High Density and Low Cost Approachfor the PCB of semiconductor tester

Takehisa SakuraiHitachi Chemical Co. America, Ltd.

Masahiro KatoHitachi Chemical Co. Ltd.

Contents

1. Technical trend for PCB2. MWB technology3. Hybrid MWB for advanced PCB4. Summary

2

Technical trend for testing

Speed of electric device is getting higher

・ High Density ;

・ High Speed ;

3

More signal is required- increasing in Pin count- Pair drive for High speed signal

Testing system becomes complicated andvarious components to be required

- pin count of comps. increased and pin pitchbecome narrow due to comps. downsizing

・ Fine Pattern ;

Conflicting PCB Requirements

4

High Speed

High Density

LowerCost

Trace width

Material

Finepattern

Suitable for MWB Suitable for HDI P/E

Suitable for standard P/E

Routing density / Pin

Yield

*MWB is a PCB which replaces etched signaltraces with copper wires

*Signal lines are able tocross over each otherbecause copper wire isinsulated with resin coating.

MWB technology

X-section

Adhesive Layer

Insulation Layer(Polyimide)

Conductor Wire (Cu)

5

Actual wiring operation

6

Print and Etch (P/E) MWB

Signal LayerCAM Image

Index # of signalsper layer

12.5

* Average based on achievements(convert fm P/E to MW)

Multi-Wire has abilities to,- Route 2.5 times of signals than P/E PCB into one layer.- Increase total # of routed signals in PCB.

7

High Density Wiring

~ 500 DUT ~750 DUT ~ 1500 DUT~ 1000 DUT

MWB - High signal capacity

3k 6k 9k 12k 15k 18k 21k

24 (34)

30 (45)

36 (56)

42 (67)

48 (78)

MWB (P/E)

54 (89)

Laye

r Cou

nt

# of Signal Nets24k

60 (100)

0.065 wire

0.080 wireP/E

8

1.25mm 1.25mm

1.0mm1.0mm

Based on Achievements for Probe Card PCB

Item Unit P/E0.5oz HVLP MWB

Material - FX-2(s) Dk3.6

I-671Dk3.6*

PCB Thickness mm 6.2Drill Dia. (Dh) mm 0.25Pad Dia. (Dp) mm 0.40 -Line width (L) mm 0.080 0.065Space L-L (SL) mm 0.080 0.113Space P-L (SP) mm 0.080 -

Resistance Ω/m 11.9 5.3Crosstalk % 9.8 2.5

Attenuation@3GHz dB -4.9 -4.6

Dh L

SlSpDp

0.8

9

Design study for pair drive (1)

* Nominal value for MWB structure

Print and Etch (P/E)

10um

Multi-Wire (MW)Formed by Die DrawingFormed by Etching Process

Comparison of Signal Shape

Diamond Die

10um

P/E0.08mm, 0.5oz Compared item MW

0.065mm

1X-section size index

Low resistance (Low attenuation) 2.3

+/- 0.010mmTolerance of Conductor Width

Easy impedance control +/- 0.003mm

~ 10umConductor Surface Roughness

Low skin effect , Low attenuationin high frequency

~ 0.5um

10

Item P/E MWBCharacteristic

impedance (Zo) Differential 100Ω Differential 100Ω

Base material FX-2(s) (Dk:3.6) I-671 (Dk:3.6*)Line width 0.080mm

0.065mmLine thickness 0.018mm

Structure

H 1.485mm 0.550mm (63% reduced)

11

Design study for pair drive (2)

MWB can reduce total thickness with keeping high routing density

H H 0.178mm0.160mm0.210mm

0.285mm

* Nominal value for MWB structure

12

P/E 0.5oz

MWB1

2

3

4

5

00.04 0.06 0.08 0.12 0.160.10 0.14

Signal Line Resistance comparison

Line width or Wire diameter (mm)

DC

Res

ista

nce

(Ω)

@ 3

00m

m

Cross-talk (Backward) Comparison

(Condition) L : 300mm, Z0 : 50Ω, Rise Time : 35psLine Pitch (mm)

Bac

kwar

d C

ross

talk

(%)

2

4

6

8

10

0100 150 200 250

P/E 0.5oz

MWB Φ0.065

13

Attenuation = Dielectric Loss (Dk, Df) + Conductor Loss (Re)

Cu Foil type

Material

Trace

Mid-RangeHE-679G

FR4E-679

High-endFX-2(s)

Line width = 0.08mm, 0.5oz Foil Wire diameter = 0.065mmStandard VLP HVLP

0

-2

-4

-6

-8

-10Atte

nuat

ion@

3GH

z, d

B/3

00m

m3GHz Signal attenuation

14

P/E

Dielectric LossConductor Loss

MWB

StandardI-671MWB

Mid-RangeHE-679G

MWB

High-endFX-2(s)MWB

Summary of MWB technology• Signal Density per layer of MWB is 2.5 times

higher than P/E PCB by using cross over wires.

• Low resistance, Low crosstalk characteristics of MWB bring better signal integrity for high speed application.

• Compared with P/E PCB, MWB can reduce a insulation thickness with keeping high density routing and high electrical performance.

15

Hybrid MWB for advanced PCB

16

Routing density / Pin

Target for Hybrid MWB

17

High Speed

High Density

LowerCost

Finepattern

Suitable for MWB

Suitable for standard P/E

Trace width

Material

Yield

GOAL:Bridge the gap

between conflicting PCB

requirements with the

development of Hybrid MWB

Suitable for HDI P/E

Application field for Hybrid MWB

Super High-endProbe card

10

20

30

40

50

100

High-endTester, Probe card, Server

Tester, Server, Router

100 8075

65 50

Laye

r cou

nt

Line width (μm)

MWB + P/E

P/E PCB+ Material Hybrid

Advanced MWB

18

Target area for Hybrid MWB

19Signal Capacity Index

100

125

150

100 200 300

Cos

t Ind

ex

P/E**

150 250

MWB

MWB + P/E

175A-MWB*

** Print and Etch PCB with Low Dk,Df material* Advanced MWB

Material Hybrid

SignalCore：FX-2(S)Prepreg:E-679

Power/GNDCore：E-679Prepreg:E-679

-25

-20

-15

-10

-5

0 1 2 3 4 5 6

Core ： FX-2(S)Prepreg ：E-679

Core ：HE-679GPrepreg ：HE-679G

Core ：E-679Prepreg ：E-679

20

Power/GNDCore：E-679Prepreg:E-679

Frequency, GHz

Atte

nuat

ion,

dB

• Lower Dk, Df material for high speed signal layers• Conventional FR-4 (high Dk, Df) for Power / GND layers

• MW for critical signals (high speed, shortest, equal length, etc.)• P/E for other signal layers (DC signal, etc.)• P/E for Power / GND layers

MWB + P/E Hybrid (e.g. 1)

Layer Type MWBMWB + P/E Hybrid

e.g. 1

Power/GND

I-671 E-679

CriticalSignal

2L - ＭＷ

I-671

2L - ＭＷ

I-671 orHE-679G or

FX-2(s)

OtherSignal

4L- ＭＷ

I-67110L- P/E

E-679

ＭＷ

P/E

P/E

21

Layer Type MWBMWB + P/E Hybrid

e.g. 2

Power/GND

I-671 I-671

CriticalSignal

2L - ＭＷ

I-6712 wires / pin

6L- P/EFX-2(S)

1 trace / pin

OtherSignal

4L- ＭＷ

I-6712 to 5 wires/ pin

4L- ＭＷ

I-6712 to 5 wires/pin

ＭＷ

P/E

P/E

• P/E with lower Dk, Df material for critical signals• Wider trace (lower density routing) is also applicable to

improve electrical performance. -> Routing density decreases, However, MWB can cover it.

22

MWB + P/E Hybrid (e.g. 2)

P/E Unit MW unit

・P/E unit and MW unit Lamination

・Drilling・Plating・Outer Layer Formation・Resist and Screen Printing・External form processing・Inspection

Enlargeof wire joint

Hybrid MWB process flow

Power/GND Signal

23

Each unit have different CTE (Coefficient of Thermal Expansion) .Key technologies which control CTE-related problem are required.

InsulatedWire

Key tech. (1) - Optimized stack up -Concern : Bow / TwistKey tech.: Optimized (Symmetrical) stack up

MW unit

MW unit

MW unit

P/E

P/E

MW unit

P/E

P/E

MW unit

MW unit

P/E2

P/E1

P/E2

24

MWB MWB + P/E (e.g.1) MWB + P/E (e.g.2)

- Throwing Power *

Key tech. (2) - Electroless Cu Plating -

ElectrolyticΦ0.30

ElectrolessΦ0.30

A

B

Electroless Electrolyticｔ 2.4 ｔ 4.3 ｔ 2.4 ｔ 4.3

60

70

80

90

100

Thro

win

g P

ower

,%

Φ0.20 Φ0.25 Φ0.30 Φ0.70

*Throwing power ＝Plating thickness in the hole (B) / Plating thickness on the surface (A)25

Concern : Plated through hole reliability Key tech.: Uniform (High throwing power) plating by electroless Cu plating

Reliability for Hybrid PCBs

26

Hybrid MWB with electroless Cu plating has good reliability.Test condition: 125 /30min. ⇔ -65 /30min.PCB thickness : t6.35mm，Drill Diameter : Φ0.30mm

Res

ista

nce

Cha

nge

Rat

io, %

Number of Test Cycle

0 100 200 300

-10

10

02468

-8-6-4-2

Upper Limitation

Lower Limitation

FX-2(s)+ E679 Hybrid

MWB + P/E Hybrid

“A-MWB” Further advanced approach

MWB

Example for Sub Unit

Item e.g. 1 e.g. 2

PCBType

P/E HDI or P/E（Pitch converter）

ＭＷＢ

FeatureAssembly for Narrow Pitch

Comps.

Further more High Density

27

SubUnit

- Assembly for Narrow Pitch Comps. - Further more High Density ( Addition of DUT count )

Summary- Application of MWB provides one of the best

solution for Higher density and Higher speed PCB.

28

- Hybrid PCB technology provides advancedcharacteristics.

MWB + P/E Hybrid structure providescost- effective solution.

A-MWB Hybrid structure is a further advancedapproach for super high density PCB.

Thank You!

29