KR102375660B1 - Insulating resin material, insulating resin material with metal layer using same, and wiring board - Google Patents

Abstract

[Problem] In order to obtain an insulating resin material, which is a material that achieves both an excellent low dielectric constant and a low thermal coefficient of thermal expansion, which is difficult to obtain in the past, an insulating resin material with a metal layer and a wiring board using the same, having hollow holes 3 composed of a plurality of fine particles An insulating resin material containing a porous inorganic aggregate (2) and fibrils (4) made of polytetrafluoroethylene, wherein the fibrils (4) are oriented in multiple directions, the porous inorganic aggregate (2) and fibrils (4) Provided is an insulating resin material in which at least one of (4) is interconnected and is a fine mesh structure having a porosity of 50% or more.

Description

Insulating resin material, insulating resin material with metal layer using same, and wiring board

TECHNICAL FIELD The present invention relates to an insulating resin material, which is a material having both an excellent low dielectric constant and a low coefficient of thermal expansion, which is difficult to obtain in the past, an insulating resin material with a metal layer using the same, and a wiring board.

BACKGROUND ART With the development of electronic technology, electronic devices such as computers and mobile communication devices that use high-frequency bands are increasing. A low-dielectric constant material is generally required for high-frequency wiring boards or multilayer wiring boards used in such electronic devices, and as a low-dielectric constant resin material, for example, a non-polar polymer resin such as polyethylene, polypropylene, polystyrene, or polytetrafluoroethylene. materials can be taken.

However, since the resin material has a high coefficient of thermal expansion and is significantly different from that of a metal wiring material formed on a substrate, there are problems such as peeling and cutting of the wiring due to the difference in the coefficient of thermal expansion.

In order to achieve a low coefficient of thermal expansion of the resin material, there is a method of using an inorganic substance having a low coefficient of thermal expansion, such as filling of inorganic powder or reinforcing glass cloth. On the other hand, since the dielectric constant of an inorganic substance is generally high, there also exists a problem that the dielectric constant of the material obtained becomes high.

Then, the technique of producing a board|substrate with a low dielectric constant and a low coefficient of thermal expansion using the hollow inorganic particle whose center part of particle|grains is hollow is proposed (patent document 1).

However, when the binder is blended with the hollow inorganic particles and molded into a predetermined shape, the hollow inorganic particles are easily broken. Accordingly, since the water absorption of the insulating layer increases, when the hollow inorganic particles are used for a substrate material or a wiring board, there is a problem that the dielectric properties deteriorate. In order to improve this, the shell of the hollow inorganic particles must be enlarged, and there is a limit to obtaining an insulating resin composition having a high porosity using the hollow inorganic particles.

On the other hand, it has been proposed to dry agglomerate a fluoropolymer dispersion containing fine silica fillers having an average particle diameter of 2 µm or less to form a sheet (Patent Document 2).

However, since it is a fine silica filler, it is necessary to produce a high compression molded body, and it cannot be set as high porosity exceeding 50 %, and it is difficult to lower|reduce the dielectric constant of the material obtained.

Patent Document 1: Japanese Patent Laid-Open No. 6-119810 Patent Document 2: Japanese Patent Laid-Open No. 3-212987

However, even if these technologies are used, the lowest relative dielectric constant remains at about 1.94, and it is difficult to obtain a material having a lower dielectric constant even with other technologies.

In addition, the amount of polymer that penetrates into the roughened surface of the metal layer is insufficient, and the porous material does not penetrate sufficiently even when an inorganic filler is blended and an attempt is made to adhere to the metal by hot press or the like. , poor adhesion is also mentioned as a problem.

The present invention has been made in view of such circumstances, and provides a material having excellent low dielectric constant and low coefficient of thermal expansion, which is difficult to obtain in the prior art, and excellent in adhesion to a metal layer.

The present invention provides an insulating resin material comprising a porous inorganic aggregate composed of a plurality of fine particles and voids and fibrils made of polytetrafluoroethylene, wherein the fibrils are oriented in multiple directions, and the porous inorganic aggregate and An insulating resin material, which is a fine mesh structure in which at least one of the fibrils is interconnected and has a porosity of 50% or more, is a first aspect.

Further, the present invention provides a wiring board having an insulating resin material with a metal layer having a metal layer on at least one surface of the insulating resin material as a second aspect, and a wiring board on which a metal layer of the insulating resin material with a metal layer is patterned. do it with

Further, the metal layer is in close contact with the insulating resin material via the fluorine-based resin layer.

The inventors of the present invention have a trade-off relationship between a low dielectric constant and a low coefficient of thermal expansion, and paying attention to the long-standing problem that it is difficult to achieve both a low dielectric constant and a low coefficient of thermal expansion, aiming to achieve coexistence of a low dielectric constant and a low coefficient of thermal expansion. did careful research. As a result, as a result of repeated studies while recalling the control of the porosity of materials in the organic/inorganic composite technology, the porous inorganic aggregate with voids composed of a plurality of fine particles was firmly formed with fibrils made of polytetrafluoroethylene. By binding it, the intensity|strength of an insulating resin material was improved, discovered that the low dielectric constant and low coefficient of thermal expansion which were originally in a trade-off relationship were compatible, and came to reach this invention.

The insulating resin material of the present invention is an insulating resin material containing a porous inorganic aggregate having hollow pores composed of a plurality of fine particles and fibrils made of polytetrafluoroethylene, wherein the fibrils are oriented in multiple directions, Since at least one of the porous inorganic aggregate and the fibrils are interconnected and the fine mesh structure has a porosity of 50% or more, it is possible to achieve both an excellent low dielectric constant and a low coefficient of thermal expansion.

In addition, if the BET specific surface area of the porous inorganic aggregate is 10 to 250 m 2 /g, a strong fine mesh structure can be obtained and an excellent insulating resin material is obtained.

In addition, when the apparent specific gravity of the porous inorganic aggregate is 100 g/L or less, it is possible to obtain a stronger fine mesh structure.

Furthermore, if the average particle diameter of the fine particles constituting the porous inorganic aggregate is 5 to 35 nm, a stronger fine mesh structure can be obtained.

In addition, when the microparticles constituting the porous inorganic aggregate are porous fine powder silica subjected to hydrophobic treatment, the dielectric constant and dielectric loss tangent of the insulating resin material are stabilized, and the resulting product is excellent in precision.

Moreover, when the blending amount of the porous inorganic aggregate is 50% by weight or more with respect to the total of the porous inorganic aggregate and the fibrils, a lower coefficient of thermal expansion can be obtained, resulting in excellent product precision.

Moreover, when the dielectric constant in frequency 10 GHz of the said insulating resin material is 1.55-1.9, and a dielectric loss tangent is 0.01 or less, it will become excellent in the precision of the product obtained.

When the coefficient of thermal expansion of the insulating resin material is 10 to 50 ppm/K, the accuracy of the obtained product is further improved.

When the insulating resin material has a metal layer on at least one surface thereof, it is possible to obtain an insulating resin material with a metal layer as a substrate material which is excellent in a low dielectric constant and a low coefficient of thermal expansion.

In addition, if the metal layer is in close contact with at least one surface of the insulating resin material via the fluorine-based resin layer, the fluorine-based resin penetrates into the roughened part of the metal layer, the roughened part of the insulating resin material, and the hollow hole and anchors the anchor. It becomes possible to express the effect and to adhere strongly.

Furthermore, when the metal layer and the insulating resin material have a peeling strength of 0.6 kN/m or more via the fluorine-based resin layer, a highly reliable insulating resin material with a metal layer can be obtained.

When the metal layer of the insulating resin material with a metal layer is patterned, a wiring board excellent in reliability can be obtained.

Fig. 1 (a) is a scanning electron microscope (SEM) photograph (magnification 50000 times) enlarged in the thickness direction of the insulating resin material, which is one embodiment of the present invention, and Fig. 1 (b) is an enlarged cross section in the plane direction. It is an SEM picture (magnification of 3000x).
It is sectional drawing of the insulating resin material with a metal layer which is one of embodiment of this invention.
3 is a cross-sectional view of a wiring board which is one embodiment of the present invention.

Next, an embodiment of the present invention will be described in detail. However, this invention is not limited to this embodiment.

The insulating resin material of the present invention, as shown in the SEM photographs of Figs. It contains fibrils (4) made of fluoroethylene. And, the insulating resin material, for example, as shown in the SEM photograph of FIG. 1(b), the fibrils 4 are oriented in multiple directions, and the At least one side is interconnected and consists of a fine mesh structure having a porosity of 50% or more. In addition, in Fig.1 (a), reference|symbol 1 has shown the cross section of the fibril.

That is, the insulating resin material of the present invention is formed into a fine mesh structure by firmly binding the porous inorganic aggregate (2) having hollow holes (3) composed of a plurality of fine particles with fibrils (4) made of polytetrafluoroethylene. and has multiple pores. Hereinafter, each configuration will be sequentially described.

<Porous inorganic aggregate>

The porous inorganic aggregate used in the present invention is composed of a plurality of fine particles. In the form of the porous inorganic aggregate, the fine particles are primary particles, and they exist as agglomerates in which many are aggregated. Specifically, in the porous inorganic aggregate, a plurality of fine particles are aggregated and fused in a beads shape to form a bulky aggregate. Accordingly, the porous inorganic aggregate becomes an aggregate having voids.

The average particle diameter of the fine particles serving as the primary particles is preferably 5 to 35 nm from the viewpoint of cohesiveness, and more preferably 15 to 35 nm.

When the average particle diameter of the primary particles is less than the lower limit, the compressive strength decreases, so particle collapse tends to occur in the processing process. Also, since the space composed of a plurality of fine particles becomes small, the porosity of the insulating resin material decreases. tends to be easy.

Conversely, porous inorganic aggregates composed of fine particles having an average particle diameter exceeding the above upper limit tend to easily form irregularities on the surface of the insulating resin material, and are not suitable for high-frequency insulating resin materials that require a smoother surface. .

Here, the average particle diameter calculated|required the particle diameter of several particle|grains (100 pieces) by direct observation with a scanning electron microscope (SEM) etc., and made the average value into the average particle diameter.

According to the degree of aggregation of the primary particles, they are classified into primary aggregates and secondary aggregates, and the secondary aggregates refer to aggregates in which the primary aggregates are further aggregated. The primary agglomerates are usually 100 to 400 nm, and the secondary agglomerates are usually 1 to 100 μm.

The porous inorganic aggregate contained in the insulating resin material of the present invention is preferably a secondary aggregate from the viewpoint of easily forming a fine three-dimensional mesh structure with fine particles.

Here, the "voids" composed of a plurality of fine particles in the porous inorganic aggregate means pores in the bulky aggregate formed by aggregation and fusion of the plurality of fine particles in a beads shape. The shape of the hollow hole may be a spherical shape or an irregular shape, and is not particularly limited. In addition, since it is easy to hold an empty hole, it is preferable to consist of microparticles|fine-particles of uniform particle size.

The average pore diameter of the pores is preferably 10 to 1000 nm, and more preferably 50 to 500 nm from the viewpoint of not reducing the mechanical properties of the insulating resin material.

The said average hole diameter calculates|requires the hole diameter of several hollow hole (100 pieces) by direct observation with a scanning electron microscope (SEM) etc., and let the average value be an average hole diameter. In addition, in the case of an irregular hollow hole, let the maximum diameter of an empty hole be a hole diameter.

Further, a BET specific surface area of 10 to 250 m 2 /g of the porous inorganic aggregate is preferable from the viewpoint of easy formation of bulky aggregates, and further preferably 40 to 100 m 2 /g is particularly preferable. When it is less than the said lower limit, it becomes a flock|aggregate close|similar to a primary particle, and since the space comprised by the several microparticles|fine-particles decreases, there exists a tendency for the porosity fall of an insulating resin material to become easy to occur. On the other hand, when the upper limit is exceeded, the surface of the porous inorganic aggregate has more polar functional groups, such as OH groups, on the surface, so that contaminants such as water are attached to it, and the dielectric constant or dielectric loss tangent rises, making it easy to deteriorate the dielectric properties. Moreover, the porous inorganic aggregate cannot be firmly bound with fibrils of polytetrafluoroethylene, and cracks tend to occur in the insulating resin material obtained.

The specific surface area of the porous inorganic aggregate is determined by the BET method (a positive pressure/capacity method using nitrogen gas using gas adsorption).

In addition, the apparent specific gravity of the porous inorganic aggregate is preferably 100 g/L or less from the viewpoint of porosity, and is preferably 30 to 100 g/L, particularly preferably 50 to 60 g/L.

If the upper limit is exceeded, the primary particles have a high agglomeration density or become aggregated particles close to the primary particles, and the porosity of the porous inorganic aggregate itself decreases. there is.

On the other hand, when it is less than the said lower limit, although the porosity of the porous inorganic aggregate itself becomes high, the contact point between primary particles decreases, and there exists a tendency for compressive strength to fall. When the compressive strength is lowered, the particles of the porous inorganic agglomerate are likely to disintegrate, and good workability cannot be obtained.

For the apparent specific gravity of the porous inorganic aggregate, slowly add a predetermined amount of fine silica powder to a measuring cylinder (capacity 250 mL), measure the weight, set the value as Xg, add silica and leave it, then read the silica volume The value was YmL, and it calculated|required by apparent specific gravity (g/L)=X/Yx1000.

If the average particle diameter of the primary particles, the BET specific surface area, and the apparent specific gravity are within the preferable ranges, an insulating resin material having a lower dielectric constant and a lower coefficient of thermal expansion can be obtained.

The fine particles constituting the porous inorganic aggregate include, for example, hydrophobized porous fine powder silica, titanium oxide, and alumina. Among them, it is preferable to use hydrophobicized porous fine powder silica from the viewpoint of low dielectric constant and low coefficient of thermal expansion. Do.

The microparticles|fine-particles which comprise a porous inorganic aggregate can be used individually or in combination of 2 or more types.

In order to hydrophobize the porous fine powder silica, there is a method in which the porous fine powder silica is treated with a surface treatment agent such as dimethyldichlorosilane, hexamethyldisilazane, silicone oil, octylsilane, or the like.

The degree of hydrophobicity of porous fine powder silica can be confirmed by a powder wettability test using an aqueous methanol solution. The porous fine powder silica particles have a high degree of hydrophilicity and are wetted with water and precipitated. However, the hydrophobized porous fine powder silica particles do not settle in water, but wet and settle in methanol. The powder wettability test is a method of measuring the sediment volume by wetting porous fine powder silica particles with a high degree of hydrophobicity in the aqueous solution by changing the methanol concentration of the aqueous methanol solution using this characteristic.

In order to completely precipitate the hydrophobized porous fine powder silica used in the present invention, a methanol concentration of 30 wt % or more is required in the powder wettability test.

Examples of the hydrophobized porous fine powder silica include amorphous silica, precipitated silica, thermally decomposed silica, fumed silica, silica gel, and the like. Among them, fumed silica is preferably used from the viewpoint of a low dielectric constant and a low coefficient of thermal expansion. These can be used individually or in combination of 2 or more types.

In addition, commercially available silica may be used as the hydrophobized porous fine powder silica. Specifically, Mizukasil series (manufactured by Mizusawa Chemicals Co., Ltd.), Cyricia series (manufactured by Fujisilica), hydrophobic AEROSIL series (manufactured by Nippon Aerosil Corporation), Nipsil series (manufactured by Toso Silica), etc. can be heard Among them, as the porous fine powder silica, hydrophobic fumed silica of the hydrophobic AEROSIL series (manufactured by Nippon Aerosil Co., Ltd.) is preferable.

<Fibril>

The insulating resin material of this invention contains the fibril which consists of polytetrafluoroethylene in addition to the said porous inorganic aggregate.

As for the polytetrafluoroethylene constituting the fibrils, it is preferable to use polytetrafluoroethylene particles from the viewpoint of fibrillation in the resin composition step before producing the insulating resin material.

The average particle diameter of the polytetrafluoroethylene particles is preferably larger than the average particle diameter of the primary particles of the porous inorganic aggregate in order to facilitate fibrillation. On the other hand, if it is an aggregate of polytetrafluoroethylene particle|grains, it is preferable that it is 650 micrometers or less in particle diameter from a dispersibility viewpoint.

The fibrillation of polytetrafluoroethylene particles depends on several factors such as the magnitude of the dry shear force, temperature, the presence of any lubricating fluid between the primary particles, etc., but to be avoided during the process of rolling molding in multiple stages, which will be described later. It is preferable from the viewpoint of promoting fibrillation to form brils. When the degree of fibrillation of the polytetrafluoroethylene particles is high, it is possible to obtain a material having high mechanical strength in the structure of the obtained insulating resin material.

The fibrils contained in the insulating resin material of the present invention are oriented in multiple directions as shown in Fig. 1(b). Compared with a resin material in which fibrils are oriented in only one direction, in a resin material in which fibrils are oriented in multiple directions, a three-dimensional mesh structure is formed by fibrils, and an insulating resin material having higher mechanical strength can be obtained. .

In addition, at least one of the porous inorganic aggregate and the fibrils oriented in multiple directions are interconnected to form a fine mesh structure. The connection includes a combination of porous inorganic aggregates, fibrils, and porous inorganic aggregates and fibrils. Among them, the merging of the three-dimensional mesh structure of the porous inorganic aggregate and the three-dimensional mesh structure of the fibrils synergistically contributes to the improvement of strength and porosity of the insulating inorganic material because the mesh structures of each other are entangled and stretched vertically and horizontally. desirable.

The blending amount of the porous inorganic aggregate is preferably 50% by weight or more, and more preferably 50 to 75% by weight, particularly when the total of polytetrafluoroethylene, which is a component of the fibrils, and the porous inorganic aggregate is 100% by weight. It is preferable to blend in an amount of 55 to 70% by weight.

When the said compounding quantity is less than the said lower limit, there exists a tendency for a thermal expansion coefficient to exceed 50 ppm/K. On the other hand, when the above upper limit is exceeded, the effect by binding of the polytetrafluoroethylene and the porous inorganic aggregate becomes weak, and the moldability tends to deteriorate.

The dielectric constant and the coefficient of thermal expansion can be controlled by the mixing ratio of the porous inorganic aggregate and polytetrafluoroethylene.

The degree of interconnection of at least one of the porous inorganic aggregate and the fibrils varies depending on factors such as the amount of fibrils or the magnitude of the key shear force.

When the blending amount of polytetrafluoroethylene, which is a component of fibrils, increases, more fibrils are formed.

<Others>

The insulating resin material of the present invention may contain additional material components as needed. In order to improve the thermal conductivity and dielectric characteristics, a thermally conductive material having a low relative permittivity such as boron nitride may be added. Further, for example, in order to increase the mechanical strength, a polymer for binding the porous inorganic aggregate may be added as needed. These additional material components can be used individually or in combination of 2 or more types.

Additional material components can be added within a range whose relative dielectric constant does not exceed 1.9 in order to form the insulating resin material of the present invention.

<Manufacturing method of insulating resin material>

Next, a suitable example of the method of manufacturing the insulating resin material of this invention is demonstrated.

The manufacturing method of the insulating resin material of this invention is, for example,

(I) mixing and drying the porous inorganic aggregate and polytetrafluoroethylene in a solvent to obtain a mixed powder, adding and mixing a volatile additive to the mixed powder to prepare a paste;

(II) a step of molding a resin composition sheet using the paste;

(III) stacking the resin composition sheets and performing rolling molding in multiple stages to obtain a rolled laminated sheet;

(IV) removing the volatile additive;

(V) It is equipped with the hot-press molding process which adds intensity|strength more.

Accordingly, it is possible to obtain an insulating resin material having a fine mesh structure in which the porous inorganic aggregate and the fibrils made of polytetrafluoroethylene shown in FIG.

In the preparation of the paste in the step (I), the porous inorganic aggregate and polytetrafluoroethylene are mixed and dried in a solvent to prepare a mixed powder. Examples of the solvent used herein include lower alcohols such as water, methanol, ethanol, isopropanol and butanol, and these are used alone or in combination of two or more.

In addition, when mixing, it is preferable to use dispersion|dispersion of polytetrafluoroethylene from a dispersibility point, and well-known means, such as a drying furnace, are used for drying.

When a paste is prepared by adding a volatile additive to the above-mentioned mixed powder, the paste is composed of a porous inorganic aggregate, polytetrafluoroethylene, a volatile additive, and the It is intended to include the case of combining other auxiliary components.

As the volatile additive, a liquid having a boiling point of 300° C. or less is preferable, for example, low molecular weight hydrocarbons such as polyethylene glycol, esters, isoparaffinic hydrocarbons, hexane, and dodecane, and among them, low molecular weight hydrocarbons are preferably used. do. These volatile additives can be used individually or in combination of 2 or more types.

Next, in step (II), a plurality of resin composition sheets are prepared using the paste, and the resin composition sheets prepared in step (III) are stacked and rolled in multiple stages to form a rolled laminate sheet.

When molding the resin composition sheet in the step (II), for example, molding using a molding machine such as an FT die, a press machine, an extrusion molding machine, or a calendar roll is mentioned. Among them, molding using an FT die is particularly preferable.

The "rolling in multiple stages" in the said process (III) is demonstrated concretely below.

A plurality of (for example, 2 to 10) resin composition sheets are laminated, and this laminate is rolled to obtain a first rolled laminate sheet. Two obtained 1st rolling lamination sheets are overlapped and laminated|stacked, this laminated body is rolled, and a 2nd rolling lamination sheet is produced. Furthermore, two obtained 2nd rolling lamination sheets are overlapped and laminated|stacked, this laminated body is rolled, and a 3rd rolling lamination sheet is produced. Thus, the said lamination|stacking rolling process is repeated until the target number of constituent layers of an insulating resin material is reached. Repeating this lamination rolling process is called rolling in multiple stages.

When producing the rolled-laminated sheet, for example, molding using a molding machine such as a press machine, an extrusion molding machine, or a calendar roll is mentioned. Among them, molding using a calendar roll is preferable from the viewpoint of productivity.

As the number of constituent layers increases by rolling in multiple stages, the strength of the obtained insulating resin material can be increased, and the number of constituent layers is preferably 10 to 1000 layers.

Moreover, it is preferable that the rolling magnification of the said rolling is 100-20000 times from the point which forms many fibrils.

When repeating the said lamination|stacking rolling process, it is preferable to change a rolling direction. As a method of changing the rolling direction, for example, a plurality of sheets are rolled with the rolling directions aligned to produce a plurality of rolled laminated sheets, (1) the obtained plurality of rolled laminated sheets are aligned with the rolling directions so that the sheet surfaces are parallel A method of rolling by rotating the sheet 90 degrees in the previous rolling direction as it is, (2) A method of rolling only a part of the obtained plurality of rolled laminated sheets in parallel by rotating the sheet 90 degrees in the previous rolling direction and rolling; (3) A method of arranging only a part of the obtained plurality of rolled lamination sheets in a form folded by 180 degrees, rotating them by 90 degrees, and rolling, etc. are mentioned. By rolling while changing the direction in this way, the network of polytetrafluoroethylene is extended vertically and horizontally, and fibrils of a three-dimensional mesh structure are formed.

A molded article having a final target thickness (eg, thickness of about 0.1 to 2 mm) is produced by the multi-stage rolling, and then, the volatile additive is removed in step (IV).

The removal of the volatile additive in the step (IV) can be carried out according to a method appropriately selected from known methods according to the volatile additive to be used. Among them, the rolled laminated sheet is placed in a drying furnace or the like and heated to heat the volatile additive. It is preferable to volatilize the

In the heat press molding in the step (V), it is preferable to sinter at a temperature within the firing temperature range of polytetrafluoroethylene (for example, 300 to 500°C). Moreover, it is preferable from the point of a moldability to use a press machine as for hot press molding.

In the step (V), the porous fine powder and polytetrafluoroethylene are formed by heat-pressing molding (for example, 40 to 500° C., 0.2 to 30 MPa, 5 to 60 minutes) within the range where the porosity of the insulating resin material does not become less than 50%. It can bind more strongly.

Moreover, when manufacturing the insulating resin material with a metal layer, it has the process (VI) of forming a metal layer on at least one surface of the insulating resin material obtained by the said process (I) - the process (V) (refer FIG. 2; In addition, in Fig. 2, metal layers are provided on both upper and lower surfaces of the insulating resin material).

Furthermore, when manufacturing a wiring board, it has the process (VII) of patterning the metal layer of the said insulating resin material with a metal layer (refer FIG. 3).

As the step of forming the metal layer on at least one surface of the insulating resin material in the step (VI), for example, a method of bonding the metal layer through a resin layer for adhesion that can be softened and melted by heat such as a thermoplastic resin, copper foil, etc. A method of joining metal foils, a method of laminating, a method of sputtering or plating using a metal material, etc. are mentioned. Among these, the method of making a metal layer closely_contact|adhere via the resin layer for adhesion|attachment from an adhesive point is preferable, and the lamination method is used preferably from the point of forming a metal layer of uniform thickness.

As a method of adhering the metal layer through the above-mentioned resin layer for adhesion, first, before bonding, a resin layer for adhesion is formed between the metal layer and the insulating resin material, and then, the resin layer for adhesion is formed by heat and pressure by hot press or the like. There is a method of realizing strong adhesion due to the anchor effect by melting it and allowing the resin to penetrate into the roughened portion of the metal layer or the roughened portion and void portion of the insulating resin material. As the resin for the adhesion resin layer, adhesion is possible as long as it is a resin that is softened and melted by heat when joined to a metal, but a fluorine-based resin material is preferable from the viewpoint of dielectric properties. The fluorine-based resin is not particularly limited as long as it is a fluorine-based resin. For example, polytetrafluoroethylene (PTFE), tetrafluoroethylene-perfluoroalkylvinyl ether copolymer (PFA), tetrafluoroethylene-hexafluoro A propylene copolymer (FEP), a tetrafluoroethylene-ethylene copolymer (ETFE), polychlorotrifluoroethylene (PCTFE), etc. are mentioned, Among these, PTFE and PFA are more preferable.

As close_contact|adherence of the metal layer and the insulating resin material via the said fluororesin layer, it is preferable from a reliability point that it is 0.6 kN/m or more of peeling strength.

In addition, the mediation method of the resin layer for adhesion is a method of preparing a resin layer for adhesion by painting on the roughened part of the metal layer and drying, or a method of preparing a resin layer for adhesion by dipping or coating to an insulating resin material and drying it, hot melt Any method, such as the method of putting a film between a metal layer and an insulating resin material, may be sufficient. Moreover, as a preferable thickness of the resin layer for close_contact|adherence, when dielectric characteristics, thermal expansion, etc. are considered, it is preferable to form 10 micrometers or less.

Examples of the metal of the metal layer include gold, silver, platinum, copper, aluminum, and alloys thereof, and among them, copper is preferably used. The thickness of the metal layer is preferably 5 to 50 μm.

When the insulating resin material is a sheet-like article, the metal layer may be formed on one or both surfaces of the sheet. Examples of the patterning processing method for forming the wiring in step (VII) include an additive method using a photoresist or the like, and a subtractive method by etching.

Although the insulating resin material of this invention can be obtained as mentioned above, the manufacturing method of an insulating resin material is not limited to the above.

In the insulating resin material obtained as described above, at least one of a porous inorganic aggregate and fibrils is interconnected to form a fine mesh structure having a porosity of 50% or more.

The obtained insulating resin material is compatible with the favorable low dielectric constant and low thermal coefficient of thermal expansion.

Specifically, the dielectric constant of the insulating resin material at a frequency of 10 GHz is preferably 1.55 to 1.9, more preferably 1.55 to 1.8, from the viewpoint of the accuracy of the product to be obtained. The relative permittivity is determined by the cavity resonator perturbation method with a measurement frequency of 10 GHz.

Moreover, it is preferable that a dielectric loss tangent is 0.01 or less from the above points. The dielectric loss tangent is obtained by a cavity resonator perturbation method with a measurement frequency of 10 GHz.

It is preferable from the point of the reliability of the product obtained that it is 10-50 ppm/K as for the coefficient of thermal expansion of the said insulating resin material. The coefficient of thermal expansion is obtained by TMA (Thermal Mechanical Analysis) method using the average coefficient of thermal expansion of 30 to 100 °C as the coefficient of thermal expansion.

The insulating resin material of the present invention has both a good low dielectric constant and a low coefficient of thermal expansion, so that the insulating resin material with a metal layer in which a metal layer is formed on at least one surface of the insulating resin material is a substrate material excellent in a low dielectric constant and a low coefficient of thermal expansion becomes

In addition, the wiring board on which the metal layer of the insulating resin material with a metal layer is patterned has high precision and excellent reliability. In addition, since the wiring board of the present invention has a low relative permittivity and small variations in the relative permittivity, it is possible to increase the detection distance and improve the accuracy. do.

Example

Next, although the insulating resin material of this invention is demonstrated concretely using an Example, this invention is not limited to these Examples.

[Example 1]

As fine particles constituting the porous inorganic aggregate, hydrophobic fumed silica (manufactured by Nippon Aerosil Co., Ltd., part number "NY50", BET specific surface area 40 m / g, apparent specific gravity 60 g/L, average particle diameter of primary particles 30 nm) and poly Fluon(R) PTFE Dispersion AD939E (manufactured by Asahi Glass Co., Ltd., solid content 60% by weight) was prepared as tetrafluoroethylene (PTFE), and the porous inorganic aggregate and polytetrafluoroethylene were mixed with 60:40 in consideration of the solid content. (weight ratio) was mixed in 60% methanol aqueous solution to set it as an aggregate, and the obtained aggregate was dried and mixed powder was obtained.

To the mixed powder, dodecane was added as a volatile additive in an amount of 50% by weight of the total, and a V-type mixer was used as a mixing device, the rotation speed was 10 rpm, the temperature was 24° C., and the mixing time was 5 minutes. This mixed paste was passed through a pair of rolling rolls to obtain an oval base sheet (sheet-shaped molded article) having a thickness of 3 mm, a width of 10 to 50 mm, and a length of 150 mm. Several sheets of this base sheet were produced.

Next, two of these base sheets were laminated, and the laminate was passed between the rolling rolls and rolled to prepare a first rolled lamination sheet. Several 1st rolling lamination sheets were produced.

Next, the two 1st rolled lamination sheets were overlapped with the rolling directions aligned, and the sheet surfaces were rotated 90 degrees in the previous rolling direction while being parallel and rolled, and the 2nd rolling lamination sheet was produced. Several 2nd rolling lamination sheets were produced.

Moreover, it laminated|stacked and laminated|stacked the 2nd rolling lamination|stacking sheet of 2 sheets, and produced the 3rd rolling lamination sheet.

In this way, the step of laminating and rolling the sheets was repeated five times in total, counting from the lamination rolling of the base sheet, and then the gaps between the rolling rolls were narrowed by 0.5 mm and rolled several times to obtain a sheet having a thickness of about 0.18 mm. (the number of floors is 32).

Next, the obtained rolled laminated sheet was heated at 150 degreeC for 30 minutes, the volatile additive was removed, and the sheet|seat was produced.

The obtained sheet was press-molded at 380°C for 5 minutes at 4 MPa to obtain an insulating resin material of Example 1. Finally, a sheet having a thickness of about 0.15 mm was obtained.

The weight and volume of the insulating resin material produced as mentioned above were measured, and the porosity was computed based on the specific gravity and compounding ratio of each component.

[Example 2]

As fine particles constituting the porous inorganic aggregate, hydrophobic fumed silica (manufactured by Nippon Aerosil Co., Ltd., part number "NAX50", BET specific surface area 50 m / g, apparent specific gravity 60 g/L, average particle diameter of primary particles 30 nm) is used. Except that, an insulating resin material was produced in the same manner as in Example 1.

[Example 3]

As fine particles constituting the porous inorganic aggregate, hydrophobic fumed silica (manufactured by Nippon Aerosil Co., Ltd., part number "RY200S" BET specific surface area 95 m / g, apparent specific gravity 50 g/L, average particle diameter of primary particles 16 nm) was used except that An insulating resin material was produced in the same manner as in Example 1.

[Example 4]

An insulating resin material was produced in the same manner as in Example 1, except that the same porous inorganic aggregate was used and the porous inorganic aggregate and polytetrafluoroethylene were blended in a weight ratio of 70:30.

[Example 5]

Using hydrophobic fumed silica (Nippon Aerosil Co., Ltd. product number "RX200", BET specific surface area 165 m / g, apparent specific gravity 50 g / L, average particle diameter of primary particles 12 nm) as a porous inorganic aggregate, the porous inorganic aggregate An insulating resin material was prepared in the same manner as in Example 1, except that polytetrafluoroethylene and polytetrafluoroethylene were mixed in a weight ratio of 50:50, and dodecane was added as a volatile additive so as to account for 45% by weight of the total.

[Example 6]

Using hydrophobic fumed silica as a porous inorganic aggregate (product number "RX300", manufactured by Nippon Aerosil Co., Ltd., BET specific surface area of 230 m / g, apparent specific gravity of 50 g/L, average particle diameter of primary particles of 7 nm), porous inorganic aggregate An insulating resin material was prepared in the same manner as in Example 1 except that polytetrafluoroethylene and polytetrafluoroethylene were mixed in a weight ratio of 50:50, and dodecane was added as a volatile additive so as to account for 50% by weight of the total.

[Comparative Example 1]

As fine particles constituting the porous inorganic aggregate, hydrophobic fumed silica (manufactured by Nippon Aerosil Corporation, part number "RX50", BET specific surface area 45 m / g, apparent specific gravity 170 g/L, average particle diameter of primary particles 40 nm) is used. Except that, an insulating resin material was produced in the same manner as in Example 1.

[Comparative Example 2]

Hollow inorganic particles using "Glass Bubbles iM16K" (roundness 0.46 g/cm 3 , particle size 20 μm) manufactured by 3M, which used hollow inorganic particles instead of fine particles constituting the porous inorganic aggregate and was hydrophobized with silicone oil and polytetrafluoroethylene were mixed in methanol at a ratio of 35:65 (weight ratio) to obtain an aggregate, and the obtained aggregate was dried to obtain a mixed powder, and dodecane was added as a volatile additive so as to account for 40% by weight of the total. Except that, an insulating resin material was produced in the same manner as in Example 1.

Each sheet thus obtained was used to evaluate properties according to the method shown below. The result is shown together in Table 1 of a later stage.

<Relative permittivity, dielectric loss tangent>

The complex dielectric constant was measured by the cavity resonator perturbation method with the measurement frequency being 10 GHz, and the real part (epsilon)r' was made into the relative dielectric constant. Further, the dielectric loss tangent was obtained from the ratio (εr″/εr′) of the real part and the imaginary part (εr″).

Using a dielectric constant measuring device (“Network Analyzer N5230C” manufactured by Agilent Technology Co., Ltd. and “Cavity Resonator 10 GHz” manufactured by Kanto Denshio Yogahatsu Co., Ltd.), a stripe-shaped sample (sample size: width 2 mm × length 70) from each sheet mm) were cut out and measured.

<Coefficient of thermal expansion>

By the TMA method, the average coefficient of thermal expansion in the sheet plane direction from 30°C to 100°C was defined as the coefficient of thermal expansion (ppm/K) using a thermomechanical analyzer (manufactured by BRUKER AXS, "TMA4000SA").

<Absorption rate>

After drying the obtained insulating resin material (sample size 50 mm wide x 50 mm length) at 130 degreeC for 30 minutes, the weight before a test was measured. After immersing this in distilled water at 23°C for 24 hours, the weight was measured to determine the saturated water absorption.

From the result of Table 1 below, it is clear that all of the insulating resin materials of Examples 1-6 are materials in which favorable low dielectric constant and low thermal coefficient of thermal expansion were compatible.

On the other hand, the thing of Comparative Example 1 did not have a fine mesh structure with sufficient porosity, but resulted in a high dielectric constant.

In Comparative Example 2, since the hollow inorganic particles were pulverized, the porosity was also less than 50%, resulting in a poor coefficient of thermal expansion.

Moreover, it brought the result that the water absorption of the insulating resin material also rose.

From the comparison of Examples 1 to 6 with those of Comparative Example 2, it was found that the insulating resin material of the present invention has a low water absorption rate even in a fine mesh structure, and therefore can maintain stable dielectric constant characteristics even in a moisture absorption environment.

Then, an insulating resin material (substrate) with a metal layer in which a copper foil (Cu layer) was formed on both surfaces of the insulating resin material of the obtained Examples and Comparative Examples was prepared, and thereafter, the copper foil was etched to obtain a wiring board. Further, in the insulating resin material with a metal layer, a resin layer for adhesion described in Table 1 below is formed between the metal layer and the insulating resin material (however, in Comparative Examples 1 and 2, there is no resin layer for adhesion), It is obtained as a double-sided copper plate by press-molding a laminated sheet and bonding a metal layer to an insulating resin material.

Thus, using each obtained insulating resin material with a metal layer, according to the method shown below, the characteristic was evaluated. The results are shown together in Table 1 below.

<Metal layer peel strength>

The insulating resin material with a metal layer was tested based on JIS standard C6481 after the manufacture. A test piece with a length of about 100 mm was prepared in a state in which the metal layer was laminated with a width of 10 mm, and the metal layer portion was peeled off in a direction of 90° at a speed of 50 mm/min to determine the peel strength. At this time, as the failure mode, it is determined whether delamination is between the metal layer and the insulating resin layer (interfacial failure), the substrate is destroyed first (substrate destruction), and whether the metal layer and the insulating resin layer are in close contact with a force of 0.6 kN/m or more. Confirmed.

It turns out that the metal layer is formed in the insulating resin material with the adhesive strength (peel strength) excellent in all of the insulating resin materials with a metal layer of an Example from the result of said Table 1. And the wiring board was obtained by etching copper foil after that for the insulating resin material with a metal layer (board|substrate) of the obtained Example. Since this wiring board uses an insulating resin material that has both a good low dielectric constant and a low coefficient of thermal expansion, it has excellent reliability. could get results.

Although the said Example showed about the specific form in this invention, the said Example is only a mere illustration and is not interpreted limitedly. Various modifications apparent to those skilled in the art are intended to be within the scope of the present invention.

Since the insulating resin material of the present invention has both an excellent low dielectric constant and a low thermal coefficient of thermal expansion, it is suitable as a material for a high frequency wiring board, and can be suitably used for a millimeter wave antenna for a vehicle.

1: fibril cross section, 2: porous inorganic aggregate, 3: hollow hole, 4: fibrils

Claims (12)

An insulating resin material containing a porous inorganic aggregate having hollow pores composed of a plurality of fine particles and fibrils made of polytetrafluoroethylene, and not containing expandable microspheres, the insulating resin material comprising:
wherein the fibrils are oriented in multiple directions,
At least one of the porous inorganic aggregate and the fibrils are interconnected,
An insulating resin material having a fine mesh structure with a porosity of 50% or more. The insulating resin material according to claim 1, wherein the porous inorganic aggregate has a BET specific surface area of 10 to 250 m 2 /g. The insulating resin material according to claim 1 or 2, wherein the porous inorganic aggregate has an apparent specific gravity of 100 g/L or less. The insulating resin material according to claim 1 or 2, wherein the average particle diameter of the fine particles constituting the porous inorganic aggregate is 5 to 35 nm. The insulating resin material according to claim 1 or 2, wherein the fine particles constituting the porous inorganic aggregate are porous fine powder silica treated with hydrophobicity. The insulating resin material according to claim 1 or 2, wherein the blending amount of the porous inorganic aggregate is 50 wt% or more with respect to the total of the porous inorganic aggregate and the fibrils. The insulating resin material according to claim 1 or 2, wherein the dielectric constant at a frequency of 10 GHz is 1.55 to 1.9, and the dielectric loss tangent is 0.01 or less. The insulating resin material according to claim 1 or 2, wherein the thermal coefficient of thermal expansion is 10 to 50 ppm/K. The insulating resin material with a metal layer which has a metal layer on at least 1 surface of the insulating resin material of Claim 1 or 2. The insulating resin material with a metal layer according to claim 9, wherein the metal layer is in close contact with at least one surface of the insulating resin material via a fluorine-based resin layer. The insulating resin material with a metal layer according to claim 10, wherein the metal layer and the insulating resin material have a peeling strength of 0.6 kN/m or more through the fluorine-based resin layer. A wiring board on which the metal layer of the insulating resin material with a metal layer according to claim 9 is patterned.

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