Low dielectric composite material and laminate and printed circuit board thereof

The present invention belongs to the technical field of resin composite materials, particularly relates to a low dielectric composite material and a laminate and printed circuit board prepared therefrom.

Low dielectric resin materials are currently the main direction for developing a laminate with a high transmission rate, wherein the low dissipation factor (also called dielectric loss tangent) and the low dielectric constant are the main indexes for evaluating the low dielectric resin materials, however, the currently available low dielectric resin materials have the defects of environmentally unfriendly effects caused by using the halogen-containing flame retardants, poor flame retardancy caused by using the general phosphorus-containing flame retardants, poor heat resistances of the laminates, high thermal expansion ratios of the laminates, etc.

In order to overcome the shortcomings of environmentally unfriendly effects caused by using the halogen-containing flame retardants and the defects of poor flame retardancy caused by using the currently available phosphorus-containing flame retardants in the prior art described above, the primary object of the present invention is to provide a low dielectric composite material. The composite material has the properties of high glass transition temperature, low dielectric properties, halogen-free flame retardancy, low thermal expansion ratio of the laminate, etc.

Another object of the present invention is to provide a method for preparing the abovementioned low dielectric composite material.

A further object of the present invention is to provide a laminate and printed circuit board made from the abovementioned low dielectric composite material.

The objects of the present invention can be achieved by the following technical solutions:

a low dielectric composite material is obtained by adhering a low dielectric resin composition with phosphorus-containing flame retardant onto a substrate;

the low dielectric resin composition with phosphorus-containing flame retardant, comprises the following components:

(A) phosphorus-containing flame retardant; (B) vinyl compound;

the phosphorus-containing flame retardant described in the present invention has a structure as shown in formula (I):

wherein, A is a covalent bond, C6˜C12 arylene, C3˜C12 cycloalkylene, C6˜C12 cycloalkenylene, methylene or C2˜C12 alkylene;

R 1 and R 2 are the same or different, and are each a H, alkoxy, aryloxy, alkyl, aryl, or silyl, respectively;

R 3 and R 4 are the same or different, and are each a H, hydroxyl, or C1˜C6 alkyl, respectively, or one and only one of R 3 and R 4 forms a carbonyl with a C;

each of n is independently a positive integer of 1˜6.

However, among them, there are no particular limitations to the abovementioned substrate, any of the materials, which have the supporting and reinforcing effects, can be used. The substrate is preferably one of fiber material, woven, non-woven, PET film (polyester film), PI film (polyimide film), copper foil, and resin coated copper (RCC), such as glass fiber cloth, etc., which can increase the mechanical strength of the composite material. Furthermore, the substrate can be selectively pretreated with a silane coupling agent, without affecting the performances of the low dielectric composite material of the present invention. The composite material has the properties of high glass transition temperature, low dielectric properties, halogen-free flame retardancy, low thermal expansion ratio of the laminate, etc.

The phosphorus-containing flame retardant with the present invention preferably has at least one of the structures as shown in the following formulae (II)˜(XV):

wherein, TMS represents trimethylsilyl.

The phosphorus-containing flame retardant of the present invention has a high melting temperature, more than 300° C.

The vinyl compound can be at least one of vinyl polyphenylene ether resin, vinylbenzyl compound resin, polyolefin compound and maleimide resins.

The vinylbenzyl compound resin is a polymer or prepolymer containing a vinylbenzyl structure, such as DP-85T (vinylbenzyl etherified-dicyclopentadiene-phenol resin) from Chin Yee Chemical Industries Ltd.

The vinyl polyphenylene ether resin refers to a polyphenylene ether resin with the end capping group having an unsaturated double bond (vinyl-terminated polyphenylene ether resin).

Preferably, the vinylpolyphenylene ether resin refers to a polyphenylene ether resin having one of the following structures of the formulae (XVI) and (XVII), but not limited thereto:

wherein, —(O—X—O)— refers to

—(Y—O)— refers to

R 5 and R 6 are each a hydrogen atom, R 7 , R 8 , R 9 , R 10 and R 11 are the same or different, and are each a hydrogen atom, halogen atom, alkyl, or halogen-substituted alkyl respectively;

R 12 , R 13 , R 18 and R 19 are the same or different, and are each a halogen atom, C1˜C6 alkyl or phenyl respectively; R 14 , R 15 , R 16 and R 17 are the same or different, and are each a hydrogen atom, halogen atom, C1˜C6 alkyl or phenyl respectively;

R 20 , R 21 , R 22 , R 23 , R 24 , R 25 , R 26 and R 27 are the same or different, and are each a halogen atom, C1˜C6 alkyl, phenyl or hydrogen atom; A is a C1˜C20 linear, branched, or cyclic alkylene, preferably —CH 2 — or —C(CH 3 ) 2 —;

R 28 and R 29 are the same or different, and are each a halogen atom, C1-C6 alkyl or phenyl; R 30 and R 31 are the same or different, and are each a hydrogen atom, halogen atom, C1˜C6 alkyl or phenyl;

Z represents an organic group having at least one carbon atom, which group can comprise an oxygen atom, nitrogen atom, sulfur atom and/or halogen atom, for example Z can be a methylene (—CH 2 —);

a and b are each a natural number of 1˜30, respectively;

wherein, G is a bisphenol A, bisphenol F or covalent bond; m and n are each a natural number of 1˜15, respectively.

The vinylbenzyl ether polyphenylene ether resin refers to a polyphenylene ether resin having a structure of

More preferably, the vinyl polyphenylene ether resin refers to at least one of methacrylic polyphenylene ether resin (such as the product SA-9000 from Sabic Company), vinylbenzyl ether polyphenylene ether resin (such as the product OPE-2st from Mitsubishi Gas Chemical Company) and modified vinyl polyphenylene ether resin (such as PPE/VBE 7205L from Chin Yee Chemical Industries Ltd.).

The vinyl polyphenylene ether resin of the present invention has lower dielectric properties, i.e., lower dielectric constant and dissipation factor, as compared to the polyphenylene ether resin with a difunctional terminal hydroxyl.

The polyolefin compound can be at least one of styrene-butadiene-divinylbenzene copolymer, hydrogenated styrene-butadiene-divinylbenzene copolymer, styrene-butadiene-maleic anhydride copolymer, polybutadiene-urethane-methyl methacrylate copolymer, styrene-butadiene copolymer, polybutadiene homopolymer, styrene-isoprene-styrene copolymer, maleinized styrene-butadiene copolymer, methylstyrene copolymer, petroleum resin and cyclic olefin copolymer.

There are no particular limitations to the maleimide resin, all of the well-known maleimide resins can be used, the maleimide resin is preferably at least one of the following substances: 4,4′-bismaleimidodiphenyl methane, phenylmethane maleimide oligomer, N,N′-m-phenylene bismaleimide, bisphenol A diphenyl ether bismaleimide, 3,3′-dimethyl-5,5′-diethyl-4,4′-diphenylmethane bismaleimide, N,N′-(4-methyl-1,3-phenylene)bismaleimide, 1,6-bismaleimido-(2,2,4-trimethyl)hexane, 2,3-dimethylphenylmaleimide (N-2,3-xylylmaleimide), 2,6-dimethylphenylmaleimide (N-2,6-xylenemaleimide), N-phenylmaleimide and the prepolymer of the abovementioned compound, such as a prepolymer of a diallyl compound and a maleimide compound.

The low dielectric resin composition with phosphorus-containing flame retardant of the present invention is prepared by mixing the phosphorus-containing flame retardant and the vinyl compound.

The phosphorus content in the low dielectric resin composition with phosphorus-containing flame retardant of the present invention can be adjusted by changing the amount of the phosphorus-containing flame retardant; wherein, the effective flame resistance effect can be achieved, when the phosphorus content in the low dielectric resin composition of the present invention reaches 2 wt %, preferably 2˜3.5 wt %.

The low dielectric resin composition with phosphorus-containing flame retardant of the present invention has high glass transition temperature, low dielectric constant, low dissipation factor, and halogen-free flame retardancy, and the laminate prepared therefrom has good properties of low thermal expansion ratio of the laminate, etc.

In order to achieve the above objects, the low dielectric resin composition with phosphorus-containing flame retardant of the present invention preferably comprises the following components: (A) phosphorus-containing flame retardant; (B) vinyl polyphenylene ether resin; (C) at least one of styrene-butadiene-divinylbenzene copolymer, styrene-butadiene-maleic anhydride copolymer, and polybutadiene-urethane-methyl methacrylate copolymer; and (D) maleimide resin.

More preferably, the following components are comprised, in parts by weight: (A) 10˜90 parts of phosphorus-containing flame retardant; (B) 100 parts of vinyl polyphenylene ether resin; (C) 10˜90 parts of at least one of styrene-butadiene-divinylbenzene copolymer, styrene-butadiene-maleic anhydride copolymer, and polybutadiene-urethane-methyl methacrylate copolymer; and (D) 10˜90 parts of maleimide resin.

Without affecting the effects of the low dielectric resin composition with phosphorus-containing flame retardant of the present invention, at least one of the following additives can further comprise: curing accelerator, solvent, crosslinking agent, silane coupling agent, and inorganic filler.

Without affecting the effects of the low dielectric resin composition with phosphorus-containing flame retardant of the present invention, one or more curing accelerators can be selectively added to promote the curing rate of the resin. Any of the curing accelerators, which can increase the curing rate of the low dielectric resin composition with phosphorus-containing flame retardant of the present invention, can be used. Preferably, the curing accelerator is a curing accelerator comprising a free radical-generating peroxide, including but not limited to: dicumyl peroxide, tert-butyl peroxybenzoate and di(tert-butylperoxyisopropyl)benzene.

More preferably the curing accelerator is di(tert-butylperoxyisopropyl)benzene.

The silane coupling agent can be at least one of the silane compounds and the siloxane compounds.

Preferably, the silane coupling agent is at least one of amino silane compound, amino siloxane compound, styryl silane compound, styryl siloxane compound, acrylic silane compound, acrylic siloxane compound, methylacrylic silane compound, methylacrylic siloxane compound, alkyl silane compound and alkyl siloxane compound.

The solvent can be at least one of methanol, ethanol, ethylene glycol monomethyl ether, acetone, butanone, methylisobutyl ketone, cyclohexanone, toluene, xylene, methoxyethyl acetate, ethoxyethyl acetate, propoxyethyl acetate, ethyl acetate, dimethyl formamide, propylene glycol methyl ether, γ-butyrolactone (GBL) and diisobutyl ketone (DIBK).

The main role of the addition of the inorganic filler is to increase the thermal conductivity of the resin composition, improve the properties of thermal expansivity, mechanical strength, etc., and preferably, the inorganic filler is uniformly distributed in the resin composition.

Preferably, the inorganic filler can comprise at least one of silicon dioxide (spherical, fused, non-fused, porous, or hollow type), aluminum oxide, aluminum hydroxide, magnesium oxide, magnesium hydroxide, calcium carbonate, aluminum nitride, boron nitride, aluminum silicon carbide, silicon carbide, sodium carbonate, titanium dioxide, zinc oxide, zirconium oxide, quartz, diamond powder, diamond-like powder, graphite, magnesium carbonate, potassium titanate, ceramic fiber, mica, boehmite, zinc molybdate, ammonium molybdate, zinc borate, calcium phosphate, calcined talc, talc, silicon nitride, mullite, calcined kaolin clay, clay, basic magnesium sulfate whisker, mullite whisker, barium sulfate, magnesium hydroxide whisker, magnesium oxide whisker, calcium oxide whisker, carbon nanotube, nano-size silicon dioxide and inorganic powder related therewith, and powder particle with the outer shell of the organic core modified with an insulator. And the inorganic filler can be in a spherical, fibrous, plate, granular, flake or needle whisker form.

The method for preparing the low dielectric composite material of the present invention, particularly comprises the following steps:

the low dielectric resin composition with phosphorus-containing flame retardant is dissolved in a solvent, and made into a resin varnish, then adhered onto the substrate in an impregnation or coating means, and formed into a semi-cured state through heating at a high temperature, thus obtaining a low dielectric composite material.

The abovementioned composite material can be cured and formed a cured sheet or cured insulating layer through heating at a high temperature or heating at a high temperature and under a high pressure, wherein if the resin composition contains a solvent, the solvent will be removed via volatilization during heating at a high temperature.

In the above preparation method, the solvent can be at least one of methanol, ethanol, ethylene glycol monomethyl ether, acetone, butanone, methylisobutyl ketone, cyclohexanone, toluene, xylene, methoxyethyl acetate, ethoxyethyl acetate, propoxyethyl acetate, ethyl acetate, dimethyl formamide, propylene glycol methyl ether, γ-butyrolactone and diisobutyl ketone.

In the above preparation method, depending on the requirements of the production process, the solid content of the resin varnish can be freely adjusted, preferably, 45˜70 wt %. The heating at a high temperature refers to heating to volatilize the solvent at a temperature, which can be freely adjusted depending on the solvent species, preferably 100˜170° C. There are no specific limitations to the thickness of the low dielectric composite material of the present invention, which can be adjusted depending on the practical requirements, preferably 30˜75 μm, more preferably 38˜50 μm.

Depending on the different substrates used, the different products, such as prepreg, resin film, resin coated copper, flexible resin coated copper, etc., can be obtained from the low dielectric composite material of the present invention.

The resin varnish of the low dielectric resin composition with phosphorus-containing flame retardant is impregnated onto the fiber material, woven or non-woven, and formed into a semi-cured state through heating at a high temperature, thus obtaining a prepreg.

Alternatively, the resin varnish of the low dielectric resin composition with phosphorus-containing flame retardant is coated onto the PET film or PI film, and formed into a semi-cured state through heating at a high temperature, thus obtaining a resin film.

Alternatively, the resin varnish of the low dielectric resin composition with phosphorus-containing flame retardant is coated onto the copper foil or the PI film of the PI film coated copper, and formed into a semi-cured state through heating at a high temperature, thus obtaining a resin coated copper; the abovementioned resin coated copper obtained by coating onto the PI film of the PI film coated copper also called as flexible resin coated copper.

Namely, the resin varnish of the low dielectric resin composition with phosphorus-containing flame retardant is coated onto the PI film of the PI film coated copper, and obtained a flexible resin coated copper through heating at a high temperature.

A laminate is obtained from the abovementioned low dielectric composite material. The laminate is obtained by superimposing and laminating the low dielectric composite material of the present invention described above and a metal foil. The metal foil may be any of the common metals in the art, such as copper foil. The prepared copper clad laminate has the properties of high glass transition temperature, low dielectric properties, halogen-free flame retardancy, low thermal expansion ratio of the laminate, etc., and is particularly suitable for a high speed and high frequency signal transmission printed circuit board. The laminate comprises two or more layers of metal foil and at least one layer of the composite material interposed therebetween. Among them, the metal foil, such as copper foil, can further comprise a metal alloy of at least one of aluminum, nickel, platinum, silver, gold, etc.; the laminate is formed by superimposing the abovementioned composite material between the two layers of the metal foil and laminating at a high temperature and under a high pressure.

The laminating process conditions can be the common laminating process conditions in the art.

A printed circuit board is obtained from on the abovementioned laminate.

The laminate of the present invention described above is carried out a further manufacturing process, such as manufacturing circuit, etc., then a printed circuit board can be obtained. The printed circuit board is engaged with the electric components, then operated in a harsh environment, such as at a high temperature, under a high humidity, etc., without affecting its quality. The printed circuit board prepared from the abovementioned present invention has the properties of high glass transition temperature, low dielectric properties, halogen-free flame retardancy, low thermal expansion ratio of the laminate, etc., and is suitable for high speed and high frequency signal transmission. Among them, the printed circuit board comprises at least one of the abovementioned laminates, and the circuit board can be made from the well-known processes in the art.

The mechanism of the present invention is:

In the present invention, the diphenylphosphine oxide is derivatized, and prepared a phosphorus-containing flame retardant, which has no reactive functional groups, and has better dielectric properties, as compared to the general phosphorus-containing resin, which has excessively high dielectric properties due to having polar groups, for example the phosphorus-containing phenolic resin currently widely used in the art, such as DOPO-bisphenol A phenolic novolac resin (DOPO-BPAN) (XZ92741 from DOW chemical), having a hydroxyl group, which is a polar functional group and can cause the excessively high dielectric properties; and the melting point of the phosphorus-containing flame retardant of the present invention is high (more than 300° C.), which is much higher than those of the low melting point nonreactive phosphorus-containing flame retardants currently widely used in the art, such as phosphazene compound (SPB-100 from Otsuka Chemical Co., Ltd., with a melting point of about 110° C.) and phosphate compounds (PX-200 from Daihachi Chemical Industry Co., Ltd., with a melting point of about 105° C.), and when the phosphorus-containing flame retardant of the present invention is used in combination with the vinyl compound, composite material, laminate and printed circuit board having low thermal expansion ratio, high heat resistance, high glass transition temperature and low dielectric constant and dissipation factor, can be prepared.

As compared to the prior art, the present invention has the following advantages and beneficial effects:

(1) the phosphorus-containing flame retardant in the low dielectric resin composition components with phosphorus-containing flame retardant of the present invention, does not contain the reactive functional groups, and does not react in the reaction, thus having better dielectric properties.

(2) the phosphorus-containing flame retardant of the present invention has a high melting point (more than 300° C.), when it is used in combination with the vinyl compound, a prepreg, resin film, laminate and circuit board having low thermal expansion ratio, high heat resistance, high glass transition temperature, and low dielectric constant and dissipation factor, can be prepared.

(3) the low dielectric resin composition with phosphorus-containing flame retardant of the present invention, can effectively achieve the flame resistance effect of UL94 V-0, without using the halogen-containing flame retardant.

FIG. 1 is a TGA Thermo Gravimetric Analysis diagram of the phosphorus-containing flame retardant prepared in the example 1.

FIG. 2 is a DSC melting point diagram of the phosphorus-containing flame retardant prepared in example 1.

FIG. 3 is a FTIR spectrogram of DPPO.

FIG. 4 is a FTIR spectrogram of the phosphorus-containing flame retardant prepared in example 1.

Hereinafter the present invention is further described in detail in combination with the examples and the accompanying drawings, but the embodiments of the present invention are not limited thereto.

The chemical names used in the following examples are as follows:

DPPO: diphenylphosphine oxide, purchased from Eumate International Corp.

SA-9000: methyl acrylate-terminated bisphenol A polyphenylene ether resin, purchased from Sabic Company.

OPE-2st: vinylbenzyl ether-terminated diphenyl polyphenylene ether resin, purchased from Mitsubishi Gas Chemical Company.

Ricon184Ma6: styrene-butadiene-maleic anhydride copolymer, purchased from Cray Valley Company.

Ricon257: styrene-butadiene-divinylbenzene copolymer, purchased from Cray Valley Company.

Homide108: phenylmethane maleimide, purchased from Hos-Technik Company.

SPB-100: phosphazene compound, purchased from Otsuka Chemical Co., Ltd.

PX-200: resorcinol bis[di(2,6-dimethylphenyl)phosphate], purchased from Daihachi Chemical Industry Co., Ltd.

XZ92741: DOPO-bisphenol A phenolic novolac resin, purchased from Dow chemical.

DCP: dicumyl peroxide, purchased from Eumate International Corp.

R-45vt: polybutadiene-urethane-methyl methacrylate, purchased from Cray Valley Company.

SQ-5500: spherical silicon dioxide treated with alkyl siloxane compound, purchased from Admatechs Company.

DP-85T: vinylbenzyl etherified-dicyclopentadiene-phenol resin, purchased from Chin Yee Chemical Industries Ltd.

PPE/VBE 7205L: modified vinyl polyphenylene ether resin, purchased from Chin Yee Chemical Industries Ltd.