Ceramic Tape-Based Meso Systems Technology

Abstract

Ceramic tape technology was initially developed for efficiently manufacturing interconnects and hybrid microelectronics circuitry through sequential printing and firing of conductor, resistor and/or dielectric paste formulations onto a substrate. Recently, it has been recognized that ceramic tapes can also be used as an efficient and convenient medium for the manufacturing of meso-scale electro-mechanical systems. In the green (pre-fired) state, the ceramic tapes consist of alumina particles, glass frit, and organic binder; and they are soft, pliable, and easily machinable. In each layer, one can machine flow conduits and mechanical devices and print electronic circuits. Very many layers can be stacked together to form complicated, three-dimensional, monolithic structures. These layers can be laminated and sintered. During the sintering process, the organic binder burns out, the glass flows, and the material hardens. It is possible to cast tapes of various ceramic composition to obtain desirable properties. The paper describes mechanical, chemical, and thermal machining of prefired Low Temperature Co-fired Ceramic Tapes (LTCC); the dimensional changes occurring during the lamination and sintering processes; the use of sacrificial layers to prevent the sagging of internal suspended structures during the lamination and firing processes; the bonding of tapes to alumina, silicon, glass, and metals to form a hybrid technology; and the manufacturing of microchannels and a flow sensor in ceramic tapes. Packaging is widely considered to be the Achilles heel of silicon-based MEMS technology since it is difficult to interface silicon MEMS devices with each other and fabricate relatively large, three-dimensional structures. Low Temperature Co-fired Ceramic Tapes (LTCC), the packaging material of choice in the electronics industry, hold the promise of alleviating some of these difficulties.

Three-dimensional low-temperature co-fired ceramic shells for miniature systems applications

“…The work carried out over the past five years at the University of Pennsylvania has demonstrated that ceramic tapes can also be used as an efficient and convenient medium for the manufacture of meso-scale (millimeter to centimeter size) integrated fluidic systems (Bau et al 1998, Espinoza-Vallejos andSantiago-Aviles 2000). In the green state, the LTCC tapes are very flexible and soft which makes it easy to machine them.…”

“…In order to make conduits of various shapes, milling is more versatile and avoids the step-pattern of punching. Using 125 µm and 250 µm diameter mill bits, holes and slots of arbitrary shape are milled in a single layer of LTCC tape using a computer numerically controlled (CNC) machine (Bau et al 1998, Kim et al 1999.…”

Continuous Flow Analytical Microsystems Based on Low-Temperature Co-Fired Ceramic Technology. Integrated Potentiometric Detection Based on Solvent Polymeric Ion-Selective Electrodes

“…In addition to the possibility of creating complex three-dimensional structures, LTCC devices, once fired, are thermally stable compared to silicon devices, which generally work best at or near room temperature, 22 °C. Moreover, LTCC devices have been shown to work at temperatures exceeding 150 °C . Another important advantage of the LTCC systems is that the devices are self-packaged; thus, there is no need to mount the completed device onto a substrate.…”