1. Embedding of bulk piezoelectric
structures in
Low Temperature Co-fired Ceramic
19.12.2014
Maciej Julian Sobocinski
maciej@ee.oulu.fi
Lectio praecursoria

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

3. 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

4. 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

5. 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

6. LTCC evolution
Multilayer
electrical
circuits
Buried
Passives
C, L, R
Microsystems
Sensors
Actuators
Smart Packages

7. Objective of the thesis
The 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

8. Key results

9. 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

10. 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

11. 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

12. Sensors – bridge type accelerometer
 High linearity
 High resistance to in-plane accelerations
 Sensitivity up to 6 mV/g
 Resonance frequency up to 12 kHz

13. 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 Pressure
Flow
Time

14. 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.

15. Acknowledgments
Infotech Oulu
Tekniikan Edistämissäätiö
Nokia Scholarship Foundation
Oulun yliopiston tukisäätiö

16. Thank You for Your attention