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Industrial-scale inkjet printed electronics manufacturing—production up-scaling from concept
tools to a roll-to-roll pilot line
View the table of contents for this issue, or go to the journal homepage for more
2014 Transl. Mater. Res. 1 015002
(http://iopscience.iop.org/2053-1613/1/1/015002)
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Industrial-scale inkjet printed electronics manufacturing—production up-scaling from concept tools to a roll-to-roll pilot line
Robert Abbel1, Pit Teunissen1, Eric Rubingh1, Tim van Lammeren1, Romain Cauchois1, Marcel Everaars2, Joost Valeton3, Sjoerd van de Geijn2 and Pim Groen1,4
1 Holst Centre—TNO, High Tech Campus 31, 5656 AE Eindhoven, The Netherlands2 SPGPrints b.v., Raamstraat 1–3, 5831 AT Boxmeer, The Netherlands3 Roth & Rau b.v., Luchthavenweg 10, 5657 EB, Eindhoven, The Netherlands4 Faculty of Aerospace Engineering, Delft University of Technology, Kluyverweg 1, 2629 HS Delft, The Netherlands
E-mail: [email protected]
Received 7 March 2014, revised 13 May 2014Accepted for publication 21 May 2014Published 4 July 2014
Translational Materials Research 1 (2014) 015002
doi:10.1088/2053-1613/1/1/015002
AbstractAn efficient strategy for the up-scaling of processing technology for inkjet printing of silver nanoparticle inks towards industrially relevant manufacturing volumes is described. This has been demonstrated by the roll-to-roll production of fine conductive patterns on polymer foils. Starting with small-scale benchmarking to identify the most suitable ink–substrate combination from a range of commercial products, the processing conditions for inkjet printing and sintering were continuously optimized during three consecutive stages. During each iteration, the scale of the experiments in terms of complexity, time requirement and materials usage was increased, thereby more closely resembling the final industrial-scale production conditions. This increased effort was, however, counterbalanced by limiting the number of necessary experiments by purposeful selection based on the results obtained at the lower levels. In addition, the outcome of each previous iteration round served as a starting point for the optimization during the next higher stage. In this way, it was possible to strongly restrict the number of experiments to obtain valuable information about the most ideal conditions at the final stage, which was a roll-to-roll pilot production line. Following this approach, large-area functional conductive structures on plastic foils could be prepared in a continuous manner at process speeds of up to 10 m min–1. These samples showed promising properties for application in printed electronic devices.
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Keywords: printed electronics, inkjet printing, silver inks, photonic sintering, roll-to-roll processing
S Online supplementary data available from stacks.iop.org/TMR/1/015002/mmedia
1. Introduction
Efficient strategies for the up-scaling of production processes from the research laboratory to volumes relevant for industrial applications are key to any innovative manufacturing technol-ogy’s commercial success. Although this is a general challenge in terms of materials cost, time and labour, it is especially relevant when the used starting materials are expensive. A strik-ing example is the processing of noble metal based inks for the printed electronics industry [1], as is necessary for devices such as RFID antennas [2–4], touch panels [5], electrochromic devices [6], organic light emitting diodes [7] or photovoltaic cells [8–10]. In all these examples, well-defined conductive structures with high resolutions must be achieved to allow efficient device performance. Typically, line widths and spacings well below 100 microns are desired [11], although the exact technical requirements may vary depending on the exact application. The functionality of printed electronics devices is also extremely sensitive to printing defects such as undesired discontinuities and connections [12], which results in a much increased need for high reliability printing compared to the graphics industry. Further critical parameters are the structural topology (layer height and surface roughness [13]), the adhesion of the metallic tracks to the substrate material [14], and of course the electrical conductivity. To comply with all these requirements, a careful choice of suited ink–substrate combinations and a thorough optimization of the processing conditions are necessary.
A number of deposition techniques for metallic inks are available, such as spray [15] and slot die coating [16], and various printing methods like screen [2, 4], flexo [6], gravure [17, 18], and inkjet [4, 7, 8] printing. In cases where a homogeneous unstructured metal layer is needed, e.g. for non-transparent back electrodes of OLED and OPV devices, coating technologies can be used, but they fail when more complex functional structures are required. The choice for a certain printing method to deposit conductive patterns is highly dependent on the exact technical and commercial boundary conditions for the specific product. Generally, for industrial large- scale manufacturing, continuous processing is advantageous, i.e. roll-to-roll (R2R) processes are strongly preferred over sheet-to-sheet (S2S) production [9, 10, 17, 19–25]. Rotary screen printing of metal pastes is a mature and well established high volume technology, but the rather high layer thicknesses and surface roughnesses provided by it can pose serious restrictions to the compatibility with a number of device architectures [13]. Also, most commercial metal pastes are based on micron-sized metal flakes rather than nanoparticles [3], which limits the final spe-cific conductivities unless harsh post-deposition processing conditions are applied, which tend to be incompatible with most low cost substrates. Flexo and gravure printing of metal inks are also R2R compatible and have been demonstrated to provide excellent narrow line widths in the range of 10 microns and below in combination with good conductivities [6, 17, 18]. Changing the desired printed structures, however, requires the acquisition of dedicated rotary screens or plate cylinders for each individual pattern, which can amount to a substantial financial invest-ment, especially when small sample numbers are desired. In this respect, inkjet printing can be a highly interesting alternative, as a virtually unlimited variation of the produced structures is
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possible by simply adjusting the digital image input. In addition, being the only non-contact printing technology, inkjet printing also allows the deposition of materials on mechanically highly sensitive substrates [26, 27].
A similar choice as for the printing technologies needs to be made with regard to the post-dep-osition treatment, which is necessary to render the printed inks conductive by removal of organic components (solvents, stabilisers, etc) and sintering of the particles [28]. Although a number of techniques have been reported in the scientific literature, including exposure to chemicals [29, 30], microwave [31] and infrared [16, 32] radiation, laser beams [33], electrical currents [34], or plasmas [35], at present only two have been developed to such an extent as to be of interest for large-volume industrial R2R processing. The traditional approach of thermal drying and sinter-ing using hot air ovens is technically easy to achieve, but the maximum temperatures are limited by the thermal stability of the plastic substrates, and as a consequence, the process is generally slow and inefficient in terms of energy consumption. Recently, photonic flash sintering has been introduced as a promising alternative [36–41]. It relies on the localized heating of the ink by selective absorption of visible light, and allows high peak temperatures and fast, efficient pro-cessing by exposure to very short, but highly intense flashes.
Even when a certain combination of technologies has been chosen for the manufacturing of fine conductive lines, much optimization work still needs to be done before the approach is ready for application in an industrial production environment. Optimizing the conditions for noble metal ink printing and post-deposition treatment immediately on a large R2R scale would, however, necessarily take a long time and additionally require huge amounts of expensive inks to be wasted in the process. The search for appropriate materials and processing conditions is therefore usually carried out on a small scale. When following this approach, one is, however, frequently confronted with the problem that the conditions applied on laboratory equipment are not directly comparable to those present in an industrial production facility. Strategies must therefore be developed that allow the reliable transfer of optimized processing conditions from the laboratory to large-scale manufacturing [25].
In this contribution, we report on our research activities to develop an efficient approach for the production of highly conductive fine silver patterns on plastic foils for printed electronics applications by a combination of inkjet printing and photonic flash sintering. The core idea is to divide the scale-up process into different stages of increasing complexity, which overlap suffi-ciently, so that the outcome of one level of experimentation can be reliably used as starting point for the next higher stage. During each stage, the specific challenges of large-scale inkjet printing (e.g. control over ink–substrate interactions, reliable and stable droplet ejection from hundreds of nozzles simultaneously, accurate print head alignment), and photonic flash sintering are dealt with on an increasing scale. On the one hand, this strategy allows us to acquire reliable informa-tion on the processing conditions relevant to R2R processing, while at the same time limiting both materials consumption and time investment. Following this approach, we have been able to demonstrate process condition optimization on a pre-industrial R2R production line operating continuously at speeds of up to 10 m min‒1.
2. General strategy
For both inkjet printing and photonic flash sintering, process optimization from small scale to pre-industrial R2R production has been subdivided into three individual steps. Starting with rather basic printing and sintering equipment, a large number of commercial conductive silver
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inks could be screened and compared within a rather short time and using very limited volumes of sample material (generally in the order of 5 ml). After one candidate ink had been selected based on this benchmark procedure, both its printing and photonic sintering conditions were optimized, still using the basic tools and limiting the sample geometry to simple straight lines. In a second step, the results from this optimization process served as a starting point for testing the ink’s performance on a larger scale, requiring ink volumes of about 100 ml, but also allowing the processing of complex samples up to a size of 30 × 30 cm2. Several different industrial inkjet print heads and photonic S2S sintering equipment were used at this stage. Again, the outcome obtained during these tests was used as the input for the final iteration round, during which the production scale was increased towards pre-industrial R2R processing. For this purpose, an R2R pilot line was designed and constructed, comprising an industrial inkjet printer, including a recirculation system to prevent sedimentation, agglomeration and nozzle clogging over longer times, and an R2R-compatible photonic sintering tool. Ink volumes necessary during this step were in the order of 1 litre, and the sample size in this case was essentially limited only by the length of the substrates. The entire optimization strategy is schematically depicted in figure 1, as well as the specific equipment used at each stage and representative samples. Figure 2 shows a complete overview of the R2R pilot production line.
Figure 1. Schematic representation of the general approach presented in this study, and photographs showing the equipment used and typical samples.
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3. Ink selection
As there are a vast number of commercially available conductive inks on the market and their number is continuously growing, the first step was to identify the product with the best overall performance. To that end, sample amounts of a total of 15 commercial inkjet inks (all of them based on concentrated silver nanoparticle dispersions) were subjected to a standardized bench-marking procedure, which involved as a first step characterizing their inkjetting performance on a standard materials printer, using inexpensive and disposable cartridges with small ink vol-umes. Next to be tested were the interactions with a number of substrates relevant for printed electronics applications and the ink’s sintering behaviour under thermal and photonic flash treat-ment. Exemplary for the entire database collected during these testing activities, the characteris-tics and key results of three different products are presented here (table 1, figure 3; see also the supplementary information available at stacks.iop.org/TMR/1/015002/mmedia).
After filtration in order to remove larger particles and aggregates, the printing behaviour of the inks was evaluated. Starting with a standard waveform, this was varied to achieve optimal jetting behaviour in terms of jet straightness, absence of satellite droplets and nozzle stability.
Figure 2. The roll-to-roll pilot line used in this study.
Figure 3. Summarized behaviour of ink 1. Jetting behaviour using an optimized wave-form (a), micrographs of printed and sintered lines (1 pixel) on two types of substrate (b), spreading behaviour for lines of different widths on a number of relevant substrates (c). See the supplementary information (available at stacks.iop.org/TMR/1/015002/media) for the complete data for all three inks.
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Depending on the envisioned application, conductive inks need to be printed on different substrates with vastly varying surface properties. Therefore, it is not expected that one single ink will show optimal performance on each type of substrate; rather, what is sought is an ink with acceptable wetting, spreading and adhesion behaviour on most of the substrates under consideration. The tests were performed on two inorganic surfaces and three polymeric foils (see the supplementary information). A set of lines with different nominal widths were printed on the substrates, sintered thermally, and their deviations from the predetermined values were measured by optical microscopy. In addition to the actual line width, the adhesion of the sin-tered silver structures is another important characteristic of the ink–substrate interactions. It was tested for all samples using the tape removal method and a qualitative estimation of the amount of removed material (see the supplementary information).
In order to render the printed inks functional, i.e. dry and conductive, thermal sintering at two different temperatures was applied. Interestingly, two inks showed worse conductive behaviour at higher temperatures, which might be due to more intense crack formation under harsher treatment, as is also evident from the optical microscopic images (see the supplementary infor-mation). Although thermal sintering is technically very simple, it is not very practical from a perspective of large-scale R2R processing and energy efficiency, due to the long sintering times required and therefore slow process speeds. As a much faster and more efficient alternative, pho-tonic flash was applied to the three tested inks (table 1, figure 4(a), supplementary information). Figure 4(b) shows the resistance decrease as a function of time during flash exposure for lines of ink 1 with fixed lengths and varying widths. It is evident that broader lines show faster sintering, which is most probably due to the higher temperatures achieved, since their relative contact area with the substrate is lower, slowing down heat flow out of the ink.
Table 1. Summarized characteristics and test results of three commercial conductive silver nanoparticle inks.
Ink 1 Ink 2 Ink 3
SunTronic U5603 UTDot UTDAg25 Ulvac L-Ag1TeH
General characteristicsa
Silver load (wt%) 20–30 20–30 50–60Average particle size (nm) 30–50 < 10 < 10Solvent system Mixture of
alcoholsHydrocarbon mixture
Aromatic hydrocarbons
Viscosity (mPas) 10–15 1–10 10–15
Printing behaviourPlate wetting None Weak StrongJetting behaviour Well-defined Acceptable AcceptableNozzle stability Good Acceptable Low
Sintering behaviour30 min at 130 °C on PEN (% bulk Ag conductivity)
10.1 ± 3.6 18.8 ± 10.6 11.3 ± 6.4
30 min at 150 °C on glass (% bulk Ag conductivity)
10.8 ± 1.9 No conductivity 5.9 ± 4.8
Flash sintering single pulse, 10 Hz, 600 W (time scale, % bulk Ag conductivity)
1–5 s 11.9 ± 3.8 Very limited foil deformation
No conductivity within 60 s
4–8 s extreme foil deformation, no conductivity determined
a Information about the composition and physical properties of the inks has been provided by the suppliers.
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Based on the test results described, it becomes obvious that no ink showed supreme per-formance over the respective competitor products on all aspects of the benchmark study. Nevertheless, ink 1 clearly stood out on a number of important characteristics, such as its very favourable printing behaviour and the advantageous interactions with most tested substrates (with the noticeable exception of ITO). Adhesion on glass was problematic for all three inks under investigation. Although ink 1 does not give the best conductivities under the thermal sintering conditions applied in this study, it is most stable towards temperature variation, and, more importantly, responds very positively to photonic flash treatment in terms of process speed, final conductivity and substrate stability. It was therefore chosen as the reference material for the optimization on a larger scale, although under certain specific conditions, notably on ITO substrates, other types of inks will definitely be preferred.
Photonic sintering was optimized using only the best performing product (ink 1) on PEN foil. In contrast to thermal sintering, a lot of variables need to be scanned with photonic sin-tering, such as flash intensity and frequency, pulse length and the exact flashing pattern (e.g. single pulse vs sequenced flashing). In order to limit the number of measurements, an experi-mental approach was followed in which frequency, intensity and the number of pulses per burst were systematically varied. The results are summarized in the contour plots in figure 4(c). Exactly in line with expectation, increasing the intensity, frequency or number of pulses gives rise to lower final resistances. At the same time, significant foil deformation was observed when the thermal load became too high due to extensive flashing. Generally, it was found that substrate damage was stronger in broader lines, which is consistent with the earlier mentioned
Figure 4. Photonic sintering optimization. Optical micrographs of lines of three dif-ferent conductive inks on PEN (nominal width 1 pixel) after having been subjected to identical flash sintering conditions (a). Flash sintering behaviour (electrical resistance vs time) for lines of ink 1 of different widths (60% intensity, 10 Hz flashing frequency, 5 ms pulse length) (b). Contour plots of the sintering behaviour of ink 1 for different numbers of pulses (c).
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assumption that cooling by heat transfer into the underlying foil becomes the more restricted the broader the structure.
4. S2S process optimization
Following the reasoning described in the section above, ink 1 was chosen as the only ink to work on a larger scale. Also, PEN was used as the substrate of choice for these tests, in order to keep the number of experiments limited. For the S2S optimization of the printing process, an inkjet printer that could be equipped with several industrial inkjet heads was used, allowing us to choose the best performing product for integration into the R2R setup at a later stage.
As in the case of the small-scale printing optimization, parallel lines printed in the movement direction of the printing head were chosen to start with. Varying the resolution at different nomi-nal line widths revealed structures ranging from lines of isolated droplets (resolution too low for the droplets to flow together on the substrate) to lines that were locally deformed by bulging (wet ink lines too high to remain stable). At intermediate resolutions, very well-defined straight lines were obtained (figure 5(a)).
Printing lines in the orthogonal direction of the print head movement proved much more chal-lenging, due to problems resulting from satellite formation and insufficient synchronization of the droplet ejection. Whereas it can be assumed that the satellites are also formed when printing lines parallel to the head movement direction, they will not be evident on the printed structures, since they are expected to land on places where ink needs to be printed anyway. This is different when the line and the print head do not run parallel. As can be seen in figure 5(b), it was pos-sible to solve these problems by adjusting the droplet ejection waveform, although the resulting line definition was still worse than when printing parallel to the head movement. The remaining irregularities were mainly due to insufficient synchronization of the nozzle activity and could be largely solved by correct timing of the droplet ejection. A similar evaluation study was car-ried out for another type of industrial inkjet print head to determine which product to choose for integration in the R2R unit (vide infra).
The photonic sintering process was optimized using a number of sample lines of different widths printed on PEN foil under the optimized conditions derived from the procedure above. Whereas in the small-scale processing, the samples had been stationary lines placed in the focus of an elliptic reflector, now the R2R process was mimicked in a more realistic way: an S2S photonic sintering tool was constructed, which allows us to transport samples of printed con-ductive inks on substrates up to a size of 30 × 30 cm2 underneath a set of two different xenon flash lamps at a predefined speed by means of a moving samples holder (figure 1). One lamp is able to give highly energetic flashes, but at low frequency, whereas the other one can flash at high frequencies, but with relatively low intensities. There is also the possibility to arrange two lamps opposite to each other, in such a way that top, bottom or double sided illumination can be investigated. In this way, various substrate speeds, illumination modes and flashing parameters could be investigated and optimized with respect to foil deformation and final conductivity. In addition, the combination of the two different lamps was tested. The final result for photonic sintering conditions optimized with respect to sintering speed, final conductivity and substrate stability is shown in figure 5(c) and compared to thermal sintering. For an example where we have demonstrated the functionality of the resulting silver structures in printed electronics dem-onstrators, the reader is referred to [8].
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5. R2R process optimization
For further up-scaling of the production process, one needs to make the transition from batch-wise S2S manufacturing towards continuous R2R production. For this purpose, an industrial-scale inkjet printer equipped with industrial print heads was combined with an R2R compatible photonic flash sintering unit on a pre-pilot line (figures 1 and 2). The flash unit principle is based on the S2S design, but now the foil can be transported through the focus line in a continuous manner. Also, more flash lamps and an infrared unit for drying were installed to allow higher processing speeds than in the S2S tool (see the supplementary information).
Similar experiments as described in the S2S optimization part were also conducted on the R2R printing and sintering line, starting with the optimized output from the S2S experiments as the baseline conditions. Printing of ink 1 on the PEN substrate was optimized for lines parallel to the printing (i.e. web movement) direction by varying drop size and resolution. Whereas no continuous lines were obtained for the smallest droplet volumes at the lowest resolution, depos-iting more ink gave rise to very well defined single pixel lines, ranging in width from below 50 to almost 200 microns (figure 6(a)). In analogy to the earlier S2S experiments, printing lines orthogonal to the foil movement direction proved much more challenging, due to higher inac-curacy of the droplet placement. Satellite formation, however, could be ruled out by applying the optimized waveform settings developed using the S2S testing equipment. As at the current state, only one print head has been installed and thus the resolution was fixed at the native resolution
Figure 5. S2S process optimization. Optical micrographs of single pixel lines of ink 1 on PEN printed parallel to the inkjet head movement direction with different resolutions (a). Optical micrographs illustrating different stages of the printing optimization for test patterns of ink 1 on PEN printed orthogonal to the inkjet head movement (b). Electrical conductivity of ink 1 lines of different widths on PEN for thermal sintering (130 oC for 30 min) and optimized photonic sintering (c).
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of the head (360 dpi), varying the droplet size was the only viable option to achieve continuous lines in that direction. As can be seen in figure 6(b), only the largest droplet size gave rise to continuous structures. Stacking a number of print heads next to each other could, however, result in higher flexibility and more control of the pattern formation.
Optimizing the sintering conditions was carried out by first separately studying the drying and sintering processes (using the infrared and Xe flash lamps, respectively; see the supple-mentary information). Although heating by IR illumination already gave reasonable conduc-tivities, exclusive flashing with visible light proved more efficient in terms of final conductivity (figure 6(d)). After process optimization for both treatment methods (mainly intensity vari-ation, but also frequency variation for the flash lamps), IR treatment alone gave 5–7% bulk silver conductivity, whereas Xe flashing alone resulted in values around 8–9%. Applying these optimized conditions in combination resulted in too much heat development during the sin-tering process, and the samples treated that way suffered from severe substrate deformation. However, very advantageous sintering behaviour for the combined treatment could be reached
Figure 6. R2R process optimization. Optical micrographs of single pixel lines of ink 1 on PEN printed parallel (a) and orthogonal (b) to the substrate movement direction. Line width as a function of drop size for single pixel lines of ink 1 on PEN for different reso-lutions (c). Final electrical conductivities after process condition optimization for R2R printed and sintered ink 1 on PEN for infrared, visible flash and combined illumination (d). For process details the reader is referred to the supplementary information (available at stacks.iop.org/TMR/1/015002/mmedia).
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by lowering the intensities for both IR and visible illumination, resulting in conductivities around 12% bulk silver, which was impossible to achieve by either of the techniques separately (figure 6(d)). At a surface coverage of 5% and a line height of 1 µm, this material would result in a sheet resistance of 2.5 Ω sq‒1, which is significantly lower than the value of typical ITO coatings, while decreasing the total transparency by a factor of 0.05. S2S inkjet printed current shunt line patterns and collecting grids with similar line shapes and conductivities have already been previously demonstrated to significantly enhance the performance of OLED devices [7] and organic photovoltaic cells [8]. For types of application other than transparent electrodes—where higher total conductances are needed (e.g. in RFID antennas)—thicker layers might be necessary, which could be achieved by multiple layer printing, wider structures, or by increas-ing the resolution (and thus droplet density) in the printing direction. When increasing the web speed, the intensity obviously needed to be adjusted to compensate for the reduced exposure time of the ink samples to the flash illumination. Repeated runs using optimized conditions have shown that they allow the stable and reproducible production of well-defined conductive silver structures at processing speeds of up to 10 m min‒1. At even higher substrate speeds, irreproducible sintering behaviour and uncontrolled foil deformation were observed, possibly because in those cases the flashing frequency was not sufficiently high to allow homogenous illumination of the entire sample surface.
6. Summary, conclusions and outlook
Industrial processing technologies for conductive inks can be efficiently established by adopting a stepwise approach of continuously increasing the scale and complexity of the experiments, while at the same time purposefully narrowing down their number. Starting with rather simple and small-scale tests on laboratory equipment, screening and benchmarking of a vast number of products can be carried out with limited investments of time and materials. In this way, it is possible to identify the most promising candidate materials that best fulfil the specifications for a certain application. The search for optimal processing conditions can be conducted in a rather straightforward manner, also starting at a small scale, and using the outcome of these experi-ments as the input and starting point for further optimization at a higher level. At this intermedi-ate stage, the scope of the experiments in terms of complexity, materials use and time investment is enlarged, thereby more closely resembling the ultimate manufacturing process and allowing one to get more meaningful insights. This is compensated for, however, by the fact that the number of necessary experiments can be significantly limited as a consequence of information gained from and choices made at earlier stages. Depending on the complexity of the envisioned final application, several such consecutive iteration steps might be necessary to achieve the most efficient process optimization strategy. Following this approach, we have succeeded in establish-ing an R2R process for the production of electrically conductive patterns on plastic foils using inkjet printing and photonic sintering of a commercial silver nanoparticle ink. Applying opti-mized processing conditions derived from experiments on a smaller scale, functional structures were produced at web speeds up to 10 m min‒1 that show promising materials properties for application in a number of printed electronic devices.
At the current state, the developed concepts, processes and tools are used to support ink manufacturers, printing companies and the suppliers of drying, curing and sintering equipment in their own R&D activities. Collaborations with universities and research institutes are also
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ongoing. A core challenge for future work is to move the status of the technology forward from the current demonstration status towards implementation in a production environment, where it will need to prove its economic profitability. This includes an upgrade of the printers to a larger number of inkjet heads in order to achieve larger widths of the print area, as well as increasing the number of flash lamps in the sintering unit to allow for higher processing speeds. Together with its industrial partners, the Holst Centre is currently working on these tasks, as well as on the commercialization of individual components, such as the S2S and R2R photonic flash sinter-ing units. Concrete actions to achieve the latter goal are a reduction of the cost price in order to make it more attractive for printed electronics manufacturers to replace their hot air treatment machinery with photonic sintering equipment.
Acknowledgements
This work has been financially supported by the European Commission within the Framework FP7-ICT (grant number ICT-2009.3.3, project number 248816, project acronym LOTUS), the Dutch Ministry of Economic Affairs and the Province of Northern Brabant.
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