JP2832181B2 - Photosensitive resin insulation - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a photosensitive resin insulating material, and more particularly to an insulating material useful for a multilayer printed wiring board having a conductor circuit composed of a plurality of electrically insulated electroless plating films. It is about.

[0002]

2. Description of the Related Art In recent years, with the advance of electronic technology, electronic devices such as large-sized computers have been increased in density or speed of arithmetic functions. As a result, multilayer printed wiring boards, in which wiring circuits are formed in multiple layers for the purpose of increasing the density of printed wiring boards, have been spotlighted.
Conventionally, a typical multilayer printed wiring board is, for example, a multilayer printed wiring board in which a plurality of circuit boards on which an internal circuit is formed are laminated and pressed using a prepreg as an insulating layer, and then each of the internal circuits is connected and conductive through through holes. It was a typical thing. However, in such a multilayer printed wiring board, since a plurality of internal circuits are connected and conducted through through holes, the wiring circuit becomes too complicated to realize high density or high speed. there were.

As a multilayer printed wiring board capable of overcoming such a problem, recently, a multilayer printed wiring board in which conductive circuits and organic insulating films are alternately built up has been developed. This multilayer printed wiring board is suitable for ultra-high density and high speed, but has a drawback in that it is difficult to form an electroless plating film on an organic insulating film with high reliability. For this reason, in such a multilayer printed wiring board, a conductor circuit is formed by a PVD method such as vapor deposition or sputtering or a combination method of the PVD method and electroless plating. The forming method has the disadvantages of poor productivity and high cost.

[0004]

DISCLOSURE OF THE INVENTION The present inventors have conducted various studies for the purpose of solving the drawbacks of the conventional multilayer printed wiring board as described above, and have previously disclosed in Japanese Patent Application Laid-Open No. 63-126297. The invention relating to a printed wiring board and an insulating material used for the same has been proposed. However, the insulating material proposed prior to the present invention, if there is no significant difference in the solubility of the particulate material and the matrix resin in a specific chemical solution, the anchor is likely to be unclear, as a result, the plating film The problem remains that the adhesion does not increase.
An object of the present invention is to solve the problem of the insulating material for a multilayer printed wiring board previously proposed by the present inventors, and to easily provide a multilayer printed wiring board having an electroless plated film formed with high reliability. Another object of the present invention is to provide an insulating material for manufacturing at low cost.

[0005]

The problem of the insulating material according to the prior invention proposed by the present inventors prior to the present invention is that the photosensitive resin as the insulating layer contains a heat-resistant resin. It has been found that the problem can be solved by including agglomerated particles obtained by aggregating the powder. That is, the present invention relates to a photosensitive resin insulating material comprising a photosensitive resin that is hardly soluble in an aqueous solution of an oxidizing agent and heat-resistant particles that are soluble in the aqueous solution of the oxidizing agent.
The heat-resistant particles that are soluble in the aqueous solution of the above are obtained by agglomerating a heat-resistant resin fine powder having an average particle size of 2 μm or less to form an average particle size of 2 μm.
A photosensitive resin insulating material comprising aggregated particles having a size of about 10 μm. In the photosensitive resin insulating material, the heat-resistant particles are blended in an amount of 5 to 350 parts by weight based on 100 parts by weight of the solid content of the photosensitive resin which is hardly soluble in an aqueous solution of an oxidizing agent. Hereinafter, "aqueous solution of oxidizing agent"
Is simply abbreviated as “oxidizing agent”. In the present invention,
Is a photosensitive resin insulating material and a photosensitive insulating resin composition
That is.

[0006]

BEST MODE FOR CARRYING OUT THE INVENTION Hereinafter, the present invention will be described in detail.
The photosensitive resin insulating material according to the present invention is suitably used as a resin insulating layer of a multilayer printed wiring board having a conductor circuit composed of a plurality of electroless plated films electrically insulated by a resin insulating layer composed of a heat-resistant resin. Can be Hereinafter, the configuration of the present invention will be described in detail based on an example in which such a photosensitive resin insulating material is used as an insulating layer of a multilayer printed wiring board.

[0007] The resin insulating layer for a multilayer printed wiring board needs to have excellent adhesion to an electroless plating film. In a hardly soluble heat-resistant resin, a heat-resistant resin fine powder having an average particle size of 2 μm or less has an average particle size of 2 to 10 μm.
The heat-resistant particles are composed of aggregated particles formed by aggregating so as to obtain m (however, the heat-resistant particles are soluble in an oxidizing agent). The surface of the resin insulating layer on which the electroless plating film is formed is
The heat-resistant particles have a concave portion formed as a result of being dissolved by an oxidizing agent, and the concave portion serves as an anchor of the electroless plating film.

That is, in the photosensitive resin insulating layer according to the present invention, the photosensitive resin constituting the matrix and the heat-resistant resin particles and fine powder dispersed in the resin have high solubility in an oxidizing agent. Due to the difference, when these are treated with an oxidizing agent, the soluble heat-resistant resin particles dispersed on the surface portion of the photosensitive resin matrix are mainly dissolved and removed, thereby forming a clear anchor, and forming a resin insulating material. The surface of the layer is uniformly roughened. As a result, high adhesion strength and reliability to the electroless plating film can be obtained.

The heat-resistant particles dispersed in the photosensitive resin insulating material according to the present invention are obtained by aggregating heat-resistant resin fine powder having an average particle diameter of 2 μm or less so that the average particle diameter becomes 2 to 10 μm. Aggregated particles. The reason for using such particles is that by using these particles or a mixture as heat-resistant particles, the shape of the formed anchor can be made extremely complicated.

Here, among the heat-resistant particles, the size of the aggregated particles having an average particle size of 2 to 10 μm is used if the average particle size is larger than 10 μm due to the oxidation treatment. The density of the anchor formed by dissolution removal is small and tends to be non-uniform. As a result, the adhesion strength of the plating film is deteriorated, the reliability of the product is reduced, and the unevenness of the surface of the adhesive layer becomes more intense than necessary, and it becomes difficult to obtain a fine pattern of the conductor. This is because inconvenience is likely to occur in mounting. On the other hand, if the average particle size is smaller than 2 μm, the anchor tends to be unclear. More preferably, those having a size of 3 to 8 μm are suitable.

On the other hand, it is necessary that the size of the heat-resistant resin fine powder constituting the aggregated particles is 2 μm or less in average particle size. The reason for this is that if it is larger than 2 μm, the anchor effect is reduced and the adhesion strength of the plating film is deteriorated. More preferably, the size is 0.8 μm or less. The particle size of the aggregated particles is advantageously at least twice the particle size of the heat-resistant resin fine powder constituting the aggregated particles.

The heat-resistant particles are resins having excellent heat resistance and electrical insulation properties and exhibiting properties stable to chemicals other than an oxidizing agent. It is necessary to use a resin that is hardly soluble in water but soluble in an oxidizing agent. As a resin constituting such heat resistant particles, for example, at least one selected from an epoxy resin, a polyester resin, and a bismaleimide-triazine resin is used. Among them, the epoxy resin is excellent in characteristics and is most suitable. As the oxidizing agent, chromate, chromate, permanganate, ozone and the like are used.

The photosensitive resin which is hardly soluble in an oxidizing agent is excellent in heat resistance, electrical insulation, chemical stability, and adhesiveness. For example, at least one selected from an epoxy resin, an epoxy-modified polyimide resin, a polyimide resin, and a phenol resin is used. The reason why this photosensitive resin is used as a matrix constituent material is that it is advantageous to easily form via holes for connecting conductor layers by exposing a predetermined portion to light and then developing and etching. In addition, even if the resin constituting the heat-resistant particles and the heat-resistant resin constituting the matrix are the same kind of resin, for example, an epoxy resin, the use of a resin having a difference in solubility with respect to an oxidizing agent will provide the present invention. The effect of can be exhibited.

The amount of the heat-resistant particles to be added to the heat-resistant resin constituting the matrix is preferably in the range of 2 to 350 parts by weight based on 100 parts by weight of the heat-resistant resin constituting the matrix. It is preferable that the content be in the range of 5 to 200 parts by weight in order to increase the adhesion strength between the resin insulating layer and the electroless plating film. If the amount of the heat-resistant particles is less than 2 parts by weight, the density of the anchor formed by dissolution and removal is low, and a sufficient adhesion strength between the resin insulating layer and the electroless plating film cannot be obtained. On the other hand, if it exceeds 350 parts by weight, most of the surface of the resin insulating layer is dissolved and removed, so that it is difficult to form a clear anchor.

The heat-resistant resin particles and fine powder soluble in the oxidizing agent are both constituted by a curing treatment. The heat-resistant resin constituting the heat-resistant particles and fine powder is limited to the hardened resin. If the hardened resin is not used, the heat-resistant resin liquid forming the matrix or the heat-resistant resin forming the matrix is used. When the heat-resistant resin is added to a solution in which the heat-resistant resin is dissolved using a solvent, the heat-resistant resin constituting the heat-resistant particles also dissolves in the heat-resistant resin liquid or the solution, and exhibits the function as the heat-resistant particles. It becomes impossible.

The heat-resistant resin particles and the fine powder constituting the heat-resistant particles are, for example, heat-cured and then pulverized using a jet mill or a freeze-pulverizer, or before hardening. It is manufactured by spray-drying a heat-resistant resin solution and then curing, or by classifying particles obtained by adding an aqueous solution curing agent to an uncured heat-resistant resin emulsion and stirring, using an air classifier or the like. . In addition, as a method of curing the heat-resistant resin constituting the heat-resistant particles, there is a method of curing by heating or a method of curing by adding a catalyst. Among them, a method of curing by heating is practical. .

Among the heat-resistant particles, the heat-resistant resin fine powder may be formed into agglomerated particles by, for example, simply heating the heat-resistant resin fine powder with a hot air drier or using various binders. Is added, mixed and dried to cause agglomeration. Then, it is advantageous that the product is crushed using a ball mill, an ultrasonic disperser, or the like, and further classified by an air classifier or the like to produce the product. The shape of the heat-resistant particles obtained in this way has not only a spherical shape but also various complicated shapes, and therefore, the shape of the anchor formed thereby has a correspondingly complicated shape. It works effectively to improve the adhesion strength of the plating film such as the pull strength.

The heat-resistant particles produced as described above are:
A mixed liquid is produced by adding a photosensitive resin liquid for forming a matrix or a solution in which the photosensitive resin for forming the matrix is dissolved using a solvent and uniformly dispersing the same. As the photosensitive resin liquid to which the heat-resistant particles are added, a photosensitive resin liquid containing no solvent can be used as it is, and a photosensitive resin liquid obtained by dissolving a photosensitive resin in a solvent is also low. Because of the viscosity, the heat-resistant particles can be easily dispersed uniformly, and can be applied to a substrate having a conductor layer easily, so that it can be advantageously used. As a solvent used to dissolve this photosensitive resin, a normal solvent,
For example, methyl ethyl ketone, methyl cellosolve, ethyl cellosolve, butyl carbitol, butyl cellulose, tetralin, dimethylformaldehyde, normal methylpyrrolidone and the like can be used.

The preferred thickness of the resin insulating layer for a printed wiring board formed using the insulating material according to the present invention is usually 20 to
Although it is about 100 μm, it can be made thicker when a particularly high insulating property is required.

The resin insulating layer is usually provided with a via hole for connecting the conductor layers. As a method of forming the via hole, a method of developing and etching after exposing a predetermined portion is preferable, but a method of forming a via hole by laser processing can also be applied. The method of forming via holes by laser processing can be applied before or after roughening the surface of the resin insulating layer.

[0021]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment for manufacturing a multilayer printed wiring board using the photosensitive resin insulating material according to the present invention will be described below. (Example 1) (1) A photosensitive dry film (manufactured by DuPont, trade name: Liston 1051) is laminated on a glass epoxy copper-clad laminate (manufactured by Toshiba Chemical, trade name: Toshiba Tecolite MEL-4), and a desired conductor is formed. The image was printed by exposing to ultraviolet light through a mask film on which a circuit pattern was drawn. Then, development was carried out with 1-1-1-trichloroethane, and copper in the non-conductor portion was removed using a cupric chloride etching solution, and then the dry film was peeled off with methylene chloride. As a result, a wiring board having the first-layer conductor circuit 1 including a plurality of conductor patterns on the substrate 2 was formed. (2) Epoxy resin particles (Toray Pearl-
B, average particle size 0.5 μm) was charged into a hot air dryer,
Heat treatment was performed at 3 ° C. for 3 hours to cause cohesive bonding. The cohesively bonded epoxy resin particles were dispersed in acetone, crushed in a ball mill for 5 hours, and then classified using an air classifier to prepare coagulated particles. The aggregated particles had an average particle size of about 3.5 μm, and about 68% by weight was in a range of ± 2 μm around the average particle size. (3) 75% acrylate 50 of cresol novolak type epoxy resin (manufactured by Nippon Kayaku, trade name: EOCN-103 S)
50 parts by weight, bisphenol A type epoxy resin (manufactured by Dow Chemical, trade name: DER661), 25 parts by weight of dipentaerythritol hexaacrylate, benzyl alkyl ketal (manufactured by Ciba Geigy, trade name: Irgacure 651) After mixing 5 parts by weight, 6 parts by weight of imidazole (manufactured by Shikoku Chemicals, trade name: 2P4MHZ) and 50 parts by weight of the agglomerated particles prepared in the above (2), while adding butyl cellosolve, the viscosity was 250 cp with a homodisper stirrer. , And kneaded with three rollers to prepare a solution of the photosensitive resin composition. (4) On the wiring board (substrate 2) created in (1) above,
The solution of the photosensitive resin composition prepared in the above was applied using a knife coater, allowed to stand in a horizontal state for 20 minutes, and then dried at 70 ° C. to form a photosensitive resin insulating layer 3 having a thickness of about 50 μm. (5) A photomask film having a black circle of 100 μmφ printed thereon was brought into close contact with the wiring board subjected to the treatment of the above (4), and was exposed at 500 mJ / cm ² with an ultrahigh pressure mercury lamp. This was subjected to ultrasonic development with a chlorocene solution to form a 100 μmφ via hole on the wiring board. The wiring board is exposed to an ultra-high pressure mercury lamp at about 3000 mJ / cm ² , and further subjected to a heat treatment at 100 ° C. for 1 hour and then at 150 ° C. for 10 hours to form openings having excellent dimensional accuracy equivalent to a photomask film. To form a resin insulating layer 3. (6) The wiring board prepared in (5) is replaced with chromic acid (Cr ₂ O ₃ ).
Immerse in a 500g / l aqueous solution of oxidizing agent at 70 ° C for 15 minutes,
After roughening the surface of the interlayer resin insulating layer as shown in FIG. 1 (b) at 4 (a) in an enlarged scale, a neutralizing solution (PN, manufactured by Shipley Co., Ltd.) is used.
950) and washed with water. A substrate with a roughened resin insulation layer is coated with a palladium catalyst
44) was applied to activate the surface of the insulating layer, and immersed in an electroless copper plating solution having the composition shown in Table 1 for 11 hours to perform electroless copper plating with a plating film thickness of 25 μm.

[0022]

[Table 1] (7) After repeating the steps (1) to (6) twice, and further performing the step (1), the wiring layer has four layers, that is, the second-layer conductive circuit 5, A build-up multilayer wiring board having the three-layer conductive circuit 6 and the fourth-layer conductive circuit 7 was prepared.

The adhesion strength between the insulating layer and the electroless plating film of the multilayer printed wiring board manufactured as described above was measured according to JIS-C.
The measurement was carried out according to the method of -6481, and the results are shown in Table 2.

[Table 2]

[0024]

As described above, when the photosensitive resin insulating material according to the present invention is applied to a multilayer printed wiring board, the adhesiveness between the conductor circuit formed of an electroless plating film and the like and the insulating layer is extremely excellent. The resulting resin insulation layer can be obtained.

[Brief description of the drawings]

FIGS. 1 (a) to 1 (d) are diagrams showing manufacturing steps of a build-up multilayer wiring according to a first embodiment, respectively.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 First layer conductor circuit 2 Substrate 3 Interlayer insulating layer 4 (a) Enlarged sectional view of roughened portion 5 Second layer conductor circuit 6 Third layer conductor circuit 7 Fourth layer conductor circuit

Claims (2)

(57) [Claims] 1. A photosensitive resin insulating material comprising a photosensitive resin which is hardly soluble in an aqueous solution of an oxidizing agent and heat-resistant particles which are soluble in an aqueous solution of an oxidizing agent . The heat-resistant particles soluble in an aqueous solution are made of agglomerated particles obtained by aggregating heat-resistant resin fine powder having an average particle diameter of 2 μm or less to have an average particle diameter of 2 to 10 μm. Wood. 2. The heat-resistant particles are mixed in an amount of 5 to 350 parts by weight based on 100 parts by weight of the solid content of the photosensitive resin which is hardly soluble in an aqueous solution of an oxidizing agent. Of photosensitive resin insulation.