JP2000306429A - Insulation composition and multilayer wiring plate - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an insulator with less deterioration in bonding strength between an insulating layer and a plated layer and insulating performance of the insulating layer under a high temperature and moisture by including photosensitive resin, alkylated melamine resin and aluminum hydroxide as essential components. SOLUTION: As alkylated melamine resin, methylated melamine resin, n- butylated melamine resin, and i-butylated melamine resin are listed. Independent use and combining use of two or more kinds are allowable. Degree of etherification of the alkylated melamine resin is not limited. As photosensitive resin, limitation does not exists, and use of compounds having a functional group capable of crosslinking directly by irradiation of light or under existence of a photo polymerization initiator by irradiation of light is allowable. From the standpoint for giving heat resistance to an insulating layer, compounds such as epoxy acrylate and phthalic acid modified epoxy acrylate are preferable.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to an insulating material composition and a multilayer wiring board.

[0002]

2. Description of the Related Art An ordinary multilayer wiring board is manufactured as follows. First, a copper foil is laminated via a prepreg on an inner layer circuit board on which an inner layer circuit is formed on an insulating substrate, and these are laminated and integrated by heating and pressing. Next, a through hole is formed at a place where each circuit layer is electrically connected. Next, plating is deposited on the inner wall of the through hole and the copper foil surface by electroless plating. When the thickness of the circuit conductor is insufficient with only the plating deposited by electroless plating, the plating is compensated by depositing the plating by electrolytic plating.
Finally, a surface circuit is formed by etching.

[0003] In recent years, the miniaturization, weight reduction, and multifunctionality of electronic devices have been further advanced, and with this, the integration of LSIs and chip parts has been advanced, and the form has rapidly changed to multipins and miniaturization. are doing. For this reason, in order to improve the mounting density of electronic components, development of fine wiring has been promoted for multilayer wiring boards. However, there is a technical limit in reducing the wiring width, and the wiring width that can be mass-produced at present is 75 to 100 μm. Therefore, it is difficult to greatly increase the wiring density simply by reducing the wiring width. A bottleneck in improving the wiring density in the multilayer wiring board is that the diameter is 300 mm.
This is a through hole having a thickness of about μm and thus occupying a large area. This through hole is generally relatively large in size for drilling with a mechanical drill,
Since the hole penetrates the entire wiring board, a portion that does not require electrical connection is occupied by the hole, so that the degree of freedom in wiring design is reduced. Therefore, an insulating layer between circuit layers is formed using an insulating material composition mainly composed of a photosensitive resin, and a hole (via hole) that penetrates only the insulating layer is formed by a photo process instead of drilling with a mechanical drill, A method of forming an electrical connection between circuit layers by depositing plating on the inner wall of a via hole has been proposed (Japanese Patent Publication No. 4-555).
55, JP-A-63-126296).
According to the photo process, fine drilling is possible.
In addition, since holes are formed for each insulating layer, holes can be formed only in portions that require electrical connection, and the degree of freedom in wiring design is increased. Therefore, the wiring density can be increased.

[0004] Insulating materials used when forming via holes by a photo process include photosensitivity that is polymerized by irradiation with light (usually ultraviolet light), insulating properties when an insulating layer is formed, and adhesion to plating. In order to impart these characteristics, a composition containing various components as a main component of a photosensitive resin is used.

[0005]

However, in recent years, the use conditions of electronic equipment have become severe, and electronic components have also become surface-mounted. Accordingly, even under high temperature and high humidity, the insulating layer and the plating have to be formed. It is required that the adhesion between the insulating layer and the insulating layer be small. The present invention
In order to meet such a demand, an object is to provide an insulating material composition and a multilayer wiring board having low adhesion strength between an insulating layer and plating and insulating layer insulation even under high temperature and high humidity.

[0006]

The invention according to claim 1 is an insulating material composition comprising a photosensitive resin, an alkylated melamine resin and aluminum hydroxide as essential components.

[0007] The invention described in claim 2 is the first invention.
A multilayer wiring board formed by forming an insulating layer between circuit layers using the insulating material composition described in 1. above.

[0008]

BEST MODE FOR CARRYING OUT THE INVENTION As the alkylated melamine resin used in the present invention, for example, a methylated melamine resin,
Various alkylated melamine resins such as an n-butylated melamine resin and an i-butylated melamine resin are exemplified. These may be used alone or in combination of two or more. The degree of etherification of the alkylated melamine resin is not particularly limited.

As the aluminum hydroxide used in the present invention, commercially available aluminum hydroxide can be used.
There is no particular limitation. Because it is blended into the insulating material composition,
Those having an average particle size in the range of 0.5 to 5 μm are preferred. If the average particle size is less than 0.5 μm, the adhesion strength between the plating and the insulating layer tends to be insufficient, and if the average particle size exceeds 5 μm, the irregularities on the surface of the insulating layer become large and are used in a photo process. The adhesiveness between the photomask and the insulating layer becomes insufficient, and the resolution when forming an image of a via hole (hereinafter referred to as via resolution) tends to decrease.

The amount of aluminum hydroxide is preferably in the range of 5 to 30 parts by weight based on 100 parts by weight of the insulating material composition excluding the alkylated melamine resin and aluminum hydroxide. The amount of aluminum hydroxide is 5
If the amount is less than the weight part, the adhesion strength between the insulating layer and the plating under high temperature and high humidity and the insulation resistance maintaining property tend to decrease.
If it exceeds 0 parts by weight, via resolution tends to decrease. The amount of the alkylated melamine resin is preferably in the range of 5 to 50 parts by weight based on 100 parts by weight of aluminum hydroxide. If the compounding amount of the alkylated melamine resin is less than 5 parts by weight, the adhesion strength between the insulating layer and the plating under high temperature and high humidity tends to decrease. The storage stability tends to decrease when the film is formed or when the solvent is removed from the varnish to form a film.

The photosensitive resin which is a main component in the insulating material composition of the present invention is not particularly limited, and is a functional group which can be crosslinked directly by irradiation of light or in the presence of a photopolymerization initiator by irradiation of light. Can be used. From the viewpoint of imparting heat resistance to the insulating layer, it is preferable to use a compound having such a functional group and a heat-resistant skeleton, such as epoxy acrylate, phthalic acid-modified epoxy acrylate, urethane acrylate, and polyester acrylate. Commercial products can be used as the photopolymerization initiator, and there is no particular limitation.

In order to impart heat resistance to the insulating layer, a thermosetting resin such as an epoxy resin, a phenol resin, a melamine resin, and a cyanate ester resin in addition to the photosensitive resin is used as long as it does not affect the exposure and development in the photo process. It is preferable to use them in combination. Among them, an epoxy resin is preferable because, in addition to heat resistance, the insulating property of the insulating layer and the adhesion between the insulating layer and the plating are improved. As the epoxy resin, bisphenol A type epoxy resin, bisphenol F type epoxy resin, bisphenol S type epoxy resin, phenol novolak type epoxy resin, cresol novolak type epoxy resin, alicyclic epoxy resin, glycidyl ester type epoxy resin, glycidylamine type An epoxy resin, a hydantoin type epoxy resin, an isocyanurate type epoxy resin, and the like can be given. A halogenated epoxy resin to which halogen such as bromine is added, or a hydrogenated epoxy resin to which hydrogen is added may be used. These epoxy resins may be used alone or in combination of two or more as needed. When it is necessary to make the insulating layer flame-retardant, it is preferable to incorporate a halogenated epoxy resin, for example, a brominated epoxy resin.

Natural rubber, acrylic rubber, carboxylic acid-modified acrylic rubber, natural rubber, acrylic rubber, and carboxylic acid-modified acrylic rubber are used to impart flexibility to the insulating layer and roughen the surface of the insulating layer to improve the adhesion of plating.
It is preferable to mix rubber components such as styrene-butadiene rubber, acrylonitrile-butadiene rubber, carboxylic acid-modified acrylonitrile-butadiene rubber, cross-linked acrylonitrile-butadiene rubber, and carboxylic acid-modified cross-linked acrylonitrile-butadiene rubber. Since these rubber components are easily decomposed by the oxidizing chemical solution, the oxidizing chemical treatment serves to form irregularities on the surface of the insulating layer, thereby improving the adhesion between the insulating layer surface and the plating. Further, an epoxy resin modified by such a rubber component or an epoxy resin in which such a rubber component is dispersed can be used.

The photosensitive resin, the thermosetting resin and the rubber component are added to the thermosetting resin 1 per 100 parts by weight of the photosensitive resin.
It is preferable to mix in the range of 0 to 100 parts by weight and the rubber component in the range of 5 to 100 parts by weight.
More preferably, it is blended in the range of 50 parts by weight. If the thermosetting resin is less than 10 parts by weight, electrical insulation and heat resistance tend to decrease, and if it exceeds 100 parts by weight, adhesion strength to plating tends to decrease. If the rubber component is less than 5 parts by weight, the adhesion strength to plating tends to decrease, and if it exceeds 100 parts by weight, electrical insulation tends to decrease.

Next, a process of manufacturing a multilayer wiring board using the insulating material composition of the present invention will be described with reference to FIG.

First, a circuit board 3 having a circuit layer 1a formed on an insulating substrate 2 is prepared (see FIG. 1A). The insulating substrate 2 is a known laminate used in a normal wiring board, for example, a glass cloth base epoxy resin laminate, a paper base phenol resin laminate, a paper base epoxy resin laminate, a glass cloth and glass. A composite epoxy resin laminate having paper as a base material is used, and there is no particular limitation. There is no particular limitation on the method of forming the circuit layer 1a. A subtractive method is used in which a copper clad laminate in which a copper foil is adhered to the surface of the insulating substrate 2 is used, and the copper foil other than the portion left as a circuit pattern is etched. A known method of manufacturing a wiring board, such as an additive method of forming a circuit pattern on the insulating substrate 2 by electroless plating, or the like, can be used. FIG. 1A shows an example in which the circuit layer 1a is formed on one surface of the insulating substrate 2, but the circuit layer 1a may be formed on both surfaces of the insulating substrate 2 using a double-sided copper-clad laminate. it can.

Next, the surface of the circuit layer 1a is roughened. In this step, the surface is oxidized with an alkaline aqueous solution of sodium hypochlorite to form copper oxide needle-like crystals, and the formed copper oxide needle-like crystals are immersed in an aqueous dimethylamine borane solution and reduced. And there is no particular limitation.

Next, an insulating material composition layer 4b is formed on the surface of the circuit layer 1a (see FIG. 1- (b)). As a method for forming the insulating material composition layer 4b, a method of applying a varnish of the insulating material composition by a method such as screen printing, dip coating, roll coating, curtain coating, or the like, and forming the insulating material composition in a film or sheet form. And a method of laminating and laminating them. Further, the thickness of the insulating material composition layer 4b is not particularly limited, and is usually appropriately selected in the range of 20 to 200 μm.

Next, a via hole 7 connected to the circuit layer 1a is formed.
The light beam 6c is applied to the insulating material composition layer 4b through a photomask 5c formed so as to mask a portion where d is to be formed.
Exposure to irradiate (Ultraviolet light is usually used as a light source,
The same method as that for forming a normal wiring board is used (see FIG. 1- (c)).

Next, the unexposed portion of the insulating material composition layer 4b is developed by a method of etching with a developer to form a via hole 7d (see FIG. 1- (d)). The method of etching with a developer can be a known method and is not particularly limited. For example, a method of spraying a developer or dipping in a developer may be used. The developer is determined depending on the type of development of the insulating material composition, but a general developer such as an alkali developer, a quasi-aqueous developer, or a solvent developer can be used. After the development, post-exposure is performed by irradiating light rays as necessary, and further post-curing is performed by heating to form the insulating material composition as the insulating layer 8d. The heating condition at this time is not particularly limited as long as the insulating material composition layer 4b is appropriately cured.

Next, the surface of the insulating layer 8d is roughened by treatment with an oxidizing roughening solution. As the oxidizing roughening solution, a roughening solution of chromium / sulfuric acid, a roughening solution of alkali of permanganic acid, a roughening solution of sodium fluoride / chromium / sulfuric acid, a roughening solution of borofluoric acid, or the like can be used. Next, it is immersed in an aqueous hydrochloric acid solution of stannous chloride to neutralize and perform a sensitizing treatment for attaching tin ions, and further, a plating catalyst applying treatment for attaching palladium. The plating catalyst application treatment is performed by dipping in a palladium chloride-based plating catalyst solution. Next, by dipping in an electroless plating solution, electroless plating having a thickness of 0.3 to 1.5 μm is deposited thereon. Electroplating is further performed if necessary.
As the electroless plating solution used for the electroless plating, a known electroless plating solution can be used, and there is no particular limitation. Also, the electroplating can be performed by a known method, and there is no particular limitation. Next, circuit processing is performed on the plating thus formed to form a circuit layer 1e and an interlayer connection between the circuit layers 1a and 1e (FIG. 1).
(E)). As a method for forming the circuit layer 1e, a method in which a plating catalyst is contained in an insulating material composition, a plating resist is formed on the surface of the insulating layer 8d, and a circuit is formed by electroless plating only at a necessary portion; Alternatively, a method may be used in which a circuit is formed by electroless plating only at a necessary portion after forming a plating resist after roughening an insulating layer and applying a plating catalyst in the same manner as described above.

Thereafter, the circuit layer 1e is roughened in the same manner as the circuit layer 1a, and thereafter, the insulating material composition layer 4f is formed in the same manner as the formation of the circuit layer 1e (FIG. 1- (f)). )), The insulating material composition layer 4f through the photomask 5g.
Is exposed to light 6g (see FIG. 1- (g)), and the unexposed portion of the insulating material composition layer 4f is developed by etching using a developing solution to form a via hole 7h. The material layer 4f is cured to form the insulating layer 8h (see FIG. 1- (h)), and the circuit layer 1i is formed (FIG. 1-).
(See (i)). Thereafter, by repeating the same steps, a multilayer wiring board having a large number of layers can be manufactured.

[0023]

EXAMPLES Example 1 (1) Glass cloth-based epoxy resin double-sided copper-clad laminate (copper foil having a thickness of 18 μm and roughened copper foil on both sides manufactured by Hitachi Chemical Co., Ltd., MCL-E) -67 (trade name) was used to produce a circuit board having circuit layers (hereinafter referred to as first circuit layers) on both surfaces. (2) 70 parts by weight of phthalic acid-modified novolak type epoxy acrylate (R-5259 (trade name) manufactured by Nippon Kayaku Co., Ltd.) and carboxylic acid-modified polybutadiene (Hiker CTBN1300X13 (trade name) manufactured by Ube Industries, Ltd.) Use) 10 parts by weight, phenol novolak type brominated epoxy resin, (Nippon Kayaku Co., Ltd., BREN-
S (trade name)) 15 parts by weight, photopolymerization initiator, 5 parts by weight (Circa Geigy Co., Ltd., Irgacure 651 (trade name)), aluminum hydroxide (average particle size 1.5 μm)
m, 15 parts by weight of Heidilite H-42M (trade name) manufactured by Showa Denko KK and 5 parts by weight of methylated melamine resin (Melan 523 (trade name) manufactured by Hitachi Chemical Co., Ltd.) Thus, an insulating material composition was prepared. The prepared insulating material composition was applied to one side of the circuit board prepared in the above (1) using a roll coater so that the thickness after drying was 50 μm, and dried at 80 ° C. for 10 minutes. (3) Next, an ultraviolet ray is irradiated through a photomask in which a shielding portion is formed in a portion to be a via hole (exposure amount: 300 m
J / cm ² ), and then a developing solution (2-2-butoxyethoxyethanol: 10 vol%, sodium 4-borate:
(8 g / liter) at 30 ° C. for 1 minute to form a via hole. (4) Next, for post-exposure, ultraviolet irradiation (exposure amount 2 J
/ Cm ² ). (5) Next, post-heating was performed at 150 ° C. for 1 hour to form an insulating layer having via holes. (6) Next, a roughening solution (KMnO ₄ : 60 g / liter,
(NaOH: 40 g / liter aqueous solution) at 50 ° C. for 5 minutes to roughen the surface of the insulating layer. Subsequently, a neutralization solution (SnCl ₂ : 30 g / liter, concentrated hydrochloric acid: 300 ml)
/ L aqueous solution for 5 minutes at room temperature to neutralize and sensitize the surface of the insulating layer. (7) Next, the catalyst for electroless plating was immersed in a catalyst solution for electroless plating (a palladium chloride type, using HS-202B (trade name) manufactured by Hitachi Chemical Co., Ltd.) at room temperature for 10 minutes and washed with water. Then, it is immersed in an electroless copper plating solution (L-59 (trade name) manufactured by Hitachi Chemical Co., Ltd.) at 70 ° C. for 30 minutes, and further subjected to copper sulfate electrolytic plating to insulate. A 20 μm-thick plating is formed on the surface of the layer, an etching resist for etching and removing unnecessary portions of the plated conductor is formed, and the steps of etching and etching resist removal are sequentially performed. ), A circuit layer (hereinafter referred to as a second circuit layer) and a via-hole connection between the second circuit layer and the first circuit layer were formed on the surface of the insulating layer formed in step (1). (8) Next, the surface of the second circuit layer is roughened (aqueous solution of sodium chlorite: 50 g / liter, NaOH: 20 g / liter, trisodium phosphate: 10 g / liter).
The substrate was immersed in water at 85 ° C. for 20 minutes, washed with water, and then dried by heating at 80 ° C. for 20 minutes to oxidize the conductor surface of the second circuit layer to form copper oxide irregularities. (9) The insulating material composition prepared in the above (2) is applied to the second circuit layer on which the copper oxide unevenness is formed by using a roll coater so that the thickness after drying becomes 50 μm.
Dry for 0 minutes. Thereafter, by performing the same steps as in the above (3) to (7), a circuit layer (hereinafter referred to as a third circuit layer) and a via hole connection between the third circuit layer and the second circuit layer are formed, thereby forming four layers. Was produced.

Example 2 Four layers were prepared in the same manner as in Example 1 except that the methylated melamine resin was changed to an n-butylated melamine resin (Melan X-66 (trade name) manufactured by Hitachi Chemical Co., Ltd.). Was produced.

Example 3 A methylated melamine resin was converted to an iso-butylated melamine resin (Melan-269 (trade name) manufactured by Hitachi Chemical Co., Ltd.).
Was used in the same manner as in Example 1 except that the multilayer wiring board was made of four layers.

Example 4 Example 1 was repeated except that Cylan-300 (trade name) manufactured by Mitsui Cytec Co., Ltd. was used as the methylated melamine resin instead of Melan 523 (trade name) manufactured by Hitachi Chemical Co., Ltd. In the same manner as described above, a four-layer multilayer wiring board was produced.

Comparative Example 1 A multilayer wiring board having four layers was produced in the same manner as in Example 1 except that the methylated melamine resin and aluminum hydroxide were not blended.

With respect to the four-layered multilayer wiring board manufactured as described above, the via resolution, peel strength (adhesion between the insulating layer and the plating), and interlayer insulation resistance were examined as described below. Table 1 shows the results. Via resolution: In a process corresponding to (3) of Example 1, a photomask is provided with a circular black circle shielding portion having a diameter of 0.05 to 0.15 mm and an interval of 0.01 mm to form a minimum shielding in which a via hole can be formed. The diameter of the part was defined as the via resolution (unit: mm). Peel strength: width 1 on a part of the third circuit layer
A portion having a length of 0 mm and a length of 100 mm was formed. One end of the portion was peeled off, gripped with a gripper, and a load was measured when the film was peeled off approximately 50 mm in the vertical direction (unit: kN / m).
Table 1 shows the results of measurements under normal conditions and after holding for 48 hours in a pressure cooker tester at 121 ° C. and 100% RH (in Table 1, denoted as PCT-48). Interlayer insulation resistance: The insulation resistance between the second circuit layer and the third circuit layer was measured using a test piece cut out so as not to include the connection between the circuit layers by the via hole (unit: × 10G)
Ω). Normal and 121 ° C, 100% as well as peel strength
The results measured after holding for 48 hours in an RH pressure cooker tester (in Table 1, denoted as PCT-48) are shown.

[0029]

[Table 1]

From Table 1, it is shown that the via resolution, which is an important characteristic in the photo process, is the same in the four-layer multilayer wiring boards of Examples 1 to 4 and Comparative Example 1. In a four-layer multilayer wiring board,
Although the decrease in peel strength is small even at a high temperature and high humidity of 121 ° C. and 100% RH, the peel strength of the four-layered multilayer wiring board of Comparative Example 1 is remarkably reduced, and the interlayer insulation resistance is reduced. Regarding the degree of decrease, it is shown that the four-layer multilayer wiring board of Comparative Example 1 is larger than the four-layer multilayer wiring boards of Examples 1 to 4 by one digit or more.

[0031]

By using the insulating material composition according to the present invention, the adhesion between the insulating layer and the plating and the insulating property of the insulating layer at high temperature and high humidity can be maintained while maintaining the characteristics required for the photo process. The decrease can be reduced.

[Brief description of the drawings]

FIGS. 1A to 1I are cross-sectional views illustrating steps for manufacturing a multilayer wiring board.

[Explanation of symbols]

 1a, 1e, 1i Circuit layer 2 Insulating substrate 3 Circuit board 4b, 4f Insulating material composition layer 5c, 5g Photomask 6c, 6g Light beam 7d, 7h Via hole 8d, 8h Insulating layer

──────────────────────────────────────────────────の Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI Theme coat ゛ (Reference) H01B 3/30 H01B 3/30 H H05K 3/46 H05K 3/46 T (72) Inventor Masaki Morita Ibaraki 1500 Shimodate, Shimodate-shi, Hitachi Chemical Industry Co., Ltd., Shimodate Research Laboratory (72) Inventor Takashi Yamadera 1500 Shimodate, Shimodate-shi, Ibaraki Prefecture, Hitachi Chemical Industry Co., Ltd. 1500 Hitachi Chemical Industry Co., Ltd. Shimodate Factory (72) Inventor Hiroyuki Fukai 1500 Oji Ogawa, Shimodate City, Ibaraki Prefecture Hitachi Chemical Industry Co., Ltd. Shimodate Factory F-term (reference) BA10A BA10B CA08A DG00B EJ82B GB43 JB07 JB14A JG04 JJ03 JK06 4J002 CC182 CD182 CF191 CK021 DE146 FD201 G Q01 GQ05 5E346 CC08 CC16 HH08 5G303 AA05 AA07 AB01 AB20 BA02 BA12 CA01 CA09 CB01 5G305 AA06 AA11 AB01 AB34 BA09 BA15 BA18 CA07 CA28 CA54 CC03 CD13

Claims (2)

[Claims] 1. An insulating material composition comprising a photosensitive resin, an alkylated melamine resin and aluminum hydroxide as essential components. 2. A multilayer wiring board comprising an insulating layer between circuit layers formed by using the insulating material composition according to claim 1.