Current development status of

Auto-catalytic Silver bath

Uyemura Advanced Surface Finish

1

台灣上村研發部 蕭智遠

Overview

LED market analysis

Introduction for Ag

ENES/ENEPES Process

The future of FC

Summary

2

LED market analysis

Introduction for Ag

ENES/ENEPES Process

The future of FC

Summary

3

Overview

LED lighting to dominate LED applications after 2014

Penetration of LED applications

Reference: Digtimes,2012

4

LED market analysis

Introduction for Ag

ENES/ENEPES Process

The future of FC

Summary

5

Overview

• Advantage of Ag plating

Introduction

High reflection

High speed application

• Skin effect

2

ρ: Resistivity of conductor

ω:angular frequency (2πf)

μ: absolute permeability

δ: Skin depth

63% signal contained!

Ag has the lowest resistivity

μ=4π×10-7(亨利/公尺)

Reference: National Central University

0

10

20

30

40

50

60

70

80

90

100

350 400 450 500 550 600 650 700 750

refl

ect

ion

rat

e(%

)

Wave length(nm)

AgCuAuPdNi

Thermal conductivity (20℃) (w・m-1・k-1) Electrical resistivity (300K) (n Ω・m)

Ag Au Cu Ni Pd

429 318 401 91 72

Ag Au Cu Ni Pd

15.9 22.1 16.8 69.3 105.4

6

LED market analysis

Introduction for Ag

ENES/ENEPES Process

The future of FC

Summary

7

Overview

Advantages of ENES

No discolor by heat treatment

For applications of the eutectic gold-tin alloy

Good mechanical properties

Good coverage as normal ENIG

Solder joint reliability is good

Reflection rate

Reflection rate >95% at visible light

Wire bonding

Wire bonding be used when Ag thickness >0.4um

8

Process Temp.(oC) Plating con.

Cleaner 50 5 min

Micro Etching 30 1 min

Acid Rinse R.T. 1 min

Pre-dip R.T. 1 min

Activator R.T. 1 min

Post dip R.T. 1 min

EL-Ni 80 3-5 um

Activator 50 1 min

EL-Ag 40 0.2-1.5 um

Anti-tarnish 50 1min

Uyemura ENES Process

It is necessary to rinse after each process, except for pre-dip.

The condition of cleaner and post-dip could be adjusted for different substrates.

The thickness of EL-Ni and EL-Ag could be applied for reliability test and reflection rate.

Cu

Activated Pd

Cu Cu

Ni Ag Ni

9

Ni：5um, Ag:0.4-0.8um

KONICA MINOLTA CM-3700d, di:8°, SCI, SAV(3×5mm)

1 2 3

5

1:1 1:10 1:100

Big Pad

4 Small pad

0.32 0.29 0.31 0.30 0.30

4.87 4.92 5.02 4.85 4.90

0.001

0.01

0.1

1

10

1 2 3 4 5

Ag Ni

1min

3min

5min

As-plate

350 400 450 500 550 600 650 700 750

50

55

60

65

70

75

80

85

90

95

100

Reflection rate

Uniform Thx.

Discolor checking

350oC for 5min

Uniform of Ag thickness as

plating.

There are no significant

discolor after heat treatment

Retard Ni diffusion

Reflection rate > 95%

The number of point

10

Characters of ENES

Wavelength (nm)

Ref

lect

ion r

ate

(%)

Cu

Ni(P)

Ni(P)

Cu

Ni(P)

Cu

Ni(P)

Ni(P)

Cu

Ni(P)

Ni(P)

Cu

Cu

Ni(P)

0.2 μm Ag

5 μm 5 μm

5 μm 5 μm 5 μm

1 reflow

3 reflow

SAC305

0.4 μm Ag 0.8 μm Ag

• No Detachment of IMC are

observed after 3 times reflow.

Cu

Ni(P)

(Cu,Ni)6Sn5

SAC 305

Cu

Ni(P)

(Ni,Cu)3Sn4

SAC 305

(Cu,Ni)6Sn5

Non-spalling Spalling

IMC determination

Cu

Ni(P)

11

SAC305 SAC305

Requirement for ENEPES process

Retard Ni

diffusion to

Ag layer

Reflection

rate

Solder joint

reliability

Wire bonding

reliability

12

solder layer Al substrate PCB

Ag plating 3.2 mm

19 mm

2.2 mm

1.65 mm

0.5 mm

Ag plating

1 2 3 4

Process Temp.(oC) Plating con.

Cleaner 50 5 min

Micro Etching 30 1 min

Acid Rinse R.T. 1 min

Pre-dip R.T. 1 min

Activator R.T. 1 min

Post dip R.T. 1 min

EL-Ni 80 3-5 um

EL-Pd 50 0.02-0.1 um

EL-Ag 40 0.2-1.5 um

Anti-tarnish 50 1min

Uyemura ENEPES Process

Cu

Activated Pd

Cu Cu

Ni Pd Ag

Ni

It is necessary to rinse after each process, except for pre-dip.

The condition of cleaner and post-dip could be adjusted for different substrates.

The dipping time of EL-Ni, EL-Pd and EL-Ag could be adjusted for required thickness. 13

Relation of heat treatment and Ni diffusion

0

5000

10000

15000

20000

0 200 400 600 800

Inte

nsi

ty

Depth(nm)

Pd

Ag

Ni

0

5000

10000

15000

20000

0 200 400 600 800

Inte

nsi

ty

Depth(nm)

Pd

Ag

Ni

0

5000

10000

15000

20000

0 200 400 600 800

Inte

nsi

ty

Depth(nm)

Pd

Ag

Ni

0

5000

10000

15000

20000

0 200 400 600 800

Inte

nsi

ty

Depth(nm)

Pd

Ag

Ni

ENEPES =5/0.02/0.2um

No heated ENEPES =5/0.02/0.8um

No heated

ENEPES =5/0.02/0.2um

Heated (300 deg C-30min.)

ENEPES =5/0.02/0.8um

Heated (300 deg C-30min.)

ENEPES can retard the diffusion of Ni into the Ag layer after heat treatment . 14

No

Heated

Heated

Ag:0.8um Ag:0.2um

15

Reflection rate

As-plate

Ni：5um, Pd:0.03um, Ag:0.2-1.5um

KONICA MINOLTA CM-3700d, di:8°, SCI, SAV(3×5mm)

50

55

60

65

70

75

80

85

90

95

100

350 450 550 650 750

refle

ctio

n ra

te(%

)

Wavelength(nm)

NPR-4(6um)/as-plate

0.2um

0.5um

0.8um

1.2um

1.5um

We are considering that it is necessary to be over 0.2 um for reflection rate.

When Ag thickness is thicker, the reflection is increased at visible light.

Solder joint reliability

Reflow1

0.2um 0.3um 0.4um 0.5um 0.8um

Ball pull no significant differences (~2183g)

Ball shear no significant differences (~927g)

HSBS no significant differences (~1327g)

Reflow3

0.2um 0.3um 0.4um 0.5um 0.8um

Ball pull no significant differences (~2131g)

Ball shear no significant differences (~913g)

HSBS no significant differences (~1213g)

Reflow5

0.2um 0.3um 0.4um 0.5um 0.8um

Ball pull no significant differences (~2055g)

Ball shear no significant differences (~902g)

HSBS no significant differences (~1131g)

It is recommended that Ag > 0.2 um for good solder joint.

solder ball: SAC305(diameter:500um)

Ball shear strength is the average of 15 points. (shear speed: 170 um/s)

HSBS strength is the average of 15 points. (shear speed: 1 m/s) (Dage 4000-Schmidt)

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Wire bonding reliability

Pull

point

A

B C

D

E

Pull speed: 170um/sec

It is possible to bond on ENEPES by

optimizing the thickness of Ag.

K&S 4700AD

Good bonding

0%

20%

40%

60%

80%

100%

0.2um 0.3um 0.4um 0.5um 0.2um 0.3um 0.4um 0.5um

RSD-4 ENIG ENEPIG RSD-4 ENIG ENEPIG

as-plate 175deg.C-16hr

Fa

ilure

mo

de

A B C D E

8.7 9.2

8.1 8.2

2.7

10.0

6.5 6.4 6.7 7.3

0.0

8.3

0

2

4

6

8

10

12

14

Pu

ll str

en

gth

(g

)

Average

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LED market analysis

Introduction for Ag

ENES/ENEPES Process

The future of FC

Summary

18

Overview

Road map of Flip Chip

19

Reference: Amkor TMV - Practical Components

27.3 28.1

27.6

0.1

0.1

SAC305 Sn0.7Cu

Sn Ag Cu

Sn : Ag : Cu= 0.283 : 9.187 : 0.107 (Dollars(USA)/g)

reference:鉅亨網期貨(2012,9,4)

Cost Issue

The Ratio of Gold and Silver Sn07Cu Solder replaces for

SAC305 on FC(C4 zone)

(Dollars(USA)/particle)

20

About final finish type :

Ag replace Au Cost down≒97% of gold

(the same thickness)

≒ 1600Dollars(USA)/OZ

≒30Dollars(USA)/OZ

Ref: T.Y. Lee, W.J. Choi, and K.N. Tu ”

Morphology, kinetics, and thermodynamics of

solid-state aging of eutectic SnPb and Pb-free

solders (Sn–3.5Ag,Sn–3.8Ag–0.7Cu and Sn–0.7Cu)

on Cu “J. Mater. Res., Vol. 17, No. 2, Feb 2002

Phase diagram of Sn–Ag–Cu

SAC305

More Ag addition

Ag concentration in solder

Plate-type

21

Ag concentration in solder

Ag

4-2434

Ag

-424

Ag/solder

ρ10X)107.53π(])10π[(37.53

4

ρ10X)105.37π(C

Solder type SAC305 Sn0.7Cu

Critical Ag thickness (μm) 0.18 μm 1.27 μm

Critical CAg/solder 0.5% 3.5%

• The effect of electroless Ag thickness : Solder

Pd Cu Ni

Ag

75 μm

75 μm

Cu X μm

According to Ag concentration in solder, the critical Ag thickness is only 0.18um

for SAC305, but 1.27um for Sn0.7Cu.

CAg/solder: Concentration of Ag in solder(wt.%) ρ : density of SAC305 7.4 (g/cm3), density of Sn0.7Cu 7.3 (g/cm3) ρAg : density of Ag 10.49 (g/cm3) X: thickness of Ag (μm)

22

LED market analysis

Introduction for Ag

ENES/ENEPES Process

The future of FC

Summary

23

Overview

ENES ENEPES

Advantages

No discolor by heat treatment

Solder joint is good

Reflection rate

W/B

Retard Ni diffusion

Solder joint is excellent

Reflection rate

W/B

Drawbacks

IMC become spalling until 5

reflow

Can’t W/B if Ag is thinner

than 0.4 um

So far so good

Thickness Ni 3-5 um

Ag 0.2-1.5 um

Ni 3-5 um

Pd 0.02-0.1 um

Ag 0.2-1.5 um

Comprehensive

estimate

Cu

Ni-P

Ag

Cu

Ni-P Pd-P Ag

Summary Comparison of each process

24

Reliability

Reflection

Cost DownUniform

Thx.

Retard Ni

Diffusion

Reliability

Reflection

Cost DownUniform

Thx.

Retard Ni

Diffusion

Thank you for your attention

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