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)
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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
TRFA Annual meeting, Florida, USA

3. Conventional FR epoxy resins TRFA Annual meeting, Florida, USA
Bromine 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
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Mechanism of various flame retardant action
1. Halogen based flame retardant
R-H •X R• HX
HX •OH H2O •X
2. Filler based flame retandant
Al(OH)3xH Al2O H2O
3. Phosphorus based flame retardant
Px H3POX
H3POX CH2–CH2 – H3PO C
- H2O
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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.
TRFA Annual meeting, Florida, USA

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Epoxy Resin: YDBN 602 and YDBN 602P
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Epoxy resin TOCN 4030 and TOCN 4030P
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Phenolic Hardeners:
Phenol Novolac-PN
O-Cresol Novolac- OCN
BPA Novolac- BPN
Tris- Phenol- TP
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Catalyst
2- Methyl Imidazole- 2MI
Triphenyl Phosphine- TPP
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10. Reaction Mechanism of 2-MI with epoxy group
Source: Farkas, A., Strohem, P.F., J.Appl. Polym. Sci., 1968, 12, p159
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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
TRFA Annual meeting, Florida, USA

12. Basic Properties of Epoxy resins TRFA Annual meeting, Florida, USA
Basic Property of Epoxy resins
TRFA Annual meeting, Florida, USA

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Typical properties Epoxy resins
Property
TOCN 4030
YDBN 602
TOCN 4030P
YDBN 602P
Color
yellow
EEW
204
206
269
280
HyCl, ppm
< 50
Ionic chlorine, ppm
< 2
Total Chlorine, ppm
1099
1022
900
Residual ECH content, ppm
< 5
Hello
Physical properties are comparable
TRFA Annual meeting, Florida, USA

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Typical properties Epoxy resins
Property
TOCN 4030
YDBN 602
TOCN 4030P
YDBN 602P
125oC
2006
1099
7160
3251
Softening point 82 72 92 83
Glass transition temperature 77 67 87 71
Phosphorus content
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
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Curing Behavior of
Epoxy resins
with
Phenolic hardeners
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OCN is fastest reactive phenolic hardener
TRFA Annual meeting, Florida, USA

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YDBN 602 is more reactive because of better structural symmetry and low melt viscosity
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2MI is more reactive compared to TPP because of alkoxide ion formation and more basicity of the 2MI catalyst
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Modified resins are lower in reactivity due to the presence of acidic Phosphorus compounds.
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Possible reaction of Phosphorus Resin with Catalyst
polymerization
Ring cleavage
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Phenolic reactivity trend- OCN>PN>TP>BPN
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Thermal Property
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Sample cured 175oC/6hrs
Concentration of catalyst effect reactivity not the final crosslink structure
2-MI system gives higher Tg than TPP system
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6 hrs at 175oC is adequate curing schedule for full crosslinking
YDBN system shows higher Tg compared to TOCN system
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Sample cured 175oC/6hrs
TP shows highest Tg( oC)
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 oC depending on curing agent
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Flammability
And
Thermal Degradation
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Effect of Phosphorus content on flammability
Phosphorus content
YDBN 602-2MI
TOCN 4030 –2MI
YDBN 602-TPP
TOCN 4030-TPP
V-2
Burn
0.8
V-2 with low burning time
1.2
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
2.0
V-0
V-O
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
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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
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YDBN 602 char yield is higher than TOCN better flammability.
Incorporation of phosphorus increases char yield dramatically.
TPP cured system shows better char yield than 2MI
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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
140oC/15 min, 175oC/6 hrs
Glass fiber content, % 63 62 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
1.97
Flexural modulus, Gpa 27 28 29 34
Water absorption after 8 hrs at 80oC, %
0.1042
0.0941
0.0848
0.0646
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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)
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Conclusion:
Halogen free YDBN-P and TOCN-P resins could be material of choice where high glass transition temperature ( oC) or flammability is desired for electrical and electronics applications.
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.
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.
2MI as catalyst lead to higher Tg of cured matrix compared to TPP.
TRFA Annual meeting, Florida, USA

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Acknowledgement:
Sincerely thanks
Management of TOCC
All Colleagues Somsak, Satid, Thithikan and Thaniya
Mr. Wutti of Mettler Toledo, Thailand
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Thank you
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Any Question?
TRFA Annual meeting, Florida, USA