14-11-2005 TRFA Annual meeting, Florida, USA 1 Novel halogen free epoxy resin for high performance electronic applications P.K.Dubey, Dr. Hitesh Soni*,

14-11-2005 TRFA Annual meeting, Florida, USA 1

Novel halogen free epoxy resin for high performance electronic applications

P.K.Dubey, Dr. Hitesh Soni*, Dr. M.Soni, Ms. Thipa

Thai Organics Chemicals Co., Ltd. (Epoxy Division)Map Ta Phut-Rayong (Thailand)


Introduction:

PWB, flip chip encapsulation, surface mounting adhesives, conformal and die coatings are major applications requiring FR epoxy resin

Demand of halogen free fire retardant material due to environmental issues

Lead free soldering calling for high heat resistance

Miniaturization of electronic components requiring high thermal stability


Conventional FR epoxy resinsBromine containing

Standard for many years and have environmental and thermal stability issue

Filler containing

Capable to achieve V-0 rating

Problem of high viscosity, aggregation of filler and micro structural defects in cured resin

Red phosphorous

Suitable to achieve V-0 rating but have issue of pigmentation & handling

Phosphorous additives

Effective fire-retardants.

Problem of high water affinity, risk of p-o-p or c-o-p bonds under humid

condition along with low thermal stability


Mechanism of various flame retardant action

R-H + •X R• + HX

HX + •OH H2O + •X

Al(OH)3xH20 Al2O3 + H2O

Px H3POX

H3POX + CH2–CH2 – H3PO4 + C- H2O

1. Halogen based flame retardant

2. Filler based flame retandant

3. Phosphorus based flame retardant


Present work

Reactive phosphorous compound (DOPO) selected for study as fire-retardant

Multifunctional EOCN and EBPN resins synthesized and suitably reacted with DOPO

Phenolic compounds based on phenol Novolac, bis-phenol Novolac, O-cresol Novolac, and tris-phenols are selected as hardener.

2MI and TPP are used as catalyst

All sets of combinations studied for thermal, mechanical, and electrical

properties.


Epoxy Resin: YDBN 602 and YDBN 602P

CH2 CH CH2

OX = A or B

A =

CH2 CH CH2

OH

P

O

O

B =

CH2

O O

OO

C CH3H3C

O O

OO

C CH3H3C

O O

OO

C CH3H3C

P O

HOCH2

DOPO

+

Epoxy Bisphenol-A Novolac (YDBN 602)

n

CH2

OX

OX

C CH3H3C

OX

OX

C CH3H3C

OX

OX

C CH3H3C

CH2

n

YDBN 602P


Epoxy resin TOCN 4030 and TOCN 4030P

H3C

O O

H3C

O O

H3C

O O

P O

HO

CH2CH2

DOPO

n

+

Epoxy Cresol Novolac (TOCN 4030)

H3C

OX

H3C

OX

H3C

OX

CH2CH2

n

TOCN 4030PCH2 CH CH2

OX = A or B

A =

CH2 CH CH2

OH

P

O

O

B =


Phenolic Hardeners:

Phenol Novolac-PN O-Cresol Novolac- OCN

BPA Novolac- BPNTris- Phenol- TP

OH OH

CH2

OH

CH2

Phenol Novolac

n

OH

H3C

OH

H3C

CH2

OH

H3C

CH2

O-Cresol Novolac

n

C

H

HO OH

OH

Triphenol

CH2

OH

OH

C CH3H3C

OH

OH

C CH3H3C

OH

OH

C CH3H3C

CH2

Bisphenol-A Novolac

n


Catalyst

2- Methyl Imidazole- 2MI Triphenyl Phosphine- TPP

N NH

CH3

2 Methyl Imidazole

P

TPP


Reaction Mechanism of 2-MI with epoxy group

Source: Farkas, A., Strohem, P.F., J.Appl. Polym. Sci., 1968, 12, p159

N N

CH3

CH2 CH

OH

CH2

ORN N

CH3

CH CH2

O

CH2

RO

CH CH2

O

CH2

RO

N N+ CH2 CH

OH

CH2

ORCH2

CH

CH2

RO

O-

N+ N CH2 CH

O-

CH2

ORCH2

CH

CH2

RO

OH

+

Alkoxide ion


mechanism of reaction between epoxy and phenol using TPP as catalyst

Romanchick, W.A., Sohn, J.E., and Geibel, J.F., ACS Symposium Series 221-Epoxy Resin Chemistry II ( Ed: R.S.Bauer) American Chemical Society, Washington, D.C. 1982, p-85

OHHC CH2

O

R HC CH2

-O

R

+PPh3

O CH2

CH

OH

R -OHC CH2

HO

R

+PPh3

Ph3POR CH

CH2HC CH2

-O

R

+PPh3

HC CH2

O

R

PPh3

+ : PPh3 +

+

+ : PPh3

Decomposition of PPh3 in absence of epoxy and phenolic group

+


Basic Properties of Epoxy resins


Typical properties Epoxy resins

Property TOCN 4030

YDBN 602

TOCN 4030P

YDBN 602P

Color yellow yellow yellow yellow

EEW 204 206 269 280

HyCl, ppm < 50 < 50 < 50 < 50

Ionic chlorine, ppm < 2 < 2 < 2 < 2

Total Chlorine, ppm 1099 1022 900 900

Residual ECH content, ppm

< 5 < 5 < 5 < 5

Physical properties are comparable


Property TOCN 4030

YDBN 602

TOCN 4030P

YDBN 602P

Viscosity @ 125oC 2006 1099 7160 3251

Softening point 82 72 92 83

Glass transition temperature 77 67 87 71

Phosphorus content 0 0 2.1 2.1

Mn 991 1007 1373 1130

Mw/Mn 3.00 4.57 2.55 4.28

Melt viscosity is low in case of YDBN resins in-spite of high Mw/Mn ratio.

YDBN resins has lower softening point

Typical properties Epoxy resins


Melt viscosity of YDBN 602 Vs. TOCN 4030

0

1000

2000

3000

125 150 175 200

Tempearture, oC

Visc

osity

, cPs YDBN 602

TOCN 4030


Melt viscosity of YDBN 602P Vs. TOCN 4030P

0

2000

4000

6000

8000

125 150 175 200

Temperature, oC

Visc

osity

, cPs

YDBN 602P

TOCN 4030P


Curing Behavior

of

Epoxy resins

with

Phenolic hardeners


Phenolic reactivity

8.4

8.6

8.8

9

9.2

9.4

9.6

OCN PN TP BPN

Phenolic hardener

Pe

ak

Tim

e, m

ins

TOCN 4030-2MI

OCN is fastest reactive phenolic hardener


Reactivity of YDBN 602 vs. TOCN 4030

7.5

8

8.5

9

9.5

10

OCN PN TP BPN

Phenolic hardener

Pe

ak

Tim

e, m

ins

YDBN 602-2MI

TOCN 4030-2MI

YDBN 602 is more reactive because of better structural symmetry and low melt viscosity


7

8

9

10

11

Pe

ak

Tim

e,

min

s

OCN PN TP BPN

Phenolic hardeners

Catalyst reactivity

YDBN 602-2MI

YDBN 602-TPP

2MI is more reactive compared to TPP because of alkoxide ion formation and more basicity of the 2MI catalyst


Reactivity of unmodified vs. modified resins

7

8

9

10

11

12

13

OCN PN TP BPN

Phenolic hardeners

Pe

ak

Tim

e, m

ins

YDBN 602-2MI

YDBN 602P-2MI

Modified resins are lower in reactivity due to the presence of acidic Phosphorus compounds.


Possible reaction of Phosphorus Resin with Catalyst

H3C

O

H3C

OX

H3C

OX

CH2CH2

CH2

CH

CH2

HO

P OO

n

+

2-methyl imidazole

N

NH

H3C

N

N

H3C

H3C

O

H3C

OX

H3C

OX

CH2CH2

CH2

CH

CH2

HO

P+ OO

n

Ring cleavagepolymerization


Gel time of YDBN 602 and TOCN 4030 resin with phenolic harderes using 1% catalyst at 120oC

0

2

4

6

8

10

OCN PN TP BPN

Phenolic hardeners

Tim

e, m

ins YDBN 602-TPP

YDBN 602-2MI

TOCN 4030-TPP

TOCN 4030-2MI

Phenolic reactivity trend- OCN>PN>TP>BPN


Thermal Property


Effect of Catalyst Concentration on Tg

160165170175180185190195

0.5 1 2

Catalyst Concentration, %

Tg

, oC

TOCN 4030-PN-2MI

YDBN 602-PN-2MI

YDBN 602-PN-TPP

TOCN 4030-PN-TPP

Sample cured 175oC/6hrs

Concentration of catalyst effect reactivity not the final crosslink structure

2-MI system gives higher Tg than TPP system


Curing Time Vs. Tg

160

170

180

190

200

5 6 7

Curing time @175oC, Hrs

Tg

, o

C

YDBN-TPP

TOCN-TPP

YDBN-2MI

TOCN-2MI

6 hrs at 175oC is adequate curing schedule for full crosslinking YDBN system shows higher Tg compared to TOCN system


Tg of various epoxy resins with different phenolic hardeners and catalyst

135

155

175

195

215

235

YDBN 602-2MI

TOCN 4030-2MI

YDBN 602-TPP

TOCN 4030-TPP

YDBN 602P-2MI

TOCN4030P-2MI

YDBN 602P-TPP

TOCN4030P-TPP

Systems

Tg, o

C

PN

OCN

BPN

TP

TP shows highest Tg(230-235oC)

YDBN systems shows better Tg compared to TOCN system in all cases.

Modified resins shows lower Tg-due to high EEW and polarity.

Modified resins with 2MI catalyst shows Tg in range of 155-185oC depending on curing agent

Sample cured 175oC/6hrs


Flammability

And

Thermal Degradation


Effect of Phosphorus content on flammability

Phosphorus content

YDBN 602-2MI TOCN 4030 –2MI YDBN 602-TPP TOCN 4030-TPP

0 V-2 Burn V-2 Burn

0.8 V-2 with low burning time

V-2 V-2 with low burning time

V-2

1.2 V-1 V-1 with dripping V-1 V-1 with dripping

1.5 V-0 with low average burning time .

V-0 with high average burning time

V-0 with low average burning time

V-0 with high average burning time

2.0 V-0 V-O V-0 V-0

1.5% Phosphorus is adequate to get flammability rating V-O

YDBN resins shows better flammability rating compared to TOCN

TPP catalyst shows better flammability rating than 2MI


YDBN resins shows better thermal degradation stability

P- resins shows initial loss at low temperature but Tmax is higher than unmodified resins

TPP cured system shows better overall degradation stability

Thermal degradation of OCN cured system by TGA

300

350

400

450

500

TPP 2MI TPP 2MI TPP 2MI TPP 2MI

YDBN 602 TOCN 4030 YDBN 602P TOCN 4030P

System

Te

mp

era

ture

, o

C

1% loss

5% loss

10% loss

20% loss

Max Loss


0

5

10

15

20

25

TPP 2MI TPP 2MI TPP 2MI TPP 2MI

YDBN 602

TOCN4030

YDBN602P

TOCN4030P

% Char yield @700oC

% Char yield @700oC

YDBN 602 char yield is higher than TOCN 4030- better flammability.

Incorporation of phosphorus increases char yield dramatically.

TPP cured system shows better char yield than 2MI


Mechanical Property

Property YDBN 602/PN/2MI

TOCN 4030/PN/2MI

YDBN 602P/PN/2MI

TOCN 4030P/PN/2MI

Ratio 100/50/1 100/52/1 100/35/1 100/37/1

Curing Schedule 120oC/15 min, 175oC/6 hrs

120oC/15 min, 175oC/6 hrs



Glass fiber content, % 63 62 64 64

Tensile strength, Mpa 336 328 352 347

Tensile strain, % 1.54 1.61 1.63 1.36

Tensile modulus, Gpa 23.5 24.9 25.2 34.33

Flexural strength, Mpa 455 477 537 599

Flexural strain, % 1.96 2.07 2.07 1.97

Flexural modulus, Gpa 27 28 29 34

Water absorption after 8 hrs at 80oC, %

0.1042 0.0941 0.0848 0.0646


Electrical property

Property YDBN 602 TOCN 4030 YDBN 602P TOCN 4030P

Dielectric Constant at 1 MHz 4.26 3.84 4.22 4.09

Dielectric Strength(t-2mm), KV/mm

18.267 18.320 19.64 17.584

Volume resistivity ( 500V), ohm-cm

2.275x (10e-15) 1.957x(10e-15) 4.346x (10e-15) 4.60x (10e-15)


Conclusion:

1. Halogen free YDBN-P and TOCN-P resins could be material of choice where high glass

transition temperature (170-190oC) or flammability is desired for electrical and

electronics applications.

2. YDBN series of resins were found comparable to TOCN resins in terms of mechanical,

electrical and thermal properties with distinct advantage of lower melt viscosity which

could be advantageous for better wetting or lower coating thickness requirements.

3. Curing agents could be selected depending on process/ performance requirements. TP has

exhibited higher Tg with low melt viscosity where as low functionality PN could be used

for moderate Tg requirement.

4. 2MI as catalyst lead to higher Tg of cured matrix compared to TPP.


Acknowledgement:

Sincerely thanks

- Management of TOCC

- All Colleagues Somsak, Satid, Thithikan and Thaniya

- Mr. Wutti of Mettler Toledo, Thailand


Thank you


Any Question?

Documents

14-11-2005 TRFA Annual meeting, Florida, USA 1 Novel halogen free epoxy resin for high performance electronic applications P.K.Dubey, Dr. Hitesh Soni*,