© TOKIN 2019

Soft magnetic Metal-flake Composite Material Suitable for High Frequency Power Modules

19 Mar. 2019

Ken’ichi Chata’niTOKIN Corporation

© TOKIN 2019

Ken’ichi Chata’ni, Ph.D.(Physics)

Manager, Advanced Materials R&D DivisionTOKIN Corporation7-1 Koriyama 6-Chome, Taihaku-ku, Sendai, Miyagi 982-8510 Japan

kenichichatani@kemet.com

© TOKIN 2019

TOKIN History

1930 19801930

Name changed to TOKIN Corporationbecome a 100% subsidiary of the United States based KEMET Corporation

1990 2000 2010

April 1938 as University Startups

Established to commercialize KS magnetic steel (by Prof. Kotaro Honda) and Sendust (by Prof. Masumoto Hakaru), both invented at Tohoku Imperial University, Sendai, Japan.

October 1988

April 2002

February 2013

Became NEC TOKIN Corporation(3 SBUs from NEC: capacitors, relays, and batteries)

Name changed toTOKIN Corporation

Started business and capital partnership with KEMET Corporation

April 2017

Main ProductsTantalum capacitors,

Electric double-layer capacitors,EMI/Noise suppression components,

Power inductors, Transformers,Piezoelectric devices, Sensors.

© TOKIN 2019

Material characteristics of FlakeCompositeTM ,in comparison with existing magnetic materials.

-Permeability, magnetic saturation, core loss, etc.

Inductor performance benchmarking.

PCB embedded inductor test fabrication result.

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Demands: Shorten the distance from DC/DC converter to the load.

Higher DC current / Higher switching frequency

Motivation

Back surface mountProcesser

Inductor Inductor

Inductor

Processer

PCB embedding

Processer

3D mount

Processer

Conventional

Spread of GaN Integratable L, C

Low-profiled inductor for integrated DC/DC converter is required.PCB embed enabling magnetic material will also be required in future.

Inductor

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FlakeCompositeConventional Metal composite

Permeability >300(Same as ferrites)

< 40

Metal-flakeCompactingTechnology

Thickness >0.5mmBrittle

>50μmFlexible

Heat durability <200℃Organic binder

>200℃Inorganic binder

Enable PCB Embedding

Suitable for power modules

Smaller component's volume

What is FlakeCompositeTM?

t=50μm

© TOKIN 2019

0.0

0.5

1.0

1.5

2.0

100 100010

Bs(T

)

MnZnNiZn

CoZrO(film)

CoZrTa(film)

CoＮｉFe(film)

Fe nanocrystal

Permalloy

FeSiAl(Sendust)

FeSi

Fe amorphous

Permeability (1MHz)

PCB embeddedMagnetic Material

Conventional metal composite Low permeability

Ferrites

Deposited Film

Brittle

Difficult to increase the core volume.

High permeability (300 at 1 MHz.)50µm to 2mm thicknessThin, Flexible(Rigid)

FlakeComposite

Comparison of Magnetic Materials for PCB Embedding

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Powder Shape Permeability Min. bend radius(Arb. unit)

35 10

160 4

300 130µm

Effect of Powder Shape on Permeability and Flexibility

10 times improvement inpermeability and flexibility

t=50μm

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0

100

200

300

400

0.1 1 10 100

Perm

eab

ility

(Re, I

m)

Frequency(MHz)

NiZn ferrite

FlakeComposite

μ’// = 300

μ⊥≦ 5

Comparable to NiZn ferrite for MHz power application.

Frequency dispersion of complex permeability

LimitationLower Out-plane permeability.

Perm

eabi

lity

(Re,

Im)

Frequency (MHz)

Permeability vs Frequency

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0

500

1000

1500

-50 -25 0 25 50 75 100 125 150 175

Pcv(m

W/cc, 1M

Hz B

m25m

T)

Temp (℃)

0

1000

2000

0 1 2 3 4 5

Pcv(

mW

/cc)

f(MHz)

f×Bm=25MHz・mT23℃

Core loss of FlakeComposite is comparable to NiZn ferrite,but much larger than MnZn ferrite at few MHz.

NiZn ferrite

MnZn ferrite

ConventionalMetal Composite

Core Loss vs Temp.

FlakeComposite

FlakeComposite

Core Loss

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0

0.1

0.2

0.3

0.4

0.5

0.6

0.7

0 2000 4000 6000 8000

B (T

)

H (A/m)

Soft-saturation in FlakeComposite.

Smaller drop of saturated magnetic moment against temperature, comparing to MnZn ferrite.

125℃

25℃

MnZn ferrite

FlakeComposite

ConventionalMetal Composite

Magnetic Saturation (BH curve)

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0

10

20

30

40

50

60

70

80

0 2000 4000 6000 8000

Perm

eabi

lity

Hdc(A/m)

125℃

25℃

MnZn ferrite

FlakeComposite

ConventionalMetal Composite

In metals, permeability under DC-bias field is insensitive to temperature.

In metals, permeability survives under high DC-bias field.

In MnZn ferrite and FlakeComposite, effective permeability under zero bias field is tuned to be 70 by corresponding demagnetizing coefficient, i.e, air-gap.

N=0.01384

N=0.01091

N=0

Permeability under DC-bias Field

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0

50

100

150

200

250

300

0.1 1 10 100

Perm

eabi

lity(

Re,

Im)

Frequency(MHz)

0102030405060708090

100

0 500 1000

Perm

eabi

lity

Chan

ge(%

)

Plane Pressure(kgf/cm2)

Only 7.6％ permeability decreaseunder 1000kgf/cm2 compression.

Plane Pressure(kgf/cm2)

-7.6%

FlakeComposite

Apply 1000kgf/cm2 plane pressureon the toroidal core.

After 1000kgf/cm2compression

Initial

Only 2.7% permeability decreaseafter 1000kgf/cm2 compression.

No apparent damage was found.

Effect of Plane Compression

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Material characteristics of FlakeCompositeTM ,in comparison with existing magnetic materials.

-Permeability, magnetic saturation, core loss, etc.

Inductor performance benchmarking.

PCB embedded inductor test fabrication result.

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Lateral flux

h

Vertical flux

1turn

2turn3turn

Lateral Flux Inductor Structure

Qiang Li, Fred C. Lee, “High Inductance Density Low-Profile Inductor Structure for Integrated Point-of-Load Converter”, 2009IEEE Applied Power Electronics Conference and Exposition (APEC), Washington, District of Columbia, Feb. 15 – 19, 2009, pp.1011 – 1017.

Dongbin Hou, Yipeng Su, Qiang Li, Fred C. Lee, “Improving the Efficiency and Dynamics of 3D IntegratedPOL”, IEEE Applied Power Electronics Conference and Exposition (APEC), 2015, pp. 1011 – 1017.

FlakeComposite is suitable to demonstrate the proposed advantage of “Lateral flux” inductor design.

As inductor goes thinner, the advantage of “Lateral flux” inductor structure should be more prominent.

© TOKIN 2019

0

10000

20000

30000

0 1 2 3 4 5 6

L x

Imax

/ DC

R(nH

･A/

mΩ

)

Inductor Height(mm) Imax≧20A

FlakeCompositeLateral flux

The advantage of FlakeComposite Lateral flux inductor becomes prominent as the inductor height goes lower.

Benchmarking Result

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Storage Result (N=22)

-50℃ 1000h Pass

150℃ 1000h Pass

Unbiased HastWith MSL 3Pre-Conditioning

130℃85% 96hPass

33.3psia(2.3atm)

JESD22-A119 JESD22-A103 Condition B

Heat Cycle

-65⇔150℃ 500cycle Pass

JESD22-A104 Condition C Soak Mode 4

JESD22-A118

MSL test (Level 1)Pre-bake 125℃ 24h

PassMoisture Soak 85℃85%RH 192hReflow 260℃ x 3

J-STD-020E

Sample Structure・Tin plated lead frame and Cu pins (without insulation coating) are attached on the FlakeComposite core. Image

Hi Temp and Humidity

85℃85% 1000h PassMIL-STD-202 Method 103

• Acceptance Criteria: ・ Change of Ls, Rs and DCR<10% pre-test to post-test.・ No cracks, chips or discoloration

AEC-Q200 compatible. (RoHS2.0, Halogen free, REACH compliant.)

13mm

Reliability Test Example (On samples to CPES)

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PCB embedded inductor to minimize:- PCB board area.- parasitic inductance of Cu trace.

Power Inductors

Ferrite FlakeCompositeTM

40% height reduction with FlakeComposite inductor.

Embedded noise shielding layer

Flexible shielding layer (for WPT)- Combined with PCB embedding technology.

FlexSuppressor® Flex "Embedded" Suppressor

Magnetic SheetsApplication Target

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Material characteristics of FlakeCompositeTM ,in comparison with existing magnetic materials.

-Permeability, magnetic saturation, core loss, etc.

Inductor performance benchmarking.

PCB embedded inductor test fabrication result.

© TOKIN 2019

Y. Su, W. Zhang, Q. Li, F. C. Lee, and M. Mu, "High frequency integrated Point of Load (POL) module with PCB embedded inductor substrate," in Energy Conversion Congress and Exposition (ECCE), 2013 IEEE, 2013, pp. 1243-1250.

Similar prototypes were fabricated.

PCB Embedded Inductor Demonstrated by CPES

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2 turnDCR2.8mΩ

3 turnDCR4.4mΩ

With insertedpins

0.8mΩ

With insertedpins

2.1mΩ

0

50

100

150

200

250

300

350

0 10 20 30 40

L(nH

) @

1MHz

Idc(A)

2 turn

3 turn

Upside Downside

Upside Downside

t2.5mm

12mm

Embedded core size9 x 8 x t1.5mm

PCB Embedded Inductor Prototype

Cu t=0.2

CuΦ

=0.8

FlakeComposite

FlakeComposite

t=2.7mmFR4

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0

10

20

30

235 255 275 295 315

Cou

nt

L(nH, 1MHz)

0

10

20

30

105 115 125 135 145

Cou

nt

L(nH, 1MHz)

0

25

50

75

100

125

150

1 10 100 1000

L(nH

)

Frequency(MHz)

1

10

100

1000

1 10 100 1000

|Z|(Ω

)

Frequency(MHz)

0

100

200

300

1 10 100 1000

L(nH

)

Frequency(MHz)

1

10

100

1000

1 10 100 1000

|Z|(Ω

)

Frequency(MHz)

2 turn (n=100)

3 turn (n=100)

－10%

±3σ

±3σ

+10%Ave.

125nH

Ave.277nH－10% +10%

SRF=400MHz

SRF=250MHz

Tight tolerance of inductance is readily achieved in prototypes.

Dispersion of Inductance , |Z|

© TOKIN 2019

FlakeCompositeTM is:-Thin, Flexible, PCB-embed-enabling, -High permeability at multi-MHz swithcing frequency,-High-saturated magnetic moment than ferrite,-High temperature tolerant

soft magnetic material for power supply application.

We believe this material will contribute to the miniturization of electronic circuits, especially in:

- DC/DC converters,- Wireless Power Transfer system.

We are continuing to scale-up this technology for use in several applications.

Summary

Thank you very much for your attention.