JP2000273275A - Insulating resin composition and circuit board containing insulation film formed thereof - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain the subject composition containing no impurities including halogens, causing no insulation drop of the insulation films therefrom, and useful for insulation films for build-up circuit boards by including an alicyclic epoxy resin, an epoxy curing agent, and a polybutadiene compound, etc. SOLUTION: This composition is obtained by including (A) an alicyclic epoxy resin, (B) an epoxy curing agent intended for the resin A, (C) a polybutadiene compound, silica powder, or a monomer or precursor capable of forming a polyimide or polyetherimide when heated; wherein the component A which is an epoxy resin having a cyclohexane skeleton, is pref. a bifunctional epoxy resin, trifunctional epoxy resin, tetrafunctional epoxy resin, or a mixture of two or more thereof; and the component B is pref. a phenol novolak resin or acid anhydride, or a mixture of a silanol-contg. compound and a metal-contg. compound.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to the field of multilayer circuit boards including a multichip module type board (MCM-L / D board) and a signal chip package board manufactured by a laminate and deposition method. Specifically, the present invention relates to an insulating resin composition used for manufacturing such a multilayer circuit board, and a multilayer circuit board including an insulating film formed by the resin composition. This resin composition is effective for forming a wiring by plating, and is particularly useful as an insulating film for a build-up circuit board.

[0002]

2. Description of the Related Art Conventionally, printed circuit boards have been generally used for compactly incorporating electronic components into electronic equipment. This printed board is manufactured by etching a copper foil bonded to a laminate according to an electronic circuit pattern, and it is difficult to mount electronic components at high density, but it is advantageous in terms of cost. Hybrid I
As a circuit board for C, a board having a build-up multilayer wiring structure has been used for a long time. This build-up multilayer wiring circuit board is manufactured by sequentially printing and stacking a thick film paste of a conductor and an insulator on a ceramic substrate, followed by firing.

On the other hand, along with demands for downsizing, high performance, and low cost of electronic devices, in recent years, electronic circuits on printed circuit boards have been miniaturized, multilayered, and electronic components have been mounted at a high density. Also, studies on build-up multilayer wiring structures for printed circuit boards have been activated.

In a build-up multilayer wiring circuit board, a build-up insulating film is formed between electronic circuit layers. This insulating film is formed as a film on the entire surface of the substrate except for a portion where the upper and lower electronic circuits are to be connected (a portion generally called a “via hole”).

An example of a conventional process for manufacturing a multilayer circuit board having a build-up structure will be specifically described. First, a double-sided wiring board having a wiring pattern and through holes filled with insulating resin is prepared as a core substrate. Next, a photosensitive resin is applied to both sides of the core substrate, and is exposed and developed to form an insulating film having a predetermined pattern of via holes. Next, a conductor layer is formed on the insulating film by electroless plating and electrolytic plating, and this is etched to form a wiring pattern. Thereafter, if necessary, the steps from the formation of the insulating film to the formation of the wiring pattern are repeated to produce a multilayer wiring structure.

As a photosensitive resin for forming an insulating film, a photosensitive composition that can be developed with a dilute alkaline aqueous solution has recently been used. Examples of such an alkali-developable photosensitive resin composition include, for example, a photosensitive composition having a reaction product obtained by reacting an unsaturated monocarboxylic acid with an epoxy resin and further adding a polybasic acid anhydride as a base polymer. (JP-B-56-40329 and JP-B-57-45)
No. 785) is known, and an alkali developing type photosensitive composition (JP-A-61-243869) using a novolak type epoxy resin and having improved heat resistance and chemical resistance is also used. I have.

In the build-up method, when a wiring pattern is formed by a conductor on a resin insulating film, the surface of the resin insulating film is roughened to improve adhesion between the resin insulating film and the conductor.
A method of performing electroless plating is generally used. In order to roughen the surface of a resin insulating film, a method of forming fine holes by chemical etching on a wiring pattern forming surface of the insulating film has been conventionally known. Specifically, particles soluble in an insulating film by an acid or an alkali, ie, a filler component, are added to the insulating film, and the filler is dissolved or desorbed by an etching treatment (a surface roughening treatment) with an acid or an alkali to form an insulating film. A hole is formed on the surface. As the filler component, for example, calcium carbonate can be used. According to this method, the metal plated as a conductor enters the hole formed on the surface of the insulating film, and the adhesion between the conductor and the resin insulating film is improved by the anchor effect.

Conventionally, the thickness of an insulating film (usually 40 to 100
μm), fillers having an average particle size (particle size corresponding to 50% of the cumulative distribution) of about 1 to 10 μm have been used. These fillers are usually those obtained by grinding and classifying natural minerals (eg, limestone) (eg, heavy calcium carbonate).

[0009]

The conventional epoxy resin used for the insulating film for build-up uses chlorine in the synthesis process (uses a chlorine-containing compound such as epichlorohydrin as a starting material). , Chlorine remains as an impurity in the final product. For this reason, when the insulating layer of the build-up circuit board is formed using these epoxy resins,
There is a problem that the insulating property of the substrate is reduced by the impurity chlorine.

In recent years, electronic circuits have been miniaturized and multilayered.
In addition, with high density mounting of electronic components, high resolution is required for formation of via holes. Via holes having a diameter of about 50 μm have been studied recently, and films constituting a multilayer circuit board are also becoming thinner. . The thickness of the insulating film is usually about 40 to 100 μm, but recently an insulating film having a thickness of about 20 μm is being developed. In such a thinner insulating film, it is particularly important to ensure insulation reliability, and therefore, it is important to reduce impurities in the resin.

[0011] Further, in such an insulating film whose thickness is reduced, a usual filler (particles having an average particle diameter of about 1 to 10 µm obtained by pulverizing and classifying a natural mineral) used so far.
When using, the general roughening of the wet-roughening at the time of forming the wiring layer by copper plating opens an excessive hole in the insulating film,
There is a problem that the insulating property is reduced.

As described above, the conventional technique of adding a filler obtained by pulverizing and classifying a natural mineral is a thin film (film thickness of 20 μm).
There is a problem in that the conductor (copper plating) adhesion, insulation, and resolution cannot all be satisfied with respect to the insulating film (before and after). There is a problem in insulation reliability.

JP-A-9-176 discloses a highly heat-resistant insulating film material for forming an insulating film without using calcium carbonate.
No. 459 has been proposed. Japanese Patent Application Laid-Open No. 9-176559 proposes an insulating film material composed of a thermosetting condensed polycyclic polynuclear aromatic resin and various thermoplastic resins. However, in the insulating film material described in this publication, since a thermoplastic resin is used as an additive, holes are formed due to the particle size of the thermoplastic resin during wet roughening at the time of forming a wiring layer. There is a problem that is difficult. For example, in the case of a polyimide resin, a commercially available granular thermoplastic polyimide (for example,
When UBE-U manufactured by UBE is added, the diameter becomes 10 μm.
An excessively large hole is formed.

According to the present invention, there is provided an insulating film which does not contain impurities such as chlorine which is a cause of deterioration of the insulating property of the formed insulating film, and has a rough surface of the insulating film for ensuring adhesion to the conductor layer. It is an object of the present invention to provide an insulating resin composition capable of responding to a demand for a thinner film without deteriorating the insulating property of the insulating film due to the formation of the resin.

[0015]

The insulating resin composition of the present invention comprises an alicyclic epoxy resin as a base resin, an epoxy curing agent for the base resin, a polybutadiene compound, silica powder, or polyimide by heating. Alternatively, it is characterized by containing a monomer or a precursor that produces polyetherimide.

[0016]

BEST MODE FOR CARRYING OUT THE INVENTION The alicyclic epoxy resin suitable as a base resin in the composition of the present invention includes an alicyclic polyfunctional epoxy resin having a cyclohexane skeleton, an alicyclic bifunctional epoxy resin, and an alicyclic trifunctional epoxy resin. Resin and alicyclic 4-functional epoxy resin. It is also possible to use mixtures of two or more of them. As the polyfunctional epoxy resin having a cyclohexane skeleton, for example, EHPE-3150 available from Daicel Chemical Co., Ltd. can be used. Examples of alicyclic bifunctional epoxy resins include ER
Resins such as L-4299 (Union Carbide), Celloxide 2021 (Daicel Chemical), CY-175 (Ciba Geigy), Celloxide 2080 (Daicel Chemical) can be used. As an alicyclic trifunctional epoxy resin, Eporide GT300 (Daicel Chemical Co., Ltd.)
And an alicyclic tetrafunctional epoxy resin such as Epolide GT400 (Daicel Chemical Co., Ltd.). Such an alicyclic epoxy resin is synthesized without using a chlorine-containing compound such as epichlorohydrin as a starting material, and thus contains impurities such as halogens which cause a decrease in insulation of the formed insulating film. Absent.

The epoxy curing agent for the cycloaliphatic epoxy resin may be a phenol novolak resin, an acid anhydride, etc.
Further, a mixture of a silanol-containing compound and a metal-containing compound may be used as a curing agent.

The epoxy curing agent may contain a curing accelerator. As the curing accelerator, an imidazole compound, triphenylphosphine, or the like can be used.

[0019] The composition of the present invention is an insulating film for ensuring adhesion to a conductor layer, in addition to the above-mentioned curing agent and curing accelerator, which are common components in a composition containing an epoxy resin as a base resin. As a component effective for surface roughening, a polybutadiene compound, a silica powder, or a monomer or precursor which is soluble in an alkaline solution and generates polyimide or polyetherimide by heating is included. These can be used as a mixture.

As the polybutadiene compound, epoxidized polybutadiene, styrene-butadiene copolymer and the like can be used. Typical examples of the epoxidized polybutadiene include Epolide PB3600 and Epolide PB4700 (both manufactured by Daicel Chemical Co., Ltd.). Examples of the styrene-butadiene copolymer include Epofriend A (manufactured by Daicel Chemical Co., Ltd.). Can be mentioned. When the polybutadiene compound is used, the content is preferably 10 to 50% by weight, more preferably 30 to 50% by weight, based on the total weight of the composition of the present invention. When the composition of the present invention uses a solvent, the total weight of the composition means the total weight of components excluding the solvent.

The silica powder has a thickness of 2 μm in order to reduce irregularities formed by the falling off of silica during surface roughening.
It is desirable to use one with the following diameter. The silica powder may be selected from those generally used as a filler and having a diameter as described above. The content of the silica powder is preferably 5 to 30% by weight, more preferably 10 to 20% by weight based on the total weight of the composition of the present invention. When the composition of the present invention uses a solvent, the total weight of the composition means the total weight of components excluding the solvent.

When a polybutadiene compound or silica powder is used, if the content is less than the above lower limit, the surface roughness of the insulating film is insufficient, whereas if it exceeds the upper limit, the mechanical strength of the film is reduced when the silica powder is used. And the peel strength cannot be obtained as in the case where the value is less than the lower limit. In the case of the polybutadiene compound, the peel strength cannot be obtained as in the case where the value is less than the lower limit.

The monomer or precursor which forms polyimide or polyetherimide by heating is dissolved in an alkaline solution by surface roughening treatment after forming the insulating film, or the polyimide or polyetherimide is removable from the film. Or a precursor such as a monomer or oligomer that produces polyetherimide. Such a monomer or precursor is, for example, PIX-
3400 (Hitachi Chemical), Semico Fine (Toray),
It is commercially available as HIMAL (Hitachi Chemical).

These monomers or precursors are preferably present in the composition of the present invention in an amount of from 5 to 50% by weight, particularly preferably from 10 to 30% by weight. When the composition of the present invention contains a solvent, the above weight ratio corresponds to the weight ratio based on the total weight of the components excluding the solvent.

In general, when a composition containing an epoxy resin and a monomer or a precursor that forms a polyimide (or polyetherimide) is heated, either the heat-cured epoxy resin or the polyimide formed by heating has either one. It is considered that the particles are separated into particles having a particle size. The particle size of the granular thermosetting epoxy resin or polyimide changes depending on the type and composition ratio of the monomer or precursor that forms the epoxy resin and polyimide in the original composition. In the composition of the present invention, by setting the polyimide-forming component to 50% by weight or less, particularly preferably 30% by weight or less, the resin insulating film obtained after heating is dipped in an alkaline solution such as a permanganic acid solution. Only the polyimide on the surface layer separates and falls off from the resin film, whereby fine irregularities are formed on the surface layer of the resin insulation film. When electroless copper plating or electrolytic copper plating is performed as a subsequent conductor layer forming step, these fine irregularities act as anchors for the plated copper, and the resin film and the plated copper can be adhered to each other. On the other hand, when the content of the polyimide or polyetherimide-forming component in the composition is less than 5% by weight, the polyimide or polyetherimide is less likely to fall off during the treatment with an alkaline solution, so that the adhesion to the conductor layer to be formed later is reduced. The improvement of the performance cannot be expected.

When polyimide or polyetherimide having excellent heat resistance is used as a filler for surface roughening, the formed insulating layer has improved heat resistance as compared with a conventional insulating layer.

The composition of the present invention is generally applied to a processing substrate as a varnish. In order to obtain a varnish-like composition, the composition of the present invention may contain a suitable solvent in addition to the above components. Examples of the solvent include organic solvents such as ethylene glycol monoethers, acetates, cyclohexanone, dioxane, toluene, xylene, and N-methylpyrrolidone.

As a coating method, a general method such as screen printing, curtain coating, roll coating, and spin coating can be adopted, but the coating method is not limited to these.

Further, various additives can be added to the composition of the present invention as needed. Examples of additives include inorganic fillers such as alumina, which is effective for adjusting the expansion coefficient of the insulating film, and aerosil, which are effective for improving screen printability, as well as coloring pigments such as phthalocyanine, silicone or fluorine-based compounds. Foaming agents, leveling agents, antioxidants and the like can be mentioned.

Next, a method for forming a built-up insulating film of a multilayer circuit board using the resin composition of the present invention will be described. It should be noted that the following description is merely an example of this method, and it goes without saying that the method of forming the insulating film of the multilayer circuit board with the resin composition of the present invention is not limited thereto.

First, the resin composition of the present invention is applied to an electronic circuit board by an appropriate coating method to a desired thickness (for example, 20 μm).
m) to form a film. Next, the film is heated at an appropriate temperature, for example, 50 to 150 ° C., and the film is dried. Next, the epoxy resin component is heated and cured at, for example, 150 to 250 ° C. At this time, if a polyimide or polyetherimide component is used as a filler component, it is also heated and cured to form an insulating film. Form. afterwards,
A portion (via hole portion) to be connected to an upper electronic circuit formed on the insulating film is subjected to laser processing using, for example, a carbon dioxide gas laser, an excimer laser, a YAG laser, or the like to form a via hole.

Subsequently, the substrate is immersed in an alkaline solution such as an aqueous solution of permanganate to roughen the surface. The polybutadiene compound in the insulating film, the silica powder, or the polyimide or polyetherimide obtained by thermal curing dissolves in an alkaline solution, or desorbs due to swelling action by the alkaline solution, and causes fine holes in the insulating film surface. This contributes to roughening of the insulating film surface. Next, the surface roughened insulating film is subjected to electroless plating and electrolytic plating to form a conductor wiring layer and pattern the same. Thereafter, the steps from the application of the resin composition to the formation of the conductor wiring pattern are repeated a predetermined number of times, thereby producing a multilayer circuit board.

As described above, the multilayer circuit board manufactured using the composition of the present invention is a multilayer circuit board including a plurality of insulating layers and a wiring layer formed on a predetermined circuit board, wherein the insulating layer is The invention is characterized by being formed from the composition of the present invention, and the present invention also includes this multilayer circuit board.

[0034]

Next, the present invention will be further described with reference to examples.
Of course, the invention is not limited to these examples.

[Example 1] 60 parts by weight of cyclohexane skeleton alicyclic epoxy resin EHPE-3150 (manufactured by Daicel Chemical), 40 parts by weight of alicyclic epoxy resin celloxide 2080 (manufactured by Daicel Chemical), phenol Novolak resin (PSM-4300 manufactured by Gunei Chemical Co., Ltd.)
60 parts by weight, 4 parts by weight of 2-methyl-4-ethyl-imidazole (manufactured by Shikoku Chemicals), and 30 parts by weight of silica powder (average particle size: 4 μm, manufactured by Denki Kagaku Kogyo) are added to 60 parts by weight of dioxane. A dispersion of silica powder was prepared.

This coating solution is applied on a copper foil substrate to a thickness of 20 μm after drying by a doctor blade method.
After heating and drying at 0 ° C. for 20 minutes and further heating at 170 ° C. for 60 minutes, the resultant was allowed to cool to room temperature to form an insulating layer.

Next, the substrate on which the insulating layer was formed in this manner was treated with a pretreatment agent (conditioner manufactured by Shipley Co.,
Min), an oxidizing agent (aqueous permanganate solution) (promoter from Shipley, 70 ° C., 10 minutes, pH 11), and a neutralizing agent (Nutriser from Shipley, 60 ° C., 10 minutes)
, And the silica powder exposed on the surface of the insulating layer was removed to roughen the surface of the insulating layer.

After cleaning the roughened surface of the insulating layer, electroless copper plating and electrolytic copper plating are successively performed, and 30 μm
An m-thick conductor layer was formed. The peel strength of this conductor layer measured according to the test method specified in JIS C 6481 was 500 g / cm.

Example 2 The coating solution prepared in Example 1 was
The composition was applied onto a bismaleimide / triazine (BT) substrate having a wiring with an interval of 126 μm, and an insulating layer was formed on the wiring in the same manner as in Example 1. With respect to the substrate on which the insulating layer was formed in this manner, 120 ° C., 85% relative humidity, 1.7 at
An electric corrosion test (USPCBT test) for 50 hours was performed under the conditions of m (172 kPa) and 20 V. The resistance between the wirings measured before and after the test was on the order of 1 × 10 ¹³ Ω before the test, and maintained on the order of 1 × 10 ¹³ after the test.

Example 3 60 parts by weight of cyclohexane skeleton alicyclic epoxy resin EHPE-3150 (manufactured by Daicel Chemical Co., Ltd.), 40 parts by weight of alicyclic epoxy resin celloxide 2080 (manufactured by Daicel Chemical Co., Ltd.), phenol Novolak resin (PSM-4300 manufactured by Gunei Chemical Co., Ltd.)
60 parts by weight, 4 parts by weight of 2-methyl-4-ethyl-imidazole (manufactured by Shikoku Chemicals), and 90 parts by weight of epoxidized polybutadiene (PB3700 manufactured by Daicel Chemical Co., Ltd.)
It was dissolved in 60 parts by weight of dioxane to prepare a coating liquid for forming an insulating layer.

This was applied on a copper foil substrate in the same manner as in Example 1, and an insulating layer was formed by heating, followed by alkali solution treatment (surface roughening treatment), followed by electroless copper plating and electrolytic copper plating. To form a copper film. The peel strength of this copper film was 7
It was 00 g / cm.

Further, in the same manner as in the second embodiment,
An insulating layer was formed on a substrate provided with m wirings, and an electrolytic corrosion test was performed. The resistance between the wirings before the test was on the order of 1 × 10 ¹² Ω, and the resistance after the test also maintained on the order of 1 × 10 ¹² Ω.

Example 4 60 parts by weight of cyclohexane skeleton alicyclic epoxy resin EHPE-3150 (manufactured by Daicel Chemical), 40 parts by weight of alicyclic epoxy resin Celloxide 2080 (manufactured by Daicel Chemical), phenol Novolak resin (PSM-4300 manufactured by Gunei Chemical Co., Ltd.)
60 parts by weight, 4 parts by weight of 2-methyl-4-ethyl-imidazole (manufactured by Shikoku Chemicals), and 70 parts by weight of polyimide monovarnish (PIX-3400 manufactured by Hitachi Chemical Co., Ltd.)
-Methylpyrrolidone to prepare a coating solution for forming an insulating layer.

The prepared coating solution was applied to a thickness of 20 μm on a copper foil substrate, and then dried by heating at 120 ° C. for 20 minutes.
After heating at 170 ° C. for 60 minutes, the mixture was allowed to cool to room temperature to form an insulating layer.

The insulating layer was subjected to an alkali solution treatment (surface roughening treatment) in the same manner as in Example 1, and then a copper plating film was formed on the insulating layer. The peel strength of this copper plating film was 800 g / cm.

An electrolytic corrosion test was performed in the same manner as in Example 2. The resistance between the wirings before the test was on the order of 1 × 10 ¹³ Ω, and the resistance after the test also maintained on the order of 1 × 10 ¹³ Ω.

[0047]

As described above, according to the present invention,
By using an alicyclic epoxy resin that does not contain halogen impurities and a filler component that is effective in improving the adhesion to the conductor layer without causing a decrease in insulation, the insulation is superior to conventional ones, and It is possible to use a resin insulating film having excellent adhesion to the layer. In addition, when polyimide or polyetherimide having good heat resistance is used as the surface roughening filler, the heat resistance of the resin insulating film can be improved. Thus, the present invention can greatly contribute to the formation of an insulating film in general, particularly a build-up insulating film for a multilayer circuit board.

──────────────────────────────────────────────────の Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI Theme coat ゛ (Reference) C08L 79/08 C08L 79/08 A C09D 163/00 C09D 163/00 179/08 179/08 Z H01B 3 / 40 H01B 3/40 DCF term (reference) 4J002 AC083 CC04X CD02W CD183 CM044 DJ017 EF126 EL136 EX046 FD14X FD146 GQ01 4J036 AB07 DA01 DB15 FB07 JA08 4J038 CA021 CA022 DA042 DB261 DJ021 DJ022 HA446 JA75 JC33A09BA03 NA03 NA031 CA08 CA15 CA21 CA23 CA27 CB13 CB15 CB26 CB27 CC02 CD08

Claims (5)

[Claims] 1. An epoxy resin comprising: an alicyclic epoxy resin; an epoxy curing agent for the resin; a polybutadiene compound, silica powder, or a monomer or precursor that produces a polyimide or polyetherimide by heating. A characteristic insulating resin composition. 2. The composition according to claim 1, wherein the alicyclic epoxy resin is an epoxy resin having a cyclohexane skeleton. 3. The epoxy resin having a cyclohexane skeleton according to claim 2, wherein the epoxy resin is a bifunctional epoxy resin, a trifunctional epoxy resin, or a tetrafunctional epoxy resin, or a mixture of two or more thereof. Composition. 4. The composition according to claim 1, wherein the epoxy curing agent is a phenol novolak resin or an acid anhydride, or a mixture of a silanol-containing compound and a metal-containing compound. . 5. A multilayer circuit board including a plurality of insulating layers and a wiring layer formed on a predetermined circuit board, wherein the insulating layer comprises an alicyclic epoxy resin, an epoxy curing agent for the resin, A multilayer circuit board, comprising: an insulating resin composition containing a polybutadiene compound, silica powder, or a monomer or precursor that generates polyimide or polyetherimide by heating.