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1

Newly Developed Low-Transmission-Loss Multilayer Materials for PWBs Applied to High GHz Bands

Newly Developed LowNewly Developed Low--TransmissionTransmission--Loss Multilayer Loss Multilayer Materials for Materials for PWBsPWBs Applied to High GHz BandsApplied to High GHz Bands

HikariHikari MuraiMurai, , YasuyukiYasuyuki Mizuno, Hiroshi Shimizu, Mizuno, Hiroshi Shimizu, Makoto (Makoto (MakMak) Kato and Kenichi (Ken) Ikeda) Kato and Kenichi (Ken) Ikeda

Tsukuba Research LaboratoryTsukuba Research LaboratoryTelecommunication Materials Development CenterTelecommunication Materials Development Center

Printed Wiring Board Materials R&D Dept. Printed Wiring Board Materials R&D Dept. Printed Wiring Board Materials Div.Printed Wiring Board Materials Div.

Hitachi Chemical Hitachi Chemical Co.,LtdCo.,Ltd..

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2

1. Requirement of material for high-frequency PWBs2. New low-transmission-loss multilayer materials 2.1 Development concept 2.2 Characteristics of new material2.3 Pb-free reliability and process ability2.4 Profile-free copper foil technology2.5 High-frequency performance of PWBs

3. Conclusions

Outline

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3Background ; Advanced Telecommunications

Sophisticated telecommunications Sophisticated telecommunications NetworksNetworks

High-speed transmission of large-volume data

Signals on PWBs Higher frequency• High-frequency device & module (PA, VCO, Filter)• Antenna & Processor of base transceiver station• Server, Router, Transport, etc

Router

Intelligent Transport System

/ GPS/ VICS/ ETC

Home Network

OA Network

LAN

Internet

Mobile Telecommunication

/ Mobile station/ Base transceiver station/ Network controller / Processing equipment/ Switching system

Server

Satellite Communication

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4Roadmap of Infrastructure-Communication Network

Servers Transmission Rate: 1.5Gbps⇒3Gbps Dk:4.0, Df:<0.010 LevelRouters 30Layers ⇒ 40 Layers Lead-Free applicable

Narrow Pitch, TH reliability, CAFSymmetrical Packaging

Reflow Temp: 260oCSuper Computers Transmission Rate: 5Gbps⇒10Gbps Dk:3.5, Df:<0.005 Level

High-End Giga bit Router 30Layers ⇒ 50 Layers Heat Resistance for Lead Free

Base Station:Back panel Reflow Temp: 260oC TH reliability, CAF

RF modules for Halogen Free Materials applied Dk:<3.7, Df:<0.007 LevelMobile Handset Devices Frequency: 1.5GHz ⇒ 3GHz High Thickness Accuracy(PA, Filter ,etc) 4Layers ⇒ 6Layers, Higher Density Laser drill process ability

Reflow Temp: 260oC Heat Resistance(Lead Free)

Halogen Free requirement Halogen free materialAntenna of Base Station Frequency: 1.5GHz ⇒ 3GHz Dk:<3.5, Df:<0.003 LevelPhase Shifters, From Teflon & PPE boards Lower Process CostAnti crash radar on to Lower Cost Materials Drift of electric property onautomotive and etc Frequency: 24GHz ⇒ 76GHz water absorption

GeneralHigh-

Frequency

Properties (Functions)Field Application Required Properties ofBase Materials

Low Dk, Low loss & High reliability (Heat resistance, TH reliability, CAF) with good process ability

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5Requirement of Material for High-Frequency PWBs

Stripline

Propagation delay time Td = Dkc

Characteristic impedance Zo =

wtb

60Dk

4b0.67p(0.8w + t)

In

Transmission loss( a ) = Conductor loss( ac ) + Dielectric loss( ad )

ad = 27.3 Dk Dffc

Dk : dielectric constant, Df : Dissipation factor, f : Frequency, c : Light velocity

b : Dielectric layer thicknessw : Conductor widtht : Conductor thickness

Important issue in high-frequency circuits Reducing transmission loss

/ Reduction of ad Low Dk & Df Resin Technology(Excellent dielectric properties & Stable Dk &Df againstfrequency, temperature, humidity, …..)

/ Reduction of ac Original Profile-Free Conductor(High adhesion technology for very low surface roughness foil)

< Solution to Requirement >

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6

Low Dk & Low DfThermosetting resin system

(Low-polar cross-linking design)

Non-polar & Rigid Liner polymer

Semi-IPN structure resinby Original polymer alloy technologyStable Dk & Df

vs. Temperature & Humidity Low Df Inorganic filler

Filler/Resin Interface Control

Low Dk / Low Df

Low water absorption

High Tg

High heat resistanceLow water absorption

Low Dk / Low Df

Good insulation reliabilityLow DfLow CTE

Novel high performance materialNovel high performance material

< Structure model of cured new resin >< Structure model of cured new resin >Non-polar & Rigid

Linear polymer

High heat resistance

Low Dk & Low DfThermosetting resin

High Tg & High strengthHardener

Low Df Inorganic filler

Development Concept of New Resin System

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7Filler/Resin-Composite Technology(1)

Matrix resin

Aggregation

InorganicFiller

/ Increase in water absorption/ Poor heat resistance/ Poor electric insulation

and CAF restraining property

Interface Control between Filler and Resin (FICS)

Optimization of filler / resin-interfaceHigh Dispersion & Good adhesion

/ Low water absorption/ Excellent heat resistance/ Excellent electric insulationand CAF restraining property

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8Filler/Resin-Composite Technology(2)

0.0025

0.0030

0.0035

0.0040

0.0045

0.0050

0.30 0.35 0.40 0.45 0.50Water Abshorption

(mass%，after PCT-5h)

Df(1

GH

z, a

fter P

CT-

5h)

Df of the cured resin after PCT

Untreated

Optimally treated

Effect by Optimal Interface Control on Df of the Cured Resin

Good dispersion & adhesion

Filler

< Cross section of cured resin >

Water absorption (%, after PCT-5 h)

Df(

1 G

Hz)

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9General Properties of New Material

* IPC-TM-650 2.5.5.9: Capacitance method with RF Impedance/Material Analyzer (25 oC)** JPCA-TM001 A test method for copper-clad laminates for printed wiring boards dielectric constanat and dissipation factor. IPC-TM-650 2.5.5.5.1: Triplate-line resonator method with Network Analyzer (25 oC)*** Moisture treatment condition: PCT (121oC/0.22 MPa)**** TH/TH wall thickness: 0.3 mm, Condition: 85oC/85%RH, 100 V dc applied

Item Condition Unit New laminate PTFE/E-Glasssubstrate

ConventionalFR-4

Dielectric Constant (Dk) 1 GHz* - 3.50 - 3.55 2.65 - 2.70 4.10 - 4.201 GHz** - 3.40 - 3.45 2.60 - 2.65 4.00 - 4.103 GHz** - 3.40 - 3.45 2.60 - 2.65 3.95 - 4.05

Dissipation factor (Df) 1 GHz* - 0.0014 - 0.0018 0.0005 - 0.0010 0.0160 - 0.01801 GHz** - 0.0024 - 0.0028 0.0024 - 0.0028 0.0180 - 0.02003 GHz** - 0.0034 - 0.0038 0.0030 - 0.0034 0.0200 - 0.0220

Copper peel strength (18 μm) Standard (Rz: 5-7 μm) 0.7 - 0.9 1.3 - 1.4 1.4 - 1.6VLP (Rz: 3-4 μm) kN/m 0.6 - 0.7 - -

PF (Rz: 1 μm) 0.7 - 0.8 - -Glass transition temperature (Tg) TMA oC 175 - 185 20 - 25 120 - 130CTE xy 14 - 15 17 14 - 17

z1 ppm/oC 48 - 55 100 - 110 50 - 70z2 100 - 130 290 - 320 240 - 310

Heat resistance (T-288) IPC-TM-650 2.4.24.1 min > 60 - < 3Heat resistance PCT***-3 h - Good Good NG(288 oC/20 s dipping) PCT***-5 h - Good Good NGWater absorption PCT***-5 h % 0.20 - 0.30 0.01 - 0.02 1.0 - 1.2CAF restraining property**** - h > 1000 - > 1000Flammability UL-94 - V-0 V-0 V-0

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10Feature concerning Dk & Df of new material

0

0.005

0.010

0.015

0.020

0.025

50 55 60 65 70 75 80 85 90

Resin Content(vol%)

Df(1

GH

z)

2.8

3.0

3.2

3.4

3.6

3.8

4.0

4.2

4.4

50 55 60 65 70 75 80 85 90

Resin Content(vol%)

Dk(

1GH

z)

Relationship between Dk&Df and resin content of laminates＜ Measurement Conditions ＞/ Method：Triplate-Line Resonator by Vector Network Analyzer (JPCA tm001/IPC-TM-650_2.5.5.5.1)/ Temperature & Humidity：25 ℃/ 60%RH/ Laminate Thickness：1.6mm(Signal/Ground: 800μm apart), Copper foil：18μm/ Signal Conductor Line Width：1mm(Zo: ca. 50Ω)

Current Low DkNew Laminate

Conventional FR-4

Low Dk Epoxy

Current Low Dk

New Laminate

Conventional FR-4

Low Dk Epoxy

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11

< Measurement Conditions >/ Method:Triplate-Line Resonator by Vector Network Analyzer/JPCA TM001/IPC-TM-650_2.5.5.5.1/ Temperature & Humidity: 25 oC/ 60 %RH/ Laminate Thickness: 0.8 mm(Signal-Ground Distance: 0.8 mm), Copper foil:18 μm/ Signal Conductor Line Width: 1 mm

Dielectric Properties (vs. Frequency)

2.5

3.0

3.5

4.0

4.5

0 2 4 6 8 10Frequency (GHz)

Dk

Conventional FR-4

New laminate

PTFE/E-glass

0

0.005

0.010

0.015

0.020

0.025

0 2 4 6 8 10

Frequency (GHz)

Df

Conventional FR-4

New laminate

PTFE/E-glass

Good stability of dielectric properties in wide frequency bands

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12

0

0.005

0.010

0.015

0.020

0.025

0.030

0 1 2 3 4 5

PCT-Treating Time (h)

Df (

1 G

Hz)

3.03.23.43.63.84.04.24.44.64.85.0

0 1 2 3 4 5

PCT-Treating Time (h)

Dk

(1 G

Hz)

Dielectric Properties (vs. Moisture Absorption)

Conventional FR-4

New laminate

Conventional FR-4

New laminate

Stable Dk & Df against PCT treatment compared with FR-4

< Measurement Conditions >/ Method:Triplate-Line Resonator by Vector Network Analyzer/JPCA TM001/IPC-TM-650 2.5.5.5.1/ Moisture treatment condition: PCT(121oC/0.22 MPa)-1~5 h/ Temperature : 25 oC/ Laminate Thickness: 1.6 mm(Signal-Ground Distance: 0.8 mm), Copper foil:18 μm/ Signal Conductor Line Width: 1 mm

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13

0

0.005

0.010

0.015

0.020

0.025

0.030

-40 -20 0 20 40 60 80 100

Temperature (℃)

Df (

1 G

Hz)

3.0

3.2

3.4

3.6

3.8

4.0

4.2

4.4

-40 -20 0 20 40 60 80 100

Temperature (℃)

Dk

(1 G

Hz)

Dielectric Properties (vs. Temperature)

New laminate

Conventional FR-4 Conventional FR-4

New laminate

Good stability of dielectric properties against temperature

< Measurement Conditions >/ Method:Triplate-Line Resonator by Vector Network Analyzer/JPCA TM001/IPC-TM-650 2.5.5.5.1/ Temperature: -30~90oC/ Laminate Thickness: 1.6 mm(Signal-Ground Distance: 0.8 mm), Copper foil:18 μm/ Signal Conductor Line Width: 1 mm

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14

0

0.1

0.2

0.3

0.4

0.5

0.6

0.7

0.8

0 200 400 600 800 1000 1200

Treatment Time (h)W

ater

Abs

orpt

ion

(%)

0

0.2

0.4

0.6

0.8

1.0

1.2

0 1 2 3 4 5 6

Treatment Time (h)

Wat

er A

bsor

ptio

n (%

)Water Absorption

PCT(121oC/ 0.22 MPa)PCT(121oC/ 0.22 MPa) 85oC/ 85%RH85oC/ 85%RH

(t0.8 mm) (t0.8 mm)

New laminate

Conventional FR-4 Conventional FR-4

New laminate

Superior low moisture absorption (Water absorption is a quarter of the values of FR-4)

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15

0

100

200

300

400

500

600

Flex

ural

Stre

ngth

(MPa

)0

5

10

15

20

25

Flex

ural

Mod

ulus

(GP

a)Mechanical Properties

Flexural ModulusFlexural Modulus Flexural StrengthFlexural Strength

25oC 200oC

Newlaminate

PTFE/E-glass

ConventionalFR-4

Newlaminate

PTFE/E-glass

ConventionalFR-4

Flexural modulus of new laminate is higher than that of PTFE laminate( Warpage during the PCB manufacturing can be decreased. )

25oC 200oC

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16

(Treating Condition: 85oC/85%RH, 100 V)

85oC/85%RH, 100 V t0.8 mm (Cu: 18 μm)

Diameter: 0.4mm

TH/TH distance: 0.3 mm

◆◆

◆◆

Insulation Reliability : Results of CAF evaluation

1.0E+06

1.0E+08

1.0E+10

1.0E+12

1.0E+14

1.0E+16

0 200 400 600 800 1000 1200

Treating time (h)

Insu

latio

n re

sist

ance

(ohm

)

Conventional FR-4

New laminate

Good CAF restraining property

< Conditions >

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17

-10

0

10

20

30

40

50

60

70

80

0 200 400 600 800 1000

Number of cycle

Cha

nge

ratio

of e

lect

ric re

sist

ance

(%

)

TH/TH distance：0.3mm

/ Laminate: t3.0mm/18D (Plated Cu: 20 μm)

/ Test pattern: Daisy-Chain(320-Holes)

/ Pre-treatment:E-3/130 C-192/30/60

260oCmax reflow, 3cycle/ Test condition:

-65oC/30min 125oC/30min

Diameter: φ0.4mm

< Condition >

Thickness: 3.0mm

New laminate

High-Tg FR-4

TH/TH distance: 0.3 mm

The connection reliability of through-hole: Results of thermal shock test

Good through-hole connection reliability

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18

Layer counts : 28 layer boardTotal thickness : 4.1mm

Precondition:E-0.5/110 C-24/85/85%RH

Pb-free Reflow255degC X 6 times

No blister & No delaminationobserved

Dia.0.25mm Dia.0.30mm

Pb-free Heat resistance of high layer count

After reflow 255degC 10sec x 6 times

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19

Item New laminate High-Tg FR-4

Reflow*,×3Times OK OK

×6Times OK OK

×9Times OK Crack

OK Crack

288oCFloat ×10 s(after Reflow ×3)

288oCFloat/300s(after Reflow ×3)

Pb-free Heat Resistance of Sequential Lamination

< TEG Structure >

* Reflow condition: Max 250oC

< Evaluation Result >

SA: 8Layer (IVH)

SA: 8Layer (IVH)P/P X 3ply

Layer counts: 16 (8+8)Thickness: 4.2 mmInner copper: noneIVH Diameter: 0.4 mmIVH Pitch: 0.3 mmIVH-Plugging Ink: THP-100DX1IVH-Cu thickness: 15 μm

New laminate High-Tg FR-4

Crack

Item

After Reflow 3 Times

Reflow 3 Times +

288oC Float 300 s

< Cross section photograph >

New laminate

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20IST result after Pb-free

Layer counts : 24 layers PCB thickness : 3.1 mmTest temp.: 150oC +/- 3oC in 3 minutesCriteria of failure: more than 10% change of resistance

Drill hole size Pre-conditioning Cycles

0.010” AS IS > 1,000

4X (260oC) > 1,000

6X (260oC) > 1,000

0.0135” AS IS > 1,000

4X (260oC) > 1,000

6X (260oC) > 1,000n = 6pnl

Good through-hole connection reliability

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21

Table1. Example for drilling conditionDiameter of drill bits

ItemØ0.25mm Ø0.6mm

Thickness 4.4mm (16 Layers)MCV L188B UV J293BDrill bits

(Union tool) Point angle 130º, Helix angle 45º, Undercut typeEntry board LE-400 (Aluminum: 100um, resin:100um)

Stacked panel 1 boardRevolution number 100,000 rpm 60,000 rpm

Feed rate1.0m/min.10µm/rev

1.05m/min.17.5µm/rev

Life of drill bits about 1,000 hits

dia. 0.25mm dia. 0.6mm

There is no smear.

Drilling process ability

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22

1. Desmear conditions

Prscess Chemicals Temp. (oC)

Time (min.)

SwellingMLB conditioner 211

80 5

EtchingMLB promoter 213

80 10

Neutrali-zation

MLB neutralizer 216-2

RT 5

Thickness: t0.8 Size: 50mm X 50mm without coppper, n=5

New Laminate has a high desmear rate compared with High-Tg FR-4. Possible to reduce its desmear process time in comparison with that of High Tg FR-4

0

0.20

0.40

0.60

0.80

1.00

1.20

1.40

FX-II High-Tg FR-4

Wei

ght c

hang

e (m

g/cm

2) 1 time2 time3 time

Desmear rate

New Laminate

2. Sample

High Tg FR-4

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23Profile-free Copper Foil

Standard Cu Foil Low profile Cu Foil Profile-free Cu FoilRz = 8.0 μm Rz = 3.0 μm Rz = 1.2 μm

Current Cu Foils need roughening treatment on its surface for keeping enough peel strength.

5.0um5.0um5.0um

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24Adhesive Property

Base material : Filled high Tg

Rz:7-8μm

Rz:2.7-3.3μm

Rz:1.1-1.5μm

StandardCu Foil

Peel

Str

engt

h (k

N/m

)

0.6

1.2

1.0

0.8

0.4

0.2

0

Rz:1.1-1.5μm

Low profileCu Foil

Profile-freeCu Foil itself

Newly DevelopedProfile-free Cu Foil

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25

Standard Cu Foil Low Profile Cu Foil Profile-free Cu Foil

Ferric chloride etchant

Top

Bottom

EtchingConveyer Speed 1.0 x1.2 x 1.4Improvement in the speed of an etching line is possible with profile-free Cu foil.

L/S:30/30μm 18μm Cu Foil

Circuit Formation

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26Evaluation Technology(High-Frequency Performance of PWBs)

●

●

< Contents of Evaluation >(1) Propagation delay time (2) Transmission Loss (3) Eye Pattern Diagram

< Specifications of Testing Board >/ Size: 510 mm X 510 mm/ Layer Count: 8 Layers/ Line Structure: Strip-line/ Dimension Parameters

Line-Width: 0.06 ~ 0.184 mmDielectric Thickness(G/G): 0.16 ~ 0.40 mmConductor Thickness: 12, 18, 35, 70 μmLine-Length: 500 mm

/ Connector: SMA(φ3.5 mm)/ Connection(SMA/TH): Solder joint

Layer structure

Core

PrepregGround(G)

Ground(G)

Ground(G)

Ground(G)Signal Line(S-a)

Signal Line(S-b)

Signal Line(S-a, 500 mm)SMA Connector

Line Layout

●

●

Signal Line(S-b,500 mm)

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27

5.8

6.0

6.2

6.4

6.6

6.8

7.0

7.2

7.4

0 1 2 3 4 5 6

伝搬

遅延

時間

（ns/

m）

周波数（GHz）

Propagation delay time

< Measurement Conditions >/ Characteristic Impedance: 50 Ω/ Temperature & Humidity: 25oC/60%RH/ Inner Layer Surface Treatment:

Reduction Treatment

< Evaluation System >

V-NA

Testing Board

wb t

/ Line-Width(w): 0.124 mm (FR-4: 0.11 mm)/ Dielectric Thickness(b): 0.26 mm/ Copper Thickness(t): 18 μm

< Dimensional Parameters >

New laminate

Conventional FR-4

Frequency

Pro

paga

tion

dela

y tim

e (n

s/m

)

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28

-40

-35

-30

-25

-20

-15

-10

-5

00 1 2 3 4 5 6

Frequency (GHz)

Tran

smis

sion

loss

(dB

/m)

Transmission Loss（S-Parameter(S21)）

wb t

/ Line-Width(w): 0.124 - 0.138 mm/ Dielectric Thickness(b): 0.26 mm/ Copper Thickness(t): 18 μm

< Dimensional Parameters >

< Evaluation System >

V-NA

Testing BoardConventional FR-4

New laminate(VLP foil)

New laminate(Profile-free foil)

< Measurement Conditions >/ Characteristic Impedance: 50 Ω/ Temperature & Humidity: 25oC/60%RH/ Inner Layer Surface Treatment:

Reduction Treatment

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29

< Measurement Conditions >/ Evaluation PWB: Strip-Line Structure/ Input Pulse(Bit rate): 5 Gbps/ Temperature & Humidity: 25oC/60%RH/ Characteristic Impedance: 50 Ω/ Connection: Though Hole-SMA (by Solder)/ Inner Layer Surface Treatment: Reduction Treatment

< Evaluation System >

wb t

/ Line-Width(w): 0.114~0.144 mm/ Dielectric Thickness(b): 0.26 mm/ Copper Thickness(t): 18 μm/ Line-Length: 500 mm

Testing Board

Pulse Generator

Oscilloscope

< Dimension Parameters >

New laminate (VLP) New laminate (Profile-free)

Conventional FR-4

50ps/div 100mV/div

50ps/div 100mV/div 50ps/div 100mV/div

Eye Pattern Diagrams

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30

Df(1

GH

z)Dk(1GHz)

0.0020

0.0040

0.0060

0.0080

0.0100

0.0120

0.0140

0.0160

0.0180

0.0200

0.0220

0.0240

04.4 4.3 4.2 4.1 4.0 3.9 3.8 3.7 3.6 3.5 3.4 3.3 3.2 3.1 3.0 2.9 2.8

Standard FR4

High Tg FR-4

Filled High Tg

Teflon GradeNew Laminate

※ JPCA TM001/IPC TM650 2.5.5.5.1/IEC61189-2-720(TBD)

Property map of high frequency materials

Under Development

HighHigh--End GradeEnd GradeDkDk 3.7 / 3.7 / DfDf 0.0070.007JPCAJPCA--HCL01/21HCL01/21IEC 61249IEC 61249--22--32/3432/34

MiddleMiddle--Range GradeRange GradeDkDk 4.1 / 4.1 / DfDf 0.0170.017JPCAJPCA--HCL02/22HCL02/22IEC 61249IEC 61249--22--31/3331/33

Halogen-free Middle

Halogen-free High-end

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31Conclusions

(1) We have developed the filler dispersion technology and the resinwhose dielectric properties and heat resistance are excellent. The laminate with these technologies showed almost the same level of low dissipation factor (Df) as the PTFE laminate at high frequency signal (3GHz).

(2) The laminate also showed the excellent properties such as low moisture absorption, high CAF resistance and high Tg enough to obtain the heat resistance for lead-free soldering process.

(3) The newly developed laminate is suitable for application in the PWBs for various high speed and high frequency uses, such as high-end server, router, measuring equipment, super computer, RF module and antenna.

Note: The contents of this report are based on the results of experiments and do not represent a guarantee of the values for each property.