4M Knowledge base - papers

The ceramics substrates microprocessing by high precision laser technologies for microsystems, microsensors and actuators applications

Dr. Dumitru Ulieru (a), Dr. Ileana Cernica (b)
(a) ROMES S.A., 126 A, Iancu Nicolae Str, 77190, Voluntari (Bucharest), Romania,
(b) IMT – Bucharest, 32B, Erou Iancu Nicolae Str., 77190, Voluntari (Bucharest), Romania

Abstract

Microsystems (MST) as MEMS, MOEMS, MCMs, microsensors and actuators uses the same techniques as microelectronics processing to create structural components that are essentially micronic or submicronic mechanical parts. These parts usually require high precision fabrication unless post-fabrication finishing. For various types of materials of which a great used for obtaining microsystems, micro and nanodevices the laser micro and nanoprocessing is the best solution for accuracy and roughness surface quality high precision technologies suitable for batch processing of ceramics and other MSN substrate materials.

  • High precision microdrilling of microvias and different microholes configurations.
    Technical features of microprocessing for microsystems application with RF MCM detailed presented in the paper as
    shown on more tables with analyze of answers of more kind of support materials at laser radiation. The authors present also the detailed results of microprocessing of microholes realized by different lasers radiation as UV, Nd:YAG and CO2 for microvias of higher layers count for high density circuits ( HDI ) connection microholes as blind, through tapered holes, circular a/o squared areas etc.

  • Microcutting and contouring processing by high precision laser technologies.
    On the paper are presented the experiments and results studies obtained by the authors on the basis of high precision laser for chips separation and / or singulation on ceramics wafer processed including as individual extraction possibility.
  • Surface patterning generation by laser microprocessing
    The fine pattern generation of metal or alloy films on ceramic substrates can be structured directly with the laser direct patterning process. Our novel technology applications unless chemicals can resolve this problem by offering structuring processing of sensors and sensors systems able to fulfill these requirements.
Submitted on May 20, 2008 - 08:26.

A Soft Lithography Process for Manufacture of Alumina Micro-Components

Zhigang Zhu, Xueyong Wei and Kyle Jiang
Centre for MicroEngineering and NanoTechnology, School of Engineering, The University of Birmingham, B15 2TT, UK

Abstract

This paper presents a soft lithography technique to fabricate alumina microcomponents. The process uses elastomer polydimethysiloxane (PDMS) and makes the green patterns in tact after demoulding. The five steps of the soft lithography process are: (I) fabricating thick SU-8 moulds using UV photolithography; (II) producing PDMS soft mould from the SU-8 masters; (III) making aqueous high solids loading alumina suspension; (IV) filling patterned PDMS moulds with the aqueous alumina suspension; (V) demoulding and sintering. The rheological properties (Zeta potential and viscosity) of aqueous alumina suspensions was characterized in relation with varying pH values and concentration of dispersant (D-3005). The optimal parameters of the alumina suspension for the mould filling have been achieved as pH value = 11; concentration of dispersant (D-3005) = 0.05 g/ml; amount of binder (B-1000+ B-1007) = 0.75%, the highest solid loading = 70 wt.%. After pressurised mould filling, the complete, dense and freestanding microcomponents have been achieved by using 70wt.% alumina suspension and optimum fabrication technique, while the overall shrinkage is found as ca. 22%.

Submitted on November 12, 2007 - 16:23.

categories

ceramics | elastomers

An Investigation on Development of MEMS in LTCC by Embossing Technique

D. Andrijasevic(a), W. Smetana(a), S. Zoppel(b), W. Brenner(a)
a: Institute of Sensor and Actuator Systems, Vienna University of Technology, 1040 Vienna, Austria
b: Forschungszentrum Mikrotechnik, Fachhochschule Vorarlberg, 6850 Dornbirn, Austria

The latest results achieved during the investigation of possibilities for producing MEMS in unfired green Low Temperature Cofired Ceramic (LTCC) by embossing technique are presented in this paper. Ceramic tapes in unfired state are subjected to compression by means of using tools specially designed and developed for this purpose. Structures obtained in this way demonstrate high repeatability and surface quality comparable with those gained by other techniques. In comparison with traditionally used laser cutting or injection moulding for ceramic processing, this technique offers better resolution and further miniaturisation, improved rigidity of small structures and possibility to profile the vertical walls in U- and V-shapes. The main focus of this paper will be on the optimisation of embossing parameters (embossing force, embossing time and temperature) in order to get repeatable and reliable results. Structures produced in this way could be successfully used in optical as well as in medical applications.

Submitted on November 12, 2007 - 16:23.

categories

ceramics | Hot/UV embossing

Dielectric properties of hydroxyapatite based ceramics

J.P. Gittings (1), C.R.Bowen (1), I.G.Turner (1), A.C.E.Dent, F.R.Baxter (1), (2) and J.B. Chaudhuri (2)

(1) Department of Mechanical Engineering, University of Bath,BATH, BA2 7AY.
(2) Department of Chemical Engineering, University of Bath,BATH, BA2 7AY.

Abstract

This paper studies the ac conductivity and permittivity of hydroxyapatite based ceramics (HA) at temperatures from room temperature to 1000ºC. HA ceramics were prepared either as dense ceramics or in porous form with interconnected porosity and were sintered in either air or water vapour. Samples were thermally cycled to examine the influence of surface adsorbed water on conductivity and permittivity. Surface bound water was thought to contribute to conductivity for both dense and porous materials at temperature below 200ºC. At temperatures below 700ºC the permittivity and ac conductivity of HA was also influenced by the degree of dehydration and thermal history. At higher temperatures (700-1000ºC), bulk ionic conduction was dominant and activation energies are in the range of ~2eV, indicating that hydroxyl ions are responsible for conductivity.

Submitted on July 30, 2008 - 12:13.

Direct manufacture of ceramic micro components with layered manufacturing methods

Per Johander (a) , Urban Harrysson (b) , Ulrike Kaufmann (c), H.-J. Ritzhaupt-Kleissl (c)

a IVF Industrial development and production, Argongatan 30, 431 53 Mölndal, Sweden
b Fcubic Argongatan 30, 431 53 Mölndal, Sweden
c Forschungszentrum Karlsruhe, Institute for Materials Research III

Abstract

Layered manufacturing has mainly been used for prototype manufacturing in product development. Direct manufacturing of small components is very favourable due to the scaling effect. The number of components that could be manufactured in one batch grows by the square if the size of the parts is reduced to half. The ceramic material used is yttrium-stabilised zirconium. The structural information is printed by ink jet in powder layers of only 80 μm thickness. The actual part creation is done in a subsequent heat treatment process where a development process takes place. This is an advantage as the machine speed could be increased considerably compared to other layer manufacturing principles. The parts manufactured are impregnated with epoxy and the material properties are comparable or better than injection molded parts. The other option is sintering of the parts to full density. The sintering process has been studied and the shrinkage and material properties evaluated. A cost analysis has been performed comparing direct manufacturing of small batches of components to plastic mouldinginjection.

Submitted on May 20, 2008 - 10:34.

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