The development of processing systems for electronic and microsystem applications is driven by the constant need for higher performance at smaller sizes. Examples of these developments are components with thinner layers such as MLC:s or printed structure with higher resolution such as LTCC structures. There is also a trend towards use of nanosized powders as in SOFC technology and new ceramic materials such as lead-free piezoceramics. Common for these developments is the need to disperse ceramic powders at high solids contents while controlling the rheology of the suspension. The use of newer types of comb polymer dispersants has given ceramic processing a new tool that make s it possible to tailor the suspension properties to a greater extent than before. Combining these dispersants with new types of latex binders it has been possible to create new environmentally friendly tape casting systems that yields high quality tapes.
Screen printing on tape cast layer can be used in combination with lamination to build a whole range electronic of microsystem devices. Rheological characterization combined with wetting measurements has given us a new systematic way to study pastes for screen printing. Our studies have shown that the viscosity alone cannot be used to explain the behaviour of a screen printing paste. To better understand and develop prints with high resolution and reliable quality it is necessary to study the viscoelastic behaviour of the printing pastes.
Today, a wide range of manufacturing technology is available to produce optical micro and nanostructures, such as diffractive optics, refractive microlens arrays, photonic crystals, resonant grating filters, and nanoparticles. The technology is strongly driven by the needs of microelectronics. Very fine structures with less than 100 nm feature sizes can be realized. This is fine enough for applications in the visible and infrared region. However, this high-end equipment is not really made for optics. For the special needs of optics (accuracy, overlay, material, substrate thickness) the equipment has to be adapted. This makes the fabrication expensive. Therefore, research effort is also focused on flexible and low cost technology. Binary or multilevel elements with feature sizes of 500 nm are commercially available. Electron-beam writing is used for laboratory demonstrators with fine structures. For larger structures laser-beam writing is more suitable (less expensive). Analog structures are still highly challenging. Standard are microlenses, which have spherical or cylindrical surface. Also aspheric shapes are feasible. However, more general structures are difficult to be realized with optical quality.
We will present different examples (diffractive optics, photonic crystal waveguides and optical MEMS) for application wavelengths ranging from the nanometer to micrometer. Challenges and limitations due the miniaturization will be discussed.
Optical methods are increasingly used for measurement of surface texture, particularly for areal measurements where the optical methods are generally faster. A new Working Group under Technical Committee (TC) 213 in the International Organization for Standardization is addressing standardization issues for areal surface texture measurement and characterization and has formed a Project Team to address issues posed by the optical methods. In this paper, we review the different methods of measuring surface texture and we describe a classification scheme for them. We then highlight optical methods and describe some of their characteristics. We compare surface profiling results obtained with several optical methods with those obtained with the stylus method. For moderately rough surfaces (Ra ~ 500 nm) roughness measurements obtained with white light interferometric microscopy (IM), confocal microscopy, and the stylus method seem to provide close agreement on the same roughness samples. For surface roughness measurements in the 50 nm to 300 nm range of Ra, discrepancies between white-light interferometry and the stylus method are observed. In some cases the discrepancy is as large as 80 % of the value obtained with the stylus method. Reasons for this are suggested. By contrast, the results for phase shifting interferometry over its expected range of application (Ra about 150 nm) are essentially in good agreement with those of the stylus technique.
Microfluidic devices are mainly used within the life sciences or chemical analysis. Polymers are ideally suited for these applications due to their physical and chemical properties. The development of micofluidic devices and applications in this device has to be done with respect to the surface properties like roughness or surface energy of the fluidic channels. Especially rapid prototyping methods are leading to surfaces at the devices with uncommon and different behaviour in comparison to the products from the series production processes. In this report, we describe rapid low cost hot embossing technologies with respect to complete process chains to fabricate microstructured prototypes with an excellent and representative surface quality with high aspect ratio. As tools we are using soft tools like PDMS as well as hard tools made of metals or alloys. These methods enables cost effective structuring of technical polymers like polycarbonate or cycloolefin copolymer. The main advantage of these approaches are the availability of the geometry and the specific target material right from the start of the evaluation process of microfluidic devices. The processes described are able to rapid prototyping for the development and evaluation of different microfluidic devices. So the processes can be used for short time to market approaches of micro structured parts.
First, the status of the current research related to a potential application of Lab-on-a-Chip Microsystems in the field of cancer is reviewed and discussed. Then, we will briefly describe research works carried out in my research group and in collaborating laboratories. Our objective is to develop Lab-on-a-Chip analyzers, simple and autonomous, for cancer diagnostics and for monitoring of cancer therapy. The complete system will make use of disposable chip sensors of the size of a credit card and a control unit of the size of a book. The principle of sensors is based on the determination of the concentration of “cancer markers”, which are proteins and DNA fragments present in physiological fluids (blood, saliva…). Our approach is based on the separation of bio-molecules present in the solution by electro-chromatography, carried out in multiple microfluidic channels; this separation shall be coupled with nucleic acid hybridization reactions (DNA) or immunological reactions (proteins) in liquid phase or using appropriate ligands bound to the nano-structured separation matrix. The bio-molecules of interest are finally detected thanks to optical wave-guides integrated in the chip..
Miniaturization of parts and components plays an important role in today’s economy, enabling the design and production of new and highly sophisticated technology in various industrial fields such as medical, bio-chemistry, automotive and telecommunication. Nowadays, production technology faces the challenge to manufacture small components within tight tolerances yet economical in large lots. In order to successfully harness this task, separating processes have been fitted to suit the needs for micro mold manufacturing and were combined with a subsequent injection molding process to satisfy the need for large scale production with a vast variety of possible materials. Hereafter, the scope lies on the production technology for micro mold namely micro milling, micro EDM and micro laser ablation. Characteristics of each process are introduced and compared to each other concerning surface properties, achievable tolerances, potential for miniaturization, machinable scope of materials and manufacturing productivity.
This presentation reviews the various measurement methods that may be used to characterise piezoelectric thin and thick films for applications such as macro-scale and micro-scale actuators. Current methods include; polarisation loop analysis, interferometry, modified Berlincourt methods, Laser Intensity Modulation Method, residual stress based on wafer curvature, modulus via laser flash and indentation methods and nano-scale probes based on modified atomic force microscopy. The material structure is typically characterised using various imaging techniques such as Scanning Electron Microscopy, Transmission Electron Microscopy and optical microscopy. The functional and dielectric properties are often closely linked to the geometry and boundary effects imposed by the material systems. Examples here include the film/substrate interaction where the constraining substrate influences the electroactive response of the piezo thin film. This has the effect of reducing useful actuation. In cases such as these, it is necessary to develop new measurement methods and/or to carefully model the system to understand these interactions. The methods outlined in this talk will include some of the methods that are covered by International standards (typically suitable only for bulk materials), and the vast majority that are devoid of any standards but that require evaluation and validation on an international basis.
Nowadays several qualified technologies have been established for the manufacturing of precision parts and microstructured surfaces in the field of MEMS, e.g. lithography, etching, LIGA, laser beam, ion beam or electron beam machining. However, mechanical processes, e.g. diamond machining, engraving, forming and molding, play also a significant role for the generation of microstructured surfaces and the manufacture of microparts. In this keynote speech the state of the art of mechanical manufacturing methods for microparts and microstructures will be introduced and discussed. Particularly the potential of machining processes like turning, milling and drilling using monocrystallyne diamond tools, deterministic microgrinding and polishing processes for structured surfaces will be concluded. Applications of these methods for optical and mechanical parts will be illustrated . The presentation will also focus on the selection of materials, machining parameters, tool design and measuring techniques.
With the development of micro- and nanotechnological products such as sensors, MEMS/NEMS and their broad application in a variety of market segments new reliability issues will arise. The increasing interface to volume ratio in highly integrated systems and nanoparticle (or nanotube) filled materials and unsolved questions of size effects of nanomaterials are major challenges for experimental reliability evaluation.
The terms “microreliability” and “nanoreliability” characterize this new field within the micro-nano transition region. Advanced simulation tools, new test and characterization methods have to be combined with reliability and life-time estimation concepts taking into account local field measuring techniques and materials testing procedures on different levels.
The author will also present practical applications from the field of automotive sensors and MEMS applications and will show how combined simulation, testing, and crack, fatigue and creep failure avoidance strategies will lead to new solutions to improve reliability as life-time estimation in the micro-nano interface region.