JPH0637448A - Adhesive sheet for wiring board - Google Patents

Abstract

PURPOSE:To provide a flexible adhesive sheet for wiring boards by controlling the molecular-weight distribution of an epoxy matrix as well as the proportion of the residual solvent in an adhesive layer. CONSTITUTION:Adhesive solution 14 is applied to a polypropylene film 6 and dried in an IR furnace 7, and the polypropylene film is attached to a polyethylene film 5. While the polyethylene film is peeled, the polypropylene film is attached to the roughened surface of an epoxy-glass substrate 1 with heat and pressure using a laminator. The polypropylene film is removed and the adhesive is cured. The substrate coated with an adhesive layer 2 is drilled and then immersed in oxidizing solution to roughen the adhesive layer. The substrate is rinsed in neutralizing solution and then activated by a palladium catalyst. The substrate is heated and laminated with a dry film, and it is exposed to light and developed to form a resist 3 for electroless copper plating. It is possible to improve the productivity of a printed-circuit board by using a flexible adhesive sheet in this manner.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an adhesive sheet for wiring boards, and in particular, it has flexibility without impairing chemical resistance, heat resistance, electrical characteristics and adhesion with electroless plating film. The present invention proposes an excellent sheet-shaped adhesive (that is, an adhesive sheet).

[0002]

2. Description of the Related Art In recent years, with the progress of the electronic industry, electronic devices have been downsized or speeded up. for that reason,
Printed wiring boards mounted on such electronic devices and printed wiring boards on which LSI is mounted are required to have higher density and higher reliability than ever before.

Conventionally, as a method of forming a conductor circuit in the production of a printed wiring board, an "etched foil method" is known in which a conductor circuit is formed by laminating a copper foil on a substrate and then photoetching the copper foil. ing. According to this method, it is possible to form a conductor circuit having excellent adhesion to the substrate, but there is a major drawback that it is difficult to obtain a highly accurate fine pattern by etching because the copper foil is thick, and further manufacturing There was a problem that the process was complicated and inefficient.

Therefore, recently, as a method of forming a conductor on a printed wiring board substrate, an adhesive containing diene-based synthetic rubber is applied to the surface of the substrate to form an adhesive layer. A so-called "additive method" is used in which the surface is roughened and then electroless plating is applied to form a conductor.

However, since the adhesive generally used in this method contains a synthetic rubber, it has poor heat resistance and, for example, the adhesion strength is greatly reduced at high temperatures, and the electroless plating film is used during soldering. It has a drawback that it is blistered and that electric properties such as surface resistance are not sufficient, so that its use range is considerably limited.

On the other hand, the inventor has solved the drawbacks of the adhesive for applying the electroless plating as described above,
We have proposed an adhesive for electroless plating, which has excellent heat resistance, electrical characteristics, and adhesion to an electroless plated film, and is relatively easy to carry out, and a method for producing a wiring board using this adhesive (Japanese Patent Laid-Open No. 2000-242242). 61-276875). That is, in this conventional technique, a pre-cured heat-resistant resin powder that is soluble in an oxidant is in an uncured heat-resistant resin liquid that exhibits a property of being hardly soluble in an oxidant when subjected to a curing treatment. An adhesive characterized in that it is dispersed in, and after applying this adhesive to a substrate, it is dried and cured to form an adhesive layer, and the fine powder dispersed in the surface portion of the adhesive layer. Is melted and removed to roughen the surface of the adhesive layer, and then electroless plating is applied to the printed wiring board.

According to this prior art, in the above adhesive, the heat-resistant resin fine powder which has been previously cured is dispersed in the heat-resistant resin liquid, and when this adhesive is applied to the substrate and dried and cured, the matrix is formed. The heat-resistant resin fine powder is uniformly dispersed in the heat-resistant resin forming the. Since the heat-resistant resin fine powder and the matrix heat-resistant resin have different solubilities with respect to an oxidizing agent, they are dispersed on the surface portion of the adhesive layer by treating the adhesive layer with an oxidizing agent. The fine powder is mainly dissolved and removed, an effective anchor dent is formed, the surface of the adhesive layer can be uniformly roughened, and high adhesion strength with the electroless plating film and high reliability can be obtained.

However, in this prior art, the printed wiring board is manufactured mainly by coating on the substrate. Therefore, the coating conditions such as viscosity and thixotropy are controlled during the manufacturing process. However, there is a problem that it is very complicated and the productivity is low.

Therefore, in manufacturing a printed wiring board, in order to improve the productivity of the printed wiring board, a technique of forming an adhesive suitable for the above-mentioned electroless plating into a film (so-called an adhesive sheet). Was desired to be developed. In order to meet such demands, JP-A-49-101863 and JP-A-58-164289 propose a film adhesive of a rubber-based resin containing an acrylonitrile rubber having a flexible skeleton as an essential component. ing.

There is also a technique for forming a dry film of a photosensitive adhesive for a plating resist, which contains a binder resin having a molecular weight of 100,000 or more as an essential component.

[0011]

However, the conventional film adhesives still have many problems to be solved. This is because the epoxy resin used in conventional film adhesives has a rigid skeleton, so it is difficult to make a flexible film even when applied to the above film forming technology as a binder resin. there were. From this, it is the actual situation that the film forming technology using an epoxy resin as a main component has not been established.

An object of the present invention is to advantageously solve the problems of the above-mentioned conventional techniques, and particularly to impair the chemical resistance, heat resistance, electrical characteristics and adhesion to the electroless plating film. In order to improve the productivity of printed wiring boards, we have developed an adhesive sheet with excellent flexibility.

[0013]

Means for Solving the Problems In order to solve the above-mentioned problems, the inventor has conducted extensive studies on the properties of an adhesive consisting of an epoxy resin matrix and a heat-resistant resin fine powder.
The inventors have found that it is possible to form an epoxy resin adhesive film by controlling the molecular weight distribution of the epoxy resin matrix and the residual solvent ratio of the adhesive layer, and completed the present invention.

That is, the adhesive sheet for a wiring board according to the present invention is obtained by subjecting a pre-cured heat-resistant resin fine powder soluble in an acid or an oxidant to a sparingly soluble in an acid or an oxidant when subjected to a curing treatment. In an adhesive sheet formed by forming an adhesive layer in the form of a sheet, which is dispersed in an uncured epoxy resin matrix exhibiting the following characteristics, the epoxy resin matrix having a molecular weight of 1000 or less is at least 20 The adhesive sheet for wiring boards is characterized in that the amount of the solvent contained in the adhesive layer is 0.5 to 3.0 wt% and the adhesive layer is formed on the base film. Is desirable.

[0015]

The inventor has conducted various studies on sheet formation (film formation) of an adhesive consisting of an epoxy resin matrix and a heat resistant resin fine powder. As a result, by using an epoxy resin matrix containing at least 20 to 80 wt% with a molecular weight of 1000 or less, and making the amount of solvent remaining in the adhesive layer 0.5 to 3.0 wt%, chemical resistance and heat resistance can be improved. The inventors have found that it is possible to impart sufficient flexibility as an adhesive sheet for wiring boards without impairing the electrical characteristics and the adhesion with the electroless plating film.

Next, in order to make the adhesive into a sheet, the molecular weight is
A resin matrix containing at least 20 to 80 wt% of an epoxy resin of 1000 or less is used. The reason for this is
To obtain the flexibility required for a sheet, a molecular weight of 1000
This is because it is necessary to contain at least 20% by weight of the following epoxy resins, and on the other hand, if it exceeds 80% by weight, B stage cannot be obtained even if a predetermined amount of solvent is removed, and sheet formation becomes difficult.

With respect to such an adhesive, the amount of solvent remaining in the adhesive layer is 0.5 to 3.0 wt%. The reason for limiting the residual solvent amount in this way is that it is possible to impart some flexibility to the adhesive sheet only by controlling the molecular weight of the epoxy resin matrix described above, but it is sufficient as an adhesive sheet for wiring boards. This is because flexibility is not imparted. In particular, the reason for limiting the residual solvent amount to 0.5 to 3.0 wt% is that if it is less than 0.5 wt%, sufficient flexibility as an adhesive sheet for wiring boards cannot be obtained.
This is because if it exceeds 3.0 wt%, the tackiness becomes too large and edge fusion easily occurs.

Since the adhesive sheet of the present invention having the above-mentioned epoxy resin as the resin matrix is extremely excellent in flexibility, the viscosity of the adhesive and the thixotropy of the adhesive are different from those in the past when manufacturing a printed wiring board. There is no need to control the coating conditions such as properties. Moreover, since the adhesive to be laminated on the substrate is in the form of a sheet in advance, it is possible to prepare an adhesive layer satisfying all the conditions such as the film thickness and the peel strength in advance. The productivity can be remarkably improved.

The term "containing at least 20 to 80 wt% of an epoxy resin having a molecular weight of 1000 or less" means that a resin having a large molecular weight (hereinafter, R) has a molecular weight M of 10 or less.
00 <M ≦ 100,000, preferably 1000 <M ≦ 5000, and the resin having a small molecular weight (hereinafter, represented by r) has a molecular weight m of 20.
It is preferable that 0 <m ≦ 1000, preferably 300 ≦ m ≦ 800, and the mixing ratio thereof is 0.2 ≦ r / (r + R) ≦ 0.8 in terms of weight ratio. Further, in order to keep the melting point of the mixed resin at room temperature or higher, it is preferable that the melting point of the resin R is in the range of 50 to 150 ° C and the melting point of the resin r is in the range of 10 to less than 50 ° C.

The reason why the above-mentioned restrictions are preferable is that, among the following characteristics required for film formation,
Since a resin having a small molecular weight is effective against-and a resin having a large molecular weight is effective against-, if the molecular weight and the compounding ratio deviate from the above range, the characteristics of-will be deteriorated. is there. Tack property (adhesiveness of the adhesive surface), flexibility (flexibility), cutting property (whether it cuts cleanly without breaking when cut), edge fusion property (when the film is set up, the adhesive layer is Is it flowing and does it flow?),
And resistance to acids and oxidants.

When the above-mentioned mixed resin of low molecular weight and high molecular weight is used as the resin matrix, the peel strength of the adhesive layer can be 2 kg / cm or more. The reason for this is not clear, but when a mixed resin is used, the high molecular weight resin has the effect of reducing internal stress due to curing shrinkage, and the low molecular weight resin has the effect of being highly reactive and improving the curing rate. It is considered that the synergistic effect increases the breaking strength of the resin. As a result, the roughness of the roughened surface can be reduced, so that a finer pattern can be formed.

The epoxy resin used as the resin matrix in the present invention is preferably used by dissolving it in a solvent. Therefore, the viscosity can be easily adjusted and the resin fine powder described later can be uniformly dispersed. Moreover, this epoxy resin matrix has the property of being easily applied onto the base film.

The solvent used for dissolving the epoxy resin is usually a solvent such as methyl ethyl ketone,
Methyl cellosolve, ethyl cellosolve, butyl cellosolve, butyl cellosolve acetate, butyl carbitol, butyl cellulose, tetralin, dimethylformamide, normal methylpyrrolidone and the like can be used.

Next, the adhesive sheet for a wiring board of the present invention is
It contains a heat-resistant resin fine powder for forming anchors.
Due to the presence of the heat-resistant resin fine powder, when the adhesive layer is formed on the base film, the repelling of the adhesive to the base film can be prevented and the adhesive layer on the base film can be made uniform. This effect is obtained by containing the heat-resistant resin fine powder in an amount of 10 to 60 wt% with respect to the entire adhesive.

Further, this heat-resistant resin fine powder is necessary for forming an effective anchor dent on the roughened surface of the adhesive layer, and such an anchor dent does not form a bond with the adhesive layer. The adhesion with the electrolytic plating film can be improved.

The heat-resistant resin fine powder for forming an anchor used in the present invention needs to be previously cured. The reason for this is that if resin fine powder that has not been cured is used, the resin fine powder will dissolve in the solvent, making it impossible to exert the function as the anchor forming resin fine powder. Therefore, the heat-resistant resin fine powder for anchor formation that has been pre-cured can form a clear anchor without being attacked by the residual solvent, and since the adhesive can be diluted with the solvent, it can be uniformly distributed in the matrix. Can be dispersed in.

As such a fine powder of heat-resistant resin for forming an anchor, it is desirable to use a fine powder of an amino resin such as an epoxy resin, a melamine resin, a guanamine resin or a urea resin. Above all, it is desirable to use an epoxy resin having a molecular weight between cross-linking points of 1000 or more and cured with an amine-based curing agent. The reason for this is that if the molecular weight between cross-linking points is 1000 or more, the cross-linking density will be low and the solubility of the resin will be improved. This is because it is easily dissolved in the oxidizing agent.

The anchor-forming heat-resistant resin fine powder is, for example, agglomerated particles obtained by aggregating heat-resistant resin powder having an average particle size of 2 μm or less to an average particle size of 2 to 10 μm, and an average particle size of 2 to 10 μm. Heat-resistant resin powder and average particle size 2
A particle mixture with a heat resistant resin powder having a particle size of not more than μm, or a heat resistant resin powder having an average particle size of 2 to 10 μm has an average particle size of
It is desirable to select from pseudo particles formed by adhering at least one of a heat resistant resin fine powder having a particle size of not more than μm and an inorganic fine powder. The reason for this is that the use of such fine powder makes the shape of the anchor formed on the roughened surface of the adhesive layer complicated and prevents swelling during deposition of the electroless plating film.

When the heat-resistant resin fine powder for forming an anchor is formed on a base film having excellent releasability to obtain a film-like adhesive layer, it is preferable that the average particle size is small. 0.05 to 50 μm is desirable. The reason is that if the average particle size is smaller than 0.05 μm, the viscosity of the adhesive solution is likely to increase and the thixotropy also increases, so that it is difficult to obtain a uniform film. On the other hand, 50 μm
If it is larger, the density of the anchor formed by dissolution and removal is low, and the density tends to be non-uniform, so that the required adhesion strength and adhesion reliability cannot be obtained. Moreover, the unevenness of the surface of the adhesive layer becomes severe, so that the film thickness becomes non-uniform, which is disadvantageous in forming a fine pattern of the conductor and is not preferable in mounting the component.

As the curing agent for the resin matrix, an imidazole-based curing agent, especially 2 as shown in the chemical formula (1) is used.
-Phenylimidazole type curing agents are preferred. The reason for this is that the so-called pot life, which is the time from the kneading of the resin and the curing agent to the start of curing, is long, and that the epoxy resin cured with this curing agent has excellent electrical characteristics, moisture resistance, and chromium acid resistance. Is. Here, the symbols R ₁ ,
R ₂ represents one of an alkyl group, CH ₂ OH and H, and a methyl group, an ethyl group, a propyl group and a butyl group are preferable as the alkyl group.

[0031]

[Chemical 1]

The amount of this curing agent is preferably 2 to 10 wt% of the imidazole curing agent based on the total solid content of the resin matrix. The reason for this is that if it exceeds 10 wt%, it is too hard and becomes brittle, and if it is less than 2 wt%, sufficient heat resistance and resin strength cannot be obtained because the hardening is insufficient.

In addition, the heat-resistant resin fine powder which has been previously cured is
The mixture prepared by dispersing in the uncured epoxy resin matrix is stored separately from the imidazole-based curing agent, and the mixture of the two immediately before use can be used.
This is advantageous in preventing unnecessary dissolution of the curing agent in the solvent and controlling the dispersion state of the curing agent to be constant.

The wiring sheet adhesive sheet of the present invention is, for example, as shown in FIG. 1 (a), hardened heat-resistant resin fine powder is hardly soluble in acid or oxidant when subjected to a curing treatment. The adhesive solution dispersed in a resin matrix exhibiting the following characteristics is applied on a base film with a roll coater or doctor bar, and then dried in a drying oven set at 60 to 100 ° C to give a predetermined amount. It is obtained by removing the solvent and setting it in the B stage state. At this time, the thickness of the adhesive layer on the base film is adjusted to 15 to 150 μm by the doctor bar gap. Since this adhesive sheet is wound into a roll, a protective film (cover film) is formed on the adhesive layer to protect the uncured adhesive layer.

As the base film, polyethylene terephthalate, polypropylene and polyethylene fluoride (Tedlar film) films are preferably used. The thickness of this base film is 17-70μ
m is desirable. In addition, in order to prevent the adhesive from being repelled from the base film, the coated surface of the base film may be subjected to a mud treatment (unevenness treatment). In addition, in order to prevent dents or dents caused by foreign matter on the adhesive layer during contact between the sheets during the production of the adhesive sheet, mud treatment (concavo-convex treatment) is also applied to the opposite surface. Good. Furthermore, in order to facilitate peeling and removal of the base film,
Silicon may be applied as a release treatment to the contact surface with the adhesive layer.

Next, a method for manufacturing a printed wiring board using the adhesive sheet of the present invention and a printed wiring board will be described. First, stack the adhesive sheet on the substrate surface,
Then, lamination is performed under pressure and heating conditions. As the base material, glass epoxy, a metal substrate, a polyimide substrate, or the like can be used, and the surface of the base material may be roughened in advance. Next, when the adhesive sheet having the adhesive layer formed on the base film is used, the base film is peeled off, and then the adhesive layer is cured to form the adhesive layer on the base material. Then, the surface of the adhesive layer is roughened with an acid or an oxidizing agent, a plating resist is formed if necessary, and then electroless plating is performed to manufacture a printed wiring board. As the acid, hydrochloric acid, sulfuric acid, organic acid and the like are preferable, while as the oxidizing agent, chromic acid, ozone,
Preference is given to potassium permanganate and the like.

A printed wiring board using the adhesive sheet of the present invention produced in this manner is prepared, for example, by pre-curing heat-resistant resin fine powder soluble in an acid or an oxidant on a base material. An adhesive layer is provided which is hardened and dispersed in an epoxy resin matrix showing a property of being sparingly soluble in an acid or an oxidizing agent. A printed wiring board having a roughened surface that has been dissolved and removed with an agent, and a conductor circuit formed on the roughened surface, wherein the epoxy resin matrix having a molecular weight of 1000 or less is used. Is. A resist for electroless plating may be provided on the roughened surface of the adhesive layer of this printed wiring board.

As described above, according to the production method using the adhesive sheet of the present invention, the above-mentioned printing is simpler and less costly than the case where the adhesive composition is applied onto the substrate. A wiring board can be manufactured.

[0039]

(Example) (Example 1) (1) Bisphenol A type epoxy resin (made by Yuka Shell)
100 parts by weight was diluted with MEK, and a chain aliphatic polyamine (diethylenetriamine; manufactured by Sumitomo Chemical Co., Ltd.) was used as a curing agent.
After mixing by weight, the mixture was dried and cured at 100 ° C. for 2 hours. This cured epoxy resin is roughly crushed, and then, while being frozen in liquid nitrogen, finely crushed using a supersonic jet crusher (manufactured by Nippon Pneumatic Mfg. Co., Ltd.), and further into a wind classifier (manufactured by Donaldson Japan). And classify, average particle size 1.7 μm
The epoxy resin fine powder of was obtained. (2) 30 parts by weight of cresol novolac type epoxy resin (Nippon Kayaku, molecular weight 3600, mp = 90 ° C), 40 parts by weight of phenol novolac type epoxy resin (made by Yuka Shell, molecular weight 650, high viscosity liquid at room temperature) , 30 parts by weight of bisphenol A type epoxy resin (made by Yuka Shell, molecular weight 900, mp = 64 ° C.) and 5 parts by weight of imidazole type curing agent (made by Shikoku Kasei) were dissolved in methyl ethyl ketone to obtain a solid content of 10
The fine powder obtained in (1) above was mixed in an amount of 50 parts by weight with respect to 0 parts by weight, and methyl ethyl ketone was further added to adjust the solid content concentration to 60%, followed by kneading with a pearl mill. (3) Next, a leveling agent (made by San Nopco) is added to this kneaded product.
0.5 wt% was added and stirred with a homogenizer stirrer to prepare an adhesive solution. The viscosity of this solution is
It was 0.2 Pa · s at 60 rpm. (4) Application, drying (IR furnace), lamination (laminating)
And, using a roll coat laminator capable of winding, apply the adhesive solution 14 prepared in (3) above on the polypropylene film 6, and then dry it in an IR oven 7 at 100 ° C for 10 minutes. And further, polyethylene film 5 (protective film) at the roll laminator
And were laminated to produce an adhesive sheet (see FIG. 1 (a)). (5) The glass epoxy resin substrate 1 is roughened by polishing and JI
S-B0601 After forming a rough surface of R _max = 2 to 3 μm,
Polyethylene film 5 of the adhesive sheet created in (4)
Was peeled off, and this sheet was thermocompression bonded onto the roughened surface of the substrate 1 using a laminator under the conditions of a laminator temperature of 80 ° C., a pressure of 3.0 kgf / cm ² and a transfer speed of 50 cm / min (FIG. 1 (b)). reference). (6) Next, the polypropylene film 6 (base film) was peeled and removed, and then cured in a hot air drying oven at 120 ° C. for 3 hours and 150 ° C. for 5 hours to form an adhesive layer 2 (FIG. 1 ( See c)). (7) The substrate 1 on which the adhesive layer 2 has been formed is drilled with a drill and immersed in an oxidizing agent composed of an aqueous solution of chromic acid (CrO ₃ ) 500 g / l at 70 ° C. for 15 minutes to form the adhesive layer 2. After roughening the surface, it was immersed in a neutralizing solution (made by Shipley) and washed with water. A palladium catalyst (manufactured by Shipley) was applied to the substrate 1 having the roughened adhesive layer 2 to activate the surface of the adhesive layer 2 (see FIG. 1 (d)). (8) The substrate 1 is placed in a nitrogen gas atmosphere (10 ppm oxygen) 12
Heat treatment for catalyst immobilization was carried out at 0 ° C for 30 minutes, after which a photosensitive dry film was laminated, exposed to light, and then developed with modified chlorothane to obtain plating resist 3 (thickness
40 μm) was formed (see FIG. 1 (e)). (9) The substrate 1 on which the plating resist 3 has been formed is immersed in an electroless copper plating solution having the composition shown in Table 1 for 11 hours to apply electroless copper plating having a thickness of 25 μm to the plating film 4 and printed. A wiring board was manufactured (see Fig. 1 (f)).

[0040]

[Table 1]

As a result, no repellency was observed when the adhesive liquid was applied to the base film when preparing the adhesive sheet. Moreover, when the adhesive sheet was attached to the substrate at a conveying speed of 5 m / min, it was excellent in flexibility,
No cracks or fractures occurred in the adhesive layer. The peel strength of the electroless plating film is 2.2kg / cm (JIS-C-6481)
Therefore, the adhesiveness between the adhesive layer and the electroless plated film was excellent.

Example 2 (1) 1275 parts by weight of melamine resin, 1366 parts by weight of 37% formalin and 730 parts by weight of water were mixed, and pH was adjusted with 10% sodium carbonate.
After adjusting to 9.0 and holding at 90 ° C. for 60 minutes, 109 parts by weight of methanol was added. (2) This resin liquid was dried by a spray drying method to obtain a powdery resin. (3) The resin powder, the release agent, and the curing catalyst were crushed and mixed by a ball mill to obtain a mixed powder of the above resin. (4) Put the above mixed powder in a mold heated to 150 ℃,
A pressure of 250 kg / cm ² was applied and maintained for 60 minutes to obtain a molded body.
During the molding, the mold was opened for degassing. (5) The above molded product is crushed with a ball mill to give a particle size of 0.5 μm.
And 5.5 μm of heat resistant resin fine powder were obtained. (6) Next, 50 parts by weight of phenol novolac type epoxy resin (Nippon Kayaku: molecular weight 3600, mp = 90 ° C.), bisphenol A type epoxy resin (Okaka Shell: molecular weight 1600, mp
= 78 ° C) 30 parts by weight, bisphenol A type epoxy resin (made by Yuka Shell: molecular weight 380, liquid at room temperature, viscosity 120 poi
se) 20 parts by weight and 5 parts by weight of an imidazole type curing agent (manufactured by Shikoku Kasei) were dissolved in butyl cellosolve acetate to obtain a resin matrix composition. Then, with respect to 100 parts by weight of the solid content of this composition, 15 parts by weight of the fine powder prepared in (5) having a particle size of 0.5 μm and 30 parts by weight of a particle size of 5.5 μm are ball milled. , And then add butyl cellosolve acetate to obtain a solid content of 60%.
An adhesive solution of was prepared. The viscosity of this solution is JIS K711
According to 7, measured with a digital viscometer (DVL-B) manufactured by Tokyo Keiki at 20 ° C for 60 seconds, 0.2 Pa · s at 60 rpm
Met. (7) This adhesive solution was applied onto a PET (polyethylene terephthalate) film 6 having a silicon coating on its surface with a doctor blade 8 and dried in an IR oven 7 at 80 ° C. for 5 minutes to be in a B stage state. A polyethylene cover film 5 (to protect the surface of the adhesive) was attached to form an adhesive sheet (see FIG. 2 (a)). As a result of measuring the residual solvent ratio in the same manner as in Example 1, it was 2% by weight. (8) Next, both surfaces of the glass epoxy substrate 1 are roughened by polishing to form a rough surface of 2 to 3 μm, and then the adhesive sheet prepared in (7) is superposed on the roughened surface of the substrate. ,
It was heated under pressure at 80 ° C., 3 kg / cm ² , and 5 m / min (see FIGS. 2 (b) and 2 (c)). (9) The substrate 1 with an adhesive sheet, which has been subjected to the process of (8) above,
Chromic acid (CrO ₃ ) is used as an oxidizing agent consisting of 500 g / l aqueous solution.
After dipping for 15 minutes at ℃ to roughen the surface of the adhesive layer 2,
It was immersed in a neutralizing solution (made by Shipley) and washed with water. Noble metal ultrafine particle sol (manufactured by Toda Kogyo) was applied to the substrate 1 having the roughened adhesive layer 2 to activate the surface of the insulating layer 2 (see FIG. 2 (d)). (10) The substrate 1 is placed in a nitrogen gas atmosphere (10 ppm oxygen) 12
Heat treatment for catalyst immobilization was performed at 0 ° C. for 30 minutes. After that, a photosensitive dry film was laminated, exposed, and then developed with an aqueous sodium carbonate solution to form a plating resist 3 (thickness 40 μm) (see FIG. 2 (e)). After that, UV irradiation of ³ J / cm ² and heat treatment at 150 ° C / 30 minutes are performed.
The resist was completely cured. (11) Further, the substrate 1 that has been subjected to the treatment of (10) is immersed in an electroless copper plating solution having the composition shown in Table 1 for 11 hours to form a plated film 4
25 μm thick electroless copper plating was applied to produce a printed wiring board (see FIG. 2 (f)).

As a result, when the adhesive sheet was prepared, no repellency was observed even when the adhesive liquid was applied to the base film. Moreover, when the adhesive sheet was attached to the substrate at a conveying speed of 5 m / min, it was excellent in flexibility,
No cracks or fractures occurred in the adhesive layer. The peel strength of the electroless plating film is 2.1kg / cm (JIS-C-6481)
Therefore, the adhesiveness between the adhesive layer and the electroless plated film was excellent.

Example 3 (1) 10 parts by weight of cresol novolac type epoxy resin (Nippon Kayaku, molecular weight 3600, melting point 90 ° C.), phenol novolac type epoxy resin (Okaka Shell, molecular weight 650, high at room temperature) 50 parts by weight of viscous liquid and brominated modified bisphenol A type epoxy resin (Mitsui Petrochemical, molecular weight 1100,
40 parts by weight (melting point: 74 ° C.) was dissolved in MEK to obtain a resin liquid. (2) 30 parts by weight of MEK was added to 10 parts by weight of an epoxy resin fine powder (particle size 0.5 μm) and dispersed by ultrasonic waves to obtain a suspension. (3) To the suspension obtained in (2) above, add the resin solution obtained in (1) in 5 times, and add 0.5 mm / min to a sand mill filled with 2 mm zirconia balls every time the resin solution is added. Mixed at flow rate. (4) To the mixed resin liquid prepared in the above (3), 25 parts by weight of an epoxy resin fine powder (particle size 5 μm) and 5 parts by weight of an imidazole curing accelerator were added and further mixed by a sand mill. (5) To 100 parts by weight of the mixed resin liquid prepared in (4) above, 0.2 parts by weight of a leveling agent and 0.3 parts by weight of a defoaming agent were added, and then mixed with a homodisper stirrer to obtain a solid content concentration of 70
%, An adhesive solution having a viscosity of 0.30 Pa · S at 6 rpm and a thixotropic property of 5.0 was prepared. (6) The adhesive solution prepared in (5) above was applied to a mud-treated polypropylene film 6 having a thickness of 40 μm by a doctor blade 8 and then heated at 80 ° C. in a hot air circulation oven at 80 ° C.
After drying for 5 minutes, an adhesive layer 2 having a thickness of 40 μm and a residual solvent ratio of 1.5% was formed. (7) A polyethylene film 5 was further thermocompression-bonded onto the adhesive layer 2 formed in (6) above to prepare an adhesive sheet having a three-layer structure. (8) Next, the surface of the glass epoxy substrate 1 is roughened by polishing to form a rough surface of 3 μm, and then the substrate 1 is preheated to a surface temperature of 60 ° C. While peeling off the polyethylene film 5 of the adhesive sheet prepared in 1. above, the adhesive layer 2 was superposed on the substrate side and thermocompression-bonded at the same time at 80 ° C. and a conveying speed of 5 m / min. (9) After peeling off the polypropylene film 6 on the surface, the adhesive layer 2 was cured by heat treatment at 120 ° C. for 2 hours and at 150 ° C. for 1 hour. The Tg point of this adhesive layer 2 was 170 ° C. as observed by a viscoelasticity spectrometer. (10) Substrate 1 with an adhesive sheet that has undergone the treatment of (9) above
At 70 ° C with an oxidizing agent consisting of an aqueous solution of 800 g / l chromic anhydride (CrO ₃ ) in which the proportion of Cr ^{3+ in} the total Cr is 0.50%.
The surface of the adhesive layer 2 was roughened by immersion for 20 minutes. The obtained surface had a surface roughness R _Z = 12 μm and _Ra = 2.0 μm. (11) Next, the roughened surface is washed with water, and sodium sulfite 400
It was immersed in an aqueous solution of g / l for 20 minutes at room temperature to neutralize Cr ⁶⁺ . After that, rinse with hot water at 70 ℃ for 20 minutes, then rinse with water for 80 minutes.
It was dried at 0 ° C for 10 minutes. (12) The substrate 1 that had been subjected to the treatment of (11) above was perforated by a conventional method, and then the through holes were washed by washing with high pressure water of 5 kg / cm ² . (13) Then, the substrate 1 was degreased by a conventional method, and after hydrophilization treatment with a surfactant and acid treatment, Sn colloid catalyst of Pd was added and acid treatment was carried out again to remove unnecessary Sn.
At this time, the amount of Pd adsorbed on the surface was 5 μg / cm ² . (14) The substrate 1 which has been subjected to the treatment of (13) is heat-treated at 120 ° C. for 40 minutes to fix the catalyst nuclei on the surface and then preheated to 80 ° C., and then the dry film plating resist is heated to 100 ° C.
Then, the plating resist 3 was formed by performing thermocompression bonding and exposing, developing, UV curing, and heat treatment by a conventional method. (15) Then, after activating the catalyst by acid treatment, electroless copper plating with a thickness of 25 μm of the plated film 4 was performed by a conventional method. At this time, the step difference between the plating resist and the conductor pattern formed by the plating film was 5 μm. (16) Furthermore, a solder resist is formed by a conventional method,
It was solder-coated and used as a wiring board.

As a result, when the adhesive sheet was prepared, no repellency was observed even when the adhesive liquid was applied to the base film. The peel strength of the electroless plated film was 2.1 kg / cm (JIS-C-6481), and the adhesiveness between the adhesive layer and the electroless plated film was excellent.

Comparative Example 1 Basically the same as in Example 1, except that 60 parts by weight of cresol novolac type epoxy resin (molecular weight 360) and 40 parts by weight of bisphenol A type epoxy resin (molecular weight 900) were used as matrix resins. used. As a result, when the adhesive is processed into a film, not only edge fusion is likely to occur due to the large fluidity of the resin, but also when the adhesive sheet is tried to be attached to the substrate at a conveying speed of 1 m / min, Since the tackiness of the resin was great, the polyethylene used as the protective film was not peeled off and could not be laminated.

Comparative Example 2 Basically the same as in Example 1, but as the matrix resin, cresol novolac type epoxy resin (Nippon Kayaku, molecular weight 3600, melting point 90 ° C.)
100 parts by weight were used. As a result, 5m adhesive sheet
When it was applied to the substrate at a transportation speed of / minute, the adhesive layer was broken.

Comparative Example 3 Basically the same as in Example 1, except that the drying time of the adhesive sheet was shortened and the residual solvent ratio of the adhesive sheet was set to 5 wt%. As a result, when the adhesive sheet was attached to the substrate at a conveying speed of 5 m / min, not only was the peelability of the polyethylene used as the protective film poor, but the resin adhered to the blade used to cut the sheet, resulting in cutting properties. Has the drawback of being worse. further,
When the electroless plating was applied after roughening the adhesive layer provided on the substrate, the peel strength of the electroless plating film was 1.6 kg /
It fell to cm. The reason for this is considered to be that the residual solvent ratio was too high and the hardening rate of the matrix was lowered, and therefore the strength and the acid resistance to chromium were lowered.

Comparative Example 4 Basically the same as in Example 1, except that the drying time of the sheet was shortened and the residual solvent ratio of the sheet was 0.3 wt%. As a result, the adhesive sheet
When it was attached to the substrate at a conveying speed of minutes, the adhesive layer was broken.

[0050]

As described above, according to the present invention, by controlling the molecular weight distribution of the epoxy resin matrix and the residual solvent ratio of the adhesive layer, chemical resistance, heat resistance, electrical characteristics and electroless plating film can be obtained. It is possible to provide an adhesive sheet having excellent flexibility without impairing the adhesiveness with, and therefore, it is possible to effectively improve the productivity of the printed wiring board.

[Brief description of drawings]

FIG. 1 is a manufacturing process drawing of a printed wiring board using the adhesive sheet of the present invention.

FIG. 2 is another manufacturing process diagram of a printed wiring board using the adhesive sheet of the present invention.

[Explanation of symbols]

 1 Substrate 2 Adhesive Layer 3 Plating Resist 4 Plating Film (Conductor Layer) 5 Polyethylene Film 6 Polypropylene Film, PET Film 7 Drying Furnace (IR Furnace) 8 Doctor Blade

Claims (1)

[Claims] 1. An uncured epoxy resin exhibiting a property that a heat-curable resin fine powder that is soluble in an acid or an oxidizing agent and is hardened in advance is hardly soluble in an acid or an oxidizing agent when subjected to a curing treatment. Dispersed in a matrix,
An adhesive sheet formed by forming an adhesive into a sheet, wherein the epoxy resin matrix contains at least 20 to 80 wt% of a resin having a molecular weight of 1000 or less, and the amount of solvent remaining in the adhesive layer is 0.5 to 3.0. An adhesive sheet for a wiring board, which is characterized by using wt%.