Embedding of bulk piezoelectric structures in Low Temperature Co-fired Ceramic

19.12.2014

Maciej Julian Sobocinskimaciej@ee.oulu.fi

Lectio praecursoria

Outline

• Piezoelectric effect• Low Temperature Co-fired Ceramic• Objectives of the thesis• Key results• Conclusion

Piezoelectric effect

Occurs in materials such as:– Rochelle's Salt, Quartz,

Tourmaline– BaTiO3, PZT– KNN, KMNB– PVDF– Bone, wood, silk, DNA

Areas of application:– Igniters, scales, ink-jet printers, microphones,

speakers, watches– Frequency standard – Force, pressure, acceleration sensors– SAW chemical and biological sensors– Actuators with nm resolution

Direct effect

Inverse effect

PZT - Lead zirconium titanate

©APC International, Ltd.

Most widely used piezoelectric material

Developed in 1952

Wide span of properties due to ease of modification

Benefits of PZT

Large piezoelectric coefficients

Durable and chemically stable

Easy to manufacture

Relatively inexpensive

Applications areas

• Sensors

• Actuators

• Transducers

Low Temperature Co-fired Ceramic

Presented in the 80s of XX century

Dielectric tapes and functional thick film pastes

Multilayer designs with buried passive components

Benefits of LTCC

Low temperature ~ 850 C

High speed conductors

Parallel processing

Durable, hermetic, resistant

Relatively inexpensive

©TDK-EPC

©IMST

Areas of applications

Microelectronics

RF components

Novel areas

LTCC evolution

Multilayer electrical circuits

Buried Passives C, L, R

MicrosystemsSensorsActuatorsSmart Packages

Objective of the thesisThe objective of the thesis was to integrate bulk piezoelectric elements in LTCC.

Test structures from four areas of applications have been manufactured and characterized:• Sensor• Actuator• Energy harvester• Microfluidic valve

Adhesive bondingCo-firing

Key results

Co-firing

Benefits of co-firing

Buried components

Hermetic encapsulation

High quality bond

Existing LTCC process flow

Creating electrical connections

Bulk piezoelectric properties

higher than in thick- and thin-

film

Actuators – optical filter

15 mm x 1.8 mm compact size 680 nm displacement 0,06º tilt capability Resonance frequency of 11 kHz Operating voltage 100 V

Individual arm signal connection

PZT

20 layers LTCC Inner

mirror

Outer mirror

Energy harvesters – wide band three beam energy harvester

39 mm x 39 mm x 2,7 mm 85 µW output power 5,4 % bandwidth Center frequency of 1147 Hz Enough power for temperature sensor,

accelerometer or Wi-Fi module working in burst mode

Sensors – bridge type accelerometer

High linearity High resistance to in-plane accelerations Sensitivity up to 6 mV/g Resonance frequency up to 12 kHz

Microfluidic systems – unimorph valve assembled on LTCC substrate

0.65 mm x 0.25 mm channels Embossed membrane Fast operating time Small leakage 125 V driving voltage

Pressure PressureFl

ow Tim

e

Conclusions

1. Integration of bulk piezoelectric structures and LTCC is possible

2. Co-firing of bulk PZT structures proved to be efficient way of integration that complements adhesive bonding.

3. LTCC works excellent as packaging for various piezoelectric components providing housing and electric circuitry.

4. Integrated piezoelectric bulk components broaden the span of LTCC applications.

5. Embedded bulk components can have better performance than thin- or thick-film components on LTCC.

Acknowledgments

Infotech OuluTekniikan EdistämissäätiöNokia Scholarship FoundationOulun yliopiston tukisäätiö

Thank You for Your attention