JP2009155628A - COMPOSITE MATERIAL COMPRISING CARBON MATERIAL AND RESIN AND PROCESS FOR PRODUCING THE SAME - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a composite material comprising a carbon material and resin that can fully give the original characteristics of the carbon material, and a suitable producing method. <P>SOLUTION: The composite material comprises the carbon material having graphite or a graphite structure, and resin. The surface of the carbon material is modified, and the resin and the carbon material are chemically or physically bonded. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

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

  As a wiring board on which a semiconductor element is mounted, there is a product containing a carbon fiber in a core portion of a core board. The wiring board using the core substrate containing carbon fiber in the core part has a low thermal expansion coefficient compared with the wiring board using the core substrate made of the conventional glass epoxy, and matches the thermal expansion coefficient with the semiconductor element. The thermal stress generated between the semiconductor element and the wiring board can be suppressed, and the wiring board is provided with high reliability.

The core part containing the carbon fiber of the core substrate is formed by superposing a plurality of prepregs formed by impregnating carbon fiber with a resin, and heating and pressing to integrate them. The core substrate is formed by laminating wiring layers on both surfaces of the core portion, and a wiring layer can be formed on both surfaces of the core substrate by a build-up method or the like.
JP 2003-273482 A Japanese Patent Laid-Open No. 11-269362

The core part containing the carbon fiber described above has a characteristic that it has a high thermal conductivity and a high strength in addition to having a low coefficient of thermal expansion compared to a glass epoxy substrate or the like. This characteristic of high thermal conductivity and high strength is useful as a characteristic of the core substrate constituting the wiring board.
Examples of the organic material having a low coefficient of thermal expansion and high strength include aramid fibers. However, since the aramid fiber has a low elastic modulus, if it is used in the core portion, it is dominated by the thermal expansion force of the resin base material and cannot exhibit the characteristic of low thermal expansion coefficient. On the other hand, since carbon fiber has a high elastic modulus, it can exhibit the original characteristics of low thermal expansion coefficient, and can also exhibit the original characteristics of strength and thermal conductivity. There is.

However, as in the case where the core portion is formed from a prepreg containing carbon fiber, the original properties of the carbon fiber are sufficiently exhibited in the resin material composed of the resin base material and the carbon fiber. Therefore, the adhesion between the carbon fiber and the resin base material becomes a problem.
The present invention provides a composite material composed of a carbon material and a resin that can exhibit the original characteristics of a carbon material such as carbon fiber, as in the case where a wiring substrate containing carbon fiber is formed in the core portion, and its preferred An object of the present invention is to provide a simple manufacturing method.

The present invention has the following configuration in order to achieve the above object.
That is, it is a composite material composed of graphite or a carbon material having a graphite structure and a resin, the surface of the carbon material is modified, and the resin and the carbon material are chemically or physically bonded. Features.
The reforming treatment is a method of, for example, applying a strong alkali treatment to the carbon material to form an active group on the surface of the carbon material in order to improve the chemical bond between the carbon material and the resin, or the carbon material. This is a method in which plasma treatment or ion beam treatment is performed to form irregularities on the surface of the carbon material, and the bondability between the carbon material and the resin is improved using an anchoring action.

As an aspect in which the carbon material and the resin are chemically bonded, a carbon atom on the surface of the carbon material and a molecule of the resin are chemically bonded, or the carbon material and the resin A resin in which the resin is bonded via an organic material or an inorganic material chemically bonded to the carbon atom on the surface of the carbon material is effectively used.
In addition, a composite material of a carbon material and a resin using a carbon fiber as a carbon material is particularly useful in that it has a low coefficient of thermal expansion and high strength.

In addition, as a method for producing a composite material of a carbon material and a resin, a modification that forms 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 a 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 reforming treatment, a method of subjecting the carbon material to strong alkali treatment and a method of subjecting the carbon material to plasma treatment can be used effectively.

  The composite material composed of the carbon material and the resin according to the present invention improves the bondability between the carbon material and the resin by applying a modification treatment to the carbon material, and suppresses slippage at the interface between the carbon material and the resin. In addition, it can be provided as a composite material having sufficient characteristics inherent to the carbon material.

FIG. 1 is an electron micrograph showing a cross-sectional structure of a prepreg formed by impregnating a carbon fiber with a resin. In FIG. 1, the fiber portion extending in the left-right direction shows a cross section parallel to the longitudinal direction of the carbon fiber, and the portion where small points are gathered shows a cross section perpendicular to the longitudinal direction of the carbon fiber. The part that appears black in the middle of the carbon fiber is the resin part. In addition, the fiber part of a figure is formed in bundle shape by putting many carbon fibers together. When forming a woven fabric from carbon fibers, a method of using a carbon fiber bundle in which a large number of carbon fibers are collected is generally used.
The prepreg shown in FIG. 1 is formed by forming a woven fabric from carbon fiber bundles and impregnating the woven fabric with resin, and the resin is filled in the middle of adjacent carbon fiber bundles.

FIG. 2 is an enlarged electron micrograph of a single fiber (carbon fiber bundle) made of carbon fibers. A carbon fiber obtained by baking resin resin at a high temperature of about 3000 ° C. and graphitizing is such that shallow grooves are formed on the outer surface of the fiber, and the outer surface of the fiber is extremely smooth. Therefore, when a prepreg is made by impregnating a woven fabric made of carbon fiber with a resin, even if the carbon fiber and the resin are in close contact with each other at first glance, the mechanical bond between the carbon fiber and the resin is weak. Is almost in close contact. In addition, the graphitized carbon fiber is chemically stable and does not chemically bond to the resin.
For this reason, for example, a plurality of prepregs formed by impregnating a carbon fiber with a resin, a core portion integrally formed by heating and pressing, is originally provided in the carbon fiber due to slippage between the carbon fiber and the resin. Excellent properties such as low coefficient of thermal expansion and high strength cannot be exhibited.

The method for producing a composite material comprising a carbon material and a resin according to the present invention is characterized by improving the chemical or physical bond between the carbon material and the resin by subjecting the carbon material to a modification treatment. As a result, the characteristics of the carbon material are reflected.
For example, in the case of graphitized carbon fiber as a carbon material, a modification treatment is applied to the carbon fiber to facilitate chemical bonding between the carbon fiber and the resin, or the physical (mechanical) between the carbon fiber and the resin. ) To improve the bond strength.

  FIG. 3 shows a state in which the graphitized carbon fiber and the resin R are chemically bonded. As described above, even if the carbon fiber is graphitized, if the carbon fiber and the resin can be chemically bonded, the slip at the interface between the carbon fiber and the resin is suppressed, and the low thermal expansion coefficient of the carbon fiber itself is provided. It is possible to obtain a composite material of carbon fiber and resin reflecting characteristics such as high strength.

  Then, by using these composite materials as, for example, a core material constituting the wiring board, the thermal expansion coefficient of the wiring board can be matched with a semiconductor element mounted on the wiring board with a low thermal expansion coefficient. By increasing the strength of the substrate, it is possible to prevent deformation such as warping of the wiring substrate, and to improve the reliability of the wiring substrate, semiconductor package, semiconductor device, and the like.

Hereinafter, as an example of the carbon material, a specific processing example in which the reforming process is performed on the graphitized carbon fiber will be described.
(Strong alkali treatment)
The strong alkali treatment is a treatment in which a strong alkali is allowed to act on the graphitized carbon fiber to introduce a hydroxyl group as an active group on the surface of the carbon fiber.
As an example, an inorganic alkali such as sodium hydroxide, potassium hydroxide ammonium carbonate or ammonium hydrogen carbonate aqueous solution of 1 to 3 mol concentration (mol / m ³ ) is used as an electrolyte, and a carbon fiber or carbon fiber is used as an anode. By dipping and treating for 10 minutes while applying a voltage of about 2 volts, hydroxyl groups can be partially introduced into the surface of the graphitized carbon fiber.

As another method, an aqueous solution of sulfuric acid or nitric acid having a concentration of 1 to 3 mol (mol / m ³ ) is used as an electrolyte, and carbon fiber or a bundle of carbon fibers in a bundle is immersed as an anode. By treating for 10 minutes while applying a voltage of about volts, hydroxyl groups can be partially introduced into the surface of the graphitized carbon fiber.
When the resin is brought into contact with the carbon fiber having a hydroxyl group introduced on the surface, the resin and the hydroxyl group are chemically bonded, and the adhesion and bonding property between the carbon fiber and the resin can be improved.

(Plasma treatment)
A method in which graphitized carbon fiber or carbon fiber bundle is set in a chamber and plasma discharge is performed under reduced pressure, a method in which alcohol or aldehyde is introduced into the chamber and plasma discharge is performed, and plasma discharge is performed in a carbon dioxide atmosphere in the chamber. It is by the method to do. Plasma discharge is performed in a temperature range from room temperature to about 200 ° C.
By this plasma treatment, a ketone group, an ether group, or a hydroxyl group can be partially introduced as an active group on the surface of the carbon fiber.
Therefore, by applying plasma treatment to the carbon fiber, the carbon fiber and the resin can be chemically bonded, and the adhesion and bonding force between the carbon fiber and the resin can be improved.

(Ion beam processing)
Using ion acceleration apparatus (200 keV, 10 .mu.A), under vacuum, at room temperature, nitrogen, atoms such as oxygen, as fluence rate ^{1014 / cm 2 ~1018 / cm 2} , the carbon fibers or carbon fiber bundles were graphitized The surface of the carbon fiber is modified by irradiating the surface.
After the ion irradiation, the surface of the carbon fiber is partially composed of the graphite structure consisting only of the original carbon atoms, partially with ether group COC, carbonyl group C = O, carbon CO with oxygen radicals bonded, amino group, etc. Formed. Carbon CO, combined with oxygen radicals, becomes hydroxyl C-OH when taken out into the atmosphere, and reacts with the resin base material, reacting with the precursor of the base resin, like the carbonyl group. A highly structured structure is formed. The modified carbon fiber can be impregnated with a resin to react with the resin base material precursor during the heat lamination when forming the printed circuit board and chemically bond to obtain high adhesion.

(Intercalation using strong alkali)
Improve physical adhesion with the resin by allowing lithium ions and potassium ions to penetrate between the graphite layers at high temperature and high pressure (for example, 300 ° C, 10 atm), heating at normal pressure, and partially delaminating. . In addition, hydroxyl group C-OH is partially formed in the cleaning process after impregnation with strong alkali ions, which is chemically reacted with the resin base precursor during heating lamination when forming a printed circuit board. High adhesion is obtained by bonding.

(Adhesion test)
Fabricate a woven fabric (carbon fiber woven fabric) using the carbon fiber that has been subjected to the above-mentioned strong alkali treatment, plasma treatment, ion beam treatment, and intercalation treatment (mixed acid treatment). A carbon fiber prepreg was prepared by impregnating the precursor. This carbon fiber prepreg was laminated under a press condition of 1 MPa / 200 ° C./120 minutes to prepare a plate-like sample having a thickness of 1 mm.
As shown in FIG. 4, the adhesion test was performed by sandwiching a sample 5 with an aluminum jig 6 having a diameter of 10 mm and measuring the peel strength. The plate-like sample 5 was joined to the jig 6 via the adhesive resin 7.

  FIG. 5 is a graph showing the results of the adhesion test (tensile test). In the graph, “no treatment” means the result of testing a sample formed by impregnating a precursor of a resin base material without subjecting the carbon fiber to the above-described strong alkali treatment or plasma treatment at all. Comparing the adhesion strength between the untreated sample and the treated sample, it can be seen that the peel strength is greatly improved for the treated sample.

When the peeled state of the sample was observed, the fracture surface of the untreated sample was generated at the interface between the surface of the carbon fiber and the resin, and the treated sample was broken inside the resin. This is considered to be due to the result that the carbon fiber and the resin form a chemical bond and the adhesion between the carbon fiber and the resin is improved by applying the above treatment to the carbon fiber.
This experimental result shows that the substrate formed using the carbon fiber subjected to the above treatment has sufficient strength as a substrate used for the wiring substrate and can be suitably used for the wiring substrate.

(Application example of carbon fiber resin material)
Form a woven fabric from carbon fiber fibers that have been treated to improve the adhesion and bonding properties with the resin described above, or impregnate, for example, epoxy resin in a state where the carbon fiber fibers are aligned in parallel, and then dried. Thus, a prepreg is formed as a semi-cured B-stage state. A predetermined number of the prepregs are laminated in consideration of the coefficient of thermal expansion or strength, and heated and pressed to form a flat plate, which can be used as a constituent material for the core portion of the wiring board.

FIG. 6 shows an example of forming a wiring board having three prepregs 10a, 10b, and 10c formed by impregnating a carbon fiber woven fabric with resin.
FIG. 6A shows a state in which the prepregs 10a, 10b, and 10c and the filler-containing prepreg 12 that covers the surface of the core portion are aligned and arranged. In this state, the core part 10 containing carbon fiber is formed by pressurizing and heating the prepregs 10a, 10b, 10c and the prepreg 12 (FIG. 6B). The core portion 10 exhibits characteristics such as the low thermal expansion coefficient and high strength inherent to the carbon fiber by forming the prepregs 10a, 10b, and 10c in advance by subjecting the carbon fiber to a treatment for improving the adhesion to the resin base material. It becomes.

FIG. 6C shows a case where a lower hole 13 is formed in the core portion 10 for penetrating a conductive through hole, an electrically insulating resin 14 is filled in the lower hole 13, and a through hole is formed in the resin 14. A step of forming a conductor layer on the inner wall surface of the through hole, filling the through hole with resin 17 and forming a conductor layer on the surface of the core portion 10, and then patterning the conductor layer on the surface of the core portion 10 10 shows a state in which a wiring pattern 18a is formed on the surface of 10 and a core substrate is formed. The conductor layer formed on the inner surface of the through hole becomes the conduction through hole 18b.
A wiring board is obtained by forming a wiring layer on both surfaces of the core board by a build-up method or the like.

  The wiring board thus obtained has the core part 10 containing carbon fiber sufficiently provided with the characteristics of low thermal expansion coefficient and high strength of the carbon fiber itself due to improved adhesion between the carbon fiber and the resin base material. Thus, the reliability of the semiconductor device obtained by mounting the semiconductor element on the wiring board can be improved. In addition, since the core portion is formed with high strength, the wiring board can be thinned and provided as a product having a required strength. In addition, since the core portion has good thermal conductivity, it can be provided as a semiconductor device with excellent heat dissipation.

  The composite material composed of the carbon material and the resin according to the present invention can be used for the core portion of the multilayer wiring board, as well as a general printed wiring board, various forms of semiconductor packages, package sealing members, and semiconductor wafers. It can utilize for various electronic devices, such as a board | substrate for evaluation of this, and a thermal radiation board | substrate for electronic devices.

3 is an electron micrograph showing a cross-sectional structure of a prepreg obtained by impregnating a fiber made of carbon fiber with a resin. It is an electron micrograph which shows the structure of a carbon fiber. It is explanatory drawing which shows the state which a carbon fiber and resin chemically bond. It is explanatory drawing which shows the structure of the jig | tool used for an adhesive force test. It is a graph which shows the result of an adhesion test. It is sectional drawing which shows the process of forming a wiring board using the resin material containing a carbon fiber for the core part of a wiring board.

Explanation of symbols

10 core part 10a, 10b, 10c prepreg 18a wiring pattern 18b conduction through hole

Claims (9)

A composite material composed of graphite or a carbon material having a graphite structure and a resin,
A composite material comprising a carbon material and a resin, wherein a surface of the carbon material is modified and the resin and the carbon material are chemically or physically bonded.   2. The composite material comprising a carbon material and a resin according to claim 1, wherein carbon atoms on the surface of the carbon material are chemically bonded to molecules of the resin.   The carbon material and the 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 a carbon atom on the surface of the carbon material. A composite material consisting of   The said carbon material is a carbon fiber, The composite material which consists of a carbon material and resin as described in any one of Claims 1-3 characterized by the above-mentioned. A step of modifying the surface of graphite or a carbon material having a graphite structure to form an active group chemically bonded to the resin or a site physically bonded to the resin;
A method of producing a composite material of a carbon material and a resin, comprising: bringing the resin into contact with the carbon material subjected to the modification treatment to form a composite material of the carbon material and the resin. .   6. 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 the modification treatment.   6. 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.   Carbon fiber is used as said carbon material, The manufacturing method of the composite material of the carbon material and resin as described in any one of Claims 5-7 characterized by the above-mentioned.   Composed of graphite or a carbon material having a graphite structure and a resin, the surface of the carbon material is modified, and the resin and the carbon material are chemically or physically combined to form a carbon material and a resin. Electronic devices using composite materials.