

Figure 4: The creep behaviour of acrylic at 5 mN (after release of force)

types of glass can be traced back to differences in material. Effects due to

is influenced decisively by the conditions of the preceding hardness

temperature-induced expansion are negligible.

measurement.

Another innovation is improved force and distance resolution. High precision measurements are possible thanks to a noise floor below 175 pm. Naturally, the new measurement head has a USB port for communication with the computer. The status indicator

on the head shows the state of the instrument (switched on and warmed up, for example) at a glance. For more information, visit http://fischerscope.de/nano2b Tanja Haas, MSc Physics Gottfried Bosch

«information from practice»

In situ XRD for routine production processes X-

ra

y

Bragg equation nλ=2dsinθ

n1

θ

d A

B X

n2

dsinθ

Figure 1: The diffraction of a monochromatic X-ray in the crystal lattice follows from the conditions of the Bragg equation.

Measuring process parameters such as temperature, pH, gas concentration or gas pressure at critical process points is now standard practice. In situ monitoring of product characteristics by process-level X-ray analysis is becoming increasingly common in modern production monitoring because it eliminates the time-consuming alternative of quality control in a test laboratory. The Institute for Scientific Instruments (IfG) has more than a decade of experience in process-level X-ray analysis. The use of X-ray fluorescence (XRF) for production monitoring has become established in recent years. We have shown in a process that X-ray diffraction (XRD) is also suitable for quality control of manufactured products.

Figure 2: The WO2 (011) peak is represented as a CCD camera image (upper half) with a graph below it for quantitative analysis. The WO2 concentration can be determined from a calibration curve. The top image shows a WO2 concentration of 77.11% and the bottom image 2.17%.

FISCHERSCOPE®

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In the XRF method, the fluorescent emissions of individual elements excited by X-ray radiation are analysed. Each element emits X-ray radiation at a specific energy level. This provides information about the elementary composition of the specimen. However, only limited conclusions can be drawn regarding the presence of a particular chemical phase, and elements with low atomic numbers are difficult to capture with XRF.

are fulfilled (Figure 1). Each structure generates a unique diffraction pattern, allowing individual crystal phases to be determined and even enabling a clear distinction between compounds with the same elements but different crystal structures. For example, the gypsum (CaSO4* 2 H2O) and gypsum anhydride (CaSO4* 0.5 H2O) phases can be distinguished by their diffraction patterns, as can a pure metal and its oxide.

If the product has crystalline bonds, phase determination is possible with X-ray diffractometry (XRD). In this method the interaction between monochromatic X-ray radiation and the individual crystals of a substance causes diffraction of the radiation from the ordered crystal lattice when the conditions for Bragg diffraction

IfG and H.C. Starck jointly developed an in situ XRD analysis technique for production monitoring of a thermal reduction process in which tungsten oxide is reduced to metallic tungsten powder in the presence of hydrogen. The product contains unwanted tungsten dioxide (WO2) if the reduction is not complete. For measurement, specimens are taken automatically from the product stream at short intervals and fed into a measurement chamber. The unwanted WO2 phase is then determined quantitatively using XRD. After measurement, the powder sample is returned to the product stream and a new specimen can be taken for analysis. XRD measurement is performed with the X-ray tube and the detector positioned at fixed angles to the specimen. The detected image from a CCD camera is converted into a peak intensity, which is a measure of the concentration in mass percentage (Figure 2). A smaller angle range corresponding to the (011) peak of WO2 is used for analysis. WO2 concentrations as low as 0.2% can be detected in the tungsten powder production process.

CC D cam e

ra

Sa

m

pl

e

t re

rie

ve

r

Protec tive housing with X-ray tube

In situ measurements impose high demands on the integration of the analysis system into the process (Figure 3). The entire system is installed in an environment exposed to high temperature, high dust burden and vibration from the production process. Aggressive gases may adhere to the specimens. With the in situ XRD measuring system installed at H.C. Starck, we have shown that these hurdles can be overcome and sustained process analysis in continuous operation is possible. Antje Schmalstieg, MSc Physics Renat Gubzhokov IfG Institute for Scientific Instruments

Figure 3: In situ XRD system in use on a rotary kiln consists of an X-ray tube (right), a sample chamber (centre) and a CCD camera (left). © Copyright H.C. Starck GmbH

«information from practice»

New developments for correct thickness measurements on microscopic structures

Figure 1: Example of small structures on wafers. Solder bumps about 30 μm thick and 30 μm in diameter consist of a base of Cu with a 10 - 15 μm thick pad of SnAg on top. The image was generated using confocal microscopy.

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In the semiconductor industry and electronic components in general, the structures to be tested get smaller and smaller. The FISCHER XDV®-μ instruments give our customers the right tools to correctly measure the thickness of gold, nickel, tin, tin/silver, copper and other metallic layers on wafer pads, solder bumps or SMDs with a diameter of 30 μm. Reliable measurements on these small structures are only possible when several conditions are met. First, instrument device structure and table precision must be suitable to ensure a positioning accuracy of less than 1 micrometre. Second, only specifically suited X-ray optics that effectively focus all of the beam on the measurement area can be used. Third, suitably optimised software for adjustment and evaluation is required.

FISCHERSCOPE®

Halo effect

Figure 2a: Example of a

Figure 4a: SEM image of a

scan with Sn-K over the

wafer with Sn pads 40 μm

edge of a foil. The curve of

thick. The thickness of the

the measurement points

Sn layer on each pad was

indicates a significant

measured with capillary

halo effect.

types A and C.

(capillary A)

Figure 2b: Example of a scan with Sn-K over the edge of a foil. The curve of the measurement points no halo effect. (capillary C)

The following discussion mainly addresses the properties and characterisation of the X-ray optics. Polycapillary lenses composed of several hundred thousand glass capillaries of micrometre dimensions are shaped with a specific geometry according to the tasks they must perform. X-rays from the tube are guided through the glass capillaries by total internal reflection and focused on the specimen. However, X-ray reflection depends on the energy of the X-ray quanta and the reflective material. The shorter the wavelength of the radiation, the smaller the total reflection angle. At an energy of 20 keV, the angle is approximately 0.1° with normal window glass. To obtain proper focusing of the X-rays, the bottom ends of the glass capillaries must be aimed as accurately as possible at the same small point. This requires bending them with the right radius. Under these conditions, X-rays with energy greater than 20 keV can strike the sample “unfocused”. This unwanted side effect, which is called a “halo”, previously prevented the reliable analysis of microscopic structures with spectral energy levels

The proportions of the focused and unfocused X-ray radiation can be determined by integrating the calculated and measured intensities. In the chart in Figure 3 it can be seen that with capillary C over 98% of the intensity lies within 50 μm on the specimen, compared to less than 80% with capillary A. A significant fraction of the radiation from capillary A falls in areas that are several hundred micrometres outside the actual focus spot. The effect of this can be illustrated using a typical example from the semiconductor industry. On a wafer there are pads of several sizes (50 μm, 75 μm and 100 μm) coated with tin (Figure 4a). The tin layers on the various pad sizes are measured using both sorts of polycapillary optics. It is clear that when the capillaries with halo Measured thickness of Sn on pads (with/without halo)

1.0

Relative thickness of Sn layer (µm)

indicates X-ray optics with

0.9 0.8 0.7

Relative thickness of Sn layer

0

25

50

75

100

Pad measurement (µm)

Figure 4b: Comparison of the results of measuring Sn thickness on pads of Figure 3: Intensity distribu-

different sizes with the two capillary types. Using the polycapillary (with halo)

tions calculated from

one obtains a smaller result for the thickness (normalised to the value of the

the foil scans for the two

halo-free capillary). On smaller pads the loss is even greater.

capillary types in Figures 2a and 2b. For capillary A, about 80% of the intensity is within 50 μm; the remainder is spread out

are used, the measured coating thickness is approximately 20% less because roughly 20% of the radiation lands outside the pads on the specimen. The smaller the pad, the stronger the effect, as can be seen from Figure 4b.

over a large halo. For capillary C, approximately 98% of the intensity is within 50 μm.

above 20 keV, such as the Sn-K line at 25 keV. IfG in Berlin has now succeeded in producing halo-free capillaries. Their properties and potential uses are briefly described below.

With this innovation, IfG and FISCHER have together managed to develop the first polycapillary optics optimally suited to the analysis of microscopic structures. It will be used as standard in FISCHER’s XDV®-μ devices for wafer analysis. Marcel Bermekamp, MSc Physics Dr Wolfgang Klöck

Polycapillary optics can be characterised by an intensity scan over the edge of a metal foil, in this case tin (Sn-K line). The steeper the intensity distribution, the better the focusing of the polycapillary optics. The two figures below illustrate the difference between polycapillary optics with and without halo.

FISCHERSCOPE®

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«closer examination»

New SIGMASCOPE® SMP350 conductivity meter Checking for mix-ups from automotive suppliers Vehicle parts must be tested for crash strength. Unfavourable changes to the material properties occur when the heat treatment has been incorrectly applied. Aluminium alloys with various hardness grades resulting from different heat treatments are tested, since only artificially aged profiles may be used for further processing. Vehicle manufacturers need a test for this to ensure that no mix-ups have occurred.

Figure 1: The new SIGMASCOPE® SMP350 with high-resolution touchscreen

Figure 2: A technician uses the SIGMASCOPE® SMP350 to check material

display interface.

properties on an airplane.

The electrical conductivity of non-magnetic metals is an important material property that provides information about how well a metal conducts electricity as well as indirect information about its composition, microstructure or mechanical properties. The SIGMASCOPE® SMP350 measures specific electric conductivity using the phase-sensitive eddy current method as described in EN 2004-1 and ASTM E 1004. The signal processing technique enable contactless measurement of conductivity even under a paint or plastic coating up to 700 μm thick. This instrument is used in numerous applications.

Probes All probe types with multiple frequencies in the range of 15 kHz to 2 MHz are suitable for use in these applications. All probes can be connected to the same type of device.

Aircraft industry Testing is carried out to determine whether aluminium alloys have been overheated during milling. Before a part is released for series production, the conductivity of a preproduction part is fully tested. This assesses the requirements for the material properties. Because material properties can change while the aircraft is in service, cells are checked periodically.

1 2 3 4 … 10 Average Standard deviation

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σ (MS/m) 22.46 22.53 22.56 22.54 … 22.46 22.52 0.04

Table 1: Measurements of aircraft-grade aluminium with the SIGMASCOPE® SMP350 and the FS40 probe. The electrical

The FS40 probes are proven for the aircraft industry. Among other things, they can be used to test for heat damage and material fatigue. The newly developed FS40HF probe is a high-frequency probe for near-surface measurements. It is particularly suitable for testing thin sheet metal and layers, as well as thermally sprayed coatings. The new FS40LF is a low-frequency probe suitable for measurements on thick sheet metal as well as for material testing in coin production. A thermal sensor – either the integrated or optionally available external one – makes it possible to measure ambient or sample temperature. The temperature effect on conductivity is compensated automatically to avoid incorrect measurements. Standards for calibrating the instrument are necessary because comparative measurements are performed with the eddy current method. Certified standards are available for the entire conductivity range. For the aircraft industry, FISCHER is the exclusive supplier of conductivity standards traceable to Boeing.

conductivity of aircraft aluminium is typically 19 – 24 MS/m.

Dr Sebastian Zaum

FISCHERSCOPE®

«information from practice»

Quality service – the key to long-term customer satisfaction

FISCHER instruments are known for their outstanding precision and long life. Two factors are crucial for this: instruments of the highest quality and outstanding service. Therefore, excellent service is an essential factor for determining whether or not an instrument can deliver full performance over its entire service life. High-quality service can only be guaranteed by a highly-trained service team. At FISCHER, our worldwide presence and broad product portfolio make especially high demands on the service organisation. That is why we give high priority to the regular sharing of knowledge within the service organisation. Our service training courses provide the right tools to achieve this goal. There are more than 90 dedicated service technicians worldwide ready to assist our customers. The service training programme keeps our employees trained and up-to-date at all times, therefore

ensuring outstanding expertise in the global service team. This enables FISCHER to offer expert service and numerous service products locally in all sales regions; these include: • Service and maintenance agreements with yearly upkeep • Preventive maintenance • Repairs • Calibration Due to their high precision, FISCHER instruments are often used to test critical quantities. It is therefore crucial that our instruments are ready for use again as quickly as possible should a repair be needed. For this reason, we keep on stock in our worldwide branches key spare parts that are essential for operation, so they can be delivered promptly. The benefits of our service organisation are obvious: worldwide service expertise and trusted support, quick response times due to local presence, support in local languages and familiarity with local circumstances. That is because our sole objective is to create clear added value for our customers through outstanding service quality.

www.helmut-fischer.com

FISCHERSCOPE®

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