JPH1112504A - Composition for resin insulating layer onto which electroless plating is applicable and production of wiring board using the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain the subject composition useful for producing wiring board for high frequency circuit or fine electroconductive pattern, the wiring board allowing electroconductive layer to directly form on its resin insulating layer through fewer process steps, by including a polymer containing a chelate ligand of ion, etc., of the objective metal for plating. SOLUTION: This composition is obtained by introducing a chelate ligand of carboyxylic acid type represented by iminodiacetic acid or β-diketone type, which has an ability to capture either an ion of the plating metal applied onto the insulating layer or an ion (e.g. nickel, cobalt, etc., in case of copper plating) of the catalytic metal employed to accelerate precipitation of the plating metal, into a prepolymer qualified for the main component at a rate of at least one ligand to the repeating unit, and thus including the ligand. The objective composition can dispense with the burdensome roughing/catalyzing treatment preceding an electroless plating step which is indispensable to formation of buildup multilayered wiring board by the subtractive process. Also, the composition is useful for production of printed wiring board, etc.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a composition for a resin insulating layer which enables electroless plating, and a method for manufacturing a wiring board using the same. More specifically, the composition for a resin insulating layer of the present invention is a composition capable of forming an electroless plating film directly on a cured product of the composition, and the composition is a printed wiring board, particularly a printed wiring for a high-frequency circuit. It is particularly useful as an insulating material for substrates, high-density multilayer printed wiring boards, and the like.

[0002]

2. Description of the Related Art For example, as a high-density multilayer printed wiring board, there is a build-up multilayer wiring board formed by alternately stacking conductive circuit layers and resin insulating layers and connecting and conducting internal and external circuits. As a pattern forming method for the build-up wiring board, a subtractive method is currently mainstream. In this subtractive method, the copper foil of the copper-clad core substrate is etched into interior wiring, a liquid photosensitive resin is applied thereon, dried, exposed through a mask in contact with the resin surface, and developed. A pattern is formed, the patterned resin is cured by heating to form a resin insulating layer, and then a conductive circuit layer is formed on the resin insulating layer.
By repeating this series of steps, the required number of resin insulating layers and conductor circuit layers are stacked.

In order to form a conductor layer on a resin insulating layer,
Usually, a plating method is used. However, since the resin "insulating" layer is literally non-conductive, the surface of the resin layer must be made conductive in order to be plated thereon. When the surface of the resin layer is made conductive, a technique called catalysis is used.

The most widely used means for catalyzing the surface of a resin layer is to form a layer of metal palladium particles on the surface of the resin layer using tin chloride and palladium chloride. In this case, the surface of the resin layer is first eroded with an oxidizing agent such as permanganic acid to form a hole having a diameter of about 2 to 5 μm on the entire surface. This treatment is known as "roughening" of the resin layer surface. The hole formed by the roughening is a state in which the plating film enters into the resin when the plating enters later (anchor effect), and functions to increase the adhesion between the resin layer and the plating film. Next, a palladium nucleus serving as a catalyst for electroless plating is deposited on the roughened surface to catalyze the surface of the resin layer. The resin layer whose surface has been catalyzed in this way is immersed in an electroless plating solution to form a thin conductive film layer. Thereafter, in order to form a conductor layer having a desired thickness, electroplating is performed this time to complete the formation of the conductor layer.

[0005] Such a method of catalyzing the plating of a resin insulating layer has been established and is generally suitable.

[0006]

However, such a method of forming a conductive layer by roughening and catalyzing the resin insulating layer and plating the resin insulating layer is disadvantageous in that it requires a multi-step process. In addition, according to such a conventional method, a hole having a diameter of 2 to 5 μm must be formed on the entire surface of the resin layer in order to obtain an appropriate adhesion between the resin insulating layer and the conductor layer.
This becomes effective as a resistor particularly when the signal becomes a high frequency signal of GHz or more, and thus causes a conductor loss as a transmission line in a high frequency circuit. Further, the diameter of the hole formed in the resin layer surface of 2 to 5 μm may hinder the miniaturization of the conductor pattern formed on the resin layer. Therefore, the conventional subtractive method known to be able to manufacture a multilayer wiring board at low cost is as follows.
The method requires many steps and is troublesome, cannot be applied to a wiring board for a high-frequency circuit, and cannot be adapted to miniaturization of a conductor pattern.

[0007] The present invention provides a direct electroless process which enables a conductor layer to be formed on a resin insulating layer in a small number of steps, and enables the manufacture of a wiring board for a high-frequency circuit or a wiring board having a fine conductor pattern. It is an object of the present invention to provide a composition for a resin insulating layer that can be plated, and to provide a method for manufacturing a wiring board using the composition.

[0008]

According to the present invention, a composition for a resin insulating layer which can be directly electrolessly plated is formed of a metal ion to be plated on the formed insulating layer, or a metal of the metal to be plated. It is characterized by containing a polymer compound containing a chelate ligand capable of capturing ions of a metal which serves as a catalyst for promoting the precipitation. The composition may be a photosensitive or thermosetting composition, or may be a composition having both photosensitive and thermosetting properties.

A method of manufacturing a wiring board according to the present invention is a method of manufacturing a wiring board by forming a resin insulating layer of a resin material on a substrate to be processed and forming a conductive circuit layer thereon by plating. A polymer compound containing a chelate ligand capable of capturing ions of the metal to be plated on the insulating layer formed, or ions of the metal serving as a catalyst for promoting the deposition of the metal to be plated. A film is formed on a substrate to be processed using the composition for a resin insulating layer that has been formed, and in a state where the film is in an uncured or semi-cured state, the chelate ligand on the film surface is supplemented with ions of the above metal. Then, the film is cured to form an insulating layer, and plating is deposited on the insulating layer by electroless plating.

[0010]

BEST MODE FOR CARRYING OUT THE INVENTION The composition for a resin insulating layer of the present invention comprises:
This enables a desired metal film to be formed by electroless plating directly on an insulating layer formed by using the same. Thus, a plating having a required thickness can be deposited by electroplating on the metal film formed by electroless plating.

A polymer compound containing a chelate ligand capable of capturing ions of a metal to be plated on the formed insulating layer or ions of a metal serving as a catalyst for promoting the deposition of the metal to be plated is The chelating ligand captures ions of a given metal, thereby enabling the metal to be plated to be deposited directly on the insulating layer by electroless plating.
Whether the chelating ligand directly captures the ions of the metal to be plated or the metal ions that act as catalysts to promote the deposition of the metal to be plated, The metal to be deposited continues to be deposited with the metal captured by the chelating ligand as a nucleus to form a film. Therefore, it is desirable that this polymer compound is a main component of the resin composition of the present invention for forming an insulating layer.

A typical example of a metal used for plating is copper (Cu).
It is. However, the metal used for plating is of course not limited to this. In the present invention, the polymer compound, which is a main component of the composition for forming the insulating layer, contains a chelate ligand having an ability to capture ions of the metal used in the plating, so that after forming the insulating layer, It is possible to perform direct plating by electroless plating on the insulating layer without having to roughen or catalyze the surface as in the related art.

[0013] Depending on the type of the polymer compound used as the insulating layer material,
Is a chelating ligand that can be contained in it
Does not necessarily supplement the ions of the metal
Not always. In such a case,
A metal that acts as a catalyst to promote the deposition of the metal to be plated
Use a chelating ligand capable of capturing the ions
be able to. If the metal to be plated is copper,
As metal ions serving as effective catalysts for promoting the precipitation of
i²⁺, Co²⁺, Sn²⁺, Pd²⁺, Ag⁺, Au ⁺Etc.
Can be mentioned.

The chelating ligand is required to have the ability to capture ions of a metal to be plated or ions of a metal serving as a catalyst, and further have the properties of a resin as an insulating material, such as chemical resistance and heat resistance. It must be as small as possible to the extent possible, or the resolution for patterning the insulating layer. As an example, for a composition that can be developed with an alkaline aqueous solution, carboxylic acid type represented by iminodiacetic acid, azo type, polyamine or polyimine type, alcoholic or phenolic hydroxyl type, β-diketone Ligands such as types are hydrophilic,
Deemed appropriate. Needless to say, ligands that can be introduced into the polymer compound are not limited to these.

As described above, the chelating ligand is desirably introduced into the polymer compound which is the main component of the composition, and more specifically, the prepolymer which is the main component of the composition of the present invention. It is appropriate because it is introduced to When it is difficult to introduce into the prepolymer of the main component or there is a possibility that the properties of the resin may be significantly impaired by the introduction, a prepolymer of another polymer component may be used. The prepolymer into which the chelating ligand has been introduced desirably contains at least one chelating ligand in its repeating unit. It is also possible to use a copolymer into which a chelating ligand has been introduced, in which case the chelating ligand is introduced into at least one of the plurality of constitutional repeating units.

The composition of the present invention comprises, in addition to the above-mentioned polymer compound (prepolymer) containing a chelating ligand, a curing agent for accelerating the curing, a polymerization initiator for initiating the curing reaction, and the like. And other components generally used in a resin composition used to form an insulating layer on a substrate to be processed.
The polymeric compounds used to form the insulating layer, as well as the curing agents, initiators and other components are well known in the art and need not be described at length here.

The metal ions are captured by the chelating ligand on the surface of the film formed on the substrate to be treated using the composition of the present invention, because the polymer compound of the resin component contained in the composition is completely cured. It must be done before, ie while the formed coating is in an uncured or semi-cured state.
The reason is that the formed film is cross-linked by light or heat,
This is because, as the polymerization reaction proceeds, the amount of metal ions adsorbed to the chelating ligand on the film surface is significantly reduced.

Therefore, the capture (complex formation) of metal ions to the chelate ligand can be carried out by using the composition for a resin insulating layer of the present invention in the case of a liquid solvent-type composition. It is necessary to apply after drying for the purpose of coating on the substrate) and removing the solvent, or after forming a pattern by exposure and development, and when the composition is a liquid and non-solvent type,
It must be performed after application on the substrate or after pattern formation by exposure and development, and when the composition is a dry film, after lamination on the substrate or after pattern formation by exposure and development is necessary. At this time, the curing of the resin composition (mainly heat curing in the case of a liquid state, mainly light curing in the case of a dry film) does not prevent progress to some extent, but the degree of curing on the film surface is not limited. In this case, it is preferable that the content is 50% or less.

Any method may be employed to cause metal ions to be adsorbed on the surface of the film formed on the substrate to be treated and to be captured by the chelating ligand. Generally, the target substrate on which a film is formed is immersed in an aqueous solution adjusted to a pH suitable for forming a chelate bond by dissolving a target metal ion until the complex equilibrium is reached. The immersion time varies depending on the chelate ligand contained in the polymer compound and the degree of curing of the film surface, but is generally several minutes to several tens of minutes.

After the surface of the film captures ions of the metal to be electrolessly plated or a metal ion serving as a catalyst by forming a chelate bond, after the film is sufficiently cured by light or heat, it is subjected to an ordinary method. A conductive film layer can be formed by the electroless plating bath. A plating film that grows with the metal trapped as a complex on the surface of the insulating layer has a sufficiently strong adhesion to the insulating layer, and therefore has sufficient adhesion without the need for roughening and catalyzing the surface of the insulating layer. It becomes possible to form an electroless plating film provided with. After forming the conductive film layer by electroless plating in this manner, a conductor film having a desired thickness can be easily formed by ordinary electroplating.

As described above, according to the present invention, a metal film can be formed directly on an insulating layer by electroless plating without roughening and catalyzing the surface of the resin insulating layer.
It is possible to manufacture a wiring board for a high-frequency circuit or a wiring board with a fine conductor pattern. However, wiring boards that can be manufactured by applying the present invention are not limited thereto, and are manufactured by a method involving formation of a resin insulating layer and formation of a conductor layer by plating, including, for example, printed wiring boards and motherboards. In addition, any wiring board is a target.

[0022]

EXAMPLES Next, examples will be given to explain the present invention more specifically. Note that the present invention is not limited to this. In these examples, the present invention was applied to a photosensitive insulating material for build-up.

Example 1 50 parts by weight of a novolak type phenol resin containing one iminodiacetate group per repeating unit (this resin was obtained from Kanto Chemical Co., Ltd.), and a cresol novolak type epoxy resin (manufactured by Toto Kasei Co., Ltd.) ) To 30
Parts by weight, 20 parts by weight of pentaerythritol tetraacrylate (photoinitiator), 2 parts by weight of Irgacure 907 (curing agent manufactured by Ciba Geigy), 1 part by weight of triphenylphosphine (thermal polymerization initiator), and ethyl celloacetate 10 parts by weight of (diluent) and 1 part by weight of cyanine green (colorant) were weighed and kneaded by a roll mill to prepare a build-up insulating material composition. Next, this was applied to a thickness of 30 μm on a copper foil by blade coating to form a film.

Thereafter, the film was dried at 80 ° C. for 20 minutes, and exposed to ultraviolet light having a light intensity of 365 mW / cm ² at a wavelength of 365 nm in a desired pattern for 30 seconds to semi-cure the film. FIG. 1 is a diagram conceptually illustrating this processing. Subsequently, spray development (pressure 1 kg / cm ² , 60 seconds) was performed with a 2% aqueous solution of sodium carbonate at a liquid temperature of 30 ° C. The thus patterned film is immersed in an aqueous solution containing 1 mol / l of Cu ²⁺ ions at a pH of about 5.5 for 1 hour to allow the chelating ligand on the surface to capture the Cu ²⁺ ions, and furthermore, The surface was irradiated with the above-mentioned ultraviolet ray at 1000 mJ to be photo-cured. FIG. 2 is a diagram conceptually illustrating this processing.
Subsequently, the film was heated and cured at 180 ° C. for 1 hour to form an insulating layer. FIG. 3 is a diagram conceptually illustrating this processing.

The copper foil having the insulating layer thus formed is immersed in a cleaner conditioner 211 solution (45 ° C.) manufactured by Shipley Co., Ltd. for 5 minutes to perform a degreasing treatment, and 328 L of an electroless copper plating solution cupposit copper mix manufactured by the company.
When immersed in the solution for 30 minutes at room temperature, formation of a copper plating film was confirmed.

[Example 2] The chelating ligand introduced into the novolak type phenolic resin used in Example 1 was of the β-diketone type (the resin incorporating the chelating ligand was also obtained from Kanto Chemical Co.) Example 1 except that
Was repeated, formation of a copper plating film was similarly observed.

[0027]

As described above, when the composition of the present invention is used, a complicated roughening / catalyzing treatment prior to the electroless plating, which is indispensable in the conventional subtractive method, can be omitted and the insulating layer can be formed on the insulating layer. It is possible to form a metal film directly by electroless plating. In addition, by omitting the roughening of the insulating layer surface in this way, a wiring board for a high-frequency circuit,
It is possible to manufacture a wiring board having a fine conductor pattern.

[Brief description of the drawings]

FIG. 1 is a first diagram conceptually illustrating a process according to a first embodiment.

FIG. 2 is a second diagram conceptually illustrating the processing of the first embodiment.

FIG. 3 is a third diagram conceptually illustrating the processing of the first embodiment.

Continued on the front page (51) Int.Cl. ⁶ Identification code FI H05K 3/18 H05K 3/18 EB

Claims (10)

[Claims] 1. A chelating ligand capable of capturing ions of a metal to be plated on a formed insulating layer or ions of a metal serving as a catalyst for promoting the deposition of the metal to be plated. A composition for a resin insulating layer, comprising a polymer compound. 2. The composition according to claim 1, which is a photosensitive or thermosetting composition, or a composition having both photosensitive and thermosetting properties. 3. The composition according to claim 1, wherein the metal to be plated is copper. 4. The composition according to claim 3, wherein the metal serving as a catalyst for accelerating the deposition of the metal to be plated is nickel, cobalt, tin, palladium, silver or gold. 5. The chelating ligand according to claim 1, wherein the chelating ligand is a carboxylic acid type, azo type, polyamine type, polyimine type, alcoholic or phenolic hydroxyl type, or β-diketone type ligand. The composition according to any one of the preceding claims. 6. A method of manufacturing a wiring board by forming a resin insulating layer with a resin material on a substrate to be processed and forming a conductive circuit layer by plating on the resin insulating layer, wherein the plating is performed on the formed insulating layer. Composition for a resin insulation layer containing a polymer compound containing a chelate ligand capable of capturing ions of a metal to be formed or a metal ion serving as a catalyst for promoting the deposition of the metal to be plated Using things
A film is formed on a substrate to be processed, and in a state where the film is in an uncured or semi-cured state, the chelate ligand on the film surface is trapped by ions of the above metal, and then the film is cured to form an insulating layer. And depositing plating on the insulating layer by electroless plating. 7. The method according to claim 6, wherein the curing of the film is performed by crosslinking and polymerization by one or both of light and heat. 8. The method according to claim 6, wherein the metal to be plated is copper. 9. The method according to claim 8, wherein the metal serving as a catalyst for promoting the deposition of the metal to be plated is nickel, cobalt, tin, palladium, silver or gold. 10. The chelating ligand is a carboxylic acid type,
The method according to any one of claims 6 to 9, wherein the ligand is a ligand of an azo type, a polyamine type, a polyimine type, an alcoholic or phenolic hydroxyl type, or a β-diketone type.