U.S. patent application number 10/310418 was filed with the patent office on 2003-08-21 for thermosetting resin composition for high performance laminates.
This patent application is currently assigned to Isola Laminate Systems Corp.. Invention is credited to Choate, Martin, Peters, Steve, Rafferty, Kevin, Sharma, Jyoti.
Application Number | 20030158337 10/310418 |
Document ID | / |
Family ID | 23320061 |
Filed Date | 2003-08-21 |
United States Patent
Application |
20030158337 |
Kind Code |
A1 |
Choate, Martin ; et
al. |
August 21, 2003 |
Thermosetting resin composition for high performance laminates
Abstract
This invention concerns a thermosetting resin system that is
useful in the manufacture of high performance prepreg, laminate and
composite materials as well as, prepregs, laminates and composites
made from the thermosetting resin composition.
Inventors: |
Choate, Martin; (Onalaska,
WI) ; Sharma, Jyoti; (Landenberg, PA) ;
Peters, Steve; (Rockland, WI) ; Rafferty, Kevin;
(Winona, MN) |
Correspondence
Address: |
Raafat Shaltout
McDonnell Boehnen Hulbert & Berghoff
32nd Floor
300 S. Wacker Drive
Chicago
IL
60606
US
|
Assignee: |
Isola Laminate Systems
Corp.
|
Family ID: |
23320061 |
Appl. No.: |
10/310418 |
Filed: |
December 5, 2002 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
|
60337322 |
Dec 5, 2001 |
|
|
|
Current U.S.
Class: |
525/107 |
Current CPC
Class: |
C08L 9/00 20130101; Y10T
428/2967 20150115; Y10T 428/31529 20150401; C08J 2363/00 20130101;
Y10T 428/31511 20150401; C08L 61/26 20130101; C08L 63/00 20130101;
C08L 79/04 20130101; C08L 25/08 20130101; C08L 63/00 20130101; Y10T
428/2971 20150115; C08L 2666/02 20130101; C08L 2666/02 20130101;
C08L 2666/02 20130101; C08L 2666/04 20130101; C08G 59/4261
20130101; C08J 2479/04 20130101; C08L 35/06 20130101; H05K 1/0353
20130101; Y10T 442/2951 20150401; C08L 2205/00 20130101; C08L 79/04
20130101; C08L 35/06 20130101; Y10T 428/31515 20150401; Y10T
428/31522 20150401; C08J 5/24 20130101; C08L 61/26 20130101 |
Class at
Publication: |
525/107 |
International
Class: |
C08F 008/00 |
Claims
What we claim is:
1. A thermosetting resin composition comprising: (1) at least one
epoxy resin; (2) at least one SMA copolymer; and (3) at least one
bis-maleimidetriazine resin.
2. The thermosetting resin composition of claim 1 including an
accelerator.
3. The thermosetting resin composition of claim 1 including a
filler.
4. The thermosetting resin composition of claim 1 including a
toughener.
5. The thermosetting resin composition of claim 1 including a flame
retardant.
6. The thermosetting resin composition of claim 1 wherein the epoxy
resin comprises an admixture of Bis-A epoxy resin; brominated
bisphenol A diglycidyl ether; and tetrabromobisphenol A.
7. The thermosetting resin composition of claim 2 wherein the
accelerator is an imidazole.
8. The thermosetting resin composition of claim 3 wherein the
filler is selected from teflon, talc, quartz, ceramics, particulate
metal oxides, silica, titanium dioxide, alumina, ceria, clay, boron
nitride, wollastonite, or mixtures thereof.
9. The thermosetting resin composition of claim 4 wherein the
toughener is methacrylate butadiene styrene core shell
particles.
10. The thermosetting resin composition of claim 1 including a
fluorescent dye.
11. A thermosetting resin composition comprising: an epoxy resin
system including an admixture of Bis-A epoxy resin; brominated
bisphenol A diglycidyl ether; and tetrabromobisphenol A; SMA;
Bis-maleimidetriazine resin; methacrylate butadiene core shell
particles; and at least one accelerator.
12. A prepreg comprising a thermosetting resin composition and a
core material, wherein the thermosetting resin composition
comprises: at least one epoxy resin; at least one SMA copolymer;
and at least one bis-maleimidetriazine resin.
13. The prepreg of claim 12 wherein the thermosetting resin
composition includes an accelerator.
14. The prepreg of claim 12 wherein the thermosetting resin
composition includes a filler.
15. The prepreg of claim 12 wherein the thermosetting resin
composition includes a toughener.
16. The prepreg of claim 12 wherein the thermosetting resin
composition includes a flame retardant.
17. The prepreg of claim 12 wherein the epoxy resin comprises an
admixture of Bis-A epoxy resin; brominated bisphenol A diglycidyl
ether; and tetrabromobisphenol A.
18. The prepreg of claim 13 wherein the accelerator is an
imidazole.
19. The prepreg of claim 14 wherein the filler is selected from
teflon, talc, quartz, ceramics, particulate metal oxides, silica,
titanium dioxide, alumina, ceria, clay, boron nitride,
wollastonite, or mixtures thereof.
20. The prepreg of claim 15 wherein the toughener is methacrylate
butadiene styrene core shell particles.
21. The prepreg of claim 12 wherein the thermosetting composition
includes a fluorescent dye.
22. A prepreg comprising a thermosetting resin composition and a
core material, wherein the thermosetting resin composition
comprises: an epoxy resin system including an admixture of Bis-A
epoxy resin, brominated bisphenol A diglycidyl ether, and
tetrabromobisphenol A; SMA; Bis-maleimidetriazine; methacrylate
butadiene core shell particles; and at least one accelerator.
23. A laminate comprising one or more prepregs and one or more
sheets of conducting foil, wherein the one or more prepregs
comprises a thermosetting resin composition and a core material,
and wherein the thermosetting resin composition comprises: at least
one epoxy resin; at least one SMA copolymer; and at least one
bis-maleimidetriazine resin.
24. The laminate of claim 23 wherein the thermosetting resin
composition includes an accelerator.
25. The laminate of claim 23 wherein the thermosetting resin
composition includes a filler.
26. The laminate of claim 23 wherein the thermosetting resin
composition includes a toughener.
27. The laminate of claim 23 wherein the thermosetting resin
composition includes a flame retardant.
28. The laminate of claim 23 wherein the epoxy resin comprises an
admixture of Bis-A epoxy resin; brominated bisphenol A diglycidyl
ether; and tetrabromobisphenol A.
29. The laminate of claim 24 wherein the accelerator is an
imidazole.
30. The laminate of claim 25 wherein the filler is selected from
teflon, talc, quartz, ceramics, particulate metal oxides, silica,
titanium dioxide, alumina, ceria, clay, boron nitride,
wollastonite, or mixtures thereof.
31. The laminate of claim 26 wherein the toughener is methacrylate
butadiene styrene core shell particles.
21. The laminate of claim 23 wherein the thermosetting resin
composition includes a fluorescent dye.
33. A laminate comprising one or more prepregs and one or more
sheets of conducting foil, wherein the one or more prepregs
comprises a thermosetting resin composition and a core material,
and wherein the thermosetting resin composition comprises: an epoxy
resin system including an admixture of Bis-A epoxy resin,
brominated bisphenol A diglycidyl ether, and tetrabromobisphenol A;
SMA; Bis-maleimidetriazine; methacrylate butadiene core shell
particles; and at least one accelerator.
Description
CROSS REFERENCE TO RELATED APPLICATIONS
[0001] This application claims priority from U.S. Provisional
Application Ser. No. 60/337,322, filed Dec. 5, 2001, which is
incorporated herein by reference in its entirety.
BACKGROUND OF THIS INVENTION
[0002] 1. Field of This Invention
[0003] This invention concerns a thermosetting resin system that is
useful in the manufacture of high performance prepreg, laminate and
composite materials as well as the prepregs, laminates and
composites made from the thermosetting resin composition.
[0004] 2. Description of the Related Art
[0005] Plastics have certain mechanical and structural properties
that can be improved when the plastics are combined with
reinforcing components. Composites formed of various fibers
embedded in a polymer resin matrix, for example, are especially
useful. However, such compositions are susceptible to enormous
physical property variations depending upon, for example, the
nature of the fiber used, how the fiber is utilized, and the fiber
matrix or binder. The uses for such composites range from airframes
to tennis rackets and from boat hulls to rocket motor casings, and
laminates for use, for example, as multilayer printed circuit
boards in the electronics industry.
[0006] Performance requirements for composites and laminate
materials are becoming more stringent. In the electronics industry,
for example, high speed high frequency circuits require substrates
with difficult to attain electrical properties, such as low
dielectric loss and low dielectric constant. Current composite
materials do not meet these electrical requirements. In addition,
other materials that may exhibit favorable electrical properties do
not possess the thermal properties required for composites and
laminates. There exists a continuing need, therefore, for new
composite materials having favorable thermal and electrical
properties, such as low dielectric loss and low dielectric
constant.
SUMMARY OF THIS INVENTION
[0007] This invention provides a thermosetting resin composition
useful in the manufacture of high performance composite and
laminate materials. The thermosetting resin composition comprises:
at least one epoxy resin; at least one styrene maleic anhydride
copolymer; and at least one bis-maleimidetriazine resin.
[0008] This invention also provides prepregs, laminates and
composites manufactured from the disclosed thermosetting resin
compositions.
DESCRIPTION OF THE CURRENT EMBODIMENT
[0009] This invention provides thermosetting resin compositions
useful in the manufacture of high performance composite materials,
and prepregs, laminates and composites manufactured therefrom. The
compositions are particularly useful in the preparation of
laminates having low dielectric constants and low dielectric loss
("low loss"). These electrical properties help solve signal speed
and signal integrity problems encountered with high speed analog
digital applications manufactured using laminates with prior art
resin systems.
[0010] Laminate materials manufactured with the thermosetting resin
compositions of the present invention can have low and flat
dielectric loss (.ltoreq.0.01) and low dielectric constant
(.ltoreq.4) at high frequency range of 2 GHz to 10 GHz, at
comparatively low cost. "Flat dielectric loss" means that the
dielectric loss is essentially constant over a range of
frequencies. The compositions of this invention may have a
dielectric loss as low as .ltoreq.about 0.01 over a frequency range
of from 2 to 10 GHz. (As is understood by those skilled in the art,
dielectric loss and constant depend on resin content and can
additionally depend on other factors, such as the substrate used in
a laminate). In addition to having favorable electrical properties,
prepregs prepared from the compositions of this invention are also
non-tacky and easy to process.
[0011] The thermosetting resin composition includes the following
ingredients: (1) at least one epoxy resin; (2) at least one styrene
maleic anhydride; and (3) a bis-maleimidetriazine resin. The
composition optionally includes one or more of the following: (4) a
filler; (5) a toughener; (6) an accelerator; (7) a flame retardant;
(8) a solvent; and/or (9) other additives.
(1) The Epoxy Resin
[0012] The term "epoxy resin" in this context refers to a curable
composition of oxirane ring-containing compounds as described in C.
A. May, Epoxy Resins, 2nd Edition, (New York & Basle: Marcel
Dekker Inc.), 1988.
[0013] The epoxy resin is added to the resin composition in order
to provide the desired basic mechanical and thermal properties of
the cured resin and laminates made there from. Useful epoxy resins
are those that are known to one of skill in the art to be useful in
resin compositions useful for electronic composites and
laminates.
[0014] Examples of epoxy resins include phenol types such as those
based on the diglycidyl ether of bisphenol A ("Bis-A epoxy resin"),
on polyglycidyl ethers of phenol-formaldehyde novolac or
cresol-formaldehyde novolac, on the triglycidyl ether of
tris(p-hydroxyphenol)methane, or on the tetraglycidyl ether of
tetraphenylethane, or types such as those based on
tetraglycidylmethylenedianiline or on the triglycidyl ether of
p-aminoglycol; cycloaliphatic types such as those based on
3,4-epoxycyclohexylmethyl-3,4-epoxycyclohexane carboxylate. The
term "epoxy resin" also includes within its scope reaction products
of compounds containing an excess of epoxy (for instance, of the
aforementioned types) and aromatic dihydroxy compounds. These
compounds may be halogen substituted.
[0015] Preference is given to epoxy resins which are derivatives of
bisphenol A ("Bis-A epoxy resin"), particularly FR4. FR4 is made by
an advancing reaction of an excess of bisphenol A diglydicyl ether
with tetrabromobisphenol A. Mixtures of epoxy resins with
bismaleimide resin, cyanate resin and/or bismaleimide triazine
resin can also be used.
[0016] It should be noted that epoxy resins are generally
represented by a single, unequivocal structural formula. The
skilled person will know that this should be taken to include
deviating products resulting from side reactions occurring during
epoxy resin preparation. As these side products constitute a normal
component of cured epoxy resins, they likewise constitute a normal
component of the resins according to this invention. Epoxy resins
are present in the composition of this invention in an amount from
about 8% to about 26%, and preferably from about 10 to about 23%,
based on 100% by weight solids of the composition.
[0017] Bisphenol A (BPA) and/or bisphenol A diglycidyl ether
(BPADGE) can optionally be included with the epoxy resin as
co-crosslinking agents. Both the BPA and the BPADGE may optionally
be brominated, i.e. substituted with one or more bromine atoms.
Resin systems incorporating optionally brominated bisphenol A and
optionally brominated bisphenol A diglycidyl ether that are useful
in the present invention are described in U.S. application Ser. No.
09/269,014, filed Sep. 24, 1997, which is incorporated herein by
reference in its entirety. In the present invention, the aromatic
moieties of BPA and BPADGE are preferably substituted with two
bromine atoms, to give tetrabromobisphenol A (TBBA) and
tetrabromobisphenol A diglycidyl ether (TBBADGE), respectively.
Optionally brominated novolacs can also be used as co-cross-linking
agent. Brominated co-crosslinking agents are preferred because of
their flame retarding properties.
[0018] The desired resin properties determine the amount of
optionally brominated BPA and optionally brominated BPADGE to be
incorporated into the resin. According to this invention, for
instance, it has surprisingly been found that the Tg of epoxy
resins cross-linked with SMA can be increased substantially by the
use of at least 5% by weight of BPA. Most surprisingly of all, it
is now possible, as indicated above, to obtain resins having glass
transition temperatures of 130.degree. C. and higher even with
simple difunctional epoxy compounds. When a co-crosslinking agent
is used, it is generally present in amount of about 5% to about
60%, preferably about 15% to about 55%, based on 100% by weight
solids of the composition. In a preferred embodiment, the
composition of this invention contains both TBBA and TBBADGE. In
this preferred embodiment, the TBBA is present in an amount of from
about 3% to about 21 wt %, preferably from about 6% to about 19%,
and the TBBADGE is present in amount of from about 9 wt % to about
30 wt %, preferably from about 11 wt % to about 26 wt %, each based
on 100% by weight solids of the composition.
(2) Styrene Maleic Anhydride Copolymer
[0019] The thermosetting resin compositions of this invention
includes one or more styrene maleic anhydride compounds (SMA). SMA
improves the thermal and electrical properties of the resulting
cured polymer and products made therefrom by reacting with
unreacted elastomer ingredients and by-products.
[0020] Copolymers of styrene and maleic anhydride have been
described, inter alia, in Encyclopedia of Polymer Science and
Engineering Vol. 9 (1987), page 225. Within the framework of this
invention the term "copolymer" likewise refers to SMA or mixtures
of SMA. Copolymers of styrene and maleic anhydrides (SMA) are
commercially available in two types. Type 2 comprises mostly
high-molecular weight copolymers (MW generally higher than 100,000,
for instance, 1,000,000). These are in fact thermoplastics, which
are unsuitable for use in the manufacture of prepregs. Moreover,
because of their low anhydride content (5-15%) they are not
particularly suitable for use as a crosslinking agent for epoxy
resin either. The type 1 SMA copolymers, on the other hand, which
have a molecular weight in the range of about 1400 to about 50,000
and an anhydride content of more than 15% by weight, are especially
suited for use in compositions of this invention. Preference is
also given to SMA copolymers having a molecular weight in the range
of 1400 to 10,000. Examples of such copolymers include the
commercially available SMA 1000, SMA 2000, SMA 3000, and SMA 4000.
These copolymers have a styrene maleic anhydride ratio of 1:1, 2:1,
3.1, and 4:1, respectively, and a molecular weight ranging from
about 1400 to about 2000. Mixtures of these SMAs may also be used.
SMA polymers are present in the thermosetting resin compositions of
this invention in an amount from about 10% to about 26%, preferably
from about 15 to about 23%, based on 100% by weight solids of the
composition. In one preferred embodiment, the amount of epoxy resin
exceeds the amount of SMA in order to provide an excess of
functionality of the epoxy over the SMA. In this embodiment, the
weight ratio of epoxy resin to SMA copolymer is preferably about
2:1 to about 1.5:1 (epoxy:SMA).
(3) Bis-maleimidetriazine Resins
[0021] The thermosetting resin compositions of this invention
further includes a Bis-maleimidetriazine resin (BT). BT resins are
commercially available from Mitsubishi. Bis-maleimidetriazine
resins are present in the thermosetting resin compositions of this
invention in an amount from about 15% to about 50%, preferably from
about 25 to about 40%, based on 100% by weight solids of the
composition.
(4) The Optional Filler
[0022] One or more fillers can optionally be added to the resin
compositions of this invention to improve chemical and electrical
properties of the cured resin. Examples of properties that can be
modified with fillers include, but are not limited to, coefficient
of thermal expansion, lowering CTE, increasing modulus, and
reducing prepreg tack. Non-limiting examples of useful fillers
include particulate forms of Teflon.RTM., talc, quartz, ceramics,
particulate metal oxides such as silica, titanium dioxide, alumina,
ceria, clay, boron nitride, wollastonite, and mixtures thereof.
Preferred fillers include calcined clay or fused silica. Another
preferred filler is fused silica. Yet another preferred filler is
silane treated silica. More preferably, the silane treated filler
filler is fused silica treated with epoxy silane. When used,
fillers are present in the thermosetting resin compositions of this
invention in an amount from about 0% to about 20%, preferably from
about 0 to about 10%, based on 100% by weight solids of the
composition.
(5) The Optional Toughener
[0023] The thermosetting resin compositions of this invention may
include one or more tougheners. The tougheners are added to the
resin compositions to improve the drillability of the resulting
composites and laminates. Useful tougheners include methyl
methacrylate/butadiene/styren- e copolymer, methacrylate butadiene
styrene core shell particles, and mixtures thereof. A preferred
toughener is methacrylate butadiene styrene core shell particles,
which is available from Rohm & Haas (100 Independence Mall
West, Philadelphia, Pa.), sold under the trade name Paraloid.RTM..
When used, tougheners are present in the thermosetting resin
compositions of this invention in an amount from about 1% to about
5%, preferably from about 2 to about 4%, based on 100% by weight
solids of the composition.
(6) Accelerators
[0024] One or more accelerators are typically added to the
composition to crosslink the resins and to enhance the rate of
resin cure. The accelerators chosen may be any accelerators that
are know to speed up the rate of thermosetting resin cure. As
suitable accelerators may be mentioned imidazoles, more
particularly alkyl substituted imidazoles such as 2-methylimidazole
and 2-ethyl-4-methylimidazole, 2-phenylimidazole, 2-phenyl,
4-methylimidazole. Other suitable accelerators include tertiary
amines, e.g. benzyldimethylamine and 4,4' and 3,3'
diaminodiphenylsulphone. One preferred accelerator is
2-ethyl-4-methylimidazole. The amount of accelerator used is
dependent on the type of epoxy resin, the type of cross-linking
agent, and the type of accelerator. Employing a too large amount of
accelerator will lead to a too highly reactive resin system. The
skilled person can easily determine the amount of accelerator
needed to provide a resin system that is sufficiently reactive to
allow ready processing into prepregs. In general, such amount will
be between 0.01 and 5% by weight of accelerators, calculated on the
overall weight of epoxy resin and co-crosslinking agent present in
the composition. In many cases this will be the 0.01-0.05% by
weight range. The resin gel is dependent on the type anal amount of
accelerator, the type and amount of solvent, and the type of
prepreg to be manufactured. In the specific case of 2
methylimidazole (2MI) being used as a accelerator, it is preferred
not to use more than about 0.05% by weight of 2MI. By way of
general guideline it can be said that it is advisable not to have a
varnish gel time of less than 120 seconds.
(7) Optional Flame Retardants
[0025] The thermosetting resin compositions of this invention may
include one or more flame retardants. Any flame retardant that is
known to be useful in resin compositions used to manufacture
composites and laminates may be used. Examples of useable flame
retardants include, but are not limited to, halides of glycidyl
etherified bifunctional alcohols, halides of novolac resins such as
bisphenol A, bisphenol F, polyvinylphenol or phenol, creosol,
alkylphenol, catecohl, and novolac resins such as bisphenol F,
inorganic flame retardants such as antimony trioxide, red
phosphorus, zirconium hydroxide, barium metaborate, aluminum
hydroxide, and magnesium hydroxide, and phosphor flame retardants
such as tetraphenyl phosphine, tricresyl-diphenyl phosphate,
triethylphosphate, cresyldiphenylphosphate, xylenyl-diphenyl
phosphate, acid phosphate esters, phosphate compounds containing
nitrogen, and phosphate esters containing halides. Flame retardants
are present in the thermosetting resin compositions of this
invention in an amount of from about 3 to about 9%, preferably from
about 4 to about 8%, based on 100% by weight resin solids of the
composition.
[0026] Another optional flame retardant is decabromodiphenylethane,
which has the following structure: 1
[0027] Decabromodiphenylethane is commercially available, for
example, from Albemarle Corporation (451 Florida St., Baton Rouge,
La. 70801). The Albemarle product is sold as Saytex.TM. 8010.
Decabromodiphenylethane has been unexpectedly found to be easily
dispersed in the resin composition. Decabromodiphenylethane also
has the unexpected and synergistic result of significantly
improving dielectric properties of the cured resin. As a result,
the flame retardant can be included in the resin composition of
this invention in amounts far greater than is necessary for a flame
retardant in order to also enhance the dielectric properties of the
cured resin. When decabromodiphenylethane is used as the flame
retardant, it is preferably present in the thermosetting resin
compositions of this invention in an amount of from about 10% to
about 50%, more preferably from about 20% to about 45%, based on
100% by weight resin solids of the composition. When a brominated
flame retardant is used, it is preferably present in an amount
sufficient to provide a total bromine content to the composition of
about 8% to about 30%, preferably about 10 to about 20%, based on
100% by weight solids of the composition.
(8) Solvents
[0028] One or more solvents are typically incorporated into the
thermosetting resins of this invention in order to provide resin
solubility, control resin viscosity, and in order to maintain the
resin ingredients in a suspended dispersion. Any solvent known by
one of skill in the art to be useful in conjunction with
thermosetting resin systems can be used. Particularly useful
solvents include methylethylketone (MEK), toluene,
dimethylformamide (DMF), or mixtures thereof. The choice of solvent
is often dictated by the resin curing method. When the resin is
cured with hot air, then ketones are typically the preferred
solvent. When the resins are IR cured, then a mixture of ketones
and toluene is typically preferred. When used, solvents are present
in the thermosetting resin compositions of this invention in an
amount of from about 20% to about 50% as a weight percentage of the
total weight of the composition.
[0029] Optionally, the thermosetting resin composition of the
present invention may further contain other additives such as
defoaming agents, leveling agents, dyes, and pigments. For example,
a fluorescent dye can be added to the resin composition in a trace
amount to cause a laminate prepared therefrom to fluoresce when
exposed to UV light in a board shop's optical inspection equipment.
A useful fluorescent dye is a highly conjugated diene dye. One
example of such a dye is UVITEX.RTM. OB
(2,5-thiophenediylbis(5-tert-butyl-1,3-benzoxazole), available from
Ciba Specialty Chemicals, Tarrytown, N.Y.
[0030] One useful composition of this invention has the following
formulation:
1 HIGH PERFORMANCE ELECTRICAL LAMINATE FORMULATION Preferred
Ingredients Range(wt %) Amounts(wt %) Epoxy Resin Bis-A Epoxy Resin
10-26 15-23 Brominated Bis-A Epoxy (TBBADGE) 9-30 13-26
Tetrabromobisphenol A (TBBA) 7-21 11-19 SMA 10-26 15-23 Toughener
1-5 2-4 Methacrylate butadiene styrene core shell particles
(Paraloid 2591) Accelerator 0.05-1.0 0.2-0.5 BT Resin 15-50 25-40
Filler 0-20 0-10
[0031] The ingredients are suspended in a DMF, MEK or MEK/DMF
solvent in a ratio ranging from about 50-80 wt % solids to 50-20 wt
% solvent and preferably about 70 wt % solids to about 30 wt %
solvent.
[0032] The thermosetting resin compositions of this invention are
useful for making prepregs in a continuous process. Prepregs are
generally manufactured using a core material such as a roll of
woven glass web which is unwound into a series of drive rolls. The
web then passes into a coating area where the web is passed through
a tank which contains the thermosetting resin system of this
invention, solvents and other components. The glass web becomes
saturated with the resin in the coating area. The resin saturated
glass web is then passed through a pair of metering rolls which
remove excess resin from the resin saturated glass web and
thereafter, the resin coated web travels the length of a drying
tower for a selected period of time until the solvent is evaporated
from the web. A second and subsequent coating of resin can be
applied to the web by repeating these steps until the preparation
of the prepreg is complete whereupon the prepreg is wound onto
roll.
[0033] Lamination process typically entail a stack-up of one or
more prepreg layers between one or two sheets of conductive foil
(such as copper foil). Lamination methods and parameters may vary
widely, and are generally well known to the person of ordinary
skill in the art. In a typical cure cycle, the stack is maintained
at a pressure of about 40 psi to about 900 psi and under a vacuum
of about 30 in/Hg. The stack temperature is raised from about
180.degree. F. to about 375.degree. F. over a period of about 20
minutes. The stack remains at a temperature of about 375.degree. F.
for 75 minutes after which the stack is cooled from a temperature
of 375.degree. F. to a temperature to 75.degree. F. over a 20
minute period.
[0034] In another process for manufacturing laminates,
thermosetting resins of this invention are premixed in a mixing
vessel under ambient temperature and pressure. The viscosity of the
pre-mix is .about.600-1000 cps and can be adjusted by adding or
removing solvent from the resin. Fabric substrate (typically but
not limited to E glass) is pulled through a dip tank including the
premixed resin, through an oven tower where excess solvent is
driven off and the prepreg is rolled or sheeted to size, layed up
between Cu foil in various constructions depending on glass weave
style, resin content & thickness requirements.
[0035] The thermosetting resin mix can also be coated directly on
Cu substrate (RCC--resin coated Cu) using slot-die or other related
coating techniques.
[0036] The following examples are illustrative of various aspects
of the invention but do not serve to limit its scope.
EXAMPLES
Example 1
Electrical and Thermal Properties
[0037] In this example, the electrical and thermal properties of
castings of the thermosetting resin compositions according to the
invention were measured. The ingredients of the composition and
their amounts are listed in Tables 1 and 2. Table 1 is an unfilled
resin composition. Table 2 is a filled resin composition. DMF was
used as solvent to provide a total solids content of about 67% for
the unfilled resin composition and about 71% for the filled resin
composition.
2TABLE 1 Unfilled Resin Composition Amount Ingredient (percentage
of 100% solids) Epoxy resin Bis A epoxy 17% TBBA 11% TBBADGE 17%
SMA 22.5% BT resin 30% 2-ethyl-4-methylimidazol- e 0.08% Toughener
(Paraloid .RTM.) 2.4% Fluorescent dye (Uvitex .RTM. OB) 0.02%
[0038]
3TABLE 2 Filled Resin Composition Amount Ingredient (percentage of
100% solids) Epoxy resin Bis A epoxy 13% TBBA 8.5% TBBADGE 14% SMA
18% BT resin 24% 2-ethyl-4-methylimidazole 0.07% Toughener
(Paraloid .RTM.) 1.9% Fluorescent dye (Uvitex .RTM. OB) 0.02%
Silica filler 20%
[0039] Physical and electrical properties of the unfilled and
filled resin compositions are provided in Table 3. The data show
that the resin composition exhibit very good Tg values and provides
maximum Dk and Df values of 3.03 and 0.0085, respectively, at high
frequency ranges of about 1 GHz.
4TABLE 3 Physical and electrical properties of filled and unfilled
resin compositions. Dk @ 1 GHz Df @ 1 GHz CTE Tg- CTE 23-288 (after
post (after post RESIN 288 (ppm/.degree. C.) (ppm/.degree. C.)
TgDSC .degree. C. DMA Tg G' bake) bake) Unfilled 193 107 197 175
3.43 0.0085 filled 172 99.6 195 187 3.03 0.0067
[0040] It is contemplated that various modifications may be made to
the compositions, prepregs, laminates and composites of the present
invention without departing from the spirit and scope of the
invention as defined in the following claims.
* * * * *