JP2000059036A - Manufacture of multilayer printed wiring board - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method of manufacturing a multilayer printed wiring board, which manufactures the wiring board into a multilayer printed wiring board, having high adhesion and high intercircuit insulation properties and also can obtain the wiring board by a build-up technique. SOLUTION: In a method of manufacturing a multilayer printed wiring board of a structure, wherein a polyimide resin solution containing a solvent soluble polyimide resin and fine grains, which are more satisfactory than the polyimide resin in a solubility to an oxidizing agent, is applied on one part of an insulating board formed with a conductor circuit to form a polyimide resin layer through electrodeposition, an insulating layer is formed by removing a solvent from the polyimide resin layer and a metal film is formed on the surface of the insulating layer by plating, the insulating layer is formed of a first polyimide resin film containing lower than 0.1 volume % of fine grains and a second polyimide rein film containing 0.1 to 50 volume % of fine grains on the surface of the first polyimide resin film, the thickness of the first polyimide resin film is 3 μm or larger, the fine grains being contained in the second polyimide resin film are resin fine grains, and the mean grain diameter of the resin fine grains is set in the range of 0.01 to to 10 μm.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an improvement in a method for manufacturing a multilayer printed wiring board which can be made high in density and has excellent adhesion reliability and inter-circuit insulation reliability.

[0002]

2. Description of the Related Art A multilayer printed wiring board is formed by laminating a plurality of conductor layers and insulating layers. In recent years, as portable electronic devices have become smaller and thinner, the multilayer printed wiring board as a component thereof has been developed. The size and thickness of the plate have also been required to be high, that is, high density. One way to meet this demand is to increase the conduction density between the conductor layers of the multilayer printed wiring board by using a non-penetrating type in which holes conducting between the conductor layers can be obtained from the conventional through-type through-holes between any conductor layers. The diameter of the hole is reduced by using the via hole.

A build-up method has attracted attention as a method of manufacturing a multilayer printed wiring board that satisfies this method. As one of the methods, an insulating resin layer is formed on the surface of a printed wiring board serving as a core material. After drilling through-holes or via-holes that provide conduction between conductor layers according to the requirements, the surface of the insulating resin layer, including the side walls of the holes, is roughened by etching, and then electroless plating, etc. After forming a copper film or the like and conducting the treatment, a process of increasing the thickness of the copper film by electroplating to a desired thickness, if necessary, and then patterning and forming a circuit is repeated a desired number of times. There is a method of manufacturing a multilayer printed wiring board. In the multilayer printed wiring board obtained by this method, a via hole having a diameter of about 100 μm can be used as a conductive hole between conductive layers, and only a through hole having a diameter of several hundred μm machined by a conventional drill or the like is used. Compared with a multilayer printed wiring board having a hole for conduction between conductive layers, there is a possibility that conduction density between conductive layers can be greatly increased.

However, one of the biggest problems in the above method is that the adhesion strength of the plating film applied to the surface of the insulating resin layer cannot be sufficiently obtained. In order to solve this problem, fine particles having different solubility from the insulating resin are contained in the insulating resin layer, and the fine particles are selectively eluted during the etching treatment of the surface of the insulating resin layer, and the surface of the insulating resin layer is selectively dissolved. A method of forming a so-called anchor effect between a fine and complicated uneven portion and a plating film subsequently formed on the surface of the resin layer is used. In addition, although inorganic substances such as calcium carbonate have been conventionally used as the fine particles used at this time, a method using an organic substance in consideration of moisture resistance and insulation reliability has been studied.

[0005] However, although the multilayer printed wiring board obtained by this method has been partially put into practical use, since the resin used as the insulating resin layer is generally an epoxy resin, high-temperature heat resistance for a long period of time is required. In some applications, heat may cause problems such as deterioration of the insulating resin layer, so that sufficient reliability has not been obtained. Therefore, a method using a polyimide resin as the insulating resin layer has been studied as a means for dealing with problems such as deterioration due to heat. The formation of the polyimide resin layer is usually carried out by applying a polyamic acid, which is a precursor of the polyimide resin, and imidizing it by a heat treatment at about 400 ° C. However, in order to obtain the above-mentioned effects, when resin particles having excellent solubility are contained in the polyimide precursor, the resin particles are melted, deteriorated, carbonized, etc. by the high-temperature heat treatment during imidization, and the expected effect is obtained. In addition to this, in some cases, the properties of the entire insulating resin layer may be adversely affected.

In order to solve this problem, a method of applying a solvent-soluble polyimide resin solution containing the above resin fine particles to a substrate and then forming an insulating resin layer by heat treatment for removing the solvent is used. Was considered.

[0007]

According to this method, the heat treatment required for forming the insulating resin layer requires a temperature sufficient to remove the solvent, and the conventional method is not suitable for imidizing polyamic acid by thermal condensation. 400 needed
The present invention does not require a high-temperature heat treatment at a temperature of not less than ° C., sufficiently satisfies the intended purpose, and improves the adhesion between an insulating resin layer and a metal film formed on the surface thereof and its reliability.

On the other hand, from the viewpoint of the reliability of the multilayer printed wiring board, importance is also placed on the electrical insulation between the circuits. Among them, the electrical insulation between the circuits separated by the polyimide resin layer, that is, the insulation resistance between the circuits is particularly important. On the other hand, since the polyimide resin layer, which is an inter-circuit insulating layer, is also reduced in thickness with the demand for higher density and thinner insulating substrates, particularly high reliability is required. In this case, the multilayer printed wiring board obtained by applying the polyimide resin layer as described above is not sufficiently satisfactory in terms of inter-circuit insulation reliability. Specifically, after an environmental test performed by holding the insulating substrate at 85 ° C. under an environment of 85% relative humidity for 1000 hours and applying a predetermined voltage between circuits separated by the polyimide resin layer during that time, , 10 ¹⁰
It was hard to say that it had an insulation resistance value of Ω or more.

SUMMARY OF THE INVENTION It is an object of the present invention to provide a method of manufacturing a multilayer printed wiring board which has both high adhesion and inter-circuit insulation, which have been difficult in the past, and which can be obtained by a build-up method. is there.

[0010]

Means for Solving the Problems The present inventor has found that the reliability of insulation between circuits separated by a polyimide resin layer depends on fine particles co-deposited in the polyimide resin layer, and has completed the present invention. I came to.

[0011] The present invention for solving the above-mentioned problems is to provide at least a part of an insulating substrate on which a conductor circuit is formed, with fine particles which are more soluble in a solvent-soluble polyimide resin and an oxidizing agent than the polyimide resin. A polyimide resin solution containing is applied to form a polyimide resin layer by electrodeposition, a solvent is removed from the polyimide resin layer to form an insulating layer, and a metal film is formed by plating on the surface of the insulating layer. In the method for manufacturing a printed wiring board, at least a part of the insulating substrate has a first polyimide resin film containing less than 0.1% by volume of the fine particles, and the fine particles are coated on the surface of the first polyimide resin film. A method for producing a multilayer printed wiring board, wherein the insulating layer is formed by a second polyimide resin film containing 1 to 50% by volume. The thickness of the polyimide resin film is 3 μm or more, the fine particles contained in the second polyimide resin film are resin fine particles, and the fine particles contained in the second polyimide resin film have an average particle diameter of 0 μm. .01-
It is characterized by a range of 10 μm.

[0012]

BEST MODE FOR CARRYING OUT THE INVENTION The present invention forms fine and complicated irregularities on the surface of a polyimide resin insulating layer in order to improve the adhesion strength and reliability of the polyimide resin insulating layer and the metal film formed on the surface. When the polyimide resin layer is electrodeposited as described above, the technique is started from a technique in which fine particles having different solubility from the polyimide resin are co-deposited in the polyimide resin layer. The property that the fine particles are more soluble in the oxidizing agent than the polyimide resin is necessary to obtain an anchor effect that produces the adhesion strength between the polyimide resin insulating layer and the metal film, but generally the polyimide resin is Because the chemical stability is inferior, for example, when impurities and the like remain on the surface of the polyimide resin insulating layer in a circuit forming process, for example, the fine particles and the polyimide resin remaining on the polyimide resin insulating layer in the above-described environmental test The possibility that the migration of the impurity occurs via an interface or the like increases.

Therefore, in the present invention, the polyimide resin insulating layer formed by coating is divided into two resin films, whereby the adhesion reliability with the metal film formed on the insulating layer and the circuit separated by the polyimide resin insulating layer are separated. The present invention is characterized in that it is possible to achieve both insulation reliability between them. That is, the first formed first on the metal foil surface
In order to ensure high inter-circuit insulation reliability, it is necessary that the polyimide resin film does not contain fine particles having chemically inferior stability as much as possible, and the content thereof should be less than 0.1% by volume. It is important. If the fine particles are contained more than this, it becomes difficult to obtain sufficient inter-circuit insulation reliability. The thickness is 3
μm or more is preferable, and if it is less than 3 μm, it becomes difficult to obtain sufficient inter-circuit insulation reliability.

On the other hand, the second polyimide resin film formed on the surface of the first polyimide resin film has an average particle diameter within a predetermined range in order to secure reliability regarding adhesion strength with a metal film formed on the surface. Fine particles must be contained. In the present invention, as a method of forming a polyimide resin film, using a conventional polyamic acid, instead of a method of heat condensation,
This is performed by using a polyimide resin solution previously dissolved in a solvent and removing the solvent by heat treatment. In this method, depending on the type of the solvent used, for example, even when N-methyl-2-pyrrolidone which is a high boiling point solvent is used, a heat treatment at about 200 ° C. is sufficient.

The fine particles contained in the second polyimide resin film in the present invention may have any structure as long as they can be easily dissolved in a certain kind of solution as compared with the polyimide resin as a base material, and the structure is not particularly limited. Since the polyimide resin has high resistance to an ordinary oxidizing agent, it is preferable that the fine particles have a structure in which the fine particles are easily dissolved in the oxidizing agent. Further, from the viewpoints of compatibility with the polyimide resin of the base material and insulation reliability, it is preferable to use a resin such as a rubber-modified epoxy resin or butadiene rubber as the fine particles. The average particle size of the fine particles is preferably in the range of 0.01 to 10 μm. If the average particle size of the fine particles is less than 0.01 μm, the size and shape of the uneven portion formed on the surface of the polyimide resin insulating layer after the etching treatment is insufficient to obtain a sufficient anchor effect, On the other hand, when the average particle size is 1
If it exceeds 0 μm, there is no problem in terms of the anchor effect,
Since the irregularities on the surface of the insulating resin layer become severe, problems such as residual etching during circuit patterning are likely to occur, and a sufficient thickness of the insulating layer may not be obtained. Note that it is preferable to avoid mixing of fine particles having an average particle diameter exceeding 3 μm into the first polyimide resin film as much as possible.

Further, it is important that the amount of the fine particles contained in the second polyimide resin film is in the range of 0.1 to 50% by volume, and the content of the fine particles is less than 0.1% by volume. In such a case, the density of the concavo-convex portions formed on the surface of the insulating resin layer after the etching treatment is insufficient to obtain a sufficient anchoring effect. This is because the characteristics of the resin layer cannot fully utilize the characteristics inherent to the polyimide resin.

Next, the method of forming a metal film on the surface of the polyimide resin insulating layer composed of two polyimide resin films, which is carried out in the present invention, is not particularly limited, and a sputtering method or a vapor deposition method can be employed. In order to densely fill the metal film in the fine irregularities formed on the surface and sufficiently obtain the anchor effect, an electroless plating method is particularly recommended. In addition, the electroless plating method is not particularly limited, and after forming a polyimide resin insulating layer, performing an appropriate etching treatment using a solution such as an oxidizing agent, and then adsorbing a catalytic metal such as palladium serving as a plating catalyst, followed by a known method. The electroless plating may be performed by the above method, and the thickness of the metal film can be increased by an electroplating method as necessary. Then, after patterning the circuit on the metal film formed on the surface of the insulating resin layer in the present invention, an insulating resin layer is further formed on the surface, and plating is repeated a desired number of times, whereby a multilayered printed wiring board is desired. In addition, by forming a conductive hole such as a through hole and a via hole in the insulating resin layer according to a known method, and forming a plating film including a side wall of the hole, the conductive layer can be electrically connected. It goes without saying that it can be obtained.

[0018]

Next, examples of the present invention will be described together with comparative examples. [Example 1] Length 335 mm, width 510 mm, thickness 0.4
A double-sided printed wiring board having a circuit with a minimum pitch of 100 μm was obtained by patterning a copper film with ferric chloride using a double-sided copper-clad glass epoxy resin substrate having a thickness of 18 μm (copper thickness: 18 μm). On the surface of the obtained core material, 70% by volume of a block copolymer type polyimide “Cubilon” (trade name, manufactured by PI Technology Research Institute),
And a polyimide resin solution comprising N-methyl-2-pyrrolidone as a solvent, dried at 90 ° C. for 30 minutes, and then heat-treated at 200 ° C. for 30 minutes to completely remove N-methyl-2-pyrrolidone in the polyimide resin film. Then, a first polyimide resin film having a thickness of 10 μm was formed.

Thereafter, 70% by volume of a block copolymer type polyimide "Cubilon" (trade name, manufactured by PI Technology Co., Ltd.) on the surface of the first polyimide resin film, and an average particle diameter of 10% by volume based on the polyimide resin. A 2 μm spherical rubber-modified epoxy resin, and a polyimide resin solution containing N-methyl-2-pyrrolidone as a solvent are applied, dried at 90 ° C. for 30 minutes, and then heat-treated at 200 ° C. for 30 minutes to form a polyimide resin film. A second polyimide resin film having a thickness of 10 μm was formed by completely removing N-methyl-2-pyrrolidone.

Then, using a carbon dioxide laser, a via hole having a processing energy of 210 J / cm ² , a number of shots of 3, and a diameter of 50 μm for conducting to the core material was formed at a desired position on the substrate. Further, through holes having a diameter of 400 μm were formed at desired locations on the substrate by drilling. Then 50 g / l potassium permanganate and 40 g / l
The substrate was immersed in a 70 ° C. aqueous solution containing g / liter of sodium hydroxide for 10 minutes to etch the surface of the polyimide resin insulating layer and remove the resin remaining between the circuit between the via hole and the core material.

Subsequently, the manganese remaining on the substrate was reduced and removed, and the substrate was further immersed in a catalyst application liquid “OPC-80 Catalyst M” (trade name, manufactured by Okuno Pharmaceutical Co., Ltd.) at 25 ° C. for 5 minutes. After washing with water, the catalyst activity promoting solution “OPC-
555 Accelerator ”(trade name, manufactured by Okuno Pharmaceutical Co., Ltd.) at 25 ° C. for 5 minutes and washed with water. Then, 10 g / l of copper sulfate pentahydrate, 30 g / l of disodium ethylenediaminetetraacetate, 5 ml / l of a 37% formaldehyde solution, 0.5 g / l of polyethylene glycol (molecular weight 1000),
It contains 10 mg / l of 2,2'-bipyridyl and contains p
The substrate was immersed for 20 minutes in an electroless copper plating solution at 65 ° C. in which H was adjusted to 12.5, so that the surface of the substrate including the via hole and the side wall of the through hole had a thickness of 0.5 mm.
A μm copper plating film was formed.

Thereafter, 80 g / l of copper sulfate pentahydrate, 180 g / l of sulfuric acid, and 60 mg of chloride ion
Immersion in an electrolytic copper plating solution at 23 ° C./liter containing a brightener at 10 ml / liter, using a phosphorus-containing copper plate as an anode, performing electrolytic copper plating at a cathode current density of 3 A / dm ² for 30 minutes, and forming a via hole and a through hole. An electrolytic copper plating film having a thickness of 18 μm was formed on the surface of the substrate including the side wall. Furthermore, using a photolithography technique on the surface of the electrolytic copper plating film according to the conventional method, the minimum pitch 1
After patterning the 00 μm etching resist,
After performing an etching treatment with a ferric chloride solution of 40 Baume at a temperature of 50 ° C. and a shower pressure of 2 kg / cm ² for 40 seconds, a circuit was formed by removing the resist layer. Through the above steps, a four-layer printed wiring board was obtained.

The adhesion strength of the plating film of the obtained four-layer printed wiring board is 1.5 kgf / cm, the insulation resistance between the circuits is 1 × 10 ¹³ Ω, and the insulation resistance between the circuits separated by the polyimide resin layer. The value was 1 × 10 ¹³ Ω. Further, the printed wiring board was allowed to stand still in a constant temperature and humidity chamber maintained at 85 ° C. under a relative humidity environment of 85%, and a voltage of 100 V was continuously applied between the respective circuits during that time. Then, the adhesion strength of the plating film after holding for 1000 hours in the above environment is 1.
0kgf / cm, insulation resistance between circuits is 1 × 10
The insulation resistance between the circuits separated by ¹² Ω and the polyimide resin layer was 1 × 10 ¹² Ω.

From the above results, it can be said that the multilayer printed wiring board obtained by the above method has sufficient adhesion reliability and inter-circuit insulation reliability.

Example 2 The procedure of Example 1 was repeated except that a rubber-modified epoxy resin having an average particle size of 0.01 μm was used and the content in the polyimide resin solution was set to 50% by volume based on the polyimide resin. A four-layer printed wiring board was obtained in the same procedure as in Example 1. The adhesion strength of the plating film of the obtained four-layer printed wiring board was 1.3 kgf / cm,
The insulation resistance between the circuits was 1 × 10 ¹³ Ω, and the insulation resistance between the circuits separated by the polyimide resin layer was 1 × 10 ¹³ Ω. Further, the printed wiring board was allowed to stand still in a constant temperature and humidity chamber maintained at 85 ° C. under a relative humidity environment of 85%, and a voltage of 100 V was continuously applied between the respective circuits during that time. The adhesion strength of the plating film after holding for 1000 hours in the above environment is 1.0 kgf / cm, the insulation resistance value between the circuits is 1 × 10 ¹² Ω, and the insulation resistance value between the circuits separated by the polyimide resin layer is It was 1 × 10 ¹² Ω.

From the above results, it can be said that the multilayer printed wiring board obtained by the above method has sufficient adhesion reliability and inter-circuit insulation reliability.

Example 3 The procedure of Example 1 was repeated except that the rubber-modified epoxy resin used had an average particle diameter of 10 μm and the content in the polyimide resin solution was 0.1% by volume with respect to the polyimide resin. A four-layer printed wiring board was obtained in the same procedure as in Example 1. The adhesion strength of the plating film of the obtained four-layer printed wiring board is 1.3 kgf / cm, the insulation resistance between the circuits is 1 × 10 ¹² Ω, and the insulation resistance between the circuits separated by the polyimide resin layer is 1 × 10 ¹² Ω. Further, the printed wiring board was allowed to stand still in a constant temperature and humidity chamber maintained at 85 ° C. under a relative humidity environment of 85%, and a voltage of 100 V was continuously applied between the respective circuits during that time. The adhesion strength of the plating film after holding for 1000 hours in the above environment is 1.0 kgf / cm, and the insulation resistance between circuits is 1 kgf / cm.
× 10 ¹¹ Ω, and the insulation resistance between circuits separated by the polyimide resin layer was 1 × 10 ¹¹ Ω.

From the above results, it can be said that the multilayer printed wiring board obtained by the above method has sufficient adhesion reliability and inter-circuit insulation reliability.

Example 4 A four-layer printed wiring board was obtained in the same manner as in Example 1, except that the thickness of the first polyimide resin film was changed to 3 μm. 4 obtained
The adhesion strength of the plating film on the printed wiring board is 1.5k
gf / cm, insulation resistance between circuits is 1 × 10 ¹³ Ω, insulation resistance between circuits separated by a polyimide resin layer is 1 ×
It was 10 ¹² Ω. Further, this printed wiring board is
The sample was allowed to stand still in a thermo-hygrostat kept at 85 ° C. under a relative humidity environment of 85%, and a voltage of 100 V was continuously applied between the above-mentioned circuits. The adhesion strength of the plating film after holding for 1000 hours in the above environment is 1.0 kgf / cm, the insulation resistance value between the circuits is 1 × 10 ¹² Ω, and the insulation resistance value between the circuits separated by the polyimide resin layer is It was 1 × 10 ¹¹ Ω.

From the above results, it can be said that the multilayer printed wiring board obtained by the above method has sufficient adhesion reliability and inter-circuit insulation reliability.

Comparative Example 1 A four-layer printed wiring board was obtained in the same procedure as in Example 1, except that a rubber-modified epoxy resin having an average particle diameter of less than 0.01 μm was used. . The adhesion strength of the plating film of the obtained four-layer printed wiring board is 0.7 kgf / cm, the insulation resistance between the circuits is 2 × 10 ¹³ Ω, and the insulation resistance between the circuits separated by the polyimide resin layer is 2 × 10 ¹³ Ω. Further, the printed wiring board was allowed to stand still in a constant temperature and humidity chamber maintained at 85 ° C. under a relative humidity environment of 85%, and a voltage of 100 V was continuously applied between the respective circuits during that time. The adhesion strength of the plating film after being held for 1000 hours in the above environment is 0.5 kgf / cm, and the insulation resistance between circuits is 5 × 10
The insulation resistance between the circuits separated by ¹² Ω and the polyimide resin layer was 1 × 10 ¹² Ω.

From the above results, the multilayer printed wiring board obtained by the above-mentioned production method did not have sufficient reliability in terms of the adhesion of the plating film.

Comparative Example 2 In Example 1, the rubber-modified epoxy resin had an average particle size of 15 μm and a maximum particle size of 30 μm.
A four-layer printed wiring board was obtained in the same manner as in Example 1 except that m was used. The adhesion strength of the plating film of the obtained four-layer printed wiring board is 1.4 kgf / cm, the insulation resistance between the circuits is 1 × 10 ⁸ Ω, and the insulation resistance between the circuits separated by the polyimide resin layer is 2 × 10 ⁷ Ω. Further, the printed wiring board was allowed to stand still in a constant temperature and humidity chamber maintained at 85 ° C. under a relative humidity environment of 85%, and a voltage of 100 V was continuously applied between the respective circuits during that time. The adhesion strength of the plating film after holding for 1000 hours in the above environment is 1.0 kgf / cm, and the insulation resistance between the circuits and the insulation resistance between the circuits separated by the polyimide resin layer are all 1 × 10Ω or less. Met.

From the above results, the multilayer printed wiring board obtained by the above-mentioned manufacturing method did not have sufficient reliability, particularly in terms of insulating properties.

[Comparative Example 3] In Example 1, the rubber was modified.
The content of epoxy resin is 0.0
The same procedure as in Example 1 was repeated except that the volume was 5% by volume.
A lint wiring board was obtained. Of the obtained four-layer printed wiring board
Adhesion strength of plating film is 0.8kgf / cm, between circuits
Insulation resistance value is 1 × 10¹³Ω, separated by polyimide resin layer
The insulation resistance between the circuits is 1 × 10¹³Ω.
Further, the printed wiring board is subjected to 85% relative humidity of 85%.
Leave it in a thermo-hygrostat kept under environmental conditions,
A voltage of 100 V was continuously applied between the circuits. And said
Adhesion strength of plating film after holding for 1000 hours in environment
The degree is 0.6kgf / cm, insulation resistance between circuits is 1 × 1
0¹²Ω, and between circuits separated by polyimide resin layer
Has an insulation resistance of 2 × 10 ¹²Ω.

From the above results, the multilayer printed wiring board obtained by the above-mentioned production method did not have sufficient reliability, particularly in terms of the adhesion strength of the plating film.

[Comparative Example 4] In Example 1, the rubber was modified.
The content of epoxy resin is 60 for polyimide resin.
% In the same manner as in Example 1 except that the
A wiring board was obtained. Of the resulting four-layer printed wiring board
The adhesion strength of the film is 1.5kgf / cm, insulation between circuits
The resistance value is 5 × 10¹¹Ω, separated by polyimide resin layer
The insulation resistance between the circuits is 1 × 10¹¹Ω. Further
The printed wiring board is placed at 85 ° C and 85% relative humidity.
Place the sample in a thermo-hygrostat kept below, during which time
A voltage of 100 V was continuously applied between the roads. And the environment
The adhesion strength of the plating film after holding for 1000 hours under
1.2kgf / cm, insulation resistance between circuits is 1 × 10
¹⁰Ω, and between circuits separated by polyimide resin layer
Insulation resistance value is 1 × 10 ⁶Ω.

From the above results, the multilayer printed wiring board obtained by the above-mentioned manufacturing method did not have sufficient reliability, particularly in terms of insulation.

Comparative Example 5 A four-layer printed wiring board was obtained in the same manner as in Example 1, except that the thickness of the first polyimide resin film was changed to 2 μm. 4 obtained
The adhesion strength of the plating film on the printed wiring board is 1.5k
gf / cm, insulation resistance between circuits is 1 × 10 ¹³ Ω, insulation resistance between circuits separated by a polyimide resin layer is 1 ×
It was 10 ¹¹ Ω. Further, this printed wiring board is
The sample was allowed to stand still in a thermo-hygrostat kept at 85 ° C. under a relative humidity environment of 85%, and a voltage of 100 V was continuously applied between the above-mentioned circuits. The adhesion strength of the plating film after holding for 1000 hours in the above environment is 1.0 kgf / cm, the insulation resistance value between the circuits is 1 × 10 ¹² Ω, and the insulation resistance value between the circuits separated by the polyimide resin layer is It was 1 × 10 ⁸ Ω.

From the above results, the multilayer printed wiring board obtained by the above-mentioned manufacturing method did not have sufficient reliability particularly in terms of insulation.

Comparative Example 6 A procedure was performed in the same manner as in Example 1 except that the first polyimide resin film contained 0.2% by volume of a spherical rubber-modified epoxy resin having an average particle size of 2 μm. A four-layer printed wiring board was obtained. The adhesion strength of the plating film of the obtained four-layer printed wiring board is 1.5 kg.
f / cm, insulation resistance between circuits is 1 × 10 ¹³ Ω, insulation resistance between circuits separated by polyimide resin layer is 1 × 1
0 ¹² Ω. The printed wiring board is heated to 85 ° C
At a constant temperature / humidity chamber maintained under a relative humidity environment of 85%, and a voltage of 100 V was continuously applied between the respective circuits during that time. The adhesion strength of the plating film after holding for 1000 hours in the above environment is 1.0 kgf / cm, the insulation resistance value between the circuits is 1 × 10 ¹² Ω, and the insulation resistance value between the circuits separated by the polyimide resin layer is It was 1 × 10 ⁹ Ω.

From the above results, the multilayer printed wiring board obtained by the above-mentioned manufacturing method did not have sufficient reliability, particularly in terms of insulating properties.

[0043]

As described above, according to the present invention, a multilayer printed wiring board having both high adhesion reliability and inter-circuit insulation reliability, which has been difficult in the past, can be obtained by a build-up method. This contributes sufficiently to high density, light weight, thin and small size of the wiring board.

Claims (4)

[Claims] A polyimide resin solution containing a solvent-soluble polyimide resin and fine particles more soluble in an oxidizing agent than the polyimide resin is applied to at least a part of the insulating substrate on which the conductive circuit is formed. Forming a polyimide resin layer, forming an insulating layer by removing a solvent from the polyimide resin layer, and forming a metal film by plating on the surface of the insulating layer, the method of manufacturing a multilayer printed wiring board, wherein the insulating substrate At least in part, the microparticles are added to 0.
A first polyimide resin film containing less than 1% by volume, and the fine particles having a thickness of 0.1 to 50 on the surface of the first polyimide resin film;
A method for manufacturing a multilayer printed wiring board, comprising: forming the insulating layer with a second polyimide resin film containing volume%. 2. The method according to claim 1, wherein the thickness of the first polyimide resin film is 3
2. The method for manufacturing a multilayer printed wiring board according to claim 1, wherein the thickness is not less than μm. 3. The method according to claim 1, wherein the fine particles contained in the second polyimide resin film are resin fine particles.
Or the method for producing a multilayer printed wiring board according to 2 above. 4. The multilayer print according to claim 1, wherein the average particle diameter of the fine particles contained in the second polyimide resin film is in a range of 0.01 to 10 μm. Manufacturing method of wiring board.