JPH07188935A - Adhesive having excellent anchor characteristic and printed circuit board formed by using this adhesive and its production - Google Patents

Abstract

PURPOSE:To obtain an adhesive having excellent anchor characteristics by treating the adhesive formed by dispersing a specific ratio of resin fillers into a resin matrix with a chrome sulfuric acid, thereby forming anchors of a specific opening diameter and depth. CONSTITUTION:The adhesive formed by dispersing 15 to 25 pts.wt. resin fillers having an average grain size of 3 to 10mum into the resin matrix is formed to a sheet form of 10 to 7Omum thickness. This adhesive is subjected to a chrome sulfuric acid treatment, by which its surface is roughened. The chrome sulfuric acid is preferably formed by mixing 300 to 5O0g/l chromic acid and 200 to 400g/l sulfuric acid at a volumetric ratio of 1:(0.6 to 1). The ratio of solubility of the resin filler and the resin matrix to such chrome sulfuric acid is preferably filler: matrix = (200 to 5000):1 by volume. As a result, the primary anchors having an opening diameter 1 of 10 to 20mum formed by dissolution of the matrix and the filler and the secondary anchors having an opening diameter 3 of 3 to 10mum formed by dissolution of the filler are formed at a total depth 4 of 12 to 20mum.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an adhesive having excellent anchor properties, a printed wiring board using this adhesive, and a method for producing the same.

[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.

Therefore, recently, as a method for forming a conductor on a printed wiring board, an adhesive is applied to the surface of the substrate to form an adhesive layer, the surface of the adhesive layer is roughened, and then roughened. The additive method of forming a conductor by applying electroless plating or the like on the adhesive layer has been receiving attention.

In this additive method, the resin insulating layer and the conductor layer are sequentially formed on the substrate by using an adhesive. Therefore, in order to improve the reliability of the wiring board, the resin insulating layer and the conductor layer are combined with each other. Adhesion is important.

On the other hand, conventionally, an adhesive agent in which a resin filler is dispersed in a resin matrix has been proposed in order to improve the adhesion between the resin insulating layer and the conductor layer. According to such an adhesive, the surface of the adhesive layer made of the adhesive is roughened due to the difference in solubility between the filler and the matrix with respect to the oxidizing agent and the like, so that an anchor depression effective for improving the adhesiveness is formed. Can be formed.

The technique relating to the formation of such an anchor was previously proposed by the inventors as a part of the technique for manufacturing a wiring board in Japanese Patent Laid-Open No. 61-276875. That is, in this prior proposal technique, a pre-cured heat-resistant resin powder that is soluble in an oxidant is dispersed in an uncured heat-resistant resin liquid that is hardly soluble in an oxidant by the curing treatment. And an adhesive characterized in that it is applied to a substrate, and then dried and cured to form an adhesive layer, and at least a part of the fine powder dispersed in the surface layer portion of the adhesive layer. Is dissolved and removed to roughen the surface of the adhesive layer, and then electroless plating is performed, which is a method for manufacturing a wiring board.

According to this technique, the above-mentioned adhesive is a heat-resistant resin fine powder which has been preliminarily cured, dispersed in a heat-resistant resin liquid, and when this adhesive is applied to a substrate and dried and cured, it forms a matrix. 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, the adhesive layer is treated with an oxidizing agent or the like to be dispersed on the surface portion of the adhesive layer. The fine powder present is mainly dissolved and removed. As a result, uniform anchor depressions are formed on the surface of the adhesive layer, and the adhesion between the adhesive layer and the electroless plated film can be improved.

[0008]

Now, the inventors of the present invention will further develop the above-mentioned conventional technique with the aim of developing a technique capable of stably obtaining high adhesion between the adhesive layer and the electroless plating film. I continued my research. As a result, as shown in FIG. 1, the shape of the anchor depression formed in the adhesive layer is such that the opening diameter of the primary anchor formed due to the dissolution of the resin matrix and the resin filler has an appropriate width. However, it is ideal that the secondary anchor formed due to the dissolution of the resin filler is reasonably large, and the total depth of the primary and secondary anchors from the adhesive layer surface is about 20 μm. Was newly discovered.

Further, according to experiments conducted by the inventors, chromic acid, which has been conventionally adopted and used as an acid or an oxidizing agent for forming an anchor, has an extremely wide control range for obtaining an anchor having an ideal shape as described above. It was a narrow one. That is, in the case of chromic acid, the shape of the anchor obtained by the action of chromic acid is generally such that the opening diameter formed due to the dissolution of the resin matrix is narrow, and the etching amount of chromic acid increases as the etching amount increases. We have noticed that there is a problem that the etching depth decreases with time because the change with time becomes severe.

To solve such a problem, a method of controlling the treatment time with chromic acid by improving the solubility of the resin matrix in an acid or an oxidizing agent can be considered. In this method, the heat resistance of the resin matrix is improved. In order to reduce the chemical resistance and the chemical resistance, a new problem has arisen that the reliability of the adhesive layer, and eventually the reliability of the wiring board, is also deteriorated.

[0011] Therefore, an object of the present invention is to solve the above-mentioned problems of the prior art, and in particular,
An adhesive having excellent so-called anchor characteristics, which exhibits characteristics such that an adhesive layer having an ideally-shaped anchor on the surface can be stably obtained without lowering the heat resistance and chemical resistance of the resin matrix, The purpose is to establish a technology for a printed wiring board using this adhesive.

[0012]

[Means for Solving the Problems] In order to achieve the above-mentioned object, the inventors have focused their attention mainly on the difference in solubility between a resin filler and a resin matrix with respect to an oxidizing agent and the like, and as a result of continuing diligent research, the average particle diameter: 3 μm It was found that it is effective to use a predetermined amount of resin filler of less than 10 μm and to use chrome sulfuric acid as a roughening liquid as a main agent,
The present invention was conceived.

That is, the adhesive of the present invention is an adhesive obtained by dispersing 15 to 25 parts by weight of a resin filler having an average particle size of 3 μm or more and less than 10 μm in a resin matrix. The opening diameter of the primary anchor formed due to the dissolution of the resin matrix and the resin filler due to the oxidizing agent treatment is within the range of 10 μm to 20 μm, and due to the dissolution of the resin filler due to the oxidizing agent treatment. The secondary anchor to be formed has an opening diameter in the range of 3 μm or more and less than 10 μm, and the total depth of the primary and secondary anchors from the surface of the adhesive is in the range of 12 to 20 μm. It is an adhesive with excellent anchor characteristics, characterized by an oxidizing agent treatment of 300 to form the anchor.
It is preferable that the roughening treatment is performed with chromic sulfuric acid in which chromic acid of 500 g / l and sulfuric acid of 200 to 400 g / l are mixed at a volume ratio of 1: (0.6 to 1). Further, the solubility ratio of the resin filler and the resin matrix to chromic sulfuric acid is preferably a volume ratio of filler: matrix = (200 to 5000): 1. Further, the adhesive has a thickness of 10-70.
It is desirable that the sheet has a thickness of μm, more preferably 10 to 40 μm. Then, the method for producing a printed wiring board of the present invention using the above adhesive forms an adhesive layer on a substrate,
A method for manufacturing a printed wiring board by roughening the surface of this adhesive layer and then performing electroless plating to form a conductor circuit, which does not exhibit a property of being poorly soluble in chromium sulfate after curing treatment. An adhesive is prepared by dispersing 15 to 25 parts by weight of a resin filler having an average particle diameter of 3 μm or more and less than 10 μm in a cured resin matrix, and then applying the adhesive to at least one of the substrate surfaces or Stick and dry, and then the surface of the obtained adhesive layer
Chromic acid of 0 to 500 g / l and sulfuric acid of 200 to 400 g / l were mixed at a volume ratio of 1: (0.6 to 1) to roughen the mixture to form a resin matrix on the surface of the adhesive layer. The opening diameter of the primary anchor due to the dissolution of the resin filler is 10μ
m to 20 μm or less, the opening diameter of the secondary anchor due to the dissolution of the resin filler is 3 μm to less than 10 μm, and the total depth from the layer surface of the entire anchor is 12 to 20 μm.
Is formed, and then the surface of this adhesive layer is subjected to electroless plating. Furthermore, the printed wiring board of the present invention obtained by the manufacturing method described above,
A printed wiring board is provided with a layer of the adhesive and a conductor layer of electroless plating and / or electroplating on a substrate.

[0014]

The characteristics of the adhesive according to the present invention are as follows. The opening diameter of the primary anchor thus formed is 10 μm or more and 20 μm or less, which is larger than that when chromic acid is used. As a result, the throwing power of the plating is improved, and the filling rate of the conductor inside the anchor can be improved.

For example, when a mixture of an epoxy resin fine powder as a resin filler and a phenol novolac type epoxy resin and a bisphenol A type epoxy resin as a resin matrix is used, the solubility ratio of the resin filler to the resin matrix in chromic acid is By ratio,
Filler: matrix = about 10 ⁴ : 1 and the matrix is apt to remain, and the opening of the primary anchor is thin and the anchor is likely to be deep throughout. In this respect, the solubility ratio of the resin filler and the resin matrix to chromic sulfuric acid is a volume ratio of filler: matrix = 1000: 1, and it is possible to increase the solubility of the resin matrix without changing the solubility of the resin filler. Therefore, it is possible to obtain an anchor having an ideal opening diameter of the primary anchor.

The second characteristic of the adhesive according to the present invention is that 15 to 25 parts by weight of a resin filler having an average particle diameter of 3 to 10 μm is dispersed in the resin matrix. This allows
The secondary anchor can have a suitable size, and the biting of the resin portion with respect to the conductor portion can be enhanced. That is, it is possible to obtain an ideal anchor shape for obtaining high peel strength (adhesion strength between the adhesive layer and the plating film).

Here, in the present invention, the reason why the average particle size of the resin filler is limited to the above range is that in order to increase the bite of the resin portion with respect to the conductor portion by making the secondary anchor a suitable size, It is necessary that the average particle diameter of 3 is 3 μm or more, while if the average particle diameter of the resin filler exceeds 10 μm, it is not possible to obtain a fine uneven surface and a uniform anchor density. Further, the reason for limiting the content of the resin filler having the above average particle diameter to the above range is that if it is less than 15 parts by weight, the anchor is not clearly formed, and the biting of the resin portion with respect to the conductor portion is insufficient,
On the other hand, if it exceeds 25 parts by weight, the surface of the adhesive layer becomes porous,
This is because the adhesive strength between the adhesive layer and the plating film is reduced. When a resin filler having an average particle diameter of 0.8 μm or less is mixed with the above resin filler to form mixed particles, it can be dispersed and mixed in the resin matrix in the range of 3 to 15 parts by weight.

Such an adhesive of the present invention relates to the shape of the anchor formed by the treatment of the adhesive layer with chromium sulfate, and the opening diameter of the primary anchor formed by the dissolution of the resin matrix is 10 To 20 μm, the opening diameter of the secondary anchor formed due to the dissolution of the resin filler is in the range of 3 μm to less than 10 μm, and the total depth of the primary and secondary anchors from the adhesive surface. 12 to 20 μm
Shall have the following characteristics. The reason for this is that if the content deviates from these ranges, the filling rate of the plating decreases and the biting of the conductor portion with respect to the resin portion becomes insufficient.

In the present invention, the treatment with chromic sulfuric acid for forming the anchor is performed by adding 300 to 500 g / l chromic acid and 20% chromic acid.
A roughening treatment with chromium-sulfuric acid mixed with 0 to 400 g / l of sulfuric acid at a volume ratio of 1: (0.6 to 1) is preferable.
The reason for this is that if the chromic acid concentration ratio is less than 300 g / l, the required anchor depth cannot be obtained, and if it exceeds 500 g / l, the etching speed deteriorates rapidly and the anchor depth increases due to deterioration. This is because the

According to the adhesive of the present invention as described above, it is possible to stably form an adhesive layer having an ideal anchor on the surface without deteriorating the heat resistance and chemical resistance of the resin matrix. Obtainable.

By the way, in the adhesive as in the present invention, an epoxy resin can be used as the thermosetting resin component of the resin matrix insoluble in acid or oxidizing agent, while it can be used as a resin filler soluble in acid or oxidizing agent. Also, an epoxy resin can be used. This point will be described below by taking solubility in an oxidizing agent as an example. The physical properties of the epoxy resin can be greatly varied by controlling these prepolymers (polymers having a relatively low molecular weight of about 300 to 10,000), the type of curing agent, and the crosslinking density. This difference in physical properties is not an exception even with respect to the solubility in an oxidizing agent, and can be adjusted to an arbitrary one by appropriately selecting the type of prepolymer, the type of curing agent, and the crosslinking density. For example, as the "oxidizing agent-soluble epoxy resin" constituting the resin filler, (A) "Alicyclic epoxy is selected as the epoxy prepolymer, a chain aliphatic polyamine curing agent is used as the curing agent, and cross-linking is performed. The molecular weight between points (the molecular weight between cross-linking points; the larger the cross-linking density, the lower the cross-linking density) is about 700. On the other hand, as the "hardly soluble (including insoluble) epoxy resin in the oxidizing agent" which is the thermosetting resin component of the resin matrix, (B) "bisphenol A type epoxy resin is selected as the epoxy prepolymer, An aromatic diamine-based curing agent was used as the curing agent, and the molecular weight between the crosslinking points was cross-linked to about 500 ", or the solubility was lower than this (C).
"Phenolic novolac type epoxy resin was selected as the epoxy prepolymer, an acid anhydride type curing agent was used as the curing agent, and the molecular weight between crosslinking points was crosslinked to about 400."
Is used. Further, the epoxy resin (B) can also be used as the "oxidizing agent-soluble epoxy resin". In this case, the epoxy resin (C) is adopted as the "oxidizing agent-insoluble epoxy resin". . As described above, the epoxy resin is a kind of prepolymer,
By appropriately selecting the type of curing agent and the crosslinking density,
It can be adjusted to have any solubility. Further, as understood from the above-mentioned examples, being soluble in an oxidizing agent or sparingly soluble (or insoluble) in an oxidizing agent means a relative dissolution rate with respect to the oxidizing agent. As the epoxy resin filler, the one having a difference in solubility may be arbitrarily selected. In addition, as means for making the difference in solubility between the resins, the kind of prepolymer,
The method is not limited to the adjustment of the type of the curing agent and the crosslinking density, and other means may be used. Table 1 shows the prepolymer, curing agent, and
The cross-linking density and solubility are listed.

[0022]

[Table 1]

In the present invention, the solubility difference of each epoxy resin as described above is utilized to obtain the solubility ratio of the resin filler and the resin matrix with respect to the chromic sulfuric acid as a volume ratio of filler: matrix = (200 to 5000). 1 (see FIG. 2), and the oxidation treatment is performed for a certain period of time. By performing such a treatment, the soluble epoxy resin fine powder having the highest solubility in the oxidizing agent is vigorously dissolved, and a large recess is formed. At the same time, the epoxy resin matrix, which is hardly soluble in the oxidizing agent, remains to form an anchor (roughened surface) as shown in FIG.

Next, a method of manufacturing the printed wiring board according to the present invention will be described. The method for producing a printed wiring board of the present invention is as follows. First, a resin filler having an average particle diameter of 3 to 10 μm is added to an uncured resin matrix that exhibits a property of being hardly soluble in chromium sulfate when it is cured. The 15
It begins with the step of preparing an adhesive having about 25 parts by weight dispersed therein.

As the resin filler used in the method of the present invention, the above-mentioned resins are preferable, but they are excellent in heat resistance, electric insulation, chemical stability and adhesiveness, and are resistant to chromic sulfuric acid. Any soluble and cured resin can be used. For example, amino resin (melamine resin, urea resin, guanamine resin), polyester resin,
A bismaleimide triazine resin or the like can be used.

The particle size of this resin filler is such that in terms of obtaining a fine uneven surface and a uniform anchor density, the average particle size is
It may be less than 10 μm, but for the purpose of increasing the size of the secondary anchor and increasing the bite of the resin part with respect to the conductor part, the average particle size of 3 μm or more and less than 10 μm is 15 to 25 in the outer frame amount. It is necessary to include a part by weight, and further, those having an average particle size of 0.8 μm or less may be included in the range of 3 to 15 parts by weight in terms of the outer frame amount.

As the resin matrix in which the resin filler is dispersed, the above-mentioned resins are suitable, but they are excellent in heat resistance, electric insulation, chemical stability and adhesiveness, and are hardened by treatment to produce chromium sulfate. Any resin can be used as long as it has a property of being hardly soluble in, and it may be a photosensitive resin. Further, in this resin matrix, for example, an organic filler such as a fluororesin, a polyimide resin or a benzoguanamine resin, or a filler made of an inorganic fine powder such as silica, alumina, titanium oxide or zirconia may be appropriately blended. Also, additives such as colorants (pigments), leveling agents, defoaming agents, ultraviolet absorbers, flame retardants and the like may be compounded and added.

As the curing agent for the resin matrix,
DICY, amine curing agents, acid anhydrides and imidazole curing agents can be used. In particular, when the resin matrix is an epoxy resin, it is preferable to use an imidazole-based curing agent. When this imidazole-based curing agent is used, especially when it is applied to an adhesive obtained by dispersing a resin filler in a thermosetting resin matrix which is either an uncured polyfunctional epoxy resin or a bifunctional epoxy resin, It is desirable to extend the pot life (usable time) by separately storing the imidazole-based curing agent and the adhesive, and mixing and using the both immediately before use.

Although a resin containing no solvent can be used as it is for the resin matrix, it is preferably used in the state of a resin solution prepared by dissolving the 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 dispersed uniformly, and is easier to apply to the substrate and more easily to form a sheet. As a solvent used for dissolving this resin, 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 usually suitable. .

In the next step, the prepared adhesive is applied to at least one surface of the substrate and dried when the adhesive is a coating liquid, and when it is a sheet, it is applied. This is a process of forming an adhesive layer on the substrate by attaching this. Here, the layer of this adhesive is the same as the above-mentioned method of applying using a roll coater or the like, pasting the sheet-shaped or prepreg-shaped adhesive on the substrate, and other similar effects. May be formed by a method that produces When a sheet-shaped adhesive is used, its thickness is 10 to 70 μm, preferably 10 to 70 μm.
40 μm. The reason is that the thickness of the sheet adhesive is 10
This is because if it is less than μm, it is too thin and the workability is poor and the anchor depth is insufficient, while if it exceeds 70 μm, the cost becomes high.

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.
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.

In the next step, the surface of the obtained adhesive layer was mixed with chromic acid of 300 to 500 g / l and sulfuric acid of 200 to 400 g / l at a volume ratio of 1: (0.6 to 1). Roughened with sulfuric acid, the opening diameter of the primary anchor formed on the surface of the adhesive layer due to the dissolution of the resin matrix is in the range of 10 to 20 μm, and it is formed due to the dissolution of the resin filler. This is a process for forming an anchor in which the opening diameter of the secondary anchor is in the range of 3 to 10 μm, and the total depth of the primary and secondary anchors from the surface of the adhesive layer is in the range of 12 to 20 μm.

The roughening with chromium sulphate is carried out by immersing the substrate on which the adhesive layer is formed in the chromic sulfuric acid solution or by spraying the solution onto the substrate. By this treatment, the surface of the obtained adhesive layer becomes a roughened surface having excellent anchor properties. 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.

In the manufacturing method of the present invention, after the roughening step, the substrate having the roughened adhesive layer surface is dipped in a permanganate solution so that the adhesive layer surface and the through holes are Performing so-called desmear treatment, which is a smear removal treatment, is effective for obtaining a roughened surface having excellent anchor characteristics.

The next step is a treatment for forming a predetermined conductor pattern by subjecting the surface-roughened adhesive layer on the substrate to electroless plating and / or electroplating. Here, the conductor pattern can be formed by electroless plating and / or electroplating by various methods that have been carried out for known printed wiring boards.
For example, a method of etching a circuit after applying electroless plating to the substrate, a method of directly forming a circuit when applying electroless plating, or the like can be applied. As the above electroless plating or electroplating, for example, copper plating, nickel plating, tin plating, gold plating and silver plating can be applied, and particularly at least one method of copper plating, nickel plating and gold plating is used. Is preferred.

In the production method of the present invention as described above, the chromium sulfate used as the roughening liquid is, as shown in FIG. 3, the trivalent chromium ion as compared with chromic acid, as shown in FIG. The increase in the concentration is moderate, and the etching power hardly changes with time. As a result, the control range of chromic sulfuric acid can be set wide, and moreover, the total depth of the primary and secondary anchors from the surface of the adhesive layer can be preferably maintained within a wide concentration range.

In the printed wiring board of the present invention obtained by the above-described manufacturing method, the adhesive layer according to the present invention described above and the electroless-plated and / or electroplated conductor layer are: It is provided on the substrate. For example, a single-sided printed wiring board formed with a plating resist and a conductor circuit via an adhesive layer formed on a substrate, a double-sided board formed with a conductor circuit through an adhesive layer and through holes formed on both sides of the substrate. There is a through-hole printed wiring board, 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, and the like. .

[0038]

【Example】

(Example 1) (1) Phenol novolac type epoxy resin 50 parts by weight, bisphenol type epoxy resin 50 parts by weight, and particle size 0.5
An adhesive containing epoxy resin fine powder as a main component was prepared from 5 parts by weight of μm and 20 parts by weight of 5.5 μm in particle size. (2) The above-mentioned adhesive was formed into a sheet in advance, and this adhesive sheet was pressure-bonded to the glass epoxy resin substrate simultaneously on the front and back sides. (3) After the protective film on the pressure-sensitive adhesive sheet was peeled off, heat treatment was carried out at 120 ° C. for 3 hours and 150 ° C. for 1 hour, and the adhesive sheet was dried. (4) After performing the treatment of (3) above,
An oxidizer in which the ratio of Cr ³⁺ composed of a mixed liquid of CrO ₃ and H ₂ SO ₄ in the total Cr is 0.50% (volume ratio of chromic acid and sulfuric acid is 1:
The surface of the adhesive sheet was roughened by immersing it in 70% chrome sulfuric acid) mixed at 0.6 for 30 minutes. (5) Next, the surface roughened surface is washed with water, and 400 g of sodium sulfite is added.
It was immersed in an aqueous solution of / l for 20 minutes at room temperature to neutralize Cr ⁶⁺ . Then, it was thoroughly washed with water and dried at 100 ° C. for 2 hours to obtain an adhesive layer having an anchor. (6) Electroless plating was performed on the obtained adhesive layer by an additive method to manufacture a printed wiring board having a predetermined conductor pattern.

Table 2 also shows the results of measuring the peel strength of the conductor layer of the printed wiring board manufactured as described above. Table 2 shows the results of measuring the shape of the anchor formed on the surface of the adhesive layer. As is clear from the results shown in Table 2, in the case of the concentration of chromic sulfuric acid or the anchor shape adapted to the present invention, the peel strength is superior to the case where only chromic acid is used as the oxidizing agent. It was confirmed.

In the above example, the anchor shape was measured by the following method. That is, after plating, the test piece is fractured, and the anchor portion of the adhesive layer present on the fracture surface is observed by SEM at 5 or more locations (× 50
0, × 1000, × 2000). Then, using the obtained SEM photograph, was measured with a scale as shown in FIG. 1 (b) (the number of measurements = 20 or more).

[0041]

[Table 2] : Opening diameter of primary anchor (μm) due to dissolution of resin matrix and resin filler: Opening diameter of secondary anchor (μm) due to dissolution of resin filler: Of primary / secondary anchor from adhesive surface Total depth (μm)

[0042]

As described above, according to the adhesive of the present invention, it is possible to form an adhesive layer having an ideal anchor on the surface without lowering the heat resistance and chemical resistance of the resin matrix. It can be stably obtained. This makes it possible to stably provide a printed wiring board having excellent reliability such as peel strength. Moreover, in the present invention, since chromium sulfuric acid is used as the roughening liquid, the etching power hardly changes with time, the control range can be set broadly, and the productivity is excellent.

[Brief description of drawings]

FIG. 1 is (a) a cross-sectional photograph and (b) an ideal shape of an anchor depression formed in an adhesive layer.

FIG. 2 is a diagram showing the relationship between the solubility ratio of a resin filler in a matrix resin and the peel strength.

FIG. 3 is a diagram showing a relationship between etching power and Cr ³⁺ absorbance.

Claims (6)

[Claims] 1. An average particle diameter of 3 μm in a resin matrix.
An adhesive obtained by dispersing 15 to 25 parts by weight of a resin filler of m or more and less than 10 μm, the adhesive being a primary material formed by dissolution of a resin matrix and a resin filler accompanying chrome-sulfuric acid treatment. Anchor opening diameter is 10 μm or more 20
the diameter of the secondary anchor is 3 μm or more and less than 10 μm, and the diameter of the secondary anchor formed due to the dissolution of the resin filler accompanying the treatment with chromium sulfate is within the range of 3 μm or more and less than 10 μm. Total depth of secondary and secondary anchors is 12
An adhesive having excellent anchor properties, which is characterized by having a property within a range of up to 20 μm. 2. The chromium sulfate treatment for forming the anchor is performed by mixing chromium sulfate of 300 to 500 g / l and sulfuric acid of 200 to 400 g / l at a volume ratio of 1: (0.6 to 1). The adhesive according to claim 1, which is a roughening treatment. 3. The adhesive according to claim 1, wherein the ratio of the solubility of the resin filler and the resin matrix in chromic sulfuric acid is the volume ratio of filler: matrix = (200 to 5000): 1. 4. The adhesive according to claim 1, which is in the form of a sheet having a thickness of 10 to 70 μm. 5. A method for producing a printed wiring board by forming an adhesive layer on a substrate, roughening the surface of the adhesive layer, and then performing electroless plating to form a conductor circuit, which comprises a curing treatment. After that, an uncured resin matrix showing a property of being poorly soluble in chromium sulfate is prepared by dispersing 15 to 25 parts by weight of a resin filler having an average particle diameter of 3 μm or more and less than 10 μm, to prepare an adhesive. Then, this adhesive is applied or adhered to at least one of the substrate surfaces and dried, and then the surface portion of the obtained adhesive layer is treated with 300 to 500 g / l chromic acid and 200 to 400 g / l. Sulfuric acid and volume ratio 1: (0.6-
By roughening with the chromic sulfuric acid mixed in 1), the opening diameter of the primary anchor resulting from the dissolution of the resin matrix and the resin filler on the surface of the adhesive layer is 10 μm or more and 20 μm or more.
An anchor having a secondary anchor opening diameter of 3 μm or more and less than 10 μm and a total depth from the layer surface of the entire anchor of 12 to 20 μm is formed, and then the adhesive A method for manufacturing a printed wiring board, which comprises subjecting a layer surface to electroless plating. 6. A printed wiring board having a layer of the adhesive according to claim 1 and a conductor layer of electroless plating and / or electroplating provided on a substrate.