One-step firing for electroded PZT thick films applied to MEMS

Abstract

Free-standing electroded piezoelectric thick-films are straightforwardly fabricated thanks to the association of the low-cost screen-printing technology to the sacrificial layer method. After subsequent printing and drying of a stack of sacrificial, Au, PZT and Au layers on an alumina substrate, the final firing is performed at 900 °C. Then, the partial or total releasing step of the Au/PZT/Au is achieved in a diluted acidic solution. Bridges (3.3 × 3.3 × 0.080 mm 3 ) and cantilevers (8 × 2 × 0.09 mm 3 ) are directly attached to the alumina substrate on top of which they are processed. Studies of the electromechanical behavior of these components show the influence of both the releasing and the densification processes on the piezoelectric properties of the final component. Cantilevers fabricated with this method exhibit favourable properties for sensing applications.

One step densification of printed multilayers by SPS: Towards new piezoelectric energy harvester MEMS

“…Because of the residual porosity observed in the fired PZT printed film due to the removal of the organic binder before the firing, improved densification can be obtained by adding an additional isostatic step before the firing (Debéda et al, 2005). Also, as shown in previous work, a better compacity of the PZT thick films fired at 900°C can be observed when the PZT powder is mixed with the eutectic phase LBCu instead of the borosilicate glasses (Debéda et al, 2015).…”

Key features in the development of unimorph stainless steel cantilever with screen‐printed PZT dedicated to energy harvesting applications

“…PZT powder is mixed with three oxides (1%wt CuO, 0.8%wt Li 2 CO 3 , and 1.2%wt Bi 2 O 3 noted LBCu) expected to melt near 600°C and then (thus?) improve PZT densification 31 . After a milling step in order to eliminate agglomerates, the grain sizes of CuO, Li 2 CO 3 , and Bi 2 O 3 powders are 5 µm ± 0.03, 19 µm ± 0.11, and 6 µm ± 0.03 respectively.…”

“…A slow drying rate 1°C/min until 120°C is preferred for thick layers (>100 µm) to avoid cracks. The stacked printed layers are first isostatically pressed 5 minutes at 40 MPa and 65°C in order to improve the PZT densification 31 . Printed piezoelectric disks and cantilevers, as well as the ceramics, are then sintered 2 hours at 900°C using the same firing for the sake of properties comparison (Figure 4).…”

Improved manufacturing process for printed cantilevers by using water removable sacrificial substrate

“…This latter material was removed in an acetone bath to release a switch made by inkjet printing. Another used sacrificial layer has been a strontium carbonate (SrCO 3 ) in an epoxytype ink which is dissolved by immersing the structure in a weak acidic solution [11,12]. Nathalie Serra et al [6,13] employed a solution based on trimethylolethane removed by thermal treatment to develop bridges and cantilevers by screen printing.…”

“…Wei et al [17][18][19][20][21] fabricated piezoelectric cantilevers on cotton by screen printing. Alumina substrate has been chosen to manufacture suspended structures for several authors [6,12,13,[22][23][24]. A few examples can also be found using plastic surfaces: a microelectromechamical switch developed on polyimide substrate by lamination techniques [25,26], switches on Kapton polyimide [15], electrostatic microactuators made of a flexible sheet [27], or printed bridges on polyethylene terephthalate (PET) [14] or a cantilever also developed on PET by screen printing [28].…”