JP2007146095A - Resin composition, prepreg, and laminated board and printed circuit board produced by using the same - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a resin composition giving a metal-clad laminated board having excellent heat-resistance, peeling strength, etc. <P>SOLUTION: The resin composition contains an inorganic filler and a thermosetting resin as essential components. The inorganic filler comprises aluminum hydroxide having an average particle diameter of 1.0-5.0μm, containing ≤0.2 mass% particles of ≤0.5μm diameter, having a BET specific surface area of ≤1.5 m<SP>2</SP>/g and containing ≤20 ppm of coarse particles having particle diameter of ≥45μm. The invention further provides a prepreg, and a laminated board and a printed circuit board produced by using the composition, etc. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a resin composition from which a metal-clad laminate having improved heat resistance and peel strength, a prepreg, a laminate using the same, and a printed wiring board.

With the downsizing and high performance of electronic devices, printed wiring boards are becoming denser and thinner. In order to cope with the reduction in thickness, there is an increasing demand for high elastic modulus in metal-clad laminates, and the use of fillers is increasing. When a filler is used, high filling with a filler having a high hardness is effective for increasing the elastic modulus of the laminate, but there is a problem that the amount of wear of the drill becomes large during drilling. As a technique for improving drill wear while maintaining high elasticity, there is a method using aluminum hydroxide or the like having a relatively low hardness.
However, since aluminum hydroxide traps a lot of water that exhibits a cooling effect at the time of combustion, there is a problem that the heat resistance of the resin composition or the laminate is drastically lowered when blended in a certain amount or more. This is due to the fact that the temperature at which aluminum hydroxide releases water is lower than the melting temperature of the solder, and it seems that it becomes more prominent in lead-free solders where the melting temperature will become higher in the future. As printed wiring boards are becoming thinner, if the filler contains coarse particles in an ultra-thin laminate, defects may occur in the areas where coarse particles exist, and sufficient insulation reliability can be secured. Disappear.

In general, halogen flame retardants (mainly bromine-based) and phosphorus compounds are used for printed circuit boards and substrates used in semiconductor packages to provide flame retardancy, but extremely toxic dioxins are generated during combustion. Because there is concern, it is in the direction not to use. On the other hand, Sn-Pb solder has been mainly used for mounting components. However, in recent years, the soil has been contaminated at the time of disposal or the like, and the conversion to a solder material that does not use lead has been progressing. With lead-free solder, the melting point rises from 10 ° C. to 40 ° C., so the reflow temperature during mounting also rises to the same extent.
Under these circumstances, packaging substrates that support the environment are required to have excellent heat resistance that is compatible with lead-free solder, as well as having excellent flame resistance without using halogen compounds or phosphorus compounds. ing.

Further, the miniaturization of the pad area of the package is progressing, and it is required that the reliability of the solder ball connection is high in combination with the change in characteristics of the lead-free solder ball. Therefore, an improvement in peel strength (metal foil peeling strength) is strongly desired for the substrate used.
Moreover, in order to improve high temperature characteristics such as strength and elastic modulus in a high temperature range, a higher glass transition temperature (Tg) than before is required. In order to satisfy the demand for the low thermal expansion coefficient and high elastic modulus, there is a method by adding a filler (see, for example, Patent Document 1).
JP 2003-64198 A

  In view of the current situation, an object of the present invention is to provide a resin composition from which a metal-clad laminate with improved heat resistance and peel strength can be obtained.

  As a result of intensive studies to achieve the above object, the present inventor has found that a resin composition comprising an inorganic filler containing a specific aluminum hydroxide and a thermosetting resin meets the above object. I found it. The present invention has been completed based on such findings.

That is, the present invention provides the following resin composition, prepreg, laminate and printed wiring board.
1. An inorganic filler and a thermosetting resin are essential components, and the inorganic filler has an average particle size of 1.0 μm to 5.0 μm, 0.5 μm or less of particles of 0.2% by mass or less, and a BET specific surface area of 1.5 m. ² / g or less, The resin composition characterized by including the aluminum hydroxide whose coarse particle quantity of a particle diameter of 45 micrometers or more is 20 ppm or less.
2. The resin composition according to 1 above, wherein the thermosetting resin is at least one resin selected from the group consisting of epoxy resins, phenol resins, polyimide resins, triazine resins, melamine resins, and modified resins obtained by modifying these resins.
3. The resin composition according to 1 or 2 above, which contains spherical silica having an average particle size of 0.4 to 0.7 μm as an inorganic filler other than aluminum hydroxide.
4). 4. The resin composition as described in 3 above, wherein the inorganic filler in the resin composition is 40 to 70% by mass, 25 to 75% by mass of the inorganic filler is spherical silica, and 25 to 75% by mass is aluminum hydroxide.
5. A prepreg obtained by impregnating a base material with any one of the above resin compositions 1 to 4 and then drying.
6). A laminate obtained by laminating one or more prepregs of 5 above and heating and pressing.
7). 6. The laminate of 6 above, which is a metal-clad laminate obtained by stacking a metal foil on at least one of the stacked prepregs and then heating and pressing.
8). A printed wiring board obtained by processing a circuit using the laminate of 6 or 7 above.

The resin composition of the present invention can be suitably used for printed wiring boards and the like because a metal-clad laminate with improved heat resistance and peel strength can be obtained.
That is, the laminate produced from the resin composition of the present invention uses aluminum hydroxide having a sharp particle size distribution and few fine particles, and thus exhibits high heat resistance. At the same time, good peel strength (metal foil peel strength) can be obtained.

The resin composition of the present invention is characterized in that an inorganic filler and a thermosetting resin are essential components and an inorganic filler containing a specific aluminum hydroxide is used.
First, the aluminum hydroxide used in the present invention will be described in detail.
The aluminum hydroxide used in the present invention has an average particle size of 1.0 μm to 5.0 μm, preferably 2.5 to 4.0 μm. When the average particle size is 1.0 μm or more, when the varnish is made by adding aluminum hydroxide to the resin material, the viscosity is greatly increased, and when impregnating into a glass substrate or pressing a prepreg It is no longer difficult to mold, and the aggregation of particles does not occur and the dispersibility of aluminum hydroxide does not become insufficient. On the other hand, by setting the average particle size to 5.0 μm or less, when the varnish is produced, the sedimentation is quick, so that the workability is not deteriorated, and the insulation reliability corresponding to the recent thinning is high. A substrate can be obtained.

The aluminum hydroxide used in the present invention has a particle size of 0.5 μm or less of 0.2% by mass or less, preferably 0.1% by mass or less, and a BET specific surface area of 1.5 m ² / g or less, preferably 1 .3 m ² / g or less.
Since the dehydration start temperature of aluminum hydroxide is equal to the temperature of transition from the gibbsite type to the boehmite type, the heat resistance of the aluminum hydroxide is improved by suppressing the formation of boehmite. Fine particles of 0.5 μm or less have a large specific surface area and thus have a large amount of moisture adsorbed on the surface, and dehydration starts at a low temperature around 240 ° C. The aluminum hydroxide of the present invention has such fine particles of 0.2% by mass or less. In addition, since it exhibits a sharp particle size distribution, boehmite formation is suppressed, and heat resistance is greatly improved when a resin composition, a laminated board, or a printed wiring board is used.
In addition, since the BET specific surface area is as small as 1.5 m ² / g or less and the particle size of 0.5 μm or less is 0.2 mass% or less and there are few fine particles, the wettability between the resin material and the aluminum hydroxide surface is improved. , Interfacial adhesion is improved. Therefore, an effect of improving the peeling strength of the metal foil in the laminated plate can be obtained.
Further, the aluminum hydroxide used in the present invention has a coarse particle amount of 45 μm or more of 20 ppm or less, preferably 10 ppm or less. By setting it to 20 ppm or less, insulation reliability is ensured and excellent voltage resistance is obtained.
The aluminum hydroxide used in the present invention has a sharp particle size distribution with few fine particles and is excellent in heat resistance, so that resin blistering due to release of water occurs during processing such as soldering. There is no. In particular, it exhibits good heat resistance that can withstand lead-free solder with a high melting temperature.
Furthermore, since the aluminum hydroxide used in the present invention has a very small amount of coarse particles, the insulation reliability and voltage resistance are good even for thin substrates.

In the present invention, it is preferable to use spherical silica having an average particle size of 0.4 to 0.7 μm together with aluminum hydroxide as a filler. By using such spherical silica, improvement in rigidity can be obtained. In addition, by setting the average particle size to 0.4 μm or more, it is possible to avoid the viscosity of the resin composition from increasing and workability to be deteriorated. The occurrence of such problems can be avoided.
In the present invention, in addition to the above aluminum hydroxide and silica, other inorganic fillers can be used in combination. The type, shape, and particle size of the inorganic filler used in combination are not particularly limited. For example, calcium carbonate, alumina, titanium oxide, mica, aluminum carbonate, magnesium silicate, aluminum silicate, short glass fiber, aluminum borate, Examples include various whiskers such as silicon carbide. Several of these may be used.

It is preferable that the compounding quantity of the inorganic filler in a resin composition shall be 40-70 mass%, More preferably, it is 45-60 mass%. When it is 40% by mass or more, the drilling workability is improved, and when it is 70% by mass or less, the fluidity is excellent and the moldability during pressing is improved.
Moreover, it is preferable that spherical silica with an average particle diameter of 0.4-0.7 micrometer is 25-75 mass% in an inorganic filler, and aluminum hydroxide is 25-75 mass%. By making spherical silica and aluminum hydroxide within this range, as described above, it has excellent flame resistance, heat resistance corresponding to lead-free solder, excellent peel strength, drillability, insulation A resin composition is obtained from which a metal-clad laminate having reliability and formability is obtained.

In the present invention, these inorganic fillers include various kinds of coupling agents, silicone polymers, etc. in order to improve the interfacial adhesion between the resin and the filler and the dispersibility of the inorganic filler. It is preferable to perform the surface treatment.
A problem in applying a metal hydroxide such as aluminum hydroxide to the prepreg is that the flame resistance is improved as the filling amount is increased while the heat resistance is lowered. For this reason, conventionally, when the amount necessary for flame retardancy is filled, high heat resistance compatible with lead-free solder could not be obtained.
In the present invention, as a means of improving heat resistance while filling with an inorganic filler and maintaining excellent flame retardancy (UL94 V-0), spherical silica is used together with specific aluminum hydroxide as an inorganic filler, By blending this with a thermosetting resin to form a bulky stress relaxation treatment layer on the surface of the inorganic filler, even if moisture is generated from the inorganic filler, the resin is not directly damaged, Resin cracks due to moisture generation are suppressed in the mounting temperature region of the laminate, and heat resistance is greatly improved.

  Moreover, in this invention, the high dispersibility of a filler is expressed and the viscosity raise of the resin varnish which generate | occur | produces when a filler is highly filled can be suppressed. For this reason, even if the resin is highly filled with a filler, the glass substrate exhibits good impregnation properties, and the substrate made of this material has very good resistance to electric corrosion. In addition, since the interfacial adhesion is greatly improved, it has excellent peel strength, drilling workability and insulation reliability, and is obtained by forming a circuit from a laminate produced using the resin composition of the present invention. The printed wiring board can be compatible with lead-free soldering and has high reliability.

As the coupling agent, for example, a silane coupling agent, a titanate coupling agent, or the like is used. As the silane coupling agent, a carbon-functional silane is used, and 3-glycidoxypropyltrimethoxysilane, 3-glycidoxypropyl (methyl) dimethoxysilane, 2- (2,3-epoxycyclohexyl) ethyltri Epoxy group-containing silane such as methoxysilane; 3-aminopropyltriethoxysilane, N- (2-aminoethyl) -3-aminopropyltrimethoxysilane, N- (2-aminoethyl) -3-aminopropyl (methyl) ) Amino group-containing silane such as dimethoxysilane; Cationic silane such as 3- (trimethoxylyl) propyltetramethylammonium chloride; Vinyl group-containing silane such as vinyltriethoxysilane; 3-Methacryloxypropyltrimethoxysilane Acrylic group-containing silane such as Mercapto group-containing silane such as beauty 3-mercaptopropyltrimethoxysilane and the like.
On the other hand, examples of titanate coupling agents include alkyl titanates such as titanium propoxide and titanium butoxide.
Two or more of these coupling agents and silicone polymers may be used in combination.

The thermosetting resin used in the present invention is not particularly limited. For example, epoxy resins, polyimide resins, triazine resins, phenol resins, melamine resins, and modified resins obtained by modifying these resins are used. Two or more of these resins may be used in combination, and various curing agents, curing accelerators, etc. may be used as necessary, and these may be blended as a solvent solution.
Among these thermosetting resins, it is preferable to use an epoxy resin in consideration of the balance between characteristics such as heat resistance and moisture resistance and cost. As the epoxy resin, a compound having two or more epoxy groups in the molecule is used. For example, bisphenol A type epoxy resin, bisphenol F type epoxy resin, biphenyl type epoxy resin, phenol novolac type epoxy resin, cresol novolak type epoxy resin. Bisphenol A novolac type epoxy resin, bisphenol F novolac type epoxy resin, dicyclopentadiene type epoxy resin, glycidyl ether compound of polyfunctional phenols, glycidyl ether compound of bifunctional alcohols, and hydrogenated products thereof . These epoxy resins may be used alone or in combination of two or more.
Moreover, in order to improve the glass transition temperature (Tg) and heat resistance of the cured resin composition, it is preferable to use an epoxy resin having three or more epoxy groups in the molecule. Examples of such resins include phenol novolac type epoxy resins, cresol novolac type epoxy resins, bisphenol A novolac type epoxy resins, bisphenol F novolak type epoxy resins, and the like.

As the curing agent, various conventionally known ones can be used, and examples thereof include dicyandiamide, diaminodiphenylmethane, diaminodiphenylsulfone, phthalic anhydride, pyromellitic anhydride, polyfunctional phenols such as phenol novolac and cresol novolac. be able to. Several kinds of these curing agents can be used in combination.
As the curing accelerator, for example, an imidazole compound, an organic phosphorus compound, a tertiary amine, a quaternary ammonium salt, or the like is used, and two or more kinds may be used in combination.
Moreover, a coloring agent, antioxidant, a reducing agent, an ultraviolet shielding agent, etc. can be further suitably mix | blended with the resin composition of this invention as needed.

In the present invention, a resin composition containing the above inorganic filler and thermosetting resin is varnished, impregnated into a substrate, heated, dried, and B-staged to obtain a prepreg for a printed wiring board. Can do.
A solvent is used to dilute the resin material and the inorganic filler to form a varnish. The solvent is not particularly limited, and examples thereof include acetone, methyl ethyl ketone, toluene, xylene, methyl isobutyl ketone, ethyl acetate, ethylene glycol monomethyl ether, N, N-dimethylformamide, methanol, ethanol and the like. Several types of these solvents may be mixed. Moreover, the solid content density | concentration of a varnish is not specifically limited, Although it can change suitably with the kind and compounding quantity, etc. of a resin composition and an inorganic filler, the range of 50 mass%-80 mass% is preferable. By setting it to 50% by mass or more, an appropriate varnish viscosity and the resin content of the prepreg are obtained, and by setting it to 80% by mass or less, deterioration of the appearance of the prepreg due to varnish thickening or the like is avoided.

The varnish obtained by blending the above components is impregnated into a base material, and dried in the range of 80 to 200 ° C. in a drying furnace, for example, to obtain a prepreg for a printed wiring board.
The substrate is not particularly limited as long as it is used when producing a metal foil-clad laminate or a multilayer printed wiring board, but a fiber substrate such as a woven fabric or a nonwoven fabric is usually used. Examples of the fiber substrate include inorganic fibers such as glass, alumina, asbestos, boron, silica alumina glass, silica glass, tyrano, silicon carbide, silicon nitride, zirconia, aramid, polyether ether ketone, polyether imide, polyether sal There are organic fibers such as phon, carbon, cellulose and the like, and mixed papers thereof, and glass fiber woven fabric is particularly preferably used.

A laminated board is obtained by stacking at least one prepreg obtained as described above and performing heat and pressure molding. The heating temperature is 150 to 200 ° C., preferably 170 to 190 ° C., and the pressure is 1.0 to 8.0 MPa, preferably 2.0 to 6.0 MPa. The prepreg characteristics, press machine capability, and desired lamination It is determined appropriately depending on the thickness of the plate.
Moreover, a metal-clad laminate can be produced by stacking at least one prepreg, placing a metal foil on one side or both sides, and heat-pressing it. Although copper foil and aluminum foil are mainly used as the metal foil, other metal foils may be used. The thickness of the metal foil is usually 3 to 200 μm.
Furthermore, a printed wiring board is obtained by using these laminates and processing the circuit.

EXAMPLES Next, although an Example demonstrates this invention further in detail, this invention is not limited at all by these Examples.
In the following examples and comparative examples, the part represents part by mass. Moreover, the evaluation methods of heat resistance, peel strength (stripping strength of metal foil), drill workability, insulation reliability (voltage resistance) and formability are as follows.

(1) Heat resistance:
A double-sided copper-clad laminate (4 prepregs) was cut into 50 mm × 50 mm, floated on solder at 260 ° C. and 288 ° C., and the time until blistering was measured.
(2) Peel strength (stripping strength of metal foil):
It measured according to JIS C 5016. The thickness of the copper foil was 18 μm.
(3) Drill workability:
Using double-sided copper-clad laminate (4 prepreg stacks), drill diameter 0.1mm, rotation speed 160krpm, feed rate 1.6m / min, stacking number 2 sheets, entry board 150μm aluminum plate, Hole position accuracy and wall roughness were measured.
(4) Insulation reliability (voltage resistance):
Using a double-sided copper-clad laminate (one prepreg layer), a voltage of 1000 V was applied to the top and bottom of the substrate that was etched on the entire surface for 30 seconds to evaluate the presence or absence of insulation failure. Thirty sheets were measured for each sample, and the number of insulation defects was evaluated.
(5) Formability: visually observed.

Example 1
The following resin materials and inorganic filler were blended, and methyl ethyl ketone was added to prepare a varnish having a solid content of 70% by mass.
(Thermosetting resin)
69 parts of bisphenol A novolac type epoxy resin (trade name Epicron N-865 of Dainippon Ink & Chemicals, Inc.)
Tetrabromobisphenol A type epoxy resin 31 parts (trade name Epicron 153 of Dainippon Ink & Chemicals, Inc.)
Phenol novolac resin 42 parts (trade name Phenolite TD-2106 from Dainippon Ink & Chemicals, Inc.)
(Curing accelerator)
2-ethyl-4-methylimidazole 0.2 part (inorganic filler)
70 parts of aluminum hydroxide (I) (HP-360 manufactured by Showa Denko KK, average particle size 3.2 μm)
70 parts of spherical silica (manufactured by Admatechs SO-25H, average particle size 0.6 μm)
The obtained varnish was impregnated into a glass cloth (# 1080, E-glass) having a thickness of about 0.06 mm and then dried by heating at 150 ° C. for 3 to 10 minutes to obtain a prepreg having a resin content of 60% by mass. Four or one of these prepregs were stacked, a copper foil having a thickness of 18 μm was stacked on both sides thereof, and a double-sided copper-clad laminate was produced under a press condition of 175 ° C., 90 minutes, 3.0 MPa.
The ratio of the varnish solid content, the physical properties of the aluminum hydroxide used, and the evaluation results of the obtained double-sided copper-clad laminate are shown in Table 1.

Example 2
The varnish was prepared using aluminum hydroxide (II) (HP-360 manufactured by Showa Denko KK, average particle size: 4.0 μm) instead of aluminum hydroxide (I) in the same manner as in Example 1. went. The ratio of the varnish solid content, the physical properties of the aluminum hydroxide used, and the evaluation results of the obtained double-sided copper-clad laminate are shown in Table 1.

Comparative Example 1
The varnish was prepared in the same manner as in Example 1 except that the varnish was prepared using aluminum hydroxide (III) (CL-303 manufactured by Sumitomo Chemical Co., Ltd.) instead of the varnish solid content and aluminum hydroxide (I). went. The physical properties of the aluminum hydroxide used and the evaluation results of the obtained double-sided copper-clad laminate are shown in Table 1.

Comparative Example 2
It carried out similarly to Example 1 except having prepared varnish using aluminum hydroxide (IV) (Showa Denko Co., Ltd. product H-32) instead of aluminum hydroxide (I). The ratio of the varnish solid content, the physical properties of the aluminum hydroxide used, and the evaluation results of the obtained double-sided copper-clad laminate are shown in Table 1.

Comparative Example 3
The same procedure as in Example 1 was conducted except that the varnish was prepared using aluminum hydroxide (V) (CL-310 manufactured by Sumitomo Chemical Co., Ltd.) instead of aluminum hydroxide (I). The ratio of the varnish solid content, the physical properties of the aluminum hydroxide used, and the evaluation results of the obtained double-sided copper-clad laminate are shown in Table 1.

Comparative Example 4
It carried out similarly to Example 1 except having prepared varnish using aluminum hydroxide (VI) (Showa Denko Co., Ltd. product H-43) instead of aluminum hydroxide (I). The ratio of the varnish solid content, the physical properties of the aluminum hydroxide used, and the evaluation results of the obtained double-sided copper-clad laminate are shown in Table 1.

Example 3
The same procedure as in Example 1 was performed except that the varnish was prepared with a silica content of 15 parts. The ratio of the varnish solid content, the physical properties of the aluminum hydroxide used, and the evaluation results of the obtained double-sided copper-clad laminate are shown in Table 1.

Example 4
The same procedure as in Example 1 was performed except that the varnish was prepared with 240 parts of silica. The ratio of the varnish solid content, the physical properties of the aluminum hydroxide used, and the evaluation results of the obtained double-sided copper-clad laminate are shown in Table 1.

Claims (8)

An inorganic filler and a thermosetting resin are essential components, and the inorganic filler has an average particle size of 1.0 μm to 5.0 μm, 0.5 μm or less of particles of 0.2% by mass or less, and a BET specific surface area of 1.5 m. ² / g or less, The resin composition characterized by including the aluminum hydroxide whose coarse particle quantity of a particle diameter of 45 micrometers or more is 20 ppm or less.   The resin composition according to claim 1, wherein the thermosetting resin is at least one resin selected from the group consisting of epoxy resins, phenol resins, polyimide resins, triazine resins, melamine resins, and modified resins obtained by modifying these resins.   The resin composition according to claim 1 or 2, which contains spherical silica having an average particle size of 0.4 to 0.7 µm as an inorganic filler other than aluminum hydroxide.   The resin composition according to claim 3, wherein the inorganic filler in the resin composition is 40 to 70 mass%, 25 to 75 mass% of the inorganic filler is spherical silica, and 25 to 75 mass% is aluminum hydroxide. .   A prepreg obtained by impregnating a resin composition according to any one of claims 1 to 4 into a substrate and then drying.   A laminate obtained by stacking one or more prepregs according to claim 5 and heating and pressing.   The laminate according to claim 6, wherein the laminate is a metal-clad laminate obtained by superposing a metal foil on at least one of the overlaid prepregs and then heating and pressing.   A printed wiring board obtained by processing a circuit using the laminated board according to claim 6.