JPH07201929A - Manufacture of two-layer tab - Google Patents

Abstract

PURPOSE:To make it possible to form a metallic layer more perfectly without the occurrence of defects by electroless plating in a production method for a two-layer TAB by a substrate to which active metal particles are given. CONSTITUTION:A substrate is immersed into an acidic solution and an activation treatment is given to metal particles after forming a resist pattern when producing a two-layer TAB by forming a metal layer by plating method by using a substrate with a surface of a hydrophilic insulating film having catalyst- activated metal particles, by providing a photosensitive resist layer on the surface, by exposing with an exposure mask having a desired wiring pattern and by forming a desired resist pattern by developing. Thereafter, in succession, a metal layer is formed by electroless plating method.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for manufacturing a two-layer TAB used for mounting an LSI or the like.

[0002]

2. Description of the Related Art Two-layer TA used for mounting LSIs and the like
B is generally manufactured by a manufacturing method including the following wiring pattern forming steps. That is,
(A) a step of forming a base metal layer by a dry method such as a sputtering method or a wet method of performing electroless plating or electroless plating followed by electrolytic plating on any surface of the insulator film; (b) the base metal layer Forming a resist layer on the surface of the resist layer, (c) exposing the resist layer by intimate contact, proximity, projection exposure, or the like using an exposure mask having a desired wiring pattern, and then developing the desired resist. Obtaining a pattern, (d) forming a wiring pattern preform by electroplating the exposed underlying metal layer according to the pattern to a desired thickness of the metal layer,
(E) A step of peeling and removing the resist layer remaining on the substrate surface, and (f) A step of dissolving and removing the underlying metal layer below the resist layer.

As described above, in the conventional two-layer TAB manufacturing method, since the substrate having the underlying metal layer provided on the entire surface of the insulating film in the step (a) is used, the substrate in the step (e) is a wiring. Since the unnecessary underlying metal layer remains in the part other than the pattern preform,
In order to form an electrically independent wiring pattern in order to avoid a wiring short circuit, it was necessary to dissolve and remove this unnecessary underlying metal layer in step (f). When the base metal layer is dissolved and removed in this step (f), the wiring pattern is also dissolved at the same time because the substrate is usually immersed in a metal dissolution liquid, so that dimensional stability due to its shape deterioration and This leads to a decrease in accuracy, and in extreme cases, it has been a cause of defects such as disconnection during use.

In recent years, in particular, it has been demanded that the inner lead portion in the wiring pattern has a large number of pins and a narrow pitch in accordance with the high integration of LSI and the like.
The deterioration of the shape of the wiring pattern due to the dissolution and removal of the underlying metal layer as described above has been an obstacle to the increase in the number of pins and the reduction in pitch.

As a means for solving such inconvenience,
For example, after applying metal particles having a high catalytic activity represented by palladium to the surface of an insulator, a photosensitive resist is applied, a desired wiring pattern is formed to expose the metal particles, and the metal particles are used as a core for electroless plating. There has been proposed a method of forming a metal layer according to the wiring pattern, that is, a metal circuit to be a conductor by a method. When this method is used, it is not necessary to form the underlying metal layer as described above, so that the step of removing the underlying metal layer, which is incorporated in the conventional method, can be omitted, and as a result, the problems as described above are solved. It became possible to do.

[0006]

However, after applying the active metal fine particles by the above method, a wiring pattern is formed by a photosensitive resist and immersed in an electroless plating solution to form a metal layer by electroless plating on the wiring portion. In such a case, defects such as pits and skips and unprecipitated portions were often generated in the plated metal layer as compared with the case where the electroless plated layer was formed by the conventional method. The reason for this is that when using the conventional electroless plating method,
Immediately after applying the catalyst, while being immersed in an electroless plating solution to form a plated metal layer, in the above method, after applying the metal fine particles to the insulator surface, before being immersed in the electroless plating solution, Since the drying treatment is performed three times before the coating of the photosensitive resist, after the coating, and after the developing treatment, even a noble metal such as palladium forms an oxide film due to surface oxidation and may be added to the metal. It is considered that the fine particles do not sufficiently form the metal layer by the electroless plating method because the activity of the surface is lowered when the fine particles come into contact with the photosensitive resist or the developing solution.

[0007] The defects of the electroless plated metal layer in the wiring pattern portion directly cause a disconnection or a short circuit, so that the commercial value is completely lost.

The present invention solves the above problems in the method for producing a two-layer TAB by adding the active metal fine particles,
It is an object of the present invention to provide a method capable of more completely forming a metal layer by electroless plating.

[0009]

Means for Solving the Problems As a result of intensive research to solve the above problems, the present inventor brings an acid solution into contact with metal fine particles formed on an insulating substrate and having reduced catalytic activity. In this case, the inventors have found that the surface catalytic activity can be restored again, and have completed the present invention.

That is, the method of the present invention for solving the above-mentioned problems and achieving the object uses a substrate in which catalyst-activated metal fine particles are provided on the surface of a hydrophilized insulating film, and the surface of the substrate is exposed to light. After providing a resist layer and performing exposure using an exposure mask having a desired wiring pattern, development is performed to form a desired resist pattern, and a metal layer is formed by plating to produce a two-layer TAB. In this case, after forming the resist pattern, the substrate is immersed in an acidic solution to activate the metal fine particles, and then a metal layer is formed by an electroless plating method. Is a manufacturing method.

In the present invention, the metal used for the catalytically active metal fine particles is preferably at least one selected from gold, silver, platinum and palladium. The acidic solution used to activate the metal fine particles is preferably a dilute sulfuric acid, dilute hydrochloric acid, or phosphoric acid solution. Further, in the present invention, the photosensitive resist layer applied to the surface of the metal fine particle layer is preferably at least one of acrylic resin, rubber resin, and novolac resin,
The developing solution used in the developing method applied in forming the resist pattern is preferably an inorganic or organic developing solution having a pH of 13.5 or less.

[0012]

According to the present invention, an insulating film provided with a catalytically active metal fine particle layer is used as a substrate, a photosensitive resist layer is formed on the surface of the metal fine particle layer, and then a desired wiring pattern is provided by a conventional method. Then, the metal fine particle layer according to the pattern is exposed. However, the catalyst activation degree of the metal fine particles is lowered by the above-mentioned treatment process. Therefore, the surface of the exposed metal fine particles is immersed in a reducing solution to reactivate the metal fine particles, thereby reactivating the metal fine particles having a reduced degree of catalyst activation. Then, if a metal plating layer is formed using an electroless plating solution containing a desired metal salt, the metal thin film layer that plays the same role as that of the conventional underlying metal layer causes some defects according to the desired wiring pattern. It can be formed without any.

That is, according to the present invention, the metal fine particle layer whose catalytic activity has been lowered by the patterning treatment or the like is reactivated by bringing it into contact with a reducing solution, so that a plated metal layer obtained by the electroless plating treatment is formed. Since it is possible to solve the problem of defects such as pits and skips caused by poor deposition of plated metal, the electroless plating metal thin film layer is then electroplated by a conventional method until a sufficient thickness is obtained, and the wiring portion is formed. If a metal layer is formed, then the remaining resist is peeled off and the unnecessary catalyst layer underneath is removed, the wiring pattern other than the desired wiring pattern can be obtained without going through the dissolving and removing step of the underlying metal layer as in the conventional method. Since a substrate without a metal layer can be obtained, the cause of defects such as disconnection can be eliminated.

If, for example, an isolated pattern exists in the wiring pattern and the lead-in wire for power feeding cannot be designed, the electroplating method cannot be adopted. In such a case, the electroless plating method is continuously adopted. The thickness of the metal layer may be increased.

In obtaining the substrate used in the method of the present invention,
The method for hydrophilizing the insulating film surface may be performed by soft etching with a strong alkaline aqueous solution, and the method for forming the catalyst metal fine particle layer on the hydrophilized insulating film is not particularly limited, for example, The sensitizing activation method and the catalys accelerator method, which are generally used as the pretreatment method for applying a catalyst in the conventional electroless plating, are simple and easy, and the catalytically active metal fine particles can be easily formed on the insulating film. Can be uniformly applied. Further, the chemicals used at this time may be those conventionally used.

As another method for applying the catalytically active metal fine particles, it suffices to carry the metal fine particles as a catalyst on the insulating film. For example, the metal fine particles are dispersed in polyamic acid. In this state, it may be applied on a polyimide film as an insulator to imidize the polyimide, and the surface thereof may be soft-etched with a strong alkaline aqueous solution to expose a part of the carried metal fine particles on the surface.
As still another method, polyamic acid is applied on a polyimide film which is an insulating film, and catalytically active metal fine particles are sprayed onto the surface by a mechanical method such as sandblasting, and then the layer of polyamic acid is imidized. A method of forming a catalyst layer for electroless plating is also considered.

In the two catalyst application methods using polyamic acid described above, in the former case, metal fine particles which are not exposed by soft etching to a layer imidized with polyamic acid and do not function as a catalyst. Since there is only a region in which the electric field is embedded, there is a concern that the electric insulation may be poor. In the latter case, the metal fine particles must be exposed on the polyamic acid layer without being embedded in the polyamic acid layer, and the reproducibility is somewhat reproducible due to the metal spraying conditions for this and the viscosity control of the polyamic acid. There's a problem.

The catalytically active metal used in the present invention is preferably more electrically negative than the complex metal ion added to the electroless plating solution. For example, gold, platinum,
Examples include silver and palladium. However, from the viewpoint of easy availability and economical efficiency, it is preferable to use palladium which is widely commercially available for the catalyst application liquid.

Further, since the electroless plating solution used in the present invention is provided with a catalytically active metal as a catalyst layer on the substrate, the metal ions contained in the plating solution are gold, platinum, palladium, copper and nickel. A reduction-precipitation type plating solution, which has an autocatalytic activity such as cobalt, chromium, or the like, and which is reduced by a reducing agent such as hydrazine, sodium phosphinate, or formalin to deposit the above metal, is suitable. The thickness of the metal thin film layer obtained by the electroless plating method is not particularly limited as long as it can be electroplated in the next step.

The unnecessary catalytic metal fine particle layer remaining on the portion other than the wiring pattern needs to be removed in order to ensure the electrical reliability of the two-layer TAB. By carrying out soft etching with a strong alkaline aqueous solution used for hydrophilization or an alkaline aqueous solution having a pH of 13.5 or less, the wiring pattern can be hardly affected.

The production of a two-layer TAB by the method of the present invention will be described below in more detail based on one embodiment thereof. (1) Any surface of an insulating film made of a polyimide resin or the like is soft-etched with a strong alkaline liquid to be hydrophilic to make it the first surface, and the other surface as the second surface. (2) Electroless containing palladium as a catalyst metal A catalyst metal fine particle layer is formed on the first surface of the insulating film by using a plating catalyst applying liquid. (3) A photosensitive resist is applied to both surfaces to a predetermined thickness to form a resist layer. (4) An exposure mask having a desired wiring pattern and a sprocket hole pattern is applied to the first surface on which the resist layer is formed, and an exposure mask having a desired device hole pattern and a sprocket pattern is applied to the second surface, and then a conventional method is used. Exposure and development are performed to form a desired resist pattern on each surface. (5) On the catalyst metal fine particle layer exposed on the first surface, electroless plating is performed by a conventional method to form a metal thin film layer. (6) According to the wiring resist pattern on the first surface, the metal thin film layer is electroplated to form a conductor metal layer having a desired thickness. (7) The wiring resist pattern is removed. (8) The remaining catalyst metal fine particle layer is removed.

Then, after the same processing as in the conventional method, or after removing only the remaining resist layer, it is processed in the same manner as in the conventional method and before finishing plating such as gold or tin plating is performed as the final step. The catalyst metal fine particles adsorbed on the surface of the insulator are removed by soft etching the surface of the insulator with a strong alkaline aqueous solution.

As described above, in the method of the present invention, it is necessary that the catalyst metal particle layer is not substantially removed when the wiring resist pattern is provided. Further, the type of the photosensitive resist used is not suitable such that the catalyst metal fine particles are reversely carried and separated from the surface of the insulating film during development.

Further, the developing condition satisfying this condition depends on the surface state of the insulating film on which the catalytic metal fine particles are adsorbed, but for example, when a strong alkaline aqueous solution is used for hydrophilicizing the insulating surface, In order to achieve this, the pH value of the developer to be used must be within a range such that the hydrophilized film surface layer does not disappear by etching.

Since this pH value range correlates with the pH of the strong alkaline aqueous solution used for the hydrophilic treatment,
It may be preliminarily determined according to the developer actually used.
Examples of the developer satisfying such a developing condition and the resist applicable thereto include acrylic resin, novolac resin and the like when an organic alkaline or inorganic alkaline developer having a pH of 13.5 or less is used. A resist containing a main component is suitable, and when an organic neutral type developing solution is used, a resist containing a rubber resin as a main component is suitable.

[0026]

EXAMPLES Next, examples of the present invention will be described.

A 50 μm thick polyimide resin film (manufactured by Toray-Dupont, product name “Kapton 200V”) is used as an insulator film, and both surfaces thereof are soft-etched with an ordinary strong alkaline etching solution and then diluted with dilute hydrochloric acid. The surface is made hydrophilic by immersing it in a solution to neutralize it, and then dipping it in a catalyzing solution and an accelerating solution (both made by Okuno Chemical Industries) to adsorb palladium fine particles as a catalytic metal layer on the polyimide resin film surface. Then, it was dried to obtain a substrate.

Next, a photosensitive resist (trade name "FSR-S", manufactured by Fuji Chemical Industry Co., Ltd.) was applied to both sides of the polyimide film substrate provided with the catalytic metal fine particles, and each of them was coated with 30 times.
A μm photosensitive resist film was formed. Then, using a photomask, a wiring lead pattern and VI are provided for each TCP (tape carrier plate) pattern such that a 48 mm wide tape is vertically arranged in two rows to form a total of four pieces.
The two patterns of the A-hole forming metal mask pattern are brought into close contact with each other so that the wiring pattern is on the first surface and the VIA hole forming metal mask pattern is on the second surface. After performing the first double-sided exposure (each exposure amount was 800 mJ / cm ² ) using, a developing solution and a rinsing solution (“FSR developing solution” and “FSR rinsing solution” manufactured by Fuji Pharmaceutical Co., Ltd.) Was used as a stock solution to develop at room temperature to form a predetermined resist pattern on each surface. A lead wire pattern for electroplating may be provided on the wiring lead pattern formed on the first surface, if necessary.

Next, the substrate is immersed in a 20% sulfuric acid solution for 1 minute to wash it with water, and then immersed in a known electroless copper plating solution containing copper sulfate, EDTA, etc. for 10 minutes to form a resist pattern. A copper thin film layer is formed by depositing an electroless copper plating film on the catalyst-applied surface of the exposed polyimide film, and then electrolytic copper plating is performed on the copper thin film layer by a semi-additive method to first provide a copper wiring lead. On the surface
A VIA hole forming copper mask was formed. The electroplating solution used here may be a known sulfuric acid-based electroplating solution such as copper sulfate, and if necessary, a commercially available additive such as a brightener may be added thereto. The electrolysis conditions are room temperature and current density 2
A general condition of A / dm ² may be applied.

Thereafter, the upper surfaces of the metal patterns on the first surface and the second surface were immersed in an aqueous solution containing alkylimidazole as a main component (trade name "Grihole R" manufactured by Shikoku Chemicals Co., Ltd.) to coat the surfaces with an organic complex film. The resist layer remaining on both sides is covered with a resist stripper (Fuji Yakuhin Kogyo Co., Ltd., "F
The substrate was immersed in a dilute sulfuric acid solution to remove the organometallic complex coating covering the upper surfaces of the metal patterns on the first surface and the second surface by dissolution.

Next, a "FSR-S" resist is applied to the entire first surface to form a protective resist layer having a thickness of 20 .mu.m so as to cover the entire first surface. The VIA hole is formed by dipping and etching the polyimide portion exposed on the second surface, and the VIA formed on the second surface using the electroless plating solution described above.
A metal film is formed on the entire surface including the wall surface of the hole, and the metal film is subjected to electroplating by using the above-described electroplating solution with the metal film as a cathode, and then the second surface is formed. Photosensitive resist (trade name “PMER” manufactured by Tokyo Ohka Kogyo Co., Ltd.) is applied on the surface to form a resist film with a thickness of 15 μm, and the same size glass mask as that used in the first exposure is used. A second exposure and development were performed based on the formulation of the photosensitive resist, and the resist film on the second surface was patterned into a ground shape such as a device hole and an outer lead hole.

Then, using the pattern as a mask, the metal film exposed on the second surface and the metal layer formed on the protective resist layer on the first surface are dissolved and removed with a hydrochloric acid acidic solution, and then on the second surface. Strips and removes the remaining photoresist film,
The polyimide film was dissolved in a strong alkaline solution using the obtained ground metal layer on the second surface as an etching mask, and then the protective resist film on the first surface was peeled off using the above-mentioned "FSR stripping solution".

After that, when a lead wire for electroplating was provided in the wiring lead portion, punching processing was performed to separate the lead portion from the lead wire. Next, soft etching was performed with a strong alkaline etching solution to remove the catalyst metal fine particle layer existing on the polyimide exposed on the first surface. Finally, a surface treatment such as gold plating was applied to the wiring lead portion on the first surface to obtain a two-layer TAB having metal patterns on both surfaces of the insulating film.

The two-layer TAB obtained in this example is
When forming the wiring portion, the wiring lead thus formed does not have the disadvantages such as disconnection due to the deterioration of the shape because the underlying metal melting step which has been conventionally performed is unnecessary. For this reason, the two-layer TAB obtained in this example has a frequency of 1 GHz.
It can be used with sufficient reliability for mounting the above high-speed IC capable of processing high-speed signals.

In this example, a two-layer TAB having metal patterns on both sides of a polyimide resin film used as an insulator film was manufactured, but wiring leads were formed only on one side of the polyimide resin film. It goes without saying that the method of the present invention can also be applied to a two-layer TAB.

[0036]

As described above, according to the present invention,
Using an insulating substrate with catalytically active metal fine particles,
In the production of the two-layer TAB, the decrease in the activity of the metal fine particles caused by the patterning treatment or the like is reactivated by bringing the catalyst metal particles into contact with a reducing acid solution such as dilute sulfuric acid, whereby electroless plating is performed. The effect is high because defects such as disconnection can be reduced by preventing the occurrence of defects in the plated metal film due to defective deposition of plated metal during processing. Further, since the two-layer TAB obtained by the present invention is excellent in throwing power and uniform deposition of the electroless plating on a surface having a fine and complicated shape, it is possible to produce a two-layer TAB having an extremely fine wiring pattern. Become.

Claims (4)

[Claims] 1. A substrate in which catalytically active metal fine particles are provided on the surface of a hydrophilized insulating film, a photosensitive resist layer is provided on the surface of the substrate, and exposure is performed using an exposure mask having a desired wiring pattern. After that, development is performed to form a desired resist pattern, and when a metal layer is formed by a plating method to produce a two-layer TAB, after forming the resist pattern, the substrate is immersed in an acidic solution to A method for producing a two-layer TAB, which comprises activating a metal fine particle, and subsequently forming a metal layer by an electroless plating method. 2. The acidic solution for activation treatment is dilute sulfuric acid,
The two-layer TA according to claim 1, which is a dilute hydrochloric acid or phosphoric acid solution.
Manufacturing method of B. 3. The method for producing a two-layer TAB according to claim 1, wherein the catalytically active metal fine particles are one or more selected from the group consisting of gold, silver, platinum and palladium. 4. The photosensitive resist applied to the surface of the catalytically active metal fine particle layer is at least one selected from acrylic resin, rubber resin and novolac resin,
The method for producing a two-layer TAB according to claim 1, wherein the developing solution used in the developing method applied to form the resist pattern is an inorganic or organic developing solution having a pH of 13.5 or less.