JP2003027035A - Adhesive composition and adherent sheet - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain an adhesive composition, which can exhibit reduced permittivity and dielectric dissipation factor in a bonding layer, can hence show improved dielectric properties in the whole including an adherend, and preferably has a good heat resistance and bond strength, and to prepare an adherent sheet prepared by molding the same into a sheet. SOLUTION: There is provided an adhesive composition formed by dispersing a filler in a base material containing an adhesive component, wherein the filler is a porous resin particle, and the relative permittivity at 10 GHz of a resin constituting the porous resin particle is lower than the relative permittivity of the solid component in the base material.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an adhesive composition in which a filler is dispersed in a base material containing an adhesive component and an adhesive sheet obtained by molding the same into a sheet, which has a low dielectric constant. It is particularly useful as a compounded adhesive composition for producing a multilayer wiring board for high frequency applications.

[0002]

2. Description of the Related Art With the recent increase in information processing speed in information / communication equipment and the increase in frequency of communication radio waves, a wiring board on which electronic parts and the like are mounted is required to have a high frequency capability. For example, in order to develop excellent high-frequency transmission characteristics and low crosstalk characteristics in the insulating layer of the wiring board,
It is required that the dielectric constant and dielectric loss tangent at high frequencies are small.

That is, in the circuit of the wiring board, energy loss called transmission loss occurs in the transmission process, and this loss is proportional to the product of the signal frequency f, the relative permittivity ε, and the dielectric loss tangent tan δ of the material. Therefore, a high-frequency wiring board having a large frequency f requires a material having a small relative permittivity ε and a low dielectric loss tangent tan δ. Further, since the signal transmission speed is inversely proportional to the 1/2 power of the relative permittivity ε, from this point as well, a high relative permittivity ε is desired for high frequency applications.

As a method of forming such an insulating layer having a low dielectric constant and a low dielectric loss tangent, it has been general to use a resin material having a low dielectric constant. As such a low dielectric constant resin material, for example, a fluorine-containing polymer such as polytetrafluoroethylene or a polyimide resin is known. In many cases, such an insulating layer is laminated and adhered via an adhesive sheet or an adhesive composition after a wiring pattern on the surface is formed to manufacture a multilayer wiring board.

[0005]

However, even if only the insulating layer has a low dielectric constant and a low dielectric loss tangent, unless the adhesive sheet has a low dielectric constant, the effect of improving the dielectric properties of the multilayer wiring board as a whole is improved. Becomes smaller. In particular, in the case of a laminated structure in which an adhesive sheet or the like is embedded between wiring patterns in the same wiring layer, the dielectric constant of the adhesive sheet greatly affects the crosstalk characteristics.

On the other hand, an adhesive sheet or the like used for manufacturing a multilayer wiring board is required to have heat resistance capable of withstanding solder reflow and adhesive strength with an insulating layer and a metal layer.
However, the above-mentioned problems such as improvement in dielectric properties, heat resistance and adhesion strength are not limited to adhesives for manufacturing multilayer wiring boards, and are versatile problems widely required for adhesives. .

Therefore, an object of the present invention is to reduce the dielectric constant and dielectric loss tangent of the adhesive layer, and thus to improve the dielectric properties of the entire adherend, and preferably, an adhesive having good heat resistance and adhesive strength. It is intended to provide a composition and an adhesive sheet obtained by forming the composition into a sheet.

[0008]

[Means for Solving the Problems] The inventors of the present invention have made extensive studies to achieve the above object. As a result, by using porous resin particles as a filler for the adhesive, voids derived from the porous resin particles are formed in the adhesive layer. The present invention has been completed by discovering that the adhesive layer can be formed to have a low dielectric constant and the like.

That is, the adhesive composition of the present invention is an adhesive composition in which a filler is dispersed in a base material containing an adhesive component, wherein the filler is porous resin particles, and It is characterized in that the resin constituting the resin particles has a relative dielectric constant at 10 GHz of not more than the relative dielectric constant of the solid material of the base material.
In the present invention, the physical properties such as the relative dielectric constant are specifically measured by the methods described in Examples.

In the above, it is preferable that the porous resin particles are contained in an amount of 10 to 300 parts by weight based on 100 parts by weight of the solid content of the base material, and the average primary particle diameter is 0.05 to 20 μm.

It is preferable that the resin constituting the porous resin particles is an aromatic polyimide and the adhesive component contains a thermosetting component. Further, the adhesive component,
It preferably contains a polyimide precursor.

On the other hand, the adhesive sheet of the present invention is obtained by molding the adhesive composition according to any one of the above into a sheet.

This adhesive sheet is preferably used for manufacturing a multilayer wiring board.

[Operation and Effect] According to the adhesive composition of the present invention, since the filler dispersed in the base material is porous resin particles, as shown by the results of the examples, the adhesive layer after curing or solidification is Since it has voids, the dielectric constant and dielectric loss tangent of the adhesive layer can be reduced. At that time, since the relative permittivity of the resin constituting the porous resin particles at 10 GHz is equal to or lower than the relative permittivity of the solid material of the base material, the improvement effect of the voids is not offset, and the improvement effect of the dielectric property of the adhesive layer is Can be increased. Further, this can improve the overall dielectric characteristics including the adherend.

The porous resin particles have a base material solid content of 100.
When it is contained in an amount of 10 to 300 parts by weight with respect to parts by weight and the average primary particle diameter is 0.05 to 20 μm, voids can be efficiently formed in the adhesive layer after curing or solidification while maintaining the adhesive strength to some extent. Therefore, the dielectric constant and dielectric loss tangent of the adhesive layer can be reduced more reliably.

When the resin constituting the porous resin particles is an aromatic polyimide and the adhesive component contains a thermosetting component, the porous resin particles have heat resistance and the base material also has heat resistance. Thus, the thermosetting adhesive composition is particularly preferable for applications where heat resistance is required.

When the adhesive component contains a polyimide precursor, particularly high adhesive strength can be obtained when the adherend is a polyimide resin or the like, and when the porous resin particles are a polyimide resin. In addition, the adhesiveness with the base material can be improved.

On the other hand, when the adhesive sheet of the present invention is formed by molding the adhesive composition according to any one of the above into a sheet shape, since the bonding can be performed in a dry process, a wiring layer or the like can be adhered. The bonding process with the body can be performed by a simple process.

Since this adhesive sheet can reduce the dielectric constant and dielectric loss tangent of the adhesive layer and preferably has good heat resistance and adhesive strength, it is suitable for manufacturing a multilayer wiring board, particularly a multilayer wiring board for high frequency applications. Can be used.

[0020]

BEST MODE FOR CARRYING OUT THE INVENTION Embodiments of the present invention will be described below. The adhesive composition of the present invention comprises a base material containing an adhesive component and a filler dispersed therein. The present invention is characterized in that the filler is porous resin particles, and the relative dielectric constant at 10 GHz of the resin forming the porous resin particles is not more than the relative dielectric constant of the solid material of the base material. In particular, the resin that constitutes the porous resin particles has a relative dielectric constant (10 GHz) of 2.5 when the effect of improving the dielectric properties is large.
It is preferably ˜3.5.

The material of the resin constituting the porous resin particles may be any as long as it satisfies the above-mentioned relative permittivity, and various polymers from general-purpose polymers to engineering plastics are used. You can In the present invention, those having heat resistance are preferable, and examples thereof include heat resistant resins such as polyimide, polyamide, polyamideimide, polyether ether ketone, polyphenylene sulfide, polybenzimidazole, PTFE and PFA. Among them, aromatic polyimide or aromatic polyamide is preferable.

The method for producing the porous resin particles includes a method of precipitating a polymer dissolved in a solvent or melted by itself in the form of porous particles or as an aggregate of fine particles, and the same precipitation and formation during polymerization of a monomer. To obtain porous resin particles,
A method of obtaining porous resin particles by replacing a solvent or the like from a resin composition dispersed in the form of droplets, a method of agglomerating and granulating resin fine particles (including pulverized products, fibrils, etc.) to obtain porous resin particles, etc. Either may be used.

Therefore, the shape of the porous resin particles may be any of spherical crystals, aggregates thereof, fine particle aggregates, particles having fine porosity and aggregates thereof, fibril aggregate columnar crystals, fibril aggregates, and the like. In the present invention, in particular, a spherical crystal having a leaf structure in which the particle surface has an aggregate of multiple leaf pieces, particularly an agglomerate thereof, is more preferable, whereby the surface porosity becomes extremely large, and the effect of improving the dielectric properties becomes larger.
Such spherical crystals and aggregates thereof can be obtained, for example, as follows.

In the case of an aromatic polyimide, a polyimide solution is obtained by heating and polymerizing an aromatic tetracarboxylic dianhydride and an aromatic diamine in an organic solvent, and then the temperature of the solution is lowered to obtain polyimide particles. Should be deposited. Further, in the case of an aromatic polyamide, a polyamide solution is obtained by heating and polymerizing an aromatic dicarboxylic acid or its derivative and an aromatic diamine in an organic solvent, and then the temperature of the solution is lowered to precipitate polyamide particles. You can do it.

However, as the monomer component of the aromatic polyimide or the aromatic polyamide, the polyimide or the like produced from the polymerization reaction thereof becomes a uniform polymerization solution near the boiling point of the organic solvent, and the polyimide is precipitated at a lower temperature than that. What comes is preferred. For example, by using 4,4′-diaminodiphenyl ether having an ether bond as an aromatic diamine to impart appropriate flexibility to the obtained polyimide or the like, it is possible to appropriately dissolve the polyimide in a polymerization solvent at the end of the polymerization. It is preferable to impart the property. Further, such a component may be used as the aromatic acid component, and those having an aromatic ring bonded by a carbonyl bond, a sulfonyl bond, a methine bond or the like in addition to an ether bond can be appropriately used. Among them, the combination of 3,3 ′, 4,4′-biphenyltetracarboxylic dianhydride and 4,4′-diaminodiphenyl ether is most preferable.

The average primary particle diameter of the porous resin particles in the present invention is preferably 0.05 to 20 μm, and 0.1 to 10
μm is more preferable. Here, the average primary particle diameter is a value obtained by measuring 20 or more arbitrary particles with a scanning electron microscope. If it is smaller than this range, it becomes difficult to form a porous structure having a high porosity, and it tends to be difficult to efficiently form voids in the adhesive layer. On the other hand, if it is larger than this range, the porous structure also becomes large, and the voids formed by the base material entering during dispersion are relatively small, and the effect of improving the dielectric properties tends to be small. The adhesive strength tends to decrease.

The bulk density (apparent density) of the porous resin particles is 0.1 in order to efficiently form voids in the adhesive layer.
~ 1.0 g / cm ³ is preferred, 0.3-0.7 g / c
m ³ is more preferable. Here, the bulk density is JIS K68.
It is a value measured by 91.

The content of the porous resin particles is such that the base material solid content is 1
10 to 300 parts by weight is preferable with respect to 00 parts by weight, and 5
0 to 200 parts by weight is more preferable. If the amount is less than this range, the voids formed are reduced and the effect of improving the dielectric properties tends to be reduced. On the other hand, if it is larger than this range, the adhesive strength tends to decrease.

The adhesive composition of the present invention may be of a solvent type, and in that case, the base material containing the adhesive component may contain a solvent. However, it is preferable that the solvent does not dissolve the porous resin particles. The adhesive component may be any component as long as it has adhesiveness, such as thermosetting resin, thermoplastic resin, both of them, natural polymer,
Examples include rubber-based components. Among them, it is preferable that the adhesive component contains a thermosetting resin or a thermosetting component such as a monomer or oligomer thereof. The adhesive component may include a curing agent, a cross-linking agent, a tackifier, and the like.

When the adhesive layer is required to have heat resistance such as when it is used for manufacturing a wiring board, the thermosetting resin includes epoxy resin, polyimide resin, polyphenylene ether resin, BT resin, MS resin and the like. To be In particular, as a material having a great effect of improving the dielectric property, a material having a relative dielectric constant (10 GHz) of the base material solid content of 3 to 5 is preferable. As such a low dielectric constant thermosetting resin, a modified epoxy resin type, a polyimide resin type, a polyphenylene ether resin type, and a BT resin type thermosetting resin are known.

In the present invention, it is particularly preferable that the adhesive component contains an imide group-containing (meth) acrylate or a copolymer thereof, or a polyimide precursor for the above-mentioned reason. Specifically, (1) imide group-containing (meth) acrylate (A), alkyl (meth) acrylate (B)
And an acrylic polymer obtained by copolymerizing a monomer mixture containing a functional group-containing monomer (C) having reactivity with an epoxy group, and an acrylic thermosetting adhesive component containing an epoxy resin, (2 ) Acrylic system containing an acrylic polymer obtained by copolymerizing a monomer mixture containing an imide group-containing (meth) acrylate (A), an alkyl (meth) acrylate (B) and an epoxy group-containing monomer (C) A thermosetting adhesive component, (3) a thermosetting component and a thermoplastic component are contained, the thermosetting component contains an epoxy resin and a curing agent therefor, and the thermoplastic component contains an imide group ( Meta)
A thermosetting adhesive component containing an acrylic resin containing the acrylate (a) as a monomer unit,
(4) A thermal imidization type adhesive component containing a polyamic acid (polyamic acid) as a main component, and the like.

In the method of preparing the adhesive composition of the present invention, it is preferable that the porous resin particles are mixed and dispersed in the base material having a certain degree of viscosity in order to efficiently form the voids in the adhesive layer. Specifically, the viscosity measured by an E-type viscometer is 0.5 to 5
It is preferable to mix with the base material of 0 Pa · s. The viscosity can be adjusted by the amount of the solvent component and the molecular weight of the adhesive component.

In the adhesive composition of the present invention, in addition to the above-mentioned adhesive components, solvent and porous resin particles, other fillers and adhesiveness improving agents are used as long as the effect of improving the dielectric properties of the adhesive layer is not impaired. An agent, a curing accelerator, a catalyst and the like may be contained.

The adhesive composition of the present invention may be applied as it is, used as an adhesive sheet, or may be used as a prepreg by impregnating it with a reinforcing material such as a polymeric nonwoven fabric or a woven fabric of glass fibers. Also, separators, metal foil,
An adherend such as a film may be laminated and used. The conditions for curing and solidifying the adhesive composition are appropriately set according to the adhesive component contained.

On the other hand, the adhesive sheet of the present invention is obtained by molding the above adhesive composition into a sheet. The sheet-like material can be formed by applying an adhesive composition containing a solvent to a substrate and then drying the solvent, extruding the softened adhesive composition into a sheet using a T-die, semi-curing or the like. Any method such as a method including a step such as stretching may be used.

The thickness of the adhesive sheet is preferably 5 to 50 μm in order to reduce the thickness of the wiring board and the like while maintaining the adhesive strength. The porosity of the adhesive sheet is preferably 20 to 70% after curing or solidification, and 30 to 50.
% Is more preferable. An adhesive sheet that does not shrink has the same porosity before and after curing or solidification.

The adhesive composition or the adhesive sheet of the present invention can be suitably used in the manufacturing process of a multilayer wiring board, particularly a multilayer wiring board for high frequency use, and also for bonding electronic parts, heat resistant films and the like.

[0038]

EXAMPLES Examples and the like specifically showing the constitution and effects of the present invention will be described below. In addition, each evaluation value of the adhesive layer,
It measured as follows.

(1) Porosity of Adhesive Layer The porosity of the adhesive layer was determined from the density of the material of the porous resin particles, the density of the solid material of the base material, the weight ratio of both, and the volume and weight of the adhesive layer.

(2) relative permittivity (ε / ε ₀ ) of the porous film,
In the region of dielectric loss tangent of 10 GHz, a vector network analyzer (HP87220) and a cavity resonator (Kanto Electronics Co., Ltd.) were used to measure by the perturbation method, and each measurement point 10
It was calculated from the average of the times.

(Particle Preparation Example 1) 51,000 g (0.2 mol) of 4,3,3 ', 4,4'-biphenyltetracarboxylic dianhydride in a 1,000 mL four-necked flask under a nitrogen gas atmosphere, 4,4 '-Diaminodiphenyl ether 40.0
g (0.2 mol), N-methyl-2-pyrrolidone 395
g was charged and reacted at room temperature with stirring at 150 rpm for 5 hours to polymerize a highly viscous polyamic acid. The weight average molecular weight of the polyamic acid was 57,000. 20 g of xylene was added to this polymerization solution, and the temperature was slowly raised. Dehydration started at around 160 ° C., the temperature was raised to 190 ° C., and this temperature was maintained for 3 hours to confirm the completion of the dehydration reaction. Further, xylene was distilled off at 195 ° C. At this time, the polymerization solution was a yellow and transparent homogeneous solution. When the polymerization solution was cooled at a slow cooling rate of 30 ° C./10 minutes at this stirring speed, the polymerization solution began to become turbid from around 180 ° C., and precipitation of polyimide was observed. After cooling to room temperature as it was and stopping stirring, the precipitate was separated by filtration and washed with a large amount of methanol. The filtered polyimide was heated and dried in a dryer at 100 ° C. to obtain yellow polyimide powder.

From the infrared absorption spectrum (KBr method) of this polyimide powder, 1775 cm ^-1 and 1715 cm ^-1
Carbonyl absorption based on imide group was observed. The fine particles of this polyimide powder are 5 to 1 according to the SEM photograph.
The particles were spherical particles having a diameter of 0 μm, but there were few independent particles and they were aggregates (average primary particle diameter: about 20 μm). In addition, many leafs were piled up on the surface. This powder particle has 2θ = 15.08, 2 by wide-angle X-ray diffraction.
Crystal peaks were found at 1.06 and 25.4. In addition, as a result of thermal analysis by DSC, the melting point of this crystal was 44.
It was 6 ° C. This polyimide powder did not dissolve in a polar organic solvent containing NMP at room temperature. The bulk density was 0.36 g / cm ³ .

Example 1 20 g of a polyimide-based adhesive (UPA-AH, manufactured by Ube Industries, Ltd., solid content concentration 20% by weight, viscosity 0.4 Pa · s) was added to 20 g of the porosity obtained in Particle Production Example 1. 4 g of high-quality polyimide powder was mixed and stirred for 1-2 minutes with a rotation / revolution hybrid mixer (manufactured by KEYENCE CORPORATION) to uniformly disperse. The obtained adhesive composition was applied onto a glass plate with an applicator so as to have a thickness of 100 μm, and dried at 90 ° C. for 30 minutes to obtain an adhesive sheet. This was further cured at 140 ° C. for 1 hour to obtain a sheet corresponding to the adhesive layer. SEM observation of the cross section of this sheet confirmed that voids were formed in the porous portion of the porous resin particles. The porosity of this sheet was 23%, the relative dielectric constant (ε / ε ₀ ) was 2.74, and the dielectric loss tangent was 0.022. The relative permittivity (ε / ε ₀ ) of the polyimide powder material was 3.0 and the dielectric loss tangent was 0.005.

Example 2 An adhesive composition was prepared in the same manner as in Example 1 except that 8 g of the porous polyimide powder was mixed, and a sheet corresponding to the adhesive layer was obtained. . The porosity of this sheet was 30%, the relative dielectric constant (ε / ε ₀ ) was 2.67, and the dielectric loss tangent was 0.0187.

Comparative Example 1 An adhesive composition was prepared in the same manner as in Example 1 except that the polyimide powder was not used, and then a sheet corresponding to the adhesive layer was obtained.
The relative permittivity (ε / ε ₀ ) of this sheet was 3.0 and the dielectric loss tangent was 0.028.

   ─────────────────────────────────────────────────── ─── Continued front page    (72) Inventor Kenichi Ikeda             1-2 1-2 Shimohozumi, Ibaraki City, Osaka Prefecture Nitto             Electric Works Co., Ltd. (72) Inventor Yasufumi Miyake             1-2 1-2 Shimohozumi, Ibaraki City, Osaka Prefecture Nitto             Electric Works Co., Ltd. F-term (reference) 4J004 AA10 AA11 AA13 AA16 AB05                       BA02 EA06 FA05                 4J040 EC001 EE001 EE061 EG001                       EH021 EH031 EH032 EJ021                       JB02 KA03 KA42 LA06 LA08                       LA09 MA03 MB05 NA20 PA23                 5E346 AA16 AA23 CC41 DD02 GG02                       GG28 HH06

Claims (6)

[Claims] 1. An adhesive composition in which a filler is dispersed in a base material containing an adhesive component, wherein the filler is porous resin particles, and the resin constituting the porous resin particles is at 10 GHz. The adhesive composition is characterized in that the relative dielectric constant of is less than or equal to the relative dielectric constant of the solid content of the base material. 2. The base resin solid content of the porous resin particles is 10.
The adhesive composition according to claim 1, which is contained in an amount of 10 to 300 parts by weight with respect to 0 parts by weight and has an average primary particle diameter of 0.05 to 20 μm. 3. The adhesive composition according to claim 1, wherein the resin forming the porous resin particles is an aromatic polyimide, and the adhesive component contains a thermosetting component. 4. The adhesive composition according to claim 1, wherein the adhesive component contains a polyimide precursor. 5. An adhesive sheet obtained by molding the adhesive composition according to claim 1 into a sheet. 6. The adhesive sheet according to claim 5, which is used for manufacturing a multilayer wiring board.