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Description  |
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BACKGROUND OF THE INVENTION
(1) Field of the Invention
The present invention relates to a resin composition for sealing
semiconductors. The composition has a low elastic modulus, a low heat
expansion coefficient, a high resistance to heat and a high resistance to
thermal shock. Accordingly, the composition is particularly suitable for
sealing electronic parts, such as semiconductors, where high reliability
is required.
(2) Description of the Prior Art
Recently, so-called plastic sealing using thermosetting plastics, such as
epoxy resins, has been widely commercialized to seal semiconductors. This
is due to its economical merits, for example, relatively cheap material
cost and ease of mass production. One particular resin composition used
for this purpose comprises a polyfunctional epoxy resin, a phenol novolac
resin and an inorganic filler. The composition is characterized by its
high heat resistance, good processability and excellent electrical
properties.
As the high integration of semiconductor chips has advanced, the size of
the chips have become larger. On the other hand, as the high density
assembly of semiconductors to a substrate has progressed, the shape of
chip-containing packages have become smaller and thinner, such as a flat
package.
The demand for packages in the art has caused some failures which have
heretofore not been observed using conventional sealing resins. The stress
caused by the heat expansion coefficient differences between the sealing
resin and the chip, due to increased chip size and the decrease of resin
layer thickness is believed to have led to cracking of the passivation
film or cracking of the sealing resin composition by thermal shock. This
cracking decreases the humidity resistance of the semiconductor and
results in low reliability of the semiconductor. Therefore, it has been
desired to develop a sealing resin which has decreased stress.
One way to decrease the stress is by reducing the heat expansion
coefficient of the resin to reduce the rate difference between the heat
expansion rate of the resin and that of the chip. However, the rate
difference between the resin and the chip is generally so large that to
lessen the rate difference, it is necessary to incorporate a large amount
of inorganic filler which has a lower heat expansion coefficient. This
type of inorganic filler has already been used for this purpose in sealing
resins, so raising the amount of the filler leads to unacceptable
processability.
Another way to decrease the stress is by reducing the elastic modulus of
the resin. For this purpose, attempts have been made to add a plasticizer
into the resin, to use a pliable epoxy resin or to use a phenolic resin.
However, the cured resins obtained by such attempts have insufficient heat
resistance.
As represented by the Japanese Laid Open Patent (Tokkyo Kokai Koho) No.
58-108220, it was proposed to maintain the heat resistance of the resin by
dispersing rubber particles in the sealing resin to give the resin
crack-resistant properties. However, this method provides certain problems
such as resin deposits on the mold or low heat shock resistance at
temperatures above the glass transition temperature which typically are
encountered in a bath of molten solder. The low heat shock resistance
results in a decrease of the reliability of the semiconductor after
dipping in the bath of molten solder which is a fatal defect for sealing
materials used for integrated circuits.
Additionally, if the degree of deposit on the mold is large, it is
necessary to clean the mold frequently which leads to low productivity and
reduced economy.
SUMMARY OF THE INVENTION
The present invention provides a sealing resin composition for
semiconductors, especially for integrated circuits where high reliability
is required. The resin composition experiences lower stress when used to
seal semiconductors and has a high resistance to thermal shock.
Additionally, the resin composition of the present invention can leave
less deposit on the mold during processing.
After intensive research, it has been found that an effective result is
obtained by dispersing fine particles of silicone rubber which is the
reaction product of a polyaddition reaction of a silicone polymer. Further
investigation has shown the importance of the particle size of the
silicone rubber and thus the present invention has been developed.
In one aspect the present invention provides a semiconductor sealing resin
composition which comprises a modified epoxy resin which is a graft
copolymer of a epoxy resin and a vinyl polymer having dispersed therein a
silicone rubber with an average particle diameter less than 1.0.mu..
DESCRIPTION OF THE PREFERRED EMBODIMENTS
The epoxy resin used in the present invention may be any polyvalent epoxy
resin. It is preferable to use an epoxynovolac resin of glycidyl compounds
such as phenol novolac or cresol novolac for their good electrical
properties and high heat resistance. Another epoxy resin which can be used
is selected from the reaction product of epichlorohydrin o 2-methyl
epichlorohydrin and a compound which has at least two active hydrogen
atoms in the molecule. Exemplary compounds having at least two active
hydrogen atoms in the molecule include: polyvalent phenolic compounds
illustrated by bisphenol A, bishydroxy diphenyl methane, resorcinol,
bishydroxy diphenyl ether and tetrabromo bisphenol A; polyvalent alcohols
illustrated by ethylene glycol, neopentyl glycol, glycerine, trimethylol
propane, pentaerythritol, diethylene glycol, polypropylene glycol,
bisphenol A-ethylene oxide adduct and trishydroxyethylisocyanurate;
polyvalent carboxylic compounds illustrated by adipic acid, phthalic acid
and isophthalic acid; polyamino compounds illustrated by ethylene diamine
and aniline; and epoxy resins of aliphatic compounds (including alicyclic
compounds) illustrated by dicyclopentadiene epoxide or butadiene dimer
epoxide.
The graft polymer used in the present invention can be prepared by carrying
out the polymerization of a vinyl monomer in the presence of the
previously described epoxy resin. The vinyl monomer used to prepare the
vinyl polymer can be selected from alkenyl aromatic compounds, such as
styrene and vinyl toluene; acrylic ester compounds, such as methyl
methacrylate, dodecyl methacrylate, butoxyethyl methacrylate, glycidyl
methacrylate, methyl acrylate, butyl acrylate, 2-ethylhexyl acrylate,
hydroxyethyl acrylate and trimethylolpropane triacrylate; acrylic
compounds which have no ester groups such as acrylonitrile, acrylic acid,
butoxy methyl acrylamide and methacrylamide; nonconjugated vinyl
compounds, such as vinyl acetate, vinyl laurate, vinyl varsatate, vinyl
chloride, vinylidene chloride, ethyl and arylacetate; and conjugated diene
compounds, such as butadiene, isoprene and chloroprene. Other
polymerizable vinyl compounds can also be used such as vinyl silicone,
dibutyl fumarate, mono methyl maleate, diethyl itaconate; and fluorinated
compounds of methacrylic or acrylic acid, such as tetrafluoroethyl
methacrylic acid or tetrafluoro-propyl methacrylic acid.
The amount of the vinyl polymer is usually from about 1 to about 50 parts
by weight to the 100 parts by weight of the epoxy resin.
Preparation of the vinyl polymer is typically conducted by polymerizing the
vinyl monomer in the presence of a free radical initiator. The initiator
can be selected from peroxides, such as lauroyl peroxide, benzoyl
peroxide, tertiary butyl perbenzoate, dimethyl dibenzoyl peroxyhexane,
tertiary butyl perpivalate, ditertiary butyl peroxide, 1,1-bistertiary
butyl peroxy-3,3,5-trimethyl cyclohexane, dimethyl ditertiary butyl
peroxyhexane, tertiary butyl cumyl peroxide, methyl ethyl ketone peroxide,
cumene hydroperoxide, cyclohexanone peroxide cumenehydroperoxide, tertiary
butyl peroxyaryl carbonate, dioctylperoxy dicarbonate, tertiary butyl
peroxy maleic acid, succinic acid peroxide, tertiary butyl peroxy
isopropylcarbonate and hydrogen peroxide. Other initiators which can be
used are azo compounds such as azobisisobutyronitrile or
azobisdimethylvaleronitrile. The amount of the initiator is usually below
10% by weight of the polymerizable vinyl compound.
In some instances, a reducing agent may also be used to carry out a
so-called redox polymerization reaction. Polymerization can also be
conducted in the presence of a polymerization inhibitor, such as
hydroquinone, and/or a chain transfer agent, such as dodecylmercaptan.
The polymerization temperature is usually from about 40 to about
200.degree. C. and the reaction time ranges from about 0.5 to about 24
hours.
To promote the graft polymerization, it is effective to have present a
polymerizable double bond which is in the epoxy resin or a functional
group (such as a peroxide group) which is in the epoxy resin. When a
double bond is used, it is typical to react in advance an epoxy resin and
a compound having both a functional group and a double bond, such as
acrylic acid, acrylamide, methylol acrylamide, butoxy methylacrylamide,
hydroxyethyl methacrylate, glycidyl methacrylate, anhydrous maleic acid,
monoethyl itaconate, monobutyl fumarate, chloromethyl styrene, phosphoxy
ethyl methacrylate, chlorohydroxy propyl methacrylate, parahydroxy styrene
and dimethylamino ethyl methacrylate.
The amount of the compound which has the functional group and polymerizable
double bond is preferably from about 0.1 to about 10 parts per 100 parts
of the epoxy resin by weight.
In the present invention, the graft polymer includes a polymer wherein some
of the epoxy resin or the vinyl polymer remains in the grafted polymer
without being chemically grafted.
The modified epoxy resin of the present invention can be prepared by
conducting an addition reaction according to any known method between an
addition reactive silicone polymer in the presence of the graft polymer of
the epoxy resin and the vinyl polymer. The silicone rubber which can be
used in the present invention is a rubber (either an oligomer or a
polymer) produced by a silation reaction between a vinyl-modified silicone
polymer which has a vinyl group within the molecule and a
hydrogen-modified silicone polymer which has at least two active hydrogen
atoms within the molecule.
The particle diameter of the rubber is below about 1 0.mu., preferably
below about 0.5.mu., more preferably from about, 0.01.mu. to about
0.2.mu.. When the particle diameter is more than about 1.0.mu., it is
difficult to achieve the low degree of the stress which is an object of
the present invention or to achieve an improvement in the resistance to
thermal shock.
The vinyl-modified silicone polymer is a polysiloxane which has at least
one Si--H.dbd.CH.sub.2 group at the end of the molecule or inter-molecule.
The hydrogen-modified silicone polymer which has at least two Si--H groups
at the ends of the molecule or intermolecule. Both of these polymers are
sold commercially and combinations of a vinyl-modified silicone polymer
and a hydrogen-modified silicone polymer are also commercially available.
The ratio of the vinyl-modified silicone polymer to the hydrogen-modified
silicone polymer is usually from about 0.1:10 to about 10:0.1, preferably
from about 1:2 to about 2:1 by weight.
Typical vinyl modified polysiloxanes can have the general formula;
##STR1##
From this formula it will be noted that the silicone polymer has a
Si--CH.dbd.CH.sub.2 group at both ends of the molecule.
The hydrogen-modified polysiloxanes can have the general formula:
##STR2##
From this formula it will be noted that the polymer has a Si--H group at
both ends of the molecule.
Alternatively, the hydrogen-modified polysiloxane can have the general
formula:
##STR3##
In this embodiment, the polymer has Si--H groups in a side chain and can
be adjacent or spaced along the polymer backbone.
A mixture of compounds (II) and (III) wherein the amount of compound (II)
is 0 to 99% by weight is commercially available. Such a mixture is SE-1821
of Toray Silicone Corp. or KE-1204 of Shinetsu Chemicals.
As to the vinyl-modified polysiloxane and hydrogen-modified polysiloxane,
any combination of the polysiloxanes can be used provided that they
produce the silicone rubber by silation reaction. For the polymerization
reaction, it is typical to use a platinum catalyst.
Alternative illustrative vinyl-modified polysiloxanes are:
##STR4##
Similarly, alternative illustrative vinyl-modified polysiloxanes are:
##STR5##
Alternative illustrative hydrogen-modified polysiloxanes are:
##STR6##
The average particle diameter of the silicone rubber obtained by the
addition reaction can be controlled by the amount of the grafted polymer,
its molecular weight or the agitation condition during the reaction. By
increasing the amount of the graft polymer, the particle diameter of the
silicone rubber decreases. Increasing the agitation rate, also decreases
the particle diameter. By increasing the amount of double bonds in the
epoxy resin, e.g., to increase the graft points in number, the particle
diameter tends to decrease. But it is difficult to control the average
particle diameter of the silicone rubber below 1.mu. unless the graft
polymer of the present invention is used.
The present composition can contain an epoxy resin as an additional
component of the composition, if desired. This epoxy resin can be any of
the epoxy resins used in the preparation of the previously described
modified epoxy resin and can be the same or a different epoxy resin used
in the preparation of the modified epoxy resin.
The amount of the epoxy resin as the additional component is below 900
parts to 100 parts of the modified epoxy resin by weight. As to the amount
of the silicone rubber to the total amount of the epoxy resin used in the
composition (i.e., in the modified epoxy resin and the additional
component), it is necessary to use from about 5 to about 50% by weight,
preferably from about 10 to 20% by weight. Below about 5% by weight, the
lower stress on the resin can not be achieved. Above, about 50% by weight,
the deterioration of strength detracts from its commercial use.
The amount of the silicone rubber can be controlled by adjusting the
relative amount of silicon polymer and vinyl monomer used in the
preparation of the modified epoxy resin, but is easier to adjust by
varying the amount of the additional epoxy resin. For this reason, it is
also preferable to use the additional epoxy resin as the additional
component.
A curing agent is also used in the present invention. Typical curing agents
include novolac-type phenolic resins prepared by the reaction between
phenolics, such as phenol or an alkyl phenol, and an aldehyde or
paraformaldehyde. Other modified novolac-type phenolic resins, aralkyl
phenolic resins, amine type curing agent and acid anhydrides can also be
used generally. These compounds can be used alone or in combination.
The amount of curing agent is from about 0.1 to about 10 times the
stoichiometric amount of the epoxy groups of the epoxy resin(s) compared
to the functional groups of the curing agent, preferably from about 0.8 to
about 1.2 times.
An inorganic filler is further used in the present invention. Illustrative
fillers are powders, such as crystallized silica, fused silica, alumina,
talc, calcium silicate, calcium carbonate, mica, clay and titanium
dioxide. Glass fibers or carbon fibers can also be used. These fillers can
be used individually or in combination. From the standpoints of rate of
thermal expansion and rate of conduction of heat, it is preferred to use
silica powder.
The amount of the filler in the composition is from about 200 to about 800
parts to 100 parts of the epoxy resin by weight. Below about 200 parts by
weight, the rate of thermal expansion is too large to obtain a good
resistance to thermal shock. Above about 800 parts by weight, the
flowability of the resin decreases and results in a low processability for
commercial purpose.
It is also possible to add other components to the present semiconductor
sealing resin composition. For example, curing promoters, such as
imidazoles, tertiary amines, phenolics, organic metal compounds and
organic phosphines; mold release agents, for example fatty amides, fatty
acid salts and waxes; fire retardant additives, such as bromo-containing
compounds, antimony and phosphorus; colored fillers, such as carbon black,
and silane coupling agents, can be added to the composition in
conventional amounts.
The present composition can be readily prepared as a molding composition by
premixing the components in a mixer, thereafter kneading at a temperature
of between about 70 and 130.degree. C., for about 0.5 to 90 minutes by a
hot roll or a fusing mixer such as a kneader.
The semiconducter sealing resin composition prepared by the present
invention has the properties of low modulus of elasticity, a low rate of
thermal expansion and good resistance to heat shock. Therefore, a high
degree of reliability can be achieved when the present composition is used
for the sealing of highly-integrated semiconductors or small and thin
semiconductors, such as a flat package.
As a further advantage, the present composition also does not leave
significant deposits on the mold which makes it suitable for long-term
manufacturing.
The present invention is illustrated in detail by the examples which
follow. The present invention should not be construed as being limited to
these examples. In the following examples, a part is a part by weight
unless noted differently.
PREPARATION OF THE MODIFIED EPOXY RESIN
Example 1
A mixture of ortho-cresol novolac epoxy resin (epoxy equivalent 217) 100
parts, toluene 10 parts and methacrylic acid 1.5 parts was reacted at 120
to 125.degree. C. for 2 hours in the presence of tertiary amine. To the
resultant reaction mass were added 7.5 parts of butyl acrylate, 15 parts
of methacryloxy propylsilicone oligomer (from Shinetsu Chemicals), 0.6
part of azobisisovaleronitrile and 200 parts of acetic ether, and reacted
at 75.degree. C. for 4 hours. 10 parts of vinyl-modified polysiloxane and
10 parts of hydrogen-modified polysiloxane (Shinetsu Chemicals KE-1204)
were added to the mass as the silicone polymer and reacted at 75.degree.
C. for two hours while stirring vigorously. The reaction mass was
desolvated at 30.degree. C. under reduced pressure.
A modified epoxy resin (epoxy equivalent 312) in which silicone rubber
having an average particle diameter of 0.1m was dispersed, was thus
obtained.
Example 2
A mixture of ortho-cresol novolac epoxy resin (epoxy equivalent 217) 100
parts, toluene 10 parts and methacrylic acid 1 part was reacted at 120to
125.degree. C. for 2 hours in the presence of tertiary amine. To the
resultant reaction mass were added 5 parts of butyl acrylate, 10 parts of
methacryloxy propylsilicone oligomer (from Shinetsu Chemicals), 0.4 part
of azobisisovaleronitrile and 100 parts of acetic ether, and reacted at
75.degree. C. for 4 hours. 10 parts of vinyl-modified polysiloxane and 10
parts of hydrogen-modified polysiloxane (Shinetsu Chemicals KE-1204) were
added to the mass as the silicone polymer and reacted at 75.degree. C. for
two hours while stirring vigorously. The reaction mass was desolvated at
130.degree. C. under reduced pressure.
A modified epoxy resin (epoxy equivalent 295) in which silicone rubber
having an average particle diameter of 0.35.mu. was dispersed, was thus
obtained.
Example 3
A mixture of ortho-cresol novolac epoxy resin (epoxy equivalent 217) 100
parts, toluene 10 parts and methacrylic acid 0.5 part was reacted at 120
to 125.degree. C. for 2 hours in the presence of tertiary amine. To the
resultant reaction mass were added 2.5 parts of butylacrylate, 5 part of
methacryloxy propyl silicone oligomer (from Shinetsu Chemicals), 0.2 part
of azobisisovaleronitrile and 70 parts of acetic ether, and reacted at
75.degree. C. for 4 hours. 10 parts of vinyl-modified polysiloxane and 10
parts of hydrogen-modified polysiloxane (Shinetsu Chemicals KE-1204) were
added to the mass as the silicone polymer and reacted at 75.degree. C. for
two hours while stirring vigorously. The reaction mass was desolvated at
130.degree. C. under reduced pressure. A modified epoxy resin (epoxy
equivalent 278) in which silicone rubber average particle diameter of
1.0.mu. was dispersed, was obtained.
Example 4
The process of Example 2, was repeated except that 100 parts of phenol
novolac epoxy resin (epoxy equivalent 200) was used instead of
ortho-cresol novolac epoxy resin. The modified epoxy resin (epoxy
equivalent 272), in which silicone rubber having an average particle
diameter of 0.35.mu. was dispersed, was thus obtained.
Example 5
The process of Example 2 was repeated except that 5 parts of 2-ethylhexyl
acrlyrate was used instead of using 5 parts of butyl acrylate. A modified
epoxy resin (epoxy equivalent 295), in which silicone rubber having an
average particle diameter of 0.35.mu. was dispersed, was obtained.
Example 6
The process of Example 2 was repeated except that 10 parts of vinyl
polydimethylsiloxane (Chisso Corp PS 408, having the general formula
described below) was used instead of 10 parts of methacryloxy propyl
silicone oligomer (from Shinetsu Chemicals).
##STR7##
A modified epoxy resin (epoxy equivalent 295), in which silicone rubber
having an average particle diameter of 0.7.mu. was dispersed, was
obtained.
Example 7
The process of Example 2 was repeated except that 15 parts of
vinyl-modified polysiloxane and 15 parts of hydrogen modified polysiloxane
were used instead of using 10 parts of each.
A modified epoxy resin (epoxy equivalent 317), in which silicone rubber
having an average particle diameter of 0.35.mu. was dispersed, was
obtained.
Example 8
A mixture of ortho-cresol epoxy resin (epoxy equivalent 217) 100 parts,
toluene 10 parts and methacrylic acid 1.5 parts was reacted at 120 to
125.degree. C. for 2 hours in the presence of tertiary amine. To the
resultant reactive mass were added 6.5 parts of butyl acrylate, 12 parts
of methacryloxy propyl silicone oligomer (from Shinetsu Chemicals), 0.4
part of azobisisovaleronitrile and 100 parts of acetic ether and reacted
at 75.degree. C. for 4 hours. 70 parts of vinyl-modified polysiloxane and
70 parts of hydrogen-modified polysiloxane (Shinetsu Chemicals KE-1204)
were added to the mass as the silicone polymer and reacted at 75.degree.
C. for two hours while stirring vigorously. The reaction mass was
desolvated at 130.degree. C. under reduced pressure.
A modified epoxy resin (epoxy equivalent 586), in which silicone rubber
having an average particle diameter of 0.4.mu. was dispersed, was thus
obtained.
Example 9
The process of Example 2 was repeated except that 10 parts of
vinyl-modified polysiloxane and 10 parts of hydrogen-modified polysiloxane
(Toray Silicone SE-1821) were used instead of Shinetsu Chemical KE-1204.
A modified epoxy resin (epoxy equivalent 295) in which silicone rubber
having an average particle diameter of 0.35.mu. was dispersed, was
obtained.
Example 10
The process of Example 2 was repeated except that as the silicone polymer,
10 parts of polymer (A) having the structure set forth below was used as
the vinyl-modified polysiloxane and 8 parts of polymer (B) having
structure set forth below and 2 parts of polymer (C) having structure set
forth below were used as the hydrogen-modified polysiloxane.
A modified epoxy resin (epoxy equivalent 295), in which silicone rubber
having an average particle diameter of 0.35.mu. was dispersed, was
obtained.
##STR8##
EXAMPLE 11
Example 2 was repeated except that the 10 parts of the vinyl-modified
polysiloxane and 10 parts of the hydrogen modified polysiloxane were
substituted with 10 parts each of PS 493 and PS 129 which have the
respective structural formulae.
##STR9##
Example 12
Example 2 was repeated except that 4 parts of vinyl modified polysiloxane
and 4 parts of hydrogen modified polysiloxane were used. A modified epoxy
resin (epoxy equivalent 269), in which silicone rubber having an average
particle diameter of 0.35.mu. was dispersed, was obtained.
Comparative Example 1
A mixture of 100 parts ortho cresol novolac epoxy resin (epoxy equivalent
217), toluene 10 parts, methacrylic acid 0.4 parts were reacted in the
presence of a tertiary amine at 120 to 125.degree. C. for two hours. 2
parts of butyl acrylate, 4 parts of methacryroxypropylsilicone oligomer
(Shinetsu Chemicals), 0.4 parts of azobisisovaleronitrile and 50 parts of
acetic ether were added and reacted at 75.degree. C. for four hours.
Thereafter, 10 parts of vinyl modified polysiloxane and 10 parts of
hydrogen modified polysiloxane (Shinetsu Chemicals KE 1204) were added as
the addition reactive silicone polymer and reacted while stirring mildly.
The reaction mass was desolvated at 130.degree. C. under reduced pressure
and thus a modified epoxy resin (epoxy equivalent 273) was obtained in
which silicone rubber which has 1.3.mu. average particle diameter were
dispersed.
Comparative Example 2
A mixture of ortho-cresol novolac epoxy resin (epoxy equivalent 217) 100
parts, toluene 100 parts, silane coupling agent (.alpha.-glycidoxy propyl
trimethoxysilane from Toray Silicone) 16 parts was warmed at 75.degree. C.
and 20 parts of addition reactive silicone polymer (Shinetsu Chemicals
KE-1204) was added and reacted at 75.degree. C. for 2 hours while stirring
vigorously. The reaction mass was desolvated at 130.degree. C. under
reduced pressure.
A modified epoxy resin, in which silicone rubber having a particle diameter
of 1 to 5.mu. was dispersed, was obtained.
Comparative Example 3
100 parts of ortho-cresol novolac epoxy resin (epoxy equivalent 217), 100
parts of toluene, 16 parts of epoxy-modified silicone oil (Toray Silicone)
and 20 parts of dimethylpolysiloxane rubber (Toray Silicone) were mixed at
30.degree. C. for 4 hours.
After desolvation under reduced pressure, a modified epoxy resin, in which
silicone rubber having a particle diameter of 5 to 20.mu. and irregular
shape was dispersed, was obtained.
Preparation and Testing of Sealing Corporations
Sealing compositions containing the modified epoxy resins of the Examples
and Comparative Examples described above were prepared by mixing the
components shown in Table 1 by a mixer, then subjecting the mixture to
melt mixing for 2 to 3 minutes by hot roll at 90.degree. C. The mixture
was thereafter cooled, and ground to obtain the sealing composition.
Test pieces (i.e., 16 pin DIP's equipped with 4.times.8 mm chips) were
prepared using the sealing compositions by transfer molding (at
175.degree. C., 70kg/cm.sup.2, 3 minutes). These test pieces were
subjected to post-cure treatment at 175.degree. C. for 4 hours after
molding before testing. The result of various tests are shown in Table 2.
TABLE 1
COMPARATIVE EXAMPLE EXAMPLE 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 1 2 3 4
Epoxy resin (d) (pbw) 52.6 56.0 56.2 53.8 56.0 56.0 32.7 35.9 21.1
56.0 56.0 56.0 56.6 74.6 56.0 56.0 Preparation No. 1 2 3 4 5 6 2 7 8 8
8 9 10 11 12 Comp. 1 Comp. 2 Comp. 3 Modified epoxy resin (a) Amount
(pbw) 46.8 44.0 41.7 44.0 44.0 44.0 68.0 105 74.3 92.2 111.9 44 44 44
100 41.1 44 44.0 Novolac phenolic (OH equivalent 41.6 41.0 43.1 43.2
41.0 41.0 40.3 35.3 30.8 27.0 21.6 41.0 41.0 41.0 41.0 43.3 46.4 41.0
resin (b) 106)(pbw) Fused silica (c) treated 400 400 400 400 400 400 400
400 400 400 400 400 400 400 400 400 400 400 400 by coupling agent (pbw)
Triphenyl phosphine (pbw) 0.85 0.85 0.85 0.85 0.85 0.85 0.85 0.85 0.85
0.85 0.85 0.85 0.85 0.85 0.85 0.85 0.85 0.85 0.85 Carnuba wax (pbw)
2.52.5 2.5 2.5 2.5 2.5 2.5 2.5 2.5 2.5 2.5 2.5 2.5 2.5 2.5 2.5 2.5 2.5
2.5 Carbon black (pbw) 2.0 2.0 2.0 2.0 2.0 2.0 2.0 2.0 2.0 2.0 2.0 2.0
2.0 2.0 2.0 2.0 2.0 2.0 2.0 Rubber content in the epoxy 6.5 6.5 6.5 6.5
6.5 6.5 10.0 22.0 40 50 53.8 6.5 6.5 6.5 6.5 6.5 resin ( (a) + (d) ) wt
% Average particle diameter (.mu.m) 0.1 0.35 1.0 0.35 0.35 0.7 0.35 0.35
0.4 0.4 0.4 0.35 0.35 0.4 0.35 1.3 1.about. 5 5.about. 20
pbw = parts by weight
TABLE 2
__________________________________________________________________________
Property Tests
Linear
Flexural
Flexural
Expansion
Strength
Modulus
Coefficient .times.
Glass transition
Heat-shock Mold**
(kg/mm.sup.2 A)
(kg/mm.sup.2)
10.sup.-5 /.degree.C.
Temperature
Test*
Deposit
__________________________________________________________________________
Example
1 11.2 1280 1.9 160 0/10 no
2 11.0 1300 1.9 160 0/10 no
3 11.0 1320 1.9 160 1/10 no
4 10.8 1290 1.9 160 0/10 no
5 11.1 1280 1.9 160 0/10 no
6 10.5 1310 1.9 160 1/10 no
7 10.7 1230 1.9 160 0/10 no
8 10.3 1100 1.9 160 0/10 no
9 9.0 920 1.9 160 0/10 no
10 8.0 800 1.9 160 1/10 no
11 7.5 750 1.9 160 2/10 no
12 11.0 1280 1.9 160 0/10 no
13 10.8 1300 1.9 160 0/10 no
14 11.1 1300 1.9 160 0/10 no
15 11.1 1290 1.9 160 0/10 no
Comparative
Example
1 10.8 1330 1.9 160 5/10 no
2 12.5 1650 2.1 160 10/10
no
3 10.5 1350 1.9 158 10/10
no
4 11.0 1320 1.9 157 10/10
yes
__________________________________________________________________________
*The number of cracking after 30 cycles of placing the piece in
280.degree. C., 2 minutes and -196.degree. C., 2 minutes.
**Surface of the mold was checked by eye after molding 20 times by the
same mold.
* * * * *
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