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SIC MOSFET SOOT SENSOR IN A CO-FIRED LTCC PACKAGE.
Maciej Sobocinski, David Bilby, David Kubinski, Jaco Visser, Mike Andersson, Jari Juuti, Anita Lloyd Spetz, Heli Jantunen
Microelectronics Research Unit, Faculty of Information technology and electrical engineering, University of Oulu, FinlandDiv. of Appl. Sensor Science, IFM, Linköping University, SE-581 83 Linköping, Sweden
Ford Motor Company, 2101 Village Rd. Dearborn, MI 48121, USA
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SOOT• Impure carbon particles• size ranging from nm to 2.5 um• Result of incomplete combustion of
hydrocarbons• Many man-made and natural sources
including diesel engines• Believed to be 2nd biggest reason for
global warming• diesel exhaust ¼ total hazardous
pollution in the air• Linked to several adverse health effects
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HOW TO DEAL WITH SOOT IN CARS• Using the right fuel• PM filter
• Stops most of the soot (99%)• Needs regeneration mechanism• Prone to damage costly repairs
• PM sensors• Before and after PM filter• Notifies when to regenerate the filter
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CURRENT PM SENSORS FOR CARS• Differential pressure • Radio frequency• Accumulating • Electric charge
Bosh
Continental
Delphi
©Bosh
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SIC CHARGE BASED SOOT SENSOR
Flow
SiC
Floating gate
Source Drain
Gate insulator
Benefits of SiC• wide band gap semiconductor • ten times the electric breakdown field• two times the electron saturation
velocity • three times the thermal conductivity• high temperature and power electronics
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LOW TEMPERATURE CO-FIRED CERAMIC
Cornerstone of modern electronics Presented in the 80s of XX century Dielectric tapes and functional thick film pastes
Benefits of LTCC High conductivity, low loss conductors Fast prototyping Parallel processing Durable, hermetic, resistant Relatively cheap
©TDK-EPC
©IMSTBlanking Screen printing Laser shaping Stacking Laminating Sintering
SIC CHARGE SENSOR IN LTCC
• Floating gate SiC MOSFET sensors• Co-fired with LTCC• Hermetic encapsulation• No brazing/wire bonding/resin encapsulation• Suspended electrode to enhance deposition of
soot
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MEASUREMENT SETUP
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SOOT CAPTURING MECHANISM
10SENSOR RESPONSE WITH ELECTROPHORETIC SOOT CAPTURING
AND WITHOUT
11SENSOR RESPONSE WITH HIGHER ELECTROPHORETIC VOLTAGE
Soot accumulation distorts the response
12SENSOR RESPONSE WITH HIGHER ELECTROPHORETIC VOLTAGE
Soot accumulation distorts the response
13INFLUENCE OF SOOT ACCUMULATION ON SENSOR OUTPUT
Clean Stuck with soot
Need for sensor regeneration!
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RESPONSE TO DIFFERENT CONCENTRATIONS
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CONCLUSIONS
• Floating gate SiC transistor can be used to detect soot• External electric field across the collection channel
increases speed of soot capturing• The electrophoretic voltage has its optimum [160 V
across 500 um gap in this case]• Sensor accumulates soot which mutes the response –
need for regeneration• Fast responses, dependent on concertation available at
the right conditions• Combination of SiC and LTCC allows placing of the sensor
directly in exhaust lines of diesel engines
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THANK YOU FOR YOUR ATTENTION
SENSORS - INTEGRATION THROUGH CO-FIRING
bulk insertion
Lamination:– 75 º C– 10 MPa
pressureCo-firing:
– 865 º C– 30’ in peak T
