JP2001064359A - Epoxy resin composition and wiring board using the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain an epoxy resin composition which is suited in forming insulating films capable of exhibiting excellent crack resistance, high flexibility, and excellent reliability at the time of bending the substrate or mounting parts on the substrate in the film formation of insulating films on the substrate formed from organic materials. SOLUTION: The epoxy resin composition is constituted by comprising (1) an epoxy resin component selected from the group consisting of an aromatic epoxy resin having an aromatic ring in the molecule, an alicyclic epoxy resin having a cyclohexane skeleton in the molecule, and a mixture thereof and (2) an epoxy curing agent having two or more hydroxyl groups and two or more aromatic rings in the molecule.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an epoxy resin composition, and more particularly to an epoxy resin composition which can be advantageously used for forming an insulating film in a semiconductor device or the like. The present invention also relates to a wiring board provided with an insulating film derived from such an epoxy resin composition. The wiring board of the present invention includes a multilayer circuit board such as an MCM-L / D board and a single-chip package board.

[0002]

2. Description of the Related Art Conventionally, printed circuit boards have been generally used for compactly incorporating electronic components into electronic equipment. Printed circuit boards are generally manufactured by etching a copper foil bonded to a laminate in accordance with a desired electronic circuit pattern. Therefore, it is difficult to mount electronic components at a high density. Therefore, it is widely used in the field of manufacturing electronic devices and the like.

On the other hand, a wiring board having a build-up multilayer wiring structure has been used for a long time to manufacture a hybrid integrated circuit (IC) or the like. This wiring board can be manufactured by sequentially printing and stacking a thick paste of a conductor and a thick paste of an insulator on a ceramic substrate and firing the paste. In recent years, miniaturization of electronic devices,
With the demand for higher performance and lower cost, miniaturization and multi-layering of electronic circuits on printed circuit boards and high-density mounting of electronic components are progressing, and therefore, build-up multilayer wiring for printed circuit boards. Examination of the structure is active. In a printed circuit board having a build-up multilayer wiring structure, it is necessary to form a build-up insulating film (so-called interlayer insulating film) between electronic circuit layers. The insulating film for build-up is on the entire surface of the lower electronic circuit, except that
It is formed except for a portion that is connected to an upper electronic circuit (a portion generally called a “via hole”).

Generally speaking, a printed wiring board having a conventional build-up multilayer wiring structure is manufactured according to the following procedure. First, a double-sided wiring board having a wiring pattern and a filled through hole is prepared as a core substrate. Next, a photosensitive resin is entirely applied to both surfaces of the core substrate, and exposure and development are performed to form an insulating film having via holes. Next, a conductor plating layer is entirely formed on the surface of the insulating film formed on both surfaces of the core substrate by using a common plating method such as electroless plating and electrolytic plating. Subsequently, the conductor plating layer is etched according to a desired wiring pattern. As a result, a core substrate provided with the conductor wiring is completed.

Thereafter, a series of steps from the formation of the insulating film to the formation of the conductor wiring described above are repeated as necessary. A printed wiring board having a desired multilayer wiring structure is obtained. In producing the printed wiring board as described above, various photosensitive resins (photoresists) are used as an insulating film forming material. The photosensitive resin can be cured through light irradiation, and if necessary, by irradiating light in a pattern, the insulating film can be patterned corresponding to the pattern. is there. Recently, from the viewpoint of decontamination,
For example, a photosensitive resin composition developable with a dilute aqueous solution of alkali such as sodium hydroxide has been used as an insulating film forming material. Examples of the alkali-developable photosensitive resin composition include, for example, a photosensitive resin having a reaction product obtained by reacting an unsaturated monocarboxylic acid with an epoxy resin and further adding a polybasic anhydride thereto. Composition (for example, JP-B-56-40)
No. 329 and JP-B-57-45785) and photosensitive compositions using a novolak-type epoxy resin as a base polymer (for example, JP-A-61-243).
869).

In manufacturing a printed wiring board having a conventional multilayer wiring structure, as described above, a photosensitive resin composition containing an epoxy resin as a base polymer is used as a material for forming an insulating film. However, most of the epoxy resins used here have no flexibility in rearrangement, in other words, epoxy resins having a poor flexibility or flexibility, for example, a bisphenol A type structure. Examples of the epoxy curing agent used in combination for curing the epoxy resin include compounds having no degree of freedom in rearrangement of atoms, such as acid anhydride, and intramolecular compounds, such as phenol-novolak resin. Are used because they have a large number of hydroxyl groups and therefore can produce a cured product having a very high crosslinking density. For this reason, in the production of a conventional printed wiring board, the above-described photosensitive resin composition is used to form a multilayer wiring on a substrate formed mainly of an organic material such as a resin and having excellent flexibility and flexibility. When fabricating a structure, there is a problem that cracks occur in the insulating film when the substrate is bent due to the necessity of handling or when components such as a BGA (ball grid array) are mounted on the substrate.

Various attempts have been made to solve the above-mentioned problems of the photosensitive resin composition using an epoxy resin as a material for forming an insulating film, particularly to solve the problem of brittleness of the insulating film. I have. For example, it has been proposed to add a rubber compound having a functional group at the terminal of a molecule to an epoxy resin (for example, the 29th National
Sampe Symposium Lectures, p. 422, 1984). However, when a rubber compound is added, although brittleness can be improved, a decrease in the elastic modulus of the resin must be accepted, and further improvement is required. Polymer, Vol. 30, pp. 213, 198
It has also been proposed to add a polyetherimide to an epoxy resin, as disclosed in 1999. However, in the case of polyetherimide, the compatibility with the epoxy resin is poor, so that there is a problem that phase separation and solubility deteriorate.

[0008]

SUMMARY OF THE INVENTION An object of the present invention is to provide an epoxy resin composition suitable for forming an insulating film, which solves the above-mentioned problems of the prior art and has a high tensile elongation. When forming an insulating film on a substrate formed of a flexible organic material, it exhibits excellent crack resistance, high flexibility and excellent reliability when bending the substrate or mounting components on the substrate. To provide an epoxy resin composition that can be used.

Another object of the present invention is to provide a wiring board using such an epoxy resin composition. These and other objects of the present invention will be readily understood from the following detailed description.

[0010]

Means for Solving the Problems The inventors of the present invention have conducted intensive studies to achieve the above-mentioned object, and as a result, have found that the crosslinking density of an epoxy cured product can be reduced and the molecular structure capable of being rearranged in the structure of an epoxy cured product. It was discovered that the goal could be achieved through the introduction of. In one aspect, the present invention provides: (1) an aromatic epoxy resin having an aromatic ring in the molecule, an alicyclic epoxy resin having a cyclohexane skeleton in the molecule, and a mixture thereof. Epoxy resin component, and (2) two or more hydroxyl groups and 2
An epoxy resin composition comprising: an epoxy curing agent having at least one aromatic ring.

[0011] The present invention also provides, in another aspect, a wiring board comprising an insulating film formed from the epoxy resin composition of the present invention. According to a preferred embodiment, the wiring board of the present invention has a form of a multilayer circuit board, and the insulating film is an interlayer insulating film.

[0012]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described below with reference to typical embodiments. It should be understood that the present invention is not limited to the embodiments described below. The epoxy resin composition according to the present invention is preferably used as a material for forming an insulating film, and needs to have at least the following two components.

(1) An epoxy resin component selected from the group consisting of an aromatic epoxy resin having an aromatic ring in the molecule, an alicyclic epoxy resin having a cyclohexane skeleton in the molecule, and a mixture thereof. (2) An epoxy curing agent having two or more hydroxyl groups and two or more aromatic rings in the molecule.

The aromatic epoxy resin which can be advantageously used as the epoxy resin component is not limited to those listed below, but is a bisphenol A type epoxy resin such as a tetrabromobisphenol A type epoxy resin. And other epoxy resins such as bisphenol F epoxy resin, bisphenol S epoxy resin, phenol-novolak epoxy resin, cresol-cynovolak epoxy resin, and brominated epoxy resins thereof.

The alicyclic epoxy resin which can be advantageously used alone or in combination with the above-mentioned aromatic epoxy resin is not particularly limited as long as it has a cyclohexane skeleton in its molecule. Alicyclic bifunctional epoxy resin, alicyclic 3
It is a functional epoxy resin, an alicyclic tetrafunctional epoxy resin or a mixture thereof.

The epoxy curing agent used in combination with the epoxy resin component is not particularly limited as long as it has two or more hydroxyl groups and two or more aromatic rings in the molecule. Can be arbitrarily selected and used. As the aromatic ring, a benzene ring is particularly preferable. Among such epoxy curing agents, particularly, a bonding group having two or more carbon atoms as a bonding group between two adjacent benzene rings contained in the molecule, for example, a hydrocarbon Epoxy curing agents containing a group (preferably a methylene group or the like) are preferred. Examples of suitable epoxy curing agents include 3,
A 3'-diethylenedioxydiphenol compound can be mentioned. Also, such epoxy curing agents may be used as a mixture containing a phenol-novolak resin as an additional component.

The epoxy curing agent can be added to the resin composition in various amounts depending on the type and amount of the epoxy resin component used, the desired effect, and the like. It is preferable that the compounding is performed such that a mixing ratio of about 0.8 to 1.1 equivalents as active hydrogen equivalent of the epoxy curing agent is obtained with respect to 1 equivalent of the epoxy group contained. In particular, the physical properties of the obtained epoxy cured product are improved.

The epoxy resin composition of the present invention may further have an optional additive, if necessary, in addition to the above two essential components. Suitable additives for the practice of the present invention are, for example, epoxy curing accelerators. Suitable epoxy curing reaction accelerators include, for example, imidazole compounds, triphenylphosphine, tertiary amines, and the like. Such a curing reaction accelerator is generally used in an amount of 1 to 100 parts by weight of the epoxy resin component.
It is preferable to add in the range of 10 parts by weight.

Further, an inorganic filler can be advantageously added to the epoxy resin composition of the present invention for the purpose of strengthening the insulating film. Suitable inorganic fillers include silica powder and the like. The inorganic filler is usually 10 to 30% by weight based on the total amount of the resin composition (excluding the solvent).
And more preferably 10
-20% by weight.

Further, examples of other additives that can be advantageously added to the epoxy resin composition of the present invention include a flame retardant (for example, antimony trioxide) and a leveling agent. . Although the epoxy resin composition of the present invention can be used in any form, it can generally be advantageously used as a varnish-like composition in consideration of applicability and handleability. The varnish-like epoxy resin composition can be prepared by dissolving the above components in a suitable solvent. Suitable solvents include, but are not limited to, those listed below, and organic solvents such as propylene glycol monoethers, acetates, cyclohexane, dioxane, xylene, and the like. These solvents may be used alone or as a mixture of two or more.

When the epoxy resin composition of the present invention is used, not only are various properties such as mechanical properties, electrical properties, and dimensional stability excellent, but also an organic material having high tensile elongation and flexibility is used. When used to form an insulating film in combination with a substrate, no defects such as cracks occur,
An insulating film having excellent flexibility and reliability can be formed. The formation of the insulating film from the epoxy resin composition of the present invention is not particularly limited to a forming method, and as will be understood from the following description, can be carried out using a common technique.

Further, when the epoxy resin composition of the present invention is used, it is possible to provide a wiring board having an excellent insulating film as described above. Here, the insulating film of the present invention can be advantageously used at any position of various wiring boards, and can be particularly advantageously used as an interlayer insulating film. FIG. 1 is a cross-sectional view schematically showing a printed wiring board having a build-up multilayer wiring structure, which is a preferred use example of such an interlayer insulating film. Of course, in practicing the present invention, satisfactory results can be obtained with a multilayer circuit board other than those shown.

In FIG. 1, a printed wiring board 10 includes
Electronic circuit layers 12 and 1 having a multilayer structure on both surfaces of laminated substrate 1
The electronic circuit layers 12 and 13 have a configuration in which the epoxy resin-based insulating film 2 and the conductor wiring (for example, copper) 3 according to the present invention are alternately stacked. . Further, through holes 5 filled with an insulating resin material 4 are formed in the laminated substrate 1 to connect the lower electronic circuit 12 and the upper electronic circuit 13. As understood from the drawing, in such a printed wiring board, it is necessary to form an insulating film for build-up (so-called interlayer insulating film) between layers of the electronic circuit. The build-up insulating film is formed on the entire surface of the lower electronic circuit except for a portion (generally referred to as a “via hole”) for connection with the upper electronic circuit.

Generally speaking, a printed wiring board having a build-up multilayer wiring structure as shown in FIG. 1 can be manufactured, for example, according to a manufacturing process shown in FIG. In the description of the printed wiring board in FIG. 2, a layer configuration slightly different from that in FIG. 1 is employed for easy understanding. (1) Fabrication of a core substrate A through hole 5 is formed in a selected substrate, and a wiring pattern 3 is formed on both surfaces of the substrate and the inner wall of the through hole.
Further, by filling the inside of the through hole with the insulating resin 4, the wiring 3 is formed on both sides as shown in FIG.
Is formed. This laminated substrate 1 is usually called a core substrate.

(2) Formation of Insulating Film Both surfaces of the laminated substrate 1 are coated with the epoxy resin composition of the present invention so as to cover the entire surface. Here, a varnish-like epoxy resin composition is prepared and coated by screen printing. In addition, as a coating method, in addition to a screen printing method, a curtain coating method, a roll coating method, a spin coating method, or the like can be used. The coating thickness of the epoxy resin composition can be varied widely depending on the desired result and the like, but is usually preferably in the range of about 40 to 60 μm. Next, the formed coating is heated at an appropriate temperature (for example, 120 ° C.) to dry the coating. After the drying of the film is completed, the epoxy resin component is further cured by heating at a temperature of, for example, about 170 to 200 ° C. Thereafter, a portion to be connected to an upper-layer electronic circuit to be subsequently formed, a so-called via hole portion (for example, a width of about 50 to 150 μm) is formed by mechanical processing. As processing equipment for forming via holes,
For example, a laser beam machine using a carbon dioxide laser, an excimer laser, a YAG laser, or the like can be advantageously used. As a result of forming a via in this way, FIG.
As shown in FIG. 7, the insulating film 2 having the via hole 6 is formed.

(3) Conductor Plating A conductor as a wiring precursor is entirely coated on the insulating film 2 formed in the previous step. This conductor coating step can be performed using a common plating method such as electroless plating and electrolytic plating. Prior to this plating step, it is preferable that the entire laminated substrate 1 is immersed in an alkaline solution such as an aqueous solution of permanganic acid, for example, to provide appropriate fine irregularities on the surface of the insulating film 2. This is because deposition of plating is further promoted. As shown in FIG. 2C, a conductor plating layer 7 is entirely formed on the surface of the insulating film 2 formed on both surfaces of the laminated substrate 1.

(4) Formation of Wiring The conductive plating layer 7 is etched according to a desired wiring pattern. This patterning step can be performed according to a conventional etching method. As a result, FIG.
As shown in (D), the laminated substrate 1 including the conductor wiring 3 is completed. Thereafter, although not shown, by repeating a series of steps from the formation of the insulating film to the formation of the conductor wiring described above, the printed wiring having the multilayer wiring structure as described above with reference to FIG. The substrate can be completed.

[0028]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will now be described with reference to embodiments. Example 1 The following components were mixed in the amounts described to prepare a coating solution of an epoxy resin composition.

Tetrabromobisphenol A type epoxy resin 75 parts by weight (trade name “Epiclon 153” manufactured by Dainippon Ink) 25 parts by weight of alicyclic epoxy resin having a cyclohexane skeleton (trade name “Araldite CY179” manufactured by Ciba Geigy) Phenol -Novolak resin 32 parts by weight (manufactured by Gun Ei Chemical Co., trade name "PSM-4300") 9.3 parts by weight of 3,3'-ethylenedioxydiphenol 1 part by weight of 2-methyl-4-ethylimidazole 6 parts by weight of silica powder Part Antimony trioxide 8 parts by weight Propylene glycol monomethyl ether acetate 18 parts by weight Cyclohexane 29 parts by weight [Measurement of peel strength] The coating solution prepared as described above was coated on a previously prepared copper foil substrate to a film thickness of 40 nm. Spin coat at 120 ° C for 20 minutes After heating at 170 ° C. for 60 minutes, the mixture was allowed to cool to room temperature.

After forming the insulating film as described above, the entire copper foil substrate was sequentially immersed in the following treatment bath. (1) Pretreatment agent (Shipley conditioner, 60
(C), 10 minutes) (2) Oxidizing agent (Shipley promoter, 70 ° C, 10 minutes)
Min, pH = 11) (3) Neutralizer (Shipley Nutriser, 60 ° C,
After a series of processing steps was completed, electroless copper plating and electrolytic copper plating were performed to form a 25 μm-thick conductor layer on the insulating film. When the peel strength of this conductor layer was measured by a peeling tester, it was confirmed to be 1.1 kgf / cm. [Measurement of tensile elongation] The coating solution prepared as described above was spin-coated on a previously prepared aluminum thin plate at a film thickness of 40 nm, then heated at 120 ° C for 20 minutes, and further heated at 170 ° C. And then allowed to cool to room temperature. The cured film was peeled off to obtain an epoxy cured film having a thickness of 40 μm, which was subjected to a tensile tester to measure elongation (tensile elongation). The tensile elongation of the epoxy cured film was found to be greater than 7.5%. [Repeated load test] Using the coating solution prepared as described above, a built-up multilayer wiring printed circuit board (core board + four-layer built-in) according to the built-up manufacturing method described above with reference to FIGS. Up + 2 layers on both sides) 1
0, and further, as shown in FIG.
A package 11 was mounted. When the obtained device was repeatedly subjected to a load test, it was confirmed that the device was bent by 3 mm and cleared the 750 breaking cycle. [USPCBT test] The coating solution prepared as described above was spin-coated at a film thickness of 40 nm on a BT (bismaleimide triazine) substrate having wiring of 126 μm, heated at 120 ° C. for 20 minutes, and
After heating at 70 ° C. for 60 minutes, it was allowed to cool to room temperature.

After the insulating film is formed on the wiring as described above, the temperature is 120 ° C., 85% RH (relative humidity), 1.7 atm.
, 24 V, 96 hours, an unsaturated pressure cooker test (USPCBT test) was performed. Between the measured wiring resistance of the order of 1 × 10 ⁷ Ω, it was confirmed that the order of the inter-wiring resistance 1 × 10 ⁷ Ω after the test is maintained. Therefore, the result of this test was determined to be “Pass”. [Other tests] Other tests were carried out using the coating solution prepared as described above, and the results as summarized in Table 1 below were obtained. That is,
When the epoxy cured film is gradually heated, the temperature at which the weight starts to decrease (the temperature at which the weight starts to decrease) is 278 ° C., the glass transition temperature (Tg) is 115 ° C., and the relative dielectric constant is 3. 8, the water absorption was 0.6%, and the breaking strength was 75 to 80 MPa. Example 2 The following components were mixed in the amounts described to prepare a coating solution of an epoxy resin composition.

75 parts by weight of a tetrabromobisphenol A type epoxy resin (trade name “Epiclon 153” manufactured by Dainippon Ink) 25 parts by weight of an alicyclic epoxy resin having a cyclohexane skeleton (trade name “Araldite CY179” manufactured by Ciba Geigy) Phenol -Novolak resin 32 parts by weight (trade name "PSM-4300" manufactured by Gunei Chemical Co., Ltd.) 4.7 parts by weight of 3,3'-ethylenedioxydiphenol 1 part by weight of 2-methyl-4-ethylimidazole 1 part by weight of silica powder 6 parts by weight Part Antimony trioxide 8 parts by weight Propylene glycol monomethyl ether acetate 18 parts by weight Cyclohexane 29 parts by weight The coating solution prepared as described above was formed into a film according to the method described in Example 1 above, and the obtained epoxy cured film was evaluated. When subjected to the test, the results are as shown in Table 1 below. Results were obtained. In addition, in the repeated load test, it was confirmed that the 750 rupture cycle was cleared by bending by 3 mm. In the USPCBT test, the resistance between wirings was 1 × 10 ⁷ Ω.
And the wiring resistance after the test is also 1 × 10 ⁷ Ω
It was confirmed that the order was maintained. Comparative Example 1 The following components were mixed in the stated amounts to prepare a coating solution of the epoxy resin composition.

75 parts by weight of tetrabromobisphenol A type epoxy resin (trade name “Epiclon 153” manufactured by Dainippon Ink) 25 parts by weight of alicyclic epoxy resin having a cyclohexane skeleton (trade name “Araldite CY179” manufactured by Ciba Geigy) Phenol -Novolak resin 40 parts by weight (trade name "PSM-4300", manufactured by Gun Ei Chemical Co., Ltd.) 2-Methyl-4-ethylimidazole 1 part by weight Silica powder 6 parts by weight Antimony trioxide 8 parts by weight Propylene glycol monomethyl ether acetate 18 parts by weight 29 parts by weight of cyclohexane The coating solution prepared as described above was formed into a film according to the method described in Example 1, and the obtained epoxy cured film was subjected to an evaluation test. Results were obtained. In addition, in the repeated load test, it was confirmed that only 80 rupture cycles were obtained after bending by 3 mm. In the USPCBT test, the resistance between wirings was 1 × 10 ⁷ Ω.
And the wiring resistance after the test is also 1 × 10 ⁷ Ω
It was confirmed that the order was maintained.

[0034]

[Table 1]

As can be understood from the test results shown in Table 1 above, according to the present invention, it is possible to obtain an insulating material exhibiting particularly higher flexibility and elongation than conventional epoxy resin compositions. Can be.

[0036]

As described above, according to the present invention, there is provided an epoxy resin composition suitable for forming an insulating film, comprising a substrate formed of an organic material having high tensile elongation and flexibility. It is possible to provide an epoxy resin composition capable of exhibiting excellent crack resistance, high flexibility, and excellent reliability when a substrate is bent or a component is mounted on the substrate when an insulating film is formed thereon. it can. In fact, the use of the epoxy resin composition of the present invention can provide an insulating material exhibiting higher flexibility and elongation as compared with a composition using a conventional phenol-novolak resin as an epoxy curing agent. . Further, according to the present invention, a printed wiring board having a high-performance insulating film can be provided by using such an epoxy resin composition as an insulating film forming material. Specifically, it is possible to realize a built-up board that does not crack when components such as BGA are mounted.

[Brief description of the drawings]

FIG. 1 is a schematic sectional view showing an example of a printed wiring board having a multilayer wiring structure according to the present invention.

FIG. 2 is a cross-sectional view sequentially showing a manufacturing process based on a built-up manufacturing method of the printed wiring board of FIG. 1;

FIG. 3 shows B for the built-up multilayer wiring printed circuit board of FIG. 1;
FIG. 3 is a schematic cross-sectional view showing a state where a GA package is mounted.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 ... Laminated board 2 ... Insulating film 3 ... Conductor wiring 4 ... Resin material 5 ... Through hole 6 ... Via hole 7 ... Conductor plating layer 10 ... Printed wiring board 11 ... BGA package 12 ... Electronic circuit layer 13 ... Electronic circuit layer

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI Theme coat ゛ (Reference) H05K 3/46 H05K 3/46 BF term (Reference) 4J036 AD08 AD09 AD21 AF06 AF10 AJ08 DB06 DC41 JA08 4J038 DA042 DB041 DB061 DB071 DB261 GA06 JA64 KA03 NA21 PB09 5E314 AA32 BB06 CC07 FF01 FF08 GG03 GG09 5E346 CC32 DD12 DD25 EE33 FF13 FF14 GG22 HH08 HH11

Claims (2)

[Claims] 1. The following components: (1) an epoxy resin selected from the group consisting of an aromatic epoxy resin having an aromatic ring in the molecule, an alicyclic epoxy resin having a cyclohexane skeleton in the molecule, and a mixture thereof; Component, and (2) two or more hydroxyl groups and 2
An epoxy resin composition comprising: an epoxy curing agent having at least one aromatic ring. 2. A wiring board comprising an insulating film formed from the epoxy resin composition according to claim 1.