JP2017053014A - Electroless plating pretreatment agent, conductive pattern forming substrate, and production method thereof - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an electroless plating pretreatment agent, a conductive pattern forming substrate, and a production method thereof.SOLUTION: In a production method of a conductive pattern forming substrate, pattern formation is performed by photolithography on an insulating substrate of plastic or glass, and its structure is coated with sol comprising a tetravalent tin compound as electroless plating pretreatment liquid, then, a resist on the substrate is removed, and a pattern comprising the electroless plating pretreatment agent is produced, thereafter, electroless plating pretreatment is performed, to thereby form the conductive pattern.SELECTED DRAWING: Figure 1

Description

  The present invention relates to a conductive pattern forming substrate using photolithography and a subsequent plating method and a manufacturing method thereof.

  The method of manufacturing a conductive pattern forming substrate such as a printed wiring board is to create a copper thin film by copper foil or copper plating on an insulating base material, and then sensitize and develop by photolithography, and then draw a wiring pattern. A conductive pattern is formed.

  In addition, development has been made on materials such as transparent conductive films and electromagnetic wave shields using conductive patterns. These are applied as a transparent conductive film or an electromagnetic wave shield by producing a thin metal pattern on glass by sputtering or the like and controlling the width of the mesh pitch.

  As a method for producing a conductive pattern of a printed wiring board, a method called “subtract method” is often used. In this method, an etching resist is formed by photolithography, the exposed copper film is removed using a solution such as ferric chloride, and then the remaining resist is peeled to obtain a conductive pattern. In this method, the line width / interval of pattern wiring (hereinafter referred to as L / S) can be up to about 30/30 (μm), which is the most common method for manufacturing a printed wiring board.

  On the other hand, IC package substrates and the like use finer wiring, and a method called “semi-additive method” is used for these. This is because a seed layer made of a thin copper film is formed on a substrate by sputtering or electroless copper plating, a plating resist is formed by photolithography, pattern plating is performed, and then the resist is peeled off and the unplated portion seed layer is formed. Etching is performed to form a conductive pattern.

  The semi-additive method requires a smaller amount of etching processing than the subtract method, and therefore requires less circuit portion loss and can form a finer circuit. If the semi-additive method is used, L / S can be up to about 5/5 (μm).

  These materials are expected to require further fine wiring as the electronic components are miniaturized and the functions of the materials are increased.

  In order to solve these problems, a method of forming a conductive pattern by screen printing or an ink jet method using ink containing metal nanoparticles has attracted attention. (Reference 1)

  In the pattern formation method using metal nanoparticles, a heat treatment at 200 to 300 ° C. is necessary as a post-process to fix the patterned metal. There are problems such as having to manage strictly. Moreover, when the baking process is not performed, it is difficult to obtain a conductive pattern with low electrical resistance.

  In the ink jet system, in addition to the ejection necessary for printing, cleaning for nozzle cleaning of the ink head is necessary, and a large amount of ink used at that time is discarded. For this reason, although production of fine wiring can be expected, many problems still remain in the mass productivity.

  Among the semi-additive method that is advantageous for mass production of microcircuits, the etching of the seed layer is one of the very important processes for forming the narrow pitch circuit. There is a problem of short circuit, and if the etching is excessive, there is a risk that the resistance increases due to the reduction in the line width due to etching erosion to the circuit portion, and the disconnection occurs due to excessive erosion.

  Furthermore, there is a “full additive method” as a method for producing a fine pattern, but this method also requires an etching process for an ultrathin copper foil, and the same problem remains.

  Other manufacturing methods include “sputtering method” and “chemical vapor deposition method”, but this method has a problem that a dedicated apparatus is expensive and it is difficult to apply to a large area material. ing.

Surface technology, vol.61, No.12

  The present invention has been made in view of the above circumstances, and a method of manufacturing a fine conductive pattern forming substrate by a method that does not require an etching process of a seed layer, applying a process of a conventional semi-additive method, and its The purpose is to provide material.

As a result of intensive studies in order to solve the above problems, the present inventor has solved the above problems by the following method.
The present invention is as follows.

  In order to solve this problem, the invention according to claim 1 is an insulating base material and a conductive layer formed on the insulating base material, and an intermediate layer is provided between the base material and the conductive layer. A conductive pattern forming substrate, wherein a film made of a tin compound is formed.

  The invention according to claim 2 forms a pattern by photolithography on a substrate, coats the structure with an electroless plating pretreatment agent, and forms a conductive pattern by electroless plating after removing the resist. This is a method for producing a conductive pattern-formed substrate.

  Invention of Claim 3 is a manufacturing method of the electroconductive pattern formation board | substrate of Claim 2 whose electroless-plating pretreatment agent is sol which consists of a tetravalent tin compound.

  The invention according to claim 4 is the conductive pattern forming substrate according to claim 2, wherein the pretreatment agent for electroless plating is a mixed sol of a tetravalent tin compound and one or both of a palladium complex ion and a silver complex ion. It is a manufacturing method.

  Invention of Claim 5 is a manufacturing method of the electroconductive pattern formation board | substrate of Claim 3 immersed in the aqueous solution of one or both of palladium complex ion or silver complex ion after electroless-plating pretreatment agent coating. .

The invention according to claim 6 is the method for producing a conductive pattern substrate according to any one of claims 2 to 5, wherein the reduction treatment is performed immediately before the electroless plating.

  In the conductive pattern forming substrate and the manufacturing method thereof according to the present invention, the etching of the seed layer, which is performed by the conventional method, is not required, so that the circuit portion loss is small and a finer circuit can be formed.

  The plating pretreatment agent of the present invention can be carried out with water as the main solvent. Furthermore, since it can be carried out in a neutral region, there is almost no attack on other equipment and resist. Furthermore, the liquid is stable for several months, and the pot life is long and economical. Moreover, the gel film produced can produce a highly stable film that is strong against organic solvents and acid resistance.

  Furthermore, since the manufacturing method of the electroconductive pattern formation board | substrate of this invention does not require facilities, such as sputtering, while being able to hold down the expense to capital investment, the application to the material to a large area is attained.

FIG. 1 is a photograph of a metal pattern produced according to Example 1. FIG. 2 is a photograph of a metal pattern produced according to Example 2. FIG. 3 is a photograph of the metal pattern produced in Example 3.

  In the present invention, a tin compound sol, which is a pretreatment agent for plating, is coated on the entire surface of a substrate on which a circuit pattern has been formed by photolithography, and then the resist is peeled off. At that time, since the gel coated on the resist is also removed at the same time, only the circuit pattern of the gel remains on the substrate. This is a method for producing a conductive pattern forming substrate by using this gel as an intermediate layer and forming a conductive layer by electroless plating on the gel pattern portion.

  The type of resist used for photolithography is not particularly limited, but it can be used regardless of positive type or negative type in which a resin component is dissolved in an organic solvent, and can also be used for non-liquid resists such as dry films. .

  For the resist stripping, an organic solvent is mainly used, but the resist is not limited as long as it is a solvent capable of stripping the resist such as an alkaline aqueous solution. For example, ketones, alcohols, amines and the like can be used. Further, it can be applied to a non-solution resist stripping process such as oxygen plasma.

  As a coating method of the electroless plating pretreatment agent, known methods such as spin coating, dip coating, and spraying can be applied.

  The sol, which is a pretreatment agent for electroless plating, is considered to be a liquid in which tetravalent tin compounds such as tin oxide and stannic acid are dispersed in water as a main component. Electroless plating is enabled by bringing about an action of adsorbing silver complex ions or palladium complex ions by an activation treatment with an aqueous solution or an aqueous solution of palladium complex ions (hereinafter referred to as an activation treatment solution).

  The activation process may be performed at any time before and after resist stripping.

  By using a mixed sol in which silver complex ions or palladium complex ions are mixed in advance as a plating pretreatment agent, it is possible to omit the activation treatment and perform electroless plating to form a conductive pattern.

  The plating pretreatment agent used in the present invention uses a sol of a tetravalent tin compound as a main component. The tin salt that is the raw material of the sol is not particularly limited, and examples thereof include stannous chloride, stannic chloride, tin acetate, tin bromide, tin oxalate, tin nitrate, and tin sulfate. .

  In addition, the raw material of silver complex ion or palladium complex ion used in the mixed sol or activation treatment liquid is not particularly limited, but silver chloride, silver nitrate, silver sulfate, palladium chloride, palladium sulfate, palladium nitrate, etc. Can be mentioned. Complex ligands include EDTA, bipyridine, ammonia, acetylacetone, glycine, alkyl monocarboxylic acids, alkyldicarboxylic acids, hydroxy acids, polyethyleneamines, alkylamines, alkanolamines, hydantoins, thiosulfuric acid, methanesulfonic acid , Fluoro, chloro, bromo, cyano, aqua and other ligands can be used.

  The solvent used is mainly water alone, but a water-soluble organic solvent such as alcohol can also be used. Moreover, water and these organic solvents can also be mixed and used.

  The tin concentration in the sol is preferably 0.0001 to 5.0 mol / L, more preferably 0.001 to 0.2 mol / L. The concentration of palladium complex ions and silver complex ions in the mixed sol or in the activation treatment liquid is preferably 0.00001 to 0.1 mol / L. If it is in the other range, the agglomeration may occur and plating may become non-uniform.

  The pH of the plating pretreatment agent and the activation treatment liquid is preferably in the range of 2 to 13, and more preferably in the range of 3 to 12. Outside this range, there is a risk of precipitation in the solution.

  It is preferable to use the plating pretreatment agent at room temperature.

  Viscosity adjustment of plating pretreatment agent and improvement of wettability to substrate, thickener such as ethylene glycol, drying aid, wetting and dispersing agent, anti-settling agent, surface conditioner, surfactant can also be mixed

  Since the plating pretreatment agent according to the present invention is a solution process, it can also be applied to complicated three-dimensional shapes represented by through-hole vias.

  After the coating of the plating pretreatment agent according to the present invention, it is necessary to perform a reduction treatment for reducing the palladium complex ions or silver complex ions on the gel to metal ions before the electroless plating step. However, this treatment can be omitted when a reducing agent that reduces palladium complex ions or silver complex ions is present in the plating bath.

  As the reducing agent for performing the reduction treatment, known reducing agents such as hypophosphorous acid, hydrazine, formalin, sodium borohydride, dimethylamine borane, ascorbic acid, hydroquinone and glucose can be used.

  The plating that can use the plating pretreatment agent of the present invention is not particularly limited, and examples thereof include electroless plating of nickel, copper, cobalt, tin, gold, silver, and the like.

  After the electroless plating process of the present invention, appropriate thick plating may be performed using electroplating or the like.

  Moreover, if this invention is used, electroconductivity plating film | membrane with a thin film thickness may be produced on an insulating transparent base material on a pattern, and electroconductivity can also be provided to a base material, ensuring the transmittance | permeability.

The base material applicable to the present invention is an insulating material such as glass, ceramics, and plastic, but can also be applied to a conductive material.

Next, although an example is given and the present invention is explained, the present invention is not limited to the following examples.
(Preparation of electroless plating pretreatment agent) 0.1 mol / L of stannic chloride was dissolved in distilled water, and the pH was adjusted to 6-8. The resulting precipitate was taken out, washed, and dispersed in distilled water to prepare a tin compound sol.
(Wiring pattern production) A resist (S1818G manufactured by Rohm and Haas) was applied to a glass substrate, and a wiring pattern was drawn by photolithography using a developer (MICROPOSIT MFCD-26 DEVELOPER manufactured by Rohm and Haas). Thereafter, the substrate was immersed in the sol and pulled up to form a gel coating film on the substrate. Then, the resist was removed by immersing the substrate in acetone and 2-propanol to prepare a gel wiring pattern.
(Activation treatment step) The above-formed glass substrate was immersed in an aqueous palladium complex solution prepared from palladium chloride to adsorb palladium ions on the substrate surface.
(Electroless plating treatment process) Electroless nickel-phosphorus plating was performed on the glass substrate subjected to the above pretreatment. The obtained conductive pattern is shown in FIG. A conductive pattern of about 4/4 (μm) of L / S made of nickel plating was produced.

A wiring pattern was drawn on the polyimide whose surface was modified by the same treatment method as in Example 1.
(Activation treatment step) The polyimide substrate formed with the pattern was immersed in an aqueous silver complex solution using silver nitrate as a raw material to adsorb silver ions on the surface of the substrate.
(Electroless plating process) The pretreated polyimide substrate was immersed in an aqueous dimethylamine borane solution to reduce the adsorbed silver ions. Thereafter, electroless copper plating was performed. The obtained plating film is shown in FIG. L / S made of copper plating produced a conductive pattern of about 4/4 (μm).

After drawing a wiring pattern on the glass by the same treatment method as in Example 1, electroless nickel-phosphorus plating was performed.
The obtained plating film is shown in FIG. A hexagonal conductive pattern having a wiring width of about 9 μm and an interval of about 70 μm made of nickel-phosphorous plating was produced. The average transmittance of the film in the wavelength region of 350 nm to 700 nm was 80% or more.

Claims (6)

  An insulating substrate and a conductive layer formed on the insulating substrate, wherein a layer made of a tin compound is formed as an intermediate layer between the substrate and the conductive layer. Pattern forming substrate.   Conductive pattern formation substrate characterized in that pattern formation by photolithography is performed on a base material, an electroless plating pretreatment agent is coated on the structure, and a conductive pattern is formed by electroless plating after removing the resist Manufacturing method.   The method for producing a conductive pattern forming substrate according to claim 2, wherein the electroless plating pretreatment agent is a sol composed of a tetravalent tin compound.   The method for producing a conductive pattern-formed substrate according to claim 2, wherein the electroless plating pretreatment agent is a mixed sol of one or both of a tetravalent tin compound and a palladium complex ion or a silver complex ion.   The manufacturing method of the conductive pattern formation board | substrate of Claim 3 immersed in the aqueous solution of one or both of palladium complex ion or silver complex ion after electroless-plating pretreatment agent coating.   The method for producing a conductive pattern-formed substrate according to any one of claims 2 to 5, wherein the electroless plating is performed after the electroless plating pretreatment agent coating and then the reduction treatment.

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