wide band gap - engineering center...gan sic reliable performance at higher voltages high junction...

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Wide Band Gap

Applications

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Wide Band Gap Applications

© 2019 KEMET Corporation

Wide Band Gap Overview

• Types:

– Gallium Nitride (GaN)

• Volume production since the 1990’s

• Primary Applications:

‒ RF

‒ LED

– Silicon Carbide (SiC)

• Commercial production since 2008

• Primary Applications:

‒ Power Inverters

‒ Low Voltage Power Distribution

• Advantages over Silicon

‒ Efficiency

‒ High Frequency

‒ High Temperature

‒ High Voltage

• Withstand 10x Voltage

Remember Carborundum?

Cree SiC MOSFET

Six-Pack Power Module

Especially attractive at 1.2+ kV


Wide Bandgap (WBG) Semiconductors

Density of StatesE

lectr

on

En

erg

y

Non-Conductive band

Semiconductor Material Bandgap

Energy (eV)

Germanium (Ge) 0.7

Silicon (Si) 1.1

Silicon Carbide (SiC) 3.3

Gallium Nitride (GaN) 3.4

WBG

ConductorsInsulators Semiconductors

10-20 10810410010-410-810-1210-16

Conductivity (S/cm)


Wide Bandgap (WBG) Semiconductors

Frequency (Hz)

Pow

er

(W)

100 1k 10k 100k 1M 10M 100M 1G 10G 100G

10

100

1k

10k

100k

1M

10M

100M The BIG 3 for WBG• Higher Voltages

• Higher Frequencies

• Higher Temperatures

Si

SiC

Si

Power Converter

GaN


Wide Band Gap Overview

• Lower System Losses– Increased Frequency

– Smaller Size

• Passive Component Impact:– 10x to 100x+ smaller value:

• Inductor

• DC Link capacitor

– Power Inverters:• 150 to 175+ degree C Snubber

• Snubber integrated into IC package (Ceramic)

• Ceramic DC Link‒ Frequency response

‒ Temperature

‒ Smaller capacitance required

‒ Up to 1200V and 1700V


Power Film Technology (Metallized PP)Effect of Higher Temperature and Frequency

• Higher Temperature

– Shorter Life, Lower Reliability

– Voltage & Current Limitation

• Higher Frequency

– Higher DF

– Voltage & Current Limitation


Future Power ElectronicsSemiconductor vs. Power vs. Frequency

Source: P. Friedrichs & M. Buschkuhle, Infineon AG, Energetica India, May/June 2016


Power Electronics Benefits

• Compared to Si, Wide Band Gap (WBG) IGBT and Power Modules:

– Are smaller

– Require less cooling

– Are more energy efficient

• Snubber and DC Link capacitors requirements for AC/DC conversions in high power inverters and converters will be reviewed

Conversion Efficiency Si Based WBG Based GaN or SiC

DC to DC 85% 95%

AC to DC 85% 90%

DC to AC 96% 99%

Source: Mouser Electronics, L. Culberson, 2016


Power Converter Capacitors

1 AC Harmonic Filter 3Φ 2 Snubber 3 DC Link

Typical Capacitor Types:

0 EMI / RFI

Filter 1Φ

L1

L2

CX

CY

CY

Power lineequipment

L1

L2

CX

CY

CY

Power lineequipment

AC/DCConverter

DC/ACInverter

1 12 2

3

AC ~

Power

Source

AC ~

Power

Load

System Overview:

0


WBG Capacitor Requirements

Capacitor RequirementWBG Semiconductor Trend

Smaller, low ESR, low ESL low

loss capacitors with high dV/dt &

current handling capability

Higher Switching Frequencies

20kHz → 100kHz → 100’s MHz

Higher Operation Voltages

400V → 900V →1200V→1700V

GaN SiC

Reliable performance at higher

voltages

High Junction Temperatures

105oC → 125oC → 200oC+

SiC

Reliable performance at elevated

temperatures ≥ 125oC with

robust mechanical performance

• Packaging close to the hot

semiconductor to:

‒ Lower ESL

‒ Minimize cooling costs


0.001

0.01

0.1

1

10

10 100 1000 10000

Capacitance (

uF

)

Frequency kHz

DC-LINK Capacitance vs Switching Frequency and Voltage of a 10kW Power Converter

400V 650V 1000V

Wide Bandgap TrendImpact on Capacitors

* Source: Prof. R. Kennel, Technical University Munich, Germany

Higher Voltage = Lower Capacitance

𝐶 =𝑃𝑙𝑜𝑎𝑑

𝑉𝑟𝑖𝑝𝑝𝑙𝑒 𝑉𝑚𝑎𝑥 −𝑉𝑟𝑖𝑝𝑝𝑙𝑒

2 ∗ 2 ∗ 𝜋 ∗ 𝑓𝑟𝑒𝑞𝑢𝑒𝑛𝑐𝑦


Capacitance Vs. Switching FrequencyExample: 10% Ripple for different power & voltage

Higher Power

More Cap

Higher Voltage

Less Cap

Frequency 10kW 50kW 100kW Voltage

20 5.24μF 26.19μF 52.38μF

40060 1.75μF 8.73μF 17.46μF

100 1.05μF 5.24μF 10.48μF

140 0.75μF 3.74μF 7.48μF

20 1.98μF 9.92μF 19.84μF

65060 0.66μF 3.31μF 6.61μF

100 0.40μF 1.98μF 3.97μF

140 0.28μF 1.42μF 2.83μF

20 0.84μF 4.19μF 8.38μF

100060 0.28μF 1.40μF 2.79μF

100 0.17μF 0.84μF 1.68μF

140 0.12μF 0.60μF 1.20μF


Capacitance vs. Switching FrequencyPolypropylene Film to MLCC

• For DC-Link Capacitors:‒ Lower capacitance required promotes

miniaturization due to:• Increasing switching frequency

• Higher voltages

• Lower capacitance is within the range of MLCC.‒ But these must be:

• Extremely reliable

• Over-temperature capable

• Over-voltage capable

• High current capable

• Mechanically robust

• PRO-TIP: MLCC for effective switching noise suppression when placed close to WBG where cooling is limited.


Ceramic Dielectric TypesHigh Energy Storage & MLCC Attributes

Paraelectric Ferroelectric Anti-Ferroelectric

EIA

Types

Dielectric

Class-I

C0G, C0H, U2J

CaZrO3

Class-II

X7R, X5R

BaTiO3

Class-II Similar to Y5V

PbLaZrTiO3

MLCC Attributes Target Paraelectric CaZrO3 Ferroelectric BaTiO3 Anti-Ferroelectric PLZT

Energy Storage High High Low High

Dielectric Constant K High Low High High

Dielectric Loss DF Low Low High Medium

Current Handling High High Low Medium

Mechanical Robustness High High Medium Low

Piezo (Electrostriction) Low Low High High

Voltage Stability High High Low Medium

Temperature Stability High High Medium Low

• C0G Development,

Leadless Stacks

for Higher Cap &

U2J Dielectric with

Higher K


3640 0.22µF 500V Ni BME C0G for 150oCTemperature Accelerated HALT

• MLCC were HALT tested at 260oC

at 1000, 1100, 1200 & 1300VDC

(n = 40, with Au term.)

• MTTF Vs. Voltage was recorded

• Voltage exponent ~ 19 @ 260°C

• Calc. MTTF @ 500VDC ~ 8500 yearsMTTF = 2934 min.

y = 7.13E+59x-18.6


Performance Comparison3640 Ni BME C0G vs. Competitor Cu PLZT

3640 0.23cm3 Vs. Cu PLZT 0.35cm3

– 3640 0.22μF has better accelerated life, stable cap with temperature / voltage & less ripple heating

– > 0.33μF with Leadless Stack Solutions


Ni BME C0G MLCC 3640 0.22µF 500V 150oCMechanical & Surface Mounted Performance

• Large Case C0G MLCC have

– High MOR

– Board Flex > 3mm

– Pass AEC Q200 temp. cycle testing

Tested

Pieces to

10mm DID

NOT FAIL

Case Size Cap.

(nF)

Rated

Voltage

(VDC)

1000 Cycles

-55oC to +125oC

50 Cycles

-55oC to +200oC

4540 27 1500 0/231 0/50

3640 15 2000 0/154 0/100

3040 39 1000 0/154 0/100

2824 33 630 0/154 0/100

Flex. Term. Or Lead

No Lead


Ni BME C0G MLCC 3640 0.22µF 500V 150oCESR & Current Handling @ 150oC 100kHz

• Lower DF & ESR reduce the power

dissipated

P = power dissipated

i = current

d = dissipation factor

f = frequency

C = capacitance

R = resistance, ESR

Ripple Current Life Testing

• No failures after 1000hrs @150oC

– 15ARMS 100kHz

– 10ARMS 100kHz with 400VDC Bias

ESR < 3 mΩ


3640 0.22µF 500V 150oCThermal Resistance & Ripple Current

• Measured Thermal Resistance correlates closely to calculated value of 14.1oC/W

• DC Voltage limits ripple current at lower frequencies ≤ 100kHz

• Maximum ripple currents are based on not exceeding the 150oC temperature or voltage capability


Performance

C0G 3640 220nF 500V

• PRO-TIP: Ideal for Resonant Capacitors


3640 0.22µF 500V 150oCPart Number & Properties

CKC 33 C 224 K C G A C TUCase Size Specification/ Capacitance Capacitance Termination Packaging

(L"x W") Series Code (pF) Tolerance Finish (Suffix / C-Spec)

CKC = KC-LINK 33 = 3640 C = Standard 2 Sig. Digits + K = ±10% C = 500 V G = C0G A = N/A C = 100% Matte Sn TU= 7" Reel, Unmarked

Number of Zeros

SeriesRated Voltage

(V)Dielectric

Subclass

Designation


Thermal Modeling & Ranges

Case Size 3640 0.22μF, 500V

• Thermal Resistance RƟ (oC/W) models correlate well with experimental results

Max. Cap. Range

Support customer thermal models for design-in

Cap, uF Cap Code 650 1000 500 650 1000 1200 1700 500 650 1000 1200 1700

0.0047 472

0.0056 562

0.0062 622

0.0068 682

0.01 103

0.012 123

0.015 153

0.018 183

0.022 223

0.033 333

0.039 393

0.047 473

0.056 563

0.068 683

0.082 823

0.1 104

0.15 154

0.18 184

0.22 224

0.47 474

KC-LINK1812 2220 3640

Voltage Rating Voltage Rating

RELEASED

Model


U2J MLCC Development

• BME C0G capacitors perform well for WBG applications requiring high bias

voltages such as in DC-Link & snubber applications.

• For lower bias voltages such as 48V DC-DC power supplies U2J MLCC with Ni

BME inner electrodes extend the Class-I capacitance range up to 50V rating.

• U2J MLCC properties are similar to C0G making them suitable for low loss

switching in resonant LLC designs.

• U2J has a small, predictable and linear capacitance change vs temperature.


KEMET U2J DielectricRelative Capacitance vs. Temperature

Class-I Dielectrics (Examples C0G: 0±30ppm/°C vs. U2J: -750±120ppm/°C)


Temperature Rise vs. Ripple Current

• BME C0G and BME

U2J both show high

current carrying

capability.

• Temperature rise

<14°C up to ripple

current of 10Arms.


U2J MLCC Range

Case Size

(Inches)

Case Size

(mm)

Rated

Voltage

(Vdc)

Maximum Available Capacitance CAP Increase

vs. current C0GC0G U2J

0402 1005

10 2.2nF 4.7nF +114%

16 / 25 2.2nF 2.2nF -

50 1.5nF 1.8nF +20%

0603 1608

10 15nF 33nF +120%

16 / 25 15nF 15nF -

50 6.8nF 10nF +47%

0805 2012

10 47nF 100nF +112%

16 / 25 47nF 56nF +19%

50 22nF 47nF +114%

1206 321616 / 25 100nF 220nF +120%

50 82nF 150nF +83%

1210 322516 / 25 220nF 330nF +50%

50 150nF 270nF +80%

1812 4532 50 220nF 470nF +114%

Standard and Flexible TerminationUnder Development


Leadless StacksIntroduction

• MLCC terminations are bonded together using Transient Liquid Phase Sintering

– Sn, Cu, Ag & Au term. finishes

• The resulting Leadless Stacks can be mounted on a circuit board using the

same assembly processes as an MLCC

• The capacitance in a given circuit board area is increased

US Patents 8,902,565 B2 & 9,472,342 B2


Leadless Stacks of 3640 0.22µF 500V MLCCElectrical Performance

• Higher Capacitance to ≈ 1µF

• Increased height of Leadless Stacks increases maximum inductance

• High Insulation Resistance to 200oC

10 mm 4-Chip 2.9 nH

5 mm 2-Chip 1.6 nH

2.5 mm MLCC 0.9 nH

2 µA

0.26 µA


What is TLPS?

• Low temperature reaction of low melting point metal or alloy with a high melting point metal or alloy to form a reacted metal matrix or alloy.

• Forms a metallurgical bond between 2 surfaces .

• Has high failure temperatures.

Transient Liquid Phase Sintering (TLPS)Basic Technology

CuSn TLPS

Heat


CTE Mismatch ComparisonLeadless Stacks vs. Leaded MLCC

Leadless Stack Mounted on

Circuit Board

J-Lead Stack Mounted on

Circuit Board

Mounting

Solder

Circuit Board

Small TLPS joint with low

CTE mismatch

J-lead absorbs

mismatch but

CTE mismatch

must be

minimized


Leadless Stacks of 3640 0.22µF 500V MLCCReliability

• Board Flexure is > 3mm

• No Failures 0/50 1000 cycles -55 to +150oC

• Low Shear Stress failure @19.1MPa (27.9kg)

is 15 X above the1.8kg AEC Q200 minimum


0.88µF Leadless Stacks (4 X 3640 0.22µF 500V)Orientation: Horizontal (Traditional) Vs. Vertical (Low Power Loss)

Vertical Orientation has:

• Higher SRF

• Lower ESR

Horizontal Vertical

3 MHz5.7 MHz Traditional Low Power

Loss

PN: C3640C884MCGLE

2.9 nH 0.9 nH


0.88µF Leadless Stacks (4 X 3640 0.22µF 500V)Ripple Current Heating: Horizontal vs Vertical Mounting

Vertical – Low Power Loss Orientation:

• More even heating

• Lower Temp. @ Steady State ≈ - 5oC

STEADY STATE12ARMS @ 140kHz WARMING UP

Top View

Side View

Horizontal - Traditional

Vertical – Low Loss

Side View

Heat dissipation

in Air above.

Heat dissipation

into Cu board.

Top View

34.9oC

29.2oC


Thermal Modeling3640 0.22µF 500V; 2 & 4 chip Leadless Stacks

Low Loss Model

Study thermal resistance with other boundary conditions• Forced air cooling or dielectric fluids

• Embedded in package


Trends

• Improved power conversion efficiency is driving the development of new systems

and components

• Wide Band Gap (WBG) substitute established Si technology

• Trends in Power Electronics:

‒ Higher switching frequencies

‒ Low loss MLCC with high ripple current capability

‒ High operating voltages 400V ➡800V

‒ Higher temperatures 105°C ➡ 150°C


Thank You!

wide band gap - engineering center...gan sic reliable performance at higher voltages high junction...

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