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High Heat Flux Applications in Power Electronics 2005 1
High Heat Flux Applications in Power Electronics
Scott G. LeslieChief Technologist
Powerex IncYoungwood PA
High Heat Flux Applications in Power Electronics 2005 2
Power Semiconductor Device Power Switching Capacity & Application Map
Pow
er S
witc
hing
Cap
acity
(VA
)
Switching Frequency (Hz)Courtesy Mitsubishi Electric
Switching Frequency Capability
• Discrete SCR 10 kHz
• IGBT Module 60 kHz
• MOSFET 500 kHz
High Heat Flux Applications in Power Electronics 2005 3
• From the perspective of a high power semiconductor device manufacturer
• Primary focus is on applications utilizing power semiconductors> 500V & 50A
• Review power semiconductor device types & present cooling techniques - how they vary by application
• Discuss advances in silicon-based power semiconductor chip technology & impact on cooling requirements
• Discuss advances in semiconductor packaging technology & impact on cooling
• Cooling challenges associated with new power electronics applications
• Cooling challenges associated with new power semiconductor materials, i.e. SiC
High Heat Flux Applications in Power Electronics
High Heat Flux Applications in Power Electronics 2005 4
High Power Electronics Systems Trends
• More power delivered / switched in smaller volumes & less weight
• Higher voltage & higher current power semiconductor devices required
• Industry moving to power devices that are electrically isolated from heatsinks
• Higher efficiency demanded of systems & power devices
• Shift from analog to digital control of systems
• New circuit topologies have increased system efficiency & reduced stresses on power devices (soft switching, zero voltage & current switching (ZVS & ZCS))
• Move to eliminate fuses has increased overload requirements of power devices
• Switching frequency increases to the limit of the power devices
• Demand is for costs ($$/watt) to keep decreasing
• High reliability demanded
• Need for alternate energy generation & energy conservation is generating new applications
High Heat Flux Applications in Power Electronics 2005 5
High Power Semiconductor Device Trends
• Discrete & module devices have increased voltage & current capability
• Development of IGBT spurred revolution in high power electronics
• Power transistor modules have decreased in size – by 50% in some cases, thus increasing power density
• Incorporation of basic power electronic “building block” circuits in a module or assembly has reduced system size
• Integration of control, gate drive & sensing functions in power modules has
• Improved performance & reliability
• Reduced system size & parts count & required design effort
• New power semiconductor chip designs have reduced conduction &switching losses (trench gate, CSTBT, super-junction MOSFET)
• New semiconductor materials such as Silicon Carbide will extend voltage, frequency & operating temperatures beyond the capabilities of silicon
High Heat Flux Applications in Power Electronics 2005 6
How Do These Trends Impact Cooling?
• Higher voltage rated devices typically have higher power dissipation
• Higher frequency operation typically means higher power dissipation
• Smaller module sizes mean higher power dissipation densities
• Electrically isolated baseplate / heatsink makes it more difficult to cool power devices
• Air cooling not adequate – shift to liquid cooling
• Improve cooling efficiency – eliminate layers in thermal path
• Current overload “ride through” requirements require low transient thermal impedance designs
• Need more efficient air & liquid cooling methods
High Heat Flux Applications in Power Electronics 2005 7
Power Device Types
A discrete device consists of a “single”silicon element individually packaged in a
two or three lead package.
A module consists of one or more chips connected in a specific circuit
configuration enclosed in a plastic, ceramic or metal housing.
Diode / SCR / IGCT Diode / SCR / GTO / IGBT / MOSFET / BJT
High Heat Flux Applications in Power Electronics 2005 8
+
AC
+
-AC Switch Dual / Doubler Dual / Half H-Bridge
Power Electronics Building Block Configurations
High Heat Flux Applications in Power Electronics 2005 9
Power Electronics Systems Are Built From The Basic Building Blocks - 3 Phase Bridge Rectifier
+
AC
+
-
AC
+
-
AC
+
-
High Heat Flux Applications in Power Electronics 2005 10
Converter
Inverter
Brake
3 Phase Motor DriveFrom Basic Building Blocks
High Heat Flux Applications in Power Electronics 2005 11
Power Semiconductor Device Evolution
Electrical Isolation Integrated
Gate Drive & Protection Integrated
System in a Package
SCR / Diode / GTO Discretes
Intelligent IGBT Modules (IPM)
Discrete Assemblies Complete Power System Standard & Application Specific
BJT / MOSFET Discretes
Darlington Transistor / MOSFET / IGBT Modules
Module Assemblies
SCR / Diode Modules
System with Passives
Application Specific IPM
Semikron Skiip Pak
Powerex Pow-R-Pak
High Heat Flux Applications in Power Electronics 2005 12
Power Switch Cooling - Discretes
Liquid Cooled
Air CooledAdvantages• Double or single side cooled
• Lowest thermal impedance
• Good transient thermal impedance
Disadvantages• Compression bonded - devices require clamping forces up to 20,000 lbs. -- Increases with chip diameter
• Electrically “hot” heatsink - part of circuit
• Heatsink isolation required
• High resistivity water needed for liquid-cooled applications
• Clean, dry air needed for air-cooled applications
High Heat Flux Applications in Power Electronics 2005 13
Compression Bonded Discrete Device Thermal Paths
Double Sided Cooling(Disc Devices)
Semiconductor Element
Ambient
Package Contact
Ambient
Package Contact
HEAT
FLOW
HEAT
FLOW
Heatsink
Heatsink
Semiconductor Element
Ambient
Package ContactHEAT
FLOW
Heatsink
Single Sided Cooling(Stud Devices)
High Heat Flux Applications in Power Electronics 2005 14
Discrete Device Heatsinks - A Part of the Circuit
Dual / DoublerConfiguration
High Heat Flux Applications in Power Electronics 2005 15
Common Stud & Disc Device Air Cooled Aluminum Extrusions
23mm Stud/Disc
Up to 50mm Disc
Up to 67mm Disc
Up to 77mm Disc
2”
High Heat Flux Applications in Power Electronics 2005 16
0.001
0.010
0.100
1.000
10 100 1000 10000Average Current Rating (A)
Ther
mal
Impe
danc
e J
-C (C
/W)
Discrete Disc Module Discrete Stud
Power Device Thermal Impedance & Current Rating
12mm Stud
100mm Disc
77mm Disc
23mm Stud
30mm Module
67mm Disc
50mm Disc
40mm Disc
40mm Module
33mm Disc
30mm Disc
2 x 67mm Module
23mm Disc
16mm Stud
Thermal Impedance (J-C) & Current Rating Relationship for 1600V PC SCR
High Heat Flux Applications in Power Electronics 2005 17
Increase in Device Current Rating if Heatsink is Capable
50mm 1400V SCR Disc Device Average Current Rating vs Case Temperature
0
20
40
60
80
100
120
0 500 1000 1500 2000 2500 3000
Average Current Capability (A) (180 Deg Conduction)
Max
Cas
e Te
mpe
ratu
re
(C) 70C
SCR Rated @ 70C Case
Increase Current Capability by Reducing Case Temp With More Efficient Heatsinks
20C Case Temp Reduction Leads to 25% Increase in Average Current Capability & 50% Increase in Power Dissipation
50mm 1400V SCR Disc Device Average Power Dissipation
0
1
2
3
4
5
6
0 500 1000 1500 2000 2500 3000
Average Current Capability (A) (180 Deg Conduction)
Avg
Pow
er D
issi
patio
n(k
W)
0
100
200
300
400
500
600
Avg
Pow
er D
ensi
ty
(W/c
m2)
High Heat Flux Applications in Power Electronics 2005 18
Air Cooled Heatsink Limitations for Large Diameter Disc Packages
1600V SCR Power Dissipation @ Rated Current
0123456789
10
40 50 60 70 80 90 100 110Chip Diameter (mm)
Pow
er D
issi
patio
n (k
W)
0102030405060708090100
Pow
er D
ensi
ty (W
/cm
2)
Power Dissipation (W) Power Density (W/cm2)
Air Cooled HeatsinksLimit Device Performance
• Tcase = 70C
• Inlet Air = 40C & 1000 LFM
• Sink Length = 5 X Device Dia.
• Liquid Cooled Flow = 3 GPM.
Sink - Ambient Thermal Resistance To Permit Rated Current Operation For 1600V SCR
0
0.01
0.02
0.03
0.04
0.05
0.06
40 50 60 70 80 90 100 110Chip Diameter (mm)
Ther
mal
Res
ista
nce
(C/W
)
Sink - Ambient Thermal Resistance Sink Length 5X Device Dia Liquid Cooled
High Heat Flux Applications in Power Electronics 2005 19
Heatsinks for Discrete Stud & Disc Devices - Summary
Air Cooled• Low cost approach adequate, but limits capability of power devices
• Large heat capacity & long thermal time constant good for short term overloads
• Bonded fin family of heatsinks presently not capable of high clamping pressures (5,000 - 20,000 lbs) required by large disc devices
Liquid Cooled• Not an option in many applications
• Works well for large diameter devices > 77mm
• Field replacement of power device difficult
• Insulating liquids required for electrical isolation
High Heat Flux Applications in Power Electronics 2005 20
Is it Possible?
Can a thin layer with a very high thermal conductivity, high delectricstrength & high compression strength like diamond be applied to the device contact area of an extrusion?
Result -- Isolated discrete device heatsink with minimal added thermal resistance.
Disc Device
Can a heat pipe / bonded fin heatsinkhybrid be developed for large diameter disc devices? Can the heat pipe materials & liquid have electrical insulating properties?
Clamp
Result – Low thermal resistance, isolated air cooled heatsink for large diameter discs.
High Heat Flux Applications in Power Electronics 2005 21
Power Switch Cooling - Modules
Liquid Cooled
Air CooledAdvantages• Do not require external clamping
• Isolated base plate permits grounded heatsink
• Mount multiple modules on a common sink
• Air & liquid quality requirements are much lower
• Basic circuit building blocks in one package
Disadvantages• Higher thermal impedance than discretes
• Lower average current rating - 40% of disc device with same chip
• Lower overload capacity in some cases
Compression Bonded
Soldered & Wirebonded
High Heat Flux Applications in Power Electronics 2005 22
Planar Chip Mounting Methods – Thermal Paths
Semikron Compression Bonding in Skiip Packs: Conventional Solder Down
Westcode/IXYS Compression Bonded IGBTsin Disc Packs:
Semikron -PCIM Euro 2005 Proceedings
Westcode -PCIM Euro 2005 Proceedings
Powerex –Substrate Soldered Directly to MicrochannelChill Plate
High Heat Flux Applications in Power Electronics 2005 23
1200V Transistor Chip Power Density Trends
Improvements in IGBT cell density, conduction & switching losses have resulted in higher switching power densities while power dissipation densities remain relatively constant
Switching Power Density for 1200V Power Transistor Chips
0
20
40
60
80
100
120
1984 1986 1988 1990 1992 1994 1996 1998 2000Year
Switc
hing
Pow
er D
ensi
ty
(kVA
/cm
2)
Darlington Planar IGBT Trench IGBT
Switching Power (kVA) = 1/2 Vrated x Ic (peak turn-off rated)
Power Dissipation Density for 1200V Power Transistor Chips
0
20
40
60
80
100
120
140
160
180
200
1984 1986 1988 1990 1992 1994 1996 1998 2000Year
Rat
ed P
ower
Dis
sipa
tion
Den
sity
(W
/cm
2)
Darlington Planar IGBT Trench IGBT
Conduction Losses Only @ Rated Avg Current & 100% Duty Cycle
High Heat Flux Applications in Power Electronics 2005 24
High Frequency Operation Increases Chip Power Dissipation
Power Dissipation Density Increases With Switching Requency
0
100
200
300
400
500
600
700
800
900
0 10 20 30 40 50 60Switching Frequency (kHz)
Pow
er D
issi
patio
n D
ensi
ty (W
/cm
2)
Gen 5 (2000)
Gen 3 (1992)
Gen 4 (1998)
Vcc = 600V, Ic = 100A, 50% Duty Cycle -- Calculated
Conduction vs Switching Loss Trade-Off
High Heat Flux Applications in Power Electronics 2005 25
Higher Module Voltage Ratings Increase Chip Power Dissipation
Vcc = 50% Rated Vce, Ic = 400A, 50% Duty Cycle -- Calculated
400A IGBT Module Power Dissipation vs Voltage Rating
0.1
1
10
100
0 500 1000 1500 2000 2500 3000 3500 4000 4500 5000
Module Voltage Rating
Pow
er D
issi
patio
n (k
W)
DC 25 kHz 50% Duty Cycle 50 kHz 50% Duty Cycle
Conduction Loss Only
Total Power Dissipation
High Heat Flux Applications in Power Electronics 2005 26
Power Dissipation Density vs Cooling
Ref: Beckedahl et.al. (Semikron) PCIM Euro 2005
High Heat Flux Applications in Power Electronics 2005 27
IGBT Module Footprint Area Reduction (1200V, 400A Dual)
Switching Power Density for 1200V 400A Dual IGBT Modules
0
1
2
3
4
5
6
1990 1992 1994 1996 1998 2000Year
Mod
ule
Switc
hing
Pow
erD
ensi
ty (k
VA/c
m2)
Planar IGBT Trench IGBT
Switching Power (kVA) = 1/2 Vrated x Ic (peak turn-off rated)
1200V 400A Dual IGBT Module Footprint Area Reduction
0%
20%
40%
60%
80%
100%
120%
1990 1992 1994 1996 1998 2000Year
% R
educ
tion
Planar IGBT Trench IGBT & Low Inductance Pkg
Reduction in IGBT package footprints have resulted in higher module switching power densities, higher power dissipation densities & lower inductance
High Heat Flux Applications in Power Electronics 2005 28
Power Switch Evolution -Integrated “Intelligent” Power Module = IGBT + Smarts
Intelligent Power Module
• Gate drive, temperature sensing & protection elements are integrated in the power switch package
• Protection for:
• Overtemperature
• Overvoltage & current
• Low supply voltage
• Fault signal feedback
• Improves switch performance since protection functions are integrated in package
• Ease in application
LVASICGate DriveProtection:
OverCurrentOver
TemperatureUnder VoltageVC
Temp. Sensor
FO
CIN
V1
IPM
15V
+
+
LVASICGate DriveProtection:
OverCurrentUnder Voltage
VC
FO
CIN
V1
15V
+
+Logic level
control Inputs
LVASICGate DriveProtection:
OvercurrentOver TemperatureUndervoltage
VC
Temp. SensorTemp. Sensor
FO
CIN
V1
IPM
15V
+
LVASICGate DriveProtection:
OvercurrentUndervoltage
VC
FO
CIN
V1
15V
+
Logic level
control Inputs
DC-DC Converter
High Heat Flux Applications in Power Electronics 2005 29
Increased Module Integration -- Size Reduction 600V 150A Servo Motor Controller IPM
On chip current & temperature sensing along with advanced
package design resulted in 30% - 40% reduction in module footprint for same
current rating
Reduced cell pitch &
increased density
results in lower losses
High Heat Flux Applications in Power Electronics 2005 30
System Impact of Increased Integration & Reduced Module Size
Smaller module resulted in smaller system & heatpipe elimination.
Heat Pipe
Gen 3 Module
Gen 4 Module
High Heat Flux Applications in Power Electronics 2005 31
Conventional IPM
Version 3 ASIPM
Small Motor Drive Integration
Rectifier
Current Sensor
Optocouplers
• Small Servo Drives• Pumps• Low End Industrial Drives• HVAC, Compressors and Blowers• Robotics
High Heat Flux Applications in Power Electronics 2005 32
ResinMold
Power ChipsIGBT, FWDi
Al Bond Wire Au Bond Wire
HVIC
Power Pins Control Pins
New Mini DIP-IPMOriginal DIP-IPM
Copper Block – Heat SpreaderMold Resin
Power ChipsIGBT, FWDi
Al Bond Wire Au Bond WireHVIC
Power Pins Control Pins
transfer-mold
package
lead-frame
bare HVIC die
bare IGBT die
bare FWDi die
Appliance Motor Drives
High Heat Flux Applications in Power Electronics 2005 33
• Power switches
• Energy storage devices
• Current sensing
• Gate drives
• Protection
• Heatsinking
Assembly Subsystems – Beyond Systems in a Module
Air Cooled
Liquid Cooled
Powerex Pow-R-Pak
Semikron Skiip Pack
High Heat Flux Applications in Power Electronics 2005 34
Large Off Road Vehicle Motor Drive Application
• Front end loader with a 400 HP motor driving each wheel• Four independent motor drives fed by 2000HP on-board generator
Motor Drive Electronics Cabinet
High Heat Flux Applications in Power Electronics 2005 35
Motor Drive Topology
• Front end converter, Brake chopper, Inverter for each phase• Four subsystem assemblies per motor – 16 per vehicle• Three Rectifier & six IGBT modules per motor
Single Motor Topology
Single Motor Topology
High Heat Flux Applications in Power Electronics 2005 36
Module Design Reduces System Inductance & Complexity
1200V, 900A Mega Power Dual IGBT Module
High Heat Flux Applications in Power Electronics 2005 37
Drive System Integration
Folded Fin Heatsink
Motor Leg Inverter
Converter & Brake Chopper
Air Cooled
High Heat Flux Applications in Power Electronics 2005 38
UPS & Transfer Switches• Air cooled
• Primarily use isolated base plate modules
• Large systems still use discrete devices
• Overload requirements
High Heat Flux Applications in Power Electronics 2005 39
• UPS, Transfer Switches, Motor Drives
• Duration - millisecond to minutes
• Need high capacity material close to chip
• Short circuit overload (< 50 us) – heating is in chip only
Low Transient Thermal Impedance for Overload Capacity
Maximum Transient Thermal Impedance
0.00
0.01
0.02
0.03
0.04
0.05
0.001 0.01 0.1 1 10 100 1000
Time - t - Seconds
Ther
mal Im
peda
nce -
Rjc
- °C/
W
(Junction To Case)
High Heat Flux Applications in Power Electronics 2005 40
Power Generation & Conditioning
• Air cooled
• Isolated base plate modules
High Heat Flux Applications in Power Electronics 2005 41
Induction Heating & Melting
Large metal melting systems use SCRs & are water cooled
Smaller high frequency heating / sealing systems use IGBTs or MOSFETS & are air cooled
High Heat Flux Applications in Power Electronics 2005 42
Large DC Power Supplies
• Discrete or module SCRs, Diodes
• IGBT modules
• Air or liquid cooled
Ref: Applied Power Systems Inc.
High Heat Flux Applications in Power Electronics 2005 43
Military & Aerospace - Future Trends• More naval, aerospace & military applications are going electric
• Electric propulsion for military vehicles & ships
• Electromagnetic weaponry & aircraft catapults
• Active power conversion systems replacing conventional transformers on ships
• Aircraft “fly by wire” actuators for flight surface control
• Impact on power electronic systems & devices:• High power densities & high temperature device operation
• Power electronics on aircraft & military vehicles cooled with engine oil
• Higher operating temperatures & increased cooling efficiency required
• Higher temperature power semiconductor devices needed – SiC
• Integration of chill plate into ceramic insulator of module
High Heat Flux Applications in Power Electronics 2005 44
Aircraft Applications
Aircraft Generator / Starter
• AlSiC baseplates
• Cooled with jet engine oil
Pin fin heat sink diode assembly is cooled by flowing jet engine oil
“Fly by Wire” - Servomotor actuators for flight surface control Ref: PCIM Euro 2005 Van Den Bossche --
AIRBUS.
High Heat Flux Applications in Power Electronics 2005 45
Future Electric Ships Will Make Extensive Use ofFuture Electric Ships Will Make Extensive Use ofPower Conversion Systems That Require a Power Conversion Systems That Require a ““DC LinkDC Link””
Capacitive Energy Storage100's MJ
Inertial Energy Storage100's MJ
Direct Connection10's MW
G G
NS
Electric Weapon PowerPropulsion Power
AC & DC Loads10 - 15 MW
AC Motors - 70 Plus MW
Power Generation - Rectified Alternators - 80 Plus MW
Bi-DirectionalPower Flow
Rectifiers
DC
DC
DC
DC
DCAC
AC
DC
Rail GunEMALS
Rail Gun
Laser/Others
DC Link
DCDC
DCAC
DCDC
DC Motors - 70 Plus MW
Low VoltageIFTP Ship Service Power
PCM-1
PCM-2
Ship Propulsion & Power Conditioning
CVN-78
High Heat Flux Applications in Power Electronics 2005 46
Shipboard Power Conditioning - PCM-2 -- 800 Vdc to 450 Vac
SHIPS SERVICE
INVERTER MODULE
(SSIM)
• PCM-2 contains modular 90 kW DC-AC inverters (800 VDC/450 Vac 3 ph)
• Current design has 6 SSIMs rated at 540 kW
• Design expandable to 3.24 MW
• NEMA 4 Sealed Cabinet uses internal air-cooled design to air to water heat exchanger. Power electronics in each SSIM are cooled by a sealed water-cooled cold plate.
• IGBT modules & liquid heatsinks comprise < 20% of SSIM module
High Heat Flux Applications in Power Electronics 2005 47
Ceramic Micro-Channel Liquid Cooled Heatsink
Ref: Schulz-Harder et.al. - Curamik
High Heat Flux Applications in Power Electronics 2005 48
Power Semiconductor Module --- Double - Sided Cooling
High Heat Flux Applications in Power Electronics 2005 49
Silicon Carbide Power Devices - Benefits
Wide BandgapHigh Breakdown Field
High ThermalConductivity
Robust
LowConduction
losses
HigherVoltage
LowSwitching
losses
HighTemperature
Operation
HighSurge
Current
HighEfficiency
Smaller Lighter LessCooling
LowerEMI/RFI
MoreReliable
MATERIAL
DEVICE
SYSTEM
Courtesy of Cree Inc.
High Heat Flux Applications in Power Electronics 2005 50
Silicon Carbide Power Devices Switching Power Dissipation Comparison
Si PiN DiodesReplaced with SiC Schottky Diodes
Agarwal et al: 1st Annual Ground -Automotive Power & Energy Symposium 2005
Courtesy of Cree Inc
125 degree C 125 degree C 125 degree C 125 degree C 250 degree CSi IGBT w/ Si IGBT w/ SiC MOSFET w/ SiC BJT w/ SiC BJT w/
Parameter Units Si PiN SiC Schottky SiC Schottky SiC Schottky SiC SchottkyPeak reverse current Ipr (A) 6 1 2 1.9 1.3
Reverse recovery time Trr (nS) 148 30 14 15 20Recovery charge Qrr (nC) 540 20 14 14 13
Diode loss turn-off Eoff Diode (mJ) 0.16 0.02 0.015 0.016 0.014Diode loss turn-on Eon Diode (mJ) 0.03 0.02 0.014 0.02 0.013
Diode loss total Ets Diode (mJ) 0.19 0.04 0.029 0.036 0.027Switch loss turn-on Eon SW (mJ) 0.98 0.44 0.2 0.29 0.28Switch loss turn-off Eoff SW (mJ) 0.57 0.41 0.13 0.34 0.3Switch loss total Ets SW (mJ) 1.55 0.85 0.33 0.63 0.58
Total (Switch + Diode) Ets (mJ) 1.74 0.89 0.36 0.67 0.61% Reduction 49% 79% 61% 65%
Switching Comparison of Si and SiC 1200 Volt, 5 Amp Devices*
High Heat Flux Applications in Power Electronics 2005 51
750A -1200V Oil Cooled Si/SiC IGBT Module
Replace Si ultra fast diodes with SBD SiC to reduce switching losses for Diode and IGBTPorous metal heat sink with high heat transfer capability
50A/1200V SiC SBD (24x)
150A CTSBT IGBT (6x)
IGBT Gate
IGBT Emitter
Heat-sink (IGBT Collector)
Chip
The tortuous fluid path enhances fluid mixingSoldered bed design yields contiguous solid phase for enhanced thermal spreading via conduction.The porous media provides a large surface area for convective transport to the coolant.
Integral Heat Sink
Aga
rwal
et a
l: 1st
Annu
al G
roun
d -A
utom
otiv
e P
ower
& E
nerg
y S
ympo
sium
200
5
UDLPUDLP
High Heat Flux Applications in Power Electronics 2005 52
Shipboard Power Conditioning Systems With SiC Devices
CVN-78
• 10 kV, 110A SiCMOSFET Dual Module
• 200C junction operating temperature
• 20 kHz
• Liquid cooled, isolated base module
• Power dissipation 250 – 500 W/cm2
High Heat Flux Applications in Power Electronics 2005 53
Power Module Cooling - Where Do We Go From Here?
• More direct mounting (solder & compression) of chips / ceramicsubstrate on liquid cooled substrate
• High quality Ni or Au plating on soldering surface of chill plate
• Flatness of mounting surface important
• Concern about CTE match of materials for long term reliability
• New heatsink materials & composites
• Micro-channel sinks – High potential – what about reliable long term operation?
• Replace DBC aluminum nitride insulator with DBC diamond layer bonded directly to chill plate?
• Ceramic micro-channel liquid cooled chill plate potential?
• Double sided cooling of IGBT & MOSFET chips in modules?