KR20090060123A - Composite material composed of carbon material and resin and manufacturing method thereof - Google Patents

Abstract

Provided are a composite material composed of a carbon material and a resin capable of sufficiently exhibiting the original properties of the carbon material, and a suitable manufacturing method thereof.

A composite material comprising a carbon material and a graphite having a graphite or graphite structure, wherein the surface of the carbon material is modified, and the resin and the carbon material are chemically or physically bonded.

Description

COMPOSITE MATERIAL AND METHOD OF PRODUCING THE SAME}

The present invention relates to a composite material composed of a carbon material and a resin used as a prepreg or the like constituting the core portion of a wiring board, and a manufacturing method thereof.

There exists a product which contains carbon fiber in the core part of a core board | substrate in the wiring board which mounts a semiconductor element. The wiring board using the core substrate containing carbon fiber in the core part has a lower thermal expansion coefficient as compared with the wiring board using the core substrate made of glass epoxy of the prior art, and can match the semiconductor element and the coefficient of thermal expansion. The thermal stress generated between the wiring boards can be suppressed, so that it is provided as a highly reliable wiring board.

The core portion containing the carbon fiber of the core substrate is formed by superimposing a plurality of prepregs formed by impregnating the resin into the carbon fiber, heating and pressurizing them to integrate them. A core board | substrate is formed by laminating | stacking a wiring layer on both surfaces of this core part, A wiring layer can be formed on both surfaces of a core board | substrate by a buildup method, etc., and it can be set as a wiring board.

Patent Document 1: Japanese Patent Laid-Open No. 2003-273482

Patent Document 2: Japanese Patent Application Laid-Open No. 11-269362

The core part containing the carbon fiber described above has a property of having high thermal conductivity and high strength in addition to being able to have a low thermal expansion coefficient as compared with a glass epoxy substrate or the like. This high thermal conductivity and high strength are useful as characteristics of the core substrate constituting the wiring board.

In addition, organic materials having low thermal expansion and high strength include, for example, aramid fibers.

However, since aramid fibers have a low elastic modulus, when used in the core portion, the aramid fibers are dominated by the thermal expansion force of the resin substrate and thus cannot exhibit the characteristics of low thermal expansion coefficient. On the other hand, since carbon fiber has a high modulus of elasticity, the carbon fiber can exhibit the original property of low thermal expansion rate, and can exhibit the original property also in strength and thermal conductivity.

However, as in the case of constituting the core portion with a prepreg containing carbon fiber, in the resin material composed of the resin substrate and the carbon fiber, in order to sufficiently exhibit the intrinsic properties of the carbon fiber, the adhesion between the carbon fiber and the resin substrate This is a problem.

The present invention provides a composite material made of a carbon material and a resin capable of exhibiting the original properties of a carbon material such as carbon fiber and the like, as in the case of forming a wiring board containing carbon fiber in the core portion, and a suitable manufacturing method thereof. For the purpose of

The present invention has the following configuration in order to achieve the above object.

That is, a composite material composed of a carbon material and a resin having a graphite or graphite structure is characterized in that the surface of the carbon material is modified, and the resin and the carbon material are chemically or physically bonded.

In addition, the modification treatment is a method of forming an active group on the surface of a carbon material by performing a strong alkali treatment on the carbon material, for example, in order to improve the chemical bonding between the carbon material and the resin, or performing a plasma treatment or ion beam treatment on the carbon material. , Forming irregularities on the surface of the carbon material, refers to a method of improving the bond between the carbon material and the resin using the anchor action.

As a form in which the carbon material and the resin are chemically bonded, carbon atoms on the surface of the carbon material and molecules of the resin are chemically bonded, or the carbon material and the resin are carbon on the surface of the carbon material. What is bonded through the organic material or inorganic material which chemically couple | bonded with an atom can be utilized effectively.

Moreover, the composite material of the carbon material and resin which used the carbon fiber as a carbon material is especially useful at the point which has low thermal expansion coefficient and high strength.

Further, as a method for producing a composite material of a carbon material and a resin, a step of performing a reforming treatment of forming an active group chemically bonded to the resin or a site physically bonded to the resin on the surface of the carbon material having graphite or graphite structure; And a step of forming a composite material of the carbon material and the resin by bringing the resin into contact with the carbon material subjected to the modification treatment.

As the modification treatment, a method of performing a strong alkali treatment on a carbon material and a method of performing a plasma treatment on the carbon material can be effectively used.

The composite material made of the carbon material and the resin according to the present invention improves the bond between the carbon material and the resin by performing a modification treatment on the carbon material, and suppresses the slip at the interface between the carbon material and the resin, thereby reducing the carbon material. It can provide as a composite material with sufficient original characteristics.

1 is an electron micrograph showing a cross-sectional structure of a prepreg formed by impregnating a resin into a carbon fiber. In FIG. 1, the fiber part extended to the left and right shows the cross section parallel to the longitudinal direction of a carbon fiber, and the part where small dots are gathered shows the cross section perpendicular | vertical to the longitudinal direction of a carbon fiber. The part marked black in the middle of a carbon fiber is a resin part. In addition, the fiber part of the figure is formed in bundle form by gathering many strands of carbon fiber. When forming a woven fabric from carbon fibers, a method of using carbon fiber bundles in which a large number of carbon fibers are collected is common.

The prepreg shown in FIG. 1 is formed by forming a woven fabric with a carbon fiber bundle and impregnating the resin with the woven fabric, and the resin is filled in the middle of the adjacent carbon fiber bundles.

FIG. 2 is an enlarged electron micrograph of one fiber (carbon fiber bundle) made of carbon fiber. FIG. Carbon fiber obtained by calcining the resin fibers at a high temperature of about 3000 ° C. is a grade in which shallow grooves are formed on the outer surface of the fiber, and the outer surface of the fiber is very smooth. Therefore, when a prepreg is made by impregnating a resin into a woven fabric made of carbon fiber, even though the carbon fiber and the resin are in close contact with each other at first glance, the mechanical bonding between the carbon fiber and the resin is weak, and in reality, the state is hardly close. do. In addition, the graphitized carbon fiber is chemically stable and does not bond chemically with the resin.

For this reason, for example, the core portion formed by integrally heating a plurality of prepregs formed by impregnating a resin into a carbon fiber, and heating and pressurizing is excellent in the low thermal expansion rate and high strength inherent in the carbon fiber by sliding between the carbon fiber and the resin. Can not exhibit characteristics.

In the method for producing a composite material composed of the carbon material and the resin of the present invention, the carbon material is modified to improve chemical or physical bonds between the carbon material and the resin, thereby reflecting the properties of the carbon material as characteristics of the composite material. It is to be possible.

For example, the graphitized carbon fiber as a carbon material is characterized in that the carbon fiber is modified to make it easier to chemically bond the carbon fiber and the resin or to improve the physical (mechanical) bonding force between the carbon fiber and the resin. will be.

3 shows a state in which the graphitized carbon fiber and the resin (R) are chemically bonded. In this way, even in the case of graphite carbonized carbon, if the carbon fiber and the resin can be chemically bonded, the sliding at the interface between the carbon fiber and the resin is suppressed and reflects the characteristics of low thermal expansion coefficient and high strength of the carbon fiber itself. It is possible to obtain a composite material of carbon fiber and resin.

By using these composite materials as a core material constituting the wiring board, for example, the thermal expansion coefficient with the semiconductor element mounted on the wiring board can be matched with a low thermal expansion coefficient, and the wiring board is made high in strength. The deformation of the wiring board and the like can be prevented to improve the reliability of the wiring board, the semiconductor package, and the semiconductor device.

Below, as an example of a carbon raw material, the specific processing example which performs a modification process on the graphitized carbon fiber is shown.

(Strong alkali treatment)

The strong alkali treatment is a process which makes strong alkali act on the graphitized carbon fiber, and introduce | transduces a hydroxyl group as an active group on the surface of a carbon fiber.

For example, inorganic alkalis such as sodium hydroxide, potassium hydroxide ammonium hydroxide, or ammonium bicarbonate aqueous solution of 1 to 3 molar concentrations (mol / m 3) are used as an electrolyte, and carbon fibers or bundles of carbon fibers are immersed as an anode, 2 By processing for 10 minutes while applying a voltage of about volts, a hydroxyl group can be partially introduced into the surface of the graphitized carbon fiber.

As another method, sulfuric acid or nitric acid aqueous solution having a concentration of 1 to 3 mol (mol / m 3) is used as an electrolyte solution, and carbon fiber bundles in which carbon fibers or carbon fibers are bundled are immersed as an anode, and about 2 volts. By treating for 10 minutes while applying a voltage of, a hydroxyl group can be partially introduced into the surface of the graphitized carbon fiber.

When the resin is brought into contact with a carbon fiber having a hydroxyl group introduced on the surface thereof, the resin and the hydroxyl group are chemically bonded to each other to improve adhesion and bonding between the carbon fiber and the resin.

(Plasma treatment)

A method of setting a graphite carbon fiber or a bundle of carbon fibers in a chamber and performing plasma discharge under reduced pressure, introducing plasma or alcohol by introducing alcohol or aldehydes into the chamber, or performing plasma discharge using a chamber in a carbon dioxide atmosphere. will be. Plasma discharge is performed in the temperature range of about 200 degreeC from room temperature.

By this plasma treatment, a ketone group, an ether group, and a hydroxyl group can be partially introduced into the surface of the carbon fiber as an active group.

Therefore, by performing a plasma treatment on the carbon fibers, the carbon fibers and the resin can be chemically bonded, and the adhesion and bonding strength between the carbon fibers and the resin can be improved.

(Ion beam treatment)

By irradiating an atom such as nitrogen and oxygen at a room temperature under a reduced pressure using an ion accelerator (200 keV, 10 µA) to a graphitized carbon fiber or carbon fiber bundle at a fluence rate of 1014 / cm 2 to 1018 / cm 2 The surface of the carbon fiber is modified.

After the ion irradiation, the surface of the carbon fiber is partially formed of a graphite structure composed of only the original carbon atoms, and partially forms an ether group C-O-C, a carbonyl group C = O, a carbon C-O-, an amino group bonded to an oxygen radical, and the like. When carbon C-O.to which oxygen radicals bond is taken out into the atmosphere, it becomes hydroxyl group C-OH, and reacts with the precursor of the base resin similarly to the carbonyl group to form a chemical bond to form a structure highly reactive with the resin base material. The modified carbon fiber can obtain high adhesion by impregnating the resin and reacting chemically with the resin substrate precursor during thermal lamination when forming a printed substrate.

(Intercalation using strong alkali)

Lithium ions and potassium ions are infiltrated between the graphite layers at high temperature and high pressure (for example, 300 DEG C and 10 atm), heated to normal pressure, and partially peeled off to improve physical adhesion to the resin. In addition, a hydroxyl group C-OH is formed in part by a washing process after impregnating strong alkali ions, which obtains high adhesion by chemically bonding with a resin substrate precursor during thermal lamination when forming a printed substrate.

(Adhesion test)

A woven fabric (carbon fiber woven fabric) is produced using carbon fibers subjected to the above-described strong alkali treatment, plasma treatment, ion beam treatment, and intercalation treatment (mixed acid treatment), and the carbon fiber woven fabric is impregnated with a precursor of a resin substrate to carbon fibers. Prepreg was produced. This carbon fiber prepreg was laminated | stacked by press condition 1 MPa * 200 degreeC * 120 minutes, and the plate-shaped sample of thickness 1mm was produced.

As shown in FIG. 4, the adhesion test was performed by sandwiching the sample 5 with a jig 6 made of aluminum having a diameter of 10 mm, and measuring the peel strength. The plate-shaped sample 5 was bonded to the jig 6 through the adhesive resin 7.

The result of having performed the adhesion test (tension test) in FIG. 5 is shown graphically. In the graph, untreated is a result of testing a sample formed by impregnating a precursor of a resin substrate without performing any of the above-described strong alkali treatment or plasma treatment on carbon fibers. Comparing the adhesion strength between this untreated sample and the sample subjected to the above treatment, it can be seen that the peeling strength is greatly improved for the sample subjected to the above treatment.

As a result of observing the peeling state of the sample, the untreated sample had a fracture surface at the interface between the surface of the carbon fiber and the resin, and the treated sample was broken within the resin. It is considered that this is because the carbon fiber and the resin form a chemical bond by performing the above treatment on the carbon fiber, and the adhesion between the carbon fiber and the resin is improved.

This test result shows that the board | substrate formed using the carbon fiber which performed the said process has sufficient strength as a board | substrate used for a wiring board, and can use suitably for a wiring board.

(Use example of carbon fiber resin material)

Forming a woven fabric from the carbon fiber fibers subjected to the above-described treatment to improve the adhesion and bonding with the resin, or impregnating the carbon fiber fibers in parallel, for example, impregnating with epoxy resin and drying the B stage of semi-curing The prepreg is formed in a state. The prepreg can be used as a constituent material of the core portion of the wiring board by laminating a predetermined longevity in consideration of the coefficient of thermal expansion, strength, or the like, heating and pressing to form a flat body.

FIG. 6 shows an example of forming a wiring board having three prepregs 10a, 10b, 10c formed by impregnating a resin into a woven fabric of carbon fiber as a core part.

FIG. 6A shows a state in which the prepregs 12 including the prepregs 10a, 10b and 10c and the filler covering the surface of the core portion are arranged in alignment. In this state, the core part 10 containing carbon fiber is formed by pressurizing and heating the prepreg 10a, 10b, 10c and the prepreg 12 (FIG. 6B). The prepreg 10a, 10b, 10c is formed in advance by the process which improves adhesiveness with a resin base material in a carbon fiber, and the core part 10 exhibits the characteristic of low thermal expansion coefficient and high strength inherent in a carbon fiber.

FIG. 6C shows a lower hole 13 for penetrating through-holes through the core portion 10, and fills the lower hole 13 with an electrically insulating resin 14, and the resin 14 A through hole is formed on the inner wall surface of the through hole, the resin 17 is filled in the through hole, and a conductor layer is formed on the surface of the core part. The conductor layer on the surface) is patterned to form a wiring substrate 18a on the surface of the core portion 10 to form a core substrate. The conductor layer formed on the inner side surface of the through hole becomes the through hole 18b.

A wiring board can be obtained by forming a wiring layer on both surfaces of this core board by a buildup method or the like.

The wiring board thus obtained has sufficient properties such as low thermal expansion coefficient and high strength of the carbon fiber itself because the core portion 10 containing the carbon fiber improves the adhesion between the carbon fiber and the resin substrate. It is possible to improve the reliability of the semiconductor device obtained by mounting. In addition, since the core portion is formed with high strength, the wiring board can be thinned and provided as a product having a predetermined required strength. Moreover, since the thermal conductivity of a core part is favorable, it can provide as a semiconductor device excellent in heat dissipation.

In addition, the composite material made of the carbon material and the resin according to the present invention can be used in the core portion of a multilayer wiring board, but also for evaluation of general printed wiring boards, various types of semiconductor packages, sealing members of packages, and semiconductor wafers. It can use for various electronic devices, such as a board | substrate and a heat radiating board for electronic devices.

1 is an electron micrograph showing a cross-sectional structure of a prepreg impregnated with resin in a fiber made of carbon fiber.

2 is an electron micrograph showing the configuration of the carbon fiber.

3 is an explanatory diagram showing a state in which a carbon fiber and a resin are chemically bonded.

4 is an explanatory diagram illustrating a configuration of a jig used for an adhesion test.

5 is a graph showing the results of the adhesion test.

FIG. 6 is a cross-sectional view showing a step of forming a wiring board using a resin material containing carbon fibers at a core portion of the wiring board. FIG.

Claims (9)

A composite material made of carbon material and resin with graphite or graphite structure, A composite material comprising a carbon material and a resin, wherein the surface of the carbon material is modified, and the resin and the carbon material are chemically or physically bonded. The composite material comprising a carbon material and a resin according to claim 1, wherein the carbon atoms on the surface of the carbon material and the molecules of the resin are chemically bonded. The composite material comprising a carbon material and a resin according to claim 1, wherein the carbon material and the resin are bonded via an organic material or an inorganic material chemically bonded to carbon atoms on the surface of the carbon material. The composite material of claim 1, wherein the carbon material is a carbon fiber. A process of modifying the surface of the carbon material having a graphite or graphite structure to form an active group chemically bonded to the resin or a site physically bonded to the resin; And forming a composite material of the carbon material and the resin by contacting the resin with the carbon material subjected to the modification treatment. The method for producing a composite material of a carbon material and a resin according to claim 5, wherein a strong alkali treatment is performed as said modification treatment. The method for producing a composite material of a carbon material and a resin according to claim 5, wherein a plasma treatment is performed as the modification treatment. The method for producing a composite material of a carbon material and a resin according to claim 5, wherein a carbon fiber is used as the carbon material. An electronic device using a composite material consisting of a carbon material and a resin having a graphite or graphite structure, the surface of the carbon material is modified, and the carbon material and the resin formed by chemically or physically bonding the resin and the carbon material.

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