JPH06158333A - Adhesive and printed circuit board - Google Patents

Abstract

PURPOSE:To almost prevent the cracking of the adhesive layer of a printed circuit board and the peeling of the plating even in a cryogenic cycle test by using an adhesive contg. heat resistant fine powder having thermal expansion characteristics close to those of a metal for plating. CONSTITUTION:Inorg. powder is coated with epoxy resin and pulverized to form heat resistant fine powder having <=3mum average particle diameter and 60 pts.wt. phenol-novolak type epoxy resin, 40 pts.wt. bisphenol A type epoxy resin, 4 pts.wt. imidazole curing agent and butyl cellosolve as a solvent are added to 50 pts.wt. of the fine powder. They are kneaded to prepare an adhesive soln. and this soln. is applied to a glass-epoxy substrate and dried to form an adhesive layer having 20mum thickness. The surface of this adhesive layer is activated, subjected to electroless Cu plating in 25mum thickness and further subjected to Cu electroplating in 35mum thickness in a copper sulfate plating bath to obtain the objective printed circuit board.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an adhesive used for electroless plating, and a printed wiring board using this adhesive, and particularly to a low thermal expansion coefficient and an electroless plated film. We propose an electroless plating adhesive suitable as an adhesive layer having excellent adhesion, and a highly reliable printed wiring board using this adhesive.

[0002]

2. Description of the Related Art In recent years, with the progress of the electronic industry, electronic devices have been reduced in size and increased in speed. For this reason, a printed circuit board and a wiring board on which an LSI is mounted have a high density and a fine pattern. High reliability is required.

Conventionally, as a method for forming a conductor circuit on a printed wiring board, an etched foil method for forming a conductor circuit by laminating a copper foil on a substrate and then photoetching has been widely used. According to this method, it is possible to form a conductor circuit having excellent adhesion to the substrate, but the cost is high, and it is difficult to obtain a highly precise fine pattern by etching because the copper foil is thick. In addition, there is a problem that the manufacturing process is complicated and the efficiency is low.

Therefore, recently, as a method of forming a conductor on a wiring board, an adhesive containing diene-based synthetic rubber was applied to the substrate surface to form an adhesive layer, and the surface of the adhesive layer was roughened. After that, an additive method of applying electroless plating to form a conductor is adopted. However, since the adhesive used under this method contains synthetic rubber, it has a low heat resistance such as a large decrease in adhesion strength at high temperature, or a swelling of the electroless plating film during soldering, There are problems such as insufficient electrical properties such as surface resistance, and the range of use is considerably limited.

On the other hand, the present inventors previously solved the above-mentioned drawbacks of the adhesive for applying electroless plating, and were excellent in heat resistance, electric characteristics and adhesion to the electroless plated film. In addition, an adhesive which is relatively easy to carry out and a method for manufacturing a wiring board using this adhesive have been proposed (Japanese Patent Laid-Open No. Sho 61-61).
-276875 gazette). That is, the conventional technique proposed by the inventors is such that an uncured resin powder having a property that a pre-cured heat-resistant resin powder that is soluble in an oxidant is hardly soluble in the oxidant when subjected to a curing treatment. Of the heat-resistant resin liquid, and after applying the adhesive to a substrate, it is dried and cured to form an adhesive layer, and the above-mentioned fine particles dispersed on the surface portion of the adhesive layer. In this method, at least a part of the powder is dissolved and removed to roughen the surface of the adhesive layer, and then electroless plating is performed.

According to this prior art, in the above-mentioned adhesive, the heat-resistant resin fine powder which has been preliminarily 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 adhesive layer. Since the heat-resistant resin fine powder and the heat-resistant resin matrix 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. As a result, uniform anchor depressions are formed on the surface of the adhesive layer, and the adhesiveness between the adhesive layer and the electroless plating film is improved.

[0007]

By the way, the above-mentioned adhesives proposed by the present inventors are general-purpose and easily available as hardened heat-resistant resin fine powder which is soluble in acid or oxidizing agent, and , Epoxy resin fine powder, which is a resin with excellent chemical resistance, heat resistance, electrical characteristics and hardness, has been used.

However, the adhesive layer made of the above-mentioned adhesive using a resin simple substance as the heat resistant fine powder has a higher coefficient of thermal expansion than the electroless plated film. Therefore, when a printed wiring board having a conductor circuit formed by applying a plating film on this adhesive layer is subjected to a thermal cycle test, cracks may occur in the adhesive layer, and the plating film is likely to peel off, which is an unsolved problem. It turns out that there is.

Further, since the resin fine powder dispersed therein is soluble in an acid or an oxidizing agent (roughening liquid), the adhesive layer composed of the above-mentioned adhesive using a resin simple substance as the heat resistant fine powder, There is also a problem that the amount of resin eluted during anchor formation is increased, which promotes deterioration of acid and oxidizing agent (roughening liquid) (decrease in oxidizing power).

An object of the present invention is to overcome the above problems of the prior art, and in particular, it has a coefficient of thermal expansion similar to that of an electroless plating film and is in an environment such as a thermal cycle test. Another object of the present invention is to provide an adhesive having excellent adhesion to an electroless plating film, and a printed wiring board using this adhesive.

[0011]

[Means for Solving the Problems] In order to achieve the above-mentioned object, the inventors of the present invention have conducted extensive studies focusing mainly on the heat-resistant fine powder in the adhesive, and as a result, have found that the anchor forming ability is excellent and the plating metal is As a heat-resistant fine powder showing similar thermal expansion characteristics, it was found that an inorganic powder coated with a heat-resistant resin soluble in an acid or an oxidant is effective.
The present invention was conceived.

That is, a feature of the present invention is that the heat-resistant fine powder is dispersed in an uncured heat-resistant resin matrix which exhibits a property of being hardly soluble in an acid or an oxidizing agent when subjected to a curing treatment. In the adhesive obtained, as the heat resistant fine powder, an inorganic powder coated with a cured heat resistant resin that is soluble in an acid or an oxidizing agent is used. It is preferably provided in the form of a sheet or a prepreg.

The printed wiring board of the present invention is characterized in that the above-mentioned adhesive is used. The gist of the printed wiring board is to cure heat-resistant fine powder on at least one substrate surface. An adhesive layer, which is dispersed in an uncured heat-resistant resin matrix that exhibits a property of being sparingly soluble in an acid or an oxidant when treated, is applied to form an adhesive layer on which a conductor circuit is formed. In the printed wiring board provided with, the heat resistant fine powder is obtained by coating the heat resistant fine powder of an inorganic powder with a heat resistant resin that is soluble in an acid or an oxidant.

[0014]

According to the adhesive of the present invention, the coefficient of thermal expansion of the heat-resistant fine powder obtained by coating the resin with the inorganic powder dispersed in the resin matrix is higher than that of the heat-resistant fine powder made of the organic resin alone. It was found that the thermal expansion characteristics were almost the same as those of the plated metal. Therefore, the adhesive layer in which the heat-resistant fine powder is dispersed in a predetermined amount exhibits a thermal expansion coefficient similar to that of the electroless plating film. As a result, even when the thermal cycle test of the printed wiring board is performed, the difference in shrinkage or difference in expansion of the adhesive layer that occurs during rapid heating and rapid cooling becomes small, and cracking of the adhesive layer and peeling of the plating film do not occur easily. .

Further, since the electroless plating is carried out in a high temperature range, in the case of an adhesive in which heat resistant fine powder made of a simple resin is dispersed, the electroless plating is performed on the adhesive layer in a thermally expanded state. Will be applied to. As a result, during cooling of the electroless plating, breakage between the electroless plating layer and the adhesive layer is likely to occur. In this respect, according to the adhesive of the present invention, since the heat-resistant fine powder in which the inorganic powder is coated with the resin is dispersed, the adhesive layer using such an adhesive has a thermal expansion coefficient with the electroless plating film. The difference can be reduced, and consequently, the above-mentioned destruction due to the difference in thermal expansion hardly occurs.

Further, in roughening the surface of the adhesive layer, the heat-resistant resin film constituting the heat-resistant fine powder of the present invention is soluble in the roughening liquid, while the inorganic powder is insoluble in the roughening liquid. Therefore, in the heat-resistant fine powder, only the heat-resistant resin film is dissolved to become the inorganic fine powder, which easily falls off from the adhesive layer.
From this, according to the adhesive of the present invention, the amount of resin to be dissolved and removed is significantly reduced as compared with the prior art in which the heat-resistant fine powder made of a resin alone is dissolved and removed to form the anchor. The anchor formation becomes easy. Moreover, since the amount of resin eluted into the roughening liquid is reduced, deterioration of the roughening liquid can be suppressed, and the life of the roughening liquid can be significantly improved.

Regarding the adhesive according to the present invention,
By providing in sheet or prepreg form,
The printed wiring board can be easily and inexpensively obtained without impairing the electroless plating property.

As described above, the effect of applying the adhesive of the present invention to a wiring board has been described.
It is also applicable in other fields.

In the adhesive of the present invention, the above-mentioned heat-resistant fine powder obtained by coating an inorganic powder with a heat-resistant resin has a low coefficient of thermal expansion, is excellent in heat resistance and electric insulation, and is resistant to ordinary chemicals. It is required to be stable. To this end, the heat-resistant resin coating the inorganic powder is hardly soluble in the heat-resistant resin liquid that constitutes the matrix or the solvent that dissolves this resin when it is cured, and is easily soluble in the chromic acid oxidizing agent. From the necessity of being a resin having the following characteristics, amino resins and epoxy resins are preferable, and among them, epoxy resins and melamine resins cured with an amine-based curing agent are the most preferable because they have excellent characteristics. In addition, the inorganic powder is preferably alumina, silica, zirconia, or the like, and silica is particularly preferable because of its low coefficient of thermal expansion and electrical insulation. Further, the heat resistant resin needs to be previously cured. The reason for this is that if the adhesive is not cured, it will dissolve if the adhesive is diluted with a solvent such as methyl ethyl ketone described later.

The heat-resistant fine powder obtained by coating the inorganic powder with a heat-resistant resin is, for example, a wet process of immersing the inorganic powder in a heat-resistant resin solution to adhere the resin to the surface of the inorganic powder, and then the adhesion. The lumps formed by curing the resin are crushed and classified as necessary, while the inorganic powder and the heat-resistant resin fine powder are dispersed in the gas phase, the mechanical heat mainly caused by impact force is applied to these powders. The heat-resistant resin fine powder is adhered to the surface of the inorganic powder by a dry process that imparts specific energy, and then the adhered resin is heated and cured to form a film.

Here, the ratio of the inorganic powder to the heat resistant resin is preferably a volume ratio, and the ratio of the inorganic powder to the fine powder obtained by coating the inorganic powder with the heat resistant resin is 10 to 90%. The reason for this is that if the proportion of the inorganic component is more than 90%, it will not dissolve well and a clear anchor will not be formed. On the other hand, if the proportion of the inorganic component is less than 10%, the effect of reducing the thermal expansion coefficient of the adhesive by the inorganic powder cannot be sufficiently obtained.

The shape of the heat-resistant fine powder thus obtained is not only spherical but also various complicated shapes as shown in FIGS. 1 (a) to 1 (d). ) Shape,
The larger the volume ratio, the more desirable. The reason for this is that not only is the inorganic content high and the effect of lowering the coefficient of thermal expansion large, but also the formation of anchors is easy. The inorganic powder needs to be coated with a heat-resistant resin film that is soluble in at least an acid or an oxidizing agent.

The heat-resistant fine powder prepared as described above has a solid content of 10 to 10 with respect to the heat-resistant resin matrix.
It is desirable to mix 100 parts by weight. The reason for this is that if the amount of the fine powder blended is less than 10 parts by weight, the coefficient of thermal expansion is low and the anchor formed by dissolution and removal is not clearly formed. On the other hand, the amount of fine powder is 100
If the amount is more than the weight part, the coefficient of thermal expansion of the adhesive layer can be improved to the same level as that of the electroless plating layer, but since the adhesive layer surface becomes porous, the adhesion between the adhesive layer and the electroless plating film This is because the strength (peel strength) is reduced.

The particle size of such heat-resistant fine powder is
The average particle size is preferably 10 μm or less, especially 5 μm
It is preferably m or less. The reason for this is that if the average particle size is larger than 10 μm, the density of the anchors formed by dissolution and removal will be low, and it tends to be non-uniform,
Adhesion strength and its reliability decrease. Moreover, since the unevenness of the surface of the adhesive layer becomes severe, it is difficult to obtain a fine pattern of the conductor, and it is not preferable for mounting components and the like.

Next, the heat-resistant resin matrix in which the heat-resistant fine powder is dispersed has excellent heat resistance, electrical insulation, chemical stability and adhesiveness, and is hardly soluble in an oxidizer when cured. Resins exhibiting the following characteristics can be used. Above all, a thermosetting heat-resistant resin, which is either an uncured polyfunctional epoxy resin or an uncured difunctional epoxy resin, is used, and the solid content is 20 to 100 wt%.
It is preferred to use a mixture of the uncured polyfunctional epoxy resin of 0 to 80 wt% of the uncured difunctional epoxy resin. The reason for this is that if the solid content of the uncured polyfunctional epoxy resin is less than 20 wt%, the hardness of the adhesive will be reduced and the chemical resistance will be reduced.

The heat resistant resin matrix may be a photosensitive resin. In particular, at least one photosensitive heat-resistant resin selected from uncured polyfunctional epoxy resin, uncured polyfunctional acrylic group-containing resin, and uncured polyfunctional acrylic resin, or these resins And uncured bifunctional epoxy resin,
It is also possible to use a resin composed of a mixed resin with at least one photosensitive heat-resistant resin selected from an uncured bifunctional acrylic resin. The composition of the resin is solid content,
20 to 100 wt% of uncured polyfunctional epoxy resin,
At least one photosensitive heat-resistant resin selected from uncured polyfunctional acrylic group-containing resin and uncured polyfunctional acrylic resin, and 0 to 80 wt% of uncured 2
It is preferable to use a mixed resin of a functional epoxy resin and at least one photosensitive heat-resistant resin selected from an uncured bifunctional acrylic resin.

As the curing agent for the heat-resistant resin matrix, DICY, amine curing agents, acid anhydrides, imidazole curing agents and the like can be used. In particular, when the heat-resistant resin matrix is an epoxy resin, it is preferable to contain an imidazole-based curing agent in a solid content of 2 to 10 wt%. The reason is that if it exceeds 10 wt%, it is too hard and becomes brittle, and if it is less than 2 wt%, the hardening becomes insufficient and sufficient resin strength cannot be obtained.

When the above imidazole-based curing agent is used, in particular, the heat-resistant fine powder is dispersed in a thermosetting heat-resistant resin matrix which is either an uncured polyfunctional epoxy resin or a bifunctional epoxy resin. When applied to an adhesive that is made to stand, the imidazole-based curing agent and the adhesive are separately stored, and by mixing and using them immediately before use, pot life (usable time ) Is desirable.

Further, this heat resistant resin matrix is
Although a heat-resistant resin containing no solvent can be used as it is, it is preferably used in the state of a heat-resistant resin liquid prepared by dissolving this heat-resistant resin in a solvent. The reason for this is that the resin liquid makes it easier to adjust the viscosity, allows the fine powder to be uniformly dispersed, and is easier to apply to the substrate. As a solvent used for dissolving the heat resistant resin, 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 is suitable. Is.

Further, in the heat resistant resin matrix, for example, an organic filler such as a fluororesin, a polyimide resin, a benzoguanamine resin, or a filler made of an inorganic fine powder such as silica, alumina, titanium oxide or zirconia is appropriately used. It may be blended, or additives such as a colorant (pigment), a leveling agent, an antifoaming agent, an ultraviolet absorber and a flame retardant may be blended and added.

Next, a method for manufacturing a printed wiring board using the above adhesive of the present invention will be described. In the production of a printed wiring board using the adhesive of the present invention, first, the adhesive obtained by dispersing heat-resistant fine powder in a heat-resistant resin matrix is applied onto a substrate using a roll coater or the like. After that, it is dried and cured to form an adhesive layer. The adhesive layer can also be formed by sticking an adhesive formed into a sheet shape or a prepreg shape onto a substrate. The thickness of this adhesive layer is usually about 20 to 70 μm, but when this adhesive layer is also used as an interlayer insulating layer of a metal substrate or a multilayer wiring board,
It can also be applied thicker than that.

As the substrate, for example, a plastic substrate, a ceramic substrate, a metal substrate, a film substrate or the like can be used. For example, a glass epoxy substrate, a glass polyimide substrate, an alumina substrate, a low temperature fired ceramic substrate, an aluminum nitride substrate, an aluminum substrate, an iron substrate and a polyimide film substrate.
Then, using these substrates, a single-sided wiring board, a double-sided through-hole wiring board, and a multilayer wiring board such as a Cu / polyimide multilayer wiring board are manufactured. It is also possible to form the adhesive itself into a plate shape or a film shape and use it as a base material having adhesiveness that can be subjected to electroless plating.

The next step is a treatment in which at least a part of the heat-resistant fine powder dispersed on the surface of the adhesive layer provided on the substrate as described above is dissolved and removed using an acid or an oxidizing agent. is there. This dissolution removal treatment is performed by immersing the substrate on which the adhesive layer is formed in the solution of the acid or oxidizing agent, or by spraying the substrate with the acid or oxidizing agent solution. By this treatment, the surface of the adhesive layer becomes a roughened surface suitable for plating. Here, the oxidizing agent for roughening the adhesive layer is preferably chromic acid, chromate salt, permanganate, ozone or the like, and the acid is preferably hydrochloric acid, sulfuric acid, organic acid or the like. For the purpose of effectively dissolving and removing the heat-resistant fine powder, the surface portion of the adhesive layer is lightly roughened in advance by polishing or liquid honing with a fine powder abrasive, for example. Is extremely effective.

Next, the surface of the roughened adhesive layer is subjected to electroless plating to form a necessary conductor pattern, and a desired printed wiring board is obtained. As this electroless plating, for example, electroless copper plating, electroless nickel plating, electroless tin plating, electroless gold plating, electroless silver plating, etc. can be applied, in particular electroless copper plating, electroless nickel plating and electroless plating. It is preferable to use at least one method of gold plating. In the method for manufacturing the printed wiring board, after applying the electroless plating,
Furthermore, different types of electroless plating or electroplating can be performed, or solder can be coated.

Further, in the above method, the conductor circuit can be formed by various methods which have been carried out for known printed wiring boards. For example,
A method of etching a circuit after applying electroless plating to the substrate or a method of directly forming a circuit when applying electroless plating may be applied.

Next, the printed wiring board of the present invention obtained as described above will be described. The printed wiring board of the present invention is a single-sided printed wiring board formed by forming a plating resist and a conductor circuit on the substrate via the adhesive layer, and forming a conductor circuit via the adhesive layer and through holes on both sides of the substrate. A double-sided through-hole printed wiring board and a build-up multilayer wiring board in which conductor circuits are formed in multiple layers on a substrate on which a first conductor layer is formed with an interlayer insulating layer (adhesive layer) having via holes In the above, the adhesive layer, for any wiring board, has a heat-resistant fine powder dispersed in a heat-resistant resin matrix showing a property of being hardly soluble in an acid or an oxidant when cured. In addition, the heat-resistant fine powder is formed by coating the inorganic powder with a hardened heat-resistant resin that is soluble in acid or oxidant. It is characterized in that.

[0037]

【Example】

(Example 1) (1) 8 parts by weight of a diethylenetriamine curing agent was added to an epoxy resin (made by Yuka Shell Co., Ltd.), and further methyl ethyl ketone was added thereto to prepare an epoxy resin solution having a solid content of about 20%. Prepared. (2) Next, by adding inorganic powder (manufactured by Nippon Shokubai Kagaku Kogyo; SiO ₂ spheres 1.5 μmφ) to this epoxy resin liquid and stirring it, the epoxy resin liquid is attached to the surface of the inorganic powder, and then this inorganic resin Remove the powder and dry at 80 ° C for 20 minutes,
Then, the mixture was heated and cured at 100 ° C. for 1 hour and 130 ° C. for 2 hours to obtain a lump in which the inorganic powder was coated with an epoxy resin. (3) Then, using a ball mill, rotate the mass 20 times.
Coarse pulverization at 00 rpm, and further alumina balls (5 mmφ)
Was finely pulverized to obtain heat resistant fine powder having an average particle diameter of 3 μmφ. (4) 60 parts by weight of phenol novolac type epoxy resin (made by Yuka Shell), 40 parts by weight of bisphenol A type epoxy resin (made by Yuka Shell), 4 parts by weight of imidazole curing agent (made by Shikoku Kasei) and the above (1) ~ 50 parts by weight of the heat-resistant fine powder prepared in (3), while adding the butyl cellosolve solvent, adjust the viscosity to 120 cps with a homodispers disperser, then knead with a three-roll to obtain an adhesive solution. It was (5) After applying the adhesive solution obtained in (4) above to a glass epoxy substrate (made by Hitachi Chemical Co., Ltd.) on which a copper foil is not attached, using a roller coater, at 100 ° C. for 1 hour,
Further, it was dried and cured at 150 ° C. for 5 hours to form an adhesive layer having a thickness of 20 μm. (6) Chromic acid (CrO ₃ ) 500 g was added to the substrate obtained in (5) above.
The surface of the adhesive layer was roughened by immersing it in an oxidizing agent consisting of an aqueous solution of 1 / l at 70 ° C. for 15 minutes, and then immersing it in a neutralizing solution (manufactured by Shipley) and washing with water. (7) The surface of the adhesive layer obtained in (6) above is roughened, and a palladium catalyst (manufactured by Shipley Co.) is applied to activate the surface of the adhesive layer. The film was immersed in an electroless plating solution for additive method for 11 hours to perform electroless copper plating with a plating film thickness of 25 μm. Copper sulfate (CuSO ₄ .5H ₂ O): 0.06 mol / l formalin (37%): 0.30 mol / l sodium hydroxide: 0.35 mol / l EDTA: 0.12 mol / l Additives: a little Plating temperature: 70 to 72 ° C pH: 12.4 (8) The wiring board produced as described above was further electroplated with copper to a thickness of 35 μm in a copper sulfate plating bath.

(Example 2) (1) Epoxy resin-based fine powder (made by Yuka Shell) and inorganic fine powder (silica) were used in a surface reformer "Hybridization System" manufactured by Nara Machinery Co., Ltd. Then, a heat resistant fine powder in which the surface of the inorganic fine powder was coated with an epoxy resin was obtained. This system consists of dispersing inorganic powder and fine powder of heat-resistant resin in the gas phase, and applying dry mechanical treatment to these powders to impart mechanical and thermal energy mainly to the impact force. Fine powder is adhered, and then the adhered resin is heat-cured to form a film. (2) Next, using the heat-resistant fine powder obtained in the above (1),
A printed wiring board was manufactured in the same manner as in Example 1.

A printed wiring board manufactured by using the heat-resistant fine powder obtained by variously changing the volume ratio of the inorganic powder to the fine powder obtained by coating the inorganic powder with the heat-resistant resin in Examples 1 and 2 described above, Adhesion strength (peeling strength, JIS-C-6481) between the substrate and the copper plating film, adhesive, under comparison with a printed wiring board manufactured using heat resistant fine powder consisting of organic resin alone or inorganic powder alone The coefficient of thermal expansion of the layer and the state after the thermal cycling test were evaluated.

That is, the anchor forming ability is evaluated by measuring the peel strength of the printed wiring board, and further the thermal cycle test of the printed wiring board is carried out, whereby the coefficient of thermal expansion of the adhesive layer is evaluated as the reliability of the printed wiring board. The effect on the The results are shown in Table 1.

[0041]

[Table 1]

Example 3 (1) To an epoxy resin (made by Yuka Shell Co., Ltd.), 8 parts by weight of an ethylenediamine curing agent was added, and further methyl ethyl ketone was added to the epoxy resin to give an epoxy resin having a solid content of about 20%. A resin solution was prepared. (2) Next, add the inorganic fine powder (alumina) to the epoxy resin liquid.
0.1-0.5 μmφ) 50 parts by weight is added and stirred to attach the epoxy resin solution to the surface of the inorganic powder,
A thin film of 10 μmt was formed, and then this inorganic powder was taken out and dried at 80 ° C. for 20 minutes, and then at 100 ° C. for 1 hour.
It was heat-cured at 130 ° C. for 3 hours to obtain a lump in which an inorganic powder was coated with an epoxy resin. (3) Then, this lump is roughly crushed, and further, using a ball mill, the number of revolutions is 60 rpm with alumina balls (5 mmφ).
Was finely pulverized to obtain heat resistant fine powder having an average particle diameter of 3 μmφ. (4) Next, a printed wiring board was manufactured in the same manner as in Example 1 using the heat-resistant fine powder obtained in (1) to (3) above.

In the above-described Example 3, a printed wiring board manufactured using heat-resistant fine powder obtained by variously changing the volume ratio of the inorganic powder to the fine powder obtained by coating the inorganic powder with the heat-resistant resin Based on a comparison with a printed wiring board manufactured using a heat-resistant fine powder consisting of a single substance or a single inorganic powder, the adhesion strength (peeling strength, JIS-C-6481) between the substrate and the copper plating film, the adhesive layer The coefficient of thermal expansion and the state after the thermal cycle test were evaluated. The results are shown in Table 2.

[0044]

[Table 2]

Example 4 (1) To an epoxy resin (made by Yuka Shell Co., Ltd.), 8 parts by weight of an ethylenetriamine curing agent was added, and further methyl ethyl ketone was added to the epoxy resin to give a solid content of about 20%. An epoxy resin solution was prepared. (2) Next, inorganic fine powder (silica pulverized product; non-spherical, average particle size 1 to 3 μmφ) is added to this epoxy resin liquid and stirred to attach the epoxy resin liquid to the surface of the inorganic powder, and then The inorganic powder was taken out and dried at 80 ° C. for 20 minutes, and then heat-cured at 100 ° C. for 1 hour and 130 ° C. for 2 hours to obtain a lump in which the inorganic powder was coated with an epoxy resin. (3) Then, using a ball mill, rotate the mass 20 times.
Coarse crushing at 00 rpm, and further alumina balls (10 mmφ)
Was pulverized to obtain heat-resistant fine powder having an average particle size of 3 to 5 μmφ. (4) Next, a printed wiring board was manufactured in the same manner as in Example 1 using the heat-resistant fine powder obtained in (1) to (3) above.

A printed wiring board manufactured by using the heat-resistant fine powder obtained by variously changing the volume ratio of the inorganic powder to the fine powder obtained by coating the inorganic powder with the heat-resistant resin in the above-mentioned Example 4 was manufactured by using an organic resin. Based on a comparison with a printed wiring board manufactured using a heat-resistant fine powder consisting of a single substance or a single inorganic powder, the adhesion strength (peeling strength, JIS-C-6481) between the substrate and the copper plating film, the adhesive layer The coefficient of thermal expansion and the state after the thermal cycle test were evaluated. The results are shown in Table 3.

[0047]

[Table 3]

(Example 5) (1) Bisphenol A type epoxy resin (made by Yuka Shell)
100 parts by weight of nonionic surfactant (made by NOF Corporation) 6
40 parts by weight of whiskers (manufactured by Tokai Carbon, 1 μmφ, 30 μm) were added, and the mixture was stirred and mixed. (2) Next, while stirring this epoxy resin solution at 1000 rpm with a homodisper, 3 parts by weight of 30 parts by weight of water were added by a buret to prepare an epoxy emulsion. (3) Next, 9 parts by weight of a triethylenetetramine curing agent was added to this epoxy emulsion, and the mixture was left to stir at room temperature for 50 minutes to prepare a heat resistant fine powder. (4) Next, a printed wiring board was manufactured in the same manner as in Example 1 using the heat-resistant fine powder obtained in (1) to (3) above.

The printed wiring board manufactured by using the heat-resistant fine powder obtained by variously changing the volume ratio of the inorganic powder to the fine powder obtained by coating the inorganic powder with the heat-resistant resin in the above-mentioned Example 5 was manufactured by using the organic resin. Based on a comparison with a printed wiring board manufactured using a heat-resistant fine powder consisting of a single substance or a single inorganic powder, the adhesion strength (peeling strength, JIS-C-6481) between the substrate and the copper plating film, the adhesive layer The coefficient of thermal expansion and the state after the thermal cycle test were evaluated. The results are shown in Table 4.

[0050]

[Table 4]

As is clear from the results shown in Tables 1 to 4, the peel strength of the printed wiring board according to the present invention is higher than that of the comparative example using the heat resistant fine powder made of the organic resin alone or the inorganic powder alone. It was confirmed to be excellent. It was found that the reason for this is that the heat-resistant fine powder of the present invention makes it difficult for the resin component of the fine powder to remain in the anchor when the anchor is formed on the surface of the adhesive layer. In particular, it has been confirmed that it is preferable that the volume ratio of the inorganic powder to the fine powder obtained by coating the inorganic powder with the heat resistant resin is 20 to 40%. Furthermore, according to the observation after the thermal cycle test of the printed wiring board, the printed wiring board of the present invention has a low coefficient of thermal expansion of the adhesive layer, so that the thermal expansion coefficient difference between the adhesive layer and the plating film is 1000 cycles. The adhesive layer did not crack and the plating film did not peel off.

Then, in carrying out the above-described embodiment, the present inventors investigated the state of deterioration of the roughening liquid for anchor formation. As a result, it was also found that when the heat-resistant fine powder according to the present invention is used, the amount of resin eluted into the roughening liquid is reduced, and the life of the roughening liquid can be significantly improved.

(Example 6) (1) A thermoplastic resin (polyethylene) was hot-pressed,
It was formed into a handle shape. (2) Next, this shape was immersed in the adhesive solution prepared in Example 1, dried and cured to form an adhesive layer on the surface thereof. (3) Next, roughening was performed under the same conditions as in Example 1, and electroless copper plating was performed. (4) Then, the surface of the copper plating was subjected to electrolytic plating according to a conventional method to obtain a handle having a nickel luster. This confirmed that the adhesive of the present invention can be applied to fields other than wiring boards.

[0054]

As described above, the adhesive according to the present invention has a coefficient of thermal expansion similar to that of plated metal, and has chemical resistance and heat resistance even in an environment such as a thermal cycle test. , Adhesion with electroless plating film is extremely good without impairing the electrical characteristics and hardness. Moreover, with regard to such an adhesive, the amount of resin to be dissolved and removed is significantly reduced, as compared with the conventional printed wiring board using the anchor in which the heat-resistant fine powder made of a resin simple substance is dissolved and removed.
The anchor is easily formed, and as a result, the amount of resin eluted into the roughening liquid is reduced, deterioration of the roughening liquid can be suppressed, and the life of the roughening liquid can be significantly improved. Therefore, it is possible to provide an inexpensive printed wiring board in which cracks are not generated in the adhesive layer and the plating film is not peeled off.

[Brief description of drawings]

FIG. 1 is a cross-sectional view showing the shape of a heat-resistant fine powder according to the present invention.

Claims (3)

[Claims] 1. An adhesive obtained by dispersing a heat-resistant fine powder in an uncured heat-resistant resin matrix that exhibits a property of being hardly soluble in an acid or an oxidizing agent when subjected to a curing treatment. An adhesive characterized by using, as the above-mentioned heat-resistant fine powder, an inorganic powder coated with a heat-resistant resin that has been cured and is soluble in an acid or an oxidizing agent. 2. The adhesive according to claim 1, which is provided in a sheet shape or a prepreg shape. 3. A heat-resistant fine powder is dispersed on at least one surface of a substrate in an uncured heat-resistant resin matrix exhibiting a property of being hardly soluble in an acid or an oxidizing agent when it is cured. In a printed wiring board having an adhesive layer provided thereon, an adhesive layer provided thereon, and a conductor circuit provided thereon, a curing treatment in which an inorganic powder is soluble in an acid or an oxidant as the heat-resistant fine powder. A printed wiring board characterized by using a material coated with a heat-resistant resin as described above.