JP2019155666A - Resin substrate - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a resin substrate which improves thermal conductivity without lowering adhesion strength. A resin substrate (10) is formed by heating and pressing a semi-cured prepreg and a metal foil (19) by holding a thermosetting resin composition (12) containing an inorganic filler on a fiber base material (15). The length of the long side of the base material 15 is t, and the area of the surface of the resin substrate 10 in the range of 15 t in length and 20 t in width is 100 area% at the interface between the metal foil 19 and the cured product derived from prepreg. And the area ratio of the element concentration of the elements other than oxygen derived from the inorganic filler is 10% or less is 5 to 60 area %. [Selection diagram] Figure 1

Description

  The present invention relates to a resin substrate.

In recent years, the number of electronic devices mounted on automobiles has been increasing, and miniaturization of these electronic devices has been progressing rapidly. On the other hand, the amount of heat generated from a high-density conductor is increasing with downsizing, and how to dissipate heat is an important issue.
As a technology to improve the heat dissipation of printed circuit boards using conventional glass-epoxy resin, a copper plate is used on a metal base substrate that forms a circuit pattern on one or both sides of a metal substrate via an insulating layer, and a ceramic substrate such as alumina or aluminum nitride. There has been proposed a substrate in which these are directly bonded. It is difficult to balance the metal base substrate and the ceramic substrate in terms of performance and cost.
And in order to obtain the heat dissipation of the resin substrate, a resin composition in which the resin viscosity is lowered and the inorganic filler is filled at a high concentration, and a resin substrate have been proposed. For example, Patent Document 1 discloses a heat conductive sheet-like material that can be filled with an inorganic filler at a high concentration and excellent in heat dissipation and a heat conductive substrate using the same, and requires heat dissipation. It is thought that it is suitable for the substrate use.

Japanese Patent No. 3312723

  However, in a resin substrate filled with an inorganic filler as described in Patent Document 1 at a high concentration, the adhesion to a metal foil such as a copper foil is hindered by the inorganic filler, and the adhesion strength to the metal foil is low. There is a problem that it decreases.

  This invention is made | formed in view of the said situation, and it aims at providing the resin substrate which improves a heat conductivity, without reducing adhesive strength.

  In order to solve the above problems, the present inventors provide the following means.

[1] A resin substrate formed by heating and pressing a prepreg and a metal foil that are held in a fiber base material and include a thermosetting resin composition containing an inorganic filler,
The length of the long side of the opening of the fiber base material is t, and the area of the surface of the resin substrate in the range of 15t and 20t is 100 at the interface between the metal foil and the cured product derived from the prepreg. A resin substrate, wherein the area ratio of elements other than oxygen derived from the inorganic filler when the area percentage is 10% or less is 5 to 60 area%.
[2] When the length of one side of the opening of the fiber base material is t and the area of the surface of the resin substrate in the range of length 15t and width 20t is 100% by area, it is derived from the inorganic filler. The resin substrate according to [1], wherein the area ratio of elements other than oxygen having an element concentration of 10% or less is 20 to 50 area%.
[3] The resin substrate according to [1] or [2], wherein the prepreg includes a prepreg having a void on the surface.

  By creating a portion with a small amount of inorganic filler on the surface of the resin substrate of the present invention, the adhesion strength between the metal foil and the resin is increased, and the peel strength (peel strength) of the metal foil is increased. In addition, there are places where a large amount of inorganic filler exists on the substrate surface, and this part becomes a heat conduction path, so that the thermal conductivity is increased. It is possible to provide a resin substrate that improves the thermal conductivity without reducing the adhesion strength.

It is sectional drawing showing the structure of the resin substrate of one Embodiment of this invention. It is sectional drawing for demonstrating an example of the manufacturing method of the board | substrate of one Embodiment of this invention. It is sectional drawing showing the structure of the resin substrate of an Example.

  Hereinafter, the present embodiment will be described in detail with appropriate reference to the drawings. In the drawings used in the following description, in order to make the characteristics of the present invention easier to understand, there are cases where the characteristic parts are enlarged for the sake of convenience, and the dimensional ratios of the respective components are different from actual ones. is there. The materials, dimensions, and the like exemplified in the following description are examples, and the present invention is not limited to them, and can be appropriately modified and implemented without departing from the scope of the invention.

(Resin substrate)
The resin substrate of the present invention is a resin substrate formed by heating and pressurizing a prepreg and a metal foil which are held in a fiber base material by holding a thermosetting resin composition containing an inorganic filler in a semi-cured state. The length of the long side of the opening of the material is t, and at the interface between the metal foil and the cured product derived from the prepreg, the area of the surface of the resin substrate in the range of 15t length and 20t width is 100% by area. The area ratio of the element concentration of the element excluding oxygen derived from the inorganic filler is 10% or less is 5 to 60 area%. Moreover, the area ratio of the element concentration of elements other than oxygen derived from the inorganic filler is preferably 10 to 50% by area, more preferably 30 to 50% by area.
When the metal foil and the cured product derived from the prepreg have a portion with a small amount of inorganic filler (inorganic filler sparse part), the adhesion strength between the metal foil and the resin is increased, so that the peeling strength of the metal foil is increased. (Peel strength) increases. In addition, when there is a portion with a small amount of inorganic filler at the interface between the metal foil and the cured product derived from the prepreg, there is a portion where there is a large amount of filler, and this portion becomes a heat conduction path. The rate is high. In addition, since there are few resin and a location with few inorganic fillers is less than 5%, peel strength does not go up. If the proportion of the inorganic filler is less than 60%, the resin portion having a low thermal conductivity is increased, and the thermal conductivity is lowered. Moreover, thermal conductivity is higher that the location with few inorganic fillers is 20-50 area%.

<Configuration of resin substrate>
FIG. 1 is a cross-sectional view illustrating a configuration of a resin substrate 10 according to an embodiment of the present invention. The resin substrate 10 of the present embodiment is a resin formed by heating and pressurizing one prepreg and a metal foil 19 that are held in a fiber base material 15 and containing a thermosetting resin composition containing an inorganic filler. It is a substrate. The resin substrate 10 of the present embodiment includes a cured product 12 of a thermosetting resin composition and a fiber base material 15. The cured product 12 of the thermosetting resin composition is obtained by curing a thermosetting resin composition containing an inorganic filler, and is composed of an inorganic filler and a cured product of the thermosetting resin.

<Inorganic filler sparse part>
The resin substrate 10 of the present embodiment is characterized by having a portion (inorganic filler sparse portion) 18 with a small amount of inorganic filler at the interface between the cured product 12 of the thermosetting resin composition and the metal foil 19. The length of the long side of the opening of the fiber base material 15 is t, and at the interface between the metal foil and the cured product derived from the prepreg, the area of the surface of the resin substrate 10 in the range of 15t length and 20t width Is 100 area%, the area ratio of the inorganic filler sparse part 18 is 5 to 60 area%. The portion (inorganic filler sparse portion) 18 having a small amount of the inorganic filler of the present invention is a portion in which elements derived from the inorganic filler excluding oxygen and the fiber base are 10% or less.

“Ingredients of sparse inorganic filler”
The components of the inorganic filler sparse part 18 are not particularly limited as long as the effects of the thermal conductivity and adhesion strength of the resin substrate of the present invention can be achieved, but from the viewpoint of easy manufacture, the inorganic filler sparse part 18 The cured product of the resin composition preferably includes the same type of thermosetting resin and inorganic filler material as the cured product of the surrounding resin composition.

“Arrangement of sparse inorganic filler”
The arrangement (distribution) of the inorganic filler sparse portion 18 of the present embodiment is not particularly limited as long as there is an effect of the thermal conductivity and adhesion strength of the resin substrate, but is preferably dispersed.

“Size of sparse part of inorganic filler”
The size of the inorganic filler sparse part 18 of the present embodiment is not particularly limited as long as the thermal conductivity and adhesion strength of the resin substrate are effective. For example, the inorganic filler sparse part 18 of the present embodiment is a resin In the cut surface in the thickness direction of the substrate 10, as shown in FIG. 1, the width is preferably equal to or smaller than the opening diameter of the fiber base material.

“Shape of sparse part of inorganic filler”
The shape of the inorganic filler sparse part 18 of the present embodiment is not particularly limited as long as it has effects of the thermal conductivity and adhesion strength of the resin substrate. For example, the inorganic filler sparse part 18 of the present embodiment is a resin On the cut surface in the thickness direction of the substrate 10, as shown in FIG. 1, the lateral width parallel to the substrate surface is preferably substantially elliptical or flat (disk shape) larger than the thickness parallel to the substrate thickness.

<Resin substrate manufacturing method>
The laminated substrate of this embodiment is obtained by curing a prepreg.
In one embodiment of the method for producing a resin substrate of the present embodiment, first, as shown in FIGS. 2A to 2B, for example, by using a prepreg 21 having a void and a metal foil 29, hot pressing / molding is performed. The substrate 20 can be formed by the process.

Specifically, the resin substrate 20 of the present embodiment can be formed by a hot pressing / molding process so as to face the side surface of the prepreg 21 having a void and the metal foil 29.
When the prepreg 21 having a void and the metal foil 29 are laminated to produce the resin substrate 20, the resin preferentially flows into the void portion to fill the void, so that the portion having the void has a small amount of inorganic filler. (Inorganic filler sparse portion 28) is generated, and a portion with a lot of inorganic filler is generated around a portion having a void.
The size of the gap of the prepreg 21 is preferably smaller than the opening of the fiber base 25. If there are many voids larger than the openings of the fiber base 25, the area of the sparse portion of the inorganic filler per prepreg becomes large, and heat conduction may be difficult to be transmitted.

  The conditions for pressing and molding the prepreg 21 and the metal foil 29 to form the resin substrate 20 are as follows. If the uncured / semi-cured thermosetting resin of the prepreg 21 is cured to form the inorganic filler sparse part 28, There is no particular limitation. Usually, it is the range of 100 to 250 degreeC, Preferably it is the range of 130 to 230 degreeC. Moreover, the pressurization conditions in a heating and pressurizing process are not specifically limited. Usually, it is in the range of 1 MPa to 20 MPa, preferably in the range of 1 MPa to 15 MPa. Moreover, a vacuum press is used suitably for a heating and pressurizing process.

  The metal foil is not particularly limited, and can be appropriately selected from commonly used metal foils. Specifically, gold foil, copper foil, aluminum foil, etc. can be mentioned, and copper foil is generally used. The thickness of the metal foil is not particularly limited as long as it is 1 μm to 200 μm, and a suitable thickness can be selected according to the electric power used.

  Further, as the metal foil, nickel, nickel-phosphorus, nickel-tin alloy, nickel-iron alloy, lead, lead-tin alloy or the like is used as an intermediate layer, and a copper layer of 0.5 μm to 15 μm and 10 μm to A three-layer composite foil provided with a 150 μm copper layer, or a two-layer composite foil in which aluminum and copper foil are combined can also be used.

  The metal plate is preferably made of a metal material having a high thermal conductivity and a large heat capacity. Specific examples include copper, aluminum, iron, and alloys used for lead frames.

  The plate | board thickness of the said metal plate can be suitably selected according to a use. For example, the material of the metal plate can be selected according to the purpose, such as aluminum when priority is given to weight reduction and workability, and copper when priority is given to heat dissipation.

  In the said board | substrate 10, in order to raise metal foil (copper foil) peel strength, there may exist the pre-process of surface-treating metal foil by the conventionally well-known method.

In the example shown in FIG. 2, the number of the prepregs 21 is one, but the number is not limited to one and may be two or more. This number can be set as appropriate based on conditions such as the thickness and strength of the prepreg 21.
The metal foil may be provided not only on one side but on both sides, and when there are two or more prepregs, a laminated substrate in which the metal foil is laminated inside the substrate (interface between the prepreg and the prepreg) may be used. Moreover, any one type or two or more types of various processes such as an etching process and a drilling process may be performed as necessary.

<Method for producing prepreg having voids>
A prepreg having a void used for manufacturing a resin substrate according to an embodiment of the present invention is a resin composition prepared by mixing a thermosetting resin and an inorganic filler, and a slit die is formed from one side of a fiber substrate such as a glass cloth. In a coating method in which the resin composition is held on the fiber base by passing it through the opening of the fiber base and passing through the opening of the fiber base, a slit die nozzle to the fiber base such as glass cloth By controlling the indentation amount, the contact angle, and the discharge amount of the paint, the amount of the paint passing through the openings of the fiber substrate such as glass cloth can be reduced, and a prepreg having a void on the back surface of the coating can be produced.

  Other methods for forming voids in the prepreg include addition of a foaming agent that vaporizes at a semi-curing temperature, processing of a concave putter on the prepreg surface (embossing), and the like. In that case, it is preferable that the back surface of the part which became the space | gap does not become convex, or the circumference | surroundings of a space | gap do not become convex. In addition, the addition of organic fillers (particles) makes it possible to produce an inorganic filler sparse part. For example, after making a second prepreg that does not have a void, which will be described later, press a sword-shaped projection on one side to create irregularities, and then flatten the convex part by pressing a flat plate. For example, voids can be formed.

  Specifically, as the resin composition, for example, when each of the epoxy resin and the curing agent contained in the resin composition described later is solid, the resin composition is pulverized into a powder and mixed. A prepreg can be obtained by heating and melting the product and applying the molten resin composition.

  Moreover, as a resin composition, when a solvent such as methyl ethyl ketone or cyclohexanone is added to the resin composition to form a resin composition paint, the resin composition paint is applied. Thereafter, the prepreg can be obtained by removing the solvent by drying and solidifying the resin composition.

  The content rate of the said resin composition in a prepreg is not specifically limited. From the viewpoint of moldability, it is preferably 20 vol% or more, more preferably 30 vol% or more. Further, from the viewpoint of alignment accuracy and dimensional accuracy of the multilayer substrate, it is preferably 80 vol% or less, more preferably 70 vol% or less, and further preferably 60 vol% or less.

The drying method is not particularly limited as long as at least a part of the organic solvent contained in the paint can be removed, and can be appropriately selected from commonly used drying methods according to the organic solvent contained in the paint. In general, a heat treatment method at about 60 ° C. to 150 ° C. can be exemplified.
Solidification at this time means that the liquid material having fluidity changes to a solid state in which it can stand on its own. A state in which the organic solvent contained in the paint partially remains and a semi-cured state can be included in the solidified state. For example, it can be solidified at 60 to 150 ° C. for about 1 to 120 minutes, preferably at 70 to 120 ° C. for about 3 to 90 minutes.

  When the prepreg is prepared using a resin composition paint, the solvent residual ratio in the prepreg is preferably 2.0% by mass or less, more preferably 1.0% by mass or less, and 0.8 More preferably, it is at most mass%.

  The solvent residual rate is determined from the change in mass before and after drying when the prepreg is cut into 40 mm square and dried in a thermostat preheated to 190 ° C. for 2 hours.

<Fiber base>
The prepreg having voids used for the resin substrate of the present embodiment is composed of a resin composition and a fiber base material. The fiber base material used for the resin substrate of the present embodiment is not particularly limited as long as it is usually used when producing a metal foil-clad laminated substrate or a multilayer printed wiring board, and is usually a fiber substrate such as a woven fabric or a nonwoven fabric. A material is used.

  The opening of the fiber base material according to the present embodiment is not particularly limited. From the viewpoint of thermal conductivity and insulating properties, the mesh opening is preferably twice or more the average particle diameter (D50) of the filler. Moreover, it is preferable that the porosity of a fiber base material is 30% or more. The porosity of a fiber base material is the ratio of the area of the opening part with respect to the area of a fiber base material.

  The material of the fiber base material is not particularly limited. Specifically, inorganic fibers such as glass, alumina, boron, silica alumina glass, silica glass, tyrano, silicon carbide, silicon nitride, zirconia, aramid, polyether ether ketone, polyether imide, polyether sulfone, carbon , Organic fibers such as cellulose, and mixed papers thereof. Among these, glass fiber woven fabric (glass cloth) is preferably used. Thereby, for example, when a substrate is formed using a prepreg, a flexible and arbitrarily bendable substrate can be obtained. Furthermore, it becomes possible to reduce the dimensional change of the multilayer substrate accompanying the temperature change and moisture absorption in the manufacturing process.

  The thickness of the fiber base material according to the present embodiment is not particularly limited. From the viewpoint of imparting better flexibility, it is more preferably 75 μm or less, and from the viewpoint of impregnation, it is preferably 60 μm or less. Although the minimum of the thickness of a fiber base material is not restrict | limited in particular, Usually, it is about 10 micrometers.

<Resin composition>
The prepreg having voids used for the resin substrate of the present embodiment is composed of a resin composition and a fiber base material. This resin composition contains an inorganic filler and a thermosetting resin.

"Inorganic filler"

The inorganic filler used for the prepreg of this embodiment is any one kind or two or more kinds of particulate inorganic materials. Specific examples of the inorganic filler include magnesium oxide (MgO), aluminum oxide (Al ₂ O ₃ ) and boron nitride (BN), aluminum nitride (AlN), silica (SiO 2), and the like.
As the inorganic filler, magnesium oxide is preferable because it is inexpensive, has high thermal conductivity (42 to 60 W / (m · K)), and has high volume resistivity (> 10 ¹⁴ Ω · cm).
The average particle size of the inorganic filler is 2 to 80 μm. Measurement is performed using a known particle size measuring apparatus using a laser diffraction / scattering method (for example, “Microtrack MT-3000 type” manufactured by Nikkiso Co., Ltd.) (laser diffraction / scattering method refers to irradiating filler particles with laser light. (It is a measurement method that utilizes the fact that the intensity pattern of scattered light changes depending on the particle diameter).

The content rate of the filler contained in the resin composition is not particularly limited. The filler is preferably contained in an amount of 40% by volume to 80% by volume in the total volume of the total solid content of the resin composition. In the resin composition, when the filler is contained at 40 volume% to 80 volume% in the entire volume, an effect of further increasing the thermal conductivity of the resin composition is obtained.
The content of the filler is more preferably 40% by volume to 70% by volume and further preferably 45% by volume to 60% by volume from the viewpoint of improving the thermal conductivity and fluidity.
Here, the total solid content of the resin composition means a residue obtained by removing volatile components from the resin composition.

  In addition, let the content rate (volume%) of the filler in this specification be the value calculated | required by following formula (1).

  Filler content (volume%) = (W1 / D1) / ((W1 / D1) + (W2 / D2) + Σ (Wi / Di)) × 100 (1)

Here, each variable is as follows.
W1: Mass composition ratio of filler (mass%)
W2: Mass composition ratio (mass%) of thermosetting resin
Wi: Mass composition ratio (% by mass) of each other optional solid component other than the thermosetting resin
D1: Specific gravity of the filler D2: Specific gravity of the thermosetting resin Di: Specific gravity of each other optional solid component other than the thermosetting resin

  The said filler can be used individually by 1 type or in mixture of 2 or more types. For example, two or more fillers having different D50s, which are included in the range of the average particle size (D50) of 2 μm or more and 80 μm or less, can be used in combination, but are not limited to this combination.

"Thermosetting resin"
Examples of the thermosetting resin according to this embodiment include an epoxy resin, a phenol resin, and a cyanate resin.

  The thermosetting resin of the present embodiment is not particularly limited as long as it is a compound having a thermosetting functional group, for example. Specific examples include epoxy resins, polyimide resins, polyamideimide resins, triazine resins, phenol resins, melamine resins, polyester resins, cyanate ester resins, and modified resins of these resins. These resins may be used alone or in combination of two or more.

  The thermosetting resin is preferably at least one resin selected from an epoxy resin, a phenol resin, and a triazine resin from the viewpoint of heat resistance, and more preferably an epoxy resin from the viewpoint of adhesiveness. The said epoxy resin may be used individually by 1 type, or may use 2 or more types together.

  The thermosetting resin may be a monomer or a prepolymer obtained by partially reacting the monomer with a curing agent or the like. For example, the resin having a mesogen group in the molecule is generally easy to crystallize and has a low solubility in a solvent as in the case of an epoxy resin having a mesogen group in the molecule described later, but it is polymerized by reacting partly. Since crystallization can be suppressed by making it, moldability may improve.

  It is preferable that the thermosetting resin used for the prepreg of this embodiment contains an epoxy resin.

<< Epoxy resin >>
The epoxy resin is any one kind or two or more kinds of compounds containing one or more epoxy groups (—C ₃ H ₅ O) in one molecule. Especially, it is preferable that the epoxy resin contains two or more epoxy groups in one molecule. The epoxy resin may be a monomer or a prepolymer obtained by partially reacting the monomer with a curing agent or the like.

  The type of epoxy resin is not particularly limited. For example, glycidyl ether type epoxy resin, glycidyl ester type epoxy resin, glycidyl amine type epoxy resin, novolak type epoxy resin, cyclic aliphatic type epoxy resin and long chain aliphatic type epoxy resin Etc.

  Examples of the glycidyl ether type epoxy resin include bisphenol A type epoxy resin and bisphenol F type epoxy resin. Examples of the novolac type epoxy resin include a cresol novolac type epoxy resin and a phenol novolac type epoxy resin. In addition, the type of epoxy resin may be, for example, a flame retardant epoxy resin, a hydantoin epoxy resin, an isocyanurate epoxy resin, or the like.

  In addition, the specific example of a glycidyl ether type epoxy resin will not be specifically limited if it is a compound containing the structure (group) of a glycidyl ether type. Thus, the kind is not limited as long as a specific structure is included, and the same applies to specific examples of other epoxy resins such as a glycidyl ester type epoxy resin.

  Especially, it is preferable that the epoxy resin contains the mesogenic skeleton in one molecule. The reason is as follows.

  First, since the benzene rings easily overlap each other in the molecules of the epoxy resin, the distance between the benzene rings becomes small. Thereby, the density of an epoxy resin improves in the resin composition containing an epoxy resin. In addition, since the cured epoxy resin is less likely to scatter molecular lattice vibration, high thermal conductivity can be obtained.

  The “mesogenic skeleton” is a general term for an atomic group including two or more aromatic rings and having rigidity and orientation. Specifically, the mesogenic skeleton is, for example, a skeleton that includes two or more benzene rings and in which the benzene rings are bonded to each other through either a single bond or a non-single bond.

  When three or more benzene rings are bonded, the direction of bonding is not particularly limited. That is, three or more benzene rings may be bonded so as to be linear, or may be bonded so as to be bent one or more times in the middle, or bonded so as to branch in two or more directions. May be.

  “Non-single bond” is a generic name for a divalent group containing one or more constituent elements and one or more multiple bonds. Specifically, the non-single bond includes, for example, any one or more of constituent elements such as carbon (C), nitrogen (N), oxygen (O), and hydrogen (H). . Non-single bonds include one or both of double bonds and triple bonds as multiple bonds.

  The mesogen skeleton may contain only a single bond, may contain only a non-single bond, or may contain both a single bond and a non-single bond as the type of bond between benzene rings. . Further, the number of non-single bonds may be only one, or two or more.

  Specific examples of the mesogenic skeleton include biphenyl and terphenyl. The terphenyl may be o-terphenyl, m-terphenyl, or p-terphenyl.

  As a specific example of the thermosetting resin used for the prepreg of the present embodiment, for example, YL-6121H manufactured by Mitsubishi Chemical Corporation (tetramethylbiphenol type epoxy resin 50%, 4,4′-biphenol type epoxy 50% mixture, epoxy Equivalent 175 g / eq), Nippon Kayaku Co., Ltd. BREN105 (brominated polyfunctional epoxy resin, epoxy equivalent 271 g / eq), Nippon Steel & Sumikin Chemical Co., Ltd. YH434L (tetrafunctional polyglycidylamine, epoxy equivalent 122 g / eq), DIC Examples include 830-S (bisphenol F type epoxy resin, epoxy equivalent 173 g / eq), FX289Z (phosphorus-modified epoxy resin, epoxy equivalent 225 g / eq) manufactured by Nippon Steel & Sumikin Chemical Co., Ltd., and the like.

The thermosetting resin is preferably contained in an amount of 20% by volume to 60% by volume in the total volume of the total solid content of the resin composition from the viewpoint of moldability, adhesiveness, and thermal conductivity, and is 30 volumes. It is more preferable that it is contained in% to 60% by volume, and it is more preferable that it is contained in 40% to 55% by volume.
In addition, when the said resin composition contains the below-mentioned hardening | curing agent and hardening accelerator, the content rate of these hardening | curing agents and hardening accelerator shall be included in the content rate of a thermosetting resin here.

"Curing agent"
It is preferable that the resin composition of this embodiment further contains at least one curing agent. The curing agent is not particularly limited as long as the thermosetting resin can be thermoset. Examples of the curing agent when the thermosetting resin is an epoxy resin include polyaddition curing agents such as acid anhydride curing agents, amine curing agents, phenol curing agents, and mercaptan curing agents, and imidazole. And the like, and the like.
Among these, from the viewpoint of heat resistance, it is preferable to use at least one selected from amine-based curing agents and phenol-based curing agents, and from the viewpoint of storage stability, it is preferable to use at least one phenol-based curing agent. More preferred.

  As the amine curing agent, those usually used can be used without particular limitation, and those commercially available may be used. Among these, a polyfunctional curing agent having two or more functional groups is preferable from the viewpoint of curability, and a polyfunctional curing agent having a rigid skeleton is more preferable from the viewpoint of thermal conductivity.

  Examples of the bifunctional amine-based curing agent include 4,4′-diaminodiphenylmethane, 4,4′-diaminodiphenyl ether, 4,4′-diaminodiphenyl sulfone, 4,4′-diamino-3,3′-dimethoxybiphenyl. 4,4′-diaminophenylbenzoate, 1,5-diaminonaphthalene, 1,3-diaminonaphthalene, 1,4-diaminonaphthalene, 1,8-diaminonaphthalene and the like. Among these, from the viewpoint of thermal conductivity, at least one selected from 4,4′-diaminodiphenylmethane and 1,5-diaminonaphthalene is preferable, and 1,5-diaminonaphthalene is more preferable.

  As a phenol type hardening | curing agent, what is normally used can be especially used without a restriction | limiting, The commercially available low molecular phenol compound and the phenol resin which made them novolak-ized can be used.

  Examples of the low molecular weight phenol compound include monofunctional compounds such as phenol, o-cresol, m-cresol and p-cresol, bifunctional compounds such as catechol, resorcinol and hydroquinone, and 1,2,3-tri Trifunctional ones such as hydroxybenzene, 1,2,4-trihydroxybenzene, 1,3,5-trihydroxybenzene, 1,3,5-tris (4-hydroxyphenyl) benzene can be used. In addition, a phenol novolac resin obtained by connecting these low molecular phenol compounds with a methylene chain to form a novolak can also be used as a curing agent.

  As the phenol-based curing agent, 1,3,5-tris (4-hydroxyphenyl) benzene, which is a polyfunctional low-molecular phenol curing agent, is preferable from the viewpoint of thermal conductivity, heat resistance, solvent solubility, and the like.

  When the resin composition of the present embodiment includes a curing agent, the content of the curing agent in the resin composition is not particularly limited. For example, when the curing agent is an amine curing agent, the ratio of the active hydrogen equivalent (amine equivalent) of the amine curing agent to the epoxy equivalent of the epoxy resin (amine equivalent / epoxy equivalent) is 0.5 to 2. It is preferable that it will become 0.8-1.2. Further, when the curing agent is a phenolic curing agent, the ratio of the active hydrogen equivalent of the phenolic hydroxyl group (phenolic hydroxyl group equivalent) to the epoxy equivalent of the mesogen-containing epoxy resin (phenolic hydroxyl group equivalent / epoxy equivalent) is 0. 0.5 to 2 is preferable, and 0.8 to 1.2 is more preferable.

"Curing accelerator"
When using a phenol type hardening | curing agent in the resin composition of this embodiment, you may use a hardening accelerator together as needed. By using a curing accelerator in combination, it can be further sufficiently cured. Although the kind and compounding quantity of a hardening accelerator are not specifically limited, An appropriate thing can be selected from viewpoints, such as reaction rate, reaction temperature, and storage property. Specific examples of the curing accelerator include imidazole compounds, organic phosphorus compounds, tertiary amines, and quaternary ammonium salts. These may be used alone or in combination of two or more.

  When the resin composition contains a curing accelerator, the content of the curing accelerator in the resin composition is not particularly limited. From the viewpoint of moldability, it is preferably 0.5% by mass to 1.5% by mass of the total mass of the thermosetting resin and the curing agent, more preferably 0.5% by mass to 1% by mass, More preferably, it is 0.75 mass%-1 mass%.

"Silane coupling agent"
The resin composition preferably further includes at least one silane coupling agent. As an effect of adding a silane coupling agent, it plays a role of forming a covalent bond between the surface of the filler or the second filler and the thermosetting resin surrounding it (equivalent to a binder agent) It contributes to the improvement of insulation reliability by preventing the penetration of moisture and the function of transmitting efficiently.

  It does not specifically limit as a kind of said silane coupling agent, You may use a commercially available thing. Considering the compatibility with thermosetting resins (preferably epoxy resins) and curing agents contained as necessary, and reducing thermal conduction defects at the interface between the resin and the filler, in the present invention It is preferable to use a silane coupling agent having an epoxy group, amino group, mercapto group, ureido group, or hydroxyl group at the terminal. These silane coupling agents may be used alone or in combination of two or more.

"Other ingredients"
The resin composition in the present invention can contain other components as necessary in addition to the above components. For example, an elastomer, a dispersing agent, etc. are mentioned. Examples of the elastomer include an acrylic resin, and more specifically, a homopolymer or a copolymer derived from (meth) acrylic acid or a (meth) acrylic ester. Examples of the dispersant include Ajinomoto Finetech Co., Ltd. Ajisper series, Enomoto Kasei Co., Ltd. HIPLAAD series, Kao Corporation homogenol series, and the like. Two or more kinds of these dispersants can be used in combination.

<Paint of resin composition>
For example, when a solid thermosetting resin is used as the resin composition, at least one organic solvent may be added to adjust the coating composition of the resin composition. By including an organic solvent, it can be adapted to various molding processes. As the organic solvent, a commonly used organic solvent can be used. Specific examples include alcohol solvents, ether solvents, ketone solvents, amide solvents, aromatic hydrocarbon solvents, ester solvents, nitrile solvents, and the like. For example, methyl isobutyl ketone, dimethylacetamide, dimethylformamide, dimethyl sulfoxide, N-methyl-2-pyrrolidone, γ-butyrolactone, sulfolane, cyclohexanone, methyl ethyl ketone and the like can be used. These may be used alone or as a mixed solvent using two or more kinds in combination.

<Semi-cured resin composition>
The semi-cured resin composition of the present invention (sometimes simply referred to as “resin composition”) is derived from the resin composition, and is obtained by semi-curing the resin composition. For example, when the semi-cured resin composition is molded into a sheet, the handleability is improved as compared with a resin composition sheet made of a resin composition that is not semi-cured. From that viewpoint, it is preferable that the resin composition comprised by the prepreg of this embodiment is a semi-hardened resin composition.

Here, the semi-cured resin composition means that the viscosity of the semi-cured resin composition is 10 ⁴ Pa · s to 10 ⁵ Pa · s at room temperature (25 to 30 ° C.), whereas the viscosity is 100 ° C. In, it has the characteristic that a viscosity falls rather than normal temperature. For example, the semi-cured resin composition can maintain a sheet shape at room temperature, but melts at a high temperature of about 100 ° C. Moreover, the cured resin composition after curing described later is not melted by heating. The viscosity is measured by dynamic viscoelasticity measurement (DMA) (for example, Rheo Stress 6000 manufactured by Thermo Scientific Co., Ltd.). The measurement conditions are a frequency of 1 Hz, a load of 40 g, a temperature increase rate of 3 ° C./min, and a shear test.

  Examples of the semi-curing treatment include a method of heating the resin composition at a temperature of 60 ° C. to 200 ° C. for 1 minute to 30 minutes.

<Hardened product of resin composition>
The cured product of the resin composition is derived from the resin composition, and is obtained by curing the resin composition. The cured product of the resin composition is excellent in thermal conductivity and insulation. The substrate and laminated substrate of one embodiment of the present invention are formed by curing, for example, the prepreg of the present embodiment, and curing of the resin composition formed by curing the resin composition used for the prepreg of the present embodiment. Including things.

The cured product of the resin composition can be produced by curing the uncured resin composition or the semi-cured resin composition. The method of the curing treatment can be appropriately selected according to the composition of the resin composition, the purpose of the cured product, etc., but is preferably a heating / pressurizing treatment.
For example, the resin composition in an uncured state or the semi-cured resin composition is heated at 100 ° C. to 250 ° C. for 1 hour to 10 hours, preferably 130 ° C. to 230 ° C. for 1 hour to 8 hours. A cured product is obtained.

  Embodiments of the present invention will be described in detail.

Example 1
<Preparation of first prepreg having voids>
The following materials were prepared as the resin composition.
Epoxy resin as thermosetting resin (tetramethylbiphenol type epoxy resin 50%, 4,4′-biphenol type epoxy 50% mixture, epoxy equivalent 175 g / eq, Mitsubishi Chemical Corporation YL-6121H) 60 parts by mass
Curing agent (1,3,5-tris (4-hydroxyphenyl) benzene, active hydrogen equivalent 118 g / eq), active hydrogen equivalent 59 g / eq) 40 parts by mass
Curing accelerator (2-ethyl-4-methylimidazole, 2E4MZ manufactured by Shikoku Kasei Co., Ltd.) 1 part by weight Methyl ethyl ketone as an organic solvent 50 parts by weight

  These materials were put into a medialess disperser (Desperm MD-10 manufactured by Asada Tekko Co., Ltd.) and stirred to prepare a resin mixed solution. Next, magnesium oxide powder (average particle size 30 μm, thermal conductivity 45 W / (m · K)) is added to this resin mixture as an inorganic filler, and well stirred and dispersed to produce a coating of the first resin composition. did. At this time, the magnesium oxide powder was adjusted to 60% by volume (hereinafter referred to as filling factor) when the solid content volume obtained by removing methyl ethyl ketone from the coating material of the resin composition was 100% by volume.

Furthermore, glass cloth IPC standard 1080 (non-opened glass cloth manufactured by Arisawa Manufacturing Co., Ltd., thickness 0.055 mm, mass 47 g / m ² , density 66 × 46/25 mm, plain weave type, mesh opening as fiber base material The length of the long side of 0.2 mm was used. In the coating method in which the paint of the adjusted resin composition is applied from one side of the glass cloth using a slit die, and the glass cloth is held by passing through the opening of the glass cloth through the opening of the glass cloth, By controlling the nozzle push amount of the slit die into the glass cloth to 4.7 mm, the amount of the paint passing through the opening of the glass cloth was reduced, and a prepreg having a gap on the back surface of the coating was produced. The resin preferentially flows into the prepreg voids and fills the voids, so that the voided parts have a small inorganic filler and the inorganic fillers around the voided part. There was a lot of places. As drying conditions, heat drying was performed at 100 ° C. to remove methyl ethyl ketone to obtain a first prepreg containing a resin composition layer and a glass cloth. The thickness was 172 μm.

<Preparation of second prepreg having no void>
Using the same resin composition paint as the first prepreg as the resin composition paint, using the same glass cloth as the first prepreg as the fiber base material, and using the slit die from one side of the glass cloth. In the coating method in which the coating is held on the glass cloth by applying and passing the glass cloth through the opening of the glass cloth, the glass cloth is controlled by controlling the nozzle push amount of the slit die to the glass cloth to 5 mm. The amount of paint passing through the openings was increased, and a second prepreg having no voids on the back of the coating was produced. As drying conditions, it was dried by heating at 100 ° C. to remove methyl ethyl ketone, and was cut into a length of 150 mm and a width of 150 mm to obtain a second prepreg of this example including a resin composition layer and a glass cloth. The thickness was 172 μm.

<Resin substrate>
Two obtained first prepregs having voids were used, and four second prepregs having no voids were used. The side having no void portion of the first prepreg was designated as A, the side having the void portion was designated as B, and the first prepreg was designated as AB. A second prepreg having no void portion was designated as AA. As shown in FIG. 3, the side having the void portion of the first first prepreg faces the copper foil 39A (Cu-A), and the side having the void portion of the second first prepreg is the copper foil 39B (Cu The copper foil 39A, the first first prepreg, the four second prepregs, the second first prepreg, and the copper foil 39B are connected to “Cu-A / BA / AA / AA. / AA / AA / AB / Cu-B ”, heating and pressing (temperature 170 ° C., 20 minutes at 1 MPa), and in addition, heating and pressing for the second time (temperature 200 ° C. to 4 MPa). 1 hour), the metal foil adhesion surface A (31A) which is the interface between the cured product 32 of the resin composition part and the copper foil 39A, and the metal foil which is the interface between the cured product 32 of the resin composition part and the copper foil 39B In the contact surface B (31B), the inorganic filler sparse portion 38 with a small amount of inorganic filler is formed. To obtain a resin substrate 30 to. The evaluation results are shown in Table 1.

(Examples 2 to 5, Comparative Examples 2 and 3)
<Preparation of first prepreg having voids>
Each first prepreg was prepared in the same manner as in Example 1 except that the slit die nozzle pushing amount shown in Table 1 was used.
<Resin substrate>
A resin substrate was produced in the same manner as in Example 1 except that the produced first prepreg was used. The evaluation results are shown in Table 1.

(Comparative Example 1)
A resin substrate was prepared in the same manner as in Example 1 except that the first prepreg was not used and six second prepregs were used. The evaluation results are shown in Table 1.

(Evaluation methods)
When the characteristics of each resin substrate were examined, the results shown in Table 1 were obtained. Here, at the interface between the cured product of the resin composition of each resin substrate and the copper foil, the area ratio (%) of the sparse part of the inorganic filler to the predetermined range of the substrate surface, the thermal conductivity of the resin substrate, and the adhesion strength I investigated.

<Area ratio of sparse part of inorganic filler>
The obtained metal foil of the resin substrate was removed by immersion in ferric chloride solution, washed with water and dried to expose the cured product surface of the resin composition. While observing the exposed surface with an SEM (scanning electron microscope), elemental analysis was performed with an EDX (energy dispersive X-ray analyzer) attached to the SEM, and an inorganic element containing an inorganic filler, Elemental concentrations were measured.
Next, since the length of the long side of the opening of the fiber base material (glass cloth) used in the examples is 0.2 mm, the range of 3 mm in length and 4 mm in width on the substrate surface of the base fiber contains an inorganic filler. When the element mapping is performed with the inorganic element, the portion where the element concentration of the inorganic element detected from the inorganic filler is less than 10% (sparse part of the inorganic filler) is identified, and the entire measurement range is 100 area% The area% of the sparse part of the inorganic filler was calculated.

<Thermal conductivity of resin substrate>
In order to investigate the thermal conductivity, the thermal conductivity (W / (m · K)) of the resin substrate was measured. Specifically, first, the resin substrate was cut to produce a circular measurement sample (diameter = 10 mm, thickness = 0.9 to 1.1 mm). Subsequently, the measurement sample was analyzed using a thermal conductivity measuring device (TC series manufactured by Advance Riko Co., Ltd. (formerly ULVAC Riko Co., Ltd.)), and the thermal diffusion coefficient α (m ² / s) was measured. Further, the specific heat Cp of the measurement sample was measured using differential scanning calorimetry (DSC) using sapphire as a standard sample. Furthermore, the density r of the measurement sample was measured using the Archimedes method. Finally, the thermal conductivity λ (W / (m · K)) was calculated based on the following formula (2).

λ = α × Cp × r (2)
(Λ is thermal conductivity (W / (m · K)), α is thermal diffusivity (m ² / s), Cp is specific heat (J / kg · K), and r is density (kg / m ³ ). .)

<Strength of copper foil beer on the substrate>
In accordance with JIS C6481, a test piece (150 mm × 150 mm × 10 mm) with a circuit width of 10 mm of the circuit board of the substrate was used, pulled at a speed of 50 mm / min in the direction perpendicular to the copper foil, and the peeling force was divided by the length of the width. The value was defined as the copper foil peel strength. The unit is kN / m.

<Porosity>
The prepreg voids were evaluated as porosity.
The porosity was 5 mm × 5 mm, and the back surface of the prepreg (the side having voids) was observed to determine the area of the pores relative to the area of the prepreg.
For example, when the prepreg is 5 mm × 5 mm and the holes are 0.4 mm ² , the porosity is 1.6%.
If the porosity is large, the sparse part of the filler tends to be large.

  Although the embodiments of the present invention have been described in detail with reference to the drawings, the configurations and combinations of the embodiments in the embodiments are examples, and the addition and omission of configurations are within the scope not departing from the gist of the present invention. , Substitutions, and other changes are possible.

10, 20, 30 ... resin substrate,
12, 22, 32 ... cured product of resin composition,
15, 25, 35 ... fiber base material (glass cloth),
18, 28, 38 ... sparse part of the inorganic filler,
19, 29, 39A, 39B, metal foil (copper foil)
31A: Contact surface A with metal foil 39A,
31B: adhesion surface B with metal foil 39B,
21: A prepreg having voids.

Claims (3)

A resin substrate formed by heating and pressurizing a prepreg and a metal foil in a semi-cured state by holding a thermosetting resin composition containing an inorganic filler in a fiber base,
The length of the long side of the opening of the fiber base material is t, and the area of the surface of the resin substrate in the range of 15t and 20t is 100 at the interface between the metal foil and the cured product derived from the prepreg. A resin substrate, wherein the area ratio of elements other than oxygen derived from the inorganic filler when the area percentage is 10% or less is 5 to 60 area%. When the length of one side of the opening of the fiber base material is t and the area of the surface of the resin substrate in the range of length 15t and width 20t is 100% by area, oxygen derived from the inorganic filler is excluded. 2. The resin substrate according to claim 1, wherein an area ratio of an element concentration of 10% or less is 20 to 50 area%.   The said prepreg is a resin substrate of Claim 1 or Claim 2 containing the prepreg which has a space | gap on the surface.

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